Hydrometallurgy最新文献

{"title":"Bioleaching and mechanism of ion-adsorption type rare earth ores and tailings using Acidithiobacillus ferrooxidans","authors":"Chunxiao Zhao ,&nbsp;Baojun Yang ,&nbsp;Shan Hu ,&nbsp;Jun Wang ,&nbsp;Yang Liu ,&nbsp;Guanzhou Qiu","doi":"10.1016/j.hydromet.2025.106495","DOIUrl":"10.1016/j.hydromet.2025.106495","url":null,"abstract":"<div><div>Traditionally, ammonium sulfate (NH₄)₂SO₄ has been utilised as the leaching agent in the extraction of ion-adsorption type rare earth (IATRE) ores. However, this method only extracts rare earth elements (REEs) from the ion-exchangeable phase, leaving behind a substantial amount of tailings that still contain REEs. Therefore, this study explored the bioleaching process of IATRE ores and tailings in the presence of <em>Acidithiobacillus ferrooxidans</em> (<em>A. ferrooxidans</em>) and the reaction mechanism. The results showed that in the two-step bioleaching system, where bacteria were cultured well prior to the addition of minerals for leaching, the extraction efficiencies for La (99.5 %), Ce (78.1 %), Nd (95.8 %), and Y (93.5 %) at a pyrite to IATRE ore mass ratio of 1.5:1 were 23.1 %, 58.3 %, 23.4 %, and 13.8 % higher, respectively, than those obtained using the current (NH₄)₂SO₄ leaching system. X-ray diffraction (XRD), scanning electron microscope coupled with energy-dispersive X-ray spectroscopy (SEM-EDS), and three-dimensional excitation-emission matrix (3DEEM) revealed the bioleaching mechanisms of the IATRE ore. These results demonstrated that the oxidative dissolution of pyrite by <em>A. ferrooxidans</em> promoted the production of acid and Fe²⁺. This facilitated proton exchange reactions between H⁺ and IATRE ores, the acid dissolution of IATRE ores, and the reduction of Ce⁴⁺ in the colloidal sediment phase. Additionally, bacterial surface groups and extracellular polymeric substances (EPS) produced by the bacteria formed complexes with rare earth ions, facilitating the release of REEs from IATRE ores. Furthermore, <em>A. ferrooxidans</em> successfully extracted REEs from IATRE tailings after leaching with (NH₄)₂SO₄. These findings provide valuable insights into the bioleaching of IATRE ores and present a novel approach for the adequate recovery of REEs from IATRE ores and tailings.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"236 ","pages":"Article 106495"},"PeriodicalIF":4.8,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144288874","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 influence of mineralogical characteristics and pH on uranium extraction via in-situ leaching: Preliminary case analysis of the Hadatu uranium deposit, China","authors":"Peng Qiao ,&nbsp;Shengqing Xiong ,&nbsp;Liangquan Ge ,&nbsp;Hao Song ,&nbsp;Huijie Yu ,&nbsp;Yihan Yang ,&nbsp;Ruyi Wang ,&nbsp;Shihu Kang ,&nbsp;Yiru Zhou ,&nbsp;Yuanqing Fan","doi":"10.1016/j.hydromet.2025.106492","DOIUrl":"10.1016/j.hydromet.2025.106492","url":null,"abstract":"<div><div>The mineralogical attributes of uranium ore within sandstone-hosted uranium deposits hold paramount significance in the selection and refinement of in-situ leaching (ISL) of uranium. Nevertheless, the relationship between these mineralogical characteristics and uranium leaching efficiency under varying operational conditions remains an understudied area. Therefore, this study collected uranium ore samples from the Hadatu uranium deposit, China, and carried out optical microscopy (OM), scanning electron microscopy (SEM), X-ray fluorescence spectroscopy (XRF), and carbonate chemical analysis, as well as leaching experiments under different conditions.</div><div>This study found that: (1) The uranium ore from the deposit exhibits relatively high abundances of quartz (60.2 %), feldspar (18.9 %), and total iron (4.56 %), whereas the concentrations of carbonate (0.3 %), CaO (0.7 %), and MgO (0.39 %) are notably low. (2) Uranium mineralization is predominantly composed of pitchblende, which is intimately associated with pyrite, organic matter, and clay minerals. (3) In terms of average leaching efficiency, the ore displays different leaching efficiencies with different reagents at different pH: (i) 74.4 % with H₂SO₄ leaching at pH &lt; 2, (ii) 41.9 % with CO₂ and O₂ leaching at pH 4–5, and (iii) 53.8 % with NH₄HCO₃ and H₂O₂ leaching at pH ∼ 8. Notably, the acid leaching method outperforms the other two methods by a factor of 1.78 and 1.38, respectively.