Sulfuric acid leaching process was applied to extract nickel from roasting-dissolving residue of a spent catalyst, the effect of different parameters on nickel extraction was investigated by leaching experiments, and ...Sulfuric acid leaching process was applied to extract nickel from roasting-dissolving residue of a spent catalyst, the effect of different parameters on nickel extraction was investigated by leaching experiments, and the leaching kinetics of nickel was analyzed. The experimental results indicate that the effects of particle size and sulfuric acid concentration on the nickel extraction are remarkable; the effect of reaction temperature is mild; while the effect of stirring speed in the range of 400-1 200 r/min is negligible. Decreasing particle size or increasing sulfuric acid concentration and reaction temperature, the nickel extraction efficiency is improved. 93.5% of nickel in residue is extracted under suitable leaching conditions, including particle size （0.074-0.100） mm, sulfuric acid concentration 30% （mass fraction）, temperature 80 ~C, reaction time 180 min, mass ratio of liquid to solid 10 and stirring speed 800 r/min. The leaching kinetics analyses shows that the reaction rate of leaching process is controlled by diffusion through the product layer, and the calculated activation energy of 15.8 kJ/mol is characteristic for a diffusion controlled process.展开更多
Production of petrochemical catalysts accounts for one of the largest shares of platinum group metals(PGMs) consumption;thus,recycling of spent petrochemical catalysts holds great economic value.Conventionally,PGMs ar...Production of petrochemical catalysts accounts for one of the largest shares of platinum group metals(PGMs) consumption;thus,recycling of spent petrochemical catalysts holds great economic value.Conventionally,PGMs are recovered through hydrometallurgical processes which have a low recovery efficiency and produce a large amount of waste.In this regard,this paper proposed a method to use iron-capturing PGMs based on CaO-Al_(2)O_(3)-Na_(2)O slag.This method avoided the formation of Fe-Si alloy and achieved efficient enrichment of PGMs.The droplet force model showed that the recovery efficiency of PGMs could be improved if the slag had low density and low viscosity.Based on this result,FactSage software optimized the composition of slag.Furthermore,the effect of B_(2)O_(3) on the 1400 ℃ liquidus of CaO-Al_(2)O_(3)-Na_(2)O_(3)-B_(2)O_(3) phase diagram was revealed.Moreover,it was found that the recovery efficiency of PGMs exceeded 99% under the following optimized conditions:basicity of 1.0,20 wt%Na_(2)O,15 wt% B_(2)O_(3),15 wt% Fe,3 wt% C and a temperature range of 1400-1500℃.The thermodynamic model revealed the mechanism of iron capture.Different chemical bonds prevented the formation of bonds between the alloy and slag,resulting in the separation of the slag from the alloy.PGMs particles and iron microspheres had significant surface Gibbs free energy.Only when iron microspheres and PGMs particles collided and fused with each other to reduce their surface area could the Gibbs free energy of the system be reduced.展开更多
A new technology for microwave pretreatment of spent catalyst on Zn extraction by HCl leaching was proposed and the temperature-change curve of spent catalyst under microwave irradiation was measured.The influence of ...A new technology for microwave pretreatment of spent catalyst on Zn extraction by HCl leaching was proposed and the temperature-change curve of spent catalyst under microwave irradiation was measured.The influence of microwave pretreatment temperature and microwave irradiation time on zinc extraction was investigated and the mechanism of microwave pretreatment for spent catalyst was analyzed.The results show that microwave pretreatment can greatly enhance the leaching rate of Zn.The Zn extraction reaches 96.58%under the conditions of microwave pretreatment temperature of 950℃and the microwave irradiation time of 12 min.The blocked pores of spent catalyst can be opened through microwave pretreatment,increasing the contact area of leaching reagent and zinc.展开更多
Hazardous wastes from the production of cleaner fuels,spent hydrodesulfurization(HDS)catalysts,pose a threat to the environment and the sustainability of rare metal resources.However,conventional recovery approaches a...Hazardous wastes from the production of cleaner fuels,spent hydrodesulfurization(HDS)catalysts,pose a threat to the environment and the sustainability of rare metal resources.However,conventional recovery approaches are limited by long processes,easy generation of waste liquids,and difficult reuse of recovery products.Herein,a SiO_(2)-Na_(2)O-B_(2)O_(3)-MgO-TiO_(2)glass phase extraction system was proposed for the full-component recycle from spent MoNi/γ-Al_(2)O_(3)catalysts to the materials,including the individual recovery of Mo and the synthesis of Ni^(2+)-doped glass–ceramics.96.7%of Ni and 99.8%of Al were extracted into the loaded glass in one step,while 95.3%of Mo was precipitated as molybdate and directly recovered with high separation factors(SF_(Mo/Ni)594.8,SF_(Mo/Al)8718.2)in one step.Moreover,the broadband near-infrared luminescence(1150-1700 nm)of glass–ceramics was triggered by Ni^(2+)in the octahedral crystal structure of Me_(3)O_(5)(Me=Mg,Al,Ti)by meltingannealing-crystallization processes,which provided it the potential to be applied in tunable lasers and broadband optical amplifiers for the wavelength-division-multiplexing transmission systems.The Ni^(2+)-doping mechanism was calculated using molecular dynamics simulations.This work emphasized the maximization of the reuse value for each metal resource from hazardous wastes while reducing the burden on the environment and achieving the recycling of rare metal resources with re-valorization.展开更多
This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw ma...This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw materials,incorporating CaO as an additive to fine-tune the slag's viscosity and density.By reducing FeO in the lead slag using waste graphite electrodes,pure Fe was obtained,effectively trapping the PGMs from the exhausted catalysts.The study explored the effects of reductant addition,trapping duration,slag basicity,and trapping temperature on the recovery rate of PGMs.The results indicated that a maximum recovery rate of 97.86%was achieved when the reductant was added at 1.5 times the theoretical amount,with a trapping duration of 60 minutes,a slag basicity of 0.7,and a trapping temperature of 1600℃.This research offered a greener pathway for the recovery of PGMs from spent automotive exhaust catalysts.展开更多
