Recuperação hidrometalúrgica de cobre e zinco a partir de cinzas de fundição de latão utilizando extração por solventes com D2EHPA

Abstract

A blend of brass ashes sample was processed through leaching and solvent extraction aiming to separate zinc and copper, the predominant species found in the residue, i.e., 48% of zinc and 16.6% of copper. The present study was performed in bench and pilot scales using sulfuric acid as leaching agent and D2EHPA as extracting agent. The following operating parameters were evaluated in the solvent extraction step: time, pH, D2EHPA concentration, A/O ratio in the extraction step and O/A ratio in the stripping step. Zinc present in the brass ashes was efficiently leached by H2SO4 (recovery of 91.9%), whereas only 8.6% of copper was leached, as well as selectively extracted over copper by solvent extraction with D2EHPA. A continuous solvent extraction run in pilot scale was carried out using 4 extraction stages (pH = 2, A/O ratio = 1) and 2 stripping stages (O/A ratio = 2), where 91.8% of zinc extraction and 96.9% of zinc stripping were achieved. Iron extraction efficiency reached 85.9%, thus evidencing the need for previous removal if required. The fluorine extraction was 29.9% and that for chlorine was 10.4%, whose extractions are related to iron and zinc extractions, respectively, as evidenced by species speciation analysis. As copper was not efficiently leached by sulfuric acid, a copper concentrate containing 42.2% was produced.