Mining Safety and Sustainability

Journal Name	Impact Factor	CiteScore	Launched Year	First Decision (median)	APC
Energies energies	3.0	6.2	2008	17.5 Days	CHF 2600
Minerals minerals	2.2	4.1	2011	18 Days	CHF 2400
Safety safety	1.8	3.2	2015	27.3 Days	CHF 1800
Sensors sensors	3.4	7.3	2001	16.8 Days	CHF 2600
Sustainability sustainability	3.3	6.8	2009	20 Days	CHF 2400

10 pages, 1038 KiB

Open AccessArticle

Recovery of Tellurium from Waste Anode Slime Containing High Copper and High Tellurium of Copper Refineries

by Chinmaya Kumar Sarangi, Abdul Rauf Sheik, Barsha Marandi, Vijetha Ponnam, Malay Kumar Ghosh, Kali Sanjay, Manickam Minakshi and Tondepu Subbaiah

Sustainability 2023, 15(15), 11919; https://doi.org/10.3390/su151511919 - 3 Aug 2023

Cited by 3 | Viewed by 1821

Abstract

Tellurium is used in cadmium tellurium-based solar cells. Mercury cadmium telluride is used as a sensing material for thermal imaging devices. High-purity tellurium is used in alloys for electronic applications. It is one of the important raw materials for solar energy applications. It [...] Read more.

Tellurium is used in cadmium tellurium-based solar cells. Mercury cadmium telluride is used as a sensing material for thermal imaging devices. High-purity tellurium is used in alloys for electronic applications. It is one of the important raw materials for solar energy applications. It is used as an alloying element in the production of low-carbon steel and copper alloys. Tellurium catalysts are used chiefly for the oxidation of organic compounds and as vulcanizing/accelerating agents in the processing of rubber compounds. Even though several researchers tried to recover tellurium from different raw materials, there is no attempt to develop a process flow sheet to recover tellurium from waste anode slime having a high tellurium concentration. In this study, optimum conditions were developed to recover Te and Cu from anode slime with the composition Cu: 31.8%, Te: 24.7%, and As: 0.96%. The unit operations involved are leaching, purification, and electro winning. The optimum conditions for producing Te at a recovery of 90% are found to be roasting of anode slime at 450 °C without the addition of soda ash followed by leaching in 1 M NaOH at 10% pulp density for 2 h. The purity of Te metal achieved was up to 99.99%, which could provide a sustainable energy future. The major impurities of the tellurium are observed to be in the order: Se > Sb > As > Cu. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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16 pages, 2379 KiB

Open AccessArticle

Sustainable Rehabilitation of Post-Bauxite Mining Land for Albizia falcata Cultivation Using Specific Location Amelioration Technology

by Denah Suswati and Nugra Irianta Denashurya

Sustainability 2023, 15(14), 10959; https://doi.org/10.3390/su151410959 - 13 Jul 2023

Cited by 3 | Viewed by 1880

Abstract

Bauxite mining, catalyzed by the escalating global demand for aluminum, leads to serious environmental repercussions, necessitating the development of efficient land rehabilitation techniques. This study presents a sustainable solution for post-bauxite mining land rehabilitation by leveraging red mud waste and cow manure fertilizer. [...] Read more.

Bauxite mining, catalyzed by the escalating global demand for aluminum, leads to serious environmental repercussions, necessitating the development of efficient land rehabilitation techniques. This study presents a sustainable solution for post-bauxite mining land rehabilitation by leveraging red mud waste and cow manure fertilizer. Applied in PT Antam, Sanggau Regency, West Kalimantan, this research examines the potential of these ameliorants to restore ecological functions and promote the growth of Albizia falcata plants. Our findings reveal a remarkable enhancement in soil pH levels and nutrient availability (N, P, K, Ca, Mg, and Na) when applying a blend of 10% red mud and 20% cow manure fertilizer. Consequently, a significant improvement in the growth of Albizia falcata plants by factors ranging from 8 to 13 times was recorded. These results, alongside potential economic benefits, highlight the promise of this approach not to only confront the challenges posed by bauxite mining but also to contribute to global land rehabilitation strategies. While this study provides substantial insights, it recommends further exploration of this method involving diverse plant species, treatments with different ameliorants, and a broader range of observed variables. The study underscores the critical role of government intervention through stringent regulations and the need for a more comprehensive environmental and cost-benefit analysis to foster sustainable mining practices and responsible land rehabilitation. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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15 pages, 6701 KiB

Open AccessArticle

Compaction Response of Mining-Induced Rock Masses to Longwall Overburden Isolated Grouting

by Jian Li, Dayang Xuan, Jialin Xu, Zebin Dong and Chaochao Wang

Minerals 2023, 13(5), 633; https://doi.org/10.3390/min13050633 - 30 Apr 2023

Cited by 5 | Viewed by 1918

Abstract

Surface subsidence in coal mine areas can cause serious geological hazards. After a coal seam is mined, the overlying rock layers fracture, collapse, and expand; the fractured and bulking rock masses are then continuously compacted under the action of overburden load, which eventually [...] Read more.

Surface subsidence in coal mine areas can cause serious geological hazards. After a coal seam is mined, the overlying rock layers fracture, collapse, and expand; the fractured and bulking rock masses are then continuously compacted under the action of overburden load, which eventually leads to surface subsidence. Overburden isolated grout filling via surface boreholes, and high-pressure grouting to mining-induced fissures under the hard rock layer, uses the grouting pressure to compact the lower fractured and bulking rock masses in advance, replacing the subsidence void and effectively controlling the surface subsidence. The characteristics of rock mass collapse, bulking, and compaction associated with mining and grouting are the key to the design of grouting parameters and surface subsidence control. In this paper, a theoretical model of the rock masses’ compactness during grouting injection is proposed, which determines the compaction of rock masses under the action of grouting filling. An experimental study was conducted to reproduce the grouting pressure evolution and the rock masses compaction in response to grout filling. The results indicated that the rock mass compaction was small in the no-pressure stage, and that the low-pressure and pressure-boost stages were key to generating the compaction effect of the grout filling. It was found that compaction grouting substantially increased the filled volume by transforming the fractured and bulking space of the rock masses into a filled space. Using engineering measurement data, the rock masses compaction law for grouting is verified. This paper provides a theoretical basis for the design of overburden grouting parameters and the evaluation of subsidence control effectiveness. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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17 pages, 3931 KiB

Open AccessArticle

Dynamic Response Difference of Hydraulic Support under Mechanical-Hydraulic Co-Simulation: Induced by Different Roof Rotation Position and Hysteresis Effect of Relief Valve

by Qingliang Zeng, Chen Ma, Zhaosheng Meng, Jiantao Wang, Penghui Xu and Xiaowan Lei

Energies 2023, 16(4), 2052; https://doi.org/10.3390/en16042052 - 19 Feb 2023

Viewed by 1767

Abstract

As key supporting equipment in coal mining, hydraulic supports are vulnerable to impact pressure from roof movement and deformation. In this paper, a mechanical-hydraulic co-simulation platform for hydraulic supports is established. Moreover, the rationality of the simulation platform is verified. Based on this [...] Read more.

As key supporting equipment in coal mining, hydraulic supports are vulnerable to impact pressure from roof movement and deformation. In this paper, a mechanical-hydraulic co-simulation platform for hydraulic supports is established. Moreover, the rationality of the simulation platform is verified. Based on this platform, the rigid-flexible coupling impact dynamics model of hydraulic support is built. Finally, by delaying the opening time of the relief valve, the energy dissipation problem of the relief valve hysteresis effect on the hydraulic support system under the rotary impact is discussed. The results indicate that the rotary load acting on the hydraulic support decreases gradually with the backward movement of the roof rotary position, which causes the peak pressure in the column to decrease (by 69 MPa). The hinge point load of different parts shows different load transfer laws. The hysteresis effect of the relief valve prolongs the energy release time of the system, increasing the pressure in the column by 23 MPa. The instantaneous opening speed of the relief valve spool reaches 15.7 m/s, and the hinge point between the top beam and the column is most sensitive to the hysteresis effect (impact coefficient increases by 0.63). Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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17 pages, 8227 KiB

Open AccessArticle

Failure Mechanism and Stability Control of Soft Roof in Advance Support Section of Mining Face

by Jun Li, Jianju Ren, Chen Li, Wenbo Zhang and Fei Tong

Minerals 2023, 13(2), 178; https://doi.org/10.3390/min13020178 - 26 Jan 2023

Cited by 3 | Viewed by 1309

Abstract

There is a great risk of roof falls in the advance support section of the mining face (ASSoMF), and it is difficult to control the roof. Based on the soft roof of Lijiahao coal mine, this paper studies the stress distribution of the [...] Read more.

There is a great risk of roof falls in the advance support section of the mining face (ASSoMF), and it is difficult to control the roof. Based on the soft roof of Lijiahao coal mine, this paper studies the stress distribution of the ASSoMF and the space-time evolution of the surrounding rock plastic zone by using theoretical analysis and numerical simulation, and reveals its failure mechanism. Based on the control effect of support resistance on plastic zone, it is proposed that the advance support should mainly adapt to the roadway deformation. Advance equipment without repeated support for mechanized movement has been developed, and the support timing analysis and strength check have been carried out. Results show that the roadway at ASSoMF is in a non-uniform stress field, the confining pressure ratio reaches 1.5~7, and the surrounding rock forms asymmetric failure; the principal stress direction deflects, the angle between it and the vertical direction is about 10°~25°, and the plastic zone of the surrounding rock also rotates to the roadway roof. The proposed equipment can adapt to the characteristics of an unsymmetrical large deformation of a soft roof, and can effectively bear the roof load and maintain the stability of the roadway. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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15 pages, 20000 KiB

Open AccessArticle

Risk Field of Rock Instability using Microseismic Monitoringdata in Deep Mining

by Longjun Dong, Huanyu Zhu, Fang Yan and Shuijin Bi

Sensors 2023, 23(3), 1300; https://doi.org/10.3390/s23031300 - 23 Jan 2023

Cited by 9 | Viewed by 1887

Abstract

With the gradual depletion of surface resources, rock instability caused by deep high stress
and mining disturbance seriously affects safe mining. To create effective risk management, a rock
instability risk field model using microseismic monitoring data is proposed in this study. Rock
instability [...] Read more.

With the gradual depletion of surface resources, rock instability caused by deep high stress
and mining disturbance seriously affects safe mining. To create effective risk management, a rock
instability risk field model using microseismic monitoring data is proposed in this study. Rock
instability risk was presented visually in 3D visualization. The in-situ microseismic monitoring
data was collected and analyzed to make calculation of peak ground velocity (PGV), peak ground
acceleration (PGA), energy flux, energy and seismic moment. Indicator weights of PGV, PGA, energy
flux are confirmed by using the analytic hierarchy process (AHP) to calculate risk severity. The Copula
function is then used to solve the joint probability distribution function of energy and seismic moment.
Then the spatial distribution characteristics of risk can be obtained by data fitting. Subsequently, the
three-dimensional (3D) risk field model was established. Meanwhile, the established risk field is
verified by comparing monitoring data without disturbance and the blasting data with disturbance.
It is suggested that the proposed risk field method could evaluate the regional risk of rock instability
reasonably and accurately, which lays a theoretical foundation for the risk prediction and management
of rock instability in deep mining. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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24 pages, 9012 KiB

Open AccessArticle

Numerical Simulation Study of the Effect of Fine View Pore Structure on Rock Burst

by Haoru Yang, Qingwang Lian, Jin Shang and Xinlin Chen

Minerals 2023, 13(2), 146; https://doi.org/10.3390/min13020146 - 18 Jan 2023

Cited by 1 | Viewed by 1662

Abstract

With the gradual shift of coal mining to deeper levels in recent years, rock burst has become one of the primary dynamic hazards faced in deep mining. It has been shown that the pore structure in rocks affects the mechanical properties, but the [...] Read more.

