Process And Principle Studies On Extracting Indium And Preparing Valuable Ferrite Materials Without Residue Emission In Zinc Hydrometallurgy For Treating Zn-In Concentrate Bearing High Iron

With the combination of zinc hydrometallurgy and directed co-precipitation method for preparing of Mn-Zn soft magnetic ferrite materials, a new clean process for hydrometallurgically extracting zinc, indium without ferrite residue emission and directly preparing Mn-Zn soft magnetic ferrite was developed in this dissertation. The ferrite resource in zinc concentrate got value-added utilization and the emission of ferrite residue and sulfur dioxide was avoided simultaneously. It's not only a great progress in hydrometallurgical extracting of zinc and indium, but also a first attempt to directly prepare Mn-Zn soft magnetic ferrite from ferrite resources in zinc ores. Using neutral leaching residue as raw material, systemic studies on the reductive and oxidative hot leaching with high concentration acid, solvent extraction of indium with D2EHPA, sulphide precipitation for primary purification, complex salt precipitation for deep purification, redundant zinc removing, complex salt transformation and ammonia leaching, producing zinc powder by electrowinning or recoverying zinc by vaporizing, Mn-Zn soft magnetic ferrite process and (NH₄)₂SO₄ recovery were carried out in this dissertation. And some meaningful conclusions were obtained.The kinetics on the hot leaching of neutral residue with high concentration acid was investigated. The results showed the leaching reactions followed the shrinking core model. The leaching process was consisted of the following three stages distinguished by the leaching time. During the first stage (t≤15min), ZnSO₄ dissolved in the solution and the leaching rate was very fast. During the second stage (15～60min), zinc oxide and other zinc dissoluble species dissolved chiefly, the apparent activation energy was 51.792kJ/mol. The leaching rate was controlled by the chemical reaction. While in the third stage (60～300min), zinc ferrite and zinc sulfide were mainly leached out slowly, the apparent activation energy was 20.72kJ/mol. The leaching reaction was simultaneously controlled by the chemical reaction and extemal diffusion. The following expressions were the kinetic equations of leaching reaction: 15～60min:1-(1-a)^1/3=5.48[H⁺]^1.08[Zn²⁺]^-1.76[Fe³⁺]^-1.39d₀^-1exp(-51792/RT)t+Ai 60³00min:1-(1-a)^1/3=7.87×10^-5[H⁺]^0.40[Zn²⁺]^-0.38[Fe³⁺]^-0.45d₀^-1exp(-20720/RT)t+A₂ where A1 and A2 are both constants.Process of the recovery of indium from neutral leaching residue has been investigated. The zinc sulfide concentrate was used as reductive reagent. The leaching ratio of Zn,Fe,Mn was 96.25%,86.5% and 96.76%, respectively, when neutral leaching residue bearing high iron and indium was circularly reductive and oxidative leached with high concentration acid at high temperature. The leaching ratio of...