地下铝土矿破碎岩体高效爆破技术研究

Study on high efficiency blasting technology of fractured rock mass in underground bauxite mine

山西省地下铝土矿为缓倾斜薄矿体,岩石坚硬但岩体破碎,直接黏土岩顶板受爆破冲击影响较大,导致掘进效率低、爆破进尺短,增加了顶板失稳的安全风险。本文通过未确知测度模型评价分析铝土矿可爆性等级为Ⅳ级,为爆破设计及直眼掏槽抛掷方案提供支撑,提出中心双空孔超深滞后抛掷直眼掏槽和光面爆破技术,通过现场爆破试验,断面3m×2.5m、炮孔深度2.1m时,有效进尺>1.85m,单进尺长度提高约0.25m,炸药单耗由0.73kg/t降至0.6kg/t,单进尺炮孔数减少2个,爆破块度均匀,爆破后顶板平整。

The underground bauxite in Shanxi province is a thin ore body with gentle slope.The rock is hard but the mass is broken.The clay rock direct roof is greatly affected by blasting shock.The blasting efficiency is low and the advance of drilling footage is short that increases the safety risk of roof instability.Through the analysis of the unascertained measurement model,the blast-ability of bauxite rock mass is Ⅳ level.It provides support for the blasting design and the throwing scheme of vertical hole cutting.The technologies of vertical hole cut of deeper delayed projectile with central double cavity and smooth blasting are proposed.Through field blasting test,3 m×2.5 m tunnel section with 2.1 m depth holes,mean effective penetration is >1.85 m.Single footage length is increased by about 0.25 m.Specific charge is reduced from 0.73 kg/t to 0.6 kg/t.Two blasting holes are reduced in every single footage.The rock fragmentation is uniform and the roof is flat after blasting.