The Chemical and kinetic mechanism for leaching of chrysocolla by sulfuric acid

Abstract

Batch experiments were conducted to determine the dissolution characteristics of chrysocolla using a computer controlled p11-Stat titration system. Dissolution can be described by the diffusion controlled shrinking core model with a 1:2 ratio of copper to proton; rate was inversely proportional to pH and ionic strength. Scanning electron microscope was used to investigate the possibility of secondary mineral precipitation. Secondary precipitation was not sufficient to affect the dissolution rate, however, the shrinking core model did indicate the formation of a residual silica layer. Chemical analysis of aqueous samples collected from the solution mining operation at the San Manuel Copper Mine indicated that the major ions were Al, Fe, Cu, Si0₂ and SO₄. Analysis of the saturation index illustrated the potential for formation of secondary surface coatings which may impact dissolution in the field. Geochemical computer models, PHRQPITZ, PHREEQE, SOLMINEQ, and WATEQ4F were selected to model both experimental and field results.