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14 pages, 2835 KiB

Open AccessArticle

Kinetic Analysis of the Thermal Decomposition of a Synthetic Mercury Jarosite

by Mizraim U. Flores, Iván A. Reyes, Elia G. Palacios, Francisco Patiño, Julio C. Juárez, Martín Reyes, Aislinn M. Teja, Hernán Islas and Emmanuel J. Gutiérrez

Minerals 2019, 9(4), 200; https://doi.org/10.3390/min9040200 - 27 Mar 2019

Cited by 11 | Viewed by 3658

Abstract

Jarosites are widely used in the hydrometallurgical industry of zinc to eliminate iron and other impurities contained in the concentrates. However, these compounds can also incorporate elements of significant environmental concern such as Tl⁺, Hg²⁺, Pb²⁺, Cd [...] Read more.

Jarosites are widely used in the hydrometallurgical industry of zinc to eliminate iron and other impurities contained in the concentrates. However, these compounds can also incorporate elements of significant environmental concern such as Tl⁺, Hg²⁺, Pb²⁺, Cd²⁺, Cr(VI), and As(V). In this work, the characterization of a synthetic mercury jarosite and its thermal decomposition kinetics are reported. XRD and FTIR analyses confirm that a mercury jarosite—Hg_0.40(H₃O)_0.2]Fe_2.71(SO₄)_2.17(OH)_4.79(H₂O)_0.44—was successfully synthesized. Four mass loss events were observed by thermogravimetric analysis at 290 °C, 365 °C, 543 °C, and 665 °C. The third event corresponds to mercury decomposition into mercury oxide, whilst the forth is related to the jarosite to hematite transformation determined by X-ray diffraction starting at around 600 °C. According to the kinetic parameters (activation energy and frequency factor) of the thermal decomposition process, the fourth stage required the highest energy (Ea = 234.7 kJ∙mol⁻¹), which corresponds to elimination of sulfur and oxygen from the jarosite lattice. Results show that jarosite-type compounds have the capability to incorporate heavy metals into their structure, retaining them even at high temperatures. Therefore, they can be used as a remediation strategy for heavy metals, such as mercury and others elements of environmental concern. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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15 pages, 4694 KiB

Open AccessArticle

Cleaner Extraction of Lead from Complex Lead-Containing Wastes by Reductive Sulfur-Fixing Smelting with Low SO₂ Emission

by Yun Li, Shenghai Yang, Wenrong Lin, Pekka Taskinen, Jing He, Yuejun Wang, Junjie Shi, Yongming Chen, Chaobo Tang and Ari Jokilaakso

Minerals 2019, 9(2), 119; https://doi.org/10.3390/min9020119 - 17 Feb 2019

Cited by 11 | Viewed by 4329

Abstract

A novel and cleaner process for lead and silver recycling from multiple lead-containing wastes, e.g., lead ash, lead sludge, lead slag, and ferric sludge, by reductive sulfur-fixing smelting was proposed. In this process, coke and iron-containing wastes were employed as reductive agent and [...] Read more.

A novel and cleaner process for lead and silver recycling from multiple lead-containing wastes, e.g., lead ash, lead sludge, lead slag, and ferric sludge, by reductive sulfur-fixing smelting was proposed. In this process, coke and iron-containing wastes were employed as reductive agent and sulfur-fixing agent, respectively. A Na₂CO₃-Na₂SO₄ mixture was added as flux. The feasibility of this process was detected from thermodynamic and experimental perspectives. The influence of Fe/SiO₂ and CaO/SiO₂, composition of the molten salt, coke addition, smelting temperature, and smelting time on direct Pb recovery and sulfur-fixation efficiency were investigated. The optimal process conditions were determined as follows: W_Coke = 15% W_{Pb wastes},

W_{{Na}_{2} {CO}_{3}} / W_{{Na}_{2} {SO}_{4}}

= 0.7/0.3, Fe/SiO₂ = 1.10, CaO/SiO₂ = 0.30, smelting temperature 1200 °C, and smelting time 2 h, where W represents weight. Under these optimum conditions, 92.4% Pb and 98.8% Ag were directly recovered in crude lead bullion in one step treatment, and total 98.6% sulfur was fixed. The generation and emissions of SO₂ can be avoided. The main phases in ferrous matte obtained were FeS, NaFeS₂, Fe₂Zn₃S₅, and a little entrained Pb. The slag was a FeO-SiO₂-CaO-Na₂O quaternary melt. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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11 pages, 3558 KiB