An attempt has been made to investigate and optimize the recovery of Ni and Al through sulphuric acid(3.0-5.5 mol/L)leaching under different operating conditions.From the leaching experiments,it was possible to extrac...An attempt has been made to investigate and optimize the recovery of Ni and Al through sulphuric acid(3.0-5.5 mol/L)leaching under different operating conditions.From the leaching experiments,it was possible to extract 98.5%of NiO and 40.7%of Al_(2)O_(3)under the conditions of 5.5 mol/L H_(2)SO_(4),reaction time of 4 h,solid-to-liquid ratio 0.2 g/mL,temperature of 358 K,particle size<100μm,200-250 r/min with 5.0 g catalyst dosage.The leached liquor Al was separated by selective crystallization using 1.4 mol/L KOH and Ni was separated by selective precipitation using 0.3 mol/L H_(2)C_(2)O_(4).From the studies,it is possible to recover around 97.9%of NiO having 98.3%purity,around 25%of Al_(2)O_(3)was also recovered as alum-(K)having 99%purity and 14.7%of Al_(2)O_(3)as a salt of Al-K-C_(2)O_(4)-SO_(4).Sulphuric acid was found to be a suitable leaching agent for selective leaching and it was also observed that alum-(K)can be selectively crystallized from sulphate solutions.The study also indicated the effective extraction and recovery of nickel and aluminium which were well supported by characterization studies using TG-DTA/DTG and XRD techniques.展开更多
Advanced technological achievements and the continuous growth of economy have made the disposal, recycle and reuse of industrial by-products a severe challenge. The cement industry is considered one of the key sectors...Advanced technological achievements and the continuous growth of economy have made the disposal, recycle and reuse of industrial by-products a severe challenge. The cement industry is considered one of the key sectors in this effort in successfully （in terms of not extenuating but improving some of the properties of the final product） absorbing large quantities of solid wastes, either as aggregates or as secondary cementitious materials. This not only contributes to the creation of an energy and CO2-emission depository （as commonly used raw materials are spared）, but also simultaneously alleviates the acute environmental burden caused by the irresponsible disposal of such by-products. In this study, the possibility of reusing spent fluid catalytic-cracking catalyst （FCC） as a supplementary cementing material （SCM） was examined. A series of tests were conducted, initially aiming at characterizing the material and thereafter evaluating its pozzolanic activity and its effect on the mechanical properties of blended cements. Major findings in this investigation revealed that the use of FCC as a mineral admixture in cement is feasible, strengthening the belief that siliceous glassy residues should represent a steady supply for the construction sector.展开更多
Traditionally,Ag-containing solid wastes are leached by nitric acid in order to recycle the noble metal.However,the huge amounts of emission of toxic nitrogen oxides demand the development of a new method for silver r...Traditionally,Ag-containing solid wastes are leached by nitric acid in order to recycle the noble metal.However,the huge amounts of emission of toxic nitrogen oxides demand the development of a new method for silver recycling.Recently,considering the Ce(Ⅳ)solution could be regenerated with electrolyzation method,our group invented a novel environmentally friendly process by using Ce(Ⅳ)as the oxidant to dissolve silver from the spent Ag/ɑ-Al_2O_3 catalysts without NO_x emission.To find out the optimal parameters,in this work,the leaching reaction was thoroughly investigated with respect to the temperature,oxidant and HNO_3 concentrations,stirring speed,and time.The optimized leaching reaction gave the leaching silver rate 99.8% in 1 h.The kinetic plots suggested a shrinking core model with the internal diffusion-controlled process and the activation energy of 38.83 k J·mol^(-1).The order in which the experimental conditions influence the reaction was determined through orthogonal analysis:temperature N oxidant concentration N HNO_3 concentration N stirring speed.展开更多
Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56....Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit.展开更多
Preparation of high purity ruthenium nitrosyl nitrate using spent Ru-Zn/ZrO_(2)catalyst was studied,including melting and leaching to obtain potassium ruthenate solution,reduction,dissolving,concentrating and drying t...Preparation of high purity ruthenium nitrosyl nitrate using spent Ru-Zn/ZrO_(2)catalyst was studied,including melting and leaching to obtain potassium ruthenate solution,reduction,dissolving,concentrating and drying to obtain ruthenium trichloride,nitrosation and hydrolysis to obtain ruthenium nitrosyl hydroxide,removing of K^(+)and Cl^(-),and neutralization with nitric acid.The effects of temperature,concentration,time and pH on the yield and purity of intermediates and final product were studied,and the optimum process conditions were obtained.The yield of ruthenium nitrosyl nitrate is 92%,the content of ruthenium in high purity product is 32.16%,and the content of Cl^(-)and K^(+)are much less than 0.005%.The reaction kinetics of ruthenium nitrosyl chloride to ruthenium nitrosyl hydroxide was studied.The reaction orders of Ru(NO)Cl_(3)at 40,55 and 70℃are 0.39,0.37 and 0.39,respectively,while those of KOH are 0.16,0.15 and 0.17,respectively.The activation energy is-2.33 k J/mol.展开更多
Oxidation of coke deposited on spent catalytic cracking catalysts was compared with that of coal and coal char via the non-isothermal oxidation means,i.e.the thermal-gravimetric analysis(TGA)and the differential therm...Oxidation of coke deposited on spent catalytic cracking catalysts was compared with that of coal and coal char via the non-isothermal oxidation means,i.e.the thermal-gravimetric analysis(TGA)and the differential thermal analysis(DTA).Oxidation kinetic parameters were further investigated by model-fitting methods.The test results showed that the oxidation of spent catalysts was a quite mild process,while coal and coal char experienced sharp weight loss during oxidation.The temperature for commencement and termination of oxidation increased in the following order:coal〈coal char〈spent catalysts,and the oxidation of the three tested materials displayed a self-catalytic nature,with their largest oxidation rate appearing at a weight percent of 24.96%,34.21%and 57.93%,respectively.The oxidation of spent catalysts obeyed a random nucleation model for the first-order reaction,with Ea=206.13 kJ/mol and lgA=10.10,and the oxidation of coal could be a diffusion-controlled reaction mechanism,with Ea=161.61 kJ/mol and lgA=7.74,while the oxidation of coal char also obeyed a random nucleation model for the first-order reaction,with Ea=149.36 k J/mol and lgA=7.89.展开更多
