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34 pages, 80272 KiB

Open AccessArticle

AFM Image Analysis of the Adsorption of Xanthate and Dialkyl Dithiophosphate on Chalcocite

by Jinhong Zhang and Wei Zhang

Minerals 2022, 12(8), 1018; https://doi.org/10.3390/min12081018 - 13 Aug 2022

Cited by 1 | Viewed by 2988

Abstract

Atomic force microscopy (AFM) has been applied to study the adsorption morphology of various collectors, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX) and Cytec Aerofloat 238 (sodium dibutyl dithiophosphate), on chalcocite in situ in aqueous solutions. The AFM images show [...] Read more.

Atomic force microscopy (AFM) has been applied to study the adsorption morphology of various collectors, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX) and Cytec Aerofloat 238 (sodium dibutyl dithiophosphate), on chalcocite in situ in aqueous solutions. The AFM images show that all these collectors adsorb strongly on chalcocite. Xanthate adsorbs mainly in the form of insoluble cuprous xanthate (CuX), which binds strongly with the mineral surface without being removed by flushing with ethanol alcohol. This xanthate/chalcocite adsorption mechanism is very similar to the one obtained with the xanthate/bornite system; while it is different from the one of the xanthate/chalcopyrite systems, for which oily dixanthogen is the main adsorption product on chalcopyrite surface. On the other hand, dibutyl dithiophosphate adsorbs on chalcocite in the form of hydrophobic patches, which can be removed by rinsing with ethanol alcohol. AFM images show that the adsorption of collectors increases with increasing adsorption time and collectors’ concentration. In addition, increasing the solution pH to 10 does not prevent the adsorption of xanthate and Aerofloat 238 on chalcocite and the result is in line with the fact that chalcocite floats well in a wide pH range up to 12 with xanthate and dialkyl dithiophosphate being used as collectors. The blending collectors study shows that xanthate and dialkyl dithiophosphate can co-adsorb with both insoluble cuprous xanthate and oily Cu(DTP)₂ (Cu dibutyl dithiophosphate) on a chalcocite surface. The present study helps to clarify the flotation mechanism of chalcocite in industry practice using xanthate and dialkyl dithiophosphate as collectors. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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13 pages, 3777 KiB

Open AccessArticle

Boron Impurity Deposition on a Si(100) Surface in a SiHCl₃-BCl₃-H₂ System for Electronic-Grade Polysilicon Production

by Qinghong Yang, Fengyang Chen, Lin Tian, Jianguo Wang, Ni Yang, Yanqing Hou, Lingyun Huang and Gang Xie

Minerals 2022, 12(5), 651; https://doi.org/10.3390/min12050651 - 21 May 2022

Cited by 4 | Viewed by 2336

Abstract

A study of boron impurities deposited on a Si(100) surface in a SiHCl₃-BCl₃-H₂ system is reported in this paper, using periodic density functional theory with generalized gradient approximation (GGA). The results show that the discrete distances of BCl [...] Read more.

A study of boron impurities deposited on a Si(100) surface in a SiHCl₃-BCl₃-H₂ system is reported in this paper, using periodic density functional theory with generalized gradient approximation (GGA). The results show that the discrete distances of BCl₃ and SiHCl₃ from the surface of the Si(100) unit cell are 1.873 Å and 2.340 Å, respectively, and the separation energies are −35.2549 kcal/mol and −10.64 kcal/mol, respectively. BCl₃ and SiHCl₃ are mainly adsorbed on the surface of the Si(100) unit cell in particular molecular orientations: the positive position and the hydrogen bottom-two-front position from the analysis of the bond length change and adsorption energy. The adsorption of SiHCl₃ and BCl₃ is accompanied by a charge transfer from the molecule to the surface of the unit cell of 0.24 and 0.29 eV, respectively. BCl₃ reacts more readily than SiHCl₃ with the Si(100) surface, resulting in the deposition of boron impurities on the polysilicon surface. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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15 pages, 5171 KiB

Open AccessArticle

Assessment of Operational Effectiveness of Innovative Circuit for Production of Crushed Regular Aggregates in Particle Size Fraction 8–16 mm

by Tomasz Gawenda, Agata Stempkowska, Daniel Saramak, Dariusz Foszcz, Aldona Krawczykowska and Agnieszka Surowiak

Minerals 2022, 12(5), 634; https://doi.org/10.3390/min12050634 - 17 May 2022

Cited by 3 | Viewed by 1781

Abstract

The purpose of this paper is to analyze a modern and unique technological system producing common aggregates at the Imielin Dolomite Mine. The installation was built on the basis of inventions of AGH UST and consists of an impact crusher, innovative screens WSR [...] Read more.

