Valuable Metals Recovery by Mineral Processing and Hydrometallurgy

A special issue of Minerals (ISSN 2075-163X). This special issue belongs to the section "Mineral Processing and Extractive Metallurgy".

Deadline for manuscript submissions: closed (30 November 2023) | Viewed by 36403

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Guest Editor
Mineral Processing and Recycling, University of Mining and Geology, St. Ivan Rilski, 1700 Sofia, Bulgaria
Interests: processing of ores, concentrates, liquid and solid technogenic waste—hydrometallurgical, flotation, physicochemical, chemical and electrochemical methods; wastewater purification; mobilization and immobilization of water and soil pollutants

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Guest Editor
Bulgarian Academy of Sciences, 1040 Sofia, Bulgaria
Interests: new technologies in the processing of minerals (lead-zinc, copper-pyrite, copper-molybdenum ores); wastewater and washing acids purification; technogenic waste utilization; electrochemical technologies in water purification; energy state of minerals; environment protection

Special Issue Information

Dear Colleagues,

Sustainable development of our society, the breakthrough innovations, as well as we all need metals. All metals (not only precious and classified as critical for the present and near future) required both for high technologies and our everyday life are valuable and their demand will increase with time. Humankind is forced to use leaner and more complex processing for ores, which requires novel technological solutions for mineral processing and metal extraction. In order to obtain enough metals for our future, the recovery of metals from secondary sources, such as waste from mining, mineral processing and extractive metallurgy, has to be considered.

Potential challenges to future metals extraction technologies also include the accelerating climate change, the soaring energy prices, and, perhaps the most important future problem, the lack of clean water, along with the need to use resources efficiently and comprehensively, while also protecting the environment.

The solutions to all the aforementioned problems require new theoretical scientific background and technical developments, including reagents, and operational innovations of processes and technologies—when the problems associated with both primary ores and secondary technogenic resources are tackled.

Papers presenting solutions and discussing all the above-mentioned aspects and challenges to metals recovery by mineral processing and hydrometallurgy are invited for this Special Issue.

Prof. Dr. Marinela Panayotova
Prof. Dr. Vladko Panayotov
Guest Editors

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Keywords

  • mineral processing
  • comminution
  • magnetic separation
  • flotation
  • flow sheet
  • flotation kinetics
  • recovery
  • sulphide ore
  • oxide ore
  • carbonate ore
  • refractory ore
  • flotation separation mechanism
  • flotation selectivity
  • flotation reagent
  • electrochemical
  • flotation concentrate
  • process water
  • water saving in mineral processing
  • mineral processing wastewater treatment and recycling
  • industrial testing
  • flotation tailings
  • mining tailings
  • mineral recycling
  • extractive metallurgy
  • leaching
  • leaching kinetics
  • pregnant leach solution
  • solvent extraction
  • precipitation, cementation
  • electrowinning
  • water saving in hydrometallurgy
  • extractive waste recycling
  • sustainable recovery of metals
  • control, optimization and automation in mineral processing and hydrometallurgy
  • environment protection

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Published Papers (15 papers)

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Editorial

Jump to: Research, Review

5 pages, 152 KiB  
Editorial
Editorial for the Special Issue: “Valuable Metals Recovery by Mineral Processing and Hydrometallurgy”
by Marinela Panayotova and Vladko Panayotov
Minerals 2024, 14(7), 653; https://doi.org/10.3390/min14070653 - 26 Jun 2024
Cited by 1 | Viewed by 1143
Abstract
Achieving the sustainable development of our society and facilitating breakthrough innovations necessitates metals [...] Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)

