Principal Technology Study On Pillor Mining Under The System Of Room And Pillor Mining

Lots of coal mines in neimenggu use the system of room and pillar and exploits only rooms but not pillars. Probably 6.6～7.0 billion t coal was discarded under mine and formed slacken coal. Slacken coal was to proceed spontaneous combustion in the course of long oxidation and caused environment pollution. At the same, it caused great waste to nation precious resources. So pillar extraction is a problem to be solved presently. The subject was put forward in this case.The text takes taifeng coal mine for example, analyzing the influence to pillar mining because of the dimension of room and pillar, then discussing the stability and controllability about advanced pillars. The text models advanced pillars in mining field with the software UDEC3.1, at last the text does some research on the support in pillars' mining field and the method of pillar extraction. The text draws some conclusions: initial dimension of room will influence pillar minin. the failure form of advanced pillars (shear failure and compression failure) was given through analyzing the stability of advanced pillars, and the text gives shearfailure criterion F ≥ τ_max. The text concludes that we can protect advanced pillars from shearfailure by controlling coefficient of volumetric expansion of mining field rock and from compression failure by advanced support, increasing setting pressure and working resistance. The text obtains some data that caving span of immediate roof is 30m, caving span of main roof at first weighting is 42m and caving span of main roof at periodic weighting is 14m. Mining influence range is determined about 40m through numerical modeling, namely about three advance pillars were in the range of mining influence. Pillar mining was carried by yielding pillars and its action is to decrease the rotation of main roof, avoiding pillars' shear failure, forecasting the weighting of main roof as signal pillar and support enough time for moving supports. The method of coal cutting adopts deep-hole blasting and realizes no people in the face, this decreases risk when workers are working in the face. Pipe effect was overcome in deep-hole blasting with blasting ;fuse whose speed is 6900m/s to ignite nitroamino chare. GXMZJ boring machine (which can realize correct positioning in the...