Pub Date : 2025-10-21DOI: 10.1016/j.hydromet.2025.106601
Puloma Chakrabarty , Geanna Hovey , Minju Cha , Anya Dickinson-Cove , Gaurav Sant , Erika La Plante , David Jassby
To meet the growing demand for critical metals in low carbon technologies, efficient extraction of nickel (Ni) from ultramafic rocks is essential. We present a sonication-based aqueous hydrometallurgical method that enhances Ni extraction under sub-boiling temperatures (∼20–80 °C) and ambient pressure. Batch dissolution experiments were conducted at 30 °C using sulfuric (H₂SO₄) and hydrochloric acid (HCl) with concentrations, between 0.1 and 2 M, solid-to-liquid ratios between 1:500 to 1:5, and sonication frequencies from 0 to 80 kHz over 1–24 h. Dissolution rates of Mg (lizardite) and Ni (pentlandite) were dependent on the acid concentration and stoichiometry. H2SO4 required fewer moles than HCl for dissolution of an equivalent Ni concentration. Sonication significantly increased reaction kinetics, increasing Ni recovery from 15 to 20 % (without sonication) to 65–70 % under optimal conditions (s: l 1:10, 1 M H₂SO₄, 37–40 kHz, 8 h). This process demonstrates a low-energy, acid-efficient dissolution method reduces processing times and minimizes environmental impact. By integrating acoustic stimulation into conventional leaching methods, this method paves way for scalable CO2-negative technologies for Ni extraction that lead to more sustainable hydrometallurgical processing.
{"title":"Sonication-enhanced aqueous dissolution of nickel from ultramafic rocks under ambient conditions","authors":"Puloma Chakrabarty , Geanna Hovey , Minju Cha , Anya Dickinson-Cove , Gaurav Sant , Erika La Plante , David Jassby","doi":"10.1016/j.hydromet.2025.106601","DOIUrl":"10.1016/j.hydromet.2025.106601","url":null,"abstract":"<div><div>To meet the growing demand for critical metals in low carbon technologies, efficient extraction of nickel (Ni) from ultramafic rocks is essential. We present a sonication-based aqueous hydrometallurgical method that enhances Ni extraction under sub-boiling temperatures (∼20–80 °C) and ambient pressure. Batch dissolution experiments were conducted at 30 °C using sulfuric (H₂SO₄) and hydrochloric acid (HCl) with concentrations, between 0.1 and 2 M, solid-to-liquid ratios between 1:500 to 1:5, and sonication frequencies from 0 to 80 kHz over 1–24 h. Dissolution rates of Mg (lizardite) and Ni (pentlandite) were dependent on the acid concentration and stoichiometry. H<sub>2</sub>SO<sub>4</sub> required fewer moles than HCl for dissolution of an equivalent Ni concentration. Sonication significantly increased reaction kinetics, increasing Ni recovery from 15 to 20 % (without sonication) to 65–70 % under optimal conditions (s: l 1:10, 1 M H₂SO₄, 37–40 kHz, 8 h). This process demonstrates a low-energy, acid-efficient dissolution method reduces processing times and minimizes environmental impact. By integrating acoustic stimulation into conventional leaching methods, this method paves way for scalable CO<sub>2</sub>-negative technologies for Ni extraction that lead to more sustainable hydrometallurgical processing.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106601"},"PeriodicalIF":4.8,"publicationDate":"2025-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360218","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 : 2025-10-19DOI: 10.1016/j.hydromet.2025.106600
Xuting Si, Shuai Wei, Yilin Yang, Yulu Li, Youcai Lu
The increasing demand for lithium resources has promoted significant advancements in lithium extraction and recovery technologies. This study introduces a series of novel aminophosphonic acid extractants with varying branched-chain structures, designed to enhance lithium recovery from spent battery leachates with high sodium interference. These bifunctional extractants, incorporating both phosphonic acid and amino groups, demonstrated notable efficiency and selectivity. Under optimal conditions, a single-stage extraction achieved a lithium extraction efficiency of 70 %, with a lithium‑sodium separation factor of 139. A four-stage countercurrent extraction process further elevated the lithium recovery to 99 %. The extraction mechanism was elucidated through Fourier-transform infrared (FT-IR) spectroscopy and 31P nuclear magnetic resonance (NMR) spectroscopy, complemented by density functional theory (DFT) calculations. This research not only provides a feasible method for lithium extraction from high Na/Li ratio leachates but also offers useful insights for industrial applications, highlighting the potential of bifunctional extractants in sustainable lithium recovery.
