EFFECT OF MIXING METHODS PRIOR THE DECOMPOSITION PROCESS ON THE DECOMPOSED FERRONICKEL SLAG

Ferronickel slag is a by-product that was obtained from ferronickel production and contains Si and Mg as the main elements. Decomposition process using alkali could decrease energy consumption to process ferronickel slag by decreasing its melting point.  The mixing methods prior to the decomposition process could significantly affect interaction between reactants over the process, therefore it is essential to study. The aim of this study is to determine the effect of mixing methods of ferronickel slag and NaOH prior decomposition process on the chemical composition, phase, and microstructure of decomposed ferronickel slag. Two different mixing methods, physical mixing, and impregnation, followed by roasting process at 350 ℃ for 60 minutes were performed, characterized, and analyzed. Thermodynamic analysis was calculated and shows having a good agreement with the characterization results which formation of sodium silicate, magnesium hydroxide and iron oxide were identified. Distribution of product layer of RI can be determined, while spotty decomposition was clearly identified. The effectiveness of impregnation over physical mixing was investigated.