Open AccessArticle

The Correlation of Roasting Conditions in Selective Potassium Extraction from K-Feldspar Ore

by Mete Tayhan Serdengeçti, Hüseyin Baştürkcü, Fırat Burat and Murat Olgaç Kangal

Minerals 2019, 9(2), 109; https://doi.org/10.3390/min9020109 - 13 Feb 2019

Cited by 21 | Viewed by 5040

Abstract

Feldspar minerals are essential ingredients for the glass and ceramic-glass industries. The potassium element found in certain proportions in the composition of K-feldspar minerals has a fundamental function in the growth of plants. The production of potassium fertilizers is mostly made from the [...] Read more.

Feldspar minerals are essential ingredients for the glass and ceramic-glass industries. The potassium element found in certain proportions in the composition of K-feldspar minerals has a fundamental function in the growth of plants. The production of potassium fertilizers is mostly made from the soluble minerals, which are located in lakes. Despite having a huge area of use in the agriculture industry, the reserves of these salts are limited and not evenly distributed in the earth’s crust. Due to the high availability of feldspar reserves in the earth’s crust, the production of potential potassium salts can provide a wide range of social and economic benefits. In this study, potassium extraction from a feldspar ore, which contained microcline, albite, muscovite, and quartz, was studied using chloridizing (CaCl₂) roasting followed by leaching. Direct leaching experiments were also performed on the sample by adapting various solvents. To emphasize the importance of roasting before the dissolution process, different parameters such as particle size, roasting temperature, and duration, as well as the feldspar/CaCl₂ ratio, were tested. Under the optimum conditions (i.e., −106 microns, 850 Co, 60 minutes, 1:1.5 feldspar:CaCl₂), 99% of the potassium was successfully extracted from the ore feed. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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16 pages, 2486 KiB

Open AccessArticle

Behavior of Tin and Antimony in Secondary Copper Smelting Process

by Lassi Klemettinen, Katri Avarmaa, Hugh O’Brien, Pekka Taskinen and Ari Jokilaakso

Minerals 2019, 9(1), 39; https://doi.org/10.3390/min9010039 - 12 Jan 2019

Cited by 30 | Viewed by 5796

Abstract

Different types of metal-bearing wastes, such as WEEE (Waste Electrical and Electronic Equipment), are important urban minerals in modern society, and the efficient recycling and reuse of their metal values is of key interest. Pyrometallurgical copper smelting is one of the most prominent [...] Read more.

Different types of metal-bearing wastes, such as WEEE (Waste Electrical and Electronic Equipment), are important urban minerals in modern society, and the efficient recycling and reuse of their metal values is of key interest. Pyrometallurgical copper smelting is one of the most prominent ways of treating WEEE, however, more accurate experimental data is needed regarding the behavior of different elements during each process stage. This article investigates the behavior of tin and antimony, both commonly present as trace elements in electrical and electronic waste, in secondary (i.e., sulfur-free) copper smelting conditions. The experiments were conducted in oxygen partial pressure range of 10⁻¹⁰–10⁻⁵ atm, covering the different process steps in copper smelting. The basis of the equilibrium system was metallic copper–iron silicate slag, with the addition of alumina and potassium oxide to account for the presence of these compounds in the actual industrial process. The results showed that the distribution coefficients of both trace metals, L^Cu/slag = [wt % Me]_copper/(wt % Me)_slag, increased significantly as a function of decreasing oxygen pressure, and the addition of basic potassium oxide also had an increasing effect on the distribution coefficient. A brief comparison between EPMA and LA-ICP-MS (electron probe microanalysis and laser ablation–inductively coupled plasma–mass spectrometry), the two in situ analytical techniques used, was also presented and discussed. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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15 pages, 3244 KiB

Open AccessFeature PaperArticle

Thermodynamic Investigation of the Sulphation Roasting of Electric Arc Furnace Dust

by Christopher A. Pickles and Omid Marzoughi

Minerals 2019, 9(1), 18; https://doi.org/10.3390/min9010018 - 27 Dec 2018

Cited by 11 | Viewed by 4394

Abstract

During the remelting of automobile scrap in the electric arc furnace steelmaking process, a dust is generated. This dust contains significant amounts of zinc, iron, and lead and in some cases, copper and nickel. However, the recovery of these metals is difficult, because [...] Read more.

