Research

11 pages, 3911 KiB

Open AccessArticle

Desorption and Reuse of Pb-BHA-NaOL Collector in Scheelite Flotation

by Jianjun Wang, Zhiyong Gao and Wei Sun

Minerals 2023, 13(4), 538; https://doi.org/10.3390/min13040538 - 12 Apr 2023

Cited by 2 | Viewed by 952

Pb and BHA in Pb-BHA-NaOL collector assembled by lead nitrate (Pb), benzohydroxamic acid (BHA), and sodium oleate (NaOL) with a 240:120:1 molar ratio in scheelite flotation have the common defects of flotation reagents including high cost, environmental pollution and reducing hydrometallurgy efficiency. Therefore, [...] Read more.

Pb and BHA in Pb-BHA-NaOL collector assembled by lead nitrate (Pb), benzohydroxamic acid (BHA), and sodium oleate (NaOL) with a 240:120:1 molar ratio in scheelite flotation have the common defects of flotation reagents including high cost, environmental pollution and reducing hydrometallurgy efficiency. Therefore, in this study, the efficient desorption and reuse of Pb and BHA adsorbed on the scheelite surfaces was first proposed. The desorption test results showed that 80.71% Pb and 70.93% BHA could be efficiently desorbed from the scheelite concentrate surfaces through strong stirring for 15 min at pH 13.0 and a speed of 1600 r/min. The reuse of the desorbed collector could save 67% Pb and 75% BHA. The results of desorption and reuse tests of the real ore also exhibited high feasibility in industrial application. Fourier transform infrared spectroscopy analysis revealed that Pb-O, C=O, and C-N groups of Pb and BHA adsorbed on the scheelite surfaces obviously weakened or disappeared. Atomic force microscopy analysis further confirmed that most of the Pb and BHA on the scheelite surfaces were removed. Therefore, this work not only solves the above defects of the collector but also provides a reference for the desorption and reuse of other flotation reagents. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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19 pages, 7612 KiB

Open AccessArticle

Extraction of Iron and Alumina from Red Mud with a Non-Harmful Magnetization Sintering Process

by Rui Chen, Lin Shi, Haoyong Huang and Jie Yuan

Minerals 2023, 13(3), 452; https://doi.org/10.3390/min13030452 - 22 Mar 2023

Cited by 3 | Viewed by 2339

Abstract

Red mud, which could cause numerous problems to the environment, is a hazardous waste generated from the alumina smelting industry. In general, the storage and harmless utilization of red mud are hard to implement due to its fine particle size and high alkalinity. [...] Read more.

Red mud, which could cause numerous problems to the environment, is a hazardous waste generated from the alumina smelting industry. In general, the storage and harmless utilization of red mud are hard to implement due to its fine particle size and high alkalinity. This study put forward a novel process to separate iron (MgFe₂O₄) and alumina (Al₂O₃) in red mud by a magnetization sintering method. The magnesium oxide was added to transform the nonmagnetic Fe₂O₃ into magnetic MgFe₂O₄ to achieve physical separation of iron-bearing minerals, and the alumina-bearing minerals were converted into dissoluble NaAlO₂ minerals in a one-step reaction. The atmospheric pressure leaching process was adopted in this study for alumina resource recovery. To achieve clean alumina production, the silicate in the leaching solution was removed by adding the slightly soluble CaSO₄, and the entire process becomes clean and harmless. The feasibility of the process was verified by thermodynamic analysis, and a series of experiments were performed to detect the optimum MgO/(Fe₂O₃ + MgO) ratio and the calcining and leaching conditions. The morphological and mineralogical characteristics of modified red mud, leaching red mud, and magnetic separation product were studied by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) energy dispersive spectroscopy (EDS). It was observed that under the optimal conditions with MgO/(Fe₂O₃ + MgO) of 14.89% to recover iron and aluminum, the corresponding recovery rates were 67.54% and 73.01% respectively, and the iron grade was 30.46%. The EDS results showed that the obtained Mg/Fe ratio of the magnetic separation product was 0.4677–0.528, which is slightly different from that of the standard MgFe₂O₄ at 0.5. This new method can promote the development of comprehensive utilization of red mud and iron production. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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12 pages, 5121 KiB

