Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have ...Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have been applied for the remediation of chromiumcontaminated soils,with varying degrees of success depending on soil type and contaminant form.However,the removal rate of total chromium(Cr)and hexavalent chromium(Cr(Ⅵ))often fluctuates based on the chemical composition of the leaching agents,as well as the soil’s physicochemical properties,such as pH and Cr speciation stability.Therefore,this study investigates the effectiveness of 20 composite leaching systems,including deionized water,lime water,calcium chloride,sodium carbonate,and sodium phosphate,through soil column leaching tests.The aim was to evaluate their impact on soil pH,total Cr,and Cr(Ⅵ)removal,and to examine the transformation of various Cr species during the leaching process.Results reveal that lime water and sodium phosphate were particularly effective in stabilizing Cr(Ⅵ)and neutralizing soil pH,while total Cr removal amount ranged from 197.4 mg/kg to 1671.6 mg/kg and Cr(Ⅵ)removal amount ranged from 113.2mg/kg to 316.8mg/kg.We also find that using 0.2 mol/L citric acid,0.1 mol/L hydrochloric acid,and 1.2 mL/g lime solution adjusted soil pH to 7.37,with average removal efficiencies of 34.6%.for total Cr and 72.7%for Cr(Ⅵ).Overall,our results suggest that the combined use of lime water and sodium phosphate is an effective strategy for remediating chromium-contaminated soil,particularly for stabilizing unleached Cr and adjusting soil pH.展开更多
This study addresses the global problem of the detoxification of cadmium(Cd)-containing solid waste by developing an eco-friendly thiosulfate system for extracting the negative electrode materials from spent Ni–Cd ba...This study addresses the global problem of the detoxification of cadmium(Cd)-containing solid waste by developing an eco-friendly thiosulfate system for extracting the negative electrode materials from spent Ni–Cd batteries and proposing an ultraviolet(UV)photolysis technology for the green recycling of the Cd in the resultant leached solution.Cd extraction is performed using both simple thiosulfate and cuprous thiosulfate systems,with the cuprous thiosulfate system exhibiting a superior leaching performance(80%),as compared with that of the simple thiosulfate system(36%).X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)analyses reveal the formation of copper sulfide on the surface of the Ni–Cd batteries leaching residue,which is confirmed by Cdleaching kinetics fitting using the shrinking-core model.Following UV exposure,95%of the Cd precipitates from the leaching solution to form CdS.Transmission electron microscopy(TEM)characterization and particle size distribution reveal that the CdS contains 100–150 nm-diameter spherical particles with compact surface structures.Electrochemical performance tests and UV–visible diffuse reflectance spectra(UV–Vis DRS)analyses demonstrate that the UV-photolysis product exhibits excellent photoelectric conversion characteristics.Photocatalytic activity tests of the recovered CdS confirm that the photocatalytic degradation ratio of methyl orange is 87%,indicating the successful green recycling of Cd from spent Ni–Cd batteries,which improves its potential application in the field of photocatalysis.展开更多
The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied....The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.展开更多
Oxidation pressure leaching was proposed to selectively dissolve Li from spent LiFePO_(4)batteries in a stoichiometric sulfuric acid solution.Using O_(2)as an oxidant and stoichiometric sulfuric acid as leaching agent...Oxidation pressure leaching was proposed to selectively dissolve Li from spent LiFePO_(4)batteries in a stoichiometric sulfuric acid solution.Using O_(2)as an oxidant and stoichiometric sulfuric acid as leaching agent,above 97%of Li was leached into the solution,whereas more than 99%of Fe remained in the leaching residue,enabling a relatively low cost for one-step separation of Li and Fe.And then,by adjusting the pH of leachate,above 95%of Li was recovered in the form of the Li_(3)PO_(4)product through iron removal and chemical precipitation of phosphate.展开更多
The study is focused on the extraction of valuable metals from automotive shredder residue(ASR)by different leaching solutions.First,ASR samples were roasted at 600°C to simulate a thermal treatment processing.Di...The study is focused on the extraction of valuable metals from automotive shredder residue(ASR)by different leaching solutions.First,ASR samples were roasted at 600°C to simulate a thermal treatment processing.Distilled water,citric and sulphuric acid were preliminarily investigated,thus two further full factorial systems entailing H2SO4–H2O2and H2SO4–H2O2–Fe3+were tested.The preliminary experimental results showed that0.1 mol·L-1H2SO4solution extracted 100%of Cu,Fe and Zn,whereas citric acid leached 100%of Zn and Pb,59%of Fe and 62%of Cu;whereas,H2SO4–H2O2and H2SO4–H2O2–Fe3+(Fenton's)leaching media showed that Cu,Fe and Zn can be extracted simultaneously and completely from the ASR ashes before final disposal.展开更多
