Research on the amount of safely mineable coal in mines susceptible to coal and gas outburst

The concept of the amount of safely mineable coal was proposed to help with safety supervision during excavation in mines susceptible to coal and gas outburst. Relationships between the amount of safely mineable coal and 'three coal reserves' were studied. The results show that the amount of safely mineable coal is the non-outburst coal quantity in preparatory coal quantity and that it must have enough of a production period. For safe mining the quantity of mined coal must be less than the amount of safely mineable coal. This safely mineable coal includes about four fifths of the preparatory coal quantity and 2.3 times the mining coal quantity. The mineable periods of preparatory coal quantity, safety coal quantity and mining coal quantity are 16.6, 13.3 and 5.9 months, respectively. The practice at the Qinan mine is such that the amount of safely removable coal meets the requirements for normal relay and mining safety.