Open AccessArticle

The Surface Structure Change of Columbite-(Fe) Dissolution in H₂SO₄

by Xiao Guo, Dan Wang and Qiuju Li

Minerals 2023, 13(3), 445; https://doi.org/10.3390/min13030445 - 21 Mar 2023

Cited by 1 | Viewed by 1117

Abstract

The mineral surface structure and ions’ interaction were of significant interest to understanding mineral dissolution and reaction. In this study, X-ray photoemission spectroscopy combined with ICP emission spectrometer was used to investigate the influence of the leaching reaction conditions of 8 M dilute [...] Read more.

The mineral surface structure and ions’ interaction were of significant interest to understanding mineral dissolution and reaction. In this study, X-ray photoemission spectroscopy combined with ICP emission spectrometer was used to investigate the influence of the leaching reaction conditions of 8 M dilute sulfuric acid and 12 M concentrated sulfuric acid on the surface chemical composition, chemical (valence) state and ion distribution of Columbite-(Fe) (FeNb₂O₆). The binding energy of the cations (Fe, Nb) bonding with different anions (O²⁻, SO₄²⁻) and the ratio of Fe³⁺/Fe²⁺ oxidation–reduction provided direct understanding of Fe and Nb releasing from the mineral surface during leaching. The results showed that the binding energy of the Nb⁵⁺-O bond was much smaller than that of Nb⁵⁺-SO₄, and the binding energy decreased in sequence as Nb⁵⁺-O < Fe²⁺-O < Fe³⁺-O and increased in sequence as Fe³⁺-SO₄ < Fe²⁺-SO₄ < Nb⁵⁺-SO₄. The mineral surface reaction during the leaching could be expressed with the formula: Fe-O + H₂SO₄ → Fe-SO₄ + H₂O, Nb-O + H₂SO₄ → Nb-SO₄ + H₂O. The results also revealed that Nb dissolution from Columbite-(Fe) occurred more easily compared to Fe. Nb dissolution from the mineral was owed to the content of H⁺ in solution, and increasing the H⁺ concentration could promote the dissolution. For Fe dissolution from the mineral, the oxidation potential could play an effective role in enhancement dissolution. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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13 pages, 11110 KiB

Open AccessArticle

Bioleaching of Gold in Mine Tailings by Alcaligenes faecalis

by Yilman S. Pineda, Stephanie L. Devries, Nicholas C. Steiner and Karin A. Block-Cora

Minerals 2023, 13(3), 410; https://doi.org/10.3390/min13030410 - 15 Mar 2023

Cited by 1 | Viewed by 2172

Abstract

We conducted a series of column experiments on tailing heap samples from the Picacho mine in California to determine the ability of the native Gram-negative bacteria, Alcaligenes faecalis, to leach gold. To mimic heap leaching using our technique, unprocessed and unsorted tailings [...] Read more.

We conducted a series of column experiments on tailing heap samples from the Picacho mine in California to determine the ability of the native Gram-negative bacteria, Alcaligenes faecalis, to leach gold. To mimic heap leaching using our technique, unprocessed and unsorted tailings of mixed grain sizes were placed into columns and leached for three weeks with four treatments: (1) deionized water, (2) bacteria, (3) NaCN by bacteria and (4) NaCN. In all of the experimental runs, the total Au (mg) recovered from the columns treated with A. faecalis and NaCN followed by A. faecalis yielded gold amounts that were higher than those from the deionized water control, and lower than the columns treated with cyanide. However, the total yields were variable across runs, which we attribute to the inherent heterogeneity of gold distribution in the samples. Statistical tests show that the yields from the treatments employing bacteria and/or cyanide were different from those that employed deionized water alone. Our results support previous studies that showed that exudates of A faecalis promoted reduction of Au³⁺, catalyzing extracellular Au⁰ particles under alkaline conditions. We propose that A. faecalis is a possible novel alternative to cyanide treatment for recovering Au from mine tailings, and recommend optimization of the method. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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14 pages, 3295 KiB

