新城金矿阶段空场嗣后充填法开采大直径深孔切槽爆破方法

Large Diameter Long Hole Cutoff Slot Blasting Method for Sublevel Open Stoping with Delayed Filling in Xincheng Gold Mine

在阶段空场嗣后充填法开采过程中,如何形成回采爆破的初始补偿空间是成功应用该采矿方法的关键。阶段空场嗣后充填法在进行切割拉槽爆破时,受到围岩的夹制作用,极易造成切割槽爆破欠挖甚至出现爆破失败的问题。以新城金矿为工程背景,采用无切割井大直径深孔爆破方法形成切割槽。对比分析传统的垂直深孔后退式分段爆破拉槽方法与“品”字形后退式分段爆破拉槽方法,结果表明:当采用“品”字形后退式分段爆破拉槽方法时,既利用了采场下部的自由空间,又利用了由于“品”字形布置所创造的超前自由面和中央补偿空间,可以显著提升无切割井深孔爆破的效果。在此基础上,优化了新城金矿阶段充填法开采过程中大直径深孔切槽爆破的孔网参数。综合分析结果,确定了新城金矿大直径深孔切槽爆破一次爆破高度为3.6 m,炮孔直径为100 mm,炮孔的排间距和孔间距均为1.5 m,爆破边孔距离爆破边界为0.5 m,并在切割槽中央设置4个空间补偿孔,改善“品”字形后退式深孔切槽爆破的效果。

The sublevel open stoping with delayed filling mining method has the advantages of large production capacity,high efficiency and low cost,and it is widely used in underground metal mines.However,at the same time,this method has a large amount of blasting charge and poor flexibility in application of the method,which puts forward higher requirements for blasting control.In particular,the cutoff slot blasting to provide the initial free surface and the blasting compensation space for the mining blasting is more important for the successful application of this method.When this type of mining method is used for cutoff slot blasting,it is easily confinement by surrounding rock,which can easily lead to over blasting and under blasting of cutoff slot,or even failure of cutoff slot blasting.The traditional long hole VCR method for cutoff slot blasting is limited by the blasting free surface,and the blasting effect is difficult to guarantee.In view of this problem,this paper taked Xincheng gold mine as the engineering background,analyzed the existing problems of traditional long hole VCR method for cutoff slot blasting,and proposed a new method for large-diameter long hole cutoff slot blasting method without cutting wells.Based on Livingston’s blasting filler theory,combined with the current production experience,the blast hole diameter,hole arrangement parameters,explosive unit consumption,primary blasting height,charge and packing parameters for large-diameter deep hole cutoff slot blasting were calculated.The traditional vertical deep hole retreat blasting method and the“Pin”-shaped retreat blasting method were compared and analyzed.The results show that when the“Pin”-shaped retreat blasting method is adopted,not only the free space in the lower part of the stope is used,but also the advanced free surface andcompensation space created in the center due to the“Pin”-shaped layout,which can significantly improve theeffect of deep hole blasting without cutoff well.At the same time,in order to improve the blasting effect of thecentral cut blasting hole,four blasting space compensation blasting holes are set between the blasting holes.Based on the above analysis results,a field industrial test was carried out in the -380 m sublevel of Xinchenggold mine.The blasting height is 3~6 m,the blast hole diameter is 100 mm,the row spacing and hole spacing ofthe blasting holes are 1.5 m respectively,the distance between the blasting side holes and the blasting boundaryis 0.5 m,and the distance of space compensation hole and the blasting hole is 1.0 m,and the thickness of theblasting top is 6.75~12.75 m in the large-diameter deep hole cutoff slot blasting of Xincheng gold mine.Thefield industrial test results show that the designed caving amount of cutting slot is 4 105 t,the actual ore cavingamount is 4 300 t,and the unit explosive consumption is 0.85 kg/t.The shape and size of the open stoping afterblasting meet the blasting design requirements.