The purpose of this paper is to analyze a modern and unique technological system producing common aggregates at the Imielin Dolomite Mine. The installation was built on the basis of inventions of AGH UST and consists of an impact crusher, innovative screens WSR and WSL, light fraction separator SEL and hard fraction separator SET, low-pressure hydrocyclone NHC and infrastructure. The study was carried out on the crusher and screen on the example of production of aggregates with grain size 8–16 mm from dolomite, granite, limestone, sandstone, and gravel. The results showed that cubic aggregates with a low content of irregular grains of less than 1% can be produced in this technological system. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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15 pages, 3184 KiB

Open AccessArticle

An Experimental Study of Pressure Drop Characteristics and Flow Resistance Coefficient in a Fluidized Bed for Coal Particle Fluidization

by Jian Peng, Wei Sun, Le Xie, Haisheng Han and Yao Xiao

Minerals 2022, 12(3), 289; https://doi.org/10.3390/min12030289 - 25 Feb 2022

Cited by 3 | Viewed by 4317

Abstract

Liquid–solid fluidized beds have a wide range of applications in metallurgical processing, mineral processing, extraction, and wastewater treatment. Great interest on their flow stability and heterogeneous fluidization behaviors has been aroused in research. In this study, various fluidization experiments were performed by adjusting [...] Read more.

Liquid–solid fluidized beds have a wide range of applications in metallurgical processing, mineral processing, extraction, and wastewater treatment. Great interest on their flow stability and heterogeneous fluidization behaviors has been aroused in research. In this study, various fluidization experiments were performed by adjusting the operating conditions of particle size, particle density, and liquid superficial velocity. For each case, the steady state of liquid–solid fluidization was obtained, and the bed expansion height and pressure drop characteristics were analyzed. The time evolution of pressure drop at different bed heights can truly reflect the liquid–solid heterogeneous fluidization behaviors that are determined by operating conditions. With the increase in superficial liquid velocity, three typical fluidization stages were observed. Accordingly, the flow resistance coefficient was obtained based on the experimental data of bed expansion height and pressure drop. The flow resistance coefficient experiences a decrease with the increase in the modified particle Reynolds number and densimetric Froude number. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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14 pages, 5692 KiB

Open AccessArticle

Preparation of Antimony Sulfide and Enrichment of Gold by Sulfuration–Volatilization from Electrodeposited Antimony

by Wei Wang, Shuai Wang, Jia Yang, Chengsong Cao, Kanwen Hou, Lixin Xia, Jun Zhang, Baoqiang Xu and Bin Yang

Minerals 2022, 12(2), 264; https://doi.org/10.3390/min12020264 - 19 Feb 2022

Cited by 8 | Viewed by 3874

Abstract

Electrodeposited antimony can be treated with sulfuration–volatilization technology, which causes antimony to volatilize in the form of antimony sulfide. During this process, gold is enriched in the residue, thereby realizing the value-added use of antimony and the recovery of gold. In this study, [...] Read more.

Electrodeposited antimony can be treated with sulfuration–volatilization technology, which causes antimony to volatilize in the form of antimony sulfide. During this process, gold is enriched in the residue, thereby realizing the value-added use of antimony and the recovery of gold. In this study, the thermodynamic conditions of antimony sulfide were analyzed by the Clausius–Clapeyron equation. Moreover, the volatilization behavior of antimony sulfide and the enrichment law of gold were studied by heat volatilization experiments. The effects of the sulfide temperature and volatilization pressure on the separation efficiency of antimony and gold enrichment were investigated. The results demonstrate that the sulfuration rate was the highest, namely 96.06%, when the molar ratio of sulfur to antimony was 3:1, the sulfur source temperature was 400 °C, the antimony source temperature was 550 °C, and the sulfuration time was 30 min. Antimony sulfide prepared under these conditions was volatilized at 800 °C over 2 h at an evaporation pressure of 0.2 atm, and the volatilization rate was the highest, namely 92.81%. Antimony sulfide with a stibnite structure obtained from the sulfuration–volatilization treatment of electrodeposited antimony meets the ideal stoichiometric ratio of sulfur and antimony in Sb₂S₃ (3:2), and gold is enriched in the residue. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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11 pages, 2437 KiB

Open AccessArticle

Efficient Recovery of Vanadium from High-Chromium Vanadium Slag with Calcium-Roasting Acidic Leaching

by Hao Peng, Bing Li, Wenbing Shi and Zuohua Liu

Minerals 2022, 12(2), 160; https://doi.org/10.3390/min12020160 - 28 Jan 2022

Cited by 7 | Viewed by 2554

Abstract

High-chromium vanadium slag (HCVS) is an important by-product generated during the smelting process of high-chromium-vanadium-titanium-magnetite. Direct acid leaching and calcium-roasting acid leaching technology were applied to recover vanadium and chromium from HCVS. The effects of experimental parameters on the leaching process, including concentration [...] Read more.

