Spherical sponge iron (SSI) with high activity and intension could be prepared through direct reduction by hydrogen. To optimize the reduction technology, kinetic model of SSI reduction was established. The total reaction rate changing with reduction index R was deduced which describing the total reaction rate with effective diffusion coefficient De and chemical reaction rate constant k. According to the weight loss curve of SSI reduction, De and k were calculated. The total reactive rate increased with the increasing of temperature because both De and k increased with the increasing of reaction temperature. Compared De with k, it concluded that SSI reduced by hydrogen was controlled by the chemical reaction, combination of the chemical reaction and the internal diffusion, the internal diffusion when the temperature was lower than T3, from T3 to T4, over T5, respectively.
Search for optimal conditions for a chemical reaction based on a kinetic model