Dust Prevention with Deep Borehole Water Injection and Spalling Prevention with Grouting in Unstable Seam with Soft Roof, Coal and Floor

In order to reduce the high coal dust density and serious coal wall spalling in the fully mechanized top coal caving mining face, according to the seam co nditions with soft roof, coal and floor in Baiping Mine, the deep borehole water injection for dust control and the grouting for the coal wall reinforcement were conducted in the seam of the coal mining face ZDY-3200 dilling rig was firstly applied to dril a water borehole with a depth of 60~80 m.ZBQ-6/2.5 mode drilling rig was applied ab out 6 m near the water injection borehole to drill a grouting borehole on the coal wall with a depth of 9 m.The MRB125/31.5 mode water injection pump was applied to t he seam hydraulic fracturing with a pressure of 12~ 14 MPa and after the seam fracturing, an intermittent water injection with a pressure of 5~8 MPa were repeatedly co nducted.The site application effect showed that the technology applied could make the seam water content increased from 4% to 5%~6% and the average dust content i n the air returning gateway was reduced from 269 mg/m3 to 108 mg/m3. The coal wall spalling scope of the coal mining face was reduced from 50%~70% to 10%~30% and the spalling problem was effectively controlled.