31号矿柱的回采计划9号矿体的二次回采计划是以17号矿柱为永久矿柱,将待回采的矿柱以17号矿柱为界,划分为南北两部分,各自独立地平行进行回采。17号矿柱以北部分正以分段崩落法回采;17号矿柱以南的22号、28号、31号等大型矿柱尚未回采。 No.31 ore pillar recovery plan The No.9 orebody secondary recovery plan is based on the 17th pillar as a permanent pillar, the pillar to be recovered to 17 pillar as the boundary, divided into two parts north and south, each independently Parallel mining. The north part of No. 17 ore pillar is being reclaimed by subsided caving method. Large ore pillars 22, 28 and 31 south of No. 17 ore pillar have not yet been recovered.