Research On Direct Reduction Of Copper Concentrate

Based on sulfide copper concentrate as raw material,adding proper reductants and additives,direct reduction process of copper has been studied,which can not only shorten and simplify the whole process,but also reduce the emission of sulfur dioxide by immobilizing the sulfur elements inside of the copper concentrates into slags in the form of CaS.Under the circumstance of the seriously polluted environment,direct reduction process of copper is of great importance,which has a great prospect for development.The main results are as follows:(1)The thermodynamic calculation indicates that the chalcopyrite decomposition temperature in copper concentrates T=1099K is the chemical reaction control process in the entire system.When T>1099K,the chalcopyrite decomposes into bornite,then the carbothermal reduction continues to react.Thus,the metallic copper can be collected in the reduction products.(2)This paper investigates the effects of carbon content,calcium oxide amount,reduction temperature,reduction time,and adding additives like NaF,Na2CO3,K2S2O7 on reduction rate in the direct reduction of copper concentrates.The optimum reaction conditions without additives:the stoichiometric ratio of CuFeS2,CaO and anthracite powder is 1:2:2,the reduction temperature is 1273K,the reduction time is 120 minutes and the reduction rate of copper in copper concentrates is 68%.The optimum reaction conditions with additives:the stoichiometric ratio of CuFeS2,CaO and anthracite is 1:2:2;adding 3wt%NaF,the reduction temperature is 1123K,the holding time is 90 minutes and the reduction rate of copper in copper concentrates is 78%.(3)The occurrent state of the direct reduction of copper concentrate shows that the separate of copper and iron phase in the reduction products provides a theoretical basis for the separation of copper and iron;if CaS phase exists in the reduction products,which indicates that the sulfur elements inside of copper concentrates fixed into the reduction products in the form of CaS phase,instead of generating SO2,the purpose of environmental protection and cleaner production can be achieved.(4)The research on kinetics shows that the main reaction temperature of direct reduction ranges from 750? to 900?;as the temperature increases,the exothermic reaction becomes more intense and the empirical formula of the rate constant K,reaction kinetics mechanism functions f(?)= 1-?,all stages of preexponential factor A,activation energy E(350?450?,E=0.1571kJ·mol-1;450?750? E=0.0612kJ·mol-1 750?900?,E=0.0971 kJ·mol-1)and kinetic equation can be finally obtained.