During the remelting of automobile scrap in the electric arc furnace steelmaking process, a dust is generated. This dust contains significant amounts of zinc, iron, and lead and in some cases, copper and nickel. However, the recovery of these metals is difficult, because of the complex chemical and physical characteristics of the dust. Numerous pyrometallurgical, hydrometallurgical and hybrid processes have been devised and tested for metal recovery, but only the Waelz rotary kiln process has achieved significant commercialisation. One potential process, which has received little attention in the literature, is the pyrometallurgical sulphation of the dust. In the present research, a high temperature thermodynamic model has been developed using HSC^® Chemistry 7.1, to investigate the sulphation of the dust. The effects of process parameters on the conversion of the various metals into sulphates were studied. At a temperature of 600 °C, almost one hundred percent of the zinc could be converted into zinc sulphate, while about ninety-five percent of the iron could be retained as hematite. In addition, several low cost, potential sulphating reagents were evaluated. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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15 pages, 4745 KiB

Open AccessArticle

Carbothermic Reduction of Ore-Coal Composite Pellets in a Tall Pellets Bed

by Xin Jiang, Guangen Ding, He Guo, Qiangjian Gao and Fengman Shen

Minerals 2018, 8(12), 550; https://doi.org/10.3390/min8120550 - 27 Nov 2018

Cited by 2 | Viewed by 3916

Abstract

Recently, increasing attention has been paid to alternative ironmaking processes due to the desire for sustainable development. Aiming to develop a new direct reduction technology, the paired straight hearth (PSH) furnace process, the carbothermic reduction of ore-coal composite pellets in a tall pellets [...] Read more.

Recently, increasing attention has been paid to alternative ironmaking processes due to the desire for sustainable development. Aiming to develop a new direct reduction technology, the paired straight hearth (PSH) furnace process, the carbothermic reduction of ore-coal composite pellets in a tall pellets bed was investigated at the lab-scale in the present work. The experimental results show that, under the present experimental conditions, when the height of the pellets bed is 80 mm (16–18 mm each layer, and 5 layers), the optimal amount of carbon to add is C/O = 0.95. Addition of either more or less carbon does not benefit the production of high quality direct reduced iron (DRI). The longer reduction time (60 min) may result in more molten slag in the top layer of DRI, which does not benefit the actual operation. At 50 min, the metallization degree could be up to 85.24%. When the experiment was performed using 5 layers of pellets (about 80 mm in height) and at 50 min duration, the productivity of metallic iron could reach 55.41 kg-MFe/m²·h (or 75.26 kg-DRI/m²·h). Therefore, compared with a traditional shallow bed (one or two layers), the metallization degree and productivity of DRI can be effectively increased in a tall pellets bed. It should be pointed out that the pellets bed and the temperature should be increased simultaneously. The present investigation may give some guidance for the commercial development of the PSH process in the future. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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19 pages, 9738 KiB

Open AccessArticle

Microwave Treatment of Ultramafic Nickel Ores: Heating Behavior, Mineralogy, and Comminution Effects

by Erin R. Bobicki, Qingxia Liu and Zhenghe Xu

Minerals 2018, 8(11), 524; https://doi.org/10.3390/min8110524 - 11 Nov 2018

Cited by 29 | Viewed by 6940

Abstract

Ultramafic nickel ores are difficult to process because they contain serpentine, an anisotropic mineral with a nonspherical morphology and multiple pH-dependent surface charges. Dehydroxylation of serpentine in ultramafic nickel ores by microwave treatment is proposed to improve the processability of these ores. Upon [...] Read more.

