Pub Date : 2025-12-01Epub Date: 2025-09-05DOI: 10.1016/j.hydromet.2025.106567
Haokai Peng , Zuoying Cao , Shengxi Wu , Qinggang Li , Mingyu Wang , Xinsheng Wu , Wenjuan Guan , Guiqing Zhang
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.
{"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 , Zuoying Cao , Shengxi Wu , Qinggang Li , Mingyu Wang , Xinsheng Wu , Wenjuan Guan , 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 (C<sub>10</sub>H<sub>20</sub>O<sub>2</sub>) 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 Ni<sup>2+</sup>, providing charge balance, forming the complex [Ni<sup>2+</sup>(DMPY)<sub>2</sub>(C₁₀H<sub>19</sub>O₂<sup>−</sup>)<sub>2</sub>]. 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":"2025-12-01","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}
Pub Date : 2025-12-01Epub Date: 2025-09-13DOI: 10.1016/j.hydromet.2025.106575
C. Rubina Acuña, E.A. Oraby, G.A. Bezuidenhout, C.C. Beh, J.J. Eksteen
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.
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 > 0.9), with the maximum uptake capacity (Qm) 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 > 0.99), for all parameters studied.
{"title":"Palladium adsorption from alkaline glycine-cyanide solutions using activated carbon","authors":"C. Rubina Acuña, E.A. Oraby, G.A. Bezuidenhout, C.C. Beh, 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 (R<sup>2</sup> > 0.9), with the maximum uptake capacity (Q<sub>m</sub>) 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 (R<sup>2</sup> > 0.99), for all parameters studied.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106575"},"PeriodicalIF":4.8,"publicationDate":"2025-12-01","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}
Pub Date : 2025-12-01Epub Date: 2025-09-27DOI: 10.1016/j.hydromet.2025.106578
Yanzhu Liu , Fen Nie , Lihui Liu , Yanrong Ding , Ying Ma , Zhengxiong Ding , Qing Zhao , Yongxiu Li
The separation of aluminum from rare earths (REs) by precipitation using pH adjustments with ammonium bicarbonate (ABC) is not satisfactory because of their co-precipitation, which affects the crystallization and the purity of rare earth carbonate. Therefore, it is extremely challenging to obtain high recovery of REs with high purity due to loss of REs during precipitation. This paper proposes a precipitation method using ABC in the presence of triammonium citrate (TAC) to separate aluminum from lanthanum and cerium. The results show that the removal efficiency of iron and aluminum and the loss of REs due to coprecipitation (%) depend on the dosage of TAC and ABC and the solution pH. A complementary relationship exists between the removal efficiency of aluminum and the loss of REs during precipitation. The optimal dosage of TAC is linear with the concentration of aluminum or the molar ratio of aluminum to iron. It was found that the removal efficiency of iron, aluminum and the loss of REs during precipitation are 100 %, 93 % and 5.6 %, respectively, for an iron‑aluminum ratio of 0.05, and the optimal dosage of TAC is 4–5 % of the aluminum content. After removing the aluminum and iron, the calcined RE2O3 product with purity of 99.6 % and aluminum content of 0.31 % was obtained. Compared with the products without purification or purification without the addition of TAC, the purity of RE2O3 product increased by 9.31 % and 1.39 %, and the aluminum content decreased by 1.99 % and 0.78 % respectively. The addition of TAC can promote the precipitation of aluminum at lower pH through its coordination with iron and aluminum, while reducing the loss of REs during precipitation and decreasing the effect of iron on the removal efficiency aluminum.
