Hydrometallurgy最新文献

{"title":"High-pressure acid leaching of laterite ores: Effect of acid and solid content on Ni and Co yield under non-isothermal and isothermal conditions","authors":"Okechukwu Vincent Dickson ,&nbsp;Thomas Deleau ,&nbsp;Fabienne Espitalier ,&nbsp;Christophe Coquelet ,&nbsp;Julien Lombart ,&nbsp;Philippe Accart","doi":"10.1016/j.hydromet.2025.106576","DOIUrl":"10.1016/j.hydromet.2025.106576","url":null,"abstract":"<div><div>The increasing demand for nickel (Ni) in electric vehicle batteries necessitates efficient extraction methods from laterite ores. High-Pressure Acid Leaching (HPAL) is a prominent hydrometallurgical technique known for its rapid kinetics and high (&gt;90 %) metal dissolution. This study examines the influence of acid-to-ore (A/O) ratios (0.25, 0.35, and 0.45) and slurry solid contents (22, 26, and 30 wt.%) on Ni yield and selectivity under both non-isothermal (100 °C, 1.2 bar; 150 °C, 4.7 bar; 200 °C, 18.9 bar; 265 °C, 50.5 bar) and isothermal (265 °C) conditions.</div><div>Under non-isothermal conditions, Ni leaching efficiency improved with temperature, achieving a maximum yield of 94.67 ± 0.02 wt.% at 265 °C, compared to 50.86 ± 0.02 wt.% at 200 °C, using an A/O ratio of 0.45 and 26 wt.% solids over 60 min. Isothermal experiments at 265 °C revealed that higher A/O ratios enhanced Ni yield, reaching 94.45 ± 0.01 wt.% at 60 min with 26 wt.% solids and an A/O of 0.45. However, this increased yield was accompanied by higher dissolution of Fe (1.07 ± 0.12 wt.%) and Al (38.84 ± 0.07 wt.%), reducing selectivity to 0.73 ± 0.01. Conversely, an A/O ratio of 0.25 at 26 wt.% solids achieved a higher selectivity of 3.83 ± 0.05 but with a lower Ni yield of 79.14 ± 0.03 wt.%. Lower slurry solid content further improved Ni leaching; at 22 wt.% solids and an A/O of 0.45, Ni yield reached 95.87 ± 0.01 wt.% with a selectivity of 0.89 ± 0.02 at 60 min.</div><div>Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) analyses of leached residues indicated that high temperatures facilitate the transformation of primary minerals like goethite and gibbsite into hematite and hydronium alunite. This transformation is more pronounced at higher A/O ratios, affecting the mineralogical composition of the post-leach solid residue.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106576"},"PeriodicalIF":4.8,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145105653","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":"Palladium adsorption from alkaline glycine-cyanide solutions using activated carbon","authors":"C. Rubina Acuña,&nbsp;E.A. Oraby,&nbsp;G.A. Bezuidenhout,&nbsp;C.C. Beh,&nbsp;J.J. Eksteen","doi":"10.1016/j.hydromet.2025.106575","DOIUrl":"10.1016/j.hydromet.2025.106575","url":null,"abstract":"<div><div>There is an increasing demand for the use of Platinum Group Metals (PGMs) in various industries such as fuel cells, auto catalysts, electrical and electronics, e-waste and medical, which has significantly increased their market value (250 % increased value for palladium). Currently, technologies for separating and purifying metals, such as solvent extraction (SX) and ion exchange (IX), are generally applied with cyanide and acidic chloride systems to recover PGMs. In recent years, applications of amino acids, particularly glycine, have been developed and patented, as an alternative lixiviant for gold and copper leaching. Recent research on e-waste has shown an effective dissolution/leaching of Pd from glycine and glycine-cyanide solutions. The alkaline amino acid leaching represents an opportunity for a more selective and environmentally friendly approach, compared to the current applications using cyanide and chlorine systems.</div><div>The objective of this research is to investigate the feasibility of palladium (Pd) adsorption, using activated carbon, from synthetic leach solutions containing alkaline glycine–cyanide. 24-h tests were performed to assess the impact over Pd adsorption from various operational parameters including Pd initial concentration, pH, glycine and cyanide concentrations, carbon dosage, and temperature. Results showed that Pd can be efficiently recovered from glycine–cyanide solutions using activated carbon under different operational conditions, with the highest recoveries achieved at 20 g/L carbon dosage and pH 9.5 (98.2 %), and 95.5 % at 5000 mg/L glycine. The results have shown that the most significant parameters impacting adsorption efficiency (kinetics) are carbon dosage, temperature and pH. The experimental data from various initial concentrations of Pd were best fitted to the Langmuir model (R² &gt; 0.9), with the maximum uptake capacity (Q_m) at different initial Pd concentrations ranging between 0.5 mg/g and 2.2 mg/g. In addition, the results of the kinetic modelling were best described by a pseudo-second-order model (R² &gt; 0.99), for all parameters studied.