Mechanism Of Action Of Iron Ions During Oxygen Pressure Acid Leaching Of Zinc Sulfide Concentrates

As an important non-ferrous metal resource,zinc plays an important role in the national economy.At present,more than 80%zinc is extracted by hydrometallurgy.Although the oxygen pressure leaching process of zinc sulfide concentrate has been widely used in the hydrometallurgical zinc smelting industry,the action mechanism of iron ions in the leaching process needs to be further studied.Therefore,the mechanism of action of iron ion in the process of oxygen pressure leaching of zinc sulfide concentrate was studied in this paper.The main research contents and conclusions are as follows:(1)Potential-pH diagram was drawn by Factage thermodynamics software,and the conversion conditions of ZnS and elemental S⁰were studied by the temperature,pressure and pH value of the acid leaching system under oxygen pressure of zinc sulfide.The results show that the increase of temperature and pressure can promote the transformation of ZnS into Zn²⁺,S^2-and H₂S into elemental S⁰,and the presence of Fe²⁺in the solution can promote the formation of stable elemental S⁰(2)Taking zinc sulfide concentrate as raw material,the effects of leaching temperature,initial acidity,stirring speed,oxygen partial pressure,liquid-solid ratio and additives on the leaching rate of zinc and iron and sulfur conversion and zinc leaching kinetics in the process of oxygen pressure acid leaching of zinc sulfide concentrate were studied,and the iron ion in the leaching solution was detected.The results show that the leaching mechanism of zinc is controlled by chemical and electrochemical mixing.The calculated activation energy E is 67.11k J/mol,which indicates that the leaching process is controlled by surface chemical reaction.The kinetic equation of zinc leaching is obtained.(3)MS(Materials TTUDIO 8.0)CASTEP,DMOL3 and ADsorption were used in this study The Locator module simulated the effects of the substitution of Fe atom by Zn atom in the center of the ZnS lattice on the electronic structure,energy energy band,Zn-S bond length and the interaction energy with solvent of the ZnS lattice.The results show that the electron nonlocalization and electron transition probability of ZnS lattice are enhanced after Fe atom substitution,and the adsorption energy between ZnS(110)surface and solvent components H₂SO₄,_H2S and O₂is greater,which is beneficial to chemisorption.(4)by integrated thermodynamic calculation,leaching experiment and numerical simulation,and the existing results,to determine the zinc sulfide concentrates oxygen pressure acid leaching process mechanism to contain acid erosion mechanism of fe ion electrochemical dominated mixed mechanism,including zinc sulfide concentrate in acid erosion,will be acid dissolved into the solution iron minerals,produce Fe³⁺and Fe²⁺as electroactive material,Then,the electrochemical mechanism gradually dominates the leaching reaction.This process gradually strengthens until equilibrium under the condition of oxygen pressure acid leaching,and finally stops with mineral consumption.