Contaminants of post-leaching copper solutions and their behavior during extraction with industrial extractants

Abstract

Several copper extractants have been examined in laboratory glassware with a special attention paid to their behavior towards cations others than copper(II). In the studies 25 vol. percent of hydrocarbon (Exxsol D80 AZ) solutions of six industrial copper extractants have been used. They were mainly rea- gents of hydrooxime type (LIX 860N-IC, LIX 984, LIX 984N, LIX 84-I, Acorga M5640) and diketone type LIX 54-100. Individual isotherms of independent extraction of copper(II) and selected cations (Fe 3+ , Fe 2+ , Co 2+ , Ni 2+ , Zn 2+ , Mn 2+ , Cd 2+ , Mg 2+ ) versus equilibrium pH have been compared. Investigations have been conducted with synthetic 0.1 mol/L solutions of their sulfates. The values of pH50% − parameter defined as an equilibrium pH at the moment of half-and-half extraction of the investigated cationic spe- cies have been presented. Also ΔpH50%, that is differences between values of pH50% for specific cation Me(II) and copper(II): ΔpH50% = pH50%(Me) − pH50%(Cu), have been given. In addition to that 25% LIX 984 has been used in counter-current pilot trials for copper(II) extraction from naturally contaminated solutions produced by bioleaching of industrial sulfide copper concentrate to observe behavior of investi- gated contaminants such as correlations between their real co-extraction with copper(II) and the position of their extraction on the pH scale. Copper electrolyte/strip solution, working alternately within close loop of coupled stripping - electrowinning system, has been analyzed during consecutive cycles to observe building up of the contaminants concentrations in the course of test.