The extraction of gold from refractory gold ores(RGOs)without side reactions is an extremely promising endeavor.However,most RGOs contain large amounts of sulfide,such as pyrite.Thus,investigation of the influence of ...The extraction of gold from refractory gold ores(RGOs)without side reactions is an extremely promising endeavor.However,most RGOs contain large amounts of sulfide,such as pyrite.Thus,investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs.In this work,the effects of pyrite on the stability of the thiourea system were systematically investigated under different conditions.Results showed that the decomposition rate of thiourea was accelerated sharply in the presence of pyrite.The effect of pyrite on gold recovery in thiourea leaching systems was then confirmed via a series of experiments.The decomposition efficiency of thiourea decreased by 40%and the recovery efficiency of gold increased by 56%after the removal of sulfide by roasting.Under optimal conditions,the efficiency of the gold recovery system increased to 83.69%and only 57.92%of thiourea decomposition was observed.The high consumption of thiourea by the leaching system may be attributed to not only adsorption by mineral particles but also catalytic decomposition by some impurities in the ores,such as pyrite and soluble ferric oxide.展开更多
The kinetics of the catalytical oxidation acid leaching of arsenopyrite is studied in the HNO<sub>3</sub>-H<sub>2</sub>SO<sub>4</sub>-O<sub>2</sub> aqueous system. In ad...The kinetics of the catalytical oxidation acid leaching of arsenopyrite is studied in the HNO<sub>3</sub>-H<sub>2</sub>SO<sub>4</sub>-O<sub>2</sub> aqueous system. In addition to the effect of reaction time on the extraction of arsenopyrite and distribution of products, the effects of operation factors and several additives on the reaction rate are also investigated. The experi mental results show that the oxidation rate is greatly dependent on nitric acid concentration, average radius of samples and acid concentration. The elemental sulphur produced does not interfere with the progress of the reacation process. It is found that a shrinking core model with chemical reaction controlling, which is expressed as 1-（1-α）<sup>1/3</sup>=kt, may be adopted to describe the kinetics results. The apparent activation energy is tested to be 23. 6 kJ/mol.展开更多
The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosi...The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosite(Pb-J)were 130℃,30 g/L H_(2)SO_(4),15 g/L Fe^(3+),and an oxygen partial pressure of 0.4 MPa.Furthermore,increased Fe^(3+)concentration and oxygen partial pressure did not enhance jarosite formation.Conversely,lowering the temperature and increasing the H_(2)SO_(4) concentration facilitated PbSO_(4) formation and inhibited its further conversion to Pb-J.Additionally,the effects of potassium sulfate,sodium sulfate,and high concentrations of zinc sulfate on the phase transformation of galena were examined through leaching tests,XRD,SEM-EDS,and FT-IR analyses.All three sulfates inhibited the conversion of galena to Pb-J.Among these,potassium sulfate prevented Pb-J formation and converted it more thoroughly into potassium jarosite.However,high concentrations of zinc sulfate facilitated the crystallization of both PbSO_(4) and Pb-J,which altered the morphology of the product.Zinc ions coprecipitated with Pb-J,thereby integrating into the product.展开更多
In view of the difference in coordination capacity of the glycine ion(Gly−),a selective leaching process for treating with spent lithium-ion batteries(LIBs)in the alkaline glycinate system was proposed.The effects of ...In view of the difference in coordination capacity of the glycine ion(Gly−),a selective leaching process for treating with spent lithium-ion batteries(LIBs)in the alkaline glycinate system was proposed.The effects of retention time,leaching temperature,concentration of glycine ligand,liquid-solid ratio(L/S),pH,stirring speed,and H_(2)O_(2) dosage on the leaching efficiency of valuable metals and the dissolution of impurities were investigated.When the spent LIBs were leached in 3 mol/L glycine aqueous solution with pH of 8,L/S of 5 mL:1 g and H_(2)O_(2) dosage of 5 vol.%at 90℃and stirring speed of 400 r/min for 3 h,lithium,cobalt,nickel,and manganese recoveries were 96.31%,83.18%,91.56%,and 31.16%,respectively,but Ca,Al,Fe,and Cu were almost insoluble.Meanwhile,the kinetic study showed that the activation energies for the leaching of Li,Co,Ni,and Mn were all in the range of 45−61 kJ/mol.The results indicate that the leaching process is all controlled by chemical reactions.展开更多
In order to explore the leaching law of different elements in the composite cementitious system composed of ferrous extraction tailing of nickel slag(FETNS)and ordinary Portland cement(OPC),element leaching test under...In order to explore the leaching law of different elements in the composite cementitious system composed of ferrous extraction tailing of nickel slag(FETNS)and ordinary Portland cement(OPC),element leaching test under different influencing factors was designed with the aid of ICP-OES,XRD,and SEM-EDS.The experimental results show that,with the extension of leaching time,the continuous hydration reaction in the system enables the leaching amount of Si,Al,Mg,and Ca elements to show an overall downward trend.In the alkaline environment,the more sufficient hydration reaction consumes more soluble elements,resulting in a significantly smaller leaching amount than that in the neutral environment.Temperature is also an important factor affecting the leaching of elements.The rise of temperature promotes the dissolution of amorphous phases Si,Al,and Mg in the system,leading to increased leaching amount and higher consumption of C_(2)S and C_(3)S,generating more reaction products.In addition,the content and fineness of FETNS also have a significant effect on the element leaching of the composite cementitious system.More importantly,this paper clarifies the leaching safety of internal heavy metal elements when FETNS is used under the above conditions,which provides a scientific guarantee for the safe and efficient application of FETNS in building materials.展开更多