{"title":"Novel bifunctional aminophosphonic acid extractants for efficient lithium recovery from spent battery leachates with high sodium interference","authors":"Xuting Si, Shuai Wei, Yilin Yang, Yulu Li, Youcai Lu","doi":"10.1016/j.hydromet.2025.106600","DOIUrl":"10.1016/j.hydromet.2025.106600","url":null,"abstract":"<div><div>The increasing demand for lithium resources has promoted significant advancements in lithium extraction and recovery technologies. This study introduces a series of novel aminophosphonic acid extractants with varying branched-chain structures, designed to enhance lithium recovery from spent battery leachates with high sodium interference. These bifunctional extractants, incorporating both phosphonic acid and amino groups, demonstrated notable efficiency and selectivity. Under optimal conditions, a single-stage extraction achieved a lithium extraction efficiency of 70 %, with a lithium‑sodium separation factor of 139. A four-stage countercurrent extraction process further elevated the lithium recovery to 99 %. The extraction mechanism was elucidated through Fourier-transform infrared (FT-IR) spectroscopy and <sup>31</sup>P nuclear magnetic resonance (NMR) spectroscopy, complemented by density functional theory (DFT) calculations. This research not only provides a feasible method for lithium extraction from high Na/Li ratio leachates but also offers useful insights for industrial applications, highlighting the potential of bifunctional extractants in sustainable lithium recovery.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106600"},"PeriodicalIF":4.8,"publicationDate":"2025-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360216","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 : 2025-10-17DOI: 10.1016/j.hydromet.2025.106597
Sina Shakibania, Lena Sundqvist-Öqvist, Sepideh Javanshir, Jan Rosenkranz
The present study focuses on the selective extraction of potassium from a hydrochloric acid-based feldspar leachate using solvent extraction with crown ethers, CE (dibenzo-18-crown-6 and 12-crown-4). The effects of hydrochloric acid concentration, extractant type, diluent, extractant concentration, and organic-to-aqueous phase ratio on potassium extraction efficiency have been examined. Dibenzo-18-crown-6 diluted in m-cresol was shown to preferentially extract potassium (≈85 %) from highly acidic hydrochloric acid solutions (2 to 6 M), with minimal co-extraction of impurities, such as aluminum and sodium, in a single extraction step. Aluminum, however, was shown to be extracted efficiently (≈99 %) at lower acidities (<0.1 M). The extraction mechanisms were explored using various analyses, such as slope analysis, nuclear magnetic resonance, and scanning electron microscopy showing that dibenzo-18-crown-6 forms a highly stable complex with potassium at 1:1 M ratio, (KCl)(CE), driven by the size compatibility between potassium ions and the crown ether cavity. For aluminum, the extraction mechanism likely involves the formation of a cooperative complex where aluminum ions are associated with the potassium-crown ether complex (AlKCl4)(CE). Increasing the concentration of hydrochloric acid increased potassium ion activity, chloride ion activity, and ionic strength in the solution. These changes would enhance selective potassium extraction over the formation and extraction of the aluminum‑potassium cooperative complex.
