The effect of NaCl on the leaching of white metal from a Teniente Converter was investigated in NaCl-H2SO4 media under environmental conditions. The copper dissolution from white metal was studied using ferric ions in the range of 1–10 g/L, NaCl in the range of 30–210 g/L, and sulfuric acid in the range of 10–50 g/L. The test without NaCl produced a dissolution of 55%; through the addition of NaCl, the dissolution increased to nearly 90%. The effect of sulfuric acid on the copper dissolution was not significant in the studied range, as the excess sulfuric acid simply increased the iron precipitation. The positive effect of NaCl seems to be related to the action of chloro-complex oxidizing agents in relation to the Cu+2/Cu+ couple. A simplified two-stage mechanism is proposed for the leaching of white metal. In the first stage, the white metal produces covellite and Cu2+, and in the second stage it produces elemental sulfur and Cu2+. The first stage is very rapidly compared to the second stage.

In this study, weak acid in the curing and leaching stages of copper ore was incorporated, and we analyzed its effect on the dissolution of copper and final impurities. The weak acid corresponds to a wastewater effluent from sulfuric acid plants produced in the gas treatment of copper smelting processes. This effluent is basically water with high acidity (pH-value low at 1), which contains several toxic elements and some valuable metals. The results indicated that there is no positive or negative effect on the incorporation of the weak acid in the curing stage, while the case of the leaching stage is favored. Toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) toxicity tests were performed on the solid leaching residues, determining that they accomplish the stability ranges of the impurities (Pb, Cd, Hg, Cr, Ba, Se, As, and Ag).

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