The efficient extraction and separation of valuable metal elements from coal gasification fine slag(CGFS)are crucial for the comprehensive high-value utilization of its constituents.This study focused on the carbon-ri...The efficient extraction and separation of valuable metal elements from coal gasification fine slag(CGFS)are crucial for the comprehensive high-value utilization of its constituents.This study focused on the carbon-rich components of CGFS(CGFS-H)and systematically investigates the selective leaching behavior of Fe^(3+),Al^(3+)and Ca^(2+)using three organic acid extractants,i.e.,citric acid,tartaric acid,and tetrasodium iminodisuccinate.Additionally,the stepwise leaching of iron,aluminum and calcium from CGFS-H is explored.The selective dissolution mechanisms of these metals by different organic acids are elucidated through X-ray diffraction(XRD),X-ray fluorescence(XRF),and scanning electron microscopy(SEM)analyses.The results indicate that tetrasodium iminodisuccinate exhibits the highest leaching selectivity for Fe^(3+),while tartaric acid demonstrateds a comparable affinity for both Fe^(3+)and Al^(3+).In contrast citric acid shows superior selectivity toward Ca^(2+).The leaching yield of Fe^(3+),Al^(3+)and Ca^(2+)after sequential leaching with the three organic acids were 79.8%,65.08%and 78.6%,respectively.These findings confirm that effective and selective separation of Fe^(3+),Al^(3+)and Ca^(2+)from CGFS-H can be achieved via optimized organic acid-based leaching strategies.This advancement provides a critical foundation for developing Ca/Fe/Al hydrotalcite materials using CGFS-H as a sustainable feedstock,thereby facilitating the transformation of waste residue into high-value functional materials and promoting resourceefficient utilization of coal gasification fine slag.展开更多
The leaching mechanism of gallium(Ga)and germanium(Ge)from zinc powder replacement residue(ZPRR)was investigated through ultrasonic-assisted sulfuric acid leaching.Characterization via XRD,SEM,XPS,and FT-IR revealed t...The leaching mechanism of gallium(Ga)and germanium(Ge)from zinc powder replacement residue(ZPRR)was investigated through ultrasonic-assisted sulfuric acid leaching.Characterization via XRD,SEM,XPS,and FT-IR revealed that ultrasonic treatment promotes the dehydration of H_(4)SiO_(4)colloids,thereby reducing their adsorption capacities for Ga and Ge complexes.Additionally,ultrasound enhances the dissolution of CaS in H_(2)SO_(4),increasing H_(2)S production,which aids in the reduction of Fe^(3+)and mitigates iron precipitate formation.Process parameters including ultrasonic power(0-450 W),temperature(100-120℃),and leaching time(30-120 min)were systematically optimized,achieving optimal leaching efficiencies of Ga and Ge at 95.7%and 94.5%,respectively.展开更多
The leaching process and kinetic behavior of lepidolite in hydrochloric acid were explored systematically.The influence of leaching conditions on the leaching efficiency of valuable metals in lepidolite was investigat...The leaching process and kinetic behavior of lepidolite in hydrochloric acid were explored systematically.The influence of leaching conditions on the leaching efficiency of valuable metals in lepidolite was investigated.Under optimized conditions,the leaching efficiencies of Li,K,Rb,Cs and Al are 92.02%,93.31%,88.59%,86.75%and 81.07%,respectively.Kinetics research results show that the leaching process conforms to the shrinking core model that is under the mixed control of chemical reaction and diffusion through the solid product layer.In addition,the contribution of solid product layer diffusion to the leaching gradually expands as the temperature rises,but it is still significantly less than the contribution of chemical reaction.Cost saving in the neutralizing agent and leaching processes makes hydrochloric acid an economical leaching agent for lepidolite.Finally,the Li2CO3 product with a purity of 99.89%was synthesized from the hydrochloric acid leachate.展开更多
Phosphorus(P)leaching in alkaline soils,exacerbated by excessive fertilizer application,represents a significant pathway for P loss.While soil pore structure and texture critically regulate P transport,mechanisms gove...Phosphorus(P)leaching in alkaline soils,exacerbated by excessive fertilizer application,represents a significant pathway for P loss.While soil pore structure and texture critically regulate P transport,mechanisms governing P loss in texturally diverse alkaline soils remain unclear.This study investigated P leaching dynamics and transport parameters across four alkaline soil textures(silty clay,clay loam,loam,sandy loam)using a one-dimensional convective-diffusion equation(CDE)based on column experiments.Results indicated that phosphorus leaching kinetics were predominantly governed by diffusion transport,evidenced by low Peclet numbers(P_(e))(ranged from 0.02 to 0.31)across varying textures and initial P concentrations(C_(0)).Comparative analysis of transport parameters revealed significant textural effects on dispersion coefficient(D),retardation factor(R),pore water velocity(V),P_(e),and diffusion coefficient(λ)(F>523.42,p<0.001).Among these,only D,P_(e) andλexhibited substantial differences in response to variations in C_(0)(F>89.47,p<0.001).Saturated hydraulic conductivity(K_(s))(R^(2)=62.9%,p<0.01)and total pore area(A)(R^(2)=12.4%,p<0.01)emerged as primary regulators of P leaching.Enhanced clay content increased total pore area while reducing average pore diameter,concurrently decreasing pore water velocity and saturated infiltration rates.These textural modifications amplified diffusive P transport within soil matrices.The findings provide mechanistic insights into texturedependent P mobility in alkaline environments,informing targeted strategies for agricultural phosphorus management.展开更多
