John A. Organiscak

Semi-Empirical Model for Predicting Surface Coal Mine Drill Respirable Dust Emissions

Over exposure to airborne respirable crystalline silica dust can cause serious or fatal respiratory disease and mine worker exposure to silica dust continues to be an ongoing occupational health concern. Exposures of surface coal mine rock drillers to respirable crystalline silica are of particular concern. MSHA dust exposure data from 1985–1992 showed that the percentage of the highwall drill dust samples (Designated Work Position, DWP) having greater than 5 percent silica and exceeding the 100 µg/m 3 silica limit were 81 percent and 77 percent, respectively. Although a recent analysis of the MSHA data from 1996–2000 shows that the percentage of the DWP drill dust samples exceeding the permissible exposure limit has dropped to 31 percent, MSHA data still suggests that over exposure to silica dust is an ongoing surface coal mine dust problem for the highwall drill operator. On surface coal mine drills, bailing airflow flushes out the drill hole by removing the cuttings from the hole. Conveyor belting material is typically used to fabricate a shroud around the drill deck in an effort to contain the drill dust so that it can be captured by a collector. Dust leakage from the drill shroud is usually the worst dust source problem on most drills. The focus of this work is drill shroud dust leakage and the relationships of various drilling parameters on this leakage. Experimental data was obtained and used in combination with dimensional analysis to establish these relationships. In general, it is found that airborne respirable dust concentrations vary in a direct relationship with shroud leakage area and in an inverse relationship with drill deck cross-sectional area and shroud height.

Development of a dust collector inlet hood for enhanced surface mine drill dust capture

Surface mine drill operators have the highest frequency of overexposure to quartz dust, and drilling is one of the occupations associated with the highest incidence of silicosis. Previous field assessment studies of drilling machines indicate that they can emit some of the highest airborne respirable quartz dust concentrations found at surface mining operations. Typically, the surface mine drills are equipped with dry dust collector systems to capture the dust being flushed with compressed air from the hole during the drilling process. The overall control effectiveness of the dust collector system is initially dependent on capturing the dust cloud at the source via the collector inlet. To assist the initial capture of the dust being flushed from the drill hole, the bottom of the drill deck is typically shrouded or enclosed on all sides to help contain the dust for the collector inlet plenum located on the underside perimeter of the drill deck. Openings, gaps and breaches in the shroud enclosure permit dust to escape dust collector capture. 1 Mention of any company name or product does not constitute endorsement by the National Institute for Occupational Safety and Health. The National Institute for Occupational Safety and Health (NIOSH) has developed a collector inlet hood that reconfigures the inlet plenum around the drill steel and above the hole to enhance dust capture. Laboratory development and testing show that this inlet hood improves dust capture by an average of nearly 50% over a wide range of collector flows and shroud leakage areas. This report describes the laboratory and subsequent field testing of this inlet hood concept.

Using Proximate Analysis to Characterize Airborne Dust Generation from Bituminous Coals

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 influencing 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, specific energy of crushing, product size characteristics, dust cloud electrostatic field, and specific 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, defined 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 field 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 w m are dispersed as airborne respirable dust, with a well-defined peak in the normalized airborne respirable dust for a narrow range of air dry loss moisture 1 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 and the Hardgrove Grindability Index (HGI). These results show a clear distinction between eastern and western U.S. coals. However, no consistent distinction for Polish coal was observed.

The Effects Of Low Quartz Mass Loading And Spatial Variability On The Quartz Analysis Of Surface Coal Mine Dust Samples

Monitoring the miner respirable quartz dust exposure for compliance with U.S. federal regulations is mandatory to protect the health of coal miners. However, there is no technique available for the direct measurement of the respirable quartz dust concentration in the mining environment. The only means to estimate the respirable quartz dust concentration is to perform an analysis of the respirable dust sample collected, which contains both coal and quartz dust as well as other mineral constituents. For samples collected at coal mines, the U.S. Mine Safety and Health Administration (MSHA) utilizes the P7 method for respirable quartz analysis. The objectives of this work are to 1) evaluate the performance of the P7 method on field samples of low quartz mass loadings, 2) evaluate the magnitude of dust mass spatial variability within an enclosed cab environment, and 3) estimate the subsequent propagation of error in calculating the percentage of quartz over a broad range of mass and quartz filter loadings at a...

Influence of Coal Type on Water Spray Suppression of Airborne Respirable Dust

A laboratory study was conducted to investigate the water spray capture efficiency of airborne respirable dust generated from nine different bituminous coal seams. Experiments involved grinding a uniform coal sample mass, injecting the dust into a closed steady-state chamber, and measuring the aerosols decay response when exposed to a hollow cone water spray. The amount of airborne dust generated from these differential coal types varied, but had similar particle size distributions. The spray knockdown efficiency was comparable among coal types, and the size distribution of the dust was uniformly reduced by the water spray. Since water spray capture efficiency remained essentially uniform, the dust concentration at the end of the spray period was a function of the amount of dust generated. Therefore, a particular water spray system used in different coal seams under identical operating conditions (seam height, airflow, water pressure and flow, mining practices, etc.) can be expected to remove airborne du...

The Cost of Respirable Coal Mine Dust: An Analysis Based on New Black Lung Claims

Abstract The objectives of this article are (1) to provide for the first time a summation of the monetary costs of new compensation claims associated with levels of unmitigated respirable coal mine dust and the resultant lung disease known as black lung and (2) to compare these compensation costs to the cost of dust control technology research by the Bureau of Mines. This article presents an analysis of these expenditures and projects these costs over the period from 1991 to 2010, based on projected future new claims which are assumed to be approved for federal and state benefit payment. Since current and future dust control research efforts cannot change past claim histories, a valid comparison of future research spending with other incurred costs must examine only the cost of future new claims. The bias of old claim costs was eliminated in this analysis by examining only claims since 1980. The results estimate that for an expected 339 new approved claims annually from 1991 to 2010, the Federal Trust Fun...

Design, testing, and modeling of environmental enclosures for controlling worker exposure to airborne contaminants

..........................................................................................................................