Research On Comprehensive Recovery Process Of Gold And Silver Materials In Lead Copper Metallurgy

With the pressure coming from continuous consumption of rare metal resources and environmental pollution,the recycle of materials containing gold and silver is becoming particularly important.In this paper,vacuum metallurgical method,which has advantages of short process,low pollution,high metal recovery,was adapted to do vacuum distillation experiments on materials containing gold and silver during the smelting of lead and copper.This method is of high convenience,low consumption and high efficiency to recover scare metal of selenium and tellurium,gold and silver and precious metal such as lead,antimony and bismuth metal.The thermodynamics analysis of the feasibility of vacuum distillation on gold and silver materials was conducted.The results show that Cu,Au and Ag were enriched in the residue under the condition of vacuum.Se,Te and S were volatilized into gas phase.The decrease in system pressure was good for vacuum pyrolysis reaction.Pb,Cu and Pb-Ag binary alloy separation factor was more than 1,Pb was volatilized into gas phase in the process of distillation,Cu and Ag residues in the liquid phase.The T-x(y)phase diagram shows that low voltage had a positive effect on vacuum distillation separation of alloy.The finding above can help us choose ingredients needed for vacuum distillation in the optimal experimental conditions according to the product,it can also help predict a certain temperature under the condition of residues and the amount of volatile matter according to the lever rule.The P-x(y)phase diagram shows that product composition was changing with the distillation temperature and pressure in the process of vacuum distillation.Moreover,the product ingredients can be quantitatively predicted based on the distillation temperature and system pressure.The level of small and hundred kilo experiments of vacuum distillation of copper dross were carried out.Small experiments show that:The contents of Pb,Cu and Ag in the volatiles were 83.86%,1.66%and 26 g/t,respectively.When the distillation temperature and time respectively set at 900? and 30 min,the corresponding content of Pb,Cu,S,and Ag in the residue were 2%,47.74%,0.04%and 3044.50 g/t.The results of hundred kg test show that:Copper and silver alloy was obtained under the condition of 200 kg feedstock,20-160 pa,1250?,4.5 h.The contents of Pb,Cu,Ag,Sb and S were 0.46%,57.38%,3919.21 g/t,24.41%and 0.21%.The primary condensate was sulphur and lead alloy,including 10%S and 83.74%Pb respectively.The secondary condensate was crude lead containing 87.55%Pb and 1.17%Cu.The vacuum distillation experiments of melting alloy tailings were conducted in distillation temperature of 550-1050?,and the results show that the optimal recovery distillation temperature and time of scarce metal selenium and tellurium were 750? and 120 min.Under this condition,the removal rates of Se and Te were 98.09%and 97.82%respectively,and the content of residue Se and Te were 0.083%and 0.3%respectively.The optimal distillation temperature and time of recycling gold and silver from rare metals were 1000? and 50 min,respectively.In addition,the volatile matter content of Au and Ag was only 0.5 g/t and 27 g/t.the Pb,Sb and Bi content of residue was 0.083%,0.3%and 0.41%respectively.It is worth noting that the direct recovery of Au and Ag was greater than 99.2%.