Ultramafic nickel ores are difficult to process because they contain serpentine, an anisotropic mineral with a nonspherical morphology and multiple pH-dependent surface charges. Dehydroxylation of serpentine in ultramafic nickel ores by microwave treatment is proposed to improve the processability of these ores. Upon heating, serpentine is converted to olivine, an isotropic mineral that is benign in mineral processing circuits. The microwave heating of two ultramafic nickel ores is explored in this paper, as well as effects on mineralogy and grindability. The first ore was sourced from the Okanogan nickel deposit in Washington State, USA, while the second ore was obtained from the Vale-owned Pipe deposit located in the Thomson Nickel Belt in Manitoba, Canada. The ultramafic nickel ores were found to heat well upon exposure to microwave radiation and the heating behaviors were a function of the imaginary permittivities. The temperatures achieved during microwave treatment were sufficient to dehydroxylate serpentine, and the serpentine content in ultramafic nickel ores was reduced by 63–84%. The grindability of ore with consistent texture (OK ore) improved dramatically with microwave treatment, whereas the grindability of ore with inconsistent texture (Pipe ore) was found to decrease. Pentlandite liberation and specific surface area improved for both ores with microwave treatment. Ultimately, microwave pretreatment did not decrease the energy required for grinding under the conditions studied. However, energy savings may be realized when overall process improvements are considered (e.g., grinding, rheology, flotation, material handling, dewatering and tailings treatment). Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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24 pages, 1965 KiB

Open AccessArticle

Assessing the Similarity of Cyanide-Free Gold Leaching Processes: A Case-Based Reasoning Application

by Maria Leikola, Christian Sauer, Lotta Rintala, Jari Aromaa and Mari Lundström

Minerals 2018, 8(10), 434; https://doi.org/10.3390/min8100434 - 2 Oct 2018

Cited by 5 | Viewed by 4407

Abstract

Hydrometallurgical researchers, and other professionals alike, invest significant amounts of time reading scientific articles, technical notes, and other scientific documents, while looking for the most relevant information for their particular research interest. In an attempt to save the researcher’s time, this study presents [...] Read more.

Hydrometallurgical researchers, and other professionals alike, invest significant amounts of time reading scientific articles, technical notes, and other scientific documents, while looking for the most relevant information for their particular research interest. In an attempt to save the researcher’s time, this study presents an information retrieval tool using case-based reasoning. The tool was built for comparing scientific articles concerning cyanide-free leaching of gold ores/concentrates/tailings. Altogether, 50 cases of experiments were gathered in a case base. 15 different attributes related to the treatment of the raw material and the leaching conditions were selected to compare the cases. The attributes were as follows: Pretreatment, Overall method, Complexant source, Oxidant source, Complexant concentration, Oxidant concentration, Temperature, pH, Redox-potential, Pressure, Materials of construction, Extraction, Extraction rate, Reagent consumption, and Solid-liquid ratio. The resulting retrieval tool (LeachSim) was able to rank the scientific articles according to their similarity with the user’s research interest. Such a tool could eventually aid the user in finding the most relevant information, but not replace thorough understanding and human expertise. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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15 pages, 4902 KiB

Open AccessArticle

A High-Efficiency Approach for the Synthesis of N235-Impregnated Resins and the Application in Enhanced Adsorption and Separation of Vanadium(V)

by Bo Chen, Shenxu Bao, Yimin Zhang and Ruwei Zheng

Minerals 2018, 8(8), 358; https://doi.org/10.3390/min8080358 - 19 Aug 2018

Cited by 12 | Viewed by 3557

Abstract

Trialkylamine (N235)-tributyl phosphate (TBP) impregnated resins (N-TIRs) were prepared, so as to evaluate the effects of the addition of TBP on the preparation and adsorption performance of N235-impregnated resins (NIRs). The results show that TBP can obviously increase the impregnation ratio and shorten [...] Read more.

