Leaching Kinetics of Secondary Zinc Oxide in a NH3–NH4HCO3–H2O System

Secondary zinc oxide (SZO), which comes from the industry, is an important secondary resource of and other valuable metals. In this study, production feasibility rationality a cleaner recovery process using SZO hydrometallurgical method were described. Zinc extraction promoted by addition ammonium bicarbonate to NH3–H2O system, maximum could be close 80% at optimum leaching conditions stirring rate 400 rpm, ammonia/ammonium ratio 7:3, total ammonia concentration 4 mol/L, liquid/solid 7 mL/g for 30 min 35 °C. The kinetics modeled shrinking core model constant-size particles, rate-controlling step was determined diffusion through product layer. apparent activation energy reaction estimated 11.04 KJ·mol−1, while order with respect 1.53 2.26. analysis results initial residue leached indicated that lead transferred PbCl2 PbCO3 ZnFe2O4 not in NH3-NH4HCO3-H2O system.