Dump leaching

The foHowing factors are important in dump leaching (/) the role of bacteria (2) the appHcation of acid to prevent or delay precipitation of hydrated ferric sulfate (J) oxidation to remove excess iron from mine water in settling pools, as shown in equations 38 and 39 (4) optimization of dump configuration for good solution distribution and (5) avaHabHity of oxygen. 

Recovery of copper from solutions generated in heap/dump leaching with sulfuric acid by cementation with iron. 

Health R D (research and development) expenditures, 27 612 Health standards, at nuclear power facilities, 7 7 551-554 Health uses, for iodine, 74 372-373 Heap and dump leaching, 76 153 Heap leaching, 72 689-690, 699-700 76 128... 

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) ... 

Liddell, K. C., A Mathematical Model of the Chemistry of the Dump Leaching of Chalcopyrite, 1979, Ph.D. Thesis, Iowa State University, Ames, Iowa. 

It will be instructive to consider briefly the methodology employed in the development of solvent extraction processes that have become operational. The development of the Bluebird Mine operation for the extraction of copper from dump leaching liquors by solvent extraction and the subsequent recovery of copper as either copper sulfate or cathode copper is used as an example. The initial investigations [11] included the following ... 

In dump leaching of copper, it is not necessary to use extra stages of extraction to recover all the copper from the solution, since the raiSnate will be recycled to the dump. 

Figure 11.16 Schematic of copper recovery by coupled transport from dump leach streams. The concentrated copper solution produced by coupled transport separation of the dump leach liquid is sent to an electrolysis cell where copper sulfate is electrolyzed to copper metal and sulfuric acid...

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 increasing application of dump leaching can be attributed to the large tonnage of below-grade material accumulating every day, the relar-tively low capital outlay required to put a leaching and precipitation plant on stream, the small labor force required to operate the plant, and the simplicity of the operation itself. 

Eriksson, P.K., Lien, L.A., and Green, D.H., NanofllHation for removal of surplus water in dump leaching, Tailings Mine Waste 96, Proceedings of 3rd International Conference, 1996, p. 451. 

---