Bulletin . as required in screening. The float dust was eliminatedby stirring small portions of the screened size in a deep pail, withthe end of a hose discharging compressed air. By this means eachsize when finally finished was remarkably clean and free from othersizes. 44 THE EXPLOSIBILITY OF COAL DUST. DISTRIBUTION OF DUST. In this series of experiments, the dust of the size to be tried wasdistributed along the gallery on four aarrow iron shelves on eitherside. The gross amount distributed was 1 pound per linear foot ofgallery. This amount is much in excess of what is necessary toproduce an
Bulletin . as required in screening. The float dust was eliminatedby stirring small portions of the screened size in a deep pail, withthe end of a hose discharging compressed air. By this means eachsize when finally finished was remarkably clean and free from othersizes. 44 THE EXPLOSIBILITY OF COAL DUST. DISTRIBUTION OF DUST. In this series of experiments, the dust of the size to be tried wasdistributed along the gallery on four aarrow iron shelves on eitherside. The gross amount distributed was 1 pound per linear foot ofgallery. This amount is much in excess of what is necessary toproduce an explosion, so that only a relatively small part of the dustis active or loses its volatile matter. In addition to the dust placedas just described, 20 pounds was placed upon a horse 20 feet long and9 inches below the center line of the bore hole and the axis of the gal-lery. The dust was placed in this way to obtain the most extremecondition, such as would be found in a mine with a blown-out shot Bore hole. Koerfingexhauster Window ^53 LONGITUDINAL SECTION 0 5 10 Feeti i 1—i—i—i 1 Figure 1.—Diagrammatic sections of cannon end of gallery No. 1, Pittsburg station. pointed toward a pile of coal dust. Figure 1 is a sectional outlineof part of the gallery, showing the location of the horse. DISCUSSION OF RESULTS. In the first tests a charge of 1^ pounds of black powder was used,tamped with 2J pouncte of clay. With this charge dusts larger than60-mesh did not even ignite (except for slight prolongation of powderflame in tests 1 and 2), but 80 to 100 mesh dusts and also 60 to 80mesh dusts in three out of four tests did ignite and propagate theexplosion. It may be assumed that finer sizes would propagate, sono tests were made of them. A series was then tried with double the quantity of black powder,or 2\ pounds, and with 2 pounds of clay stemming, which was all thatthe depth of the bore hole would allow. The effect was notable; 60 to80 mesh dust propagated the explosion and so
Size: 2235px × 1119px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
