Allaying of coal dust by water infusion of coal in place in the leading coal producing countries of the world

Excessive coal dust created and released during mining operations in pillars and faces of entries in some bituminous-coal mines in the eastern and western parts of the United States was allayed effectively by applying the water-infusion, or water-infiltration, method. The infusion method consists of injecting water or a mixture of water and a wetting agent into coal pillars and faces of entries to abate dust, and to prevent the dispersion of small particles of dust normally created and released during subsequent operations of mining. Dust counts were reduced to within safe limits by applying the waterinfusion method in mine working places. In addition to reducing air-borne dust, water-infusion has been credited also with eliminating pillar heating and stopping one fire, thereby saving 700,000 tons of coal for uninterrupted mining operations. It was found that infiltration had important secondary advantages, as follows: 1 . It partially degassed the working faces and thus reduced the possibility of ignition during other mining operations. 2. It caused incipient fracture of the coal, with consequent easing of cutting and, to a lesser extent, blasting. The moisture added to the coal during infusion apparently had no effect on screening or on the marketing properties of the coal. Moisture was greatly reduced by evaporation during haulage. It was indicated that the water-infusion method could be adopted for dust suppression in coal beds with similar physical structures to those encountered In the Kenilworth, Lower Sunnyside, and Hiawatha coal beds in Utah; the Adaville coal bed in Wyoming; and the Beckley coal bed in West Virginia, Besides the nature of the coal bed, other important practical considerations affecting the application of the method were those of roof and floor; the location, spacing, and depth of the boreholes; and the pressure and rate of infusion of water or a mixture of water and wetting agent. The water-infusion system was adopted in the pillar areas and faces of entries in some mines and was merged into the regular cycle of mining operations. Because many of the leading coal-producing countries of the world have used the method quite extensively in some of their mines for several years, they have much more research data on the subject than we have in the United States. It is important to note that these countries claim excellent results in application of the water-infiltration method.