Open AccessFeature PaperArticle

KOH-Based Hydrothermal Synthesis of Iron-Rich Titanate Nanosheets Assembled into 3D Hierarchical Architectures from Natural Ilmenite Mineral Sands

by Karina J. Lagos, Bojan A. Marinkovic, Anja Dosen, Alexis Debut, Karla Vizuete, Victor H. Guerrero, Emilio Pardo and Patricia I. Pontón

Minerals 2023, 13(3), 406; https://doi.org/10.3390/min13030406 - 15 Mar 2023

Viewed by 1347

Abstract

The synthesis of titanate nanostructures from low-cost mineral precursors is a topic of continuous interest, considering not only their fundamental aspects but also the benefits of incorporating such nanomaterials in a wide variety of applications. In this work, iron-rich titanate nanosheets were synthesized [...] Read more.

The synthesis of titanate nanostructures from low-cost mineral precursors is a topic of continuous interest, considering not only their fundamental aspects but also the benefits of incorporating such nanomaterials in a wide variety of applications. In this work, iron-rich titanate nanosheets were synthesized from Ecuadorian ilmenite sands (ilmenite–hematite solid solution-IHSS) through an alkaline hydrothermal treatment (AHT) using potassium hydroxide (KOH). The effect of the duration of the KOH-AHT was assessed at 180 °C for 24, 48, 72, and 96 h. The morphology evolution over time and the plausible formation mechanisms of titanate nanostructures were discussed. The most significant morphological transformation was observed after 72 h. At this time interval, the titanate nanostructures were assembled into well-defined 3D hierarchical architectures such as book-block-like arrangements with open channels. Based on X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) analyses, it was determined that these nanostructures correspond to iron-rich layered titanates (Fe/Ti mass ratio of 7.1). Moreover, it was evidenced that the conversion of the precursor into layered nanostructures was not complete, since for all the tested reaction times the presence of remaining IHSS was identified. Our experiments demonstrated that the Ecuadorian ilmenite sands are relatively stable in KOH medium. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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9 pages, 2565 KiB

Open AccessArticle

The Effect of Microwave Pre-treatment on the Magnetic Properties of Enargite and Tennantite and Their Separation from Chalcopyrite

by Ahmed M. Elmahdy, Hajime Miki, Keiko Sasaki and Mohsen Farahat

Minerals 2023, 13(3), 334; https://doi.org/10.3390/min13030334 - 27 Feb 2023

Cited by 2 | Viewed by 1043

Abstract

The effect of microwave pre-treatment on the magnetic properties of tennantite and enargite was investigated. Magnetic susceptibility, XRD, and XPS characterization of tennantite and enargite before and after treatment were conducted to explore the changes in their magnetic properties. Moreover, magnetic separation of [...] Read more.

The effect of microwave pre-treatment on the magnetic properties of tennantite and enargite was investigated. Magnetic susceptibility, XRD, and XPS characterization of tennantite and enargite before and after treatment were conducted to explore the changes in their magnetic properties. Moreover, magnetic separation of chalcopyrite binary mixtures with enargite and tennantite was performed. The results showed insignificant effects on the magnetic susceptibility of the two minerals after microwave pre-treatment. Magnetic separation results showed arsenic rejection by 84.2%, and 76.3% in the case of enargite and tennantite binary mixtures with chalcopyrite; respectively. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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19 pages, 7592 KiB

Open AccessArticle

Modelling Flocculation in a Thickener Feedwell Using a Coupled Computational Fluid Dynamics–Population Balance Model

by Hailong Tang, Yuping Fan, Xiaomin Ma, Xianshu Dong, Ming Chang and Na Li

Minerals 2023, 13(3), 309; https://doi.org/10.3390/min13030309 - 22 Feb 2023

Cited by 3 | Viewed by 1783

Abstract

The flocculation that takes place in the central feedwell of the thickener plays a crucial role in the coal-slurry thickening process, which is not only complex but also largely influenced by the flow characteristics. A coupled computational fluid dynamics–population balance model (CFD–PBM) was [...] Read more.

