Study On The Kinetics Of Hydrogen Carbon Coupling Reduction From Coal Based Iron Rich Nickel Slag

The total iron(TFe)content in Jinchuan nickel slag is about 40%,which can be regarded as a valuable iron ore resource.In this study,a green and low-carbon coal-based process,a hydrogen-carbon coupling reduction process,was adopted for the efficient reduction of the nickel slag,and the kinetics of the hydrogen-carbon coupling reduction has been investigated in depth.The reaction order was obtained by the simulation analysis of experimental data.The rate-controlling factors of different reaction stages were clarified,the kinetic model was established,and the reaction mechanism of the hydrogen-carbon coupling reduction was revealed.These studies provided a theoretical basis for the exploration of green and efficient iron extraction from nickel slag.The specific conclusions of the study are as follows:(1)In the temperature range of 1200°C-1300°C,the metallization rate of Fe O pellets doped coal could reach more than 80%after 4 min reduction.When the temperature increased from 1200°C to 1300°C,the reaction order(n)of the coal-based hydrogen-carbon coupling reduction for Fe O was calculated to be 1.63 to 1.33 by differential method,and the reaction rate constant increased from 0.031 to 0.165.This means the reaction rate constant of the reduction reaction gradually increased with the increasing reaction temperature.(2)The metallization rate of the pellets containing nickel slag and coal increased effectively by increasing the reduction temperature and prolonging the reduction roasting time.The metallization rate of these pellets can reach 94.26%after 60min reduction at1300°C.Phase analysis showed that the olivine in nickel slag was mostly converted to metallic iron and pyroxene,and the reduction degree of the outer layer of the pellets was greater than that of the inner layer.(3)Based on the particle model theory,the kinetic model of coal-based hydrogen-carbon coupling reduction for the pellets containing nickel slag and coal was established,and the kinetic equations of different reaction stages were obtained.Early reaction stage:interfacial chemical reaction controls the reaction rate,and the corresponding kinetic equation is (?)Middle reaction stage:interfacial chemical reaction and internal diffusion both control the reaction rate,and the corresponding kinetic equation is (?)Late reaction stage:internal diffusion control the reaction rate,and the corresponding kinetic equation is (?)...