Heavy metal contamination of soil is one of the major challenges to sustainable agriculture.This contamination can be transmitted through the soil food chain and poses a serious threat to human health.In this study,we...Heavy metal contamination of soil is one of the major challenges to sustainable agriculture.This contamination can be transmitted through the soil food chain and poses a serious threat to human health.In this study,we found that freeze-thaw leaching(FTL)effectively complements the low removal rate of chemical leaching,and investigated the effects of different numbers of FTL on Cd contamination,soil chemical properties and microbial communities.The results showed that repeated FTL significantly reduced(P<0.05)the total Cd content in the top soil(19.02%-49.35%)and subsoil(0.41%-21.13%)and promoted the transformation of Cd to a more stable form,mainly through various removal mechanisms such as complexation,ion-exchange,and chemical precipitation.This finding was supported by reductions in several soil properties,including pH,available potassium(AK),and available phosphorus(AP).FTL treatment initially increased the bioavailability of Cd compared to chemical leaching,but bioavailability of Cd progressively decreased as the number of freeze-thaw cycles increased.Additionally,FTL reduced the richness and diversity of bacteria communities,destabilized ecological symbiotic networks,while increasing the richness and diversity of fungi in the soil.Various model analyses indicated that FTL treatment,available Cd,soil pH,AP and AK were the key drivers influencing the changes in microbial community structure.This study provides new insights and scientific bases for the effective management of heavy metal pollution in agricultural soils,the restoration of ecosystem health,and the improvement of soil sustainability.展开更多
Microwave roasting self-leaching is an innovative method for recovering gold from high-sulfur refractory gold concentrates,without using deadly toxic cyanide reagents.However,the mechanism of gold self-leaching,which ...Microwave roasting self-leaching is an innovative method for recovering gold from high-sulfur refractory gold concentrates,without using deadly toxic cyanide reagents.However,the mechanism of gold self-leaching,which relies on lixiviants prepared using volatilized sulfur obtained from roasting,has not been fully elucidated.This study employs the response surface methodology to optimize processing parameters,resulting in an increased gold extraction rate of 96.18%.Analytical factorization and the Tafel curve indicate that CuSO_(4) and NH_(3)·H_(2)O significantly influence the self-leaching process.Furthermore,X-ray photoelectron spectroscopy(XPS)analysis reveals that S^(2−),S_(2)^(2−),polysulfides(S_(n)^(2−)),and thiosulfate(S_(2)O_(3)^(2−))are involved in the gold leaching reaction,with S^(2−),S_(2)^(2−),and S_(n)^(2−) serving as primary ligands for gold complexation.The role of S_(2)O_(3)^(2−) in the early stages of the gold-leaching reaction is also noteworthy.The copper–ammonia complex catalyzes the self-leaching gold reaction;however,an improper addition ratio can lead to copper-sulfur compound precipitates,reducing the extraction rate.展开更多
Ida2--H2O system（iminodiacetate aqueous solution） was used to leach a low grade zinc oxide ore for Zn extraction.The effects of leaching time,liquid-solid ratio（L/S）,total concentration of Ida2-（[Ida2-]T）,leachi...Ida2--H2O system（iminodiacetate aqueous solution） was used to leach a low grade zinc oxide ore for Zn extraction.The effects of leaching time,liquid-solid ratio（L/S）,total concentration of Ida2-（[Ida2-]T）,leaching temperature and pH on Zn leaching recovery and the dissolution of impurities such as Ca,Mg,Cu,Ni,Fe,Pb and Cd were investigated.Results show that Ca,Mg and Fe in ores were hardly dissolved in alkalescent iminodiacetate aqueous solution,while valuable metals such as Cu,Ni,Pb and Cd were partly dissolved into leaching liquor with Zn.The recovery of Zn reaches 76.6% when the ores were leached for 4 h at 70 ℃ by 0.9 mol/L iminodiacetate aqueous solution with pH of 8 and L/S of 5：1.展开更多
To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures rangi...To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.展开更多
Gold bearing pyrite leaching was conducted in H2SO4-Fe2（SO4）3 system at different reaction temperatures,with different ferric ion concentrations,sulfuric acid concentrations and stirring speeds.The leaching kinetics...Gold bearing pyrite leaching was conducted in H2SO4-Fe2（SO4）3 system at different reaction temperatures,with different ferric ion concentrations,sulfuric acid concentrations and stirring speeds.The leaching kinetics and mechanism were studied.When the temperature ranged between 30-75 °C,the pyrite leaching was mainly controlled by chemical reaction with positive correlation to the ferric ion concentration.The activation energy obtained from Arrhenius empirical formula is 51.39 k J/mol.The EDS and XPS analyses suggest that the oxidation of sulfur within pyrite is through a series of intermediate stages,and eventually is oxidized to sulphate accompanied with the formation of element sulfur.This indicates a thiosulfate oxidation pathway of the gold bearing pyrite oxidation in H2SO4-Fe2（SO4）3 system.展开更多
基金supported by the National Key Research and Development Program of China(No.2023YFC3707902)China Postdoctoral Science Foundation(No.2024M752168)+1 种基金Jiangsu Funding Programfor Excellent Postdoctoral Talent(No.2024ZB393)the National Natural Science Foundation of China(No.42407126).