{"title":"Efficient separation of Al and Fe impurities from La-Ce chloride solution by pH adjustments with ammonium bicarbonate in the presence of triammonium citrate","authors":"Yanzhu Liu , Fen Nie , Lihui Liu , Yanrong Ding , Ying Ma , Zhengxiong Ding , Qing Zhao , Yongxiu Li","doi":"10.1016/j.hydromet.2025.106578","DOIUrl":"10.1016/j.hydromet.2025.106578","url":null,"abstract":"<div><div>The separation of aluminum from rare earths (REs) by precipitation using pH adjustments with ammonium bicarbonate (ABC) is not satisfactory because of their co-precipitation, which affects the crystallization and the purity of rare earth carbonate. Therefore, it is extremely challenging to obtain high recovery of REs with high purity due to loss of REs during precipitation. This paper proposes a precipitation method using ABC in the presence of triammonium citrate (TAC) to separate aluminum from lanthanum and cerium. The results show that the removal efficiency of iron and aluminum and the loss of REs due to coprecipitation (%) depend on the dosage of TAC and ABC and the solution pH. A complementary relationship exists between the removal efficiency of aluminum and the loss of REs during precipitation. The optimal dosage of TAC is linear with the concentration of aluminum or the molar ratio of aluminum to iron. It was found that the removal efficiency of iron, aluminum and the loss of REs during precipitation are 100 %, 93 % and 5.6 %, respectively, for an iron‑aluminum ratio of 0.05, and the optimal dosage of TAC is 4–5 % of the aluminum content. After removing the aluminum and iron, the calcined RE<sub>2</sub>O<sub>3</sub> product with purity of 99.6 % and aluminum content of 0.31 % was obtained. Compared with the products without purification or purification without the addition of TAC, the purity of RE<sub>2</sub>O<sub>3</sub> product increased by 9.31 % and 1.39 %, and the aluminum content decreased by 1.99 % and 0.78 % respectively. The addition of TAC can promote the precipitation of aluminum at lower pH through its coordination with iron and aluminum, while reducing the loss of REs during precipitation and decreasing the effect of iron on the removal efficiency aluminum.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106578"},"PeriodicalIF":4.8,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216584","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}
Pub Date : 2025-12-01Epub Date: 2025-09-04DOI: 10.1016/j.hydromet.2025.106572
Di Wu , Xinjin Xiao , An Guo , Qiaofa Lan , Huijuan Wang , Liusheng Ge , Xiaoqiang Wen , Lingdong Sun , Chunsheng Liao
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.
{"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 , Xinjin Xiao , An Guo , Qiaofa Lan , Huijuan Wang , Liusheng Ge , Xiaoqiang Wen , Lingdong Sun , 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 Al<sup>3+</sup>, Fe<sup>3+</sup>, Th<sup>4+</sup>, U<sup>6+</sup>, and F<sup>−</sup> 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":"2025-12-01","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}
Pub Date : 2025-12-01Epub Date: 2025-09-27DOI: 10.1016/j.hydromet.2025.106579
M. Nicol
Despite the fact that the cyanidation process for the recovery of gold was patented almost 140 years ago, understanding of the dissolution of gold has proved to be particularly elusive. While it is widely accepted to be a typical electrochemically-based corrosion process, details of the published kinetics of the anodic and cathodic reactions have been found to be very variable with little agreement between many studies, predominantly of the anodic reaction.
In this series of three papers, an attempt has been made to shed some light on the electrochemistry of gold in cyanide solutions. Unlike many previous studies, the use of gold‑silver alloys and an electrode fabricated using gold from an actual plant have been used in addition to pure gold. Solutions from two gold plants have also been compared to pure solutions.
The first of these papers summarizes and compares the literature on the anodic characteristics of gold dissolution in cyanide solutions. The use of the mixed-potential model to describe the kinetics of gold dissolution and the important measurement of mixed potentials under typical cyanidation conditions are described in detail with an emphasis on the possible passivation of gold and the effect of the metal and solution composition on the passivation process.
A number of small scale dissolution experiments using various gold materials and solutions has been undertaken in conjunction with mixed potential and anodic voltammetric measurements. This study has shown that electrochemical studies using pure gold electrodes in pure solutions cannot be used to predict the reactivity of gold under actual plant conditions.
{"title":"The cyanidation of gold. 1. Mixed potential and dissolution studies","authors":"M. Nicol","doi":"10.1016/j.hydromet.2025.106579","DOIUrl":"10.1016/j.hydromet.2025.106579","url":null,"abstract":"<div><div>Despite the fact that the cyanidation process for the recovery of gold was patented almost 140 years ago, understanding of the dissolution of gold has proved to be particularly elusive. While it is widely accepted to be a typical electrochemically-based corrosion process, details of the published kinetics of the anodic and cathodic reactions have been found to be very variable with little agreement between many studies, predominantly of the anodic reaction.</div><div>In this series of three papers, an attempt has been made to shed some light on the electrochemistry of gold in cyanide solutions. Unlike many previous studies, the use of gold‑silver alloys and an electrode fabricated using gold from an actual plant have been used in addition to pure gold. Solutions from two gold plants have also been compared to pure solutions.</div><div>The first of these papers summarizes and compares the literature on the anodic characteristics of gold dissolution in cyanide solutions. The use of the mixed-potential model to describe the kinetics of gold dissolution and the important measurement of mixed potentials under typical cyanidation conditions are described in detail with an emphasis on the possible passivation of gold and the effect of the metal and solution composition on the passivation process.</div><div>A number of small scale dissolution experiments using various gold materials and solutions has been undertaken in conjunction with mixed potential and anodic voltammetric measurements. This study has shown that electrochemical studies using pure gold electrodes in pure solutions cannot be used to predict the reactivity of gold under actual plant conditions.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106579"},"PeriodicalIF":4.8,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216647","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}
Pub Date : 2025-12-01Epub Date: 2025-09-02DOI: 10.1016/j.hydromet.2025.106571
Hafiza Mamoona Khalid, Rafael M. Santos
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.