With the gradual shift of coal mining to deeper levels in recent years, rock burst has become one of the primary dynamic hazards faced in deep mining. It has been shown that the pore structure in rocks affects the mechanical properties, but the relationship with the rock burst phenomenon still needs to be clarified. In this paper, we investigated the causes and effects of pore structure on impact mechanical properties using RFPA2D numerical simulation software, established several numerical models with different porosities and pore diameters, and analyzed the stress-strain curves, the relationships between porosity and pore diameter and each the bursting liability indices of the coal rock body were elaborated, and the fitting equations in the range of porosity (0%~10%) and pore diameter (0.25~2.0 mm) were obtained. The results showed that the increase in porosity and pore diameter effectively attenuated the bursting ability of coal rocks, which has some reference significance for the study of early warning and prevention of rock burst phenomenon. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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15 pages, 5255 KiB

Open AccessArticle

Effects of Aeolian Sand and Water−Cement Ratio on Performance of a Novel Mine Backfill Material

by Guodong Li, Hongzhi Wang, Zhaoxuan Liu, Honglin Liu, Haitian Yan and Zenwei Liu

Sustainability 2023, 15(1), 569; https://doi.org/10.3390/su15010569 - 29 Dec 2022

Cited by 2 | Viewed by 1703

Abstract

The gob-side entry retaining (GER) technique, as the family member of the pillarless coal mining system, is becoming popular, mainly attributed to its high resource recovery rate and significant environmental benefits. Seeking cost-effective backfill material to develop the roadside backfilling body (RBB) is [...] Read more.

The gob-side entry retaining (GER) technique, as the family member of the pillarless coal mining system, is becoming popular, mainly attributed to its high resource recovery rate and significant environmental benefits. Seeking cost-effective backfill material to develop the roadside backfilling body (RBB) is generally a hot topic for coal operators and scholars. Except for its relatively high cost, the other shortcoming of the widely used high-water backfill material is also obvious when used in arid, semi-arid deserts or Gobi mining areas lacking water. The modified high-water backfill material (MBM) mixed with aeolian sand was recently developed as an alternative to conventional backfill materials. Some critical parameters affecting both the physical and mechanical properties of the MBM, including the amount of the aeolian sand and water-to-powder ratio of the high water-content material, have been experimentally investigated in the present research. Test results showed that the MBM featured high early strength and bearing capability after a large post-peak deformation. In particular, the adjustable setting time of the MBM through changing the amount of sand widens its application in practice. Unlike the high-water backfill material, the MBM is a typical elastoplastic material; the stress-strain curves consist of pore compression, elastic deformation, yielding, and total failure. Note that both the peak and residual strength of the MBM increased as the doping amount of aeolian sand increased, which is probably because of the impacted aeolian sand and the uniform reticular structure of the ettringite in the MBM. Compared with the high-water backfill material, only limited cementitious material and water resources are requested to cast the RBB, which provides more economical and environmental benefits for the application of the GER technique in the arid, semi-arid deserts or the Gobi mining areas. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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36 pages, 1817 KiB

Open AccessReview

Block Caving Mining Method: Transformation and Its Potency in Indonesia

by Sari Melati, Ridho Kresna Wattimena, David Prambudi Sahara, Syafrizal, Ganda Marihot Simangunsong, Wahyu Hidayat, Erwin Riyanto and Raden Roro Shinta Felisia

Energies 2023, 16(1), 9; https://doi.org/10.3390/en16010009 - 20 Dec 2022

Cited by 4 | Viewed by 15093

Abstract

The block caving mining method has become increasingly popular in the last two decades. Meanwhile, Indonesia has several potential ore bodies which have not yet determined suitable mining methods. The references to block caving mining projects worldwide and the potency of metal deposits [...] Read more.

The block caving mining method has become increasingly popular in the last two decades. Meanwhile, Indonesia has several potential ore bodies which have not yet determined suitable mining methods. The references to block caving mining projects worldwide and the potency of metal deposits in Indonesia were reviewed to determine the requirements of ore bodies suitable for mining using the transformed block caving method. This method can be applied on a blocky ore body with a thickness of 200–800 m, various rock mass strengths until 300 MPa, from low to high (from 0.3% Cu until more than 1.0% Cu), but of uniform grade and at a depth from 500 to 2200 m. The technical specifications for running block caving mines have been synthesized, including preparation methods, undercutting strategy, mine design, mining equipment and monitoring. Considering the requirements and the successful practice of the block caving project in the Grasberg Caving Complex as a role model, the Indonesian government should concentrate on the detailed exploration of porphyry deposits and feasibility studies on applying the method to the prospective ore bodies, i.e., Onto, Tambulilato, Tumpangpitu and Randu Kuning. In addition, the exploration method, cost, operation, environment, mining policy and social geology are important aspects worth noting. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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14 pages, 4920 KiB

Open AccessArticle

Design Method and Application of Stope Structure Parameters in Deep Metal Mines Based on an Improved Stability Graph

by Xingdong Zhao and Xin Zhou

Minerals 2023, 13(1), 2; https://doi.org/10.3390/min13010002 - 20 Dec 2022

Cited by 7 | Viewed by 3100

Abstract

Deep mining has become an inevitable trend of mining development. Previously conducted studies have established that reasonable stope structure parameters are the premise to ensure the safe and efficient production of deep mines. In order to ensure the safety of deep mining, in [...] Read more.

Deep mining has become an inevitable trend of mining development. Previously conducted studies have established that reasonable stope structure parameters are the premise to ensure the safe and efficient production of deep mines. In order to ensure the safety of deep mining, in this paper, we systematically review the existing stope structure parameter design methods, and then put forward a deep stope structure design method based on the stability of mining rock mass. Based on rock mass quality classification, this method uses a critical span graph and an improved stability graph, and fully considers the influence of joint occurrence and mining stress on the stability of surrounding rock, to design the stope structural parameters. Taking into consideration the deterioration of the quality of deep rock mass, we collect mining data at home and abroad, improve the stability graph, and make it suitable for the design of stope structural parameters with different mining methods. The design process of stope structural parameters is expounded through field engineering cases, and it has specific guiding significance for the design of stope structural parameters in deep metal mines. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 5676 KiB

Open AccessArticle

Coal Wall Spalling Mechanism and Grouting Reinforcement Technology of Large Mining Height Working Face

by Hongtao Liu, Yang Chen, Zijun Han, Qinyu Liu, Zilong Luo, Wencong Cheng, Hongkai Zhang, Shizhu Qiu and Haozhu Wang

Sensors 2022, 22(22), 8675; https://doi.org/10.3390/s22228675 - 10 Nov 2022

Cited by 5 | Viewed by 1599

Abstract

To control the problem of coal wall spalling in large mining height working faces subject to mining, considering the Duanwang Mine 150505 fully mechanized working face, the mechanism of coal wall spalling in working faces was investigated by theoretical analysis, numerical simulation and [...] Read more.

To control the problem of coal wall spalling in large mining height working faces subject to mining, considering the Duanwang Mine 150505 fully mechanized working face, the mechanism of coal wall spalling in working faces was investigated by theoretical analysis, numerical simulation and field experiment. Based on analysis of coal wall spalling in the working face, a new grouting material was developed. The stress and plastic zone changes affecting the coal wall, before and after grouting in the working face, were analyzed using numerical simulation and surrounding rock grouting reinforcement technology was proposed for application around the new grouting material. The results showed that: (1) serious spalling of the 150505 working face was caused by the large mining height, fault influence and low roof strength, and (2) the new nano-composite low temperature polymer materials used have characteristics of rapid reaction, low polymerization temperature, adjustable setting time, high strength and environmental protection. Based on analysis of the working face coal wall spalling problem, grouting reinforcement technology based on new materials was proposed. Industrial tests were carried out on the working face. Field monitoring showed that the stability of the working face coal wall was significantly enhanced and that rib spalling was significantly improved after comprehensive anti-rib-spalling grouting measures were adopted. These results provide a basis for rib spalling control of working faces under similar conditions. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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15 pages, 5134 KiB

Open AccessArticle

Evaluation of Compressive Geophysical Prospecting Method for the Identification of the Abandoned Goaf at the Tengzhou Section of China’s Mu Shi Expressway

by Shukun Zhang, Peng Jiang, Lu Lu, Shuai Wang and Haohao Wang

Sustainability 2022, 14(21), 13785; https://doi.org/10.3390/su142113785 - 24 Oct 2022

Cited by 6 | Viewed by 1354

Abstract

Subsidence deformation of abandoned goafs can induce cracking, distortion and even collapse of surface buildings (structures), and thus, subsidence deformation poses a great threat. Accurate detection of the abandoned goaf location and overburden morphology is an important prerequisite for stability evaluation and scientific [...] Read more.

Subsidence deformation of abandoned goafs can induce cracking, distortion and even collapse of surface buildings (structures), and thus, subsidence deformation poses a great threat. Accurate detection of the abandoned goaf location and overburden morphology is an important prerequisite for stability evaluation and scientific management of surface buildings (structures), and effective detection methods are bottlenecks for accurate detection. Taking the abandoned goaf in the Tengzhou section of China’s Mu Shi expressway as an engineering example, step-by-step detection, traditional detection and combination methods are used to determine the location of the underlying abandoned goaf and overburden morphology. First, we conduct disaster investigation on the expressway and surface within the affected area of the abandoned goaf and initially determine the detection area. Then, according to the principle that the detection range can be examined step-by-step from large to small, the high-density resistivity method is used for detection, and the high-resolution seismic method is further selected to analyze the target area. Then, based on the results of the resistivity method, the position of the abandoned goaf is evaluated with the high-resolution seismic method, and the distributions of the overburden subsidence, the water-filled fractured zone and the caving zone (the three belts) are determined. Finally, boreholes are drilled deep into the bottom of the abandoned goaf at specific locations and the distributions of the abandoned goaf and three belts are verified and corrected with drilling data, acoustic detection and borehole TV imaging technology, thereby providing accurate data on abandoned goafs for highway stability evaluation. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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22 pages, 3346 KiB

Open AccessArticle

Roof Fractures of Near-Vertical and Extremely Thick Coal Seams in Horizontally Grouped Top-Coal Drawing Method Based on the Theory of a Thin Plate

by Guojun Zhang, Quansheng Li, Zhuhe Xu and Yong Zhang

Sustainability 2022, 14(16), 10285; https://doi.org/10.3390/su141610285 - 18 Aug 2022

Cited by 4 | Viewed by 1600

Abstract

During the mining process of the near-vertical seam, there will be movement and collapse of the “roof side” rock layer and the “overlying coal seam,” as well as the emergence of the “floor side” rock layer roof which is more complicated than the [...] Read more.