{"title":"Solvent extraction using crown ethers: Selective recovery of potassium from synthetic K-feldspar leachate","authors":"Sina Shakibania, Lena Sundqvist-Öqvist, Sepideh Javanshir, Jan Rosenkranz","doi":"10.1016/j.hydromet.2025.106597","DOIUrl":"10.1016/j.hydromet.2025.106597","url":null,"abstract":"<div><div>The present study focuses on the selective extraction of potassium from a hydrochloric acid-based feldspar leachate using solvent extraction with crown ethers, CE (dibenzo-18-crown-6 and 12-crown-4). The effects of hydrochloric acid concentration, extractant type, diluent, extractant concentration, and organic-to-aqueous phase ratio on potassium extraction efficiency have been examined. Dibenzo-18-crown-6 diluted in m-cresol was shown to preferentially extract potassium (≈85 %) from highly acidic hydrochloric acid solutions (2 to 6 M), with minimal co-extraction of impurities, such as aluminum and sodium, in a single extraction step. Aluminum, however, was shown to be extracted efficiently (≈99 %) at lower acidities (<0.1 M). The extraction mechanisms were explored using various analyses, such as slope analysis, nuclear magnetic resonance, and scanning electron microscopy showing that dibenzo-18-crown-6 forms a highly stable complex with potassium at 1:1 M ratio, (KCl)(CE), driven by the size compatibility between potassium ions and the crown ether cavity. For aluminum, the extraction mechanism likely involves the formation of a cooperative complex where aluminum ions are associated with the potassium-crown ether complex (AlKCl<sub>4</sub>)(CE). Increasing the concentration of hydrochloric acid increased potassium ion activity, chloride ion activity, and ionic strength in the solution. These changes would enhance selective potassium extraction over the formation and extraction of the aluminum‑potassium cooperative complex.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106597"},"PeriodicalIF":4.8,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360219","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 : 2025-10-17DOI: 10.1016/j.hydromet.2025.106598
Weida Wang , Ling Zhao , Yanxin Bo , Changxiong Zou , Mingtao Zhu , Wanqi Zhang , Junyan Yang
Rare earth tailings are solid residues generated during the hydrometallurgical processing of rare earth ores. They typically contain radionuclides, especially thorium (Th) and uranium (U). Long-term open-air storage poses environmental risks due to rainfall-induced leaching and wind-driven dispersion. In this study, a solidification/stabilization (S/S) method that combines microbially induced calcium carbonate precipitation (MICP) with magnesium ammonium phosphate (MAP) was developed. The dual-phase CaCO3/MgNH4PO4·6H2O system significantly improves mechanical strength, reduces permeability, and enhances radionuclide immobilization. The S/S effectiveness was quantitatively assessed by permeability, unconfined compressive strength (UCS), and leaching tests, and further supported by microstructural analyses including mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The samples treated with MICP and MAP achieved a minimum permeability of 0.38 × 10−5 cm/s, a maximum UCS of 3.86 MPa, and immobilization efficiencies of 87.7 % for Th and 96.0 % for U. Microstructural observations confirmed that calcite-phase CaCO3 and prismatic MgNH4PO4·6H2O crystals densified the pore structure and weakened pore connectivity. This study provides a practical and sustainable approach for the safe disposal and long-term management of rare earth tailings.
{"title":"Mineralization of rare earth tailings by using microbiome-induced synthesis of calcium carbonate and magnesium ammonium phosphate","authors":"Weida Wang , Ling Zhao , Yanxin Bo , Changxiong Zou , Mingtao Zhu , Wanqi Zhang , Junyan Yang","doi":"10.1016/j.hydromet.2025.106598","DOIUrl":"10.1016/j.hydromet.2025.106598","url":null,"abstract":"<div><div>Rare earth tailings are solid residues generated during the hydrometallurgical processing of rare earth ores. They typically contain radionuclides, especially thorium (Th) and uranium (U). Long-term open-air storage poses environmental risks due to rainfall-induced leaching and wind-driven dispersion. In this study, a solidification/stabilization (S/S) method that combines microbially induced calcium carbonate precipitation (MICP) with magnesium ammonium phosphate (MAP) was developed. The dual-phase CaCO<sub>3</sub>/MgNH<sub>4</sub>PO<sub>4</sub>·6H<sub>2</sub>O system significantly improves mechanical strength, reduces permeability, and enhances radionuclide immobilization. The S/S effectiveness was quantitatively assessed