| Fully mechanized caving mining technology is a kind of mining method developed for thick seam mining.From the development trend,fully mechanized caving mining should be preferred when mining 3.5m~6m unstable thick seam and 6m~14m stable or unstable extra-thick seam.However,due to the fracturing effect of mine pressure on top coal,the existing research and experimental results show that under the condition of mining depth less than 100 m,it is not appropriate to adopt fully mechanized top coal caving mining technology.For example,the coal seam conditions are suitable to adopt fully mechanized top coal caving technology,technical measures to weaken top coal and improve the top coal caving rate must be matched.Firstly,the average thickness of 16# coal seam in Gongwusu area is 8.86 m,which is suitable for fully mechanized caving mining.But because the average depth of 16# coal seam is only 103 m,which belongs to shallow deep coal seam,and the overlying stratum is soft,the overlying stratum is cut off above the coal wall during mining,and the front square of the working face can not form the pre-supporting pressure of fractured top coal.The top coal caving rate using traditional fully mechanized caving technology is relatively low.At present,with high production and high efficiency,it is necessary to take technical measures to weaken the top coal and improve the top coal yield.Secondly,according to the general principle of improving the top coal caving rate in fully mechanized caving face,appropriate top coal pretreatment measures should be taken according to the coal seam occurrence conditions in order to maximize the top coal caving rate.The 16# coal seam in Gongwusu area has the characteristics of shallow buried depth and soft overburden,and technical measures with universal popularization value should be taken in view of this feature.Finally,Lutian Coal Mine in this area has implemented a number of valuable technical measures: using the reasonable matching technology of fracture orientation,thatis,adopting the measures of reasonable matching of the fracture orientation of coal seam and the advancing direction of working face,in order to maximize the degree of top coal rupture;developing the auxiliary coal breaking device with hydraulic support,that is,installing the top of the traditional fully mechanized caving hydraulic support along the advancing direction of working face.Loading two triangular coal-breaking plates,loosening the broken top coal by extrusion mechanical force,improving the top coal caving rate;using the technology of repeated pushing extrusion and loosening coal-breaking by support,i.e.using hydraulic support with auxiliary coal-breaking device to implement one or two times pushing extrusion,improving the broken degree of top coal,maximizing the effect of top coal fracturing;determining reasonable mining parameters,i.e.optimizing fully mechanized top coal caving work The mining height at the bottom of the face,roof control distance,support resistance,cutting depth and caving step can improve the damage degree of top coal,thereby improving the top coal caving rate.The comprehensive implementation of the above technical measures can increase the coal recovery rate of fully mechanized caving technology under the condition of shallow buried deep soft overburden to more than 80%,the maximum can reach 91%,and the technical,economic and social benefits are good.In the process of research,due to limited conditions,the technology of water injection weakening top coal has not been studied comprehensively.Therefore,it is suggested that Lutian Coal Mine in this area carry out the research of pre-water injection weakening top coal technology,and form more perfect supporting technical measures. |