During the mining process of the near-vertical seam, there will be movement and collapse of the “roof side” rock layer and the “overlying coal seam,” as well as the emergence of the “floor side” rock layer roof which is more complicated than the inclined and gently inclined coal seams, which causes problems with slippage or overturning damage. With the increase of the inclination of the coal seam, the impact of the destruction of the immediate roof on the stope and roadway gradually becomes prominent, while the impact of the destruction of the basic roof on the stope and the roadway gradually weakens. The destruction of the immediate roof of the near-vertical coal seam will cause a large area of coal and rock mass to suddenly rush to the working face and the two lanes, resulting in rapid deformation of the roadway, overturning of equipment, overturning of personnel, and even severe rock pressure disaster accidents, all of which pose a serious threat to coal mine safety and production. It is necessary to carry out research on the mechanical response mechanism of the immediate roof of near-upright coal seams, to analyse the weighting process of steeply inclined thick coal seam sub-level mining. A four fixed support plate model and top three clamped edges simply supported plate model for roof stress distribution are established before the first weighting of the roof during the upper and lower level mining process. The bottom three clamped edges simply supported plate model and two adjacent edges clamped on the edge of a simply supported plate model are established for roof stress distribution before periodic weighting of the roof during the upper and lower level mining process. The Galerkin method is used to make an approximate solution of deflection equation under the effect of sheet normal stress, and then roof failure criterion is established based on the maximum tensile stress strength criterion and generalized Hooke law. This paper utilizes FLAC^3D finite element numerical simulation software, considering the characteristics of steeply inclined thick coal seam sub-level mining. It undertakes orthogonal numerical simulation experiment in three levels with different depths, coal seam angles, lateral pressure coefficient, and orientation of maximum horizontal principal stress, and translates roof stress of corresponding 9 simulation experiment into steeply inclined roof normal stress. We conclude that the distribution law of normal stress along dip and dip direction of a roof under the circumstance of different advancing distances and different sub-levels. The caving pace of first weight and periodical weight were counted under the effect of the roof uniform normal stress. It can better predict the weighting situation of the working face and ensure the safe, efficient, and sustainable mining of coal mines. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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17 pages, 1027 KiB

Open AccessArticle

Avoiding Buffer Tank Overflow in an Iron Ore Dewatering System with Integrated Control System

by Ênio L. Junior, Moisés T. da Silva and Thiago A. M. Euzébio

Sustainability 2022, 14(15), 9347; https://doi.org/10.3390/su14159347 - 30 Jul 2022

Cited by 1 | Viewed by 2560

Abstract

High water usage is necessary while ore passes through the many stages of a mineral processing plant. However, a dewatering system filters the final ore pulp product to remove the water, which is reutilized in the previous processes. This step is fundamental to [...] Read more.

High water usage is necessary while ore passes through the many stages of a mineral processing plant. However, a dewatering system filters the final ore pulp product to remove the water, which is reutilized in the previous processes. This step is fundamental to reducing the fresh new water consumption. Usually, several tanks, pumps, and filters form a dewatering system—any failure or shutdowns from those components disbalance the pulp flow. The waste of many tons of water and ore products for a tailing dam is the worst consequence of a mass disbalance in a dewatering system. This paper proposes an advanced regulatory control strategy composed of cascade and override loops for a dewatering system. The main purpose is to increase the production period, even under filter failure and changes in the inlet pulp characteristics. This control strategy is evaluated using a digital model of a large-scale Brazilian iron ore processing plant. Two scenarios are investigated: the simultaneous failure of two filters and disturbances in the flow and density of the thickener. The simulation results show that the proposed control strategy could extend the period of operation of the dewatering plant under failures in the disc filters and reject significant disturbances. For the considered simulation period, the proposed solution increases the time to overflow by

72 %

when compared to the previous control strategy. Thus, it is possible to avoid the waste of approximately

2448.36

tons of ore pulp that would be sent to the tailings dam. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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21 pages, 6746 KiB

Open AccessCase Report

Interaction Mechanism of the Upper and Lower Main Roofs with Different Properties in Close Coal Seams: A Case Study

by Shengrong Xie, Yiyi Wu, Fangfang Guo, Dongdong Chen, En Wang, Xiao Zhang, Hang Zou, Ruipeng Liu, Xiang Ma and Shijun Li

Energies 2022, 15(15), 5533; https://doi.org/10.3390/en15155533 - 30 Jul 2022

Cited by 8 | Viewed by 1567

Abstract

Close-distance coal seams are widely distributed in China, and the mining of overlying coal seams leads to floor damage. To grasp the properties and the fracture spans of the damaged main roof in the underlying coal seam, combining the calculation of the floor [...] Read more.

Close-distance coal seams are widely distributed in China, and the mining of overlying coal seams leads to floor damage. To grasp the properties and the fracture spans of the damaged main roof in the underlying coal seam, combining the calculation of the floor damage depth with rock damage theory and the formulas for calculating the first and periodic weighting intervals of the damaged main roof and the instability conditions of the damaged key blocks are obtained. Three interaction stability mechanics models are proposed for key blocks with different properties of the upper and lower main roof, and the instability conditions of the lower damaged key blocks are obtained when the fracture lines overlap. When combined with a specific example, the field monitoring verified the calculation results. The research results are as follows: (1) The first and periodic weighting intervals, horizontal thrust between blocks, and critical load of instability of the damaged main roof are significantly reduced. Still, there are differences in its reduction under different loads, rotation angles, and lumpiness. (2) When the fracture lines of the upper and lower main roofs overlap, the stability of the damaged key blocks is the lowest. There are three linkage stability regions in the critical load curves of the two key blocks. (3) In this case, the damage equivalent of the main roof is 0.397, which belongs to the local damage type. Its first and periodic weighting intervals are 40 m and 16 m, which is 22% and 24% less than when there is no damage. (4) A supporting load of 0.489 MPa is required to maintain the stability of the upper key block, and the lower damaged key block is prone to rotary and sliding instability during the first and periodic weighting, respectively. Thus, the supports need to bear a total of 0.988 MPa and 0.761 MPa to maintain the stability of the two key blocks simultaneously. The ground pressure data monitored on-site is in accord with the calculation results. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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20 pages, 3937 KiB

Open AccessCase Report

Mechanism Analysis of Roof Deformation in Pre-Driven Longwall Recovery Rooms Considering Main Roof Failure Form

by Bonan Wang, Lin Mu, Mingming He and Shuancheng Gu

Sustainability 2022, 14(15), 9093; https://doi.org/10.3390/su14159093 - 25 Jul 2022

Cited by 3 | Viewed by 1577

Abstract

Pre-driven recovery rooms are used extensively for the removal of mining equipment and hydraulic supports in longwall coal mining. Roof stability is a crucial factor influencing the speed and safety of the removal of operators in pre-driven recovery rooms. The characterization of roof [...] Read more.

Pre-driven recovery rooms are used extensively for the removal of mining equipment and hydraulic supports in longwall coal mining. Roof stability is a crucial factor influencing the speed and safety of the removal of operators in pre-driven recovery rooms. The characterization of roof deformation mechanisms in recovery rooms under front abutment pressures is significant for surrounding rock control and stability evaluation. In this study, three different roof subsidence evaluation models, considering different main roof failure forms, were established. It was noticed that the main roof break position had a significant effect on recovery room roof sag. The breaking of the main roof above the main recovery room and protective coal pillar was found to be the main driving force for large roof deformations. Furthermore, field monitoring data of roof sag and coal pillar stress in the 15205 and 15206 panels of Hongliulin Coal Mine were analyzed. According to evaluation models and field monitoring data, we propose determination methods for the evaluation of recovery room roof sag and main roof break position. During the study it was found that the inversion results of the main roof break position of the recovery room in 15205 and 15206 panels were 4.2 m and 9.1 m, respectively, which are basically consistent with the results calculated by periodic weighting. The research findings provide a reference for the quantitative evaluation of recovery room roof stability and the design of support parameters and yield mining. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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12 pages, 4557 KiB

Open AccessArticle

Experimental Study on the Performance of a Novel Unidirectional Explosive Element and an Explosive Logic Network

by Fei Wang, Honghao Ma and Zhaowu Shen

Energies 2022, 15(14), 5141; https://doi.org/10.3390/en15145141 - 15 Jul 2022

Cited by 1 | Viewed by 1506

Abstract

Considering the unsafety of the present blasting network used in the blasting mining of coalfield fires, a unidirectional explosive element (named explosive diode) is proposed according to explosive logic element principles. Through theoretical and experimental analysis, the internal structure and mechanism of the [...] Read more.

Considering the unsafety of the present blasting network used in the blasting mining of coalfield fires, a unidirectional explosive element (named explosive diode) is proposed according to explosive logic element principles. Through theoretical and experimental analysis, the internal structure and mechanism of the unidirectional transmission of the detonation signal were studied. For an explosive diode, the length of the quenching channel was defined to be the key parameter. The explosive diode was implemented in the traditional blasting network, obtaining an explosive logic network. To evaluate the safety and reliability of the explosive diode and explosive logic network, detonation propagation and explosion-proof experiments were conducted in the lab. The optimum length of the quenching channel to obtain unidirectional detonation transmission was established. The results showed that the explosive diode could reliably control the propagation direction of the detonation signal when the length of the quenching channel was between 15 mm and 25 mm. The explosive logic network achieved a reliable detonation propagation and was explosion-proof. In comparison with traditional networks, the explosive logic network showed increased safety and reliability as the number of subnets increased. This is a significant improvement to mining safety and demonstrates great promise for engineering applications. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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14 pages, 3090 KiB

Open AccessArticle

Potential Uses of Artisanal Gold Mine Tailings, with an Emphasis on the Role of Centrifugal Separation Technique

by Jeanne Pauline Munganyinka, Jean Baptiste Habinshuti, Jean Claude Ndayishimiye, Levie Mweene, Grace Ofori-Sarpong, Brajendra Mishra, Adelana R. Adetunji and Himanshu Tanvar

Sustainability 2022, 14(13), 8130; https://doi.org/10.3390/su14138130 - 3 Jul 2022

Cited by 3 | Viewed by 3225

Abstract

Few investigations have focused on the potential uses of artisanal gold (Au) mine tailings, despite the fact that artisanal gold mining activity contributes to environmental issues such as greenhouse gas. Mineralogical characterizations of artisanal gold mine tailings in Miyove gold mine (Baradega and [...] Read more.

Few investigations have focused on the potential uses of artisanal gold (Au) mine tailings, despite the fact that artisanal gold mining activity contributes to environmental issues such as greenhouse gas. Mineralogical characterizations of artisanal gold mine tailings in Miyove gold mine (Baradega and Masogwe) in Rwanda were investigated for potential utilization as a source of valuable gold, using the centrifugal separation technique. Results of X-ray diffraction analysis, energy dispersive X-ray spectroscopy, inductively coupled plasma mass spectrometry, inductively coupled plasma–optical emission spectroscopy, and X-ray fluorescence showed that artisanal gold mine tailings samples have significant amounts of gold to justify economical gold extraction opportunity. The gold grades in the ores and artisanal gold mine tailings were in the ranges of 37–152 and 2–7 g t⁻¹, respectively. Quartz was a major phase, with minor impurities in two different types of gold ores and their respective tailings. The beneficiation carried out using centrifugal separation, regarded as an extension of gravity separation, showed gold grades in the range of 535–1515 g t⁻¹ for gold ores and 36–302 g t⁻¹ for artisanal gold mine tailings. The gold recoveries for ores and artisanal gold mine tailings were in the range of 21.8–47.3% and 46.9–63.8%, respectively. The results showed that the centrifugal separation technique was more efficient in boosting gold recovery compared to the present panning approach employed at the site, which sometimes recover as low as 10%. The results suggest that mineralogical characterization of artisanal gold mine tailings allows for the development and design of a suitable methods for improving gold ore beneficiation and artisanal gold mine tailings reprocessing. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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21 pages, 6797 KiB

Open AccessArticle

Stability Evaluation and Structural Parameters Optimization of Stope Based on Area Bearing Theory

by Hao-Yu Qiu, Ming-Qing Huang and Ya-Jie Weng

Minerals 2022, 12(7), 808; https://doi.org/10.3390/min12070808 - 25 Jun 2022

Cited by 8 | Viewed by 2159

Abstract

A reasonable and stable stope structure is the premise of realizing safe mining of underground metal ore. To safely mine the gently inclined medium-thick ore body, stope stability in Bainiuchang Mine was analyzed based on the pillar area bearing theory, and stope stability [...] Read more.

