龙首矿崩落法采场上下盘矿石贫损控制措施及现场工业试验

Measures for control of ore dilution and loss when caving mining on hanging and foot wall and site commercial test in Longshou Mine

龙首矿西二采区上部中段采用无底柱分段崩落法开采,矿体倾角变化较大,当矿体倾角较小时,在上下盘出现了较大的矿石贫损。通过理论分析发现,由于切割平巷位置过于靠近上盘围岩而导致上盘出现了较大的矿石贫化,又因退采不充分造成了下盘的矿石损失。根据分析结果提出在上盘确定切割平巷位置时,确保切割平巷顶板以上有10 m左右的矿石层高度,以减少废石的崩落量和放出量;对于下盘则应退采至矿体与上分段底板交界处,以充分回收矿石,同时还可通过在下盘切岩部位增大边孔角度、增大崩矿步距以及矿废分采分运和废石不出井等措施来进一步降低下盘矿石贫化和采矿成本。在1580 m分段开展了下盘补孔回收残留矿石工业试验,共补钻18排炮孔,回收矿石20456.5 t,创造的直接经济效益逾500万元,由此充分证明了上下盘矿石贫损控制措施的可行性和有效性。

The sublevel caving method without sill pillar was applied to ore extraction on the upper mining levels of the No.2 west mining zone in Longshou mine where the dip angle of the ore body varied greatly,big ore dilution and loss presented in case of the small dip angle.From theoretical study,it can be found that the cutting drift way located too closely to the surrounding rock resulted in a large ore dilution of the hanging wall while the big ore loss in the foot wall was caused by insufficient retreating.According to the analysis,it is recommended that the cutting drift way in the hanging wall should be located with an ore layer of about 10 m thick above the roof of the cutting drift way so as to reduce the volume of waste rock to be caved and drawn.For the foot wall,the retreat mining should be proceed to the junction of the ore body with the floor of upper mining level,so that the ore can be recovered completely,moreover,for further reduction of ore dilution and mining cost,the side hole angle and the independent advance of ore breaking are to be enlarged,the ore and waste rock are extracted and transported separately.The waste rock is not expected to be delivered to the ground surface.The site commercial test was carried out at mining level of 1580 m by working out the additional 18 rows of blasting holes for recovery of the ore left over,which totaled 20,456.5 tons.As a result,the direct economic benefit of over 5 million yuan was achieved,which fully proved that the control of ore dilution and loss in the hanging and foot wall was feasible and effective.