Study On A Hydrometallurgical Process For Zinc Recovery From Zinc Leaching Residue

In the hydrometallurgical zinc process,the zinc leaching residue is produced from the complex process of neutral-acid leaching or two-acid leaching of zinc sulfide or oxide ores.Due to containing lots of valuable metals such as zinc,lead,silver and gold,zinc leaching residue poses a serious threat to the environment for human survival.Zinc leaching residue can be used for secondary resources to deal with.Research and develop new processing technology of zinc leaching residue can be achieved double benefits for environment and economy.In this work,the experiments of leaching and deironing and extraction are studied according to the high-iron characteristics of zinc leaching residue provided form a hydrometallurgical corporation in Shandong.The sulfated roasting mechanism was studied through the thermodynamic analysis,and a new process of sulfated roasting-leaching and deironing and solvent extraction is presented.The leaching experiments of zinc residue are showed that the zinc reaching rate is only 43%,using direct sulfuric acid leach and sulfated roasting-leaching can reach zinc leaching rate of 85%.The parameters of roasting time and temperature,the dosage of sulfuric acid and leaching time have an influence on reaching rate.In the process of leaching solution deironing,comparing the methods and according to characteristics of zinc leaching residue,an oxidation-neutralization process is applied.The deironing theory of oxidation-neutralization is studied and the effects of O2,H2O2 and MnO2 for deironing rate.H2O2 is as the best antioxidant.the dosage of hydrogen peroxide solution is for the theoretical value of 1.8 times and addpartially,pH=5.2?5.4,oxidation reaction time 1.5h,reaction temperature 90?,the deironing rate can reach up to 99.35%.The extraction,washing and re-extraction experiments of purified liquid were studied in the solvent extraction process.At the condition of P204 concentration 30%,O/A=1,pH=2.00,zinc extraction rate is 50%.In order to increase the extraction rate,the extraction series is investigated and series 3 is determined for extraction rate 80%.In the zinc extraction process,impurity and co-exist metal ion is consisted in loaded organic phase,through the washing and re-extraction process,qualified zinc sulfate solution can be prepared.