A reasonable and stable stope structure is the premise of realizing safe mining of underground metal ore. To safely mine the gently inclined medium-thick ore body, stope stability in Bainiuchang Mine was analyzed based on the pillar area bearing theory, and stope stability with regard to nine groups of structural parameters was numerically simulated. The results show that the existing stope structural parameters failed to maintain stability requirements and tended to be exposed to the risk of stope collapse. The middle section of the pillar as well as stope roofs and floors are vulnerable due to tensile stress when mining by open stoping, and the compressive stress concentration is prone to occur at the junction of the pillars, stope side walls, roofs and floors. Shear stress contributes little to pillar failure. The reasonable stope structural parameters of open stoping for the gently inclined medium-thick ore body in Bainiuchang mine are optimized using ANSYS numerical simulation: stope height 4.5 m, pillar diameter 4 m, pillar spacing 7 m and pillar row spacing 8 m. The onsite trial shows that the ore recovery rate reaches 82% under these parameters, which also realizes the equilibrium of safety and economy. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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21 pages, 1966 KiB

Open AccessArticle

Variable Weight-Projection Gray Target Evaluation Model of Degree of Protection of Protective Layer Mining

by Bing Qin, Zhanshan Shi, Jianfeng Hao, Bing Liang, Weiji Sun and Feng He

Energies 2022, 15(13), 4654; https://doi.org/10.3390/en15134654 - 25 Jun 2022

Cited by 3 | Viewed by 1414

Abstract

In order to quantitatively evaluate the degree of protection in protective layer mining and provide guidance for the design of a secondary outburst elimination scheme, a variable weight-projection gray target dynamic evaluation model for the effectiveness of protective layer mining is established. The [...] Read more.

In order to quantitatively evaluate the degree of protection in protective layer mining and provide guidance for the design of a secondary outburst elimination scheme, a variable weight-projection gray target dynamic evaluation model for the effectiveness of protective layer mining is established. The improved order relation analysis method was used to determine the subjective weight of each index toward the decision-making goal based on numerical diversity characteristics, and the initial fixed-weight calculation for mixed multi-attribute metrics was processed through the degree of index action. The variable weight function was used to dynamically adjust the fixed weight through the penalty and incentive index methods. Four indexes (gas content, gas pressure, coal seam permeability coefficient, and expansion deformation) were selected, the outburst elimination and anti-reflection were taken as the guide, and the critical value of each index for eliminating burst and the critical value of pressure relief were taken as the positive and negative bullseyes. Based on the variable weight-projection gray target decision model, the distance between the two target centers of each scheme was calculated; at the same time, the variable weight vector changed dynamically with the evaluation scheme to achieve the dynamic quantitative evaluation of the degree of protection. Additionally, compared with the calculation results of fixed weights, it was found that the variable weight-projection bullseye distance can more accurately reflect the dynamic control effect of differences in numerical combinations of multi-attribute indexes in different decision schemes based on the degree of protection of protective layer mining. Taking a mine in PingMei as the engineering background, Ding protected the Wu area, and the degree of protection in the Wu group coal seam reached 116.29%, eliminating the outburst risk of the coal seam. The Wu protected the Ji group coal seam, with the degree of outburst risk in the Ji group being reduced by 14.27, and the Ding + Wu group protected the Ji group coal seam, with the degree of outburst risk of the Ji group being reduced by 20.71%, but not eliminated. The evaluation model quantifies the degree of protection of protective layer mining, and provides a theoretical basis for further assessing whether the working face should strengthen the enhancing permeability or whether it needs to be used in tandem with high-strength outburst elimination methods. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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22 pages, 5860 KiB

Open AccessEssay

Parameter Optimization and Fragmentation Prediction of Fan-Shaped Deep Hole Blasting in Sanxin Gold and Copper Mine

by Bo Ke, Ruohan Pan, Jian Zhang, Wei Wang, Yong Hu, Gao Lei, Xiuwen Chi, Gaofeng Ren and Yuhao You

Minerals 2022, 12(7), 788; https://doi.org/10.3390/min12070788 - 21 Jun 2022

Cited by 10 | Viewed by 2395

Abstract

For San-Xin gold and copper mine, deep blasting large block rate is high resulting in difficulty in transporting the ore out; secondary blasting not only increases blasting costs but is more likely to cause the top and bottom plate of the underground to [...] Read more.

For San-Xin gold and copper mine, deep blasting large block rate is high resulting in difficulty in transporting the ore out; secondary blasting not only increases blasting costs but is more likely to cause the top and bottom plate of the underground to become loose causing safety hazards. Based on the research background of Sanxin gold and copper mine, deep hole blasting parameters were determined by single-hole, variable-hole pitch, and oblique hole blasting tests, further using the inversion method to determine the optimal deep hole blasting parameters. Meanwhile, the PSO-BP neural network method was used to predict the block rate in deep hole blasting. The results of the study showed that the optimal minimum resistance line was 1.24–1.44 m, which was lower than 1.6–1.8 m in the original blasting design, which was one of the reasons for the higher blasting block rate. In addition, the PSO-BP deep hole blasting fragmentation prediction model predicts the block rate of the optimized blasting parameters and predicted a block rate of 6.83% after the optimization of hole network parameters. Its prediction accuracy is high, and the blasting parameter optimization can effectively reduce the block rate. It can reasonably reduce the rate of large pieces produced by blasting, improve blasting efficiency, and save blasting costs for enterprises. The result has wide applicability and can provide solutions for underground mines that also have problems with blasting large block rate. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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16 pages, 4327 KiB

Open AccessArticle

Study on the Improved Method of Wedge Cutting Blasting with Center Holes Detonated Subsequently

by Bing Cheng, Haibo Wang, Qi Zong, Mengxiang Wang, Pengfei Gao and Nao Lv

Energies 2022, 15(12), 4282; https://doi.org/10.3390/en15124282 - 10 Jun 2022

Cited by 5 | Viewed by 2438

Abstract

To acquire a satisfying cutting effect during medium-length hole blasting driving of rock tunnels, an improved wedge cutting blasting method with supplementary blasting of the center holes was proposed. Initially, the cavity forming mechanism of the improved cutting method was analyzed theoretically. The [...] Read more.

To acquire a satisfying cutting effect during medium-length hole blasting driving of rock tunnels, an improved wedge cutting blasting method with supplementary blasting of the center holes was proposed. Initially, the cavity forming mechanism of the improved cutting method was analyzed theoretically. The results suggested that cutting hole blasting could realize the ejection of rock within the range from free face to critical cutting depth, and hence reduce the restraining force of the center hole blasting, and the supplementary blasting of the center holes could further accomplish the expulsion of the residuary rock. Subsequently, simulation of the improved cutting method was implemented to exhibit the stress wave evolution and reveal the stress field distribution. The simulation results indicated that cutting hole blasting could cause the preliminary failure of the residuary rock, and center hole blasting could strengthen the stress field intensity in 1.8–2.5 m in order to aggravate the destruction of the residuary rock. Hence, the residuary rock could be broken into small fragments that were easy to expel out. Finally, a field application experiment was conducted in a coal mine rock tunnel. Using the improved wedge cutting method instead of the conventional wedge cutting method, the full-face blasting driving efficiency was obviously enhanced and the overall blasting driving expense was significantly reduced, which forcefully confirmed the engineering usefulness of the improved wedge cutting method in the medium-length hole blasting driving of rock tunnels. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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21 pages, 4923 KiB

Open AccessArticle

Study of Key Technology of Gob-Side Entry Retention in a High Gas Outburst Coal Seam in the Karst Mountain Area

by Zhenqian Ma, Dongyue Zhang, Yunqin Cao, Wei Yang and Biao Xu

Energies 2022, 15(11), 4161; https://doi.org/10.3390/en15114161 - 6 Jun 2022

Cited by 4 | Viewed by 1773

Abstract

In the gob-side entry retaining by roof cutting (GERRC) technique, pressure is offloaded via directional roof cutting, and a roadway is automatically formed due to the ground pressure and rock-breaking expansion. To improve the application of the theory and technical system of GERRC [...] Read more.

In the gob-side entry retaining by roof cutting (GERRC) technique, pressure is offloaded via directional roof cutting, and a roadway is automatically formed due to the ground pressure and rock-breaking expansion. To improve the application of the theory and technical system of GERRC in the Karst area in Southwest China, this research studies the key technology of GERRC in a high gas outburst coal seam, based on the engineering background of the 39114 working face of the Honglin coal mine. According to the geological conditions of the 39114 working face, by means of formula calculation, UDEC numerical modeling, and on-site drilling peeping, the optimal roof-cutting parameters suitable for the 39114 working face were determined: the roof cutting height was 7 m, the roof cutting angle was 15°, and the spacing of pre-splitting blasting holes was 600 mm. Additionally, the above roof-cutting parameters have achieved good results in the engineering practices of the 39114 transportation roadway, which shows that the technology of GERRC is feasible in high gas outburst mines and achieves the goal of safe and efficient mining. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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20 pages, 2500 KiB

Open AccessArticle

Long- and Short-Term Strategies for Estimation of Hydraulic Fracturing Cost Using Fuzzy Logic

by Hyunjun Im, Hyongdoo Jang, Erkan Topal and Micah Nehring

Minerals 2022, 12(6), 715; https://doi.org/10.3390/min12060715 - 4 Jun 2022

Cited by 5 | Viewed by 2509

Abstract

Over two decades, block caving mining has developed the application of hydraulic fracturing as a preconditioning method. This study aims to estimate hydraulic fracturing costs in block caving operations and suggests the base case of specified costs based on the U.S. Energy Information [...] Read more.

Over two decades, block caving mining has developed the application of hydraulic fracturing as a preconditioning method. This study aims to estimate hydraulic fracturing costs in block caving operations and suggests the base case of specified costs based on the U.S. Energy Information Administration (EIA) report. Furthermore, it applies cavability factors to develop the long- and short-term strategies through the fuzzy inference system. In the long-term strategy, we suggest three possible scenarios for reducing the long-term strategy’s uncertainty by considering the association for the advancement of cost engineering (AACE)’s contingency rate. Moreover, each fuzzy membership function of the three possible redeveloped scenarios was analysed through arithmetic operations over independent/dependent fuzzy numbers for comparing each scenario. The outcome of flexible cost estimation suggested deciding on the scale of infrastructure and ore production by facilitating undercut propagation and controlling block height of block caving operation including additional fragmentation processes. The result of this study also illustrated that systematic fuzzy cost engineering could help estimate the initial stage of budgeting. In addition, through solving the uncertainty of fuzzy calculation values, the project schedule identification is presented by recognising the dependence on each scenario’s common characteristic of the cavability parameter and cost contingency rate. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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16 pages, 14191 KiB

Open AccessArticle

Optimization and Stability of the Bottom Structure Parameters of the Deep Sublevel Stope with Delayed Backfilling

by Mochuan Guo, Yuye Tan, Da Chen, Weidong Song and Shuai Cao

Minerals 2022, 12(6), 709; https://doi.org/10.3390/min12060709 - 1 Jun 2022

Cited by 4 | Viewed by 2052

Abstract

This study analyzes the stability and optimizes the parameters of the bottom structure in sublevel stoping with the delayed backfilling method, improves production efficiency, and increases the ore recovery ratio under the premise of ensuring safe production. Theoretical formulas are used to calculate [...] Read more.