</div><div>The leaching efficiency of uranium is primarily influenced by the mineralogical composition of the ore, the occurrence mode of uranium minerals, and the choice of leaching reagents and pH. Both mineralogical analyses and leaching experiments indicate that the application of an acid ISL process is highly suitable for the exploitation of the Hadatu deposit. This study offers valuable insights for ISL mining in the Hadatu uranium deposit and introduces a new perspective for similar sandstone-hosted uranium deposits with comparable mineralogical attributes.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106492"},"PeriodicalIF":4.8,"publicationDate":"2025-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143912840","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":"Research on the migration of rubidium and mineral phase changes during sulfuric acid leaching of biotite","authors":"Zhengwei Han ,&nbsp;Yinbo Song ,&nbsp;Yu Xie ,&nbsp;Hui Zhong ,&nbsp;Zhiguo He","doi":"10.1016/j.hydromet.2025.106493","DOIUrl":"10.1016/j.hydromet.2025.106493","url":null,"abstract":"<div><div>Acid leaching has been widely employed for the extraction of rubidium (Rb) and lithium (Li) from mica owing to operational simplicity, reduced energy consumption, and enhanced efficiency. However, previous investigations have primarily focused on Li leaching behavior and mechanisms, with limited attention paid to understanding the lattice occupancy of Rb in mica and its influence on the leaching mechanisms. This study examined the effects of various factors on the leaching efficiency and behavior of Rb in sulfuric acid leaching of biotite. The mechanisms of Rb transfer were elucidated through density functional theory (DFT) calculations. Under optimized conditions, Rb leaching efficiency reached 93.8 %. The DFT analyses demonstrated that Rb substitution occurred at potassium sites within biotite (K(Mg,Fe)₃AlSi₃O₁₀(F,OH)₂) layers, with preferential occupation of the six-membered tetrahedral ring centroids. During sulfuric acid leaching of biotite, H⁺ initially penetrates the (001) crystal surface through ion exchange with Rb⁺ and K⁺. It then corrodes the aluminum oxide tetrahedron, resulting in the release of Al³⁺. Ultimately, the octahedral layer undergoes structural disintegration through H⁺ induced cleavage of Fe<img>O bonds, releasing Fe²⁺ species. These findings offer valuable insights and lay the foundation for developing next-generation acid leaching techniques for extracting Rb from Rb-bearing mica.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106493"},"PeriodicalIF":4.8,"publicationDate":"2025-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143918111","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":"Process intensification in precipitation of uranium from post alkali leach liquor using re-dissolution of sodium diuranate slurry: A short review of laboratory and pilot scale test results","authors":"Vipin Kumar Sharma ,&nbsp;P. Sriharsha ,&nbsp;L.K. Rao ,&nbsp;Suman Sarkar ,&nbsp;M.S. Rao","doi":"10.1016/j.hydromet.2025.106491","DOIUrl":"10.1016/j.hydromet.2025.106491","url":null,"abstract":"<div><div>The Uranium Corporation of India Limited (UCIL) Tummalapalle facility processes a low-grade uranium ore (0.042 % U₃O₈), necessitating the enhancement of low uranium concentration (0.74 g/L U₃O₈) in the clarified leach liquor as a critical goal for process optimization in the precipitation stage. Enhanced concentration of U₃O₈ in the process liquor is pivotal for maximizing the recovery of the final uranium product. Various filtration technologies were evaluated at laboratory and pilot scales to recover ultra-fine sodium diuranate (SDU) particles to improve recovery. These technologies included candle filters, ceramic filters, cartridge filters, and ultrafiltration. However, none of these methods proved viable for a sustained operation under plant conditions. Additional techniques such as ion exchange, centrifugation, and nanofiltration were also assessed but failed due to inherent technical constraints. Experimental results from laboratory and pilot scale tests indicated that precipitation at approximately 2.5 g/L U₃O₈ in the leach liquor yielded a product with optimal settling characteristics and minimized uranium losses, both in unprecipitated and precipitated forms. In order to achieve this target and enhance precipitation efficiency, a bleed stream of the sodium diuranate slurry from the precipitation circuit was combined with clarified low grade leach liquor to redissolve SDU and heated to approximately 75–80 °C to prepare a concentrated solution of 2.5 g/L. This approach significantly improved the precipitation efficiency of the process liquor in the low-grade ore processing unit.