Hydrometallurgy最新文献

{"title":"Technological advancements in rare earth elements recovery from ionic clays: A comprehensive review","authors":"Gisele Azimi","doi":"10.1016/j.hydromet.2024.106414","DOIUrl":"10.1016/j.hydromet.2024.106414","url":null,"abstract":"<div><div>The growing demand for rare earth elements, pivotal for modern technologies, has necessitated the development of efficient and sustainable extraction methods from ionic clays. This review provides a comprehensive analysis of the advancements in rare earth recovery from ionic clays, focusing on the geological, geochemical, and technological aspects of the extraction processes. Historically, traditional methods of extracting rare earths from mineral ores have been environmentally detrimental and economically intensive due to their complex multi-step procedures and the handling of radioactive materials. In contrast, ionic clays, primarily found in weathered crusts of granite and volcanic rocks, offer a more accessible source of rare earths, particularly heavy rare earth elements (HREEs), through simpler ion exchange processes. The necessity to discuss this topic arises from the increasing environmental and economic pressures to find greener and more sustainable methods of rare earth extraction. The review highlights the transition towards environmentally friendly leaching agents, such as non-ammonium salts, and the integration of advanced techniques like microbial adsorption and solvent extraction. These innovations aim to enhance extraction efficiency while reducing ecological footprints. Additionally, the review highlights the importance of understanding the geological conditions that favor the formation of ionic rare earth deposits, such as climate, topography, and geological history, which are critical for efficient prospecting and exploitation. Moreover, the paper presents a life cycle analysis of <em>in-situ</em> leaching of rare earths from ionic clays, a method that minimizes surface disruption and environmental impact compared with conventional mining. The efficacy of this method is evaluated through case studies and field implementations, demonstrating significant improvements in efficiencies of recovery and operational sustainability. In conclusion, this review emphasizes the strategic importance of rare earth extraction from ionic clays, not only to meet the rising global demand but also to support the advancement of green technologies essential for a sustainable future. It calls for continued research into alternative extraction technologies and methods that balance economic feasibility with environmental responsibility, ensuring the sustainable exploitation of these critical resources.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106414"},"PeriodicalIF":4.8,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142538415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lipophilic EDTA-based ligands in different diluents for the extraction of rare earths: Preliminary results with Nd(III), Dy(III) and Pr(III) in chloride and nitrate media","authors":"Tamir Sukhbaatar ,&nbsp;Raphaëlle Piton ,&nbsp;Fabrice Giusti ,&nbsp;Guilhem Arrachart ,&nbsp;Magali Duvail ,&nbsp;Aarti Kumari ,&nbsp;Santosh Daware ,&nbsp;Shally Gupta ,&nbsp;Sriram Goverapet ,&nbsp;Sushanta Kumar Sahu ,&nbsp;Beena Rai ,&nbsp;Stéphane Pellet-Rostaing","doi":"10.1016/j.hydromet.2024.106415","DOIUrl":"10.1016/j.hydromet.2024.106415","url":null,"abstract":"<div><div>A separation method for the recovery of neodymium(III) from two different media, chloride and nitrate, by implementing solvent extraction technique with a novel lipophilic diamide derivative of ethylenediamine tetraacetic acid (EDTA), namely 2,2’-<em>N</em>,<em>N</em>′-didecyl-dioxo-<em>N</em>,<em>N′</em>,<em>N″</em>,<em>N″’</em>-tetraazatetratriacontane-<em>N″</em>,<em>N″’</em>-diyl diacetic acid (<strong>H</strong>_{<strong>2</strong>}<strong>E-4C</strong>_{<strong>10</strong>}), has been investigated. Initial screening results demonstrated acceptable solubility (ca. 15 mM) of the diamide in 1,3-diisopropylbenzene (DiPB) and in a 93:7 v:v <em>n</em>-dodecane:<em>n</em>-octanol mixture (DOm) as non-polar diluents. Further investigations aiming at determining operational parameters associated with the befitted extractant systems were conducted at pH ranging from 2 to 4 in chloride and nitrate media. A pH-dependent performance of the proposed systems revealed loading capacity peaking at pH = 3 with the respective values of 1.7 and 2.0 g L⁻¹ in nitrate and chloride media. The extraction efficiency, the distribution coefficients, and the separation factor (<em>E</em>_%, <em>D</em> and <em>SF</em>, respectively) were determined for an equimolar mixture of neodymium (Nd) and two other potential competitive lanthanides, namely dysprosium (Dy) and praseodymium (Pr). The best selectivity was observed in the chloride medium at pH = 4 yielding <em>SF</em>_Nd/Pr = 1.48 and <em>SF</em>_Nd/Dy = 2.03. Neodymium-to-extractant stoichiometry was evidenced in chloroform to be 1:1 H₂E:Nd at pH = 2. Thermodynamic constants related to the considered extraction equilibrium have been determined by using the Van't Hoff relation and the slope analysis method. It appeared within the selected pH-range that the mechanism of the Nd³⁺ transfer was strongly influenced by the nature of the diluent. This was illustrated by the enthalpy-driven transfer when Nd³⁺ was extracted with the <strong>H</strong>_{<strong>2</strong>}<strong>E-4C</strong>_{<strong>10</strong>}-Dom system (aliphatic diluent) while the transfer became entropy-driven when the extraction was performed with the <strong>H</strong>_{<strong>2</strong>}<strong>E-4C</strong>_{<strong>10</strong>}-DiPB system (aromatic diluent). The complexation of Nd³⁺ involved mainly the participation of both the amide and carboxylic functional groups. The transfer of the cation to the organic phase might occur through the formation of the Nd(<em>HE</em>)<em>A</em>₂ complex (where <em>A</em> is either a nitrate or a chloride anion), allowing for the lowest associated standard Gibbs free energy of transfer (−28 &lt; <em>ΔG</em>° &lt; −24 kJ mol⁻¹) regardless of the aqueous feed.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106415"},"PeriodicalIF":4.8,"publicationDate":"2024-10-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Separation of yttrium from ion-adsorbed-rare-earth deposit leachates using N,N-di(2-ethylhexyl)-diglycolamic acid (HDEHDGA): Preliminary experimental and molecular dynamics simulation studies","authors":"Chunhua Wang ,&nbsp;Runhan Yan ,&nbsp;Hongmin Cui ,&nbsp;Jinsong Shi ,&nbsp;Nanfu Yan ,&nbsp;Shengyong You","doi":"10.1016/j.hydromet.2024.106412","DOIUrl":"10.1016/j.hydromet.2024.106412","url":null,"abstract":"<div><div>The separation of yttrium (Y) from heavy rare-earth elements (HREEs) is a major issue for ion-adsorbed rare-earth deposits. This study describes a new extraction system to develop efficient separation of Y from HREEs in a chloride medium using diglycolamic acid as the extractant. The extraction performance of <em>N</em>,<em>N</em>-di(2-ethylhexyl)-diglycolamic acid (HDEHDGA) for mixed REEs of an ion-adsorbed rare-earth deposit was investigated. The extraction order of the REEs in the HDEHDGA system followed a positive sequence, and the extraction behavior of Y resembled that of the middle REEs. Compared with naphthenic acid (NA) and sec-octylphenoxy acetic acid (CA12), HDEHDGA exhibited better separation performance for HREEs (Ho-Lu) and Y. The separation factors of Ho/Y, Er/Y, Tm/Y, Yb/Y, and Lu/Y in the Y-enriched solution were 4.41, 4.29, 3.77, 3.26, and 3.11, respectively. Combined slope analysis and electrospray ionization–high-resolution mass spectroscopy (ESI-HRMS) results identified cation exchange as the extraction mechanism of RE³⁺. Furthermore, the molecular dynamics simulation results provided new insights into the dynamic behaviors of Y³⁺ and Yb³⁺ extraction and revealed that the interaction of HDEHDGA with Yb³⁺ was stronger than that with Y³⁺. In addition, the loading capacity and recyclability of HDEHDGA were evaluated. This study highlights the potential of the HDEHDGA system for the separation of Y from HREEs.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106412"},"PeriodicalIF":4.8,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A critical review of hydrothermal treatment of sulfide minerals with Cu(II) solution in H2SO4 media","authors":"Aleksei Kritskii ,&nbsp;Gerardo Fuentes ,&nbsp;Haci Deveci","doi":"10.1016/j.hydromet.2024.106413","DOIUrl":"10.1016/j.hydromet.2024.106413","url":null,"abstract":"<div><div>Hydrothermal pretreatment of copper concentrates in acidified copper sulfate solution has been known since the beginning of the last century as an approach to the chemical enrichment of copper concentrates. While the pilot-scale demonstration of this approach exists, detailed investigations into the underlying chemical interactions that form the basis of this technology are rarely available in open sources. This review attempts to summarize research data on the hydrothermal treatment of sulfide minerals for over a century. It focuses on the hydrothermal interactions between acidified copper sulfate solution and sulfide minerals, which are of key significance for the hydrothermal enrichment process, including the main copper minerals (CuFeS₂, Cu₅FeS₄, CuS, Cu₂S) and those (e.g., ZnS, FeS_2, and PbS) that are often associated with copper concentrates as penalty impurities. Studies on the hydrothermal enrichment of various sulfide raw materials (including copper concentrates) have shown that parameters such as temperature, the concentration of reagents, and the molar ratio of Cu in solution to Cu in solid, among others, influence the efficiency of the process.