Trialkylamine (N235)-tributyl phosphate (TBP) impregnated resins (N-TIRs) were prepared, so as to evaluate the effects of the addition of TBP on the preparation and adsorption performance of N235-impregnated resins (NIRs). The results show that TBP can obviously increase the impregnation ratio and shorten the impregnation equilibrium time of the N-TIRs when compared to that of the NIRs (57.73% versus 36.95% and 5 min versus 240 min). It is confirmed that TBP can interact with N235 during the impregnation process, which shorten the adsorption equilibrium time and increases the adsorption capacity of the N-TIRs for V(V) when compared to that of the NIRs (6 h versus 10 h and 50.95 mg·g⁻¹ versus 46.73 mg·g⁻¹). The kinetics fitting results demonstrate that the adsorption of V(V) onto N-TIRs and NIRs all conform to pseudo-second order kinetic model and chemical reaction is the rate-limiting step of the whole adsorption process. In the meanwhile, the reaction constant (K_s) implies that the chemical reaction rate of V(V) with the impregnated extractants in N-TIRs is faster than that in NIRs. The N-TIRs present higher stability and selectivity than NIRs. This study manifests that the addition of a secondary reagent may be a potential and novel technique on the preparation of SIRs and the enhancement of adsorption and separation for ions. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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18 pages, 8901 KiB

Open AccessArticle

The Effects of Sodium Ions, Phosphorus, and Silicon on the Eco-Friendly Process of Vanadium Precipitation by Hydrothermal Hydrogen Reduction

by Guobin Zhang, Yimin Zhang and Shenxu Bao

Minerals 2018, 8(7), 294; https://doi.org/10.3390/min8070294 - 11 Jul 2018

Cited by 11 | Viewed by 3525

Abstract

The effects of sodium ions, phosphorus, and silicon on the eco-friendly process of vanadium precipitation by hydrothermal hydrogen reduction were investigated to establish the suitable concentrated solution system for this eco-friendly process. The results showed that sodium ions had no negative effects on [...] Read more.

The effects of sodium ions, phosphorus, and silicon on the eco-friendly process of vanadium precipitation by hydrothermal hydrogen reduction were investigated to establish the suitable concentrated solution system for this eco-friendly process. The results showed that sodium ions had no negative effects on the vanadium precipitation process. Phosphorus can reduce vanadate ion activity, and results in the decrease of vanadium precipitation percentage from 99.5% to 61.3%, as the phosphorus concentration in the feed solution increased from 0.05 g/L to 3 g/L. As a result, the aimed products of V₂O₃ were hard to be obtained, and the purity of the precipitates was lowered. Silicon can absorb in the form of H₃Si₃O₇ on the surface of the precipitates, thus it was difficult for H (activity hydrogen atom) to react with the intermediate vanadium-bearing precipitates. As a result, the vanadium precipitation percentage decreased from 99.5% to 86.2% as the silicon concentration in the feed solution increased from 0.1 g/L to 3 g/L. The aimed products of V₂O₃ were not easy to be obtained, and only the intermediate vanadium-bearing precipitates containing sodium ions were obtained. The upper limits of the concentrations of phosphorus and silicon in the feed V (V) solution were ascertained as 0.5 g/L and 0.1 g/L, respectively. As the concentrations of phosphorus and silicon in the purified alkaline-concentrated V (V) solution extracted from vanadium-bearing shale are usually below the upper limits of the concentrations, the eco-friendly process of vanadium precipitation by hydrothermal hydrogen reduction has a great application prospect in the field of vanadium extraction from vanadium-bearing shale. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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13 pages, 21872 KiB

Open AccessArticle

Effect of TiO₂ on the Sintering Behavior of Chromium-Bearing Vanadium–Titanium Magnetite

by Weidong Tang, Songtao Yang, Gongjin Cheng, Zixian Gao, He Yang and Xiangxin Xue

Minerals 2018, 8(7), 263; https://doi.org/10.3390/min8070263 - 23 Jun 2018

Cited by 11 | Viewed by 3395

Abstract

The sintering pot test was used to investigate the effect of TiO₂ on the sintering behavior of chromium-bearing vanadium–titanium magnetite (CVTM) sinter. The main characterization methods of X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy-energy disperse spectroscopy (SEM-EDS), and metallographic microscopy [...] Read more.