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106575"},"PeriodicalIF":4.8,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145118633","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":"Selective adsorption of yttrium(III) and ytterbium(III) from rare earth leachate using a phytic acid (C₆H₁₈O₂₄P₆)-modified adsorbent","authors":"Yaru Duan ,&nbsp;Xingyu Tong ,&nbsp;Yixiang Wang ,&nbsp;Yun Fang ,&nbsp;Jun Wang ,&nbsp;Yang Liu ,&nbsp;Zhenyue Zhang ,&nbsp;Ruan Chi ,&nbsp;Chunqiao Xiao","doi":"10.1016/j.hydromet.2025.106574","DOIUrl":"10.1016/j.hydromet.2025.106574","url":null,"abstract":"<div><div>The adsorption of rare earth ions (RE³⁺) using modified adsorbents has been proven to be an effective and sustainable extraction method. This study screened phytic acid (C₆H₁₈O₂₄P₆) modified <em>Serratia marcescens</em> (SR-PA) for its ability to efficiently adsorb RE³⁺ from rare earth leachate by determining the best adsorption conditions. Quantum theoretical modeling elucidated the binding mode of phytic acid with RE³⁺. The results showed a maximum adsorption capacity of SR-PA was 103 mg/g. The SR-PA data fitted the Langmuir model and the pseudo-first-order kinetic model. The adsorptive capacity of yttrium(III) and ytterbium(III) by SR-PA were 92.9 % and 89.0 %, respectively, and SR-PA significantly increased the distribution coefficient values of yttrium(III) and ytterbium(III). The separation factor calculations revealed that ytterbium(III) was the easiest RE³⁺ to separate, followed by yttrium(III), dysprosium(III), and gadolinium(III). The electrostatic attraction of SR-PA with RE³⁺ was evaluated using zeta potential measurements, and the dual mesopore–macropore structure of SR-PA was confirmed via characterization analyses. The analyses revealed that the phosphate group in SR-PA adsorbs RE³⁺ through complexation, where PA preferentially forms a colloidal structure with RE³⁺. After five cycles, a slight decline in absorption was observed, confirming the reusability of SR-PA. In addition, the biosafety of SR-PA was confirmed through dissolution tests. The structure of SR-PA is stable, and its application prospects are promising.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106574"},"PeriodicalIF":4.8,"publicationDate":"2025-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045783","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":"Aluminium recovery from coal fly ash for the production of high purity alumina","authors":"Cameron J. Johnston ,&nbsp;Rachel A. Pepper ,&nbsp;Wayde N. Martens ,&nbsp;Sara J. Couperthwaite","doi":"10.1016/j.hydromet.2025.106573","DOIUrl":"10.1016/j.hydromet.2025.106573","url":null,"abstract":"<div><div>The vast scale of coal combustion worldwide has led to large amounts of fly ash (waste product) being produced. One method of dealing with this waste is using it as a feedstock for new processes, such as producing high purity alumina (HPA: &gt;99.99 % Al₂O₃). The research presented demonstrates a method of recovering aluminium from coal fly ash for the synthesis of high purity alumina. The method involves: (1) a caustic fusion method that converts mullite into soluble sodalite phase, (2) a pH adjustment to concentrate aluminium, (3) a purification stage using hydrochloric acid crystallisation, and (4) calcination at 1250 °C to convert aluminium chloride hexahydrate crystals to α-Al₂O₃. This method produced HPA with an alumina purity of 99.99 %.