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106491"},"PeriodicalIF":4.8,"publicationDate":"2025-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143905882","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":"Hydrometallurgical process of spent lithium-ion battery recycling Part. 1 Chemical leaching of valuable metals from cathode active materials: Review and case study","authors":"Chaehyeon Lee ,&nbsp;Dwira Satria Arby ,&nbsp;Chanmin Kim ,&nbsp;Junghyun Lim ,&nbsp;Kyungjung Kwon ,&nbsp;Eunhyea Chung","doi":"10.1016/j.hydromet.2025.106494","DOIUrl":"10.1016/j.hydromet.2025.106494","url":null,"abstract":"<div><div>The rapid growth in global demand for lithium-ion batteries (LIBs) has led to a corresponding increase in the number of spent LIBs. This situation highlights the importance of recycling these batteries to conserve the environment and preserve the raw materials used in their production. Among the various commercial recycling methods, leaching is widely used in hydrometallurgical flowsheets. Through acid leaching with sulfuric, hydrochloric, nitric, phosphoric, citric, and other organic acids such as oxalic, formic, and malic acids, along with alkaline agents such as ammonia, ammonium carbonate, ammonium sulfate, and sodium hydroxide, valuable metals such as Co, Ni, Mn, and Li are recovered. In the leaching process, factors such as leaching agent concentration, reductants, temperature, time, and solid-to-liquid (S/L) ratio impact leaching efficiency. These parameters are also interrelated, requiring an analysis of their interactions. It has been shown that leaching can dissolve over 90 % of metals, which are the primary components of cathodes. This paper presents a comprehensive review of the leaching parameters and optimal conditions for maximizing efficiency, focusing specifically on chemical leaching through an in-depth analysis of relevant literature, experimental details, and cost considerations in a case study.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106494"},"PeriodicalIF":4.8,"publicationDate":"2025-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143937191","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":"Sustainable treatment of solid titanium-gypsum-waste using acidic titanium-white-wastewater to produce high-value α-hemihydrate gypsum","authors":"Yuru Wang ,&nbsp;Mengqi Xiang ,&nbsp;Jiangmei Yi ,&nbsp;Ye Wang ,&nbsp;Wenxiang Tang ,&nbsp;Yanjun Zhong ,&nbsp;Hua Meng ,&nbsp;Xiaodong Ma ,&nbsp;Zhiyuan Chen","doi":"10.1016/j.hydromet.2025.106489","DOIUrl":"10.1016/j.hydromet.2025.106489","url":null,"abstract":"<div><div>Titanium gypsum is a solid waste produced when titanium dioxide manufacturers use sulfuric acid and neutralize the waste acid with lime. The global production of titanium gypsum waste has reached 10 million tons annually. To address the environmental hazards, this study proposes a cost-effective ($2.39/ton), emission-free method to sustainably produce high-value α-hemihydrate gypsum by consuming large quantities of titanium gypsum. The primary iron impurity in titanium gypsum was separated (&gt; 80 %) using titanium white waste acid, yielding high-value red iron oxide (Fe₂O₃) and green vitriol, i.e., hydrated iron(II) sulfate (FeSO₄·7H₂O). Additionally, the thermodynamic process of in-situ dehydration of titanium gypsum at atmospheric pressure in a chlorine-free salt solution was studied, producing large α-hemihydrate gypsum particles of 20 μm size through hydration-recrystallization. This work enhances resource utilization efficiency, reduces environmental contamination from titanium dioxide waste acid and titanium gypsum, and exemplifies an environmentally responsible process with significant implications for the sustainable development of the titanium dioxide industry.