Effect of Quaternary Basicity on Melting Behavior and Ferronickel Particles Growth of Saprolitic Laterite Ores in Krupp–Renn Process

Abstract

Krupp–Renn process is an energy-saving technology for ferronickel production from saprolitic laterite ores, in which a semi-fused zone (1300–1350°C) in the rotary kiln is required for the coalescence of ferronickel particles. Fluxes are crucial for the liquid phase formation during the coalescence stage. In this study, effect of quaternary basicity ((CaO+MgO)/(Al₂O₃+SiO₂) mass ratio) on the melting characteristics of laterite ore blended with various amount of CaO in 100% CO atmosphere are investigated, and the growth of ferronickel particles is also observed. It is shown that the characteristic fusion temperatures first decline and then increase with increasing of basicity, which is closely related with the presenting silicate minerals in the reduced products involving olivine, diopside, monticellite, akermanite and merwinite. At the basicity of 0.8–1.2, the characteristic fusion temperatures drop subsequently before reaching a minimum (~1300°C), due to the generation of low-melting-point diopside. The growth of ferronickel particles is improved by the presence of liquid phase.