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.