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106573"},"PeriodicalIF":4.8,"publicationDate":"2025-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145026480","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 nickel, copper and zinc sulfate solutions from electroplating sludge leachate using a novel synergistic solvent system of DMPY and Versatic 10","authors":"Haokai Peng ,&nbsp;Zuoying Cao ,&nbsp;Shengxi Wu ,&nbsp;Qinggang Li ,&nbsp;Mingyu Wang ,&nbsp;Xinsheng Wu ,&nbsp;Wenjuan Guan ,&nbsp;Guiqing Zhang","doi":"10.1016/j.hydromet.2025.106567","DOIUrl":"10.1016/j.hydromet.2025.106567","url":null,"abstract":"<div><div>As the demand for Ni continues to rise, the recovery of Ni from electroplating sludge leachate has become an effective approach to alleviate supply constraints. However, the presence of impurities such as Cu, Zn, and Ca in the leachate complicates the Ni recovery process. To address these challenges, a novel pyridine group extractant, 2-((dodecylthio) methyl) pyridine (DMPY), was designed, synthesized, and evaluated for its synergistic performance with Versatic 10 (C₁₀H₂₀O₂) in selectively extracting Ni. Under optimal conditions, Ni was selectively recovered from electroplating sludge leachate including Cu, Zn, and Ca through three steps of the extraction processes. Mechanistic studies revealed that both DMPY and Versatic 10 anion coordinated with Ni²⁺, providing charge balance, forming the complex [Ni²⁺(DMPY)₂(C₁₀H₁₉O₂⁻)₂]. This synergistic solvent system significantly improved Ni extraction efficiency while minimizing reagent consumption. In conclusion, The DMPY-Versatic 10 system offers a sustainable and environmentally friendly solution, enhancing the hydrometallurgical treatment of polymetallic electroplating sludge and contributing to resource recovery and environmental protection.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106567"},"PeriodicalIF":4.8,"publicationDate":"2025-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019906","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":"Synchronized removal of non-rare earth ions (Al3+, Fe3+, Th4+, U6+, and F−) from rare earth leach solutions using lanthanum‑cerium oxides for pH adjustment","authors":"Di Wu ,&nbsp;Xinjin Xiao ,&nbsp;An Guo ,&nbsp;Qiaofa Lan ,&nbsp;Huijuan Wang ,&nbsp;Liusheng Ge ,&nbsp;Xiaoqiang Wen ,&nbsp;Lingdong Sun ,&nbsp;Chunsheng Liao","doi":"10.1016/j.hydromet.2025.106572","DOIUrl":"10.1016/j.hydromet.2025.106572","url":null,"abstract":"<div><div>Eliminating non-rare earth anions and cations is a challenge for Chinese rare earth producers due to the increase in the contamination with non-rare earth impurities in leach solutions. Based on the decontamination mechanism of conventional alkaline reagents, a procedure for the synchronized removal of non-rare earth anions and cations from rare earth leach solutions was developed. In this work, the principal non-rare earth anions and cations in the solution (initial pH of 1.12) was decontaminated by adding lanthanum–cerium oxides to adjust the pH to 4.0 with the addition of a 20 g/100 mL aluminum-based carrier at a water bath temperature of 30 °C. The lanthanum‑cerium oxides were mixed at a lanthanum‑cerium molar ratio of 4:1 and roasted at 1000 °C. The removal efficiencies of Al³⁺, Fe³⁺, Th⁴⁺, U⁶⁺, and F⁻ were 97.5 %, 92.7 %, 91.7 %, 97.4 %, and 95.7 %, respectively. The solid produced after decontamination could be transformed into a new aluminum-based carrier for repeated use after washing, drying, and roasting. The variation in non-rare earth anion and cation removal efficiencies was less than 3 % after three cycles. The removal of non-rare earth impurities was significantly improved, with a decrease in the loss of rare earths from 5 % to approximately 2 %. This process opens new application scenarios for highly abundant lanthanum and cerium and avoids the risk of introducing new impurities from conventional alkali sources. This process has practical significance for the green and healthy development of rare earth producing enterprises.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106572"},"PeriodicalIF":4.8,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145019905","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":"Deep eutectic solvents and ionic liquids in hydrometallurgical recovery of metals - A review of recent advances and challenges","authors":"Hafiza Mamoona Khalid,&nbsp;Rafael M. Santos","doi":"10.1016/j.hydromet.2025.106571","DOIUrl":"10.1016/j.hydromet.2025.106571","url":null,"abstract":"<div><div>This review focuses on the hydrometallurgical recovery of metals via deep eutectic solvents (DESs) and ionic liquids (ILs), which are well known for their low toxicity, cost-effectiveness, and eco-friendliness, offering a promising route for sustainable metal extraction through leaching and solvent extraction (SX) processes. The focus is on assessing the efficacy of novel leaching liquids to produce leachates