Research

Jump to: Editorial, Review

18 pages, 4156 KiB  
Article
Bioleaching of Chalcopyrite by a New Strain Leptospirillum ferrodiazotrophum Ksh-L Isolated from a Dump-Bioleaching System of Kashen Copper-Molybdenum Mine
by Anna Khachatryan, Narine Vardanyan, Sabine Willscher, Garegin Sevoyan, Ruiyong Zhang and Arevik Vardanyan
Minerals 2024, 14(1), 26; https://doi.org/10.3390/min14010026 - 25 Dec 2023
Cited by 1 | Viewed by 2121
Abstract
A new strain of Leptospirillum sp. Ksh-L was isolated from a dump-bioleaching system of the Kashen copper-molybdenum mine (South Caucasus). Ksh-L is an obligate chemolithoautotroph, capable of oxidizing ferrous iron (Fe2+). Cells are Gram-negative and vibrio- or spirillum-shaped of a 0.5–3 [...] Read more.
A new strain of Leptospirillum sp. Ksh-L was isolated from a dump-bioleaching system of the Kashen copper-molybdenum mine (South Caucasus). Ksh-L is an obligate chemolithoautotroph, capable of oxidizing ferrous iron (Fe2+). Cells are Gram-negative and vibrio- or spirillum-shaped of a 0.5–3 µm size. The optimal conditions for the growth are 35 °C and pH 1.6–1.8. Cu2+ and Zn2+ have different effects on the oxidizing ability of the Leptospirillum sp. Ksh-L culture depending on the phase of growth and concentration of Fe2+. Under the conditions of gradually increasing the concentration of copper in the medium, during 4–5 successive subculturing experiments, it was possible to obtain an adapted culture of Leptospirillum sp. Ksh-L, capable of growing in the medium in the presence of up to 400 mM Cu2+. A bioleaching experiment indicates that Ksh-L can efficiently oxidize chalcopyrite. However, the bioleaching of copper from chalcopyrite by Leptospirillum ferrodiazotropum Ksh-L increased about 1.8 times in association with At. thiooxidans ATCC 19377. Phylogenetic analysis based on 16S rRNA gene sequences (GenBank ID ON226845) shows that strain Ksh-L forms a single cluster into Group III. The strain possesses 99.59%, 99.52%, and 96.60% sequence similarity with the strains YTW-96-06, YTW-66-06, and Leptospirillum ferrodiazotrophum 5C in Group III, respectively. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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16 pages, 3035 KiB  
Article
Automated Mineralogy and Diagnostic Leaching Studies on Bulk Sulfide Flotation Concentrate of a Refractory Gold Ore
by Mustafa K. Guner, Gülay Bulut, Ahmad Hassanzadeh, Stefanie Lode and Kurt Aasly
Minerals 2023, 13(10), 1243; https://doi.org/10.3390/min13101243 - 23 Sep 2023
Cited by 2 | Viewed by 2047
Abstract
Obtaining detailed and precise information from a classified refractory gold ore has been a long-standing challenge in mineral processing and process mineralogy. Although the concept of diagnostic leaching has been extensively addressed in the literature, very little information is available linking this approach [...] Read more.
Obtaining detailed and precise information from a classified refractory gold ore has been a long-standing challenge in mineral processing and process mineralogy. Although the concept of diagnostic leaching has been extensively addressed in the literature, very little information is available linking this approach with current advanced characterization techniques such as automated mineralogy. The present research study aims to characterize the flotation concentrate of refractory gold ore by combining diagnostic leaching and automated mineralogy to examine its processability. The diagnostic leaching process was applied stepwise at five stages, and the automated mineralogy was performed on different size fractions of the flotation concentrate. The chemical (X-ray fluorescence (XRF), atomic absorption spectroscopy (AAS), and inductively coupled plasma-optical emission spectroscopy (ICP-OES)) and mineralogical (X-ray diffraction (XRD)) analyses of the feed sample confirmed that the ore is a low-grade gold ore with 0.7 g/t Au. Initially, bottle roll tests were carried out to investigate leaching behavior, and the ore’s refractory nature, and gold recoveries of bottle roll tests in different sizes were below 40 wt%; it is classified as a high refractory gold ore as a result of direct cyanide leaching. Bulk sulfide flotation was applied to increase the gold content of the material. Automated mineralogy results demonstrated that most of the gold in the concentrate is present as an invisible gold form, and 63.7 wt% of gold was distributed in pyrite. Diagnostic leaching results showed 39.7 wt% of total gold was leachable using direct cyanide leaching, and around 33 wt% of undissolved gold was located in pyrite and arsenopyrite. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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17 pages, 4374 KiB  