The flocculation that takes place in the central feedwell of the thickener plays a crucial role in the coal-slurry thickening process, which is not only complex but also largely influenced by the flow characteristics. A coupled computational fluid dynamics–population balance model (CFD–PBM) was used to model the complex flocculation-thickening behaviour in an industrial-scale gravity thickener. The initialisation parameters of the inlet flow were obtained through self-designed image-recognition experiments, and then the effects of different types of conical deflectors on the floc distribution were simulated and analysed using them. The results showed that, under the condition that the angle of the conical deflector’s sides in the vertical plane was known, a reasonable increase in the height of the bottom surface could reduce the annular spanwise vortices at the underflow of the feedwell, thereby avoiding the erosion of the inlet flow and the annular spanwise vortex on the floc deposition layer. However, excessive height on the part of the conical deflector could affect the flocculation effect of solid particles. For the same central feedwell size of the thickener as in the simulation, the best flocculation effect was achieved at an angle of α = 24° in the vertical plane of the conical deflector. Turbulence regulation of the conical deflector promotes the aggregation of fine particles in the fluid of the feedwell, providing a new method for the intensification of the flocculation-concentration process. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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14 pages, 10456 KiB

Open AccessFeature PaperArticle

Effect of Gangue Minerals on Pulp Rheology and Flotation Behavior of Smithsonite

by Yanbo Shang and Chuanyao Sun

Minerals 2023, 13(1), 66; https://doi.org/10.3390/min13010066 - 30 Dec 2022

Cited by 2 | Viewed by 1356

Abstract

The pulp rheology is an important factor affecting flotation performance. Gangue minerals have a significant impact on the rheological property of smithsonite (ZnCO₃). The complex pulp rheology (high viscosity, poor dispersion) will adversely affect the grade and recovery of concentrate. To [...] Read more.

The pulp rheology is an important factor affecting flotation performance. Gangue minerals have a significant impact on the rheological property of smithsonite (ZnCO₃). The complex pulp rheology (high viscosity, poor dispersion) will adversely affect the grade and recovery of concentrate. To address this problem, the effect of gangue minerals (kaolinite, calcite, and quartz) on the rheological property and flotation behavior of smithsonite was investigated with the pulp rheology measurement and a flotation test. The results showed that the flotation recovery is closely associated with the pulp rheology and high apparent viscosity and that yield stress resulted in a low recovery. The detrimental influence of gangue minerals on the rheology and yield of smithsonite was kaolinite > calcite > quartz. The coarse mineral particles (150–74 μm, 74–38 μm) could reduce the apparent viscosity and yield stress and present good floatability, while fine particles (38–23 μm, −23 μm) could greatly increase the values and show poor floatability. Therefore, to control the pulp rheology of smithsonite, it is necessary to remove fine gangue minerals (−38 μm) before flotation, especially the fine kaolinite. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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14 pages, 5391 KiB

Open AccessArticle

Simulation and Validation of Discrete Element Parameter Calibration for Fine-Grained Iron Tailings

by Jinxia Zhang, Zhenjia Chang, Fusheng Niu, Yuying Chen, Jiahui Wu and Hongmei Zhang

Minerals 2023, 13(1), 58; https://doi.org/10.3390/min13010058 - 29 Dec 2022

Cited by 2 | Viewed by 1913

Abstract

In order to improve the calculation efficiency of a discrete element EDEM (Discrete Element Method) numerical simulation software for micron particles, the particle model is linearly enlarged. At the same time, the parameters of the amplified particles were calibrated according to the Hertz-Mindlin [...] Read more.

