Polymetal Engineering JSC (Saint Petersburg, Russia):

Kovalev V. N., Head of Laboratory, PhD Eng, e-mail: kovalev@polymetal.spb.ru

Muslimov B. A., Director of Geotechnology

Klepikov A. S., Principal industrial engineer

The article deals with problems associated with heap leaching of gold in permafrost zones: calculation of heat-insulating bottom layer of ore stockpile to ensure required negative temperature in underlying subsoil to support the stockpile stability; determination of heat flow for allyear- round leaching; selection of optimal ore fragmentation size. For the heat calculations, a package of programs has been developed for mathematical modeling of an ore stockpile and description of heat exchange between the stockpile and air, heat exchange between the stockpile ore material and leaching solutions and the ice–liquid water phase change. The mathematical models are based on weather data on air temperature, wind velocity and snow cover thickness and the terrestrial radiation balance, as well as use observations over 2007–2011. The authors present the calculated thickness of the required heat-insulating bottom layer of an ore stockpile and various scenarios of heap leaching. The approaches to selecting optimum ore fragmentation size for heap leaching on adverse and remote terrains have been validated based on experimental research of heap leaching of different fragmentation size ore.

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