Effects of reduction time on carbothermic reduction of lateritic nickel ore using palm kernel shell as green reducing agent

Abstract

Lateritic nickel ore is one of the biggest mineral resources in Indonesia. This ore has a huge potential, i.e., economic value for processing and purification, however requires high energy in the separating of mineral and gangue minerals, in addition the production cost is also high. Therefore, to resolve the problems, a pre-reduction stage called carbothermic reduction process is carried out. Carbothermic reduction process is usually used for saprolite-type lateritic nickel ore which needs a reductor for the reduction reaction to produce pure nickel. Common reductors used are coal and cokes. In this study, a development on carbothermic reduction of saprolite, type of lateritic nickel ore using biomass reductor palm kernel shell, is proposed. The lateritic nickel ore used is obtained from East Halmahera and the palm kernel shells are obtained from the waste of palm oil plantation at Palangkaraya, Central Kalimantan. The purpose of this study is to find out the effect of reduction time variation on carbothermic reduction result of lateritic nickel ore with constant temperature and mass ratio value. Reduction time variation used in this study was 1, 2, 3, and 4 hours. All samples were tested at 800°C with the mass ratio of 1:4 (lateritic nickel ore : palm kernel shell) which were put into a crucible and then the carbothermic reduction process was done in a melting furnace. Peak formed on the XRD pattern showed that the process was able to reduce hematite or magnetite to wustite within one hour. XRF and recovery calculation results showed that the reduction time of one hour is the optimum time because nickel oxide (NiO) content was the highest i.e. 2.68% compared to other time variation.