High-chromium vanadium slag (HCVS) is an important by-product generated during the smelting process of high-chromium-vanadium-titanium-magnetite. Direct acid leaching and calcium-roasting acid leaching technology were applied to recover vanadium and chromium from HCVS. The effects of experimental parameters on the leaching process, including concentration of H₂SO₄, reaction temperature, reaction time, and liquid-to-solid ratio, were investigated. The XRD and UV-Vis DRS results showed that vanadium and chromium existed in low valence with a spinel structure in the HCVS. The Cr-spinel was too stable to leach out; no more than 8% of the chromium could be leached out both in the direct acid leaching process and calcium-roasting acid-leaching process. Most low valence vanadium could be oxidized to high valence with calcium-roasting technology, and the leaching efficiency could be increased from 33.89% to 89.12% at the selected reaction conditions: concentration of H₂SO₄ at 40 vt.%, reaction temperature of 90 °C, reaction time of 3 h, liquid-to-solid ratio of 4:1 mL/g, and stirring rate of 500 rpm. The kinetics analysis indicated that the leaching behavior of vanadium followed the shrinking core model well, and the leaching process was controlled by the surface chemical reaction, with an Ea of 58.95 kJ/mol and 62.98 kJ/mol for direct acid leaching and roasting acid leaching, respectively. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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13 pages, 3152 KiB

Open AccessArticle

Discussion on Criterion of Determination of the Kinetic Parameters of the Linear Heating Reactions

by Kui Li, Wei Zhang, Menglong Fu, Chengzhi Li and Zhengliang Xue

Minerals 2022, 12(1), 81; https://doi.org/10.3390/min12010081 - 10 Jan 2022

Cited by 5 | Viewed by 1528

Abstract

Generally, the linear correlation coefficient is one of the most significant criteria to appraise the kinetic parameters computed from different reaction models. Actually, the optimal kinetic triplet should meet the following two requirements: first, it can be used to reproduce the original kinetic [...] Read more.

Generally, the linear correlation coefficient is one of the most significant criteria to appraise the kinetic parameters computed from different reaction models. Actually, the optimal kinetic triplet should meet the following two requirements: first, it can be used to reproduce the original kinetic process; second, it can be applied to predict the other kinetic process. The aim of this paper is to attempt to prove that the common criteria are insufficient for meeting the above two purposes simultaneously. In this paper, the explicit Euler method and Taylor expansion are presented to numerically predict the kinetic process of linear heating reactions. The mean square error is introduced to assess the prediction results. The kinetic processes of hematite reduced to iron at different heating rates (8, 10 and 18 K/min) are utilized for validation and evaluation. The predicted results of the reduction of Fe₂O₃ → Fe₃O₄ indicated that the inferior linear correlation coefficient did provide better kinetic predicted curves. In conclusion, to satisfy the above two requirements of reproduction and prediction, the correlation coefficient is an insufficient criterion. In order to overcome this drawback, two kinds of numerical prediction methods are introduced, and the mean square error of the prediction is suggested as a superior criterion for evaluation. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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11 pages, 9123 KiB

Open AccessArticle

Performance of TiB₂ Wettable Cathode Coating

by Bo Yang, Ruzhen Peng, Dan Zhao, Ni Yang, Yanqing Hou and Gang Xie

Minerals 2022, 12(1), 27; https://doi.org/10.3390/min12010027 - 24 Dec 2021

Cited by 3 | Viewed by 2729

Abstract

A TiB₂ wettable cathode coating was deposited on a graphite carbon cathode material via atmospheric plasma spraying (APS). The microstructure and phase composition of the TiB₂ coating were analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy [...] Read more.