Article
Study on Electrochemical Behavior of Oxidized Pyrite in Alkaline Electrolyte
by Yehao Huang, Zipei Jia, Wen Wang, Jia Yao, Runbo Gao, Laifu Xu, Hongtao Zhang, Yongsheng Zhang and Xiangyu Song
Minerals 2023, 13(8), 1070; https://doi.org/10.3390/min13081070 - 12 Aug 2023
Cited by 2 | Viewed by 1190
Abstract
Nowadays, refractory gold ore production around the world accounts for about 30% of total gold production, and the low leaching rate of such gold concentrate seriously limits the efficient utilization of gold resources. The alkaline preoxidation process can improve the leaching rate of [...] Read more.
Nowadays, refractory gold ore production around the world accounts for about 30% of total gold production, and the low leaching rate of such gold concentrate seriously limits the efficient utilization of gold resources. The alkaline preoxidation process can improve the leaching rate of this kind of gold deposit and has good development and application prospects. Therefore, it is of great significance to study the oxidation and dissolution behavior of pyrite in an alkaline environment. In this paper, the oxidation process of gold-bearing pyrite in an alkaline electrolyte was studied using electrochemical techniques, and the oxidation products of a pyrite electrode in an alkaline solution were characterized using XPS, SEM, and other analytical methods. The results show that the optimum pH for pyrite electrochemical oxidative dissolution is about 12, and the oxidation potential of pyrite should be above 0.8 V. In the process of alkaline oxidative dissolution of pyrite, part of the S element enters the electrolyte in the forms of Sx2−, S2O32−, SO32−, and SO42−, and a small amount of the S element is adsorbed on the surface of the electrode in the form of S0 and becomes a part of the passive layer. The Fe element is adsorbed on the surface of the electrode in the forms of Fe(OH)2, Fe2O3, and Fe2(SO4)3, which become the main components of the passivation layer. This study provides a theoretical basis and reference data for the chemical preoxidation treatment of gold-bearing sulfide ores. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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21 pages, 14233 KiB  
Article
Extraction of Gallium from Brown Corundum Dust by Roasting—Acid Leaching Process
by Juhua Zhang, Yuwei Chang, Cong Gao, Xujie Hui and Ari Jokilaakso
Minerals 2023, 13(7), 900; https://doi.org/10.3390/min13070900 - 1 Jul 2023
Cited by 2 | Viewed by 1345
Abstract
Brown corundum dust is a solid waste produced during the preparation of brown corundum with bauxite as the raw material. The dust has a relatively high gallium content; therefore, it is of great value to recover the gallium from this kind of dust. [...] Read more.
Brown corundum dust is a solid waste produced during the preparation of brown corundum with bauxite as the raw material. The dust has a relatively high gallium content; therefore, it is of great value to recover the gallium from this kind of dust. In this paper, a range of analysis and characterization methods, including XRD, XRF, SEM-EDS, and EPMA, were used to determine the occurrence of gallium. It was found that gallium was mainly present in the potassium-rich phase, wrapped by amorphous silicate and the corundum phase. Roasting activation followed by an acid leaching process was proposed to extract gallium from brown corundum dust. An investigation was carried out on the effects of roasting temperature, roasting time, and additive dosage on the recovery of gallium and the evolution of the phase composition of the dust. The results show that the roasting activation of sodium carbonate was better than that of calcium oxide. After roasting at 1073 K for 40 min with a sodium carbonate dosage of 0.5 (mass ratio of sodium carbonate to dust), the phase composition changed completely to mainly consist of sodium silicate, sodium aluminosilicate, and potassium aluminosilicate. In that case, around 93% of Ga could be recovered from the roasted dust through H2SO4 (4.6 mol/L) leaching for 90 min. The leaching process was described well by the kinetic equation of k3t = 1/(1 − α)1/3 − 1, with an apparent activation energy of 16.81 kJ/mol, suggesting that the leaching rate was limited by the transfer of leaching agent across the contacting interface of the dust particles. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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22 pages, 8773 KiB  