The sintering pot test was used to investigate the effect of TiO₂ on the sintering behavior of chromium-bearing vanadium–titanium magnetite (CVTM) sinter. The main characterization methods of X-ray fluorescence (XRF), X-ray diffraction (XRD), scanning electron microscopy-energy disperse spectroscopy (SEM-EDS), and metallographic microscopy were employed. In this study, yield, tumbler index (TI), vertical sintering speed, productivity, reduction degradation index (RDI), and reduction index (RI) were tested and calculated. The yield first increases from 82.87% to 84.37% and then decreases to 83.65%, vertical sintering speed first increases from 17.00 mm·min⁻¹ to 23.45 mm·min⁻¹ and then decreases to 20.61 mm·min⁻¹, and productivity first increases from 2.33 t·m⁻²·h⁻¹ to 3.14 t·m⁻²·h⁻¹ and then decreases to 2.69 t·m⁻²·h⁻¹ with increasing TiO₂ content. The TI increases from 45.81% to 52.09%, and RDI increases from 74.99% to 96.74%, while RI decreases from 67.92% to 47.15% with increasing TiO₂ content. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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12 pages, 2525 KiB

Open AccessArticle

Synthesis of Di-(2-ethylhexyl) Phosphoric Acid (D2EHPA)-Tributyl Phosphate (TBP) Impregnated Resin and Application in Adsorption of Vanadium(IV)

by Ruwei Zheng, Shenxu Bao, Yimin Zhang and Bo Chen

Minerals 2018, 8(5), 206; https://doi.org/10.3390/min8050206 - 10 May 2018

Cited by 38 | Viewed by 7817

Abstract

In order to improve the adsorption capability of solvent-impregnated resins (SIRs) for vanadium(IV) (V(IV)), the dual extractant (D2EHPA (Di-(2-ethylhexyl) phosphoric acid) and TBP (Tributyl phosphate)) impregnated resins (D-TIRs) were prepared by impregnating Amberlite^TM XAD-16HP macroporous resins with the mixed extractant that is [...] Read more.

In order to improve the adsorption capability of solvent-impregnated resins (SIRs) for vanadium(IV) (V(IV)), the dual extractant (D2EHPA (Di-(2-ethylhexyl) phosphoric acid) and TBP (Tributyl phosphate)) impregnated resins (D-TIRs) were prepared by impregnating Amberlite^TM XAD-16HP macroporous resins with the mixed extractant that is composed by different molar ratios of D2EHPA to TBP. The effects of the ratio of D2EHPA to TBP on the performance of D-TIRs were investigated. The results show that the impregnation ratio of the D-TIRs decreases gradually with the increasing proportion of TBP in the mixed extractant. The sole-TBP impregnated resins (TIRs) have no adsorption capability for V(IV), indicating that the adsorption of V(IV) is attributed to D2EHPA. The adsorption capacity of D-TIRs for V(IV) attained the maximum when the ratio of D2EHPA to TBP is 7:3 at pH 1.8, and it can be improved by increasing the extractants concentration during the impregnation process. Adsorption isotherm indicates that the addition of TBP can increase the adsorption capacity of D-TIRs for V(IV) from 24.65 to 29.75 mg/g after 16 h reaction. Adsorption kinetics verifies that the addition of TBP can largely accelerate the adsorption equilibrium of V(IV) onto the D-TIRs and V(IV). Electrospray ionization (ESI) mass spectra and Fourier transform infrared spectra (FT-IR) analysis indicates that the addition of TBP to D2EHPA can make some dimeric D2EHPA change to monomers by breaking the hydrogen bonds of D2EHPA-dimers, leading to the result that the pseudo-second order kinetic for the adsorption of V(IV) onto the D2EHPA impregnated resins (DIRs) converts to the pseudo-first order kinetic for that onto the D-TIRs. Also, D-TIRs have better separation capability of V(IV) from Fe(II) and Al(III) in the vanadium leaching solution than DIRs. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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11 pages, 6870 KiB

Open AccessArticle

Evaluation of Microwave Intensified Vanadium Bearing-High Carbonaceous Shale Acid Extraction Process

by Jingpeng Wang, Yimin Zhang, Tao Liu and Jing Huang

Minerals 2018, 8(3), 113; https://doi.org/10.3390/min8030113 - 9 Mar 2018

Cited by 6 | Viewed by 3870

Abstract

The microwave assisted leaching of the vanadium bearing-high carbonaceous shale process was investigated using surface response methodology (RSM) based on Box–Behnken design (BBD). The effect of important factors such as CaF₂ usage, H₂SO₄ concentration, leaching time and microwave power, [...] Read more.

