Leaching of Lead and Zinc from a Low-Grade Oxide Ore in Citric Acid Media

Leaching of a low-grade lead and zinc oxide ore was studied by an organic reagent, citric acid. The quadratic mathematical models were developed for the relationship among the influential parameters and lead and zinc recoveries. Leaching rate was strongly affected by the interactive effects of factors. It was also found that the quadratic effects of stirring speed and linear effects of temperature have the most significance on the leaching rate of zinc and lead, respectively. It was found that the center level of influential factors was a good condition for getting higher zinc leaching rate, whilst, for the leaching of lead the extreme levels of factors were good. Additionally, the proposed models were optimized using the quadratic programming method to maximize recoveries. The highest recoveries of zinc and lead were achieved to be about 94 and 78 %, respectively.