The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted...The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted leaching methods. The influence of microwave power, leaching time, leaching temperature, and NaOH concentration on the leaching efficiency of spent petrochemical catalyst was investigated. Under microwave-assisted conditions(600 W, 10 min, 90°C, 2.0 mol·L^(-1) NaOH, and 0.20 g·mL^(-1) solid–liquid ratio), the leaching efficiencies of V and Mo reached 94.35% and 96.23%, respectively. It has been confirmed that microwave energy has considerable potential to enhance the efficiency of the leaching process and reduce the leaching time. It is suggested that the enhancement of the leaching efficiencies of V and Mo can be attributed to the existence of a thermal gradient between solid and liquid and the generation of cracks on the mineral surface.展开更多
Aluminum recovery is a key issue for the overall recycling of valuable metals from spent catalysts. This paper focuses on the recovery and regeneration of alumina with high additional value from the spent hydrodesulfu...Aluminum recovery is a key issue for the overall recycling of valuable metals from spent catalysts. This paper focuses on the recovery and regeneration of alumina with high additional value from the spent hydrodesulfurization catalyst CoMo/Al_2O_3. The results indicate that 98.13% alumina is successfully leached from the treated spent catalysts by an alkaline leaching process under the conditions of 5 mol·L^(-1) sodium hydroxide,a liquid/solid ratio of 20 ml·g^(-1),a temperature of 160 0 C and a reaction time of 4 h. In the leaching residue, no difficult leaching compound is found and cobalt and nickel are enriched,both of which are conducive to the subsequent metal recovery step. The reaction order of aluminum leaching is 0.99. This reaction fits well with the interfacial chemical reaction model, and its apparent activation energy is calculated as 45.50 kJ mol^(-1). Subsequently, y-Al_2O_3 with a high specific surface area of 278.3 m^2·g^(-1), a mean size of 2.2 μm and an average pore size of 3.10 nm is then regenerated from the lixivium, indicating its suitability for use as a catalyst carrier. The recovery and regeneration of alumina from spent catalysts can not only significantly contribute to the total recycling of such hazardous spent catalysts but also provide a new approach for the preparation of y-Al_2O_3 with a high specific surface area using spent catalysts as the aluminum sources.展开更多
Spent catalyst used for denitration by selective catalytic reduction(spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO_(2)(~85 wt%) and the massive accumulation amount...Spent catalyst used for denitration by selective catalytic reduction(spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO_(2)(~85 wt%) and the massive accumulation amount(over 100,000 tons),therefore,value-added reutilization of titanium in spent SCR catalysts is considerably meaningful.In this paper,a novel method is proposed for converting the titanium oxide in spent SCR denitration catalysts to metallic titanium.Specifically,titanium dioxide(TiO_(2)) was firstly obtained from spent SCR denitration catalysts after removing the impurities by hydrometallurgy process.Then,TiO_(2) is converted to Ti_(2)CO by carbothermic reduction method,and Ti_(2)CO was further purified by oleic acid capture.Finally,by utilizing the as-prepared Ti_(2)CO as the consumable anode in the NaCl-KCl molten salt,high-purity metallic titanium was deposited at cathode,all confirming the feasibility for the conversion of low-grade TiO_(2) in the spent catalysts,from 60 wt% to high-purity metallic Ti(99.5 wt%), furthermore,the energy consumption of this process is 3950 kWh tonne-1 Ti,which is lower than that of most traditional titanium metallurgy methods.The method herein can provide new insights for the value-added recycling of titanium resources in urban mines.展开更多
The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using ...The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using 0.1–1.5 mol L^(-1) oxalic acid concentration was studied at 60℃–90℃.V and Fe were preferentially released(65%and 81%)compared with Al,Ti and W within 5 min due to the redox reactions of oxalic acid.The dissolved fractions of Fe,V,Al,Wand Ti increased with the increase of oxalic acid concentration and reaction temperature.The dissolution kinetic experiments were analysed and controlled diffusion with n<0.5 according to the Avrami dissolve reaction model(R^(2)>0.92).The Arrhenius parameters of the Ea values of Ti,W,V,Fe and Al from SDC with oxalic acid were 30,26,20,19 and 11 kJ mol^(-1),respectively.The obtained Avrami equation of V and Fe was successfully used to predict their leaching behaviour in oxalic acid.Toxicity characteristic leaching procedure revealed that the toxicity risk of Vand Fe metals from SDC after leaching with oxalic acid decreased to below 5 mg kg^(-1) residua.Overall,the leaching residua by oxalic acid indicated its safety for the environment.展开更多
Platinum group metals(PGMs),especially Pd,Pt,and Rh,have drawn great attention due to their unique features.Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various f...Platinum group metals(PGMs),especially Pd,Pt,and Rh,have drawn great attention due to their unique features.Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various factors.This work investigates the effect of various parameters including the acidity,extractant concentration,phase ratio A/O,and diluents on the Pd and Pt extraction and their stripping behaviors.The results show that the Pd and Pt are successfully separated from simulated leach liquor of spent automobile catalysts with monothioCyanex 272 and trioctylamine(TOA).Monothio-Cyanex 272 shows strong extractability and specific selectivity for Pd,and only one single stage is needed to recover more than 99.9% of Pd,leaving behind all the Pt,Rh,and base metals of Fe,Mg,Ce,Ni,Cu,and Co in the raffinate.The loaded Pd is efficiently stripped by acidic thiourea solutions.TOA shows strong extractability for Pt and Fe at acidity of 6 mol·L^(–1) HCl.More than 99.9% of Pt and all of the Fe are extracted into the organic phase after two stages of countercurrent extraction.Diluted HCl easily scrubs the loaded base metals(Fe,Cu,and Co).The loaded Pt is efficiently stripped by 1.0 mol·L^(–1) thiourea and 0.05–0.1 mol·L^(–1) Na OH solutions.Monothio-Cyanex 272 and TOA can realize the separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts.展开更多
