Ural State Mining University (Ekaterinburg, Russia):

Bagazaev V. K., Professor, Doctor of Engineering Sciences, e-mail: rmos.dep@ursmu.ru
Valiev N. G., Principal for Science, Professor, Doctor of Engineering Sciences
Apakashev R. A., Professor, Doctor of Chemical Sciences

Under consideration is mechanical strength and water impermeability of polyethylene film in the impervious screen at the bottom of gold heap leaching stockpile. The screen is designed for efficient gathering of leaching solution and ecological safety control owing to maximum waterproofing of the stockpile bottom. Construction standards for impervious installations made of polyethylene films involve a protective layer made of sandy soil. Theoretically, impervious screens made of polyethylene film are waterproof. However, under increased vertical load generated by a leaching mass, the protective layer is compacted, and shearing-off or forcing-through of the film is possible where two soil particles contact. Based on theoretical considerations and computations, the article gives relationships of the required thickness of polyethylene film by the conditions of cut and crumple versus the load applied to the underlying layer of the stockpile. Amount of potential leaks of leaching solution in the film damages is validated. The solution leaks through the film screen are calculated by analogy with the computation of industrial effluent flow in a hydroscopic hole. The article presents the calculating formulas and compares the calculated strength of the film with the standard values. Aiming at ecological safety and higher reliability of the calculations based on hydromechanical substantiation of strength and water impermeability of the polyethylene screen, it is recommended to estimate the required thickness of the film by the allowable tangential shearing stress and to calculate potential leaks of leaching solution by analogy with the calculation of water flow in a hydroscopic hole.

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