Article
Justification for Criteria for Evaluating Activation and Destruction Processes of Complex Ores
by Tatiana Aleksandrova, Nadezhda Nikolaeva, Anastasia Afanasova, Artyem Romashev and Valentin Kuznetsov
Minerals 2023, 13(5), 684; https://doi.org/10.3390/min13050684 - 17 May 2023
Cited by 4 | Viewed by 1392
Abstract
The mining industry is faced with the problem of depletion of reserves of easily beneficiated minerals containing valuable metals. The characteristic features of the ores involved in processing are fine dissemination; low content of valuable components; and similar physical, chemical, surface, and technological [...] Read more.
The mining industry is faced with the problem of depletion of reserves of easily beneficiated minerals containing valuable metals. The characteristic features of the ores involved in processing are fine dissemination; low content of valuable components; and similar physical, chemical, surface, and technological properties of minerals, among others. Under such conditions, increasing the efficiency of mineral processing becomes of primary importance. Creating highly efficient, environmentally safe technologies on the basis of deep study of the material, chemical, and mineralogical composition, as well as using and developing methods and techniques for testing mineral materials at successive stages of raw material transformation, enable to solve such problems. Criteria for assessing the flow of technological processes are presented in the article. A complex criterion is substantiated and proposed for quantitative assessment of the degree of physical and energy impact at the stages of ore preparation and flotation enrichment of mineral raw materials. The criterion is calculated on the basis of activation energy data calculated by differential and integral kinetic methods. In addition, an empirical indicator was introduced into the complex criterion, which allows increasing the accuracy of the calculated criterion. This criterion not only allows to estimate the degree of influence from the position of averaged estimation on the full interval of degrees of transformation from 0 to 1, but also gives the possibility to consider the required number of degrees of transformation; for example, if it is necessary to make estimations on narrow temperature intervals. The calculation of empirical parameters for the obtained criterion is carried out before and after the application of physical–energetic methods of influence using thermal analysis. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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10 pages, 6379 KiB  
Article
Mineral Phase Evolution during Oxidation Roasting Pretreatment of Typical Carlin Gold Ore and Effects on Gold Leaching Efficiency
by Licheng Ma, Xiang Liu, Lei Wang and Jungang Qi
Minerals 2023, 13(4), 558; https://doi.org/10.3390/min13040558 - 16 Apr 2023
Cited by 1 | Viewed by 2093
Abstract
Arsenious and sulphur-bearing micro-disseminated gold ore is a kind of typical refractory Carlin-Type. The gold in Carlin-Type gold ore grains is distributed finely, existing as invisible or submicroscopic gold, encapsulated in arsenopyrite and pyrite. The technical difficulty of treatment Carlin-Type gold ore lies [...] Read more.
Arsenious and sulphur-bearing micro-disseminated gold ore is a kind of typical refractory Carlin-Type. The gold in Carlin-Type gold ore grains is distributed finely, existing as invisible or submicroscopic gold, encapsulated in arsenopyrite and pyrite. The technical difficulty of treatment Carlin-Type gold ore lies in how to release the fine gold wrapped in pyrite and arsenopyrite. In this study, the oxidation roasting pre-treatment technique was used to treat the Carlin-Type gold ore. This included a two-stage roasting process: the arsenic was removed in the first roasting process, and the sulphur was removed in the second roasting process. The thermodynamic of the roasting process was analyzed, and the mineral phase evolution of the roasting process was investigated by using XRD, SEM and EDS. Finally, the influence of sodium cyanide dosage and leaching time on leaching efficiency was investigated. The results suggest that for the first roasting temperature at 550 °C, and the second roasting at temperature 700 °C with air flow 2.5 L/min, the sodium cyanide dosage is 1.75 kg/t and leaching time is 27 h; a good leaching efficiency is obtained with 83.85%. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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21 pages, 8054 KiB  
