Producing ferronickel via direct reduction of Gördes laterite in fluidized bed reactor

In this study, the laterite ore supplied from Manisa Gördes mine was crushed and calcined, afterward the calcined ore was reduced at a fluidized bed reactor by H2 stream with a volumetric rate 6 times the minimum fluidization velocity and the reaction kinetics of the process was determined. The reduction tests were performed at 700, 750, 800 and 850 ºC reaction temperatures using 10%, 25% and 40% H2 concentrations. The reduction degree of the ore was calculated with the help of the instantaneous concentration of gas streams leaving the reactor. The obtained "Time-Reduction Degree" graphs revealed that the process is more sensitive to H2 concentration compared to the temperature, this finding supports the idea that the process proceeded mainly under diffusion control. Detailed kinetic analysis revealed that the reduction consisted of 3 stages; the first progressed under chemical reaction control according to the "Contracting Sphere, R3(α)" model (Ea=34.76 kJ/mol), and the second progressed under diffusion control according to the "One Dimensional Diffusion, D1(α)" model (Ea=10.18 kJ/mol). No model representing the third stage, which proceeds with an extremely low reaction rate, has been found. The sintering caused by the high reaction temperature and the hardly reducable nature of the trevorite mineral in the ore limited the highest reduction degree obtained in this study to 81%.