A TiB₂ wettable cathode coating was deposited on a graphite carbon cathode material via atmospheric plasma spraying (APS). The microstructure and phase composition of the TiB₂ coating were analyzed via scanning electron microscopy (SEM), X-ray diffraction (XRD), and energy-dispersive X-ray spectroscopy (EDS). The wettability and corrosion resistance of the coating were studied in a molten-aluminum electrolytic system. The results showed that the surface of the TiB₂ coating prepared via plasma spraying was flat and that the main phase of the coating was TiB₂. The wettability between the TiB₂ coating and liquid aluminum was better than that between graphite cathode carbon block and liquid aluminum. The abilities of the TiB₂ coating and graphite cathode carbon block to resist sodium (Na) penetration and prevent molten salt corrosion were compared through a corrosion test. The TiB₂ coating was found to have better resistance to Na penetration and better refractory cryolite corrosion resistance than graphite cathode carbon block. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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13 pages, 1650 KiB

Open AccessArticle

Effect of Sodium Metabisulfite on Selective Flotation of Chalcopyrite and Molybdenite

by Yuki Semoto, Gde Pandhe Wisnu Suyantara, Hajime Miki, Keiko Sasaki, Tsuyoshi Hirajima, Yoshiyuki Tanaka, Yuji Aoki and Kumika Ura

Minerals 2021, 11(12), 1377; https://doi.org/10.3390/min11121377 - 7 Dec 2021

Cited by 10 | Viewed by 3594

Abstract

Sodium metabisulfite (MBS) was used in this study for selective flotation of chalcopyrite and molybdenite. Microflotation tests of single and mixed minerals were performed to assess the floatability of chalcopyrite and molybdenite. The results of microflotation of single minerals showed that MBS treatment [...] Read more.

Sodium metabisulfite (MBS) was used in this study for selective flotation of chalcopyrite and molybdenite. Microflotation tests of single and mixed minerals were performed to assess the floatability of chalcopyrite and molybdenite. The results of microflotation of single minerals showed that MBS treatment significantly depressed the floatability of chalcopyrite and slightly reduced the floatability of molybdenite. The results of microflotation of mixed minerals demonstrated that the MBS treatment could be used as a selective chalcopyrite depressant in the selective flotation of chalcopyrite and molybdenite. Furthermore, the addition of diesel oil or kerosene could significantly improve the separation efficiency of selective flotation of chalcopyrite and molybdenite using MBS treatment. A mechanism based on X-ray photoelectron spectroscopy analysis results is proposed in this study to explain the selective depressing effect of MBS on the flotation of chalcopyrite and molybdenite. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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13 pages, 4147 KiB

Open AccessArticle

Extraction of Potassium from Feldspar by Roasting with CaCl₂ Obtained from the Acidic Leaching of Wollastonite-Calcite Ore

by Tülay Türk, Zeynep Üçerler, Fırat Burat, Gülay Bulut and Murat Olgaç Kangal

Minerals 2021, 11(12), 1369; https://doi.org/10.3390/min11121369 - 3 Dec 2021

Cited by 11 | Viewed by 5193

Abstract

Potassium, which is included in certain contents in the structure of K-feldspar minerals, has a very important function in the growth of plants. Turkey hosts the largest feldspar reserves in the world and is by far the leader in feldspar mining. The production [...] Read more.

Potassium, which is included in certain contents in the structure of K-feldspar minerals, has a very important function in the growth of plants. Turkey hosts the largest feldspar reserves in the world and is by far the leader in feldspar mining. The production of potassium salts from local natural sources can provide great contributions both socially and economically in the agriculture industry along with glass production, cleaning materials, paint, bleaching powders, and general laboratory purposes. In this study, potassium extraction from K-feldspar ore with an 8.42% K₂O content was studied using chloridizing (CaCl₂) roasting followed by water leaching. Initially, to produce wollastonite and calcite concentrates, froth flotation tests were conducted on wollastonite-calcite ore after comminution. Thus, wollastonite and calcite concentrates with purities of 99.4% and 91.96% were successfully produced. Then, a calcite concentrate was combined with hydrochloric acid (HCl) under optimal conditions of a 1 mol/L HCl acid concentration, a 60 °C leaching temperature, and a 10 min leaching time to produce CaCl₂. To bring out the importance of roasting before the dissolution process, different parameters such as roasting temperature, duration, and feldspar—CaCl₂ ratios were tested. Under optimal conditions (a 900 °C roasting temperature, a 60 min duration, and a 1:1.5 feldspar—CaCl₂ ratio), 98.6% of the potassium was successfully extracted by the water leaching process described in this article. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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12 pages, 6460 KiB

Open AccessArticle

Effect of Magnesium on the Hydrophobicity of Sphalerite

by Gloria I. Dávila-Pulido, Adrián A. González-Ibarra, Mitzué Garza-García and Danay A. Charles

Minerals 2021, 11(12), 1359; https://doi.org/10.3390/min11121359 - 1 Dec 2021

Cited by 3 | Viewed by 2662

Abstract

The use of untreated recycled water has negative effects in the flotation of zinc sulfide ores due to the presence of dissolved species, such as magnesium and calcium. Although it has been found that magnesium is a more potent depressant than calcium, it [...] Read more.