This study analyzes the stability and optimizes the parameters of the bottom structure in sublevel stoping with the delayed backfilling method, improves production efficiency, and increases the ore recovery ratio under the premise of ensuring safe production. Theoretical formulas are used to calculate the stability of the pillar with the bottom structure. Numerical simulation is used to study the stability of muck slash during excavation. Finally, the optimization parameters of the bottom structure are obtained by combining a similar physical experimental model and numerical simulation. The results show that the excavation of the muck slash caused different degrees of deformation at the roof and floor of the roadway. The largest stress occurred at the roadway crossing, whereas the smallest stress was in the middle area. The excavation also caused the secondary stress concentration at the adjacent bottom structure but did not significantly impact its stability. During the mining process, the largest displacement deformation occurred at the roadway crossing, and the influence of mining disturbance on the stability of the bottom structure involves timeliness and periodicity. Considering the recovery ratio, dilution ratio, and stability, the spacing of the extracted ore drift is recommended to be 9 m. This study ensures the stability of the bottom structure in the mining process and obtained reasonable parameters of the extracted ore drift, which provides a scientific way for the mines that use sublevel stoping with the delayed backfilling method. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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6 pages, 217 KiB

Open AccessEditorial

Mining Safety and Sustainability—An Overview

by Longjun Dong, Yanlin Zhao and Wenxue Chen

Sustainability 2022, 14(11), 6570; https://doi.org/10.3390/su14116570 - 27 May 2022

Viewed by 1984

Abstract

The mining industry provides energy and raw material for global economic development and social progress [...] Full article

(This article belongs to the Topic Mining Safety and Sustainability)

17 pages, 3207 KiB

Open AccessArticle

Risk Assessment of Mining Environmental Liabilities for Their Categorization and Prioritization in Gold-Mining Areas of Ecuador

by Bryan Salgado-Almeida, Daniel A. Falquez-Torres, Paola L. Romero-Crespo, Priscila E. Valverde-Armas, Fredy Guzmán-Martínez and Samantha Jiménez-Oyola

Sustainability 2022, 14(10), 6089; https://doi.org/10.3390/su14106089 - 17 May 2022

Cited by 15 | Viewed by 4696

Abstract

Mining environmental liabilities (MEL) are of great concern because of potential risks to ecosystems and human health. In this research, the environmental risk (R_I) related to MEL existing in three artisanal and small-scale gold-mining areas of Ecuador was evaluated. For this [...] Read more.

Mining environmental liabilities (MEL) are of great concern because of potential risks to ecosystems and human health. In this research, the environmental risk (R_I) related to MEL existing in three artisanal and small-scale gold-mining areas of Ecuador was evaluated. For this purpose, data of 167 MEL including landfills, mining galleries, tailing deposits, and mineral processing plants from Macuchi, Tenguel–Ponce Enriquez, and Puyango mining areas, were analyzed. The risk assessment related to the presence of waste deposits was carried out based on the methodology proposed by the Spanish Geological Survey. Moreover, the procedure outlined in the Environmental Risk Assessment Guide of the Ministry of Environment of Peru for nonwaste deposits was applied. The highest R_I values were identified in Puyango and Tenguel–Ponce Enriquez. Thus, they were both categorized as priority control areas requiring intervention and rehabilitation plans. The MEL that require a high level of intervention include waste deposits and mine entrances associated with potentially toxic elements. Moreover, the point risk maps showed that rivers in the studied areas have a potential pollution risk. This study provides risk levels associated with MEL in mining areas from Ecuador. This information could be used for environmental management and pollution mitigation. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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15 pages, 1763 KiB

Open AccessArticle

Research on Factors Affecting Mine Wall Stability in Isolated Pillar Mining in Deep Mines

by Jiang Guo, Xin Cheng, Junji Lu, Yan Zhao and Xuebin Xie

Minerals 2022, 12(5), 623; https://doi.org/10.3390/min12050623 - 13 May 2022

Cited by 2 | Viewed by 2197

Abstract

This study takes the Dongguashan Copper Mine as its engineering background. Based on the mechanical model of the mine wall under the trapezoidal load of the backfill, a comprehensive evaluation index is proposed, and its calculation equation is derived. On this basis, an [...] Read more.

This study takes the Dongguashan Copper Mine as its engineering background. Based on the mechanical model of the mine wall under the trapezoidal load of the backfill, a comprehensive evaluation index is proposed, and its calculation equation is derived. On this basis, an orthogonal test is designed to explore the influence of mining design parameters on mine wall stability. The results show that the width of the mine wall is the main factor affecting its stability, and increasing the width of the mine wall can significantly improve its stability. When the width of the mine wall is kept above 4 m, its stability is better. When the mechanical parameters of the backfill are poor, the mine wall is prone to overturning failure. The width of the mine room has an influence on the multi-directional loading of the mine wall, but the influence on the stability of the mine wall is low. According to the regression equation calculation, the mine wall safety factor is about 1.46 under the design of G5 mining of Dongguashan Line 52, the stability of the mine wall is good after actual mining and the engineering application effect is ideal, which can provide a theoretical basis for the design of isolation pillar mining in deep mines. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 4884 KiB

Open AccessArticle

A Field Study on the Law of Spatiotemporal Development of Rock Movement of Under-Sea Mining, Shandong, China

by Jia Liu, Fengshan Ma, Jie Guo, Guang Li, Yewei Song and Yang Wan

Sustainability 2022, 14(10), 5864; https://doi.org/10.3390/su14105864 - 12 May 2022

Cited by 2 | Viewed by 1641

Abstract

The phenomenon of rock movement in mining areas has always been a difficult problem in mining engineering, especially under complicated geological conditions. Although the backfilling method mitigates the destruction of the surrounding rock, deformation can still exist in the mining area. In order [...] Read more.

The phenomenon of rock movement in mining areas has always been a difficult problem in mining engineering, especially under complicated geological conditions. Although the backfilling method mitigates the destruction of the surrounding rock, deformation can still exist in the mining area. In order to ensure the safety of under-sea mining, it is necessary to study the rock movement laws and the mechanisms. This paper focuses on a settlement analysis of the monitoring data of the No. 55 prospecting profile. By analyzing the shape of the settlement curves, the spatial distribution characteristics of settlements of different mining sublevels are summarized. Additionally, the fractal characteristics of the settlement rate under different space–time conditions are studied. We also discuss the relationship between the fractal phenomenon and the self-organized criticality (SOC) theory. The findings are of great theoretical value for the further study of mining settlements to better understand the physical mechanisms of internal movement and rock mass failures through the fractal law of the settlement. Furthermore, elucidating the rock movement law is an urgent task for the safety of seabed mining. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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15 pages, 5596 KiB

Open AccessArticle

Effect of Loading Rate and Confining Pressure on Strength and Energy Characteristics of Mudstone under Pre-Cracking Damage

by Hanghang Zheng, Zhenqian Ma, Lang Zhou, Dongyue Zhang and Xuchao Liang

Energies 2022, 15(10), 3545; https://doi.org/10.3390/en15103545 - 12 May 2022

Cited by 2 | Viewed by 1423

Abstract

In order to explore the deformation and failure law of deep surrounding rock roadway disturbed by strong dynamic pressure, the triaxial mechanical properties of mudstone samples under pre-cracking damage conditions were tested to study the deformation and failure characteristics and energy evolution mechanism [...] Read more.

In order to explore the deformation and failure law of deep surrounding rock roadway disturbed by strong dynamic pressure, the triaxial mechanical properties of mudstone samples under pre-cracking damage conditions were tested to study the deformation and failure characteristics and energy evolution mechanism in the damage process, under different loading rates and confining pressures. In the mechanical experiment, the specimen is pre-cracked to simulate the damage and failure of surrounding rock during roadway excavation, and the damage degree model of rock specimen is established. The results show that the loading rate and confining pressure have significant effects on the peak strength and energy characteristics of mudstone at the average damage degree of 0.12, and the peak strength increases with the increase in confining pressure and loading rate. Under the same confining pressure, the energy increases first, and then decreases with the increase in loading rate, and the loading rate at the turning point is called the critical loading rate. Under the same confining pressure, the closed stress of mudstone gradually increases with the increase in loading rate, and the closed stress and loading rate show a good linear relationship. Through the fitting relationship, it is found that the fitting correlation coefficient between the closed stress of mudstone and the loading rate is as high as 0.99. The elastic strain energy ratio presents a composite function of exponential function with natural constant e, which is a nonlinear process. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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18 pages, 5735 KiB

Open AccessArticle

Numerical Study on Characteristics of Bedrock and Surface Failure in Mining of Shallow-Buried MCS

by Guangchun Liu, Wenzhi Zhang, Youfeng Zou, Huabin Chai and Yongan Xue

Energies 2022, 15(9), 3446; https://doi.org/10.3390/en15093446 - 9 May 2022

Viewed by 1809

Abstract

Coal is one of the important energy sources for industry. When it is mined, it will cause the destruction of bedrock and surface. However, it is more severe in mining shallow-buried multi coal seams (SBMCS). To better reveal the characteristics of the bedrock [...] Read more.

Coal is one of the important energy sources for industry. When it is mined, it will cause the destruction of bedrock and surface. However, it is more severe in mining shallow-buried multi coal seams (SBMCS). To better reveal the characteristics of the bedrock and surface damage, we have carried out a theoretical analysis, as well as used numerical simulations and field monitoring methods to study the surface and bedrock damage caused by the mining of SBMCS. The characteristics of bedrock and surface failure structure, settlement, and stress distribution were studied and analyzed. The findings show that the collapsed block, formed by the rupture of the overlying stratum, interacts with the surrounding rock to form large cavities and gaps, and the stress concentration occurs between them. The maximum downward vertical concentration stress is about 9.79 MPa. The mining of the lower coal seam can lead to repeated failure of the upper bedrock and goaf. The settlement of bedrock presents gradient change, and the settlement of upper bedrock is large, about 8.0 m, and the maximum settlement is 8.183 m, while that of lower bedrock is small and about 3.5–4.0 m. The weak rock stratum in the bedrock is crushed by the change stress of repeated mining, and formed a broken rock stratum. The cracks in the bedrock develop directly to the ground. On the ground, tensile cracks, compression uplift, stepped cracks, and even collapse pits are easy to cause in mining SBMCS. Affected by repeated mining, the variation of surface vertical stress is complex and disorderly in the middle of the basin, and the variation of horizontal stress is mainly concentrated on the edge of the basin. The maximum stress reaches 100 KPa, and the minimum stress is about 78 KPa. Through theoretical analysis and discussion, the size of the key blocks is directly related to the thickness and strength of the rock stratum. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 1316 KiB

Open AccessArticle

A Triple-Helix Intervention Approach to Direct the Marble Industry towards Sustainable Business in Mexico

by Teodoro Alarcón-Ruíz, María Evelinda Santiago-Jiménez, Loecelia Guadalupe Ruvalcaba-Sánchez, Fabiola Sánchez-Galván, Luis Enrique García-Santamaría and Gregorio Fernández-Lambert

Sustainability 2022, 14(9), 5576; https://doi.org/10.3390/su14095576 - 6 May 2022

Cited by 1 | Viewed by 2895

Abstract

The marble industry in Mexico, similarly to the international market, is going through some problems which are characterized by low productivity performance, inconsistency in management and administrative organization, high raw material waste, and negative social and environmental impact. The methodology used in this [...] Read more.

