Hydrometallurgy最新文献

{"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}

{"title":"Selective indium extraction from zinc oxide dust leachate by microwave-assisted solvent extraction with P507 and stripping with HCl: Thermodynamics and kinetics","authors":"Shiju Li ,&nbsp;Haibei Wang ,&nbsp;Shengdong Wang ,&nbsp;Feng Xie ,&nbsp;Xudong Sun","doi":"10.1016/j.hydromet.2025.106483","DOIUrl":"10.1016/j.hydromet.2025.106483","url":null,"abstract":"<div><div>In this work, indium was extracted from zinc oxide dust leachate using a microwave-assisted P507 extractant, and microwave-assisted indium stripping with hydrochloric acid. The effects of extractant concentration, pH, volume ratio of organic phase to aqueous phase, contact time, temperature and microwave power on indium extraction were investigated. The optimum conditions for indium extraction were obtained as follows: extractant concentration, 25 % (<em>v</em>/v) in sulphonated kerosene; pH = −0.2; O/A (volume ratio of organic phase to aqueous phase) = 1:2; contact time, 2 min; temperature, 40 °C; and microwave power, 70 W. Under these conditions, the extraction efficiencies of indium, zinc, iron and aluminium were 97.6 %, 2.50 %, 0.48 % and 0.89 %, respectively. The separation coefficients of indium for zinc, iron and aluminium were 1333, 7996 and 4442, respectively, which indicated that P507 has good selectivity for indium over zinc, iron and aluminium. The optimum conditions for indium stripping were a hydrochloric acid concentration of 1.5 mol/L, O/A = 2:1, contact time of 3 min, temperature of 40 °C and microwave power of 90 W, under which the indium stripping efficiency was 99.1 %. Additionally, McCabe–Thiele diagrams were constructed for indium extraction by P507 and indium stripping by hydrochloric acid, which theoretically predicted two stages for indium extraction by P507 and only one stage for indium stripping by hydrochloric acid. The advantage of microwave extraction over conventional extraction was that it reduced the time required for the extraction to reach equilibrium. The stoichiometric data for the extraction reactions were determined using the slope method. Thermodynamic studies showed that microwave-assisted indium extraction was feasible, with all negative standard Gibbs free energies, and the introduction of microwaves increased the entropy change of the extraction reaction. Kinetic studies showed that microwave-assisted In(III) extraction followed a pseudo-second-order kinetic model. The mechanism of In(III) extraction involves ion exchange with hydrogen in -P-O-H in P507. The future studies will focus on the amplification of microwave extraction equipment to promote industrialisation.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106483"},"PeriodicalIF":4.8,"publicationDate":"2025-04-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143834300","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":"Direct extraction of lithium from a salt-lake brine of low-chloride and high‑calcium using a TBP-FeCl3 solvent extraction system and stripping with HCl","authors":"Minxiu Zhou ,&nbsp;Hui Su ,&nbsp;Yaoxian Hu ,&nbsp;Wensen Liu ,&nbsp;Zhaowu Zhu ,&nbsp;Tao Qi ,&nbsp;Daoyong Lin","doi":"10.1016/j.hydromet.2025.106487","DOIUrl":"10.1016/j.hydromet.2025.106487","url":null,"abstract":"<div><div>The increasing adoption of lithium-ion batteries in new energy sectors has substantially increased lithium consumption. Chilean salt lakes consist of high concentrations of Li⁺, (1.14 g/L) and Ca²⁺ (&gt;10 g/L) and low concentration of Cl⁻ (&lt;200 g/L). The TBP-FeCl₃ system can efficiently extract lithium from high Mg brine, but the system has not yet been studied in low chloride and high calcium brine. In this paper, the effect of different extraction, scrubbing, and stripping conditions on the lithium extraction percentage from this type of brine was investigated using a TBP-FeCl₃ system. The results indicated that 100 % TBP mixed with brine containing 15–20 g/L Fe³⁺ and 0.05 mol/L HCl at O/A = 1:1, extracted 52.9 % of Li⁺ and produced an organic phase of 0.72 g/L Li⁺, accompanied by Ca²⁺ and Na⁺ concentrations of 2.82 g/L and 2.47 g/L, respectively. The extraction percentage of Li⁺ reached 74.2 % after a four-stage extraction process. The loaded organic phase was scrubbed with 4 mol/L LiCl solution at O/A = 1:1, and the scrubbing percentage of the impurity ions was &gt;90 %. The scrubbed organic phase was stripped by simulated counter-current stripping by 2.5 mol/L HCl at O/A = 15:1 for ten stages, and the recovery of Li⁺ was 80.3 %. The stripping solution had a Li⁺ concentration of 25.3 g/L and an impurity ion concentration of &lt;1 g/L and the loss of Fe³⁺ was &lt;100 mg/L. The TBP-FeCl₃ extraction system offers the efficient and direct extraction of lithium from Chilean brine and provides technical support for the clean mining of lithium resources in South American salt lakes.