Platinum(Pt)is a critical raw material for automotive catalytic converters due to its high-temperature stability,corrosion resistance and catalytic activity,whereas its limited primary resources and uneven distributio...Platinum(Pt)is a critical raw material for automotive catalytic converters due to its high-temperature stability,corrosion resistance and catalytic activity,whereas its limited primary resources and uneven distribution make it hard to meet the growing demand of platinum.Spent automotive catalyst(SAC)is currently the most important secondary resource of platinum,of which the platinum content is much higher than that of the primary platinum resources.The recovery process of platinum from spent automobile catalyst mainly consists of pretreatment followed by enrichment and refining,involving pyro-and hydrometallurgical techniques,among which enrichment and refining processes are extremely important for platinum recovery from spent automobile catalyst.This paper provides an overview of the technologies for platinum recovery from spent automotive catalyst.The emphasis is placed on the processes of enrichment and refining based on hydrometallurgical techniques.Future directions of research and development of platinum recovery from spent automobile catalyst are also proposed.展开更多
The chemical composition, structure and thermal stability of the spent FCC equilibrium catalyst from an oil refinery were characterized by XRD, FT-IR, DTA-TG, BET, complete chemical analysis, SEM, and XRF. The spent F...The chemical composition, structure and thermal stability of the spent FCC equilibrium catalyst from an oil refinery were characterized by XRD, FT-IR, DTA-TG, BET, complete chemical analysis, SEM, and XRF. The spent FCC equilibrium catalyst, clay, barium carbonate, and talc were used as the main raw materials to prepare the alumina abrasion-resistant ceramic balls to be used in the powder grinding mill for manufacture of architecture tiles. The results showed that after proper formulation study, the spent FCC equilibrium catalyst could replace industrial alumina to prepare high performance grinding balls. Meanwhile, the various performance indices of the grinding ball could meet the quality standard for similar products, and additionally, the energy saving effect was achieved in the operation of the grinding section, resulting in a successful comprehensive utilization of solid wastes.展开更多
Spent hydrogenation catalysts are important secondary resources due to richness in the valuable metals of Ni,Mo and V.Recovery of valuable metals from spent catalysts has high economic value and environmental benefits...Spent hydrogenation catalysts are important secondary resources due to richness in the valuable metals of Ni,Mo and V.Recovery of valuable metals from spent catalysts has high economic value and environmental benefits since they are hazardous wastes as well.Traditional recycling processes including hydrometallurgical leaching and soda roasting-leaching have disadvantages such as generating large amounts of wastewater,long process,and low recovery efficiency of valuable metals.Thus,this paper proposed synergistic enrichment of Ni,Mo and V via pyrometallurgical reduction at 1400-1500℃.The melting temperature and viscosity of slag were reduced through slag designing by software FactSage 7.1.The phase diagram of Al_(2)O_(3)-Cap-SiO_(2)-Na_(2)O-B_(2)O_(3)was drawn,and low-temperature region(≤1300℃)was selected as target slag composition.Ni,Mo,and V can be collaborative captured and recovered through the mutual solubility at molten state.Increasing the melting temperature and the amount of CaO,Na_(2)O and C were conducive to improving the metals recovery rates.The kilogram-scale experiments were carried out,and the recovery efficiencies of Ni,Mo and V were 98.3%,95.3%and 97.9%under optimized conditions:at 1500℃,with the basicity of 1.0,13.1 wt%SiO_(2),7.0 wt%B_(2)O_(3),7.7 wt%Na_(2)O and 20.0wt%C.The distribution behavior of valuable metals was clarified by investigating the melting process of slag and the reduction in valuable metals.Ni was preferentially reduced and acted as a capturing agent,which captured other metals to form NiMoV alloys.展开更多
A large number of spent selective catalytic reduction(SCR)denitration catalysts are produced after the ultra-low emission transformation of coal-fired power plants in China.According to the China’s“Directory of Nati...A large number of spent selective catalytic reduction(SCR)denitration catalysts are produced after the ultra-low emission transformation of coal-fired power plants in China.According to the China’s“Directory of National Hazardous Wastes(Version 2021)”,these spent vanadium-tungsten-titanium catalysts are classified as“HW50”hazardous waste,and their disposal and utilization processes have been strictly controlled.Thus,an effective and low-cost technique was developed to treat and utilize these spent SCR catalysts by the vanadium-titanium magnetite sintering process.Effects of adding spent SCR catalysts on the sintering production process and product quality indexes of sinter were studied.The results showed that adding spent SCR catalysts can improve the sintering granulation and green feed permeability,thereby increasing the productivity and flame front speed.When the addition proportion of spent SCR catalysts is less than 1 wt.%,the performance indexes of the finished sinter are basically equal to those of the finished sinter without adding spent SCR catalysts.Further increasing the proportion of spent SCR catalysts to 2.0 wt.%results in a decrease in product quality indexes,which could be attributed to the increase in perovskite content in the finished sinter.展开更多
基金Project (50574101) supported by the National Natural Science Foundation of ChinaProject (2003UDBEA00C020) supported by the Collaborative Project of School and Province of Yunnan Province,China
文摘Sulfuric acid leaching process was applied to extract nickel from roasting-dissolving residue of a spent catalyst, the effect of different parameters on nickel extraction was investigated by leaching experiments, and the leaching kinetics of nickel was analyzed. The experimental results indicate that the effects of particle size and sulfuric acid concentration on the nickel extraction are remarkable; the effect of reaction temperature is mild; while the effect of stirring speed in the range of 400-1 200 r/min is negligible. Decreasing particle size or increasing sulfuric acid concentration and reaction temperature, the nickel extraction efficiency is improved. 93.5% of nickel in residue is extracted under suitable leaching conditions, including particle size （0.074-0.100） mm, sulfuric acid concentration 30% （mass fraction）, temperature 80 ~C, reaction time 180 min, mass ratio of liquid to solid 10 and stirring speed 800 r/min. The leaching kinetics analyses shows that the reaction rate of leaching process is controlled by diffusion through the product layer, and the calculated activation energy of 15.8 kJ/mol is characteristic for a diffusion controlled process.