The microwave assisted leaching of the vanadium bearing-high carbonaceous shale process was investigated using surface response methodology (RSM) based on Box–Behnken design (BBD). The effect of important factors such as CaF₂ usage, H₂SO₄ concentration, leaching time and microwave power, as well as the interactive coefficients, the signification of the model and factors were analyzed. With the condition of 9.8 wt % CaF₂, 23.0 vol % H₂SO₄, 170.6 min and 350 W, the actual values of vanadium (V) leaching efficiency in microwave heating (MH) and conventional heating (CH) were 85.43% and 79.64%, which agreed well with the predicted values. Meanwhile, the influence order of the factors in MH and CH was CaF₂ dosage > H₂SO₄ concentration > leaching time. Microwave was an efficacious impetus for V extraction, but the microwave power itself was not a significant factor when the temperature of leaching system was high enough. The further characterization of mineral components before and after leaching confirmed that the prior dissolving of muscovite and pyrite in MH was intensified, while both minerals were in fine grains and filled with black carbon. The selective heating of carbon and pyrite sequenced the large temperature gradient between solids and liquids, which accelerated the dissolving reaction of muscovite with CaF₂ present in MH condition. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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16 pages, 5545 KiB

Open AccessArticle

Large-Scale Consumption and Zero-Waste Recycling Method of Red Mud in Steel Making Process

by Guoshan Ning, Bo Zhang, Chengjun Liu, Shuai Li, Yun Ye and Maofa Jiang

Minerals 2018, 8(3), 102; https://doi.org/10.3390/min8030102 - 6 Mar 2018

Cited by 32 | Viewed by 5946

Abstract

To release the environmental pressure from the massive discharge of bauxite residue (red mud), a novel recycling method of red mud in steel making process was investigated through high-temperature experiments and thermodynamic analysis. The results showed that after the reduction roasting of the [...] Read more.

To release the environmental pressure from the massive discharge of bauxite residue (red mud), a novel recycling method of red mud in steel making process was investigated through high-temperature experiments and thermodynamic analysis. The results showed that after the reduction roasting of the carbon-bearing red mud pellets at 1100–1200 °C for 12–20 min, the metallic pellets were obtained with the metallization ratio of ≥88%. Then, the separation of slag and iron achieved from the metallic pellets at 1550 °C, after composition adjustment targeting the primary crystal region of the 12CaO·7Al₂O₃ phase. After iron removal and composition adjustment, the smelting-separation slag had good smelting performance and desulfurization capability, which meets the demand of sulfurization flux in steel making process. The pig iron quality meets the requirements of the high-quality raw material for steel making. In virtue of the huge scale and output of steel industry, the large-scale consumption and zero-waste recycling method of red mud was proposed, which comprised of the carbon-bearing red mud pellets roasting in the rotary hearth furnace and smelting separation in the electric arc furnace after composition adjustment. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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18 pages, 21380 KiB

Open AccessArticle

Calcium Chloride-Assisted Segregation Reduction of Chromite: Influence of Reductant Type and the Mechanism

by Dawei Yu and Dogan Paktunc

Minerals 2018, 8(2), 45; https://doi.org/10.3390/min8020045 - 29 Jan 2018

Cited by 10 | Viewed by 6316

Abstract

This paper describes an innovative process for the production of ferrochromium alloy via segregation reduction of chromite at 1300 °C in the presence of calcium chloride. Both charcoal and petroleum coke were used as the reductant. Individual polycrystalline ferrochrome carbide particles were produced, [...] Read more.

