Abstract

Chile is host to one of the most considerable Cu resources in the world. The primary source of Cu is from porphyry deposits. However, associated "exotic-Cu" deposits are also significant in the Atacama Desert of northern Chile. The critical processing issue for these ores is that they are refractory to dissolution under acidic and oxidative conditions, and consequently their dissolution kinetics are relatively slow. This paper reports a study on the extraction of copper and manganese from exotic-Cu ores using cane molasses as a reducing agent in the presence of chloride ions and diluted sulfuric acid media. The effects of concentrations of cane molasses, chloride ion, and sulfuric acid are discussed. Leaching tests on ground ore in shake flasks were studied, as well as the agglomeration and curing stages of a coarse ore sample. The dissolution of the exotic copper ore is enhanced when 50 g/L of NaCl and 60 g/L of cane molasses are added to the leaching solution. The dissolution of copper associated with copper wad appears independent of the Mn dissolution. Tests with the ore agglomerated with acid, chloride ions, and cane molasses showed enhanced dissolution of manganese contained in the copper wad, but not copper. It is thus confirmed that cane molasses is a suitable reductant in the leaching of Mn, especially in the presence of chloride ions. The behavior and fate of the wad-associated copper requires further investigation.