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106489"},"PeriodicalIF":4.8,"publicationDate":"2025-04-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143876963","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":"Study on a functionalized ionic liquid [BIim][Cl3] for efficient dissolution of precious metals (Pd, Pt, Au, Rh)","authors":"Feng Feng,&nbsp;Heda Ding,&nbsp;Jiaying Zhang,&nbsp;Lu Yu,&nbsp;Yuxue Yue,&nbsp;Yanxia Sun,&nbsp;Lingling Guo,&nbsp;Xiaoliang Xu,&nbsp;Chunshan Lu,&nbsp;Qunfeng Zhang,&nbsp;Xiaonian Li","doi":"10.1016/j.hydromet.2025.106490","DOIUrl":"10.1016/j.hydromet.2025.106490","url":null,"abstract":"<div><div>The development of industrial technology has significantly promoted the production and accumulation of spent precious metal-based catalysts. This work describes the synthesis of an ionic liquid – [BIim][Cl₃] and its application as an alternative to toxic and corrosive reagents for precious metal leaching from waste catalysts. The leaching process using [BIim][Cl₃] is proved to be safe and green. It offers a higher stability and higher leaching efficiency compared to other reagents used in previous publications. The ionic liquid [BIim][Cl₃] enabled the efficient leaching of Pd and Au, as well as the extremely stable precious metals Pt, Rh under mild conditions. The highest leaching efficiencies achieved by [BIim][Cl₃] were 99.9 %, 98.5 %, 98.6 % and 90.6 % for Pd, Au, Pt and Rh under the optimal leaching conditions, respectively. In order to reveal the leaching mechanism, XPS, far infrared (FIR), NMR, and EDS were used to demonstrate the importance of imidazolium cations in the leaching process. The leaching pathway was proposed based on the DFT calculation results on transition state energy barrier.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106490"},"PeriodicalIF":4.8,"publicationDate":"2025-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143868300","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 rhenium and molybdenum from autoclave acid-leach liquor of molybdenite concentrate using bifunctional ionic liquid [A336][Cy272] in xylene","authors":"Solmaz Nabardi ,&nbsp;Valeh Aghazadeh ,&nbsp;Mehdi D. Esrafili ,&nbsp;Nayyere Kiyani","doi":"10.1016/j.hydromet.2025.106472","DOIUrl":"10.1016/j.hydromet.2025.106472","url":null,"abstract":"<div><div>Bifunctional ionic liquids (Bif-ILs) are a class of liquids in which both cations and anions actively participate in the extraction process through chemical bonds. These liquids exhibit high selectivity and stability. This study investigated the solvent extraction of molybdenum (Mo) and rhenium (Re) using the Bif-IL [A336][Cy272], diluted in xylene. Various parameters, such as stirring speed, temperature, aqueous-to-organic (A/O) phase volume ratio, contact time, acid concentration and extractant concentration, were examined to determine their effects on the extraction recovery and separation factor of Mo and Re. The highest Re/Mo separation factor (SF_Re/Mo = 114) and the highest percentage of Re extraction (91 %) were achieved from a leach solution containing ∼5.5 g L⁻¹ Mo and 6.6 × 10⁻² g L⁻¹ Re. These results were obtained under optimized conditions: [A336][Cy272] at 2.5 % (<em>v</em>/v) in the organic phase, pH = 0.35, A/O = 1/1, contact time = 10 min, stirring speed = 300 rpm, and temperature = 298 K. The extraction mechanism for Mo and Re was studied using the slope analysis method, which revealed that the process follows an ion-association mechanism. The Re stripping <strong>into the</strong> aqueous phase was efficient when 1 M (NH₄)₂CO₃ <strong>was</strong> applied. The Re stripping efficiency <strong>under the</strong> examined conditions was 99.7 %, while the stripping of Mo and other impurities was negligible.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106472"},"PeriodicalIF":4.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143877054","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":"Highly efficient pretreatment for refractory gold ores using persulfate, catalyst and free radical based advanced oxidation processes to improve cyanidation","authors":"Abdelkhalek Barbouchi ,&nbsp;Salma Ayadi ,&nbsp;Rachid Idouhli ,&nbsp;Mohy-eddine Khadiri ,&nbsp;Abdessalem Abouelfida ,&nbsp;Laila Barfoud ,&nbsp;Hakim Faqir ,&nbsp;Intissar Benzakour ,&nbsp;Jaouad Benzakour","doi":"10.1016/j.hydromet.2025.106488","DOIUrl":"10.1016/j.hydromet.2025.106488","url":null,"abstract":"<div><div>The extraction of gold (Au) from refractory ores poses major challenges due to the inclusion of gold particles in sulfide minerals. In this study, an alternative