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Long Wall Application
Longwall face workers can be exposed to harmful respirable dust from multiple dust generation sources including:
Shearer
Shield support advance
Stageloader/crusher
Intake roadways
Face ventilation and water sprays are the two primary controls used for protecting workers from bing overexposed to harmful respirable dust particles in longwall mining.
Controlling Respirable Dust Levels:
The cutting action of the shearer is the primary source and the largest contributor to the respirable dust exposure of longwall face personnel. the breaking of coal/rock in the crusher generates large quantities of dust as well as which can mix with ventilating airstream and impacts the dust exposure of all personnel on the face.
MLS 100 DustCAP® concentrations:
2000: 1 Dilution
18 - 24 Bar Dispenser Unit: Needs to be resupplied each 8 hour shift
Water Pressure: 150 to 1000 psi for maximum results
Orifice Size: 1/4” to 5/16” to meter MLS 100
Note: Use 5/16 orifice if high silica rock is encountered.
To determine the correct MLS 100 DustCAP® content in water, take a sample of water from a spray unit. Allow the foam to settle. Shake bottle vigorously for a second or two. Check to see if the “DENSE” foam layer on the top of water is 1/2” to 3/4” high. There will be some large bubbles on the top of the foam layer. DO NOT COUNT the large bubbles.
A foam hight with the dispenser loaded with new bars should be 3/4” thick for the longwall unit and about 1/2” this for the miners unit, transfer points, crusher, etc. It is time to add some bars when the foam height is 3/8” from the sprays on the longwall unit and 1/4” on the miners unit.
MLS 100 DustCAP® Bars greatly improves water sprayer dust control effectiveness:
Crescent sprays may be placed on each ranging arm and typically focused inward toward the cutting drum. These sprayers are located on the top and end of the ranging arm which provides uniform wetting of the entire cutting zone.