Robert A. Jankowski

Thoracic Dust Exposures on Longwall and Continuous Mining Sections

Abstract Past data on the prevalence of symptoms of chronic bronchitis and decreases in pulmonary function indicate a potential problem due to deposition of coal mine dust in the bronchial airways. Difficulty with dust control in certain jobs indicates that chronic bronchitis may continue to be a problem. Compliance with the respirable dust standard does not equally limit the thoracic dust exposure of all miners. Coal mine dust size distributions indicate that thoracic dust levels may be as high as five times respirable dust levels in some work areas on continuous mining sections and seven times respirable dust levels in some work areas on longwall mining sections. The largest thoracic dust generating sources are the longwall shearer, shield support advancement, and the continuous miner. The worst case scenario for thoracic dust exposure occurs on bidirectional cutting longwall mining sections where some mine personnel are very likely to work downwind of the shearer and/or support advancement for a signif...

Atomization of Water Sprays for Quartz Dust Control

Abstract The use of water spray systems for respirable dust control on continuous mining machines has been a traditional and relatively effective approach. However, with the implementation of more stringent dust standards due to quartz, the efficacy of these systems has been questioned. In response, the Bureau of Mines, U.S. Department of Interior, has undertaken a study to determine the relationship between spray pressure, total respirable dust control, and specific quartz dust control. Laboratory and full-scale model studies have been completed in an effort to evaluate the effectiveness of low-pressure, high-pressure, and combination water spray systems. Results of these tests indicate that high-pressure atomized sprays will improve reduction of all respirable dusts, especially dust in the 3.0-μm size range and below. These are also the size ranges that have been shown to contain the most significant amounts of airborne respirable quartz dust. Improved control techniques, such as those presented in this...

Correlations Between Measurements with RAM-land Gravimetric Samplers on Longwall Shearer Faces

Simultaneous RAM-1 and gravimetric personal sampler respirable dust measurements were made by the Bureau of Mines at two locations adjacent to a moving shearer on longwall faces. These locations were (1) 4.6 to 6.1 m (15 to 20 ft) on the ventilation intake side of the shearer headgate drum and (2) at the shearer midpoint, between the two operators. Despite the fact that the RAM-1 monitors were laboratory-calibrated to give equivalent readings, underground readings were often lower, particularly at the intake side of the shearer. The RAM-gravimetric ratio of all readings was 0.53 at the intake position and 0.75 at the midpoint position for all data. When only head-to-tail cut passes were analyzed, the RAM-gravimetric ratios were 0.53 at the intake position and 1.00 at the midpoint position. The difference between RAM arid gravimetric dust readings is attributed to a combination of factors such as ambient air velocity and cyclone orientation.

Substantial Time Savings Achieved Through Computer Dust Analysis

Abstract This article describes a computer analysis system used presently by the Bureau of Mines to analyze quickly and accurately large volumes of information obtained from real-time dust monitors during research studies. It substantially reduces the time necessary to perform various data analysis calculations and manipulations including graphics. It also provides raw data files that can be transferred to other software packages for other required manipulations. A major benefit of the computer analysis system is the availability of information at the end of each test day. Onsite analysis makes it possible to modify a study during the field evaluation process. The system does not alter the data collection process, other than requiring a small data logger instrument to be connected to each dust monitor. In some cases, the system has reduced manpower requirements during the data gathering phase. The system reduces the analysis time required by previous methods while improving many aspects of the data evalua...

Methane and dust controls for headgate cutouts

Abstract The headgate cutout is an area of concern for all retreating longwall mining operations. Because of the equipment and activities located in the headgate area, along with the ventilation flow pattern, methane and dust levels recorded at the shearer during the cutout are higher than for any other phase of the longwall mining cycle. This report presents several different techniques found by the Bureau of Mines over the past few years to successfully lower methane and dust levels during the headgate cutout for retreating longwall sections using antitropal ventilation (headgate to tailgate). Each of these techniques improves the health and safety of longwall workers and is economically feasible.