Recovery Of Zinc From Raffinate After Copper Extraction

After the process of high sulfur gold concentrate roasting-leaching in gold smelting plants,the raffinate contains more Zn2+,and there is no effective zinc recovery and utilization process at present,which wastes precious resources.To solve the problems of low zinc concentration and high content of iron,arsenic,and other impurities,this paper studied the process of "pre-neutralization-subsection vulcanization’ to recover zinc by forming ZnS concentrate.Besides,the plant’s cyanide barren solution of acid precipitation slag(AVR-S)contains the more valuable elements such as copper,zinc,this paper adopted "sulfide transfer-roasting-hot acid leaching" process,removed the sulfur cyanide ion and cyanide ion from precipitation,reduced N content,and produced precipitation returned boiling roaster.Under the premise of no additional equipment investment,copper and zinc resource recycled,the process method further improves the resource utilization,and increases plant economic benefits.In this paper,the study of sulfide precipitation in raffinate was carried out,and the trend and influence rule of each element in the process of pre-neutralization,purification and vulcanization were verified,and the process parameters of each step were investigated.The study results showed that the recovery of Zn was 96.56%and the grade of Zn was 52.32%under the process parameters of sodium sulfide excess coefficient 1.3,pH value of sulfide 3.0,precipitation temperature 25℃ and precipitation time 30 min.After removing the impurity elements As and Cu by pretreatment,the recovery of Zn was 95.72%and the grade of Zn was 54.08%.In this paper,the technology of "sulfide transfer-roasting-hot acid leaching" of cyanide barren solution of acid precipitation slag was studied,and the influence rules of different factors on AVR-S transfer,roasting and hot acid leaching were verified,and then the process parameters were optimized to realize the recovery of valuable metal elements such as Cu and Zn in AVR-S.The results showed that at the liquid-solid ratio of 2:1,pH value of 10,the excess coefficient of sodium sulfide of 1,and precipitation time of 60 min,the N content in the transfer precipitation is 0.836%.Under the roasting temperature of 600℃,roasting time of 120 min,the liquid-solid ratio of 8:1,the sulfuric acid concentration of 150 g·L-1,and leaching temperature of 60℃,the leaching rate of Cu was 94.57%and the leaching rate of Zn was 84.67%.