Briquette Shape Roles in Carbothermal Reduction Process of Limonitic Laterite Nickel

Lateritic ore carbothermal reduction is currently the focus of many researchers. This process uses a relatively lower temperature of operation than the smelting. Therefore, the carbothermal reduction process has a relatively lower primary energy demand and CO2 gas emissions. This research examines the appropriate briquette form to obtain the optimum recovery, concentration of nickel, and selective reduction of nickel, as well as analyzes the compounds/phases formed. The briquette in this study was formed into three different geometries, i.e., the pillow, spherical, and cylindrical forms. First, this research was carried out by mixing the raw materials and forming it into specified briquette forms. Second, the formed briquettes were put into a crucible. Third, the coal-limestone bed mixture was used to cover the briquettes. Then, the carbothermic reduction process was started by heating to 700 oC for 2 hours and continued to 1400 oC for 6 hours. Finally, the magnetic separation process was performed to separate the reduced briquettes. As a result, the cylindrical shape briquette obtained better results at 6.74% Ni, with a nickel recovery of 96.20% and a selectivity factor value of 10.39. The compounds formed after carbothermic reduction process products include FeNi, Fe3Si, and SiO₂. In a spherical-shaped briquette, Fe3O4 and Mg₂SiO₄ were found in the reduced product, indicating impurities in the reduced briquettes.