Sulfuric Acid Roasting Of High Arsenic Copper Dust - Water Leaching To Separate Arsenic From Copper And Zin

Copper smelting process produces a large amount of dust,which contains copper,lead,zinc,tin,indium and other valuable metals with high economic value;however,the dust also contains arsenic,which is harmful to the environment,so its"green"resource utilization is of great practical significance.Current research shows that the efficient separation of valuable metals from arsenic-containing copper smelting soot and the harmless treatment of arsenic are the keys to the"green"treatment of high arsenic copper dust.For the high arsenic copper dust produced by a copper pyrometallurgica l smelting,this thesis adopts the"sulfation roasting-water leaching"process to separate arsenic and comprehensive recovery of copper and zinc,the main research contents and results are as follows:1.A systematic study on the mechanism of arsenic volatilization from copper smelting dust roasting was carried out,and the addition of sulfuric acid to remove arsenic on the basis of traditional reduction roasting was proposed.Combined with chemical composition analysis,physical phase analysis and differential thermal differential gravimetric analysis,the complexity of the composition in copper smelting dust was revealed,and the physical phase change pattern of arsenic during the volatilization process was explored,showing that arsenate is the main reason for limiting arsenic volatilization,such as Pb₃（AsO₄）₂ and Zn₃（AsO₄）₂ in the dust.In order to achieve efficient separation process of arsenic and other valuable metals at low temperatures to reduce energy consumption and save energy,it is necessary to introduce additives to decompose arsenates such as Pb₃（AsO₄）₂ and Zn₃（AsO₄）₂ to transform them to volatile arsenic phases,so it is proposed to add concentrated sulfuric acid to the smelting dust of conventional reduction roasted of high arsenic copper,and use its strong oxidizing properties and strong acidity to promote the decomposition of complex arsenic coexistence Pb₃（AsO₄）₂ and Zn₃（AsO₄）₂ phases in the roasting process and release arsenic in the form of As₂O₃to realize the volatilization of arsenic in high arsenic copper dust.Also based on the reducing property of the anthracite coal,As₂O₅ in the dust will be converted to As₂O₃ for volatilization at low temperature.Thermodynamic calculations and analysis confirmed that the reaction of arsenic removal from high arsenic copper smelting dust is feasible by adding anthracite coal and concentrated sulfuric acid at temperatures between 350°C and 400°C.2.The optimized conditions are obtained by experimental study as follows:sulfuric acid addition 0.3 m L/g,anthracite addition 10%,time 3 hours and temperature 350°C.under which the arsenic removal rate is>94.73%and the selective separation of arsenic from high arsenic copper dust can be achieved.3.The optimal water leaching conditions are found by experimental study:roasting temperature 350℃,sulfuric acid addition 0.3 m L/g,anthracite addition10%,roasting time 3 h,leaching temperature 85℃,stirring rate 400 r/min,solid-liquid ratio 1:4,leaching time 90 min,under these conditions,the leaching rate of copper and zinc are 94.5%and 99.94%respectively.The results of XRD and other investigations of the leaching residue show that almost all copper and zinc have been dissolved into the solution,and the main substances in the leaching residue are lead and bismuth compounds,and the selective separation of copper,zinc and lead,bismuth have been achieved.