Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical he...Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated.The leaching behavior of Cr under different conditions is studied in detail.Acid leaching-selective oxidation-coprecipitation method is proposed based on the characteristics of Cr in CGS.The detoxification of Cr in CGS is realized,and the detoxification mechanism is clarified.Results show that Cr is highly enriched in CGS.The speciation of Cr is mainly residual fraction(74.47%-86.12%),which is combined with amorphous aluminosilicate.Cr^(3+)and Cr^(6+)account for 90.93%-94.82%and 5.18%-9.07%of total Cr,respectively.High acid concentration and high liquid-solid ratio are beneficial to destroy the lattice structure of amorphous aluminosilicate,thus improving the leaching efficiency of Cr,which can reach 97.93%under the optimal conditions.Acid leaching-selective oxidation-coprecipitation method can realize the detoxification of Cr in CGS.Under the optimal conditions,the removal rates of Fe^(3+)and Cr^(3+)in the leaching solution are 80.99%-84.79%and 70.58%-71.69%,respectively,while the loss rate of Al^(3+)is only 1.10%-3.35%.Detoxification slag exists in the form of Fe-Cr coprecipitation(Fe_(1-x)Cr_xOOH),which can be used for smelting.The detoxification acid leaching solution can be used to prepare inorganic polymer composite coagulant poly-aluminum chloride(PAC).This study can provide theoretical and data guidance for detoxification of heavy metal Cr in CGS and achieve resource utilization of coal gasification solid waste.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
基金finally supported by the National Natural Science Foundation of China(52174390,U1810205)Innovation Academy for Green Manufacture of the Chinese Academy of Sciences China(IAGM2022D04)Strategic Priority Research Program of the Chinese Academy of Sciences China(XDA21040601)。
文摘Coal gasification slag(CGS)is a type of solid waste produced during coal gasification,in which heavy metals severely restrict its resource utilization.In this work,the mineral occurrence and distribution of typical heavy metal Cr in CGS is investigated.The leaching behavior of Cr under different conditions is studied in detail.Acid leaching-selective oxidation-coprecipitation method is proposed based on the characteristics of Cr in CGS.The detoxification of Cr in CGS is realized,and the detoxification mechanism is clarified.Results show that Cr is highly enriched in CGS.The speciation of Cr is mainly residual fraction(74.47%-86.12%),which is combined with amorphous aluminosilicate.Cr^(3+)and Cr^(6+)account for 90.93%-94.82%and 5.18%-9.07%of total Cr,respectively.High acid concentration and high liquid-solid ratio are beneficial to destroy the lattice structure of amorphous aluminosilicate,thus improving the leaching efficiency of Cr,which can reach 97.93%under the optimal conditions.Acid leaching-selective oxidation-coprecipitation method can realize the detoxification of Cr in CGS.Under the optimal conditions,the removal rates of Fe^(3+)and Cr^(3+)in the leaching solution are 80.99%-84.79%and 70.58%-71.69%,respectively,while the loss rate of Al^(3+)is only 1.10%-3.35%.Detoxification slag exists in the form of Fe-Cr coprecipitation(Fe_(1-x)Cr_xOOH),which can be used for smelting.The detoxification acid leaching solution can be used to prepare inorganic polymer composite coagulant poly-aluminum chloride(PAC).This study can provide theoretical and data guidance for detoxification of heavy metal Cr in CGS and achieve resource utilization of coal gasification solid waste.
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.