The marble industry in Mexico, similarly to the international market, is going through some problems which are characterized by low productivity performance, inconsistency in management and administrative organization, high raw material waste, and negative social and environmental impact. The methodology used in this paper is based on a systematic review of the strategies and solutions used to address these problems reported between 2014 and 2021, including the results of the application of in situ surveys to three marble companies in the Mixteca Poblana region. These surveys are collected in this article alongside industry experience to propose, in a structured way, a three-pronged management approach with the aim of directing the marble industry towards a sustainable industry model. The structure of this approach, based on forms of capital and sustainability dimensions, engages governments, companies, schools and society to guide this industrial sector to become a sustainable business, integrating knowledge and experience of the marble industry processes. We recommend adding performance metrics to this approach to assess the value chain of the marble industry. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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19 pages, 4941 KiB

Open AccessArticle

Study on the Distribution Law of Coal Seam Gas and Hydrogen Sulfide Affected by Abandoned Oil Wells

by Xiaoqi Wang, Heng Ma, Xiaohan Qi, Ke Gao and Shengnan Li

Energies 2022, 15(9), 3373; https://doi.org/10.3390/en15093373 - 5 May 2022

Cited by 4 | Viewed by 2118

Abstract

This paper is devoted to solving the problem of how to comprehensively control coal seam gas and hydrogen sulfide in the mining face, distributed from the coal seam in abandoned oil wells in coal mining resource areas. The abandoned oil wells of Ma [...] Read more.

This paper is devoted to solving the problem of how to comprehensively control coal seam gas and hydrogen sulfide in the mining face, distributed from the coal seam in abandoned oil wells in coal mining resource areas. The abandoned oil wells of Ma tan 30 and Ma tan 31 in the No. I0104₁05 working face of the Shuang Ma Coal Mine were taken as examples. Through parameter testing, gas composition analysis, field investigation at the source distribution, and the influence range of gas and hydrogen sulfide in coal seam in the affected range of the abandoned oil wells were studied. The results show that the coal-bearing strata in Shuang Ma coal field belong to the coal–oil coexistence strata, and the emission of H₂S gas in the local area of the working face is mainly affected by closed and abandoned oil wells. Within the influence range of the abandoned oil wells, along the direction of the working face, the concentration of CH₄ and H₂S gas in the borehole increases as you move closer to the coal center, and the two sides of the oil well show a decreasing trend. In the affected area of the abandoned oil well, the distribution of the desorption gas content in coal seam along the center distance of the oil well presents a decreasing trend in power function, particularly the closer the working face is to the center of the oil well. The higher the concentration of CH₄ and H₂S, the lower the concentration when the working face moves further away from the oil well. The influence radius of CH₄ and H₂S gas on the coal seam in the affected area of Ma tan 31 abandoned oil well is over 300 m. The results provide a theoretical basis for further understanding the law of gas and hydrogen sulfide enrichment in the mining face and the design of treatment measures within the influence range of abandoned oil wells. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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19 pages, 3219 KiB

Open AccessArticle

Experimental Study on the Mechanical Characteristics of Saturated Granite under Conventional Triaxial Loading and Unloading Tests

by Zelin Liu and Wei Yi

Sustainability 2022, 14(9), 5445; https://doi.org/10.3390/su14095445 - 30 Apr 2022

Cited by 5 | Viewed by 1881

Abstract

It is essential to study the mechanical properties of saturated rock under different loading and unloading paths for strength calculation, safety assessment and disaster prevention; however, current literature rarely mentions conventional triaxial loading and unloading conditions. To analyze the mechanical properties, strain energy [...] Read more.

It is essential to study the mechanical properties of saturated rock under different loading and unloading paths for strength calculation, safety assessment and disaster prevention; however, current literature rarely mentions conventional triaxial loading and unloading conditions. To analyze the mechanical properties, strain energy evolution characteristics and failure mode, a series of conventional triaxial unloading tests (with axial loading rate v_a of 0.06–6 mm/min and circumferential unloading rate v_u of 0.1–10 MPa/s) and conventional triaxial compression tests were carried out on saturated granite. The test results showed that the damage sources of specimens in the conventional triaxial unloading test were mainly related to circumferential deformation, while in the conventional triaxial compression test, it was related to the axial deformation. Under the same v_a, the confining pressure and axial stress at the failure point decreased with the increase of v_u, and the stress coordinate of the failure point was located outside the conventional triaxial compression envelope of σ₁–σ₃. As v_u increases, except for the variation of circumferential strain energy ΔU_c decreasing slowly, the trend of strain energy changes must be determined together with v_a. As v_a increases, the relationship between the magnitude of each energy changes from ΔU_a > ΔU > ΔU_d > ΔU_e > ΔU_c to ΔU_d > ΔU_a > ΔU > ΔU_e > ΔU_c, while the change of dissipated energy is dominated by v_u and v_a together to become dominated by v_a. In addition, with the increase of v_u and v_a, the damage pattern of the specimen also changes from shear damage in a single shear plane to mixed damage with tensile strain failure and shear plane during which the dilation angle of the specimen increases in total except for v_u = 10 MPa/s, v_a = 0.6 mm/min and 6 mm/min. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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14 pages, 4528 KiB

Open AccessArticle

Low-Cost Electromagnetic Split-Ring Resonator Sensor System for the Petroleum Industry

by Alejandro Rivera-Lavado, Alejandro García-Lampérez, María-Estrella Jara-Galán, Emilio Gallo-Valverde, Paula Sanz and Daniel Segovia-Vargas

Sensors 2022, 22(9), 3345; https://doi.org/10.3390/s22093345 - 27 Apr 2022

Cited by 7 | Viewed by 2204

Abstract

The use of a low-cost split-ring resonator (SRR) passive sensor for the real-time permittivity characterization of hydrocarbon fluids is proposed in this paper. The characterization of the sensor is performed through both full-wave simulation and measurements. Thanks to the analysis of several crude [...] Read more.

The use of a low-cost split-ring resonator (SRR) passive sensor for the real-time permittivity characterization of hydrocarbon fluids is proposed in this paper. The characterization of the sensor is performed through both full-wave simulation and measurements. Thanks to the analysis of several crude samples, the possibility of discrimination between different types of crude and the estimation of several of their properties are demonstrated. Between them, the estimation of sulfur, aromatic hydrocarbons, and salt-water concentrations either in normal ambient conditions or in a high-pressure and high-temperature environment can be mentioned. Experiments were run both at normal ambient conditions and pressures up to 970 bar and temperatures up to 200 °C. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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20 pages, 4472 KiB

Open AccessArticle

Modelling Coal Dust Explosibility of Khyber Pakhtunkhwa Coal Using Random Forest Algorithm

by Amad Ullah Khan, Saad Salman, Khan Muhammad and Mudassar Habib

Energies 2022, 15(9), 3169; https://doi.org/10.3390/en15093169 - 26 Apr 2022

Cited by 11 | Viewed by 2746

Abstract

Coal dust explosion constitutes a significant hazard in underground coal mines, coal power plants and other industries utilising coal as fuel. Knowledge of the explosion mechanism and the factors causing coal explosions is essential to investigate for the identification of the controlling factors [...] Read more.

Coal dust explosion constitutes a significant hazard in underground coal mines, coal power plants and other industries utilising coal as fuel. Knowledge of the explosion mechanism and the factors causing coal explosions is essential to investigate for the identification of the controlling factors for preventing coal dust explosions and improving safety conditions. However, the underlying mechanism involved in coal dust explosions is rarely studied under Artificial Intelligence (AI) based modelling. Coal from three different regions of Khyber Pakhtunkhwa, Pakistan, was tested for explosibility in 1.2 L Hartmann apparatus under various particle sizes and dust concentrations. First, a random forest algorithm was used to model the relationship between inputs (coal dust particle size, coal concentration and gross calorific value (GCV)), outputs (maximum pressure (P_max) and the deflagration index (K_st)). The model reported an R² value of 0.75 and 0.89 for P_max and K_st. To further understand the impact of each feature causing explosibility, the random forest AI model was further analysed for sensitivity analysis by SHAP (Shapley Additive exPlanations). The study revealed that the most critical parameter affecting the explosibility of coal dust were particle size > GCV > concentration for P_max and GCV > Particle size > Concentration for Kst. Mutual interaction SHAP plots of two variables at a time revealed that with <200 gm/L concentration, −73 µm size and a high GCV coal was the most explosive at a high concentration (>400 gm/L), explosibility is relatively lower irrespective of GCV and particle sizes. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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23 pages, 7309 KiB

Open AccessArticle

Study on Crack Classification Criterion and Failure Evaluation Index of Red Sandstone Based on Acoustic Emission Parameter Analysis

by Jiashen Li, Shuailong Lian, Yansen Huang and Chaolin Wang

Sustainability 2022, 14(9), 5143; https://doi.org/10.3390/su14095143 - 24 Apr 2022

Cited by 25 | Viewed by 2553

Abstract

The acoustic emission (AE) characteristics of rock during loading can reflect the law of crack propagation and evolution in the rock. In order to study the fracture mode in the process of rock fracture, the AE characteristics and crack types of red sandstone [...] Read more.

The acoustic emission (AE) characteristics of rock during loading can reflect the law of crack propagation and evolution in the rock. In order to study the fracture mode in the process of rock fracture, the AE characteristics and crack types of red sandstone during fracture were investigated by conducting Brazilian indirect tensile tests (BITT), direct shear tests (DST), and uniaxial compression tests (UCT). The evolution law of AE event rate, RA and AF values, and the distribution law of RA–AF data of red sandstone samples in three test types were analyzed. Based on the kernel density estimation (KDE) function and the coupling AE parameters (RA–AF values) in DST and BITT, the relatively objective dividing line for classifying tensile and shear cracks was discussed, and the dividing line was applied to the analysis of fracture source evolution and the failure precursor of red sandstone. The results show that the dividing line for classifying tensile and shear cracks of red sandstone is AF = 93RA + 75. Under uniaxial compression loading, the fracture source of red sandstone is primarily shear source in the initial phase of loading and tensile source in the critical failure phase, and the number is far greater than shear source. K = AF/(93RA + 75) can be defined as the AE parameter index, and its coefficient of variation CV (k) can be used as the failure judgment index of red sandstone. When CV (k) < 1, it can be considered that red sandstone enters the instability failure phase. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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18 pages, 4592 KiB

Open AccessArticle

Automatic Implementation Algorithm of Pressure Relief Drilling Depth Based on an Innovative Monitoring-While-Drilling Method

by Zheng Wu, Wen-Long Zhang and Chen Li

Sensors 2022, 22(9), 3234; https://doi.org/10.3390/s22093234 - 22 Apr 2022

Cited by 3 | Viewed by 1776

Abstract

An innovative monitoring-while-drilling method of pressure relief drilling was proposed in a previous study, and the periodic appearance of amplitude concentrated enlargement zone in vibration signals can represent the drilling depth. However, there is a lack of a high accuracy model to automatically [...] Read more.