The use of untreated recycled water has negative effects in the flotation of zinc sulfide ores due to the presence of dissolved species, such as magnesium and calcium. Although it has been found that magnesium is a more potent depressant than calcium, it has not been investigated in this role or for the effect of adding sodium carbonate. The results of an investigation to evaluate the effect of magnesium on the hydrophobicity of Cu-activated sphalerite conditioned with Sodium Isopropyl Xanthate (SIPX) are presented. Zeta potential of natural and Cu-activated sphalerite as a function of the conditioning pH and Cu(II) concentration, respectively, was first evaluated. Later, the effect of pH and presence of magnesium on the contact angle of Cu-activated sphalerite conditioned with SIPX was studied; it was also evaluated the effect of sodium carbonate to counteract the effect of magnesium. Cu-activation enhances the zeta potential of sphalerite up to a concentration of 5 mg/L. Contact angle tests, thermodynamic simulation, and surface analysis showed that magnesium hydroxide precipitates on the sphalerite surface at pH 9.6, decreasing its hydrophobicity. Addition of sodium carbonate as alkalinizing agent precipitates the magnesium in the form of a species that remained dispersed in the bulk solution, favoring the contact angle of Cu-activated sphalerite and, consequently, its hydrophobicity. It is concluded that the use of sodium carbonate as alkalinizing agent favors the precipitation of magnesium as hydromagnesite (Mg₅(OH)₂(CO₃)₄∙4H₂O) instead of hydroxide allowing the recovery of sphalerite. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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15 pages, 4292 KiB

Open AccessArticle

Hydrometallurgical Treatment of Converter Dust from Secondary Copper Production: A Study of the Lead Cementation from Acetate Solution

by Martina Laubertová, Alexandra Kollová, Jarmila Trpčevská, Beatrice Plešingerová and Jaroslav Briančin

Minerals 2021, 11(12), 1326; https://doi.org/10.3390/min11121326 - 27 Nov 2021

Cited by 3 | Viewed by 3487

Abstract

The subject of interest in this study was lead cementation with zinc from solution after conventional agitate acidic leaching of converter dust from secondary copper production. The kinetics of lead cementation from an acid solution of lead acetate using zinc powder was studied. [...] Read more.

The subject of interest in this study was lead cementation with zinc from solution after conventional agitate acidic leaching of converter dust from secondary copper production. The kinetics of lead cementation from an acid solution of lead acetate using zinc powder was studied. The optimal cementation conditions for removing lead from the solution were determined to have a stirring intensity of 300 rpm, a zinc particle size distribution <0.125–0.4> mm and an ambient temperature. Under these conditions, an almost 90% efficiency in removing lead from solution was achieved. The cementation precipitate contains Pb, and a certain amount of Cu. Lead is present in the cementation precipitate in the PbO, Pb₅O₈ and Pb(Cu₂O₂) phases. The solution after cementation was also refined from copper. The solution can be used for further processing in order to obtain a marketable Zn-based product. The resulting cementation precipitate can be further processed and modified to obtain a lead-based product. A kinetic study of the process of lead cementation from solution was also carried out. Based on experimental measurements, the value of apparent activation energy (Ea) which was found to be ~18.66 kJ·mol⁻¹, indicates that this process is diffusion controlled in the temperature range 293–333 K. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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11 pages, 3925 KiB

Open AccessArticle

The Alkaline Fusion-Hydrothermal Synthesis of Blast Furnace Slag-Based Zeolite (BFSZ): Effect of Crystallization Time

by Changxin Li, Xiang Li, Qingwu Zhang, Li Li and Shuai Wang

Minerals 2021, 11(12), 1314; https://doi.org/10.3390/min11121314 - 25 Nov 2021

Cited by 4 | Viewed by 1783

Abstract

Blast furnace slag (BFS) is usually regarded as a by-product of the steel industry, which can be utilized as raw material for preparing BFS-based zeolite (BFSZ). In this study, BFSZ was successfully prepared from BFS using alkaline fusion-hydrothermal synthesis. Via the analyses by [...] Read more.

