Thermodynamic and kinetic analyses of the decomposition of iron molybdate with soda ash solutions

Thermodynamics and kinetics of decomposition of iron molybdate in soda solutions was studied in order to optimize the molybdenum recovery conditions. The leaching was performed in a model circulating reactor with a stationary solid phase. An equation for the rate of the heterogeneous process was derived for the first time. In this equation, the concentration of the leaching reagent is functionally related to the conversion of the solid reagent. Factors of the optimizing effect of the molybdenum leaching process are considered. The optimal size of raw material particles is determined by the ratio between the leaching and suspension filtration rates. As the concentration of the soda solution is raised, it is necessary to take into account, in addition to the positive effect that consists in the increasing decomposition rate of iron molybdate, the possible quality deterioration of the target product due to the accumulation of the iron impurity in this product.