Investigations on mineralogical characteristics of Indonesian nickel laterite ores during the roasting process

Abstract

Nickel is obtained from laterite ores by a metallurgical process to produces ferronickel. Nickel metal is present in a carrier mineral, a nickel magnesium silicate hydrate compound called garnierite. Garnierite is the common name of magnesium silicate hydrate minerals including chlorite, clay and serpentine. This study to investigate the phase formed when the nickel ore is roasted from a temperature of 600°C to a temperature of 1000°C under atmospheric enviromental. Microscopic analysis of roasted samples was analyzed by SEM-EDX and the dehydroxylation and recrystallization was studied using DTA-TGA. The endothermic peak was appear at 78.8°C, 293.7°C and 638.0°C, this corresponds to the release of free water and the release of crystalline water. While the exothermic peak occurs at 828.0°C. The exothermic temperatures associated with structural changes due to dihydroxylation of serpentine into a forsterite phase. Based on the XRD graph it is known that the sample of the roasting will produce the olivine and forsterite phases.