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106487"},"PeriodicalIF":4.8,"publicationDate":"2025-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850286","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 preliminary study of a sequential leaching process to recover Ag, Au, Cu, and Sn from E-waste","authors":"Dennis Silva Ferreira,&nbsp;Edenir Rodrigues Pereira-Filho","doi":"10.1016/j.hydromet.2025.106476","DOIUrl":"10.1016/j.hydromet.2025.106476","url":null,"abstract":"<div><div>The rapid growth of electronic waste (e-waste) presents both environmental challenges and economic opportunities. This study investigates efficient methods for recovering valuable metals from printed circuit boards (PCBs) using hydrometallurgical processes. The PCB samples from various end-of-life electronic devices were subjected to a series of five leaching stages targeting the leaching of Ag, Au, Cu, and Sn. The first stage using 3 mol/L nitric acid achieved 97 % Cu leaching, reducing Cu content from an average of 20 % (<em>w</em>/w) to 0.74 % (w/w). This stage also affected other metals, leaching 53 % of Ag and 78 % of Sn. Subsequent leaching with thiourea in acidic media containing Fe(NO₃)₃ leached 75 % of Au. An iodine/iodide leach with H₂O₂ as an oxidizer proved highly effective for Ag, with 99 % leaching. This stage also leached an additional 62 % of Au. Two methods for Sn leaching were compared: HCl leaching achieved 98 % efficiency; H₂SO₄ with CuSO₄ also achieved 98 % leaching efficiency. Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) was used to analyze metal concentrations throughout the process. This sequential leaching approach demonstrates the potential for high-efficiency recovery of valuable metals from e-waste, contributing to both economic benefits and environmental sustainability in electronic waste management. The study highlights the complexity of metal interactions with leaching reagents and the importance of optimizing each stage for selective and efficient recovery of metals from e-waste.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106476"},"PeriodicalIF":4.8,"publicationDate":"2025-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143800681","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":"K-jarosite precipitation kinetics at low-moderate temperatures: Factors affecting mechanism, formation rates, solid morphology and crystallinity","authors":"M.S. Buriti,&nbsp;M. Poulain,&nbsp;P. Cézac,&nbsp;L. Casás","doi":"10.1016/j.hydromet.2025.106474","DOIUrl":"10.1016/j.hydromet.2025.106474","url":null,"abstract":"<div><div>Jarosite is a mineral that holds significant importance in the metallurgical industry. For decades, the jarosite process, operating at high temperatures, has been employed to precipitate jarosite and recover Zn. Consequently, many studies have been undertaken to understand the precipitation behavior of jarosite-type compounds. More recently, the development of different hydrometallurgical processes at low temperature led to the need of comprehending the formation of jarosite under such conditions. Therefore, this work investigates the influence of various factors, such as the initial concentration ratio of reactants (K/Fe), agitation, seeding and temperature, on the precipitation rate. Additionally, XRD and SEM analyses of solid products were conducted to assess how those different conditions affect crystallinity and morphology. The experimental results at room temperature demonstrate the existence of three main steps of the precipitation reaction: an instantaneous precipitation, a dissolution and a reprecipitation. Notably, the initial concentration of the reactants and temperature were the main conditions influencing the kinetics of the precipitation and the crystallinity of the solid obtained, while agitation and seeding did not reveal a significant impact. The results and insights obtained from this research are invaluable for improving the understanding of jarosite precipitation at low and moderate temperatures (296 to 343 K) in hydrometallurgical processes.