Article
Combined Physicochemical and Energy Methods to Improve the Recovery of Rare Earth Elements from Eudialyte Concentrate
by Valentine A. Chanturiya, Vladimir G. Minenko, Andrey L. Samusev, Maria V. Ryazantseva and Elizaveta V. Koporulina
Minerals 2023, 13(3), 414; https://doi.org/10.3390/min13030414 - 15 Mar 2023
Cited by 1 | Viewed by 1347
Abstract
The parameters for efficient nitric acid leaching were experimentally determined, which ensured the recoveries of Zr and REEs from eudialyte concentrate up to 87.0%–91.7% and 76.0%–81.1%, respectively. The possibility was shown of intensifying the leaching process through preliminary energy treatments to ensure the [...] Read more.
The parameters for efficient nitric acid leaching were experimentally determined, which ensured the recoveries of Zr and REEs from eudialyte concentrate up to 87.0%–91.7% and 76.0%–81.1%, respectively. The possibility was shown of intensifying the leaching process through preliminary energy treatments to ensure the intensive breakdown of mineral complexes and grains; as a result, the recovery of Zr and REEs increased by more than 10%. A process was developed for the selective recovery of up to 91.5% of zirconium and up to 71.2% of REEs in the form of carbonate compounds from the pregnant solution of nitric acid leaching by chemical precipitation as well as up to 81.1% REEs and up to 91.7% zirconium on hypercrosslinked polystyrene sorbents. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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11 pages, 2202 KiB  
Article
Substantiation of New Reagent Compositions for the Effective Extraction of Rhenium in the Processing of Complex Molybdenum Ores
by Valentine A. Chanturiya, Tamara N. Matveeva, Viktoriya V. Getman, Anna Yu. Karkeshkina and Nadezhda K. Gromova
Minerals 2023, 13(3), 372; https://doi.org/10.3390/min13030372 - 7 Mar 2023
Cited by 5 | Viewed by 1929
Abstract
Modern trends in technological improvement for producing high-quality rhenium-containing molybdenum concentrates are aimed at developing environmentally friendly solutions com-pared to traditional ones, involving a reduction in consumption or complete replacement of toxic substances and the use of plant reagents and microorganisms and make [...] Read more.
Modern trends in technological improvement for producing high-quality rhenium-containing molybdenum concentrates are aimed at developing environmentally friendly solutions com-pared to traditional ones, involving a reduction in consumption or complete replacement of toxic substances and the use of plant reagents and microorganisms and make it possible to eliminate energy-intensive processes of steaming and roasting. It is known that up to 25%–30% of Mo, Cu and Re goes to rough flotation tailings and is lost in wastes. Those losses are a consequence of the ore composition variability, chalcopyrite–molybdenite ratio, an increase in the proportion between primary copper sulfide and finely disseminated molybdenite and the recovery of floating pyrite. High rates of valuable metal recovery into bulk concentrate can be achieved by using new compositions of flotation reagents that selectively change the hydrophobic properties of the target minerals. The application of new reagent compositions, including novel chemicals—dithiopyrylmethane (DTM), composite reagent (CR) and conventional butyl xanthate (ButX)—was theoretically and experimentally substantiated for the effective rhenium extraction in the processing of hard-to-beneficiate complex molybdenum ores. It is identified that DTM forms a complex DTM–Re compound and chemically adsorbed on rhenium-containing molybdenite providing an increase in Re recovery into the bulk Cu–Mo–Re concentrate by 17%, reducing by two times the loss of rhenium with flotation tailings, and the subsequent 97.6% Re extraction of the molybdenum concentrate by autoclave leaching. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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15 pages, 2565 KiB  
