Abstract:In order to solve the problem of the transition from the first mining area to the second mining area in Hequ open-pit mine,Three transition modes of mining area are proposed, namely, re trenching, retaining trench with gentle slope and sector turning. Based on the current mining situation of Hequ Open pit Mine, the advantages and disadvantages of the three connection modes of mining area are compared and analyzed, and the transition mode of retaining trench with gentle slope is finally determined, two methods of mining with full pressure and internal drainage and mining with full reserved ditch and internal drainage were adopted. Based on the comprehensive benefits of the two mining methods, and on the basis of comprehensively considering the requirements of the mining procedure in the second mining area of Hequ open-pit coal mine and the impact of ditch retention on the internal drainage transportation system, raw coal transportation system, and the change of transportation distance, this paper systematically reveals the comprehensive impact law of various ways of wall pressure and internal drainage on the stripping system, and seeks the best mining procedure of wall pressure and internal drainage in the total wall pressure and ditch retention internal drainage schemes, The secondary stripping and transportation costs of materials with different mining methods are calculated, and the total cost model is constructed. Through technical and economic comparison, It can be concluded that the transportation distance of stripped materials discharged inside the full pressure wall is small, and the inner drainage space can be completely released. Stripped materials do not need to be discharged outside, and can be completely discharged inside. The mining will lead to a large amount of secondary stripping of the western end wall that contacts the first mining area during the mining process of the second mining area. The economic benefit is poor, while the secondary stripping amount of the full ditch drainage mining is small, but due to the influence of the ditch, the inner drainage space cannot be completely released, The transfer cost of stripped materials is increased. Meanwhile, large area of land needs to be expropriated to discharge stripped materials, and the overall mining cost is high. Comprehensive comparison of the two mining methods shows that the full ditch drainage mining has better economic benefits, and is superior to the full pressure wall drainage mining.