| A new hydrometallurgical process without ferric residue was proposed for treating zinc sulfide concentrate bearing indium from Dachang in Guangxi. Adopting this new process, the recovery ratios of indium and zinc increased greatly. At the same time, this process can also prevent the environmental pollution of ferric residue because of the cancellation of process removing iron. Iron in the zinc sulfide concentrate was used to produce high valuable soft magnetic ferrite materials dierctly. In this paper, the technologies and the theories of the main stages in the new process have been investigated, which is of great significance to the maturity of this new process and its practical application.The first kinetics of leaching the residues from the neutral leaching process of zinc calcine with sulphuric acid of high concentration at high temperature was investigated for examining the effects of reaction temperature, concentration of reagents, the residue granule size, agitation rate and concentration of metal ions on the leaching process. The results show that the leaching process can be simulated with a shrinking core model. Because the residue contains of not only zinc ferrite, but also zinc oxide and other zinc species, the leaching process is composed of three stages distinguished by the leaching time. During the first stage ( 15min),leaching is very fast for solving ZnSO4(s) and part of ZnO. During the second stage (15~60min), zinc oxide and other zinc species are soluted chiefly with the of 51.792KJ/mol. The leaching rate is controlled by the surface chemical reaction .The reaction progression of H+,Zn2+and Fe3+ is 1.0771,-1.764 and -1.391,respectively. While in the third stage (60~300min), zinc ferrite and zinc sulfide were mainly leached out slowly with the activation energy of 20.72KJ/mol, The leaching rate is controlled by the mixed surface chemical reaction and outside diffiision,the reaction progression of H+,Zn2+and Fe3+ is 0.3993, -0.3767,and -0.4456, respectively.On the other hand, The reductive leaching the residue from neutral leaching by using zinc sulfide concentrate as reductive agent has been experimented, to be followed by the oxidative leaching by using pyrolusite as oxidation agent and manganese source. The optimum conditions of the reductive leaching with the scale of 400 g/time are following: the amount of zinc sulfide concentrate to be 1.03 times of the theoretical amount by addition in four batches, temperature of 368K, time of 5 hours, and the begot acidic concentration being 225 g/L. That of the oxidative leaching with the scale of 100 g/time are as: the amount of pyrolusite being 25 g/time, the begot acidic concentration to be more than or equal to 250 g/L, temperature of 368K, and time of 5 hours. Under the optimum conditions, the recovery ratios of indium, zinc and iron were96%, 96.25%, and 86% respectively. The reductive ratio of ferric ions is more than 93%. The results obtained from the experiments of the reduction by iron powder and removing copper show that the removing ratio of copper is 94.61%, the content of copper concentrate produced is higher than 74.20% .At last, the extraction to recover indium was researched in detail. Under the optimum conditions such as the componnent of the organic phase being D2EHPA of 30% and kerosene 70%, extraction temperature of 298K, progressions of 3, ratio of O/A to be 3:1, and extraction time being 5 min, the extractive ratio of indium and its stripping ratio are 99% and 99% respectively. By using zinc plate to cement indium, the displament ratio is 99% . The total recovery ratio of indium is 95%, from zinc calcline to spongy indium, which increased by 25% compared to the routine process.
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