by permeability, unconfined compressive strength (UCS), and leaching tests, and further supported by microstructural analyses including mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The samples treated with MICP and MAP achieved a minimum permeability of 0.38 × 10<sup>−5</sup> cm/s, a maximum UCS of 3.86 MPa, and immobilization efficiencies of 87.7 % for Th and 96.0 % for U. Microstructural observations confirmed that calcite-phase CaCO<sub>3</sub> and prismatic MgNH<sub>4</sub>PO<sub>4</sub>·6H<sub>2</sub>O crystals densified the pore structure and weakened pore connectivity. This study provides a practical and sustainable approach for the safe disposal and long-term management of rare earth tailings.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106598"},"PeriodicalIF":4.8,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360217","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 : 2025-10-17DOI: 10.1016/j.hydromet.2025.106599
Salih Cihangir
This study presents a systematic approach to the design, characterization, and application of non-aqueous green solvents (NAGSs) for the leaching of rare earth carbonate hydrates (RECHs). Four NAGSs based on choline chloride, ethylene glycol, and various carboxylic acids were synthesized and evaluated for their physicochemical and electrochemical properties. Among the evaluated formulations, the choline chloride–ethylene glycol–Na₂EDTA·2H₂O mixture (N1) and the chloride–levulinic acid mixture (N2) were found were found suitable for both traditional and electrochemically assisted leaching due to their optimal viscosity, conductivity, and electrochemical stability. Electrochemical assistance significantly enhanced leaching efficiency, with improvements ranging from 22 % to over 300 % for certain elements compared to conventional methods. Mechanistic investigations revealed that the application of an oxidative potential facilitates the protonation and dissolution of RECHs, likely through the generation of localized acidic environments and the formation of intermediate species. The FTIR analysis confirmed the dissolution of carbonate phases and the formation of rare earth–ligand complexes, particularly in the N1 system, where new bands associated with carboxylate and amine coordination were observed. Importantly, the proposed electrochemically assisted method can be applied to different primary or secondary sources in both aqueous and non-aqueous solutions. The results demonstrate the advantages of combining non-aqueous green solvents with electrochemical assistance as an environmentally benign alternative to conventional acid-based leaching, especially for challenging carbonate forms of rare earth elements. This work provides important guidelines for the development of sustainable hydrometallurgical processes, with future directions including solvent recyclability, selective recovery, and environmental assessment.
{"title":"Electrochemically assisted leaching of rare earth carbonates in non-aqueous green solvents: Solvent design, characterization, and process optimization","authors":"Salih Cihangir","doi":"10.1016/j.hydromet.2025.106599","DOIUrl":"10.1016/j.hydromet.2025.106599","url":null,"abstract":"<div><div>This study presents a systematic approach to the design, characterization, and application of non-aqueous green solvents (NAGSs) for the leaching of rare earth carbonate hydrates (RECHs). Four NAGSs based on choline chloride, ethylene glycol, and various carboxylic acids were synthesized and evaluated for their physicochemical and electrochemical properties. Among the evaluated formulations, the choline chloride–ethylene glycol–Na₂EDTA·2H₂O mixture (N1) and the chloride–levulinic acid mixture (N2) were found were found suitable for both traditional and electrochemically assisted leaching due to their optimal viscosity, conductivity, and electrochemical stability. Electrochemical assistance significantly enhanced leaching efficiency, with improvements ranging from 22 % to over 300 % for certain elements compared to conventional methods. Mechanistic investigations revealed that the application of an oxidative potential facilitates the protonation and dissolution of RECHs, likely through the generation of localized acidic environments and the formation of intermediate species. The FTIR analysis confirmed the dissolution of carbonate phases and the formation of rare earth–ligand complexes, particularly in the N1 system, where new bands associated with carboxylate and amine coordination were observed. Importantly, the proposed electrochemically assisted method can be applied to different primary or secondary sources in both aqueous and non-aqueous solutions. The results demonstrate the advantages of combining non-aqueous green solvents with electrochemical assistance as an environmentally benign alternative to conventional acid-based leaching, especially for challenging carbonate forms of rare earth elements. This work provides important guidelines for the development of sustainable hydrometallurgical processes, with future directions including solvent recyclability, selective recovery, and environmental assessment.