Sustainable Mining and Metallurgy

This article has carried out the research of smelting nickel slag modification. Firstly, the relationship between Gibbs free energy of main reactions and temperature during smelting nickel slag is obtained by thermodynamic calculation, which shows that under the conditions of 750~1600℃, coke powder as reductant and limestone as flux, all main reactions can occur. On this basis, combined with the theory of increasing calcium and decreasing silicon, nickel slag was modified in the high temperature box resistance furnace to obtain a reasonable slag type. The effects of limestone addition, iron silicon ratio and temperature on the content of nickel and copper in nickel slag were discussed, and the effects of calcium oxide and limestone on the properties of nickel slag were studied. The test results show that under the conditions of smelting temperature 1420℃, iron silicon ratio 1.2~1.3, limestone content 9%~11%, and settling time 60min, the nickel content and copper content can be reduced to 0.37% and 0.27% respectively, reducing the mechanical inclusion loss and chemical dissolution loss of nickel copper valuable metals in nickel slag. The XRD phase analysis of the modified nickel slag shows that the addition of limestone will destroy the complex iron magnesium silicate structure and transform it into a Fe2SiO4 structure with simple structure and easy reduction. The modification effect of limestone on nickel slag is better than that of calcium oxide. This study is beneficial to reduce the loss of valuable metals in nickel slag, and lays a theoretical and practical foundation for the research on slag type of nickel smelting system.