Leaching kinetics of low grade zinc oxide ore in NH₃-NH₄Cl-H₂O system

Abstract

The leaching kinetics of low grade zinc oxide ore in NH₃-NH₄Cl-H₂O system was studied. The effects of ore particle size, reaction temperature and the sum concentration of ammonium ion and ammonia on the leaching efficiency of zinc were examined. The leaching kinetics of low-grade zinc oxide ore in NH₃-NY₄Cl-H₂O system follows the kinetic law of shrinking-core model. The results show that diffusion through the inert particle pores is the leaching kinetics rate controlling step. The calculated apparent activation energy of the process is about 7.057 kJ/mol. The leaching efficiency of zinc is 92.1% under the conditions of ore particle size of 69 μm, holding at 80 °C for 60 min, sum ammonia concentration of 7.5 mol/L, the molar ratio of ammonium to ammonia being 2:1, and the ratio (g/mL) of solid to liquid being 1:10.

Keywords

NH₃-NH₄Cl-H₂O system / low-grade zinc oxide ore / leaching / kinetics