Promoting the Effective Utilization of Limonitic Nickel Laterite by the Optimization of (MgO + Al2O3)/SiO2 Mass Ratio During Sintering

Limonitic nickel laterite always contains abundant high smelting components such as Al2O3 and MgO, which is extremely adverse to sintering. To weaken the negative effect of the abundant high smelting components, in this study, sinter pot tests of limonitic nickel laterite were conducted for better sintering performance by the optimization of (MgO + Al2O3)/SiO2 mass ratio at the same basicity. The relevant mechanism was revealed by the theoretical analysis and the measurement of chemistry and mineralogy of product sinter. At the optimum (MgO + Al2O3)/SiO2 mass ratio of 1.10, better sintering performance of limonitic nickel laterite can be achieved with tumble index and productivity increased by 8.22% and 7.22%, respectively, and solid fuel rate reduced by 7.41% compared with that of base case. Metallurgical performance of product sinter is excellent with reduction index (RI) and reduction degradation index (RDI+3.15 mm) of as high as 83.66% and 95.64%, respectively. In this case, liquid phase volume and fluidity are both significantly improved and nicely suitable for sintering. The optimization of (MgO + Al2O3)/SiO2 mass ratio contributes to the homogenization of liquid phase and the generation of tighter sinter microstructure with the obvious reduction of sinter porosity, the more formation of silico-ferrite of calcium and alumina (SFCA) and the improvement of bonding efficacy of solid phase by liquid phase. In the follow-up study, (MgO + Al2O3)/SiO2 mass ratio is considered to be adjusted by adding another type of nickel laterite with relatively lower MgO and Al2O3 contents for further improving limonitic nickel laterite sintering and eventually achieving its effective utilization.