PREPARATION OF FROZEN ROCKS FOR EXCAVATION IN PLACER MINING IN TRANSBAIKAL REGION

The critical review of different methods for melting seasonally frozen and permafrost rocks is performed with presentation of advantages and disadvantages of natural solar radiation thawing. The ways of accelerating natural solar radiation thawing of frozen rocks during placer mining in severe climatic conditions of Transbaikalia are considered. Based on the implemented research, the procedure is developed for preparation of frozen rocks for excavation with high accuracy prediction of thawing parameters in frozen rock mass. Possible variants of using thermal bathtubs and, in particular, salt solar pool for preparation of frozen rocks for excavation are described. The operation principle of the salt solar pool is shown. The substantiation is provided for using thermal bathtubs with activation of heat exchange in the bottom layer of the salt solar pool, which allows considerable reduction in thermal energy loss in disintegration of frozen gold-bearing sands and loose overburden due to decreased evaporation of water from the pool surface and attenuated diffusion in its layers. Developed in order to lower loss of thermal energy from solar radiation, the patented methods of frozen rock thawing combine thermal bathtubs and needle–leakage thawing, which makes it possible to considerably cut down costs of water injection through needles to wells and to increase the rate of thawing of frozen rocks to 20 m/year. The implemented researches and calculations show that use of salt solar heaters accelerates thawing of frozen rocks, increases efficiency of solar energy up to 0.70–0.75, reduces period of preparing frozen rocks for excavation and in general brings down placer gold mining cost. The simulation modeling results prove usability and high efficiency salt solar pools as accumulators of thermal energy for activation of frozen rock thawing during placer gold mining by dredging or hydraulic excavation in Transbaikalia.

For citation: Subbotin YuV., Oveshnikov YuM., Avdeev PB. Preparation of frozen rocks for excavation in placer mining in Transbaikal region. Gornyy informatsionno-analiticheskiy byulleten'. 2019;3:125-133. [In Russ]. DOI: 10.25018/0236-1493-2019-03-0-125-133.

Keywords

Gold placer, heat exchange, seasonally frozen and permafrost rocks, preparation of frozen rocks for excavation, frozen rock thawing methods, salt solar pool.

Issue number: 3
Year: 2019
ISBN: 0236-1493
UDK: 622.271.1
DOI: 10.25018/0236-1493-2019-03-0-125-133
Authors: Subbotin Yu. V., Oveshnikova Yu. M., Avdeev P. B.

About authors: Yu.V. Subbotin, Doctor of Technical Sciences, Assistant Professor, Professor, Yu.M. Oveshnikov, Doctor of Technical Sciences, Professor, Head of Chair, P.B. Avdeev, Doctor of Technical Sciences, Professor, Dean of Mining Faculty, Transbaikal State University, 6720300, Chita, Russia, Corresponding author: Yu.V. Subbotin, e-mail: ogr_chitgu@mail.ru.

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