基金financially supported by the National Natural Science Foundation of China (Nos.U2002212 and 52204412)the National Key R&D Program of China (Nos. 2019YFC1907101,2019YFC1907103 and 2021YFC1910504)+3 种基金Key R&D Program of Ningxia Hui Autonomous Region (No. 2020BCE01001)Guangdong Basic and Applied Basic Research Foundation (No.2020A1515110408)Foshan Science and Technology Innovation Special Foundation (No.BK21BE002)the Fundamental Research Funds for the Central Universities (No.FRF-TP20-031A1)。
文摘Production of petrochemical catalysts accounts for one of the largest shares of platinum group metals(PGMs) consumption;thus,recycling of spent petrochemical catalysts holds great economic value.Conventionally,PGMs are recovered through hydrometallurgical processes which have a low recovery efficiency and produce a large amount of waste.In this regard,this paper proposed a method to use iron-capturing PGMs based on CaO-Al_(2)O_(3)-Na_(2)O slag.This method avoided the formation of Fe-Si alloy and achieved efficient enrichment of PGMs.The droplet force model showed that the recovery efficiency of PGMs could be improved if the slag had low density and low viscosity.Based on this result,FactSage software optimized the composition of slag.Furthermore,the effect of B_(2)O_(3) on the 1400 ℃ liquidus of CaO-Al_(2)O_(3)-Na_(2)O_(3)-B_(2)O_(3) phase diagram was revealed.Moreover,it was found that the recovery efficiency of PGMs exceeded 99% under the following optimized conditions:basicity of 1.0,20 wt%Na_(2)O,15 wt% B_(2)O_(3),15 wt% Fe,3 wt% C and a temperature range of 1400-1500℃.The thermodynamic model revealed the mechanism of iron capture.Different chemical bonds prevented the formation of bonds between the alloy and slag,resulting in the separation of the slag from the alloy.PGMs particles and iron microspheres had significant surface Gibbs free energy.Only when iron microspheres and PGMs particles collided and fused with each other to reduce their surface area could the Gibbs free energy of the system be reduced.
基金Project(2008DFA91500)supported by the China International Science and Technology Cooperation ProgramProject(2006GH01)supported by the International Collaboration Project of Yunnan Provincial Science and Technology DepartmentProject(14051157)supported by Yunnan Provincial Natural Science Foundation
文摘A new technology for microwave pretreatment of spent catalyst on Zn extraction by HCl leaching was proposed and the temperature-change curve of spent catalyst under microwave irradiation was measured.The influence of microwave pretreatment temperature and microwave irradiation time on zinc extraction was investigated and the mechanism of microwave pretreatment for spent catalyst was analyzed.The results show that microwave pretreatment can greatly enhance the leaching rate of Zn.The Zn extraction reaches 96.58%under the conditions of microwave pretreatment temperature of 950℃and the microwave irradiation time of 12 min.The blocked pores of spent catalyst can be opened through microwave pretreatment,increasing the contact area of leaching reagent and zinc.
基金financially supported by the National Natural Science Foundation of China for Distinguished Young Scholar(No.52025042)。
文摘Hazardous wastes from the production of cleaner fuels,spent hydrodesulfurization(HDS)catalysts,pose a threat to the environment and the sustainability of rare metal resources.However,conventional recovery approaches are limited by long processes,easy generation of waste liquids,and difficult reuse of recovery products.Herein,a SiO_(2)-Na_(2)O-B_(2)O_(3)-MgO-TiO_(2)glass phase extraction system was proposed for the full-component recycle from spent MoNi/γ-Al_(2)O_(3)catalysts to the materials,including the individual recovery of Mo and the synthesis of Ni^(2+)-doped glass–ceramics.96.7%of Ni and 99.8%of Al were extracted into the loaded glass in one step,while 95.3%of Mo was precipitated as molybdate and directly recovered with high separation factors(SF_(Mo/Ni)594.8,SF_(Mo/Al)8718.2)in one step.Moreover,the broadband near-infrared luminescence(1150-1700 nm)of glass–ceramics was triggered by Ni^(2+)in the octahedral crystal structure of Me_(3)O_(5)(Me=Mg,Al,Ti)by meltingannealing-crystallization processes,which provided it the potential to be applied in tunable lasers and broadband optical amplifiers for the wavelength-division-multiplexing transmission systems.The Ni^(2+)-doping mechanism was calculated using molecular dynamics simulations.This work emphasized the maximization of the reuse value for each metal resource from hazardous wastes while reducing the burden on the environment and achieving the recycling of rare metal resources with re-valorization.
基金Funded by the Natural Science Foundation of Henan(No.252300421563)the Key Research Projects of Henan Provincial Colleges and Universities(No.25B450001)+3 种基金the Basic and Frontier Research Project of Nanyang(No.24JCQY032)National Natural Science Foundation of China(No.52201044)the Key Specialized Research&Development and Promotion Project(Scientific and Technological Project)of Henan Province(No.232102221022)the Basic and Frontier Technology Research Project of Nanyang(No.23JCQY1001)。
文摘This paper presented a novel and environmentally friendly approach for recovering platinum group metals(PGMs)from spent automotive exhaust catalysts.The study employed lead slag and waste graphite electrodes as raw materials,incorporating CaO as an additive to fine-tune the slag's viscosity and density.By reducing FeO in the lead slag using waste graphite electrodes,pure Fe was obtained,effectively trapping the PGMs from the exhausted catalysts.The study explored the effects of reductant addition,trapping duration,slag basicity,and trapping temperature on the recovery rate of PGMs.The results indicated that a maximum recovery rate of 97.86%was achieved when the reductant was added at 1.5 times the theoretical amount,with a trapping duration of 60 minutes,a slag basicity of 0.7,and a trapping temperature of 1600℃.This research offered a greener pathway for the recovery of PGMs from spent automotive exhaust catalysts.
文摘An attempt has been made to investigate and optimize the recovery of Ni and Al through sulphuric acid(3.0-5.5 mol/L)leaching under different operating conditions.From the leaching experiments,it was possible to extract 98.5%of NiO and 40.7%of Al_(2)O_(3)under the conditions of 5.5 mol/L H_(2)SO_(4),reaction time of 4 h,solid-to-liquid ratio 0.2 g/mL,temperature of 358 K,particle size<100μm,200-250 r/min with 5.0 g catalyst dosage.The leached liquor Al was separated by selective crystallization using 1.4 mol/L KOH and Ni was separated by selective precipitation using 0.3 mol/L H_(2)C_(2)O_(4).From the studies,it is possible to recover around 97.9%of NiO having 98.3%purity,around 25%of Al_(2)O_(3)was also recovered as alum-(K)having 99%purity and 14.7%of Al_(2)O_(3)as a salt of Al-K-C_(2)O_(4)-SO_(4).Sulphuric acid was found to be a suitable leaching agent for selective leaching and it was also observed that alum-(K)can be selectively crystallized from sulphate solutions.The study also indicated the effective extraction and recovery of nickel and aluminium which were well supported by characterization studies using TG-DTA/DTG and XRD techniques.
