Method of dusting coal mine surfaces

Abstract

Foamed material composed of water and limestone or other mineral dust suspended in a pregenerated foam is applied to the surface of a mine. Dry limestone dust or mineral dust is blended with pregenerated foam or foam generated in situ to produce a mass of foamed material that is highly vesicular but that is cohesive enough to be sprayed as a foamed mass against mine wall surfaces and ceilings. The foamed material is applied with a spray device that allows it to adhere to the surfaces of the mine. In another embodiment a dry powder formulation containing limestone dust, dry powder foaming agent and an additive that promotes the production of gas which effervesces upon contact with water can be used. The dry powder formulation can be applied by mixing it with water during application or by applying it to a wet surface. The foamed material can be built to a thickness suitable for the prevention and suppression of fires caused by the ignition of coal dust and methane gas. Once applied, the low water content of the foamed material permits evaporation of the water, resulting in a dry mass of fine, poorly-cohesive, vesicular material that dusts readily.