文摘Chemical leaching techniques have been proven effective in removing heavymetal contaminants fromsoil using various leaching agents.Previous research has shown that both singleagent and composite leaching systems have been applied for the remediation of chromiumcontaminated soils,with varying degrees of success depending on soil type and contaminant form.However,the removal rate of total chromium(Cr)and hexavalent chromium(Cr(Ⅵ))often fluctuates based on the chemical composition of the leaching agents,as well as the soil’s physicochemical properties,such as pH and Cr speciation stability.Therefore,this study investigates the effectiveness of 20 composite leaching systems,including deionized water,lime water,calcium chloride,sodium carbonate,and sodium phosphate,through soil column leaching tests.The aim was to evaluate their impact on soil pH,total Cr,and Cr(Ⅵ)removal,and to examine the transformation of various Cr species during the leaching process.Results reveal that lime water and sodium phosphate were particularly effective in stabilizing Cr(Ⅵ)and neutralizing soil pH,while total Cr removal amount ranged from 197.4 mg/kg to 1671.6 mg/kg and Cr(Ⅵ)removal amount ranged from 113.2mg/kg to 316.8mg/kg.We also find that using 0.2 mol/L citric acid,0.1 mol/L hydrochloric acid,and 1.2 mL/g lime solution adjusted soil pH to 7.37,with average removal efficiencies of 34.6%.for total Cr and 72.7%for Cr(Ⅵ).Overall,our results suggest that the combined use of lime water and sodium phosphate is an effective strategy for remediating chromium-contaminated soil,particularly for stabilizing unleached Cr and adjusting soil pH.
基金financially supported by the National Natural Science Foundation of China(No.52104349)Henan Provincial Science and Technology R&D Plan Joint Fund Project(No.232103810032)+1 种基金the Funds for HAUST Young Cadre Teacher(No.400213450022)supporting by China Postdoctoral Science Foundation(No.2022M721031)。
文摘This study addresses the global problem of the detoxification of cadmium(Cd)-containing solid waste by developing an eco-friendly thiosulfate system for extracting the negative electrode materials from spent Ni–Cd batteries and proposing an ultraviolet(UV)photolysis technology for the green recycling of the Cd in the resultant leached solution.Cd extraction is performed using both simple thiosulfate and cuprous thiosulfate systems,with the cuprous thiosulfate system exhibiting a superior leaching performance(80%),as compared with that of the simple thiosulfate system(36%).X-ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS)analyses reveal the formation of copper sulfide on the surface of the Ni–Cd batteries leaching residue,which is confirmed by Cdleaching kinetics fitting using the shrinking-core model.Following UV exposure,95%of the Cd precipitates from the leaching solution to form CdS.Transmission electron microscopy(TEM)characterization and particle size distribution reveal that the CdS contains 100–150 nm-diameter spherical particles with compact surface structures.Electrochemical performance tests and UV–visible diffuse reflectance spectra(UV–Vis DRS)analyses demonstrate that the UV-photolysis product exhibits excellent photoelectric conversion characteristics.Photocatalytic activity tests of the recovered CdS confirm that the photocatalytic degradation ratio of methyl orange is 87%,indicating the successful green recycling of Cd from spent Ni–Cd batteries,which improves its potential application in the field of photocatalysis.
基金Project (41271330) supported by the National Natural Science Foundation of China
文摘The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.
基金the financial supports from the National Natural Science Foundation of China(Nos.51804083,52104395,21906031)the Natural Science Foundation of Guangdong Province,China(No.2019A1515011628)+1 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2017B090907026)the Special Program of Guangdong Academy of Sciences,China(Nos.2019GDASYL-0103069,2020GDASYL-0104027,2020GDASYL-0302004,2020GDASYL-0302009,2021GDASYL-0302004)。
文摘Oxidation pressure leaching was proposed to selectively dissolve Li from spent LiFePO_(4)batteries in a stoichiometric sulfuric acid solution.Using O_(2)as an oxidant and stoichiometric sulfuric acid as leaching agent,above 97%of Li was leached into the solution,whereas more than 99%of Fe remained in the leaching residue,enabling a relatively low cost for one-step separation of Li and Fe.And then,by adjusting the pH of leachate,above 95%of Li was recovered in the form of the Li_(3)PO_(4)product through iron removal and chemical precipitation of phosphate.
文摘The study is focused on the extraction of valuable metals from automotive shredder residue(ASR)by different leaching solutions.First,ASR samples were roasted at 600°C to simulate a thermal treatment processing.Distilled water,citric and sulphuric acid were preliminarily investigated,thus two further full factorial systems entailing H2SO4–H2O2and H2SO4–H2O2–Fe3+were tested.The preliminary experimental results showed that0.1 mol·L-1H2SO4solution extracted 100%of Cu,Fe and Zn,whereas citric acid leached 100%of Zn and Pb,59%of Fe and 62%of Cu;whereas,H2SO4–H2O2and H2SO4–H2O2–Fe3+(Fenton's)leaching media showed that Cu,Fe and Zn can be extracted simultaneously and completely from the ASR ashes before final disposal.
基金This work was financially supported by the National Natural Science Foundation of China(No.51922108)the Hunan Natural Science Foundation(No.2019JJ20031)the Hunan Key Research and Development Program(No.2019SK2061).
文摘The extraction of gold from refractory gold ores(RGOs)without side reactions is an extremely promising endeavor.However,most RGOs contain large amounts of sulfide,such as pyrite.Thus,investigation of the influence of sulfide on the gold leaching process is important to maximize the utilization of RGOs.In this work,the effects of pyrite on the stability of the thiourea system were systematically investigated under different conditions.Results showed that the decomposition rate of thiourea was accelerated sharply in the presence of pyrite.The effect of pyrite on gold recovery in thiourea leaching systems was then confirmed via a series of experiments.The decomposition efficiency of thiourea decreased by 40%and the recovery efficiency of gold increased by 56%after the removal of sulfide by roasting.Under optimal conditions,the efficiency of the gold recovery system increased to 83.69%and only 57.92%of thiourea decomposition was observed.The high consumption of thiourea by the leaching system may be attributed to not only adsorption by mineral particles but also catalytic decomposition by some impurities in the ores,such as pyrite and soluble ferric oxide.
