Substantiation of the possibility of developing reserves of the Third potash horizon of the Starobin deposit, previously worked out by the chamber system
A technique has been developed of justification of possibility and expediency of extraction of the reserves left, which were mined more than 40 years ago by chamber system with maintenance in a safe condition of underground mining constructions. The methodology includes the identification by studying the geological and mine surveying documentation of districts with reserves in the mine fields; calculation of volumes and quality indicators of reserves left at these areas; assessment of a condition of mine workings that have direct access to the reserves concerned, and the possibility of their re-use, as well as the possibility of new development workings and ensuring their sustainability and maintenance in a safe condition; establishing the features of geomechanical processes in the rock mass and the presence of dangerous violations in the worked-out zone, the degree of the violation and the nature of the deformation of rigid and pliable pillars in the extraction chambers, including the use of specially conducted mine openings; development of technological schemes for safety extraction of abandoned minerals. With the use of this technique for the first time the technological opportunities and economic feasibility of mining minerals from the treatment units of the First and Second Mines of JSC Belaruskali, worked out more than 40 years ago, has been estimated. The possibility of excavating abandoned reserves in the sylvinite layer 4 and layers 2, 2–3, 3 in inter-chamber pillars in areas previously worked out by the chamber system with total volumes of more than 57 million tons is shown. The results of surveys of the state of capital and development workings are given, according to which for the re-mining of most of the worked-out blocks, new capital and development workings will be required. The results of visual examinations of panel and block drifts, their conjugations with treatment passages, as well as the state and degree of violation of inter-passage and inter-chamber pillars in the treatment chambers are described. Possible methods for re-mining the reserves of the Third potash horizon with treatment longwalls and a chamber system are proposed, which are distinguished by high technical and economic efficiency and mining safety.