Abstract: The actual air volume of the ventilation system of a large openpit to underground mine is much lower than the design air volume,and the air leakage volume at the subsidence area of caving mining reaches 90.69 m3/s,accounting for 25.33% of the total air volume of the mine.In order to solve the problems existing in the mine ventilation system,a reasonable analysis and optimization of the mine ventilation system are carried out by using multilevel machine station technology.The West No.5 return air shaft was added as the return air road in the west mining area,and the two fans on the surface of the 2# return air shaft were replaced with 250 kW fans,which increased the total air volume of the mine while increasing the return air volume in the west mining area.A comprehensive investigation of air leakage points in the collapsed area within the entire mine was carried out,and ventilation structures were used to seal multiple air leakage points,such as 0 m horizontal tubing and cable shafts,mining roadways and auxiliary shaft gates,to solve the problem of air leakage in the subsidence area and increase the effective air volume rate of the mine effectively.By implementing optimization measures,the total mine air volume has been increased to 513.64 m3/s,and the mine air leakage rate has been reduced to a reasonable range below 5%,effectively improving the comprehensive utilization rate of mine ventilation energy consumption.

Key words: ventilation system,multilevel station,air leakage rate,effective air volume rate