Study on the Mechanism of Gas Ignition by Friction Effect of Hard Quartz Sandstone Instability

Figure 4

Process of hard sandstone friction spark inoculation and gas ignition.

(a) 0 s

(b) 1.217 s

(c) 2.817 s

(d) 4.650 s

(e) 4.667 s

(f) 4.867 s