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106599"},"PeriodicalIF":4.8,"publicationDate":"2025-10-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145360215","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}
Three secondary amides with different numbers of chlorine atom(s)—N-(2-ethylhexyl)monochloroacetamide (MCAA), N-(2-ethylhexyl)dichloroacetamide (DCAA), and N-(2-ethylhexyl)-2,2,2-trichloroacetamide (TCAA)—were synthesised for Ga(III) extraction. These three amides exhibited a preference for extracting Ga(III) compared to other metals at higher HCl concentrations, with the stoichiometries of Ga(III) extraction using the three reagents investigated via slope analysis. Spectroscopic studies were performed to elucidate the extraction mechanism of GaCl4−. The hydronium ion extraction with (O)=C oxygen atoms of amides did not occur in lower HCl concentration media ([HCl] < 8.46 mol dm−3), indicating that (H)-N hydrogen atom displayed a distinctive interaction with GaCl4−. The DCAA exhibited the highest Ga(III) extraction efficiency among the three secondary amides. The proton nuclear magnetic resonance spectroscopic analysis and density functional theory calculations indicated that the δ+ value of the hydrogen atom in (H)-C-Cl2 of DCAA was enhanced to assist GaCl4− extraction with the (H)-N hydrogen atom. Stable intermolecular hydrogen bonding between (H)-N hydrogen and the partially negatively charged (O)=C oxygen atoms of MCAA inhibited GaCl4− extraction. The complete stripping of Ga(III) from the Ga-loaded MCAA and TCAA was achieved using water, while chelation extraction with DCAA suppressed the efficiency of Ga(III) stripping with water.
{"title":"Specific chelating extraction of gallium(III) with H-N and H-CCl2 hydrogen atoms of dichlorinated secondary amide","authors":"Gehui Pang , Shintaro Morisada , Hidetaka Kawakita , Keisuke Ohto","doi":"10.1016/j.hydromet.2025.106596","DOIUrl":"10.1016/j.hydromet.2025.106596","url":null,"abstract":"<div><div>Three secondary amides with different numbers of chlorine atom(s)—<em>N</em>-(2-ethylhexyl)monochloroacetamide (<strong>MCAA</strong>), <em>N</em>-(2-ethylhexyl)dichloroacetamide (<strong>DCAA</strong>), and <em>N</em>-(2-ethylhexyl)-2,2,2-trichloroacetamide (<strong>TCAA</strong>)—were synthesised for Ga(III) extraction. These three amides exhibited a preference for extracting Ga(III) compared to other metals at higher HCl concentrations, with the stoichiometries of Ga(III) extraction using the three reagents investigated <em>via</em> slope analysis. Spectroscopic studies were performed to elucidate the extraction mechanism of GaCl<sub>4</sub><sup>−</sup>. The hydronium ion extraction with (<strong>O</strong>)=C oxygen atoms of amides did not occur in lower HCl concentration media ([HCl] < 8.46 mol dm<sup>−3</sup>), indicating that (<strong>H</strong>)-N hydrogen atom displayed a distinctive interaction with GaCl<sub>4</sub><sup>−</sup>. The <strong>DCAA</strong> exhibited the highest Ga(III) extraction efficiency among the three secondary amides. The proton nuclear magnetic resonance spectroscopic analysis and density functional theory calculations indicated that the <em>δ</em><sup>+</sup> value of the hydrogen atom in (<strong>H</strong>)-C-Cl<sub>2</sub> of <strong>DCAA</strong> was enhanced to assist GaCl<sub>4</sub><sup>−</sup> extraction with the (<strong>H</strong>)-N hydrogen atom. Stable intermolecular hydrogen bonding between (<strong>H</strong>)-N hydrogen and the partially negatively charged (<strong>O</strong>)=C oxygen atoms of <strong>MCAA</strong> inhibited GaCl<sub>4</sub><sup>−</sup> extraction. The complete stripping of Ga(III) from the Ga-loaded <strong>MCAA</strong> and <strong>TCAA</strong> was achieved using water, while chelation extraction with <strong>DCAA</strong> suppressed the efficiency of Ga(III) stripping with water.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106596"},"PeriodicalIF":4.8,"publicationDate":"2025-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322432","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 : 2025-10-12DOI: 10.1016/j.hydromet.2025.106595