</div><div>Furthermore, reaction kinetics seem to assume prime importance in controlling the hydrothermal treatment process. High activation energies, fractional orders of the reactions with respect to the reagents, and diffusion-controlled kinetics characterize the hydrothermal interactions between sulfides and acidified copper sulfate solution. The findings in the literature were critically examined and discussed with the delineation of further research needs.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106413"},"PeriodicalIF":4.8,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142554467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fundamentals of copper(II) adsorption on phyllosilicate minerals relevant to crud formation in solvent extraction from heap leach liquors","authors":"J. Valenzuela-Elgueta ,&nbsp;A.V. Delgado ,&nbsp;S. Ahualli","doi":"10.1016/j.hydromet.2024.106409","DOIUrl":"10.1016/j.hydromet.2024.106409","url":null,"abstract":"<div><div>Because of the common presence of different silicate minerals, like kaolinite, montmorillonite and muscovite as gangue minerals in the beneficiation of copper oxide ores, the interaction between copper(II) ions in solution and each of these minerals is a field of strong interest, considering their implications on the aggregation of these minerals in the extreme pH conditions typical of hydrometallurgical unit operations for copper production. After copper adsorption isotherms determination at pH 2 and 4, specific adsorption data were fitted to both Langmuir and Freundlich models. It was found that adsorption is systematically larger at pH 4, and that montmorillonite is the mineral that displays a larger adsorption capacity, as in principle expected by its larger cation exchange capacity, CEC. A good fitting to the Langmuir model was obtained for the three samples, and montmorillonite also appears to conform to Freundlich isotherm predictions, as the tested concentrations of copper(II) do not allow to reach saturation. Furthermore, some desorption is measured for kaolinite and muscovite at the highest copper concentrations, probably because of significant interactions between the adsorbed ions. No such desorption was detected in montmorillonite samples. An XPS analysis of the surfaces of the three minerals suggests that copper adsorption in kaolinite is not associated to a cation exchange process but rather to electrostatic interactions between silica-like faces of the clay. In contrast, ionic exchange of structural calcium (for montmorillonite) or potassium (in the case of muscovite) seems to be the predominant mechanism of Cu(II) adsorption in the other two samples. Electrophoretic mobility determinations agree with this hypothesis: the mobility (always negative, with no traces of charge inversion) decreases in absolute value when kaolinite particles are in contact with solutions of increasing copper concentration at pH 2 or pH 4. On the other hand, the electrophoretic mobility values of muscovite and montmorillonite showed a weak pH and copper concentration dependence, a result that matches well with the ion exchange processes detected in the XPS measurements.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106409"},"PeriodicalIF":4.8,"publicationDate":"2024-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Separation of hafnium from zircon leach solution using anion-exchange resin and production of high-purity zirconia for nuclear applications","authors":"Z.H. Ismail,&nbsp;S.E. Rizk,&nbsp;E.M. Abu Elgoud,&nbsp;H.F. Aly","doi":"10.1016/j.hydromet.2024.106411","DOIUrl":"10.1016/j.hydromet.2024.106411","url":null,"abstract":"<div><div>The ion exchange process using an anion exchange resin (Bio-Rex 5) was employed with batch and column techniques to isolate nuclear-grade zirconium/hafnium from a leach solution of zircon ore. Batch studies were conducted to optimize the conditions for sorption and desorption of Zr(IV) and Hf(IV). The highest separation factor of 10.3 was achieved under equilibrium conditions of 11.0 mol/L HCl, contact time of 30.0 min, solution volume-to-mass of resin ratio of 0.10, and 15 °C. The sorption process for both metals obeyed a pseudo-second-order model and the experimental sorption data was well-described by both Langmuir and Freundlich models. The maximum sorption capacities were determined to be 46.2 mg/g for Zr(IV) and 37.8 mg/g for