{"title":"Deep eutectic solvents and ionic liquids in hydrometallurgical recovery of metals - A review of recent advances and challenges","authors":"Hafiza Mamoona Khalid, 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":"2025-12-01","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}
Pub Date : 2025-12-01Epub Date: 2025-09-11DOI: 10.1016/j.hydromet.2025.106574
Yaru Duan , Xingyu Tong , Yixiang Wang , Yun Fang , Jun Wang , Yang Liu , Zhenyue Zhang , Ruan Chi , Chunqiao Xiao
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 Serratia marcescens (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.
{"title":"Selective adsorption of yttrium(III) and ytterbium(III) from rare earth leachate using a phytic acid (C₆H₁₈O₂₄P₆)-modified adsorbent","authors":"Yaru Duan , Xingyu Tong , Yixiang Wang , Yun Fang , Jun Wang , Yang Liu , Zhenyue Zhang , Ruan Chi , 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 (RE<sup>3+</sup>) 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 RE<sup>3+</sup> from rare earth leachate by determining the best adsorption conditions. Quantum theoretical modeling elucidated the binding mode of phytic acid with RE<sup>3+</sup>. 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 RE<sup>3+</sup> to separate, followed by yttrium(III), dysprosium(III), and gadolinium(III). The electrostatic attraction of SR-PA with RE<sup>3+</sup> 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 RE<sup>3+</sup> through complexation, where PA preferentially forms a colloidal structure with RE<sup>3+</sup>. 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":"2025-12-01","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}
Pub Date : 2025-12-01Epub Date: 2025-09-01DOI: 10.1016/j.hydromet.2025.106566
Emmanuel Ayorinde Ajiboye , Trevor Dzwiniel
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.
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Pub Date : 2025-12-01Epub Date: 2025-09-30DOI: 10.1016/j.hydromet.2025.106580
M. Nicol
An extensive study has been undertaken of the reduction of oxygen on various gold electrodes under conditions appropriate to the cyanide leaching of gold. Voltammetric studies with various gold electrodes and ring-disk electrode measurements with pure gold have demonstrated that the 2-step reduction involving peroxide as an intermediate is complex with variable extents of production of peroxide and reduction to water depending on the electrode material and solution purity. There is thus no simple stoichiometry for the reduction of oxygen although the use of a 2-electron reduction is probably the best approximation under plant conditions. This is contrary to the often accepted 4-electron process.
The nature of the gold surface is important with lower reactivity of gold‑silver alloy and plant electrodes relative to pure gold. The sensitivity of oxygen to the presence of underpotentially deposited lead has been demonstrated in solutions contaminated with lead ions. Lead ions have a significant catalytic effect on the kinetics of oxygen reduction that can be attributed to the known effect of underpotentially deposited lead on the reduction of oxygen on gold electrodes in acidic and highly alkaline solutions. Thus, both the anodic dissolution of gold and the cathodic reduction of oxygen are catalysed in the presence of low concentrations of lead ions.
{"title":"The cyanidation of gold. II. The cathodic reduction of oxygen","authors":"M. Nicol","doi":"10.1016/j.hydromet.2025.106580","DOIUrl":"10.1016/j.hydromet.2025.106580","url":null,"abstract":"<div><div>An extensive study has been undertaken of the reduction of oxygen on various gold electrodes under conditions appropriate to the cyanide leaching of gold. Voltammetric studies with various gold electrodes and ring-disk electrode measurements with pure gold have demonstrated that the 2-step reduction involving peroxide as an intermediate is complex with variable extents of production of peroxide and reduction to water depending on the electrode material and solution purity. There is thus no simple stoichiometry for the reduction of oxygen although the use of a 2-electron reduction is probably the best approximation under plant conditions. This is contrary to the often accepted 4-electron process.</div><div>The nature of the gold surface is important with lower reactivity of gold‑silver alloy and plant electrodes relative to pure gold. The sensitivity of oxygen to the presence of underpotentially deposited lead has been demonstrated in solutions contaminated with lead ions. Lead ions have a significant catalytic effect on the kinetics of oxygen reduction that can be attributed to the known effect of underpotentially deposited lead on the reduction of oxygen on gold electrodes in acidic and highly alkaline solutions. Thus, both the anodic dissolution of gold and the cathodic reduction of oxygen are catalysed in the presence of low concentrations of lead ions.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106580"},"PeriodicalIF":4.8,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145216585","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}
Pub Date : 2025-12-01Epub Date: 2025-08-23DOI: 10.1016/j.hydromet.2025.106556
Luis Beiza , Jochen Petersen , Lilian Velásquez-Yévenes
The dissolution of chalcopyrite (CuFeS2) in a heap leaching environment is known to progress slowly; this is mainly attributed to the formation of a product layer that inhibits the dissolution of copper from the mineral. Transporting the dissolved ions from the inner regions of the larger particles to the bulk solution through cracks and/or pores might also slow the process. Therefore, a systematic long-term study has been undertaken to determine the presence and propagation of pores, fissures or crack networks in 12–17 mm particles of a sulfide ore containing mainly quartz (SiO2), chalcopyrite and pyrite (FeS2) during its dissolution under chloride-rich heap leaching conditions. Each particle was placed in a cylindrical receptacle and flooded with 0.1 mol/L H2SO4 solutions at 0, 20 and 150 g/L of chloride (as NaCl) using 0, 0.5 and 1 g/L initial cupric ion as the oxidant and leached for a period of up to 180 days at room temperature (18–22 °C). The generation of cracks and fissures and dissolution of mineral phases were observed using X-ray Computed Tomography (X-CT) at regular intervals during leaching. Additional experiments were run using 150 g/L Cl− to evaluate acidity from pH -0.4 (1.0 mol/L H2SO4) up to pH 3, as well as the effect of temperature at room temperature and 50 °C.