Lei Xu, Wen-mi Chen, Shang Fan, Yan-jun Zhang
Foam generation in Bayer precipitation tanks is a major issue that affects the energy efficiency of precipitation in these tanks. However, the factors contributing to foam generation remain poorly understood. This work investigated the relationship between different crystal growth modifiers (CGMs) and foam generation during the precipitation process. Results indicate that in pure sodium aluminate solution, the addition of CGMs directly affects the foam volume. Furthermore, the foam generation potential (FGP) of CGMs varies significantly. CGM-A and CGM-B exhibited minimal FGPs at concentrations up to 300 mg/L in sodium aluminate solution containing aluminum tri-hydroxide (ATH) solids, resulting in practically no foam. In contrast, CGM-C presented stronger FGP at 100 mg/L, generating 8 mL of foam. The FGP of CGMs increased following high-temperature treatment at 260 °C. The FT-IR, GC–MS, and 1H NMR analyses indicated that the large amounts of unsaturated fatty acids in CGM-C were a major cause of foaming. After high-temperature treatment, numerous alkane molecules were generated in the CGM-C, which served as foam stabilizers. This study provides valuable reference for further improvement of the alumina production capacity.
{"title":"Analyses of foam in Bayer precipitation tanks due to crystal growth modifiers","authors":"Lei Xu, Wen-mi Chen, Shang Fan, Yan-jun Zhang","doi":"10.1016/j.hydromet.2025.106595","DOIUrl":"10.1016/j.hydromet.2025.106595","url":null,"abstract":"<div><div>Foam generation in Bayer precipitation tanks is a major issue that affects the energy efficiency of precipitation in these tanks. However, the factors contributing to foam generation remain poorly understood. This work investigated the relationship between different crystal growth modifiers (CGMs) and foam generation during the precipitation process. Results indicate that in pure sodium aluminate solution, the addition of CGMs directly affects the foam volume. Furthermore, the foam generation potential (FGP) of CGMs varies significantly. CGM-A and CGM-B exhibited minimal FGPs at concentrations up to 300 mg/L in sodium aluminate solution containing aluminum tri-hydroxide (ATH) solids, resulting in practically no foam. In contrast, CGM-C presented stronger FGP at 100 mg/L, generating 8 mL of foam. The FGP of CGMs increased following high-temperature treatment at 260 °C. The FT-IR, GC–MS, and <sup>1</sup>H NMR analyses indicated that the large amounts of unsaturated fatty acids in CGM-C were a major cause of foaming. After high-temperature treatment, numerous alkane molecules were generated in the CGM-C, which served as foam stabilizers. This study provides valuable reference for further improvement of the alumina production capacity.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106595"},"PeriodicalIF":4.8,"publicationDate":"2025-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145322434","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}
Ultrafine, near-spherical gibbsite with a low oil-absorption value hold significant potential for use in advanced flame-retardant fillers, polishing materials and dense alumina-bearing ceramics owing to its regular morphology, high dispersibility and good flowability. In this study, ultrafine equiaxial near-spherical gibbsite with a medium particle size (d50) of 359 nm and an oil-absorption values of 25.0 mL/100 g was precipitated by seeded precipitation from sodium aluminate solution. The mixed seeds, comprising bayerite and gibbsite, were prepared by the addition of NaHCO3, Al2(SO4)3, and H2O2, respectively. A high bayerite content in the NaHCO3-induced seeds, combined with significant supersaturation fluctuations, enabled a precipitation efficiency exceeding 51 % at an initial temperature of 80 °C for 35 h. Preferential growth of the (110), (100), and (001) planes occurred during the early stage, followed by the emergence of the (101) and (112) planes in the mid-to-late stage. High supersaturation from bayerite dissolution and adsorption of Al(OH)4− ions promoted the development of (001), (110), (100), (101), and (112) planes, resulting in the formation of equiaxial near-spherical gibbsite. Furthermore, the low surface energy and high zeta potential of the well-crystallized gibbsite precipitated from NaHCO3-induced seeds contributed to its low oil absorption. These findings indicate that the presence of bayerite in seeds, elevated interfacial supersaturation, and high temperature collectively facilitate the formation of ultrafine, equiaxial, near-spherical gibbsite.