In order to improve the calculation efficiency of a discrete element EDEM (Discrete Element Method) numerical simulation software for micron particles, the particle model is linearly enlarged. At the same time, the parameters of the amplified particles were calibrated according to the Hertz-Mindlin with JKR (Johnson-Kendall-Roberts) contact model to make the amplified particles have the same particle flow characteristics as the actual particles. Actual tests were utilized to gather the angle of repose of the microfine iron tailings, which was then used as a reference value for response surface studies based on the JKR contact model from six factors connected to the fine iron tailings particles. The Plackett-Burman test was used to identify three parameters that had a significant effect on the rest angle: static friction factor; rolling friction factor; and JKR surface energy. The Box-Behnken experiment was used to establish a second-order regression model of the rest angle, and the significant parameters and the optimized parameters were: surface energy JKR coefficient 0.459; particle-particle static friction coefficient 0.393; and particle-particle dynamic friction coefficient 0.393, with a dynamic friction coefficient between particles of 0.106. By entering the parameters into the discrete element program, the angle of repose generated from the simulations was compared with the real test values, and the error was 1.56%. The contact parameters obtained can be used in the discrete element simulation of the amplified particles of fine-grained iron tailings, providing an EDEM model reference for the numerical simulation of fine-grained iron tailings particles. There is no discernible difference between the actual and simulated angles. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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17 pages, 4811 KiB

Open AccessArticle

The Effect of Clay Minerals on Fayalite Slag Structure and Refractory Brick Wear during Copper Smelting

by Julio Ossandón, Leandro Voisin and Camila Pizarro

Minerals 2022, 12(11), 1431; https://doi.org/10.3390/min12111431 - 10 Nov 2022

Viewed by 1351

Abstract

Metallic copper production via the pyrometallurgical route is hindered due to the increased presence of gangue in the clay minerals in copper sulfide concentrates and its unpredictable effect on this operation. In this study, the relationship between smelting copper slag composition, including the [...] Read more.

Metallic copper production via the pyrometallurgical route is hindered due to the increased presence of gangue in the clay minerals in copper sulfide concentrates and its unpredictable effect on this operation. In this study, the relationship between smelting copper slag composition, including the clay components and the refractory brick wear, was investigated in experimental laboratory tests. Synthetic fayalite slags doped with 2, 5, or 8 wt% high-purity kaolinite or montmorillonite were introduced into magnesia chromite refractory crucibles and melted in an electrical furnace under the controlled partial pressure of oxygen (10⁻⁸ atm) for 12 h at temperatures of 1250 and 1300 °C. After the experimental time, the crucibles were quenched in water, and the obtained samples were analyzed using the XRD, SEM, and ICP techniques. According to the results, at 1300 °C the presence of montmorillonite in the fayalite-based slag promoted infiltration through the refractory brick and increased the dissolution of the magnesia component from the hot face. In the case of the kaolinite, the infiltration was even higher, but the magnesia dissolution was delayed. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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31 pages, 5418 KiB

Open AccessFeature PaperArticle

Evaluation of the Relationship between the Milling Breakage Parameters and Mineralogical Data: A Case Study of Three Copper Ores from a Multi-Mineralised Deposit

by Titus Nghipulile, Thomas Ehongo Moongo, Godfrey Dzinomwa, Sandile Nkwanyana, Benjamin Mapani and Jaquiline Tatenda Kurasha

Minerals 2022, 12(10), 1263; https://doi.org/10.3390/min12101263 - 06 Oct 2022

Cited by 2 | Viewed by 1912

Abstract

The study evaluated the milling kinetics of three copper ores, from a multi-mineralised deposit, which were identified as sulphide 1 (with bornite as a dominant copper mineral), sulphide 2 (mainly composed of chalcopyrite) and oxide (with malachite as a dominant copper mineral) and [...] Read more.

