The New Technology Of Enhancing Indium Leaching From Zinc Oxidation Slag Dust

Based on the summary of the investigations on the leaching process of indium,zinc oxidation slag dust as well as the application of mechanical activation and pressure oxidation in non-ferrous metallurgy,the effects of different technologcial conditions and leaching process on leaching efficiency of indium in the reaction of zinc oxidation slag dust with sulfuric acid by mechanical activation or pressure oxidation was studied,we can get the optimum conditions of leaching indium.From the experiments,conclusions can be drawn as follow:(1)The technology of leaching indium in the reaction of zinc oxidation slag dust with sulfuric acid by mechanical activation or pressure oxidation with oxidant can improve the leaching efficiency of indium and decrease the leaching time.So two new path for enhancing leaching indium from zinc oxidation slag dust can be provided.In the orthorhombic experiment of mechanical activation in a stirring mill,the effect of each factor on leaching efficiency of indium is:the initial concentration of acid＞stirring speed＞reaction time＞ratio of liquid-solid.(2)Associating with the equipment and the cost of energy,the optimum conditions of leaching indium by the mechanical activation in a stirring mill are:the reaction time is 150 min,the ratio of liquid-solid is 8,the initial concentration of sulfuric acid is 5 mol/L,the stirring speed is 575 r/min.In the optimum conditions the leaching efficiency of indium which was 68.0%in conventional leaching process was improved to 91.2%.(3)Associating with the equipment and the cost of energy,the optimum conditions of leaching indium by pressure oxidation with hydrogen peroxide in a high pressure reaction kettle are:the reaction time is 150 min,the ratio of liquid-solid is 8,the initial concentration of sulfuric acid is 5 mol/L,the stirring speed is 575 r/min,reacting temperature is 90℃,air pressure is 0.5 MPa,the dosage of 30%hydrogen peroxide is 0.5 mL/g.In the optimum conditions the leaching efficiency of indium which was 77.6%in conventional leaching process(90℃)without oxidant was improved to 90.2%.The optimum conditions of leaching indium by pressure oxidation with potassium permanganate in a high pressure reaction kettle are:the reaction time is 150 min,the ratio of liquid-solid is 8,the initial concentration of sulfuric acid is 3 mol/L,the stirring speed is 575 r/min,reacting temperature is 90℃,air pressure is 0.5 MPa,the dosage of potassium permanganate is 25 g/kg.In the conditions the leaching efficiency of indium which was 77.6%in conventional leaching process(90℃,the initial concentration of sulfuric acid is 5 mol/L)without oxidant was improved to 89.5%.(4)In the condition of dilute initial concentration of acid,the leaching efficiency of indium is better in pressure oxidation process than mechanical activation process because of the application of hydrogen peroxide in the leaching process.In the condition of dilute initial concentration of acid,we can get the best leaching efficiency of indium by pressure oxidation with potassium permanganate.And when the initial concentration of acid is dense,the leaching efficiency of indium by pressure oxidation with potassium permanganate is the best in all of the processes.