Waterproofing of mined-out voids during closure of potentially hazardous sites in potash mines

Closure of a mine or its part is one of the final phases in mineral mining. Methods of scheduled and controlled closure of a mine developing a deposit of water-soluble ore, such as a potash mine, are limited because of abundance of accidents induced by inrushes of fresh water in underground openings. The choice of a method to isolate a potash mine site from the other openings within the mine field depends on the geological and geotechnical conditions of mining. ‘Dry’ mechanized closure of a potash mine or its site takes much time and resources, much more than it is economically efficient and rational. ‘Wet’ controlled closure includes filling of a mined-out void of the potentially hazardous site with a liquid medium. Such medium in a salt mine can only be the mineralized brine which gradually fills the whole volume of the mined-out voids. Design of waterproof bulkheads is determined from the permeability studies of rock mass, and from the calculation of the structural parameters and properties of materials of the bulkheads, with regard to the required service life of the waterproof bulkheads, as well as the pressure and composition of the brine. The bulkheads should consist of props with waterproof segments arranged between them. The props are required to retain the waterproof segments in their preset positions, and to compensate stresses that appear in them. The waterproof segments eliminate seepage of brines through the body of a bulkhead and along its interface with rock mass. All engineering solutions on design and number of the waterproof bulkheads, and on materials selected for specific conditions are determined from the results of integrated scientific research.

Skopinov M. V. Waterproofing of mined-out voids during closure of potentially hazardous sites in potash mines. MIAB. Mining Inf. Anal. Bull. 2025;(4):59-71. [In Russ]. DOI: 10.25018/0236_1493_2025_4_0_59.

M.V. Skopinov, Director for Design, Director of Mining and Geological Research Section, VNII Galurgii, 614002, Perm, Russia, e-mail: Mihail.Skopinov@uralkali.com.

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