基金Financially supported by the National Natural Science Foundation of China
文摘The kinetics of the catalytical oxidation acid leaching of arsenopyrite is studied in the HNO<sub>3</sub>-H<sub>2</sub>SO<sub>4</sub>-O<sub>2</sub> aqueous system. In addition to the effect of reaction time on the extraction of arsenopyrite and distribution of products, the effects of operation factors and several additives on the reaction rate are also investigated. The experi mental results show that the oxidation rate is greatly dependent on nitric acid concentration, average radius of samples and acid concentration. The elemental sulphur produced does not interfere with the progress of the reacation process. It is found that a shrinking core model with chemical reaction controlling, which is expressed as 1-（1-α）<sup>1/3</sup>=kt, may be adopted to describe the kinetics results. The apparent activation energy is tested to be 23. 6 kJ/mol.
基金Projects(2023AG05008,202302AB080012)supported by the Yunnan Major Scientific and Technological Program,ChinaProject(202405AC350015)supported by the Science and Technology Talent Programme of Yunnan Province,China。
文摘The phase transformation of galena in H_(2)SO_(4)-Fe_(2)(SO_(4))_(3) system under oxygen pressure was investigated.Results indicated that the critical conditions for the phase transformation of galena into lead jarosite(Pb-J)were 130℃,30 g/L H_(2)SO_(4),15 g/L Fe^(3+),and an oxygen partial pressure of 0.4 MPa.Furthermore,increased Fe^(3+)concentration and oxygen partial pressure did not enhance jarosite formation.Conversely,lowering the temperature and increasing the H_(2)SO_(4) concentration facilitated PbSO_(4) formation and inhibited its further conversion to Pb-J.Additionally,the effects of potassium sulfate,sodium sulfate,and high concentrations of zinc sulfate on the phase transformation of galena were examined through leaching tests,XRD,SEM-EDS,and FT-IR analyses.All three sulfates inhibited the conversion of galena to Pb-J.Among these,potassium sulfate prevented Pb-J formation and converted it more thoroughly into potassium jarosite.However,high concentrations of zinc sulfate facilitated the crystallization of both PbSO_(4) and Pb-J,which altered the morphology of the product.Zinc ions coprecipitated with Pb-J,thereby integrating into the product.
基金Projects(51974137,52274299)supported by the National Natural Science Foundation of ChinaProject(2023M733190)supported by the China Postdoctoral Science Foundation。
文摘In view of the difference in coordination capacity of the glycine ion(Gly−),a selective leaching process for treating with spent lithium-ion batteries(LIBs)in the alkaline glycinate system was proposed.The effects of retention time,leaching temperature,concentration of glycine ligand,liquid-solid ratio(L/S),pH,stirring speed,and H_(2)O_(2) dosage on the leaching efficiency of valuable metals and the dissolution of impurities were investigated.When the spent LIBs were leached in 3 mol/L glycine aqueous solution with pH of 8,L/S of 5 mL:1 g and H_(2)O_(2) dosage of 5 vol.%at 90℃and stirring speed of 400 r/min for 3 h,lithium,cobalt,nickel,and manganese recoveries were 96.31%,83.18%,91.56%,and 31.16%,respectively,but Ca,Al,Fe,and Cu were almost insoluble.Meanwhile,the kinetic study showed that the activation energies for the leaching of Li,Co,Ni,and Mn were all in the range of 45−61 kJ/mol.The results indicate that the leaching process is all controlled by chemical reactions.
基金Funded by the Science and Technology Program of Gansu Province(Nos.23JRRA799 and 24JRRA213)the National Natural Science Foundation of China(Nos.52178216,52008196,and U21A20150)。
文摘In order to explore the leaching law of different elements in the composite cementitious system composed of ferrous extraction tailing of nickel slag(FETNS)and ordinary Portland cement(OPC),element leaching test under different influencing factors was designed with the aid of ICP-OES,XRD,and SEM-EDS.The experimental results show that,with the extension of leaching time,the continuous hydration reaction in the system enables the leaching amount of Si,Al,Mg,and Ca elements to show an overall downward trend.In the alkaline environment,the more sufficient hydration reaction consumes more soluble elements,resulting in a significantly smaller leaching amount than that in the neutral environment.Temperature is also an important factor affecting the leaching of elements.The rise of temperature promotes the dissolution of amorphous phases Si,Al,and Mg in the system,leading to increased leaching amount and higher consumption of C_(2)S and C_(3)S,generating more reaction products.In addition,the content and fineness of FETNS also have a significant effect on the element leaching of the composite cementitious system.More importantly,this paper clarifies the leaching safety of internal heavy metal elements when FETNS is used under the above conditions,which provides a scientific guarantee for the safe and efficient application of FETNS in building materials.
