Abstract: After years of mining, the mining method in Miyun iron mine is changing from open-pit mining to underground mining. And in this process, sublevel rock drilling and stage room stoping method is used to take the ore in the pit outline. After its completeness, a vacant place about 52 500 m3 will be to take shape. Besides, a lot of pillars will be leaved behind and the ore in those pillars will be more than 400 000 tons. As time past, the earth pressure is increasing all the time and some pillars have collapsed. So impact earth pressure will happen at any time. Pillarless sublevel caving method will be used under the pit outline, so it is needed to deal with the vacant place and recycle the pillars before its beginning. Based on the problem of recycling of Pillars after sublevel rock drilling and stage room stoping in Miyun iron ore, it involves the recycling method, the blasting method and the recycling sequence and all the pillars have been recycled by this method successfully.

Key words: Pillar recycle, Vacant place, Open stope method, Sublevel caving method, Millisecond blasting