文摘Advanced technological achievements and the continuous growth of economy have made the disposal, recycle and reuse of industrial by-products a severe challenge. The cement industry is considered one of the key sectors in this effort in successfully （in terms of not extenuating but improving some of the properties of the final product） absorbing large quantities of solid wastes, either as aggregates or as secondary cementitious materials. This not only contributes to the creation of an energy and CO2-emission depository （as commonly used raw materials are spared）, but also simultaneously alleviates the acute environmental burden caused by the irresponsible disposal of such by-products. In this study, the possibility of reusing spent fluid catalytic-cracking catalyst （FCC） as a supplementary cementing material （SCM） was examined. A series of tests were conducted, initially aiming at characterizing the material and thereafter evaluating its pozzolanic activity and its effect on the mechanical properties of blended cements. Major findings in this investigation revealed that the use of FCC as a mineral admixture in cement is feasible, strengthening the belief that siliceous glassy residues should represent a steady supply for the construction sector.
基金Supported by the Key Research Program of Frontier Sciences of CAS(QYZDJ-SSWJSC021)the Science and Technology Cooperation for Yunnan Provinces and CAS(2016IB002)+1 种基金Science and Technology Service Network Initiative of CAS(KFJ-SW-STS-148)National Natural Science Foundation of China(21506233,51402303,21606241,51374191)
文摘Traditionally,Ag-containing solid wastes are leached by nitric acid in order to recycle the noble metal.However,the huge amounts of emission of toxic nitrogen oxides demand the development of a new method for silver recycling.Recently,considering the Ce(Ⅳ)solution could be regenerated with electrolyzation method,our group invented a novel environmentally friendly process by using Ce(Ⅳ)as the oxidant to dissolve silver from the spent Ag/ɑ-Al_2O_3 catalysts without NO_x emission.To find out the optimal parameters,in this work,the leaching reaction was thoroughly investigated with respect to the temperature,oxidant and HNO_3 concentrations,stirring speed,and time.The optimized leaching reaction gave the leaching silver rate 99.8% in 1 h.The kinetic plots suggested a shrinking core model with the internal diffusion-controlled process and the activation energy of 38.83 k J·mol^(-1).The order in which the experimental conditions influence the reaction was determined through orthogonal analysis:temperature N oxidant concentration N HNO_3 concentration N stirring speed.
基金provided by the National Natural Science Foundation of China(No.21371055)the Hunan provincial Natural Science Foundation of China(No.11JJ2008)the Hunan provincial Colleges and Universities Innovation Platform Open Fund Project(No.15K049)
文摘Novel composite material with a wide pore distribution was synthesized by an in situ technique using spent FCC catalyst as raw material. The characterization results indicated that the composite material contained 56.7% of zeolite Y and exhibited a much larger specific surface area and pore volume as well as strong hydrothermal stability. Fluid catalytic cracking(FCC) catalyst was prepared based on the composite material. The results indicated that the as-prepared catalyst possessed a unique pore structure that was advantageous to the diffusion-controlled reactions. In addition, the attrition resistance, activity and hydrothermal stability of the studied catalyst were superior to those of the reference catalyst. The catalyst also exhibited excellent nickel and vanadium passivation performance, strong bottoms upgrading selectivity, and better gasoline and coke selectivity. In comparison to the reference catalyst, the yields of the gasoline and light oil increased by 1.61 and 1.31 percentage points, respectively, and the coke yield decreased by 0.22 percentage points, and the olefin content in the produced gasoline reduced by 2.51 percentage points, with the research octane number increased by 0.7 unit.
基金Project(22178392)supported by the National Natural Science Foundation of China。
文摘Preparation of high purity ruthenium nitrosyl nitrate using spent Ru-Zn/ZrO_(2)catalyst was studied,including melting and leaching to obtain potassium ruthenate solution,reduction,dissolving,concentrating and drying to obtain ruthenium trichloride,nitrosation and hydrolysis to obtain ruthenium nitrosyl hydroxide,removing of K^(+)and Cl^(-),and neutralization with nitric acid.The effects of temperature,concentration,time and pH on the yield and purity of intermediates and final product were studied,and the optimum process conditions were obtained.The yield of ruthenium nitrosyl nitrate is 92%,the content of ruthenium in high purity product is 32.16%,and the content of Cl^(-)and K^(+)are much less than 0.005%.The reaction kinetics of ruthenium nitrosyl chloride to ruthenium nitrosyl hydroxide was studied.The reaction orders of Ru(NO)Cl_(3)at 40,55 and 70℃are 0.39,0.37 and 0.39,respectively,while those of KOH are 0.16,0.15 and 0.17,respectively.The activation energy is-2.33 k J/mol.
文摘Oxidation of coke deposited on spent catalytic cracking catalysts was compared with that of coal and coal char via the non-isothermal oxidation means,i.e.the thermal-gravimetric analysis(TGA)and the differential thermal analysis(DTA).Oxidation kinetic parameters were further investigated by model-fitting methods.The test results showed that the oxidation of spent catalysts was a quite mild process,while coal and coal char experienced sharp weight loss during oxidation.The temperature for commencement and termination of oxidation increased in the following order:coal〈coal char〈spent catalysts,and the oxidation of the three tested materials displayed a self-catalytic nature,with their largest oxidation rate appearing at a weight percent of 24.96%,34.21%and 57.93%,respectively.The oxidation of spent catalysts obeyed a random nucleation model for the first-order reaction,with Ea=206.13 kJ/mol and lgA=10.10,and the oxidation of coal could be a diffusion-controlled reaction mechanism,with Ea=161.61 kJ/mol and lgA=7.74,while the oxidation of coal char also obeyed a random nucleation model for the first-order reaction,with Ea=149.36 k J/mol and lgA=7.89.