基金Supported by National Natural Science Foundation(52374279)。
文摘The efficient extraction and separation of valuable metal elements from coal gasification fine slag(CGFS)are crucial for the comprehensive high-value utilization of its constituents.This study focused on the carbon-rich components of CGFS(CGFS-H)and systematically investigates the selective leaching behavior of Fe^(3+),Al^(3+)and Ca^(2+)using three organic acid extractants,i.e.,citric acid,tartaric acid,and tetrasodium iminodisuccinate.Additionally,the stepwise leaching of iron,aluminum and calcium from CGFS-H is explored.The selective dissolution mechanisms of these metals by different organic acids are elucidated through X-ray diffraction(XRD),X-ray fluorescence(XRF),and scanning electron microscopy(SEM)analyses.The results indicate that tetrasodium iminodisuccinate exhibits the highest leaching selectivity for Fe^(3+),while tartaric acid demonstrateds a comparable affinity for both Fe^(3+)and Al^(3+).In contrast citric acid shows superior selectivity toward Ca^(2+).The leaching yield of Fe^(3+),Al^(3+)and Ca^(2+)after sequential leaching with the three organic acids were 79.8%,65.08%and 78.6%,respectively.These findings confirm that effective and selective separation of Fe^(3+),Al^(3+)and Ca^(2+)from CGFS-H can be achieved via optimized organic acid-based leaching strategies.This advancement provides a critical foundation for developing Ca/Fe/Al hydrotalcite materials using CGFS-H as a sustainable feedstock,thereby facilitating the transformation of waste residue into high-value functional materials and promoting resourceefficient utilization of coal gasification fine slag.
基金financially supported by the National Key Research and Development Program of China(No.2022YFC2904900)the National Natural Science Foundation of China(Nos.52204392,52274385,52204347)the Young Elite Scientists Sponsorship Program by CAST,China(No.2022QNRC001)。
文摘The leaching mechanism of gallium(Ga)and germanium(Ge)from zinc powder replacement residue(ZPRR)was investigated through ultrasonic-assisted sulfuric acid leaching.Characterization via XRD,SEM,XPS,and FT-IR revealed that ultrasonic treatment promotes the dehydration of H_(4)SiO_(4)colloids,thereby reducing their adsorption capacities for Ga and Ge complexes.Additionally,ultrasound enhances the dissolution of CaS in H_(2)SO_(4),increasing H_(2)S production,which aids in the reduction of Fe^(3+)and mitigates iron precipitate formation.Process parameters including ultrasonic power(0-450 W),temperature(100-120℃),and leaching time(30-120 min)were systematically optimized,achieving optimal leaching efficiencies of Ga and Ge at 95.7%and 94.5%,respectively.
基金supported by the National Natural Science Foundation of China(No.52122407)the National Key Research&Development Program of China(No.2022YF2906200)the Science and Technology Innovation Program of Hunan Province,China(No.2022RC3048)。
文摘The leaching process and kinetic behavior of lepidolite in hydrochloric acid were explored systematically.The influence of leaching conditions on the leaching efficiency of valuable metals in lepidolite was investigated.Under optimized conditions,the leaching efficiencies of Li,K,Rb,Cs and Al are 92.02%,93.31%,88.59%,86.75%and 81.07%,respectively.Kinetics research results show that the leaching process conforms to the shrinking core model that is under the mixed control of chemical reaction and diffusion through the solid product layer.In addition,the contribution of solid product layer diffusion to the leaching gradually expands as the temperature rises,but it is still significantly less than the contribution of chemical reaction.Cost saving in the neutralizing agent and leaching processes makes hydrochloric acid an economical leaching agent for lepidolite.Finally,the Li2CO3 product with a purity of 99.89%was synthesized from the hydrochloric acid leachate.
基金supported by the National Natural Science Foundation of China(Nos.42077067,42277329)the Projects of Talents Recruitment of GDUPT(No.XJ2005000301)。
文摘Phosphorus(P)leaching in alkaline soils,exacerbated by excessive fertilizer application,represents a significant pathway for P loss.While soil pore structure and texture critically regulate P transport,mechanisms governing P loss in texturally diverse alkaline soils remain unclear.This study investigated P leaching dynamics and transport parameters across four alkaline soil textures(silty clay,clay loam,loam,sandy loam)using a one-dimensional convective-diffusion equation(CDE)based on column experiments.Results indicated that phosphorus leaching kinetics were predominantly governed by diffusion transport,evidenced by low Peclet numbers(P_(e))(ranged from 0.02 to 0.31)across varying textures and initial P concentrations(C_(0)).Comparative analysis of transport parameters revealed significant textural effects on dispersion coefficient(D),retardation factor(R),pore water velocity(V),P_(e),and diffusion coefficient(λ)(F>523.42,p<0.001).Among these,only D,P_(e) andλexhibited substantial differences in response to variations in C_(0)(F>89.47,p<0.001).Saturated hydraulic conductivity(K_(s))(R^(2)=62.9%,p<0.01)and total pore area(A)(R^(2)=12.4%,p<0.01)emerged as primary regulators of P leaching.Enhanced clay content increased total pore area while reducing average pore diameter,concurrently decreasing pore water velocity and saturated infiltration rates.These textural modifications amplified diffusive P transport within soil matrices.The findings provide mechanistic insights into texturedependent P mobility in alkaline environments,informing targeted strategies for agricultural phosphorus management.
基金supported by the National Natural Science Foundation of China(No.42077135).