and the use of these unconventional solvents as extractants and diluents in the SX process for metal extraction. This review summarizes and discusses the characteristics of the ILs and DESs used for metal recovery, including their original introduction, synthesis, and classification. The DESs and ILs can be used as lixiviants for metal leaching and have significant potential to replace mineral acids. The selective and efficient leaching of metals from minerals or wastes has been proven in many experimental studies and is surveyed in this review. Solvometallurgy is a new branch of hydrometallurgy that uses DESs and ILs for leaching and SX of metals, and several studies in which both of these solvents are used as mixtures for the recovery and extraction of metals are also included in this review. Furthermore, IL-based and DES-assisted SX processes are discussed in detail, demonstrating that they are a credible alternative to traditional chemical solvents. This review also aims to explore the benefits, challenges, and environmental consequences of using DESs and ILs.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106571"},"PeriodicalIF":4.8,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145045780","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":"Selective leaching and solvent extraction of Lithium from spent batteries","authors":"Emmanuel Ayorinde Ajiboye ,&nbsp;Trevor Dzwiniel","doi":"10.1016/j.hydromet.2025.106566","DOIUrl":"10.1016/j.hydromet.2025.106566","url":null,"abstract":"<div><div>Pre-extracting Li from spent lithium-ion batteries (LIBs) is crucial because the recovery efficiency of Li is low after other critical metals have been extracted. Traditional methods involving black mass roasting followed by water leaching have resulted in the extraction of 76 % Li and 61 % Al. However, pre-leaching Li from pretreated black mass using an oxalic acid solution at both ambient and elevated temperatures significantly improved results, achieving 98.1 % Li, 99.5 % Al, and 100 % Fe extraction while leaving Ni, Co, Mn, and Cu behind under optimal conditions. Oxalic acid crystals were recovered by refrigerating the leach solution at temperatures below 5 °C and were reused with nearly identical leaching efficiency. Selective extraction of Li from the oxalate leach solution was achieved using Cyanex® 936P under optimal conditions. Due to its extremely low Li extraction efficiency, Dichloromethane proved unsuitable as a diluent. Comparative extraction tests using Cyanex® 936P, Cyanex® 272, and DEHPA in kerosene demonstrated that Cyanex® 936P is an excellent extractant for Li, effectively separating it from other impurities. Under optimal conditions, 98.8 % of available Li was extracted using 20 % Cyanex® 936P, compared to 51.1 % with Cyanex® 272 and 39.9 % with DEHPA in kerosene. Additionally, stripping Li from Cyanex® 936P using H₂SO₄ and HCl was explored, with HCl yielding the best performance.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106566"},"PeriodicalIF":4.8,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144989073","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 effect and implication of impurities on the calcination of α spodumene for lithium extraction","authors":"Mark G. Aylmore,&nbsp;Martin A. Wells,&nbsp;Zakaria Quadir,&nbsp;William D.A. Rickard,&nbsp;Kai Rankenburg,&nbsp;Brent I.A. McInnes","doi":"10.1016/j.hydromet.2025.106570","DOIUrl":"10.1016/j.hydromet.2025.106570","url":null,"abstract":"<div><div>A suite of spodumene samples from albite-spodumene type pegmatites, mined for their lithium content, in the Archaean North Pilbara and Yilgarn Cratons regions of Western Australia, were examined to assess the influence of trace element impurities in spodumene and associated gangue phases on the thermal transformation of spodumene. Calcination of spodumene is required to convert the natural, monoclinic α-spodumene form into the tetragonal β-spodumene form, which is more amenable to recovering lithium during hydrometallurgy processing.</div><div>Spodumene contains minor concentrations of Fe (500–10,000 mg/kg), Mn (200–1400 mg/kg) and other trace element impurities incorporated within the crystal structure. Primary gangue mineralogy comprises quartz, Na/K-feldspar and mica, with secondary alteration predominantly as ‘sericitic’ phyllosilicates (muscovite-lepidolite, chlorite/cookeite mixtures) variably enriched in Fe, Mn, Mg and K relative to spodumene.