Scientific and Production Association “RIVS”, Saint Petersburg, Russia:

V. S. Trubilov, Head of Geotechnology Department
A. S. Klepikov, Leading Engineer of Hydrometallurgy Department, e-mail: A_klepikov@rivs.ru

Overwhelming majority of mining and processing plants in Russia and abroad use technologies that had been developed for rich and mediumrich base metal ores. As it is, the raw material base is being depleted, which makes mineral processing increasingly less efficient and profitable. For example, the copper content of ore will reduce to 0.5% in the nearest future. Considering the reality, downstage come technologies capable of minimum cost treatment of low grade raw material and nonstandard oxidized ore that previously were not processed but dumped, or not even mined. Such technologies are dump and heap leaching successfully used in some countries for many years already. Having a common framework, these two methods differ in implementation and the choice of a method should be based upon meeting three essential requirements simultaneously:
- seat of a dump are water-resisting rocks, impermeable for solutions;
-in-situ ore material of dumps possesses sufficient permeability for process solutions;
- recovery ratio of useful component (metal) from in-situ mine waste ensures economic efficiency of the project.
Given the three requirements are satisfied, the dump leaching technology is feasible. A single condition violated, the heap leaching is implemented. Mine dumps are the source of long-term contamination of surface and subsurface water due to emission of salts of base and heavy metals. Leaching allows handling this problem by intensifying emission and removal of metals and their salts with the impregnation solution. By way of illustration, an extended cost analysis has been performed for a copper leaching site at Kalmakyr mine dump. The analysis displays economic expediency of the leaching technology.

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