The study evaluated the milling kinetics of three copper ores, from a multi-mineralised deposit, which were identified as sulphide 1 (with bornite as a dominant copper mineral), sulphide 2 (mainly composed of chalcopyrite) and oxide (with malachite as a dominant copper mineral) and related the breakage parameters to the mineral composition data. Five mono-size fractions between 1000 µm and 212 µm were dry milled for short grinding times in the laboratory ball mill in order to obtain data for predicting breakage rate parameters. The analytical and mineralogical characterisation of the ores were performed using X-ray fluorescence (XRF) analysis, scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) analysis, optical microscopy analysis and X-ray diffractometer (XRD). The mineralogy data showed that quartz was the abundant gangue mineral (average for each ore was above 60% (w/w)), followed by K-feldspar minerals (orthoclase and microcline) which constituted between 4% (w/w) and 6% (w/w) and the remainder are the minor calcite and dolomite minerals which are also in the host rock. The experimental milling kinetics parameters and mineralogical data were used to assess the robustness of the heterogeneous (two-component) and homogeneous (single-component) first-order rate breakage models. The mineral composition data were used for setting up the predictions of breakage parameters in the two-component and single-component first-order breakage models. The experimental data fitted better on the two-component breakage model than the single-component breakage model. These results highlighted the influence of two groups of minerals (generally classed as valuable and gangue minerals). The breakage data showed that the selection function for the hard component (the gangue minerals) has a dominant contribution to the overall selection function of the ores, with S_iA correlating fairly well with experimental S_i. The parameter a in the Austin empirical breakage model was relatively similar (approximately 1) for all three ores, which confirms similar milling conditions to which the ores were subjected to. The data suggests that there is a relationship between breakage parameter α (material-specific parameter) in the Austin empirical breakage model and brittleness index β_i (calculated from the mineralogical composition of the gangue phase). No clear trends could be deduced from the cumulative breakage distributions of the three ores. This highlights the complexity of developing relationships between the mineralogical composition data and breakage distributions of the ores which are extracted from the same deposit and with comparable gangue composition. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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13 pages, 3852 KiB

Open AccessArticle

Efficient Recovery of the Combined Copper Resources from Copper Oxide Bearing Limonite Ore by Magnetic Separation and Leaching Technology

by Zaihua Peng, Xinzhuang Fu, Zujiang Pan, Ya Gao, Dongdong He, Xiaohui Fan, Tong Yue and Wei Sun

Minerals 2022, 12(10), 1258; https://doi.org/10.3390/min12101258 - 04 Oct 2022

Cited by 2 | Viewed by 1657

Abstract

The reserve of the copper-oxide-bearing limonite ore (COBL ore) in Yulong Copper Co., Ltd. is up to 20 million tons with 1.79% of copper content. The characters of the copper resources in the COBL ore are high-proportioned oxidation state (99.98%) and combined state [...] Read more.

The reserve of the copper-oxide-bearing limonite ore (COBL ore) in Yulong Copper Co., Ltd. is up to 20 million tons with 1.79% of copper content. The characters of the copper resources in the COBL ore are high-proportioned oxidation state (99.98%) and combined state (84.83%). The combined copper oxide is mainly copper-oxide-bearing limonite, which has a copper content of more than 78%. Because of the high altitude and average annual temperature of 15 °C in Tibet, fire leaching cannot be adopted. The leaching efficiency of copper from COBL ore using direct leaching of sulfuric acid is only 40%, which is greatly influenced by temperature and time. Based on the characteristics of COBL ore, a novel combined method of magnetic separation and individual leaching has been proposed to efficient recover copper resources. Experimental results show that the magnetic concentrates and tailings were obtained by magnetic separation of COBL ore at 0.6 T with the yields were 59.65% and 40.35%, respectively. Due to the obvious leaching properties difference of the magnetic concentrates and tailings, individual leaching process routes were used to treat them. The magnetic concentrate was leached with stirring for 3 days at room temperature (20 °C), and the magnetic tailing was easily leached for 4 h at 40 °C. The recovery efficiency of total copper was 72%, which was about 32% higher than that of the single leaching of the COBL ore. The method proposed in this study achieves environmentally friendly, low energy consumption, and efficient extraction of refractory copper oxide ore. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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15 pages, 4248 KiB

Open AccessArticle

Flotation Separation of Covellite and Enargite via Oxidation Treatment

by Yonggang Gan, Rongdong Deng and Quanjun Liu

Minerals 2022, 12(8), 970; https://doi.org/10.3390/min12080970 - 29 Jul 2022

Cited by 2 | Viewed by 1449

Abstract

The flotation separation of enargite from copper sulfide minerals is difficult owing to the similar floatability and reagent adsorption characteristics of these minerals. In this study, the effect of oxidation treatment using NaClO flow with FeCl₃ on the flotation separation of covellite [...] Read more.

