New Technology Of Demineralized Sulfur And Silver Extraction From Zinc Mine Slag Magnetic Separation Iron Concentrate

The leaching slag produced by Zinc hydrometallurgy process after volatilization roasting in rotary kiln, which has high iron content. The slag after magnetic separation get the iron ore concentrate which is potential raw materials for ironmaking. The process of remove arsenic and sulfur, and revover silver from the iron ore concentrate which magnetic selected from Zinc kiln slag, it belongs to a comlex resource utilization and it has theoretical and practical significance. Against to the iron ore concentrate which rich in sulfur,arsenic and silver, This article adopts "two stage calcination process contacts steam calcination with air calcination "to remove arsenic and sulfur. The purpose is to reduce the levels of arsenic and sulfur of the iron ore concentrate, in order to achieve the iron requirements. And this article adopts sulfuric acid pre-thiourea leaching process to recover silver from iron ore concentrate.The research of roasting in steam condition obtains the following conclusions:(1) To reveal the rule of the particle size of grinding circuit, the roasting temperature, the constant temperature time, carbon content, the steam flow and the gas composition effects on the roasting process.(2) In the roasting in steam condition:when the particle size of grinding circuit is-160mesh, roasting temperature is850℃, constant temperature time is3-4hours, carbon content is10%, steam flow is200L/h, the arsenic removal rate is84.67%, arsenic content of roasted product is0.069%, removal rate of sulfur is71.88%, sulphur content of roasted product is2.05%. And is roasted under the air atmosphere at900℃for60min, removal rate of sulfur is71.88%. Then the total arsenic removal rate is85.56%, arsenic content of roasted product is0.065%, total removal rate of sulfur is93.56%, sulphur content of roasted product is0.47%.The iron is enrichment effectively, get TFe grade over62%iron concentrate.The research of acid pre-thiourea leaching process obtains the following conclusions:(1) In acid presoak process:When ratio of liquid to solid is10:1, pH is0-1.0, leaching temperature is70-80℃, the leaching time is1.0-1.5h; and in the thiourea leaching process: when leaching time is120min, concentration of thiourea and Fe3+is lOg/L and O.Olmol/L, ratio of liquid to solid is10:1, and leaching temperature is room temperature, the leaching efficiency of Ag is85.23%.(2) Through thermodynamic calculation, the gibbs energy of the Ag and Ag^S by thiourea leaching is-84.022kJ/mol and-80.915kJ/mol.(3) The unreacted and shrinking core model is used for study on kinetics of thiourea leaching of Ag. The results show that the kinetics equation is the reaction apparent reaction progression of thiourea is0.68; the apparent activation energy of reaction is5.725kJ/mol, the leaching reaction is mostly controlled by the solid membrane diffusion process.The test results show that, the iron ore concentrate magnetic selected from Zinc kiln slag through the processing of "two stage calcination process contacts steam calcination with air calcination and acid prepreg-thiourea leaching ". Compared with the results of conventional calcination which was adopted by factory, the Arsenic removal increased from53.2%to85.6%, the removal rate of arsenic increased more than30%. At the same time, the As removal as As2S3at the test, which could also reduce the pollution of the environment.