{"title":"Precipitation of the ultrafine equiaxial near-spherical gibbsite with low oil absorption value by adding mixed seeds","authors":"Jinquan Wen, Guihua Liu, Tiangui Qi, Qiusheng Zhou, Zhihong Peng, Xiaobin Li, Yilin Wang, Leiting Shen","doi":"10.1016/j.hydromet.2025.106586","DOIUrl":"10.1016/j.hydromet.2025.106586","url":null,"abstract":"<div><div>Ultrafine, near-spherical gibbsite with a low oil-absorption value hold significant potential for use in advanced flame-retardant fillers, polishing materials and dense alumina-bearing ceramics owing to its regular morphology, high dispersibility and good flowability. In this study, ultrafine equiaxial near-spherical gibbsite with a medium particle size (d<sub>50</sub>) of 359 nm and an oil-absorption values of 25.0 mL/100 g was precipitated by seeded precipitation from sodium aluminate solution. The mixed seeds, comprising bayerite and gibbsite, were prepared by the addition of NaHCO<sub>3</sub>, Al<sub>2</sub>(SO<sub>4</sub>)<sub>3</sub>, and H<sub>2</sub>O<sub>2</sub>, respectively. A high bayerite content in the NaHCO<sub>3</sub>-induced seeds, combined with significant supersaturation fluctuations, enabled a precipitation efficiency exceeding 51 % at an initial temperature of 80 °C for 35 h. Preferential growth of the (110), (100), and (001) planes occurred during the early stage, followed by the emergence of the (101) and (112) planes in the mid-to-late stage. High supersaturation from bayerite dissolution and adsorption of Al(OH)<sub>4</sub><sup>−</sup> ions promoted the development of (001), (110), (100), (101), and (112) planes, resulting in the formation of equiaxial near-spherical gibbsite. Furthermore, the low surface energy and high zeta potential of the well-crystallized gibbsite precipitated from NaHCO<sub>3</sub>-induced seeds contributed to its low oil absorption. These findings indicate that the presence of bayerite in seeds, elevated interfacial supersaturation, and high temperature collectively facilitate the formation of ultrafine, equiaxial, near-spherical gibbsite.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106586"},"PeriodicalIF":4.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145270436","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 : 2025-10-08DOI: 10.1016/j.hydromet.2025.106584
M. Nicol
The role of lead ions in the cyanidation of gold has been extensively studied in this investigation. In addition to a speciation analysis using accepted thermodynamic data, the equilibrium potential for the deposition of lead under cyanidation conditions has been estimated. This has been used in conjunction with other electrochemical measurements to confirm that bulk lead metal is not deposited on a gold surface during cyanidation. The underpotential deposition of lead has been confirmed and it has been shown that an incomplete layer of lead is responsible for the increased rates in the presence of lead. The detrimental effect of high lead concentrations appears to be the result of the formation of a complete lead layer on the gold surface.
A less extensive study of the effect of sulfide ions on the rate of cyanidation has confirmed that low (micro-molar) concentrations of sulfide ions enhance the dissolution of gold in cyanide solutions but inhibit the rate of dissolution at high concentrations. The detrimental effect is associated with the anodic oxidation of gold and the formation of a passivating layer of Au2S is possibly responsible. There does not appear to be a significant effect of sulfide on the kinetics of the cathodic reduction of oxygen. A gold alloy containing 10 % silver is less susceptible to the inhibitory effect of sulfide ions.