</div><div>Primary and secondary mica undergo thermal dehydroxylation at temperatures (&lt;950 °C) below the spodumene transformation temperature (970–1100 °C). Decomposed micas form melts that coat the surface and partially encapsulate the calcined spodumene grain surfaces. Feldspar decomposition at 1060 to 1200 °C, coincides with spodumene transformation, and can also result in melt formation, depending upon the composition of the feldspars (K-feldspar, albite). The thermal degradation of other mineral contaminants, such as biotite, pyroxene and amphibole from the presence of country rock (mafic, ultramafic) in the concentrate also coincides with the α- to β-spodumene phase transformation. The generated melts that coat grains can reduce the rate of α-β spodumene conversion and the subsequent ability to extract lithium from calcined spodumene.</div><div>Primary Fe and Mn impurities in spodumene, and those hosted by mica impurities within spodumene have a marked effect in decreasing the temperature of the α-γ-β spodumene conversion. Spodumene is not a strong conductor of heat, and the highly exothermic reaction of Fe and Mn oxidation within both mica and spodumene during thermal alteration affects thermal conductivity, leading to increased heat transfer within spodumene particles, which promotes the thermal transformation of spodumene at a lower temperature.</div><div>However, calcined spodumene particles with high Fe and Mn contents (&gt; ∼ 0.5 wt%) showed black, open sintered regions, accompanied by the generation of fine (&lt;5 μm) particles, and exsolution of Fe/Mn-oxides particles. The sintering and the generation of fines in the calciner will lead to reduced lithium recovery from calcined products.</div><div>This study illustrates the importance of minimising micaceous and feldspar components in the concentrate during the beneficiation stage, which can potentially lead to a decrease in lithium recovery during the extraction process. However, the fine-integrated nature of micas associat","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106570"},"PeriodicalIF":4.8,"publicationDate":"2025-08-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988978","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":"Impact of firing temperature and atmosphere on the chemical reactivity of UO2+x powders in nitric acid","authors":"Thomas Barral ,&nbsp;Laurent Claparede ,&nbsp;Nicolas Dacheux","doi":"10.1016/j.hydromet.2025.106569","DOIUrl":"10.1016/j.hydromet.2025.106569","url":null,"abstract":"<div><div>The aim of this work is to study the dissolution kinetics of a series of powdered UO_2+x samples with different structural and microstructural properties. For this purpose, UO_2+x powders were prepared by hydroxide precipitation and then heat-treated at different temperatures under argon and reducing atmospheres. The calcined UO_2+x samples were first investigated <em>ex-situ</em> by several physicochemical techniques in order to highlight the dependence of the normalized dissolution rates on various parameters. The PXRD experiments showed the preservation of the fluorite structure under reducing atmosphere over the whole temperature range studied, while the formation of a U₃O₈ phase was highlighted under argon at <em>T</em> ≤ 1100 °C. The study of the dissolution of UO_2+x samples first highlighted the effect of increasing the calcination temperature (decrease of S_SA), which significantly improves the chemical durability of the solids. The higher the calcination temperature, the lower the reactivity of the sample and the longer the time required to reach full dissolution. Secondly, the presence of a U₃O₈ fraction in some samples calcined under argon resulted in a higher normalized dissolution rate. For comparison, the normalized dissolution rate of a pure U₃O₈ sample reached <em>R</em>_<em>L</em> = (5.6 ± 1.1) × 10⁻¹ g m⁻² d⁻¹, a higher value than that of UO_2+x, <em>R</em>_<em>L</em> = 5.5 × 10⁻² g m⁻² d⁻¹ on average. Furthermore, these samples showed no change in kinetic regime during dissolution, which could be explained by the blocking by U₃O₈ of the transition to a kinetic dissolution regime autocatalyzed by nitrogen species.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106569"},"PeriodicalIF":4.8,"publicationDate":"2025-08-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144925967","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}