This paper describes an innovative process for the production of ferrochromium alloy via segregation reduction of chromite at 1300 °C in the presence of calcium chloride. Both charcoal and petroleum coke were used as the reductant. Individual polycrystalline ferrochrome carbide particles were produced, with their particle size and shape resembling that of the starting carbon particles. Interactions among calcium chloride, clinochlore, and chromite resulted in the formation of Ca-bearing chromite, wadalite, and gaseous chlorides. Monocrystalline ferrochrome carbide whiskers were formed only when charcoal in the presence of calcium chloride was used to reduce the chromite fraction containing large amounts of siliceous gangue. Incorporating thermodynamic evaluations, a possible segregation reduction mechanism is suggested based on the characterization of the products using scanning electron microscopy, energy dispersive spectroscopy, X-ray powder diffraction, and electron probe microanalysis, combined with thermogravimetric analysis. Metallization within chromite particles was minimized, which is suggested to be due to the ubiquitous presence of molten and gaseous calcium chloride between the chromite and carbon particles, and especially in the porous rim of the chromite particles during reduction, resulting in restricted metallization only on the carbon particles. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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Review

Jump to: Research

17 pages, 6835 KiB

Open AccessReview

Spodumene: The Lithium Market, Resources and Processes

by Colin Dessemond, Francis Lajoie-Leroux, Gervais Soucy, Nicolas Laroche and Jean-François Magnan

Minerals 2019, 9(6), 334; https://doi.org/10.3390/min9060334 - 29 May 2019

Cited by 143 | Viewed by 32793

Abstract

This literature review gives an overview of the lithium industry, including the lithium market, global resources, and processes of lithium compounds production. It focuses on the production of lithium compounds from spodumene minerals. Spodumene is one of the most critical minerals nowadays, due [...] Read more.

This literature review gives an overview of the lithium industry, including the lithium market, global resources, and processes of lithium compounds production. It focuses on the production of lithium compounds from spodumene minerals. Spodumene is one of the most critical minerals nowadays, due to its high lithium content and high rate of extraction. Lithium is one of the most sought-after metals, due to the ever-growing demand for lithium-ion batteries (LiBs). The data on lithium extraction from minerals is scattered through years of patents, journal articles, and proceedings; hence, requiring an in-depth review, including the comprehension of the spodumene phase system, the phase conversion processes, and the lithium extraction processes. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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Open AccessReview

New Trends in the Application of Carbon-Bearing Materials in Blast Furnace Iron-Making

by Hesham Ahmed

Minerals 2018, 8(12), 561; https://doi.org/10.3390/min8120561 - 1 Dec 2018

Cited by 41 | Viewed by 9217

Abstract

The iron and steel industry is still dependent on fossil coking coal. About 70% of the total steel production relies directly on fossil coal and coke inputs. Therefore, steel production contributes by ~7% of the global CO₂ emission. The reduction of CO [...] Read more.

The iron and steel industry is still dependent on fossil coking coal. About 70% of the total steel production relies directly on fossil coal and coke inputs. Therefore, steel production contributes by ~7% of the global CO₂ emission. The reduction of CO₂ emission has been given highest priority by the iron- and steel-making sector due to the commitment of governments to mitigate CO₂ emission according to Kyoto protocol. Utilization of auxiliary carbonaceous materials in the blast furnace and other iron-making technologies is one of the most efficient options to reduce the coke consumption and, consequently, the CO₂ emission. The present review gives an insight of the trends in the applications of auxiliary carbon-bearing material in iron-making processes. Partial substitution of top charged coke by nut coke, lump charcoal, or carbon composite agglomerates were found to not only decrease the dependency on virgin fossil carbon, but also improve the blast furnace performance and increase the productivity. Partial or complete substitution of pulverized coal by waste plastics or renewable carbon-bearing materials like waste plastics or biomass help in mitigating the CO₂ emission due to its high H₂ content compared to fossil carbon. Injecting such reactive materials results in improved combustion and reduced coke consumption. Moreover, utilization of integrated steel plant fines and gases becomes necessary to achieve profitability to steel mill operation from both economic and environmental aspects. Recycling of such results in recovering the valuable components and thereby decrease the energy consumption and the need of landfills at the steel plants as well as reduce the consumption of virgin materials and reduce CO₂ emission. On the other hand, developed technologies for iron-making rather than blast furnace opens a window and provide a good opportunity to utilize auxiliary carbon-bearing materials that are difficult to utilize in conventional blast furnace iron-making. Full article

(This article belongs to the Special Issue Towards Sustainability in Extractive Metallurgy)

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