The results indicated that copper dissolution increased with increasing chloride concentration at room temperature and that the initial presence of cupric ions somewhat enhances the extraction. It was found that between pH 1 and 0.2 (0.1 mol/L H2SO4) at 150 g/L Cl− the dissolution is enhanced but inhibited at higher acid concentration. Low acidity (pH 3) promotes the precipitation of Fe that can block the pores and inhibit the dissolution of chalcopyrite. The X-CT scans confirmed that the gradual evolution of fissures and network of cracks over time enhanced the solution contact with the value mineral inside the particles, which then gradually disintegrated. In line with the leaching results, this effect seemed to be intensified at the higher chloride concentrations and when increasing temperature from 20 to 50 °C. The homogenous dissolution of chalcopyrite grains throughout the particle hints at the presence of galvanic coupling with pyrite grains as the key mode of chalcopyrite dissolution.
{"title":"X-ray tomography study on the leaching dynamics of, and pore evolution in, large chalcopyrite ore particles during chloride leaching","authors":"Luis Beiza , Jochen Petersen , Lilian Velásquez-Yévenes","doi":"10.1016/j.hydromet.2025.106556","DOIUrl":"10.1016/j.hydromet.2025.106556","url":null,"abstract":"<div><div>The dissolution of chalcopyrite (CuFeS<sub>2</sub>) in a heap leaching environment is known to progress slowly; this is mainly attributed to the formation of a product layer that inhibits the dissolution of copper from the mineral. Transporting the dissolved ions from the inner regions of the larger particles to the bulk solution through cracks and/or pores might also slow the process. Therefore, a systematic long-term study has been undertaken to determine the presence and propagation of pores, fissures or crack networks in 12–17 mm particles of a sulfide ore containing mainly quartz (SiO<sub>2</sub>), chalcopyrite and pyrite (FeS<sub>2</sub>) during its dissolution under chloride-rich heap leaching conditions. Each particle was placed in a cylindrical receptacle and flooded with 0.1 mol/L H<sub>2</sub>SO<sub>4</sub> solutions at 0, 20 and 150 g/L of chloride (as NaCl) using 0, 0.5 and 1 g/L initial cupric ion as the oxidant and leached for a period of up to 180 days at room temperature (18–22 °C). The generation of cracks and fissures and dissolution of mineral phases were observed using X-ray Computed Tomography (X-CT) at regular intervals during leaching. Additional experiments were run using 150 g/L Cl<sup>−</sup> to evaluate acidity from pH -0.4 (1.0 mol/L H<sub>2</sub>SO<sub>4</sub>) up to pH 3, as well as the effect of temperature at room temperature and 50 °C.</div><div>The results indicated that copper dissolution increased with increasing chloride concentration at room temperature and that the initial presence of cupric ions somewhat enhances the extraction. It was found that between pH 1 and 0.2 (0.1 mol/L H<sub>2</sub>SO<sub>4</sub>) at 150 g/L Cl<sup>−</sup> the dissolution is enhanced but inhibited at higher acid concentration. Low acidity (pH 3) promotes the precipitation of Fe that can block the pores and inhibit the dissolution of chalcopyrite. The X-CT scans confirmed that the gradual evolution of fissures and network of cracks over time enhanced the solution contact with the value mineral inside the particles, which then gradually disintegrated. In line with the leaching results, this effect seemed to be intensified at the higher chloride concentrations and when increasing temperature from 20 to 50 °C. The homogenous dissolution of chalcopyrite grains throughout the particle hints at the presence of galvanic coupling with pyrite grains as the key mode of chalcopyrite dissolution.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"238 ","pages":"Article 106556"},"PeriodicalIF":4.8,"publicationDate":"2025-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144895839","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}
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