基金financially supported by the High-degree Talent Introduction Program of Guangdong Academy of Sciences(No.2017GDASCX-0841)the Science and Technology Program of Guangzhou(No.201607020021)+2 种基金the National Natural Science Foundation of China(No.51304055)the Innovative Platform Construction Program of Guangdong Academy of Sciences(No.2017GDASCX-0109)the Pearl River Nova Program of Guangzhou(No.201806010016)
文摘The study of the leaching of vanadium(V) and molybdenum(Mo) from spent petrochemical catalysts in sodium hydroxide(NaO H) medium was performed using two approaches, namely, conventional leaching and microwave-assisted leaching methods. The influence of microwave power, leaching time, leaching temperature, and NaOH concentration on the leaching efficiency of spent petrochemical catalyst was investigated. Under microwave-assisted conditions(600 W, 10 min, 90°C, 2.0 mol·L^(-1) NaOH, and 0.20 g·mL^(-1) solid–liquid ratio), the leaching efficiencies of V and Mo reached 94.35% and 96.23%, respectively. It has been confirmed that microwave energy has considerable potential to enhance the efficiency of the leaching process and reduce the leaching time. It is suggested that the enhancement of the leaching efficiencies of V and Mo can be attributed to the existence of a thermal gradient between solid and liquid and the generation of cracks on the mineral surface.
基金financially supported by the National Natural Science Commission-Yunnan Joint Fund Project (No.U1402274)
文摘Aluminum recovery is a key issue for the overall recycling of valuable metals from spent catalysts. This paper focuses on the recovery and regeneration of alumina with high additional value from the spent hydrodesulfurization catalyst CoMo/Al_2O_3. The results indicate that 98.13% alumina is successfully leached from the treated spent catalysts by an alkaline leaching process under the conditions of 5 mol·L^(-1) sodium hydroxide,a liquid/solid ratio of 20 ml·g^(-1),a temperature of 160 0 C and a reaction time of 4 h. In the leaching residue, no difficult leaching compound is found and cobalt and nickel are enriched,both of which are conducive to the subsequent metal recovery step. The reaction order of aluminum leaching is 0.99. This reaction fits well with the interfacial chemical reaction model, and its apparent activation energy is calculated as 45.50 kJ mol^(-1). Subsequently, y-Al_2O_3 with a high specific surface area of 278.3 m^2·g^(-1), a mean size of 2.2 μm and an average pore size of 3.10 nm is then regenerated from the lixivium, indicating its suitability for use as a catalyst carrier. The recovery and regeneration of alumina from spent catalysts can not only significantly contribute to the total recycling of such hazardous spent catalysts but also provide a new approach for the preparation of y-Al_2O_3 with a high specific surface area using spent catalysts as the aluminum sources.
基金the National Natural Science Foundation of China(Grant No.51804277)supported by the State Key Laboratory of Special Rare Metal Materials(No.SKL2020K004)+1 种基金Northwest Rare Metal Materials Research Institutesupported by the State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization(No.CNMRCUKF2008)。
文摘Spent catalyst used for denitration by selective catalytic reduction(spent SCR denitration catalysts) is one of the important urban mines due to the high content of TiO_(2)(~85 wt%) and the massive accumulation amount(over 100,000 tons),therefore,value-added reutilization of titanium in spent SCR catalysts is considerably meaningful.In this paper,a novel method is proposed for converting the titanium oxide in spent SCR denitration catalysts to metallic titanium.Specifically,titanium dioxide(TiO_(2)) was firstly obtained from spent SCR denitration catalysts after removing the impurities by hydrometallurgy process.Then,TiO_(2) is converted to Ti_(2)CO by carbothermic reduction method,and Ti_(2)CO was further purified by oleic acid capture.Finally,by utilizing the as-prepared Ti_(2)CO as the consumable anode in the NaCl-KCl molten salt,high-purity metallic titanium was deposited at cathode,all confirming the feasibility for the conversion of low-grade TiO_(2) in the spent catalysts,from 60 wt% to high-purity metallic Ti(99.5 wt%), furthermore,the energy consumption of this process is 3950 kWh tonne-1 Ti,which is lower than that of most traditional titanium metallurgy methods.The method herein can provide new insights for the value-added recycling of titanium resources in urban mines.
基金The authors are grateful for the financial support of the National Natural Science Foundation of China(No.51574214).
文摘The selective dissolution of V and Fe from spent denitrification catalyst(SDC)with oxalic acid was investigated to minimise their environmental effects.The dissolution kinetics of different elements from SDC by using 0.1–1.5 mol L^(-1) oxalic acid concentration was studied at 60℃–90℃.V and Fe were preferentially released(65%and 81%)compared with Al,Ti and W within 5 min due to the redox reactions of oxalic acid.The dissolved fractions of Fe,V,Al,Wand Ti increased with the increase of oxalic acid concentration and reaction temperature.The dissolution kinetic experiments were analysed and controlled diffusion with n<0.5 according to the Avrami dissolve reaction model(R^(2)>0.92).The Arrhenius parameters of the Ea values of Ti,W,V,Fe and Al from SDC with oxalic acid were 30,26,20,19 and 11 kJ mol^(-1),respectively.The obtained Avrami equation of V and Fe was successfully used to predict their leaching behaviour in oxalic acid.Toxicity characteristic leaching procedure revealed that the toxicity risk of Vand Fe metals from SDC after leaching with oxalic acid decreased to below 5 mg kg^(-1) residua.Overall,the leaching residua by oxalic acid indicated its safety for the environment.
基金financially supported by the National Key Research and Development Program for Young Scientists,China(No.2021YFC2901100)。
文摘Platinum group metals(PGMs),especially Pd,Pt,and Rh,have drawn great attention due to their unique features.Direct separation of Pd and Pt from highly acidic automobile catalyst leach liquors is disturbed by various factors.This work investigates the effect of various parameters including the acidity,extractant concentration,phase ratio A/O,and diluents on the Pd and Pt extraction and their stripping behaviors.The results show that the Pd and Pt are successfully separated from simulated leach liquor of spent automobile catalysts with monothioCyanex 272 and trioctylamine(TOA).Monothio-Cyanex 272 shows strong extractability and specific selectivity for Pd,and only one single stage is needed to recover more than 99.9% of Pd,leaving behind all the Pt,Rh,and base metals of Fe,Mg,Ce,Ni,Cu,and Co in the raffinate.The loaded Pd is efficiently stripped by acidic thiourea solutions.TOA shows strong extractability for Pt and Fe at acidity of 6 mol·L^(–1) HCl.More than 99.9% of Pt and all of the Fe are extracted into the organic phase after two stages of countercurrent extraction.Diluted HCl easily scrubs the loaded base metals(Fe,Cu,and Co).The loaded Pt is efficiently stripped by 1.0 mol·L^(–1) thiourea and 0.05–0.1 mol·L^(–1) Na OH solutions.Monothio-Cyanex 272 and TOA can realize the separation of Pd and Pt from highly acidic leach liquor of spent automobile catalysts.
