Dump leaching dissolution reactions

We now discuss in detail setting up the partial equilibrium model for a particular case. The dissolution of chalcopyrite, CuFeS2, has been studied extensively in the laboratory ( 3,4 5) and we have been interested in it because of its importance in dump leaching. Under dump leaching conditions, two dissolution reactions have been identified for this mineral (3,4 5) ... 

The factors that determine the choice lof solvent for a given ore are dependent on the nature of the mineralization and association of the metal values with the unwanted bulk of the ore. Since in the process of dissolution of the desired metal, other metals are also simultaneously going into solution, the minimization of the unwanted side reactions becomes very important in the final choice of a solvent. It must be remembered that the concentration of the recoverable metal in the ore very seldom exceeds 1% and in most cases is only a fraction of 1%. In the dump leaching of copper waste dumps, an average value of 0.30% is... 

Between 45 and 90°C, the reaction of cubanite with acidic ferric sulfate solutions followed linear kinetics, indicating that the rate-controlling step was some reaction occurring on the surface of the cubanite. The dissolution rate increased with ferric ion concentration and decreased with increasing concentration of sulfuric acid and ferrous sulfate. The naturally slow reaction was accelerated with the addition of NaCl or HCl. The addition of salt in a dump leaching operation would be a relatively easy and cheap procedure to attain increased reaction rates. 

The dissolution reactions typically of importance in copper dump leaching are ... 

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