Blast furnace slag (BFS) is usually regarded as a by-product of the steel industry, which can be utilized as raw material for preparing BFS-based zeolite (BFSZ). In this study, BFSZ was successfully prepared from BFS using alkaline fusion-hydrothermal synthesis. Via the analyses by XRD, SEM, EDX, XRF, FT-IR, elemental mapping and BET/BJH methods, BFSZ crystallization was almost complete at 6 h. With a further increase of crystallization time to 8 h, no significant effect on the formation of crystalline phase was found. Meanwhile, the zeolite content Si/Al (Na/Al) molar ratio was highly affected by crystallization time. The main component of BFSZ prepared at 6 h is cubic crystal with developed surface, with particle size around 2 μm. Moreover, further increasing the crystallization time will not significantly influence the size and morphology of BFSZ product. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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14 pages, 6310 KiB

Open AccessArticle

Detoxification of Arsenic-Containing Copper Smelting Dust by Electrochemical Advanced Oxidation Technology

by Meng Li, Junfan Yuan, Bingbing Liu, Hao Du, David Dreisinger, Yijun Cao and Guihong Han

Minerals 2021, 11(12), 1311; https://doi.org/10.3390/min11121311 - 24 Nov 2021

Cited by 3 | Viewed by 2699

Abstract

A large amount of arsenic-containing solid waste is produced in the metallurgical process of heavy nonferrous metals (copper, lead, and zinc). The landfill disposal of these arsenic-containing solid waste will cause serious environmental problems and endanger people’s health. An electrochemical advanced oxidation experiment [...] Read more.

A large amount of arsenic-containing solid waste is produced in the metallurgical process of heavy nonferrous metals (copper, lead, and zinc). The landfill disposal of these arsenic-containing solid waste will cause serious environmental problems and endanger people’s health. An electrochemical advanced oxidation experiment was carried out with the cathode modified by adding carbon black and polytetrafluoroethylene (PTFE) emulsion. The removal rate of arsenic using advanced electrochemical oxidation with the modified cathode in 75 g/L NaOH at 25 °C for 90 min reached 98.4%, which was significantly higher than 80.69% of the alkaline leaching arsenic removal process. The use of electrochemical advanced oxidation technology can efficiently deal with the problem of arsenic-containing toxic solid waste, considered as a cleaner and efficient method. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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13 pages, 2621 KiB

Open AccessArticle

Effect of Basicity on the Sulfur Precipitation and Occurrence State in Kambara Reactor Desulfurization Slag

by Renlin Zhu, Jianli Li, Jiajun Jiang, Yue Yu and Hangyu Zhu

Minerals 2021, 11(9), 977; https://doi.org/10.3390/min11090977 - 8 Sep 2021

Cited by 3 | Viewed by 2048

Abstract

Kambara Reactor (KR) desulfurization slag used as slag-making material for converter smelting can promote early slag melting in the initial stage and improve the efficiency of dephosphorization. However, its direct utilization as a slagging material can increase the sulfur content in molten steel [...] Read more.

Kambara Reactor (KR) desulfurization slag used as slag-making material for converter smelting can promote early slag melting in the initial stage and improve the efficiency of dephosphorization. However, its direct utilization as a slagging material can increase the sulfur content in molten steel since KR desulfurization slag contains 1~2.5% sulfur. Therefore, this research focuses on the effect of basicity on the precipitation behavior and occurrence state of sulfur in KR desulfurization slag in order to provide an academic reference for the subsequent removal of sulfur from slag through an oxidizing atmosphere. The solidification process of slag was simulated by the Factsage8.0. The slag samples were analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the amount of CaS grains was analyzed using Image-ProPlus6.0 software. The thermodynamic calculation showed that the crystallization temperature of CaS in the molten slag gradually decreased with the increase in basicity, and the CaS crystals in the molten slag mainly existed in the matrix phase and at the silicate grain boundaries. A large number of CaS grains were precipitated along the silicate grain boundary in low-basicity (R = 2.5 and 3.0) slags and fewer CaS grains were precipitated along the silicate grain boundary, while the CaS grain density in the matrix phase was higher in the high-basicity (R = 3.5, 4.0, 4.5) slag. With the increase in basicity, the number of CaS grains gradually decreased, and the CaS grain sizes in slag sample increased gradually. The sulfur in the synthetic slag was in the form of CaS crystals and the amorphous phase, and the content of amorphous sulfur gradually increased with increasing basicity. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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13 pages, 3577 KiB

Open AccessArticle

Maintenance of the Metastable State and Induced Precipitation of Dissolved Neodymium (III) in an Na₂CO₃ Solution

by Youming Yang, Xiaolin Zhang, Kaizhong Li, Li Wang, Fei Niu, Donghui Liu and Yuning Meng

Minerals 2021, 11(9), 952; https://doi.org/10.3390/min11090952 - 31 Aug 2021

Cited by 2 | Viewed by 2061

Abstract

Rare earths dissolved in carbonate solutions exhibit a metastable state. During the period of metastability, rare earths dissolve stably without precipitation. In this paper, neodymium was chosen as a representative rare earth element. The effects of additional NaCl and CO₂ on the [...] Read more.

Rare earths dissolved in carbonate solutions exhibit a metastable state. During the period of metastability, rare earths dissolve stably without precipitation. In this paper, neodymium was chosen as a representative rare earth element. The effects of additional NaCl and CO₂ on the metastable state were investigated. The metastable state can be controlled by adding NaCl to the Na₂CO₃ solution. Molecular dynamics studies indicated that the Cl⁻ provided by the additional NaCl partially occupied the coordination layer of Nd³⁺, causing the delayed formation of neodymium carbonate precipitation. In addition, the additional NaCl decreased the concentration of free carbonate in the solution, thereby reducing the behavior of free contact between carbonate and Nd, as well as resulting in the delay of Nd precipitate formation. Consequently, the period of the metastable state was prolonged in the case of introduction of NaCl. However, changing the solution environment by introducing CO₂ can destroy the metastable state rapidly. Introduction of CO₂ gas significantly decreased the CO₃²⁻ content in the solution and increased its activity, resulting in an increase of the free CO₃²⁻ concentration of the solution in the opposite direction. As a result, the precipitation process was accelerated and the metastable state was destroyed. It was possible to obtain a large amount of rare earth carbonate precipitation in a short term by introducing CO₂ into the solution with dissolved rare earths in the metastable state to achieve rapid separation of rare earths without introducing other precipitants during the process. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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24 pages, 8836 KiB

Open AccessFeature PaperArticle

An Investigation of the Adsorption of Xanthate on Bornite in Aqueous Solutions Using an Atomic Force Microscope

by Jinhong Zhang

Minerals 2021, 11(8), 906; https://doi.org/10.3390/min11080906 - 21 Aug 2021

Cited by 3 | Viewed by 3001

Abstract

An atomic force microscope (AFM) was applied to study of the adsorption of xanthate on bornite surfaces in situ in aqueous solutions. AFM images showed that xanthate, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX), adsorbed strongly on bornite, and the [...] Read more.

An atomic force microscope (AFM) was applied to study of the adsorption of xanthate on bornite surfaces in situ in aqueous solutions. AFM images showed that xanthate, i.e., potassium ethyl xanthate (KEX) and potassium amyl xanthate (PAX), adsorbed strongly on bornite, and the adsorbate bound strongly with the mineral surface without being removed by flushing with ethanol alcohol. The AFM images also showed that the adsorption increased with the increased collector concentration and contact time. Xanthate adsorbed on bornite in a similar manner when the solution pH changed to pH 10. The AFM force measurement results showed that the probe–substrate adhesion increased due to the adsorption of xanthate on bornite. The sharp “jump-in” and “jump-off” points on force curve suggest that the adsorbate is not “soft” in nature, ruling out the existence of dixanthogen, an oily substance. Finally, the ATR-FTIR (attenuated total reflection-Fourier-transform infrared) result confirms that the adsorbate on bornite in xanthate solutions is mainly in the form of insoluble cuprous xanthate (CuX) instead of dixanthogen. This xanthate/bornite adsorption mechanism is very similar to what is obtained with the xanthate/chalcocite system, while it is different from the xanthate/chalcopyrite system, for which oily dixanthogen is the main adsorption product on the chalcopyrite surface. The present study helps clarify the flotation mechanism of bornite in industry practice using xanthate as a collector. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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30 pages, 6044 KiB

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Recent Advancements in Metallurgical Processing of Marine Minerals

by Katarzyna Ochromowicz, Kurt Aasly and Przemyslaw B. Kowalczuk

Minerals 2021, 11(12), 1437; https://doi.org/10.3390/min11121437 - 19 Dec 2021

Cited by 15 | Viewed by 4986

Abstract

Polymetallic manganese nodules (PMN), cobalt-rich manganese crusts (CRC) and seafloor massive sulfides (SMS) have been identified as important resources of economically valuable metals and critical raw materials. The currently proposed mineral processing operations are based on metallurgical approaches applied for land resources. Thus [...] Read more.

