Recovery of compaction resources in internal dump of gently inclined composite coal seam open-pit mine

In the production and construction process of a slowly inclined composite coal seam surface mine in China, the problem of coal compression by the non-working slope is common, but the research on coal recovery is usually conducted for the end slope compression problem. Due to the small economic and reasonable stripping ratio in the early stage of infrastructure construction in an open-pit mine, the buried deep coal seam has not yet been mined and is covered by internal dumping. In recent years, with the gradual increase of the economic and reasonable stripping ratio, the mining of coal seam covered by internal dumping site has become feasible. This paper puts forward the mining scheme for this problem. In this paper, a mathematical model is established, and the trench between the inner dump and the non-working side is used as the working platform for coal seam mining. The relationship between stripping height, working line length and mining width of coal seam is studied. The variation law of production stripping ratio, remining amount, repeated stripping amount and mining width is further analyzed. At the same time, the influence of production stripping cost on the economic and reasonable stripping ratio is studied, and the relationship between transportation cost and discharge distance is established, so as to indirectly determine the relationship between mining width and economic and reasonable stripping ratio. Finally, it is found that the relationship between mining net income and mining width is first proportional and then inversely proportional. Taking an open-pit mine as an example, through the quantitative analysis of economic indicators, the net income of coal mining under different mining widths is calculated. The results show that when the mining width is 271 m, the economic benefit of the inner row mining is the highest, and the net income reaches 2021.4575 million yuan. At this time, the production stripping ratio is 5.25, which is less than the economic and reasonable stripping ratio of 6.95. The practical significance of the results is to improve the overall economic benefits and recovery rate of mining enterprises, and ensure the safe, green and efficient mining of mines.