In addition to ventilation practices, the application of water via sprays is the most economical and popular means of combating respirable dust in an underground coal mine. Due to a noticeable increase in black lung among coal miners and new dust regulations, surfactants or wetting agents have been used to aid in dust suppression. The surfactant facilitates the wetting process by lowering the surface tension and allowing the hydrophobic coal dust to come into contact with the water.
One of the most straightforward and effective benchtop tests is a simple wetting test. Although there are variations of this type of test, principle and technique remain the same. A known amount of dust was placed on the surface of a solution and the time it takes for all the dust to fall through the interface would be the wetting rate. This investigation examined the specific density of the bulk dust and concentration of a surfactant in solution and their effects on the wetting rate. It was found that both factors were significant in determining the wetting rate. It was seen that the surfactant had a more significant effect on the dust which consisted mostly of coal particle when compared to a dust with a higher non-coal mineral content.
Additionally, full-scale tests were conducted to determine the effect of the surfactant at a constant concentration. During the field implementation, the surfactant was pumped through the mines spray water to the cutter heads of the continuous miner. A large number of uncontrollable variables present during the implementation, made determining the effects difficult, and the resulting impact from the surfactant inconclusive. Further long-term testing would be needed while accounting for all of the identified variables. Significantly higher concentration was however found when using the continuous personal dust monitor as opposed to the older personal dust samples when left in the same environment. Additionally, a very significant drop in dust concentrations was observed when the miner operators were allowed to activate the scrubbers. / Master of Science / People who work in mines are exposed to many dangers and illnesses. One of the illnesses, which has in recent history resurged, is black lung. Black lung is a disease caused by coal dust entering the lungs. The body’s reaction to it is to build scar tissue around the piece of dust. If this happens enough times over the miner’s career, then it becomes nearly impossible to breath. Normally, to prevent this from happening, water is sprayed in the coal before it is chipped off by the machine. Since this appears to no longer be effective, soapy chemicals are added to the water, which helps to keep the dust from lifting into the air in the first place.
One of the easiest ways to test whether the chemicals are working well or not is to conduct a wetting test. When conducting a wetting test, a known about of dust is placed on top of the water and chemical mixture, and the time it takes for all of the dust to be wet is call the wetting rate. To get better results in an actual mine, faster wetting rates were sought after. The wetting test showed that the two main factors which determine the wetting were how much coal is in the coal and rock dust mixture and how much chemical is used. It was seen that the chemical had a more significant effect on the dust which had mostly of coal particle when compared to dust with more rock dust.
Another study was conducted at a mine with only one mixture of water and chemical. During the study, the chemical was pumped through the mine and to the cutter heads of the continuous miner. A continuous miner is the name of the equipment used to mine coal and other soft material. The cutter head is the piece of the equipment which actually makes contact with coal. Since the conditions at the mine were not ideal and not enough data was taken, the resulting effect of the chemical could not be certain. More long-term studies need to be done in the future to help account for the less than ideal conditions. There were, however, larger amounts of dust when using new sampling equipment as opposed to the older equipment given the same conditions. Also, smaller amounts of dust were seen when the miner operators were allowed to activate the air cleaning attachments on the continuous miner. These issues should be revisited in the future.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/77951 |
| Date | 07 June 2017 |
| Creators | Brown, Connor Burton |
| Contributors | Mining and Minerals Engineering, Luxbacher, Kramer Davis, Sarver, Emily A., Luttrell, Gerald H. |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
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