Leaching kinetics of zinc silicate in ammonium chloride solution

The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed (150-400 r/min), leaching temperature (95-108 degrees C), particle size of zinc silicate (61-150 mu m) and the concentration of ammonium chloride (3.5-5.5 mol/L) on leaching rate of zinc were studied. The results show that decreasing the particle size of zinc silicate and increasing the leaching temperature and concentration of ammonium chloride can obviously enhance the leaching rate of zinc. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control can well describe the zinc leaching kinetics. The apparent activation energy of the leaching reaction is 161.26 kJ/mol and the reaction order with respect to ammonium chloride is 3.5.