Article
Acid Resistance and Ion-Exchange Capacity of Natural Mixtures of Heulandite and Chabazite
by Vladimer Tsitsishvili, Marinela Panayotova, Nato Mirdzveli, Nagima Dzhakipbekova, Vladko Panayotov, Nanuli Dolaberidze and Manana Nijaradze
Minerals 2023, 13(3), 364; https://doi.org/10.3390/min13030364 - 4 Mar 2023
Cited by 6 | Viewed by 1852
Abstract
The recovery and immobilization of metals from wastewater often occurs in an acidic environment that destroys the structure of adsorbents such as zeolites, which are porous crystalline aluminosilicates. The influence of hydrochloric acid solutions on the structure and properties of two natural mixtures [...] Read more.
The recovery and immobilization of metals from wastewater often occurs in an acidic environment that destroys the structure of adsorbents such as zeolites, which are porous crystalline aluminosilicates. The influence of hydrochloric acid solutions on the structure and properties of two natural mixtures of heulandite (HEU) and chabazite (CHA)—tuff from the Georgian Dzegvi-Tedzami deposit (HEU/CHA ≈ 8) and rock from the Kazakhstani deposit Chankanay (HEU/CHA≈1)—was studied by the X-ray energy dispersion spectra and diffraction patterns, as well as by adsorption of water, benzene, and nitrogen methods. It was found that acid-mediated dealumination, decationization, dissolution, and changes in systems of micro- and mesopores depend on the nature and chemical composition of the initial zeolites. It is concluded that, under the influence of acid, (i) zeolite micropores become accessible to relatively large molecules and ions, and the surface area of the adsorbent increases; (ii) the volume of mesopores decreases, and pores with a diameter of less than 4 nm become predominant; (iii) in terms of the degree of dealumination and dissolution rate, Kazakhstani zeolite is more acid-resistant than Georgian heulandite; and (iv) Kazakhstani zeolite retains a high ion-exchange capacity in an acidic environment, while Georgian heulandite, treated with dilute hydrochloric acid solutions, uptakes relatively high amounts of valuable silver, copper, and zinc. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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11 pages, 6441 KiB  
Article
Gold Extraction from a Refractory Sulfide Concentrate by Simultaneous Pressure Leaching/Oxidation
by Juan Carlos Soto-Uribe, Jesus Leobardo Valenzuela-Garcia, Maria Mercedes Salazar-Campoy, Jose Refugio Parga-Torres, Guillermo Tiburcio-Munive, Martin Antonio Encinas-Romero and Victor Manuel Vazquez-Vazquez
Minerals 2023, 13(1), 116; https://doi.org/10.3390/min13010116 - 12 Jan 2023
Cited by 4 | Viewed by 4994
Abstract
Most gold deposits occur associated with sulphides like pyrite and arsenopyrite; thus, precious metal dissolution is possible by oxidizing auriferous sulfide concentrate using simultaneous pressure oxidation and cyanidation. The effectiveness of this process of extraction can be influenced by the temperature, cyanide (NaCN) [...] Read more.
Most gold deposits occur associated with sulphides like pyrite and arsenopyrite; thus, precious metal dissolution is possible by oxidizing auriferous sulfide concentrate using simultaneous pressure oxidation and cyanidation. The effectiveness of this process of extraction can be influenced by the temperature, cyanide (NaCN) concentration, and oxygen pressure. In this study, we conducted experiments to characterize the effects on gold extraction of ores using a range of sodium cyanide concentrations (1–8 g/L), temperatures (40–75 °C), and oxygen pressures (0.5–1.1 MPa). Characterization of the ores showed that pyrite and quartz were the main minerals present in the concentrate. The best results in terms of the highest extraction of Au were obtained with an oxygen pressure of 0.5 MPa, 6 g/L sodium cyanide, and a temperature of 75 °C, along with a constant stirring speed of 600 rpm. These conditions allowed for approximately 95% gold extraction in 90 min. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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11 pages, 3951 KiB  
Article
Effects of Different Grinding Media and Milling Conditions on the Flotation Performance of a Copper-Pyrite Ore
by N. Metin Can and Çağrı Başaran
Minerals 2023, 13(1), 85; https://doi.org/10.3390/min13010085 - 5 Jan 2023
Cited by 5 | Viewed by 2155
Abstract