{"title":"The cyanidation of gold. III. Mechanistic details of the role of lead and sulfide ions","authors":"M. Nicol","doi":"10.1016/j.hydromet.2025.106584","DOIUrl":"10.1016/j.hydromet.2025.106584","url":null,"abstract":"<div><div>The role of lead ions in the cyanidation of gold has been extensively studied in this investigation. In addition to a speciation analysis using accepted thermodynamic data, the equilibrium potential for the deposition of lead under cyanidation conditions has been estimated. This has been used in conjunction with other electrochemical measurements to confirm that bulk lead metal is not deposited on a gold surface during cyanidation. The underpotential deposition of lead has been confirmed and it has been shown that an incomplete layer of lead is responsible for the increased rates in the presence of lead. The detrimental effect of high lead concentrations appears to be the result of the formation of a complete lead layer on the gold surface.</div><div>A less extensive study of the effect of sulfide ions on the rate of cyanidation has confirmed that low (micro-molar) concentrations of sulfide ions enhance the dissolution of gold in cyanide solutions but inhibit the rate of dissolution at high concentrations. The detrimental effect is associated with the anodic oxidation of gold and the formation of a passivating layer of Au<sub>2</sub>S is possibly responsible. There does not appear to be a significant effect of sulfide on the kinetics of the cathodic reduction of oxygen. A gold alloy containing 10 % silver is less susceptible to the inhibitory effect of sulfide ions.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106584"},"PeriodicalIF":4.8,"publicationDate":"2025-10-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145271037","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 : 2025-10-04DOI: 10.1016/j.hydromet.2025.106585
Benjamin Schroeder , Michael Free , Prashant K. Sarswat
The unique optical, electronic, and magnetic properties of the Rare Earth Elements (La-Lu + Sc, Y) have led to a significant increase in their demand by a wide variety of industries. This, coupled with the significant difficulty associated with their extraction, separation, and purification, has resulted in a strong interest in replacing the traditional solvent extraction with a new approach. In response, a new technology called “Field-Effect Separation” (FES) has been developed, which utilizes differences in the magnetic susceptibilities of ions in a strong field to separate them from one another. While it has been demonstrated that this approach can work, it is necessary to more fully understand and optimize the separation of elements. The approach taken to study this was to suspend a solution of REE ions in a firm gelatin, separating them using a strong magnet, freezing the sample to preserve separation, and taking fine slices to analyze the concentration of ions at different spatial positions relative to the magnet as well as different times relative to the beginning of the magnetic field exposure. The results show a significant concentration effect for the magnetically susceptible REEs near the magnet's surface, while the non-susceptible ions seem relatively unconcentrated by the magnetic field. Additionally, among the susceptible REEs, at certain, short separation timescales, a significant stratification of REEs was observed. This suggests that the REEs can be separated from one another using FES assuming a correct time and length scale can be selected for the system.
{"title":"Field-effect separation of rare earth elements in gelatin-supported media","authors":"Benjamin Schroeder , Michael Free , Prashant K. Sarswat","doi":"10.1016/j.hydromet.2025.106585","DOIUrl":"10.1016/j.hydromet.2025.106585","url":null,"abstract":"<div><div>The unique optical, electronic, and magnetic properties of the Rare Earth Elements (La-Lu + Sc, Y) have led to a significant increase in their demand by a wide variety of industries. This, coupled with the significant difficulty associated with their extraction, separation, and purification, has resulted in a strong interest in replacing the traditional solvent extraction with a new approach. In response, a new technology called “Field-Effect Separation” (FES) has been developed, which utilizes differences in the magnetic susceptibilities of ions in a strong field to separate them from one another. While it has been demonstrated that this approach can work, it is necessary to more fully understand and optimize the separation of elements. The approach taken to study this was to suspend a solution of REE ions in a firm gelatin, separating them using a strong magnet, freezing the sample to preserve separation, and taking fine slices to analyze the concentration of ions at different spatial positions relative to the magnet as well as different times relative to the beginning of the magnetic field exposure. The results show a significant concentration effect for the magnetically susceptible REEs near the magnet's surface, while the non-susceptible ions seem relatively unconcentrated by the magnetic field. Additionally, among the susceptible REEs, at certain, short separation timescales, a significant stratification of REEs was observed. This suggests that the REEs can be separated from one another using FES assuming a correct time and length scale can be selected for the system.</div></div>","PeriodicalId":13193,"journal":{"name":"Hydrometallurgy","volume":"239 ","pages":"Article 106585"},"PeriodicalIF":4.8,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145270451","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}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号