An innovative monitoring-while-drilling method of pressure relief drilling was proposed in a previous study, and the periodic appearance of amplitude concentrated enlargement zone in vibration signals can represent the drilling depth. However, there is a lack of a high accuracy model to automatically identify the amplitude concentrated enlargement zone. So, in this study, a neural network model is put forward based on single-sensor and multi-sensor prediction results. The neural network model consists of one Deep Neural Network (DNN) and four Long Short-Term Memory (LSTM) networks. The accuracy is only 92.72% when only using single-sensor data for identification, while the proposed multiple neural network model could improve the accuracy to being greater than 97.00%. In addition, an optimization method was supplemented to eliminate some misjudgment due to data anomalies, which improved the final accuracy to the level of manual recognition. Finally, the research results solved the difficult problem of identifying the amplitude concentrated enlargement zone and provided the foundation for automatically identifying the drilling depth. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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10 pages, 1955 KiB

Open AccessArticle

Random Forest Slurry Pressure Loss Model Based on Loop Experiment

by Zengjia Wang, Yunpeng Kou, Zengbin Wang, Zaihai Wu and Jiaren Guo

Minerals 2022, 12(4), 447; https://doi.org/10.3390/min12040447 - 6 Apr 2022

Cited by 4 | Viewed by 1908

Abstract

A reasonable arrangement of filling pipelines can solve the problems of low line magnification, a high flow rate, large pipe pressure, etc., in deep well filling slurry transportation. The transportation pressure loss value of filling slurry is the main parameter for the layout [...] Read more.

A reasonable arrangement of filling pipelines can solve the problems of low line magnification, a high flow rate, large pipe pressure, etc., in deep well filling slurry transportation. The transportation pressure loss value of filling slurry is the main parameter for the layout design of filling pipelines. At present, pressure loss data are mainly obtained through the loop pipe experiment, which has problems such as a large amount of labor, high cost, low efficiency, and a limited amount of experimental data. In this paper, combined with a new generation of artificial intelligence technology, the random forest machine learning algorithm is used to analyze and model the experimental data of a loop pipe to predict the pressure loss of slurry transportation. The degree of precision reaches 0.9747, which meets the design accuracy requirements, and it can replace the loop pipe experiment to assist with the filling design. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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12 pages, 4250 KiB

Open AccessArticle

Effect of Chemical Corrosion and Axial Compression on the Dynamic Strength Degradation Characteristics of White Sandstone under Cyclic Impact

by Jinchun Xue, Zhuyu Zhao, Longjun Dong, Jiefang Jin, Yingbin Zhang, Li Tan, Ruoyan Cai and Yihan Zhang

Minerals 2022, 12(4), 429; https://doi.org/10.3390/min12040429 - 31 Mar 2022

Cited by 11 | Viewed by 2320

Abstract

Both chemical corrosion and axial compression impose critical influences on the internal microstructure of rock. Meanwhile, chemical corrosion can change a rock’s mineral composition, which in turn affects the physical and mechanical properties of the rock. To investigate the dynamic strength characteristics of [...] Read more.

Both chemical corrosion and axial compression impose critical influences on the internal microstructure of rock. Meanwhile, chemical corrosion can change a rock’s mineral composition, which in turn affects the physical and mechanical properties of the rock. To investigate the dynamic strength characteristics of white sandstone under the coupling effect of axial load and chemical corrosion, a dynamic and static combined loading test device was adopted for performing cyclic impact tests on white sandstone immersed in chemical solution. The results show that with the increasing number of cycles under the same load, the peak strength of the rock presented a trend of ‘strengthening first and then weakening’. The strength of rock resistance to impact failure reached its maximum when the solution of pH was 7 and axial pressure was 12.6 MPa. Under the same axial pressure, the effect of solution pH on the initial dynamic strength of white sandstone is a normal distribution. Acidic and alkaline environments are harmful to rocks during the initial impact, while neutral environments exert little effect and the pH of the solution influences the particle size of impact crushing particles. In addition, the chemical solution has a significant effect on the deterioration of rock strength during the process of initial impact, and the effect is inconspicuous in the later period. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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16 pages, 5764 KiB

Open AccessArticle

Characteristics of Overburden and Ground Failure in Mining of Shallow Buried Thick Coal Seams under Thick Aeolian Sand

by Guangchun Liu, Youfeng Zou, Wenzhi Zhang and Junjie Chen

Sustainability 2022, 14(7), 4028; https://doi.org/10.3390/su14074028 - 29 Mar 2022

Cited by 3 | Viewed by 4143

Abstract

Mining can lead to overburden failure and ground damage, which are more severe in mining shallow buried thick coal seams (SBTCS) under thick aeolian sand (TAS). We attempted to discover characteristics of mining in this particular geological condition through theoretical derivation and numerical [...] Read more.

Mining can lead to overburden failure and ground damage, which are more severe in mining shallow buried thick coal seams (SBTCS) under thick aeolian sand (TAS). We attempted to discover characteristics of mining in this particular geological condition through theoretical derivation and numerical simulation, and field monitoring. Theoretical methods, combined with numerical simulation and field monitoring methods, reveal the essence of the development and distribution of surface cracks caused by mining SBTCS and depth to thickness ratio (DTR) to be 13.43, less than 15. The findings show that, when mining SBTCS, the overburden breaks down periodically, the initial collapse distance is greater than the collapse step, approximately 55 m on average, and the collapse step is approximately 45 m, on average, in the Daliuta Coal Mine. The collapsed blocks are stacked into goaf and form “masonry beams”, and many cracks and pores are generated between the blocks. The weak stress of the aeolian sand layer causes the movement angle in the aeolian sand layer to be smaller than that in the bedrock, and leads to much sheer, tension and compression failure on the ground, and the main forms of cracks are compression uplift, tensile cracking, shear step. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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18 pages, 22806 KiB

Open AccessArticle

Effect of Freeze–Thaw Cycles on Mechanical and Microstructural Properties of Tailings Reinforced with Cement-Based Material

by Pengchu Ding, Yunbing Hou, Dong Han, Xing Zhang, Shuxiong Cao and Chunqing Li

Minerals 2022, 12(4), 413; https://doi.org/10.3390/min12040413 - 27 Mar 2022

Cited by 9 | Viewed by 2609

Abstract

In China, more than 10,000 Tailings storage facilities (TSF) have been created on the ground surface through mineral mining processes, these TSF occupy a large amount of land. The strength of the tailings is too low to be able to stand on its [...] Read more.

In China, more than 10,000 Tailings storage facilities (TSF) have been created on the ground surface through mineral mining processes, these TSF occupy a large amount of land. The strength of the tailings is too low to be able to stand on its own without strengthening. In order to save land resources and alleviate the damage to the environment caused by mineral mining, it is necessary to reinforce the TSF so that they can store more tailings. China is one of the countries with the largest area of permafrost and seasonal frozen regions, accounting for about 75% of the country’s total land area. The problem can be exacerbated in these regions where the freeze–thaw effect can further degrade the strength of tailings. A review of the literature suggests that there is little research on the mechanical and microstructural properties of tailings reinforced with cement-based materials under freeze–thaw conditions, especially when the tailings are to be discharged to land for sustainable development. This study investigates the effect of freeze–thaw cycles on the mechanical properties and microstructural changes of tailings reinforced with cement-based materials to mitigate environmental hazards. Unconfined compressive strength (UCS) tests, scanning electron microscopic images, X-Ray Diffraction tests, thermogravimetry tests and mercury intrusion porosimetry tests were conducted on samples of tailings. The results from this study show that freeze–thaw cycles reduce the UCS of all the tested samples eventually, but the frozen temperature does not significantly affect the UCS. The larger number of freeze–thaw cycles, the more damage is to the surface morphology and the matrix of the tailings. The results presented in the paper can help engineers and managers to effectively transport the TSF to other locations to minimize environmental hazards to achieve sustainable production of mineral mining processes. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 1885 KiB

Open AccessArticle

Automatic Events Recognition in Low SNR Microseismic Signals of Coal Mine Based on Wavelet Scattering Transform and SVM

by Xin Fan, Jianyuan Cheng, Yunhong Wang, Sheng Li, Bin Yan and Qingqing Zhang

Energies 2022, 15(7), 2326; https://doi.org/10.3390/en15072326 - 23 Mar 2022

Cited by 11 | Viewed by 1829

Abstract

The technology of microseismic monitoring, the first step of which is event recognition, provides an effective method for giving early warning of dynamic disasters in coal mines, especially mining water hazards, while signals with a low signal-to-noise ratio (SNR) usually cannot be recognized [...] Read more.

The technology of microseismic monitoring, the first step of which is event recognition, provides an effective method for giving early warning of dynamic disasters in coal mines, especially mining water hazards, while signals with a low signal-to-noise ratio (SNR) usually cannot be recognized effectively by systematic methods. This paper proposes a wavelet scattering decomposition (WSD) transform and support vector machine (SVM) algorithm for discriminating events of microseismic signals with a low SNR. Firstly, a method of signal feature extraction based on WSD transform is presented by studying the matrix constructed by the scattering decomposition coefficients. Secondly, the microseismic events intelligent recognition model built by operating a WSD coefficients calculation for the acquired raw vibration signals, shaping a feature vector matrix of them, is outlined. Finally, a comparative analysis of the microseismic events and noise signals in the experiment verifies that the discriminative features of the two can accurately be expressed by using wavelet scattering coefficients. The artificial intelligence recognition model developed based on both SVM and WSD not only provides a fast method with a high classification accuracy rate, but it also fits the online feature extraction of microseismic monitoring signals. We establish that the proposed method improves the efficiency and the accuracy of microseismic signals processing for monitoring rock instability and seismicity. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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21 pages, 6927 KiB

Open AccessArticle

Prediction Method for Surface Subsidence of Coal Seam Mining in Loess Donga Based on the Probability Integration Model

by Bingchao Zhao, Yaxin Guo, Xuwei Mao, Di Zhai, Defu Zhu, Yuming Huo, Zedong Sun and Jingbin Wang

Energies 2022, 15(6), 2282; https://doi.org/10.3390/en15062282 - 21 Mar 2022

Cited by 10 | Viewed by 2199

Abstract

The accurate prediction of surface subsidence is a significant foundation for the damage assessment of coal seam mining and ecological environment reclamation in loess donga. However, conventional models are very problematic, and the reliability of prediction is usually low. Therefore, we propose a [...] Read more.

The accurate prediction of surface subsidence is a significant foundation for the damage assessment of coal seam mining and ecological environment reclamation in loess donga. However, conventional models are very problematic, and the reliability of prediction is usually low. Therefore, we propose a method for predicting surface subsidence of coal seam mining in loess donga that is based on the probability integration model, combined with the movement principle of rock and soil layers in the respective study area, and considering the influence of slope stability and additional mining slip on mining subsidence. The feasibility of our new method was verified by a case study in the N1114 working face of the Ningtiaota coal mine (China) that is situated in an area with abundant loess dongas. The results show that slope slippage is the source of error in the prediction of subsidence in loess donga. The prediction idea of “dividing the surface of loess donga into horizontal strata area and slope sub-area, and predicting the subsidence value of the two areas, respectively” is put forward. A method for predicting the subsidence value of two regions is established. First, based on the theory of probability integral and rock formation movement, the probability integral parameters of the horizontal stratum area are determined, and the subsidence basins in the area are superimposed and calculated. Secondly, according to the slope stability and slip principle, the additional displacement of subsidence in the slope area with mining instability coefficient G_cs > 0.87 is calculated. Finally, combined with the subsidence prediction results of the strata area and the slope sub-area, and the position of the slope, the accurate prediction of the surface subsidence in loess donga is realized. Our results show that the agreement between the curves predicted from our calculations and from the measured data are between 88.7–97.8%. The calculated error of the additional displacement of slope mining slip is between 1.0–9.8%. The excellent correlation between the modelled and measured data documents that our method provides, demonstrated a new efficient and valuable tool for the precise prediction of damages induced by mining of underground coal seams in loess donga. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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17 pages, 2337 KiB

Open AccessArticle

Efficient Graphical Algorithm of Sensor Distribution and Air Volume Reconstruction for a Smart Mine Ventilation Network

by Yujiao Liu, Zeyi Liu, Ke Gao, Yuhan Huang and Chengyao Zhu

Sensors 2022, 22(6), 2096; https://doi.org/10.3390/s22062096 - 8 Mar 2022

Cited by 18 | Viewed by 2462

Abstract

The accurate and reliable monitoring of ventilation parameters is key to intelligent ventilation systems. In order to realize the visualization of airflow, it is essential to solve the airflow reconstruction problem using few sensors. In this study, a new concept called independent cut [...] Read more.

