Suspended roof forms in the ore extraction process in Sifang Gold Mine,which reduces the ore extrac-tion rate.Based on the measurement data from field investigation,layouts of medium long hole blasting design,con-struction status and charge structure,the suspended roof formation during the ore extraction process was analyzed and the results suggested that the main reasons included sublevel overheight,unreasonable design parameters for medium long hole blasting,over high deviation rate for medium long hole blasting,unplugged borehole and insufficient compen-sation space.The existing suspended roof is extracted by drilling downward boreholes from the upper sublevel ap-proach.The subsequent suspended roof should be avoided by improving blasting performance,the measures including making strict quality acceptance requirements for medium long hole drilling,enhancing measurement and medium long hole design,and applying reasonable charge structure and hole-plugging methods.%四方金矿在矿石回采过程中存在悬顶现象,降低了采矿回收率.通过现场调查测量数据、中深孔设计图纸、施工情况及装药结构等,对矿山回采过程中悬顶产生的原因进行分析,其主要原因包括分段高度过高,中深孔设计参数不合理,中深孔偏斜率过大,炮孔不堵塞,补偿空间不足等.针对现有悬顶采取上部进路钻凿下向孔的处理方式,对后续悬顶的预防应加强中深孔施工质量验收,强化测量与中深孔设计工作,采用合理的装药结构和堵孔方式等以改善爆破效果.
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