Using Proximate Analysis to Characterize Airborne Dust Generation from Bituminous Coals

Abstract

The amount of airborne respirable dust generated from breakage of different coals varies widely. This research was conducted to identify the facets of airborne respirable dust liberation from the coal product. Laboratory crushing experiments were conducted on a range of low to high volatile bituminous coals to investigate the various factors in uencing airborne respirable dust generation. Bituminous coal samples from 8 mines (5 U.S. and 3 Polish) were uniformly prepared and processed through a double roll crusher located in a low air velocity wind tunnel. Experimental factors studied included inherent coal seam constituents, speci c energy of crushing, product size characteristics, dust cloud electrostatic eld, and speci c quantity of airborne respirable dust generated.The results of this investigation build upon previously published results, which indicated that a combination of several factors are associated with the generation of airborne respirable dust. One factor involved is the effect of coal rank, described by the inherent moist fuel ratio, on the product size characteristics, de ned by Schuhmann size function parameters. However, since coals of high moist fuel ratio (high rank) are generally more extensively cleated, it is suggested in the present work that the degree of cleating is directly responsible for the quantity of respirable-sized particles produced in the crushed product material for eastern U.S. coals. This is implied by the relationship of ash content and at least one mineral constituent (pyrite, determined from pyritic sulfur analysis) to the percentage of airborne respirable dust. To validate this hypothesis, a description is offered that is based on known coal petrography.Another key factor is the effect of air dry loss moisture in the coal seam on the breakage-induced electrostatic eld of airborne dust. The air dry loss moisture factor appears to control the amount of airborne respirable dust that is liberated from the product. The resultant effect of these factors is that different percentages of coal particles smaller than 10 ¹m are dispersed as airborne respirable dust, with a well-de ned peak in the normalized airborne respirable dust for a narrow range of air dry loss moisture ¥ ash ratios. A clear delineation of coals, based on well-known proximate analysis characteristics, that generate the most respirable dust appears to be possible. It was also shown that the dust-generating characteristics of coals could be reasonably described by both the moist fuel ratio

Technologies for laboratory generation of dust from geological materials

“…An automated, stepper-motor controlled dry dust generator [80] has been used for epidemiological studies and as one of many ways to simulate dust aerosol exposures for inhalation toxicology laboratory experiments [81][82][83]. Wind tunnels, which are widely used to study the geophysical and micrometeorological aspects of aeolian processes, have also been used as dust aerosol generators [84][85][86][87][88][89][90][91][92]. Wind tunnels can recreate the saltation process [27,86], and are thus particularly well adapted to simulate wind erosion of soils and sediments.…”