and highly efficient oxidative pretreatment for refractory gold ores and concentrates was developed using persulfate-based advanced oxidation process. This approach generates strong oxidizing radicals to oxidize sulfide minerals, thereby releasing the enclosed gold. For the studied gold concentrate, the extraction of gold by direct cyanidation reached only a yield of 62.6 %. The refractoriness behavior behind this performance has been examined using diagnostic leaching and mineralogical characterization using automated Scanning Electron Microscope (SEM) coupled with Energy Dispersive X-ray (EDX), and it was attributed to encapsulation of fine particles of gold within sulfide minerals mainly pyrite and arsenopyrite. To oxidize these sulfides by persulfate, four activation modes were examined to generate reactive radicals: ultraviolet (UV) activation, ultrasound (US) activation, thermal (T) activation and Ag⁺ and Fe²⁺ catalysts. The experimental results showed that UV and US methods are more efficient in generating reactive radicals, and the removal efficiency of Fe, As and S as well as the subsequent gold extraction by cyanidation varied in the following order: UV &gt; US &gt; T &gt; Ag⁺ &gt; Fe²⁺. The identification tests via utilization of phenol and nitrobenzene chemical probes revealed that the oxidizing radicals predominant and responsible for the oxidation of pyrite and arsenopyrite are sulfate radicals (<span><math><msubsup><mi>SO</mi><mn>4</mn><mrow><mo>•</mo><mo>−</mo></mrow></msubsup></math></span>) and hydroxyl radicals (OH^•). These radicals are generated more effectively through UV and US activation modes. The US activation resulted in a gold extraction of 86.4 %, while UV activation achieved a slightly higher extraction of 88.1 %. The findings showed also that combining UV with Ag⁺ catalyst, US with heating at 80 °C, and US with heating at 80 °C in the presence of an Ag⁺ catalyst resulted in gold extractions of 91.1 %, 92.2 %, and 93.6 %, respectively. The results led to proposing a possible mechanism for the oxidation of sulfide minerals during the pretreatment process.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106488"},"PeriodicalIF":4.8,"publicationDate":"2025-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839710","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":"Reaction and transformation behaviors of ferric oxides and titanium oxide in diasporic bauxite during an alkaline hydrothermal process","authors":"Muhammad Ibrahim ,&nbsp;Yanjun Ou ,&nbsp;Shuhua Ma ,&nbsp;Xiaohui Wang","doi":"10.1016/j.hydromet.2025.106484","DOIUrl":"10.1016/j.hydromet.2025.106484","url":null,"abstract":"<div><div>Ferric and titanium oxides are the main impurities in low-grade bauxite that significantly affect alumina extraction in the Bayer process. This study aims to investigate the reaction and transformation behavior of ferric and titanium oxides in diasporic bauxite during a mild alkaline hydrothermal process to minimize the inhibitory effects of Fe and Ti impurities on bauxite digestion. Analytical techniques such as X-ray diffraction, X-ray fluorescence, inductively coupled plasma, scanning electron microscopy with energy dispersive X-ray spectroscopy, mineral liberation analysis, and Mössbauer spectroscopy were used to analyze the occurrence states of impurities in the raw bauxite and residue, explain their reaction mechanisms, and understand their transformation under hydrothermal conditions. Starch was used as a reducing agent to transform hematite into magnetite and facilitate the subsequent reaction of magnetite with anatase to minimize adverse effects. Thermodynamic calculations and results from experimental investigations showed that under optimized operating conditions of 180 °C, reaction time of 90 min, alkali concentration of 60 g/L, and a small quantity of starch, significant transformations of iron and titanium occurred. These include transformation of (i) hematite to magnetite (54.8 %) and (ii) anatase to Ti-containing stable phases such as ilmenite (19.7 %), ferrous pseudo brookite (12.7 %), ulvite (12.9 %) iron titanate, and perovskites. After the pretreatment with bauxite, alumina digestion can exceed 90.0 %.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106484"},"PeriodicalIF":4.8,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143844035","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}