... of 760°C, only melting, no fire, it will extinguish as soon as the grids left flame if it fire. C ... of water, the broken rids will float on the water during washing coal, easy to be wash out. D. Good ... When ourtside force act on one rib, the force will disperse to other ribs at the same time, reduce ... in coal mine as ceiling and shield, also can be used to protect laneway when mining coal. It must ...