Dissolution of sphalerite minerals from Rosh Pinah tailings

Abstract

The aim of this study was to study the extraction of zinc from the mineral sphalerite, especially the leaching of concentrate recovered from the Rosh Pinah tailings by means of ferric chloride. To this end, the literature on zinc processing was surveyed and knowledgeable persons were consulted. The study also addressed the leaching kinetics of an upgrade Rosh Pinah tailings dam concentrate as well as those of a synthetic zinc sulphide in a ferric chloride medium. Valuable results were obtained, from the leaching of sphalerite concentrate in ferric chloride medium. An activation energy value of 45.82 kJ/mol was obtained, which compares well with what has been published in the literature. A chemical control model and a diffusion control model were applied to the data obtained. From neither of the models a straight-line relationship could be deduced over the leaching range. At t < 45 minutes it seems that the process is controlled by chemical reaction at the interface; at t > 45 minutes it seems that the process is controlled by diffusion through the product layer. If therefore seems that the rate-controlling step can be related to the process of diffusion through the product layer. The mixed control model proposed by Huang and Rowson, [1-(1-x)1/3+y/6[(1-x)1/3+1-2(1-x)2/3]=kMt, was applied to data obtained during this study. The resultant graphical fit was near perfect, indicating that sphalerite leached in ferric chloride follows a mixed control mechanism for the conditions reported in the study. An activation energy of 20.71 kJ/mol was determined for this model by using the following equation: