Impact of the distance between the draw holes on the ore loss due to congealing during ore drawing

The paper considers the results of experimental studies of changes in the ore losses caused by congealing in the stoping zone during the drawing process in conditions of subzero temperatures in underground mining of eore deposits in the cryolithic zone, depending on the distance between the draw holes. Three series of experiments were performed using trench-shaped test benches with various distances betwen the draw holes. The distances between the access crosscuts were assumed to be 180, 200 and 220 mm, which is equal to 9, 10 and 11 m in actual conditions according to the adopted geometric scale of modeling. The results of modeling the bottom drawing in conditions of subzero temperatures, similar to the conditions of the underground ore mining in the cryolithic zone, showed that changes in the distance between the draw holes with the trench-shaped design of the bottom block have a significant impact on the extraction rates. When the distance between the draw holes is increased from 9 m to 11 m, the ore loss due to congealing during the draw phase rises from 24% to 42%. Experimental studies have shown that the increased distance between the draw holes in conditions of subzero temperatures in the bottom area leads to increased ore losses caused by congealing in the stoping area.