Abstract:During the process of open-pit to underground mining in Chang''an gold mine, the bottomless column segmental crumbling method is used, the problem of difficult formation of overburden layer, and the physical and mechanical properties of the site ore rocks are similar, more difficult to distinguish, and making ore loss depletion is not easy to control. To the end, three experimental schemes were designed to carry out indoor release experiments for three segments with different ore output and depletion rates, to optimize the release scheme, and to propose a quantitative control method. The experimental results show that the apparent recovery rate and poor recovery difference of Scheme 1 are higher than those of Scheme 2; the thickness of the ore bedding left by it is the largest, and the waste rock mixing rate and ore depletion rate are lower than those of Scheme 2 and Scheme 3, and Scheme 1 is the optimal scheme in a comprehensive analysis. The first mining section out of control is conducive to maintaining a uniform descent of the ore rock interface, which can effectively alleviate the problem of insufficient overburden thickness. The analysis of the second section of Option 1 shows that the ore release controlled at 65%-70% can effectively reduce the ore depletion rate; combined with the variation equation of current grade and current depletion rate of ore with the ore release, the method of quantifying the ore release control accordingly to effectively reduce the ore loss depletion is proposed. The experimental results were practically applied in each mining site of 1 518 m, 1 509 m, and 1 500 m sections of Chang''an gold mine, with good results, which have reference significance for similar mines.