Consolidation mechanisms and Ni-Fe enrichment pathways in three types of lateritic nickel ore pellets during basicity-controlled oxidative roasting

Abstract

This study investigates the migration behavior of nickel and iron and the consolidation of lateritic nickel ore pellets during oxidative roasting, essential for ferronickel production. Three lateritic nickel ores were selected, and the effects of basicity and roasting conditions on pellet consolidation were analyzed. Results show that chemical composition and phase structure significantly influence both pellet consolidation and the migration of nickel and iron. Thermodynamic calculations combined with microstructural analysis revealed that roasting temperature and basicity govern pellet densification and mechanical strength. At a basicity of 0.2, the compressive strengths of saprolitic, transitional, and limonitic pellets were 1305 N/P, 1516 N/P, and 402 N/P, respectively, at optimal roasting temperatures of 1270 °C, 1285 °C, and 1300 °C. This is attributed to enstatite’s reaction with CaO, forming diopside, which lowers the melting point and facilitates densification. CaO also disrupts enstatite’s lattice, aiding nickel liberation and promoting nickel – iron enrichment. This study provides a theoretical basis for the subsequent preparation of nickel – iron via direct reduction and magnetic separation.

Keywords

lateritic nickel ore / consolidation behavior / oxidative roasting / Ni-Fe enrichment

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