The accurate and reliable monitoring of ventilation parameters is key to intelligent ventilation systems. In order to realize the visualization of airflow, it is essential to solve the airflow reconstruction problem using few sensors. In this study, a new concept called independent cut set that depends on the structure of the underlying graph is presented to determine the minimum number and location of sensors. We evaluated its effectiveness in a coal mine owned by Jinmei Corporation Limited (Jinmei Co., Ltd., Shanghai, China). Our results indicated that fewer than 30% of tunnels needed to have wind speed sensors set up to reconstruct the well-posed airflow of all the tunnels (>200 in some mines). The results showed that the algorithm was feasible. The reconstructed air volume of the ventilation network using this algorithm was the same as the actual air volume. The algorithm provides theoretical support for flow reconstruction. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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16 pages, 8727 KiB

Open AccessArticle

Study on Surface Subsidence Characteristics Based on Three-Dimensional Test Device for Simulating Rock Strata and Surface Movement

by Xingyin Ma, Zhiyong Fu, Yurong Li, Pengfei Zhang, Yongqiang Zhao and Guoping Ma

Energies 2022, 15(5), 1927; https://doi.org/10.3390/en15051927 - 7 Mar 2022

Cited by 6 | Viewed by 2192

Abstract

The main functions of a three-dimensional test device for simulating rock formations and surface movement affected by underground coal mining were described in detail, and a series of similar related tests were carried out. The device consisted of an outer frame, a pressurization [...] Read more.

The main functions of a three-dimensional test device for simulating rock formations and surface movement affected by underground coal mining were described in detail, and a series of similar related tests were carried out. The device consisted of an outer frame, a pressurization unit, a pulling unit, and a coal seam simulation portion. Using this test device, supported by monitoring methods such as the three-dimensional laser scanner method, a model test study on the surface subsidence characteristics caused by coal seam mining was carried out. Combined with the field measurements, the transfer law of surface subsidence caused by coal seam mining was revealed, and the whole surface subsidence response process was analyzed. The experimental results show that the subsidence caused by mining disturbances below the coal seam accounts for 79.3% of the total subsidence, which is the dominant factor of the total surface subsidence. After long-term surface observations, surface subsidence can be divided into four stages after coal mining, and the settlement value of the obvious settlement stage accounts for more than 60% of the total settlement value. The above test results fully reflect the feasibility and practicality of the three-dimensional test device to simulate rock strata and surface movement and provide a new experimental research tool that can be used to further study the surface subsidence characteristics and control caused by coal mining. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 2572 KiB

Open AccessArticle

Comprehensive Diagnosis Method of the Health of Tailings Dams Based on Dynamic Weight and Quantitative Index

by Kai Dong, Zhankuan Mi and Dewei Yang

Sustainability 2022, 14(5), 3068; https://doi.org/10.3390/su14053068 - 6 Mar 2022

Cited by 4 | Viewed by 2489

Abstract

As a dangerous source of man-made debris flow with high potential energy, tailings dams can cause huge losses to people’s lives and property downstream once they break, and their safety control problem is particularly prominent. The health diagnosis of tailings dams is a [...] Read more.

As a dangerous source of man-made debris flow with high potential energy, tailings dams can cause huge losses to people’s lives and property downstream once they break, and their safety control problem is particularly prominent. The health diagnosis of tailings dams is a complex and nonlinear problem full of uncertainty. At present, the health diagnosis of tailings dams is mostly qualitative evaluation or quantitative analysis aiming at a single index, so this study puts forward a comprehensive quantitative diagnosis method of tailings dam health based on dynamic weight. Slope stability, deformation stability and seepage stability are taken as project layers, and the diagnosis index system of the tailings dam is constructed. The quantitative methods of diagnosis indexes of project layers are proposed. For the dam slope stability project, the safety factor and the reliability index of tailings dams are determined based on the Monte Carlo method, which can consider the uncertainty of tailings material parameters. For the deformation stability project, the normal operation values of deformation rate and deformation amount are determined by analyzing the in situ observation data and combining them with the numerical simulation results. For the seepage stability project, through the analysis of seepage and stability, the relationship curve between the depth of saturation line and the safety factor of anti-sliding stability is established. The norms method is used to determine the quantitative standards for the diagnosis indexes of the basic layer. Based on the analytical hierarchy process method and the penalty variable weight method, the method of dynamic weight of the project layer index is proposed. The proposed methods are applied to a practical engineering project. The results show that the methods can accurately reflect the health status of tailings dams. This study provides a new method for evaluating the safety of tailings dams. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 5196 KiB

Open AccessArticle

Experimental Study on the Hydroponics of Wetland Plants for the Treatment of Acid Mine Drainage

by Aijing Wu, Yongbo Zhang, Xuehua Zhao, Jiamin Li, Guowei Zhang, Hong Shi, Lina Guo and Shuyuan Xu

Sustainability 2022, 14(4), 2148; https://doi.org/10.3390/su14042148 - 14 Feb 2022

Cited by 7 | Viewed by 3254

Abstract

Acid Mine Drainage (AMD) has become an important issue due to its significant ecological pollution. In this paper, phytoremediation technology and mechanism for AMD were investigated by hydroponic experiments, using six wetland plants (Phragmites australis, Typha orientalis, Cyperus glomeratus, [...] Read more.

Acid Mine Drainage (AMD) has become an important issue due to its significant ecological pollution. In this paper, phytoremediation technology and mechanism for AMD were investigated by hydroponic experiments, using six wetland plants (Phragmites australis, Typha orientalis, Cyperus glomeratus, Scirpus validus, Iris wilsonii, Juncus effusus) as research objects. The results showed that (1) the removal of sulfate from AMD was highest for Juncus effusus (66.78%) and Iris wilsonii (40.74%) and the removal of Mn from AMD was highest for Typha orientalis (>99%) and Phragmites australis (>99%). In addition, considering the growth condition of the plants, Juncus effusus, Iris wilsonii, and Phragmites australis were finally selected as the dominant plants for the treatment of AMD. (2) The removal pathway of pollutants in AMD included two aspects: one part was absorbed by plants, and the other part was removed through hydrolysis and precipitation processes. Our findings provide a theoretical reference for phytoremediation technology for AMD. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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14 pages, 3549 KiB

Open AccessArticle

A Joint Experiment and Discussion for Strength Characteristics of Cemented Paste Backfill Considering Curing Conditions

by Shunman Chen, Wei Wang, Rongfu Yan, Aixiang Wu, Yiming Wang and Erol Yilmaz

Minerals 2022, 12(2), 211; https://doi.org/10.3390/min12020211 - 7 Feb 2022

Cited by 16 | Viewed by 1988

Abstract

As lots of underground mines have been exploited in the past decades, many stope instability and surface subsidence problems are appeared in the underground mines, while the cemented paste backfill (CPB) technology has been applied for more than 40 years, and it can [...] Read more.

As lots of underground mines have been exploited in the past decades, many stope instability and surface subsidence problems are appeared in the underground mines, while the cemented paste backfill (CPB) technology has been applied for more than 40 years, and it can solve these problems. As it is shown that the effect of backfilling is mainly affected by the mechanical properties of the CPB, and there are lots of factors which can influence the strength of the CPB, but the coupled effects of curing conditions has not been reported. In this research, the coupled effects of curing conditions are importantly considered, and the uniaxial compressive strength (UCS) is adopted as the important evaluation index of CPB, then the evolution law of the UCS for CPB are analyzed, also the mathematical strength model of CPB is established. The findings suggest that the relationship between the UCS of CPB and curing stress develops the function of quadratic polynomial with one variable, while the UCS of the CPB shows the power function as the curing temperature increases. Moreover, the established mathematical strength model is verified on the basis of laboratory experiments, the error between the measured UCS and the prediction UCS is less than 15%. It shows that the established strength model of the CPB by considering the curing conditions can predict the UCS very well, it has great significance for the safety design of CPB. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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13 pages, 3056 KiB

Open AccessArticle

Semi-Empirical Time-Dependent Parameter of Shear Strength for Traction Force between Deep-Sea Sediment and Tracked Miner

by Wei Yi and Feng Xu

Sensors 2022, 22(3), 1119; https://doi.org/10.3390/s22031119 - 1 Feb 2022

Cited by 3 | Viewed by 1857

Abstract

Based on our direct shear creep experiment and the direct shear rheological constitutive model, a semi-empirical time-dependent parameter of the shear strength is obtained by Mohr–Coulomb shear strength theory, and different time-dependent traction force calculations between deep-sea sediment and a tracked miner are [...] Read more.

Based on our direct shear creep experiment and the direct shear rheological constitutive model, a semi-empirical time-dependent parameter of the shear strength is obtained by Mohr–Coulomb shear strength theory, and different time-dependent traction force calculations between deep-sea sediment and a tracked miner are conducted by the work-energy principle. The time-dependent traction force calculation under its influencing factors, including the time, track shoe number, and grounding pressure, are analyzed and proved to be valid by the traction force experiment of a single-track shoe. The results show that the time-dependent cohesion force obtained by a semi-empirical way can be easily used to deduce the time-dependent traction force models under the different grounding pressure distributions and applied into deep-sea engineering application conveniently; the verified traction force models by the traction force experiment of a single-track shoe illustrate that traction force under the decrement grounding pressure distribution is the worst among the four kinds of grounding pressure distributions and suggested for evaluating the most unfavorable traction force and calculating the trafficability and stability of the deep-sea tracked miner. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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17 pages, 6681 KiB

Open AccessArticle

Optimization of the Process Parameters of Fully Mechanized Top-Coal Caving in Thick-Seam Coal Using BP Neural Networks

by Minfu Liang, Chengjun Hu, Rui Yu, Lixin Wang, Baofu Zhao and Ziyue Xu

Sustainability 2022, 14(3), 1340; https://doi.org/10.3390/su14031340 - 25 Jan 2022

Cited by 12 | Viewed by 1776

Abstract

The method of fully mechanized top-coal caving mining has become the main method of mining thick-seam coal. The process parameters of fully mechanized caving will affect the recovery rate and gangue content of top coal. Through numerical simulation software, the top-coal recovery rate [...] Read more.

The method of fully mechanized top-coal caving mining has become the main method of mining thick-seam coal. The process parameters of fully mechanized caving will affect the recovery rate and gangue content of top coal. Through numerical simulation software, the top-coal recovery rate and gangue content, under different fully mechanized caving process parameters, were simulated, and the influence law of different fully mechanized caving process parameters on top-coal recovery rate and gangue content was obtained. A decision model for top-coal caving process parameters was established with a BP neural network, and the optimal top-coal caving parameters were obtained for the actual situation of a working face. On this basis, a in-lab similarity simulation test of the particle material was carried out. The results show that the top-coal recovery rate and gangue content were 86.56% and 3.45%, respectively, and the coal caving effect was good. A BP neural network was used to study the decisions optimizing fully mechanized caving process parameters, which effectively improved the decision-making efficiency thereabout and provided a basis for realizing intelligent, fully mechanized caving mining. Full article

(This article belongs to the Topic Mining Safety and Sustainability)

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