Study On Selective Leaching Of Arsenic And Antimony From Copper Anode Slime

In the process of recovering valuable metals from copper anode slime,As and Sb could affect the recovery of rare and precious metals(RPM)and pollut the environment,it is necessary to give priority to the removal of arsenic and antimony.Using H2SO4+HCl+NaCl system to seletive leach As and Sb is conducive to RPM recovery.The behavior of the main metals in the acidic system was analyzed with E-ph diagram.Sb leaching demands high concentration of H+and Cl-,Cu,Ni,As,and Bi would disolve before Sb,Se,Ag and Pb would remain in residue.XRD of anode slime shows that As and Sb mostly exist in the form of trivalent oxide,which is beneficial to leaching.Effects of sulfuric acid concentration,hydrochloric acid concentration,NaCl concentration,leaching time,liquid-solid ratio and temperature on leaching ratios of As and Sb in copper anode slime were investigated through single factor experiments.The better technological conditions were sulfuric acid 2mol/L,hydrochloric acid 2mol/L,NaCl concentration 150g/L,leaching time 2h,liquid-solid ratio 4,leaching temperature 85?.Under the better technological conditions,leaching ratio of As and Sb were 99.58%and 80.83%,respectively.Almost all the Se and Ag remain in the residue.Effects of XA(sulfuric acid concentration,mol/L),XB(hydrochloric acid concentration,mol/L),and Xc(reaction temperature,?)were confirmed as process variables,Y1(As leaching ratio,%)and Y2(Sb leaching ratio,%)as response indicators were investigated,two order polynomial equations of model on leaching ratio of As and Sb leaching ratio were obtained as follows:Y1=99.48+0.67XA+0.68XB+0.30XC-0.15XAXB+0.069XAXC-0.31XBXC-0.52XA2-0.50XB2-0.18XC2Y2=78.75+6.33XA+6.11XB+3.32XC-2.48XAXB-1.78XAXC-1.24XBXC-2.00XA2-1.68XB2+0.17XC2The experiments conditions were optimized using response surface methodology(RSM)based on central composite design(CCD).The optimal technological conditions obtained by RSM were determined to be sulfuric acid concentration of 2.8mol/L,hydrochloric acid concentration of 1.0mol/L,and reaction temperature of 90?.Under the optimized conditions,the response values of the As and Sb leaching ratio were 99.10%and 80.00%,the observed As and Sb leaching ratio were 99.60%and 80.07%.The deviation between the experimental results and simulation results is little,indicating that the selected model has good predictive performance.