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"235 ","pages":"Article 106474"},"PeriodicalIF":4.8,"publicationDate":"2025-04-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143839711","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":"Microwave-induced modifications in electric arc furnace slag: An attempt to enhance aqueous dissolution","authors":"Recep Kurtulus ,&nbsp;Cansu Kurtulus ,&nbsp;Mahtab Akbarzadeh Khoei ,&nbsp;Marco Cantaluppi ,&nbsp;Juho Yliniemi","doi":"10.1016/j.hydromet.2025.106475","DOIUrl":"10.1016/j.hydromet.2025.106475","url":null,"abstract":"<div><div>Electric arc furnace slag (EAFS) is produced in large amounts during steel manufacturing and can pose ecological hazards when disposed of in nature. Its heterogeneity, intricate mineralogy, and low solubility restrict its applicability in numerous fields, such as cementitious binders, resource recovery, and mineralization. This study investigated three different microwave irradiation techniques—direct (MWD), roasting with NaOH (MWR), and solution (MWS)—to modify the EAFS and exceed the current boundaries. The former involved direct exposure of EAFS (D90: &lt;30 μm) to microwaves, while the latter included a mixed of EAFS and NaOH, followed by microwave roasting. Both microwave-irradiated samples were later dissolved via stirring in aqueous conditions at a 1:100 g/mL ratio. In contrast, MWS comprised dissolution of EAFS in water under microwave irradiation in a closed vessel. The elemental releases were then analyzed using an inductively coupled plasma-optical emission spectrometer. Structural, surface chemistry, and morphology examinations were also conducted. The results indicated that the structural alterations directly influenced release of Al, leading to a dissolution extent of 25 % for MWR, in contrast to the reference, which attained only 10 %. The release of Si was only achieved using MWR, reaching 3 %. The release of Ca was prominent in the MWS, achieving the highest concentration relative to the others and exhibiting 50 % enhancement. The findings obtained by surface and solution chemistry and microstructural images supported the differences in elemental releases among sample series following microwave irradiation. In conclusion, this study demonstrated the promising potential of microwave irradiation to enhance the dissolution of EAFS, providing more insights into its appropriate applications and valuable reuse.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"234 ","pages":"Article 106475"},"PeriodicalIF":4.8,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143776786","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":"Utilization of CO2 as a precipitant to prepare aluminum hydroxide from NaAl(OH)4 solutions: Study on reaction kinetics and mechanism","authors":"Chengqian Zhang ,&nbsp;Youzhi Liu ,&nbsp;Shuwei Guo ,&nbsp;Yuliang Li ,&nbsp;Shufei Wang ,&nbsp;Shangyuan Cheng ,&nbsp;Hongyan Shen","doi":"10.1016/j.hydromet.2025.106473","DOIUrl":"10.1016/j.hydromet.2025.106473","url":null,"abstract":"<div><div>The carbonation reaction of sodium aluminate solution is the most important, green and economical process for preparing aluminum hydroxide and alumina. Controlling carbonation reaction rate and hydroxyl ion concentration (pH) at the reaction endpoint of NaAlO₂ solution is the most critical technical requirement. However, carbonation reaction mechanism is still controversial, and there is no relevant study on the reaction kinetics of hydroxide ion, which affects the control of carbonation reaction and reactor design. This paper reports the study of the change of pH and hydroxide ion concentration in situ, to propose a two-stage carbonation reaction mechanism of NaAlO₂ by comparing with carbonation reaction of NaOH solution. The first stage of reaction mechanism is the neutralization reaction between CO₂ and uncombined NaOH of NaAlO₂ solution. The second stage of reaction mechanism is a sequence of three chemical reactions: (i) NaAlO₂ decomposition generating NaOH, (ii) neutralization between generated NaOH and CO₂, and (iii) hydrolysis of carbonate ions. Secondly, a new experimental method of spontaneous-decomposition reaction of NaAlO₂ solution was innovatively proposed, revealing two first-order decomposition reactions. The reaction rate constant was about 3 × 10⁻³ s⁻¹. Furthermore, the rate equation for hydroxyl ion describing a two-stage carbonation reaction, controlled by mass transfer rate and chemical reaction rate was derived. The correlation coefficients of fitted experimental data were all greater than 0.99. Research found that the decomposition rate constant of carbonation reaction is greater than the spontaneous-decomposition rate constant of NaAlO₂ solution. The decomposition rate of carbonation reaction was affected by the decreasing rate of hydroxide ion concentration. Finally, CO₂ consumption measured by experiment and calculated by kinetics was completely consistent, which verifies the correctness of reaction mechanism and proposed rate equations.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"234 ","pages":"Article 106473"},"PeriodicalIF":4.8,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143747858","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}