Leaching Kinetics of the Pressure Decomposition of Wolframite with Sulfuric-Phosphoric Mixed Acid

To further improve the decomposition efficiency of wolframite in sulfuric-phosphoric mixed acid, the leaching kinetics in pressurized system was studied. The effects of stirring rate, reaction temperature, sulfuric acid concentration, phosphoric acid concentration, and mineral particle size on the leaching process were investigated, and the data could be fitted by the Avrami equation with a fitting degree of 0.9824. When the stirring rate exceeds 500 r/min, the liquid phase mass transfer was relatively sufficient, and the apparent activation energy of the reaction was 41.98 kJ/mol, which indicated chemical reaction control. And the reaction characteristic parameter was 0.44, the influence index of mineral particle size was - 1.78, and the reaction order of sulfuric acid concentration and phosphoric acid concentration were 0.4 and 0.31, respectively. The kinetics equation of the pressure sulfuric-phosphoric acid decomposition wolframite was obtained. It provided a theoretical basis for the strengthening of practical decomposition of wolframite.