文摘Heavy metal contamination of soil is one of the major challenges to sustainable agriculture.This contamination can be transmitted through the soil food chain and poses a serious threat to human health.In this study,we found that freeze-thaw leaching(FTL)effectively complements the low removal rate of chemical leaching,and investigated the effects of different numbers of FTL on Cd contamination,soil chemical properties and microbial communities.The results showed that repeated FTL significantly reduced(P<0.05)the total Cd content in the top soil(19.02%-49.35%)and subsoil(0.41%-21.13%)and promoted the transformation of Cd to a more stable form,mainly through various removal mechanisms such as complexation,ion-exchange,and chemical precipitation.This finding was supported by reductions in several soil properties,including pH,available potassium(AK),and available phosphorus(AP).FTL treatment initially increased the bioavailability of Cd compared to chemical leaching,but bioavailability of Cd progressively decreased as the number of freeze-thaw cycles increased.Additionally,FTL reduced the richness and diversity of bacteria communities,destabilized ecological symbiotic networks,while increasing the richness and diversity of fungi in the soil.Various model analyses indicated that FTL treatment,available Cd,soil pH,AP and AK were the key drivers influencing the changes in microbial community structure.This study provides new insights and scientific bases for the effective management of heavy metal pollution in agricultural soils,the restoration of ecosystem health,and the improvement of soil sustainability.
基金supported by the National Natural Science Foundation of China(No.51974016).
文摘Microwave roasting self-leaching is an innovative method for recovering gold from high-sulfur refractory gold concentrates,without using deadly toxic cyanide reagents.However,the mechanism of gold self-leaching,which relies on lixiviants prepared using volatilized sulfur obtained from roasting,has not been fully elucidated.This study employs the response surface methodology to optimize processing parameters,resulting in an increased gold extraction rate of 96.18%.Analytical factorization and the Tafel curve indicate that CuSO_(4) and NH_(3)·H_(2)O significantly influence the self-leaching process.Furthermore,X-ray photoelectron spectroscopy(XPS)analysis reveals that S^(2−),S_(2)^(2−),polysulfides(S_(n)^(2−)),and thiosulfate(S_(2)O_(3)^(2−))are involved in the gold leaching reaction,with S^(2−),S_(2)^(2−),and S_(n)^(2−) serving as primary ligands for gold complexation.The role of S_(2)O_(3)^(2−) in the early stages of the gold-leaching reaction is also noteworthy.The copper–ammonia complex catalyzes the self-leaching gold reaction;however,an improper addition ratio can lead to copper-sulfur compound precipitates,reducing the extraction rate.
基金Project (2007CB613604) supported by the National Basic Research Program of China
文摘Ida2--H2O system（iminodiacetate aqueous solution） was used to leach a low grade zinc oxide ore for Zn extraction.The effects of leaching time,liquid-solid ratio（L/S）,total concentration of Ida2-（[Ida2-]T）,leaching temperature and pH on Zn leaching recovery and the dissolution of impurities such as Ca,Mg,Cu,Ni,Fe,Pb and Cd were investigated.Results show that Ca,Mg and Fe in ores were hardly dissolved in alkalescent iminodiacetate aqueous solution,while valuable metals such as Cu,Ni,Pb and Cd were partly dissolved into leaching liquor with Zn.The recovery of Zn reaches 76.6% when the ores were leached for 4 h at 70 ℃ by 0.9 mol/L iminodiacetate aqueous solution with pH of 8 and L/S of 5：1.
基金Project(2007CB613504)supported by the National Key Basic Research Program of ChinaProjects(51004033,50974035,51074047)supported by the National Natural Science Foundation of ChinaProject(2008BAB34B01)supported by National Science and Technology Support Plan of China during the 11th Five-Year Plan
文摘To analyze the thermodynamic characteristics of leaching process of converter slag, φ-pH diagram of V-Ti-H2O system at oxygen partial pressure of 0.5 MPa, ionic mass concentration of 0.1 mol/kg and temperatures ranging from 60 to 200 ℃ was obtained by recently published critically assessed standard Gibbs energies and activity coefficients of various species. When pH2, stable regions of V3＋, VO2＋ and VO2＋ exist in the stable region of TiO2. The pH values of stable regions of vanadium and titanium decrease and redox potentials become more positive with the temperature increasing. Vanadium and titanium could be separated by one-step leaching based on thermodynamics. The experiment results of pressure acid leaching of converter slag show that leaching rates of vanadium and titanium are 96.87% and 8.76% respectively, at 140 ℃ of temperature, 0.5 MPa of oxygen partial pressure, 0.055-0.075mm of particle size, 15：1 of liquid to solid ratio, 120 min of leaching time, 500 r/min of stirring speed and 200 g/L of initial acid concentration. Vanadium and titanium could be selectively separated in the pressure acid leaching process, and the experiment result is in agreement with thermodynamic calculation result.
基金Project(51474075)supported by the National Natural Science Foundation of China
文摘Gold bearing pyrite leaching was conducted in H2SO4-Fe2（SO4）3 system at different reaction temperatures,with different ferric ion concentrations,sulfuric acid concentrations and stirring speeds.The leaching kinetics and mechanism were studied.When the temperature ranged between 30-75 °C,the pyrite leaching was mainly controlled by chemical reaction with positive correlation to the ferric ion concentration.The activation energy obtained from Arrhenius empirical formula is 51.39 k J/mol.The EDS and XPS analyses suggest that the oxidation of sulfur within pyrite is through a series of intermediate stages,and eventually is oxidized to sulphate accompanied with the formation of element sulfur.This indicates a thiosulfate oxidation pathway of the gold bearing pyrite oxidation in H2SO4-Fe2（SO4）3 system.