基金financially supported by the Natural Science Foundation of Anhui Province(No.2108085J26)the National Natural Science Foundation of China(Nos.51904003 and U1703130)+1 种基金the Key Research and Development Plan of Anhui Province(No.2022n07020004)the Open Foundation of State Key Laboratory of Complex Nonferrous Metal Resources Clean Utilization(No.CNMRCUKF2208)。
文摘Platinum(Pt)is a critical raw material for automotive catalytic converters due to its high-temperature stability,corrosion resistance and catalytic activity,whereas its limited primary resources and uneven distribution make it hard to meet the growing demand of platinum.Spent automotive catalyst(SAC)is currently the most important secondary resource of platinum,of which the platinum content is much higher than that of the primary platinum resources.The recovery process of platinum from spent automobile catalyst mainly consists of pretreatment followed by enrichment and refining,involving pyro-and hydrometallurgical techniques,among which enrichment and refining processes are extremely important for platinum recovery from spent automobile catalyst.This paper provides an overview of the technologies for platinum recovery from spent automotive catalyst.The emphasis is placed on the processes of enrichment and refining based on hydrometallurgical techniques.Future directions of research and development of platinum recovery from spent automobile catalyst are also proposed.
基金the funding provided by the Fujian Provincial Education Department Project(JA09054)the Project administered by the Fujian Normal University(XG-004)+4 种基金the Fujian Provincial Eco- nomic and Trade Commission Project(HE0536)the Open Project of the MOE's Key Laboratory for Medical and Photoelectrical Science and Technology(JYG0821)the Open Project of Hubei Province,the State Nationalities Committee,and the MOE Joint Key Laboratory for Catalytic Material Science(CHCL08008)the Fujian Provincial Testing Fund Project for the Key Laboratory of Highmolecular Materials(FJKL-POLY2010-17)the Training for Excellence Youth Skeleton Teacher of Fujian Normal University(No.2008100228).
文摘The chemical composition, structure and thermal stability of the spent FCC equilibrium catalyst from an oil refinery were characterized by XRD, FT-IR, DTA-TG, BET, complete chemical analysis, SEM, and XRF. The spent FCC equilibrium catalyst, clay, barium carbonate, and talc were used as the main raw materials to prepare the alumina abrasion-resistant ceramic balls to be used in the powder grinding mill for manufacture of architecture tiles. The results showed that after proper formulation study, the spent FCC equilibrium catalyst could replace industrial alumina to prepare high performance grinding balls. Meanwhile, the various performance indices of the grinding ball could meet the quality standard for similar products, and additionally, the energy saving effect was achieved in the operation of the grinding section, resulting in a successful comprehensive utilization of solid wastes.
基金financially supported by the National Natural Science Foundation of China(Nos.U2002212,52204412 and 52102058)the National Key R&D Program of China(Nos.2019YFC1907101,2019YFC1907103 and 2021YFC1910504)+3 种基金the Key R&D Program of Ningxia Hui Autonomous Region(No.2021BEG01003)Guangdong Basic and Applied Basic Research Foundation(No.2020A1515110408)Foshan Science and Technology Innovation Special Foundation(No.BK21BE002)the Fundamental Research Funds for the Central Universities(Nos.FRFTP-20-031A1 and FRF-BD-20-24A)。
文摘Spent hydrogenation catalysts are important secondary resources due to richness in the valuable metals of Ni,Mo and V.Recovery of valuable metals from spent catalysts has high economic value and environmental benefits since they are hazardous wastes as well.Traditional recycling processes including hydrometallurgical leaching and soda roasting-leaching have disadvantages such as generating large amounts of wastewater,long process,and low recovery efficiency of valuable metals.Thus,this paper proposed synergistic enrichment of Ni,Mo and V via pyrometallurgical reduction at 1400-1500℃.The melting temperature and viscosity of slag were reduced through slag designing by software FactSage 7.1.The phase diagram of Al_(2)O_(3)-Cap-SiO_(2)-Na_(2)O-B_(2)O_(3)was drawn,and low-temperature region(≤1300℃)was selected as target slag composition.Ni,Mo,and V can be collaborative captured and recovered through the mutual solubility at molten state.Increasing the melting temperature and the amount of CaO,Na_(2)O and C were conducive to improving the metals recovery rates.The kilogram-scale experiments were carried out,and the recovery efficiencies of Ni,Mo and V were 98.3%,95.3%and 97.9%under optimized conditions:at 1500℃,with the basicity of 1.0,13.1 wt%SiO_(2),7.0 wt%B_(2)O_(3),7.7 wt%Na_(2)O and 20.0wt%C.The distribution behavior of valuable metals was clarified by investigating the melting process of slag and the reduction in valuable metals.Ni was preferentially reduced and acted as a capturing agent,which captured other metals to form NiMoV alloys.
基金suppored by the National Natural Science Foundation_of China(52174290 and 51704009)the University Synergy Innovation Program of Anhui Province(GXXT-2020-072).
文摘A large number of spent selective catalytic reduction(SCR)denitration catalysts are produced after the ultra-low emission transformation of coal-fired power plants in China.According to the China’s“Directory of National Hazardous Wastes(Version 2021)”,these spent vanadium-tungsten-titanium catalysts are classified as“HW50”hazardous waste,and their disposal and utilization processes have been strictly controlled.Thus,an effective and low-cost technique was developed to treat and utilize these spent SCR catalysts by the vanadium-titanium magnetite sintering process.Effects of adding spent SCR catalysts on the sintering production process and product quality indexes of sinter were studied.The results showed that adding spent SCR catalysts can improve the sintering granulation and green feed permeability,thereby increasing the productivity and flame front speed.When the addition proportion of spent SCR catalysts is less than 1 wt.%,the performance indexes of the finished sinter are basically equal to those of the finished sinter without adding spent SCR catalysts.Further increasing the proportion of spent SCR catalysts to 2.0 wt.%results in a decrease in product quality indexes,which could be attributed to the increase in perovskite content in the finished sinter.