Different milling conditions, such as wet or dry, and use of different grinding media have a great impact on the flotation performance of sulphide minerals. In the present study, the effects of wet and dry grinding and the use of different grinding media, [...] Read more.
Different milling conditions, such as wet or dry, and use of different grinding media have a great impact on the flotation performance of sulphide minerals. In the present study, the effects of wet and dry grinding and the use of different grinding media, such as mild steel (MS) and stainless steel (SS), were investigated on a Cu-sulphide ore. The samples were ground as dry and wet with both grinding media, to a P80 value of −75 µm, and then flotation was carried out under the same conditions. The obtained data from flotation were evaluated in terms of solid/water recovery, chalcopyrite/pyrite recovery and separation efficiency. The effects of different milling conditions were discussed with the measured chemical parameters such as redox potential and dissolved oxygen level together with the flotation rate of chalcopyrite. The redox potential of the dry ground ore, irrespective of the type of milling media, was measured considerably higher than the wet grinding conditions. With SS media flotation, the rate of Cu was high for dry grinding, resulting in a higher selective concentrate in terms of grade. However, Cu recovery was lower due to the instability of the froth structure. Separation efficiency pointed out that the best flotation performance could be obtained using a wet grinding condition with MS balls. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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25 pages, 8341 KiB  
Article
Cost-Effective and High Purity Valuable Metals Extraction from Water Leaching Solid Residues Obtained as a By-Product from Processing the Egyptian Boiler Ash
by Ahmed H. Ibrahim, Xianjun Lyu, Bahig M. Atia, Mohamed A. Gado and Amr B. ElDeeb
Minerals 2022, 12(9), 1084; https://doi.org/10.3390/min12091084 - 27 Aug 2022
Cited by 7 | Viewed by 2134
Abstract
The water leaching solid residues (WLSR) obtained from salt-roasting Egyptian boiler ash are considered an essential secondary resource for (13%) nickel and (5.6%) zinc extraction. Hence, the current study aims for the cost-effective and high purity Ni, Zn, Fe and Mg metal ion [...] Read more.
The water leaching solid residues (WLSR) obtained from salt-roasting Egyptian boiler ash are considered an essential secondary resource for (13%) nickel and (5.6%) zinc extraction. Hence, the current study aims for the cost-effective and high purity Ni, Zn, Fe and Mg metal ion extraction from (WLSR) using a sulfuric acid leaching process. The factors affecting the percentage recovery of Ni, Zn, Fe and Mg from WLSR, including leaching temperature, time, acid concentration and solid/liquid ratio, have been investigated. The obtained leaching solutions were analyzed chemically using ICP, and the different precipitates were analyzed mineralogically using XRD and EDX analysis and chemically using XRF. The maximum percentage recovery of Ni, Zn, Fe and Mg was 95.02%, 90.13%, 66.29% and 75.73%, which was obtained under the optimum leaching conditions of 8% H2SO4 concentration and 1/15 solid/liquid ratio at 85 °C for 240 min. The effect of pH, Fe2O3 dosage as nucleating agent and the precipitation duration on iron removal and Ni and Zn loss have been thoroughly studied. It has been found that >95% of the contained iron impurity can be removed, while nickel and zinc losses are around 4.2% and 3.8%, respectively. Additionally, a pH of 6 and 0.45 mol/L concentration of H2C2O4 was utilized to precipitate Mg as MgC2O4.2H2O, demonstrating that the precipitation efficiency of Mg reaches 96.9%. Nickel and zinc precipitation efficiency was 92.25% and 85.51%, respectively, by raising the solution pH to approximately 9. The kinetic of Ni and Zn dissolution has been investigated to explain the mechanism prevalent and the factors influencing the leaching process. It has been found that the nickel leaching kinetic is controlled by both diffusion through an inert porous layer and by chemical reaction with an activation energy of 20.25 kJ.mol−1. Meanwhile, the kinetic of zinc leaching is controlled by solid product layer diffusion with an activation energy of 11.67 kJ mol−1. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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Review

