Study On The Respective Recovery Of Zinc, Nickel,Cobalt In Zinc Residue From Zinc Hydrometallurgy

At present, with the rapid development of economy, the demand of our country in zinc,nickel, cobalt and other heavy metal resources is increasing, however, as a non-renewablemineral resources, its formation needs millions of years, or even longer. Therefore,it isimperative to secondary recycle of the waste residue which produced by smelting,electroplating and other industries. Recycling of metal from waste residue, not only can easethe contradiction of the development of the national economy to metal demand growing, butalso protect environment, follow the necessary road of sustainable development.The raw material of this experiment is from Zinc Hydrometallurgy of some NorthwestSmelter.As the waste residue contains high zinc, nickel,cobalt and other valuable metals, hasan extremely high recovery value,therefore,subject determined by the wet process of leachingagent leaching purification and separation electrowinning recycling to recover the threemetals of zinc, nickel and cobalt.The first part of the experiment is the stage of leaching agent leaching. In this stage,through a series of waste residue leaching tests to determine the waste residue of onceoptimum leaching conditions are: leaching agent for sulfuric acid,leaching agentconcentration0.5mol/L,liquid-solid ratio10:1, extraction time1h, the leaching temperaturebeing25℃.In this condition, the the slag leaching rate reaches92.22%, and the leachingeffect ideal. By secondary leaching tests found, by the time the leach residue after againleaching, the leaching rate was only0.02%. Therefore, we confirmed, it is suitable for wasteresidue to leach once by sulfuric acid.The subject of the second part is separation and purification stage.At this stage, accordingto the zinc replacement test,the selective leaching test and the extraction and back-extractiontest,we have a successful separation of zinc, nickel and cobalt, lay the foundation for thefollowing three kinds of metal are respectively and electrically product recovery.The zincpowder repalcement test determined the alloy zinc powder method replacement nickel, cobaltis more appropriate,.The parameters were: Zn dosage of12.50g/L, temperature85℃, time90min, pH4.5. Selective leaching test determined the pH value of3.5to the process, the pHvalue of4.0to the end, the leaching effect is the best, the leaching of zinc, nickel, cobalt wasrespectively96.15%,8.72%and8.53%, the acid consumption was76.92%. Finally, by theextraction and back extraction test, we obtained relatively pure electrolyte solution whichrespectively contain zinc, nickel, and cobalt.The last part of the subject is the stage of electrowinning recovery.At this stage,the testuses membrane electrowinning to recover zinc, nickel, and cobalt,determined with the singleanion exchange membrane electrowinning to recover zinc,with the single cation exchange membrane electrowinning to recover nickel, with the double membrane three-compartmentelectrowinning to recover cobalt. Finally, the results show that under the recovery conditionswe set, the recovery effect of zinc, nickel and cobalt is obvious,91%zinc,98.92%nickel and88.16%cobalt can be available at a higher current efficiency.Finally, we have a preliminary estimate of the economic benefits of the whole issue, theanalysis shows: according to the process of lixiviant leaching-separation purification-electrowinning recovery, zinc, nickel and cobalt which in waste residue can be recoveredsuccessfully. Not only to protect the environment, to avoid heavy metal pollution, and canproduce more than1,500yuan per ton of waste residue, which achieved a win-win situation toprotect the environment and improve economic efficiency.