Polymetallic manganese nodules (PMN), cobalt-rich manganese crusts (CRC) and seafloor massive sulfides (SMS) have been identified as important resources of economically valuable metals and critical raw materials. The currently proposed mineral processing operations are based on metallurgical approaches applied for land resources. Thus far, significant endeavors have been carried out to describe the extraction of metals from PMN; however, to the best of the authors’ knowledge, it lacks a thorough review on recent developments in processing of CRC and SMS. This paper begins with an overview of each marine mineral. It is followed by a systematic review of common methods used for extraction of metals from marine mineral deposits. In this review, we update the information published so far in peer-reviewed and technical literature, and briefly provide the future perspectives for processing of marine mineral deposits. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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21 pages, 3403 KiB

Open AccessReview

Titanium: An Overview of Resources and Production Methods

by Mohammed El Khalloufi, Olivier Drevelle and Gervais Soucy

Minerals 2021, 11(12), 1425; https://doi.org/10.3390/min11121425 - 16 Dec 2021

Cited by 40 | Viewed by 27503

Abstract

For several decades, the metallurgical industry and the research community worldwide have been challenged to develop energy-efficient and low-cost titanium production processes. The expensive and energy-consuming Kroll process produces titanium metal commercially, which is highly matured and optimized. Titanium’s strong affinity for oxygen [...] Read more.

For several decades, the metallurgical industry and the research community worldwide have been challenged to develop energy-efficient and low-cost titanium production processes. The expensive and energy-consuming Kroll process produces titanium metal commercially, which is highly matured and optimized. Titanium’s strong affinity for oxygen implies that conventional Ti metal production processes are energy-intensive. Over the past several decades, research and development have been focusing on new processes to replace the Kroll process. Two fundamental groups are categorized for these methods: thermochemical and electrochemical. This literature review gives an insight into the titanium industry, including the titanium resources and processes of production. It focuses on ilmenite as a major source of titanium and some effective methods for producing titanium through extractive metallurgy processes and presents a critical view of the opportunities and challenges. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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15 pages, 3947 KiB

Open AccessReview

Leaching Chalcocite in Chloride Media—A Review

by Norman Toro, Carlos Moraga, David Torres, Manuel Saldaña, Kevin Pérez and Edelmira Gálvez

Minerals 2021, 11(11), 1197; https://doi.org/10.3390/min11111197 - 28 Oct 2021

Cited by 8 | Viewed by 3930

Abstract

Chalcocite is the most abundant secondary copper sulfide globally, with the highest copper content, and is easily treated by conventional hydrometallurgical processes, making it a very profitable mineral for extraction. Among the various leaching processes to treat chalcocite, chloride media show better results [...] Read more.

Chalcocite is the most abundant secondary copper sulfide globally, with the highest copper content, and is easily treated by conventional hydrometallurgical processes, making it a very profitable mineral for extraction. Among the various leaching processes to treat chalcocite, chloride media show better results and have a greater industrial boom. Chalcocite dissolution is a two-stage process, the second being much slower than the first. During the second stage, in the first instance, it is possible to oxidize the covellite in a wide range of chloride concentrations or redox potentials (up to 75% extraction of Cu). Subsequently, CuS₂ is formed, which is to be oxidized. It is necessary to work at high concentrations of chloride (>2.5 mol/L) and/or increase the temperature to reach a redox potential of over 650 mV, which in turn decreases the thickness of the elemental sulfur layer on the mineral surface, facilitating chloride ions to generate a better porosity of this. Finally, it is concluded that the most optimal way to extract copper from chalcocite is, during the first stage, to work with high concentrations of chloride (50–100 g/L) and low concentrations of sulfuric acid (0.5 mol/L) at a temperature environment, as other variables become irrelevant during this stage if the concentration of chloride ions in the system is high. While in the second stage, it is necessary to increase the temperature of the system (moderate temperatures) or incorporate a high concentration of some oxidizing agent to avoid the passivation of the mineral. Full article

(This article belongs to the Special Issue Chemical Engineering and Technology in Mineral Processing and Extractive Metallurgy)

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