The flotation separation of enargite from copper sulfide minerals is difficult owing to the similar floatability and reagent adsorption characteristics of these minerals. In this study, the effect of oxidation treatment using NaClO flow with FeCl₃ on the flotation separation of covellite and enargite was systematically investigated. Micro-flotation tests and contact angle measurements indicated that the addition of NaClO and FeCl₃ increased the hydrophobicity difference between covellite and enargite. The bench-scale flotation test results show that the bulk copper concentrate could be separated into two products: a low-arsenic-containing (0.46%) and a high-arsenic-containing (5.18%) copper concentrate. X-ray photoelectron spectroscopy and scanning electron microscopy revealed that the oxidization treatment of NaClO caused the accumulation of oxides on the covellite surface, but not on the enargite surface. The varying precipitation of ferric hydroxide on the surfaces of covellite and enargite further exacerbated the difference in the hydrophilicity of these minerals. Thus, a possible method for separating enargite from covellite was obtained through oxidation treatment using NaClO and FeCl₃. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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11 pages, 3693 KiB

Open AccessArticle

Dissolution Behavior of Sodium Phosphate in a Na₃PO₄–Na₂WO₄–NaOH Solution System

by Bing-Xuan He, Yong Liang, Ze-Kun Fan, Lue-Wei Xu, De-Gang Liu and Guo-Zuan Xu

Minerals 2022, 12(6), 732; https://doi.org/10.3390/min12060732 - 08 Jun 2022

Cited by 2 | Viewed by 2976

Abstract

Sodium hydroxide autoclaving is the main method for smelting scheelite in China. In this method, sodium phosphate is added as an additive to realize the highly efficient decomposition of scheelite, and a crude sodium tungstate solution containing sodium phosphate and sodium hydroxide is [...] Read more.

Sodium hydroxide autoclaving is the main method for smelting scheelite in China. In this method, sodium phosphate is added as an additive to realize the highly efficient decomposition of scheelite, and a crude sodium tungstate solution containing sodium phosphate and sodium hydroxide is obtained. In the subsequent process of ion exchange, phosphorus ions in the solution compete with the resin adsorption of tungstate, which reduces the adsorption capacity of the resin and endangers the purity of the subsequent sodium tungstate solution. To remove the phosphorus from crude sodium tungstate solution, a chemical purification method is usually adopted. The principle of the chemical purification method is to use chemical reagents to react with impurities to form precipitates to achieve the purpose of impurity removal. Because of the advantages of simple industrial implementation and high impurity removal efficiency, it has been widely used in phosphorus removal from crude sodium tungstate solution. However, in the process of phosphate removal in a crude sodium phosphate solution, the chemical purification method has some disadvantages. First, the additional cost of chemical reagents is required, and other metal impurities from chemical reagents would be introduced to crude sodium tungstate solution. Second, phosphate impurity removed by the chemical precipitation method is usually sedimented in other forms but sodium phosphate, which makes the phosphate resource unable to be recycled for tungsten smelting. Therefore, a novel phosphorus removal method needs to be developed. The dissolution behavior of sodium phosphate in a Na₃PO₄–Na₂WO₄–NaOH system was investigated in this paper. The results showed that in binary or ternary solution systems of sodium phosphate, sodium tungstate, and sodium hydroxide, the common-ion effect and salt effect exist simultaneously. The common-ion effect decreases the solubility of sodium phosphate, while the salt effect increases the solubility of sodium phosphate. Increasing the concentration of sodium hydroxide or sodium tungstate and lowering the temperature of the solution can greatly reduce the phosphorus concentration in crude sodium tungstate solution, making the crude sodium tungstate solution meet industrial requirements of ion exchange. The results of the study lay a theoretical foundation for the development of new phosphorus removal methods. Full article

(This article belongs to the Special Issue Advances in Mineral Processing and Process Engineering)

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