Hf(IV). The Zr(IV) and Hf(IV) ions were effectively desorbed by 0.1 mol/L nitric and 2.0 mol/L hydrochloric acid solutions, respectively, with total yields of 89.7 % Zr(IV) and 85.8 % Hf(IV) via multistage desorption processes. In both batch and column techniques, the resin exhibited sorption selectivity for Zr and Hf over interfering elements in the hydrochloric acid leach solution of zircon sand. The loaded resin from real leach solution was subjected to desorption, zirconium sulfate precipitation, and calcination at 650  °C, resulting in a pure zirconia powder suitable for nuclear applications. This technique presents a promising effective method for the selective separation and recovery of high-purity zirconium and hafnium from their natural sources.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106411"},"PeriodicalIF":4.8,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142534602","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enhancement of gold extraction by citric acid-assisted microwave roasting of Carlin-type gold ores and sulfide/thiosulfate leaching","authors":"Tiantian Wu ,&nbsp;Zhihui Shen ,&nbsp;Zhenwu Shi ,&nbsp;Jianlong Wang ,&nbsp;Yueqin Qiu ,&nbsp;Song Mao","doi":"10.1016/j.hydromet.2024.106410","DOIUrl":"10.1016/j.hydromet.2024.106410","url":null,"abstract":"<div><div>The occurrence of most gold in an encapsulated state often results in poor extraction efficiency, and efficient pretreatment is the key to effective gold recovery from Carlin-type gold ores. This study investigated the enhancement of citric acid (CA) assisted microwave (MW) roasting on gold extraction from Carlin-type gold ores by sulfide/thiosulfate leaching, primarily analyzing in-situ phase transformation, microstructure characterization, and the thermal decomposition behavior of solids. The results show that gold extraction increases significantly with increasing CA dosage, furnace temperature, and roasting time when heated by MW, reaching a maximum of 87.7% at a CA dosage of 2% and a temperature of 500°C for 60 min in the presence of air. Moreover, extraction is significantly higher with CA than without CA at roasting temperatures below 300°C. The phase transition of gold-bearing pyrite is controlled mainly by temperature when heated by MW without CA, resulting in surface oxidation at 300°C, with significant oxidation at 400°C, and complete transformation into Fe₂O₃ and SO₂ at temperatures over 500°C. Interestingly, CA and its decomposition products of CO₂ and H₂O induce the generation of unstable intermediates at 100°C, such as FeCO₃, FeC₂₁H₂₁O₇, and FeOOH. The decomposition of these intermediates at higher temperatures results in the rapid formation of a hematite layer with developed pores at 300°C, which provides more diffusion channels for SO₂ and O₂, producing coral-like porous hematite particles. Both number of pores and the pore size are larger at 500°C. The combined effect of MW and CA enhances exposed gold content over 70% which in turn increases gold extraction. This work provides significant insights into the enhancement process of gold extraction of CA-assisted MW roasting.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106410"},"PeriodicalIF":4.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142433066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Efficient recovery of organic phase from crud in solvent extraction unit of Sarcheshmeh copper complex in Iran by powerful water-absorbent reagents","authors":"Mohammad Anary-Abbasinejad ,&nbsp;Zahra Manafi ,&nbsp;Fatemeh Zamani ,&nbsp;Parisa Salarizadeh ,&nbsp;Mehri Shahhoseini ,&nbsp;Fereshteh Vahedi ,&nbsp;Seyed Ali Seyedbagheri","doi":"10.1016/j.hydromet.2024.106408","DOIUrl":"10.1016/j.hydromet.2024.106408","url":null,"abstract":"<div><div>The formation of stable multi-phase emulsions (crud) is a serious problem in almost all commercial solvent extraction (SX) plants. Crud is a mixture of organic and aqueous phases, air, and organic or inorganic solid particles, often found to distribute itself randomly throughout the separating phases of SX plants. Crud formation is encountered in almost all SX units in metal extraction plants. It causes the loss of solvent and thus increases the process costs. Therefore, the removal of crud and recovery of the expensive organic phase including diluent and extracting reagents from it is of great importance. In this research, the applicability of a range of powerful water absorbent reagents was studied for the recovery of organic phase from the crud formed in copper extraction/electrowining unit of Sarchashmeh copper complex (IRAN). The reagents included gypsum, carbomer, sodium polyacrylate, sodium sulfate, magnesium sulfate and calcium chloride. The