Optimization and kinetics studies of lead concentrate leaching using fluoroboric acid

In this study, the feasibility of lead dissolution from lead concentrate using fluoroboric acid by hydrometallurgical method was investigated in order to aviod the disadvantages of the pyrometallurgical processes. The effects of important operating parameters such as leaching time, liquid/solid ratio, stirring speed, temperature and fluoroboric acid concentration on the lead recovery were investigated using response surface methodology (RSM) based on the central composite design (CCD) model. The results show that the optimum conditions for the high lead recovery were: leaching time= 30 min, liquid/solid ratio= 10, stirring rate= 500 rpm, temperature= 80oC and fluoroboric acid concentration= 3.35 mol/L. More than 94% of lead was recovered in the optimum conditions. The results indicated that the liquid/solid ratio, fluoroboric acid concentration, temperature and leaching time were the most effective parameters on the process efficiency, respectively. Dissolution kinetics studies of lead in the fluoroboric acid were also evaluated. The chemical reaction was determined as the controlling mechanism of reaction at the shrinking core model. The activation energy was determined using Arrhenius model as 5.99 kJ/mol.