Research into balance of rocks and underground cavities formation in the coal mine flowsheet when mining thin seams

Abstract

Purpose. Study the movement of waste rock flows in the coal mine technological system and determine the balance of rocks and underground cavities formation from the perspective of the current mining operations development in order to assess the possibility of leaving the rock in the underground area. Methods. Based on the rank order of the Western Donbass mines, a coal mine has been chosen as the object of research in terms of maximum output and ash content. An algorithm is proposed for analytical studies of determining the rock outcrop in the course of stope, drifting and repair operations, as well as the prospective volumes of underground cavities for placing the formed waste rocks per a calendar year. The algorithm is based on the actual state of mining operations and the indicators of the stope and drifting faces of the mine, as well as the achieved modern mining-engineering parameters of the coal seams mining. Findings. It has been revealed that the main supply of waste rocks to the surface occurs as a result of stope operations with rock undercut -39% and underground mine workings -33%. It is proposed to differentiate all waste rock outcropped after mining operations into 2 categories: difficult to dispose of and prospective for disposal. It has been found that underground cavities have enormous potential for stockpiling of all waste rocks, the volume of which is by 2.8-4.8 times higher than the rock volume. It has been revealed that the most rational balance of waste rocks and cavities for leaving the rock in the mine is formed along the С 10 t seam. It has been determined that the full-fledged placement of rocks is limited by the scheduling peculiarities of mining the reserves along the seams, which are made for the complete cave-in technology of coal mining. Originality. For the first time, for one of the Western Donbass mines, the balance of formed waste rocks and potential underground cavities, dynamically changing in time and space, has been determined. Practical implications. The results obtained are useful for engineering new spatial planning solutions for the optimal development of mining operations with the maximum possible rocks stockpiling in the underground area of mines.

Influence of waste rock dump placement on the geomechanical state of underground mine workings

“…In previous works, the influence of mine waste rock dumps on environmental components [17][18][19], the rational placement of dumps taking into account the migration of pollutants [20,21], the stability of slopes of bulk waste rock dumps [22][23][24][25], the sources of mine waste rock formation on the surface [26][27][28] have been studied. In addition, concepts and strategies for large-scale processing of mine waste rock dumps and tailings have been developed [29][30][31].…”

Enhancement of the rock mass quality in underground iron ore mining through application of resource-saving technologies

“…The authors have proposed selective mining of complex-structured ore deposits by a system with caving ore and overlying rocks [42][43][44][45][46][47]. The idea behind the option consists in mining the ore deposit in stages: I -extraction of ore reserves located between the hanging wall and the barren inclusion with its further drawing; II -drilling off the barren inclusion and moving it towards the hanging wall by blasting; III -breaking and drawing the remainder of ore on the footwall.…”

Enhancement of the quality of marketable iron ore products of Kryvyi Rih iron ore basin

“…Practice shows that the smaller the size of ore lumps is, the faster iron is recovered from ore. However, there is a size limit, because dense caking of fine ore impairs reducing gas permeability [16,26,34,[38][39][40][41][42][43][44][45]. The maximum size of an ore lump is usually accepted equal to 50-80 mm, the minimum one is 6-10 mm.…”