Experimental Study On Reduction Of Fe And Zinc In Copper Slag

Fe and Zn in copper smelting slag are important to be reused as a kind of secondary mineral resource.The effects of technological parameters on Fe and Zn recycled ratio in copper slag were systematically researched,and the kinetic mechanism of the reaction process were also studied.The experiment adopts carbon-containing pellets for reduction,and the thermodynamic process is calculated by Factsage software.The thermodynamics analysis shows that temperature and carbon content are the main factors to affect the reduction of Fe and Zn.Ca O addition has a certain impact on the reduction process;Through the carbon reduction experiment,it can be concluded that the recycled ratio of Fe and Zn in copper slag increases with increasing reaction temperature and carbon content.The addition of Ca O enhances the recycled ratio of Fe and Zn as basicity is less than 0.4.The microstructure of iron develops from point-like and spot-like to strip-like and flake-like with the progress of reduction reaction.The zinc formed by reduction mostly volatilizes in gaseous form.The optimal parameters for the recycled ratio of Fe and Zn in copper slag are:reaction temperature 1200℃,carbon content（theoretical C/O）1.4,reduction time 45 min,coal powder particle size less than 150μm,basicity 0.4.The recycled ratio of Fe is 89.73%Zn recycled ratio is 98.65%,and the compressive strength of sample is about 5000 N under the above reaction conditions;For the copper slag without Ca O addition analyzed by the Jander equation,E_aof the reduction process is 310.48 k J·mol^-1;when adding Ca O（basicity less than 0.4）,the E_ais272.57 k J·mol^-1.The integral method analysis shows that the reduction process of copper slag includes three stages:initial stage,fast reaction and slow reaction.For the fast reaction stage:carbon gasification reaction controls the reduction process 1050～1100°C;the reaction is controlled by both the interfacial chemical reaction and the gasification reaction of carbon at 1150°C and 1200°C.For the slow stage,the reaction is controlled by the gas-phase diffusion inside the material.Figure 50;Table 27;Reference 77...