Determination of the direct reduction kinetics of Hekimhan siderite ore with hydrogen in a fluidized bed reactor

In this study, siderite ore, which was obtained from Malatya Hekimhan deposits and crushed and calcined, was reduced in a fluidized bed reactor with an H2 stream with a flow rate of 6 times the minimum fluidization rate, and the reaction kinetics of the process were determined. In the experiments, three different reaction temperatures of 700, 750, and 800 ºC and three different H2 concentrations of 10%, 25%, and 40% were studied. The degree of reduction of the ore was calculated with the help of the instantaneous concentration of the gas streams leaving the reactor. The obtained "Time-Degree of Reduction" graphs revealed that the process is more sensitive to H2 concentration than compared to temperature. Detailed kinetic analysis showed that the reduction consisted of a single step and proceeded under chemical reaction control (Ea=94.13 kJ/mol) by the "First-order reaction involving nuclear growth in one dimension, F1(α)" model. Since the carbonate in the ore was separated from the body during calcination, the reduction process started from the wüstite step, thus allowing high reduction degrees. As a result of the experiments, metallization rates varying between 95-99% were achieved.