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27 pages, 3222 KiB  
Review
Kenya’s Mineral Landscape: A Review of the Mining Status and Potential Recovery of Strategic and Critical Metals through Hydrometallurgical and Flotation Techniques
by Nelson R. Kiprono, Tomasz Smoliński, Marcin Rogowski, Irena Herdzik-Koniecko, Marcin Sudlitz and Andrzej G. Chmielewski
Minerals 2024, 14(1), 21; https://doi.org/10.3390/min14010021 - 24 Dec 2023
Cited by 3 | Viewed by 5912
Abstract
Kenya is an East African country with the third-largest economy in sub-Saharan Africa. The demand for metals and minerals continues to increase due to urbanization, population rise, and new infrastructure growth in different countries. Kenya formally confirmed the discovery of oil and various [...] Read more.
Kenya is an East African country with the third-largest economy in sub-Saharan Africa. The demand for metals and minerals continues to increase due to urbanization, population rise, and new infrastructure growth in different countries. Kenya formally confirmed the discovery of oil and various minerals in April 2013, launching itself as a new player in Africa’s rapidly expanding extractive sector. This review paper highlights the mining status in Kenya and the role of hydrometallurgical and flotation processes in the recovery of deficit metals from ores and mine wastes. The nation’s 2030 Vision is anticipated to benefit greatly from the proceeds from the sale of oil, gas, and valuable metals. Because Kenya was originally mapped as an agricultural region, less mineral prospecting was done in earlier times. The country’s mining industry is now dominated by the manufacture of non-metallic goods, and it is largely neglected for minerals. One of the most serious problems for the mining industry in Kenya is the production of tailings that hold strategic metals. The material is already ground, which means the most energy-consuming process has been already applied, and chemical engineering processes like leaching are more feasible at this point. Hydrometallurgical and flotation recovery of valuable metals from wastes, high and low-grade ores, or tailings is essential. The resources will be preserved, which ensures sustainability in the growth of the mining industry. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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44 pages, 3332 KiB  
Review
Control of Non-Ferrous Metal-Sulfide Minerals’ Flotation via Pulp Potential
by Marinela Panayotova
Minerals 2023, 13(12), 1512; https://doi.org/10.3390/min13121512 - 1 Dec 2023
Cited by 3 | Viewed by 1929
Abstract
Studies on the dependence of the technological results of non-ferrous sulfide ore (copper—arsenic-bearing and non-arsenic-bearing—lead–zinc, and polymetallic) flotation on the pulp potential Eh are reviewed. Findings on the relation of Eh and collectorless flotation are presented. Changes in the pulp potential due to [...] Read more.
Studies on the dependence of the technological results of non-ferrous sulfide ore (copper—arsenic-bearing and non-arsenic-bearing—lead–zinc, and polymetallic) flotation on the pulp potential Eh are reviewed. Findings on the relation of Eh and collectorless flotation are presented. Changes in the pulp potential due to different gas applications and various reagent additions are considered. The influence of the grinding medium on the pulp Eh and hence on the flotation results is presented through various examples. The relation between the oxidation–reduction potential and reagent effects is exhibited and explained. pH–Eh ranges of different minerals’ flotation, as recorded in various studies, are summarized and visualized jointly for all mentioned ores. It is concluded that the pulp Eh value, considered together with the pH value, is a useful means for flotation selection controlling and deserves further research, especially under industrial conditions. Some problems and difficulties in using pulp Eh for flotation control are discussed. Full article
(This article belongs to the Special Issue Valuable Metals Recovery by Mineral Processing and Hydrometallurgy)
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