results showed that gypsum, carbomer and sodium polyacrylate are effective additives which let the organic phase to be recovered with up to 95 % yield. To ensure that gypsum does not cause a negative effect on the copper loading and stripping of the recovered solvent, the extraction/stripping properties of the organic phase separated with gypsum was compared with the organic phase separated by centrifugation without additives. Surface tension analysis of the gypsum-recovered organic phase also confirmed its suitability for recovery of organic phase from crud. Finally, the calcium content of gypsum-recovered organic phase was measured and compared with that of the organic phase separated by centrifugation without any additive.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106408"},"PeriodicalIF":4.8,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The combined leaching of copper, gold and uranium in chloride solutions. II. Concentrate leach tests","authors":"M. Nicol ,&nbsp;K. Ye ,&nbsp;N. Garrard","doi":"10.1016/j.hydromet.2024.106407","DOIUrl":"10.1016/j.hydromet.2024.106407","url":null,"abstract":"<div><div>This study of the simultaneous leaching of copper, gold and uranium from a flotation concentrate is aimed at establishing the conditions that could be applied in a possible heap leach process that would recover all three metals (plus silver, if present) in a single step. The results obtained in this study confirm the results obtained in Part I (Nicol et al., 2024) that enhanced rates for leaching of chalcopyrite from flotation concentrates from two different sources can be obtained in acidic chloride solutions in the presence of chlorate ions. The measurements of the solution potentials during leaching with chlorate are similar to those obtained previously and confirm that chlorine generated by the chlorate-chloride reaction is the active oxidant.</div><div>Uranium is dissolved even in the absence of chlorate by iron(III) as the oxidant. The latter is re-generated by reaction of iron(II) with chlorate. The dissolution of gold requires higher potentials, and it is only leached when the potential approaches 1.0 V in concentrated chloride solutions. At low chloride concentrations (1 M), gold is not dissolved because of apparent passivation.</div><div>An electrochemical study of the behaviour of gold in chloride solutions in the presence of sulfide ions has shown that the passivation is probably the result of the formation of a layer of Au₂S on the gold surface at low potentials before the addition of chlorate to the leach solutions i.e., before the generation of sufficient chlorine concentrations. At potentials above about 0.95 V Au₂S is unstable being oxidised to AuCl₂⁻ and elemental sulfur thereby eliminating passivation.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106407"},"PeriodicalIF":4.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The combined leaching of copper, gold and uranium in chloride solutions. I. Chalcopyrite","authors":"M. Nicol ,&nbsp;K. Ye ,&nbsp;N. Garrard","doi":"10.1016/j.hydromet.2024.106406","DOIUrl":"10.1016/j.hydromet.2024.106406","url":null,"abstract":"<div><div>In a study (Part II) aimed at the simultaneous heap leaching of copper (predominantly chalcopyrite), gold and uranium from an ore, it was found that this could be achieved using chlorate as the oxidant in chloride solutions. As a result, a more detailed study has been made using electrochemical and batch leach tests on pure chalcopyrite electrodes under typical heap leach conditions.</div><div>The use of chlorate at moderately low concentrations has shown that enhanced rates of dissolution of chalcopyrite can be maintained over periods up to 4 days at ambient temperatures in acidic chloride solutions. The rate of dissolution is enhanced at higher acid concentrations. The rate in the presence of chlorate does not appear to depend on the iron(III) (and presumably the copper(II)) concentration.</div><div>The observed rates are significantly greater than those predicted for oxidative dissolution from the electrochemistry and the mixed potential model. An alternative non-oxidative mechanism has been revisited to account for this difference.</div><div>A preliminary measurement has been made of the kinetics of the oxidation of hydrogen sufide and iron(III) by low concentrations of chlorine produced by reaction of chlorate with chloride ions. These reactions are rapid, and theory shows that they would support the proposed non-oxidative mechanism.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"231 ","pages":"Article 106406"},"PeriodicalIF":4.8,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421715","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}