... blast and block of all kinds of silo, hopper, cement preheating furnace, pipeline Y section and mine ... material such as fertilizer, concrete, foundry sand, small loading gate, small RC silo and so on.Air ... material tend to harden such as various middle-size loading coal silo, raw coal silo with big capacity ... vertical wall of the silo and the conical hopper up to the lower part, therefore we should ...