Once dislodged from their parent source (coal or rock), the different dust particle sizes are released and suspended in the air posing danger to the health of workers and communities within the vicinity of coal mining operations. To effectively control airborne dust exposure in coal mines it is necessary to identify the sources of dust generation and quantify the amount of dust liberated by these sources. Dust exposure in coal mines results from longwall, continuous miners, and surface operations. But before we continue any further, we must answer the pertinent question – What is airborne dust exposure? – it is the short-term or long-term breathing in of respirable and inhalable fine dust particles which enter the pulmonary system, lodge in the depths of the lungs and result in diseases such as coal mine workers pneumoconiosis and silicosis. Inhalable airborne dust particles settle in the upper parts of the lungs whereas respirable dust particles are so fine that they are invisible and settle in the alveoli. Exposure to airborne dust is detrimental to coal miners’ health and is fatal. Quantification of airborne dust is one step away from dealing with the problem if airborne dust is not dealt with at its source.
It is important to highlight the relationship between knowledge of the danger of airborne dust as is related to efforts to deal with the dust at its source. Hence in this article, we focus on how to (1) reduce, (2) remove and (3) get rid of airborne dust in coal mines.
How to reduce airborne dust in coal mines?
Reduction of airborne dust in coal mines entails best-practice methods from the dust management plan that can lower the risk of exposure but do not eliminate its presence. These approaches are not at the apex of the hierarchy of controls but do play a pivotal role in dealing with airborne dust in coal mine operations. In as much as reduction plays a role, the longer a person is exposed to high concentrations of respirable dust, the more serious and life-altering the lung health disease becomes. To help reduce airborne dust levels in longwall operations, support activities can be limited during production shifts. Reduction of dust is achieved through limiting vehicle movement, removal of stoppings and delivering or unloading supplies during production shifts. The idea is to reduce air velocities that can cause dust to be entrained into the face ventilating airstream, especially if they occur close to the last open crosscut. In areas such as conveyor belt systems simple procedures such as belt maintenance, belt cleaning by scrapping and washing as well as the use of a rotary brush that cleans the conveying side of the belt can reduce airborne dust. Properly maintaining the belts is one of many vital operating practices necessary to keep respirable dust levels low along with the belt entry. Scraping and washing of the belt play an important role in reducing the amount of airborne dust generated by the conveyor belt. A motor-driven rotary brush that cleans the conveying side by rotating in the opposite direction of the conveyor belting helps reduce airborne dust levels along the belt.
How to remove airborne dust in coal mines?
One of the largest sources of operator dust exposure occurs from working downwind of the continuous miner. If the dry dust collector is not properly maintained and if the roof-bolter is not working downwind of the continuous miner, very little dust is exposed in the roof-bolter’s work environment. Efficient removal of airborne dust in coal mines takes places through maintenance of dust collecting systems. Hoses and gaskets should be checked for leaks and smoke tubes can be used to show where leaks occur. Primarily, use of dust collector bags is pivotal to removing airborne dust in coal mines. Dust collector bags can be used with dry dust collectors to minimise dust exposures when cleaning the dust box. Frequent cleaning of the main dust compartment is necessary to ensure proper operation of the dust collection system. The use of dust collector bags to contain dust in the main compartment allows workers to easily remove the dust from the main compartment and deposit it against the rib. Exposure during cleaning is reduced, the drill cuttings are located out of the entry traffic, and the canister filter can remain in operation for much longer because of the removal of the extra dust loading. Removal of airborne dust through cleaning of dust collector bags should be done in a well-ventilated area so that liberated dust is quickly removed from the operator’s breathing zone. Cyclone collectors are also designed to remove larger dust particles from the airstream before reaching the dust collector box. A sock can be attached on pre-cleaners to minimise the distance the dust falls unconfined.
How to get rid of airborne dust in coal mines?
Elimination of airborne dust at its source is at the apex of the hierarchy of control because it involves dealing with dust at its source. GRT specialises in different product ranges that control coal and silica dust. Chemistry and particle size are key to achieving elimination of airborne dust. Surfactant technologies have the potential to increase the wettability of dust by reducing the surface tension of the water and improving the capture of airborne dust particles. GRT Activate UG is a unique, ionically charged surfactant product that not only reduces surface tension rapidly, but changes the surface charge, capturing fugitive dust particles like a magnet, without affecting the calorific value of coal. Paired with the right sprays, like hydraulic nozzles produce fine-mist droplet sizes or air-assisted nozzles produce the smallest droplets of all sprays which match the particle sizes of fugitive airborne dust particles. Haul road trafficking dislodges dust particles from the surface and GRT Haul-Loc a specially formulated liquid polymer can be sprayed onto road surfaces to bind fine dust particles and prevent them from becoming airborne dust. If coal is wetted adequately at the face, less airborne dust will be created during transport at the transfer points. Increase in airflow at the belt entry, results in evaporation of moisture which is why water alone is not effective in coal dust suppression. Instead, a product like GRT Activate UG can be used to superactivate the water and eliminate the need to rewet the coal at multiple intervals along the conveyor belt system.
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Managing airborne dust in coal mines
Airborne dust exposure in coal mines occurs in many operations that generate dust. The journey from reducing, removing and getting rid of airborne dust requires a sound dust management plan. Are you reducing airborne coal dust? Are you removing airborne coal dust? Are you getting rid of airborne coal dust? Is water supply a growing concern? Are you looking for effective coal dust suppression additives to save water and make your water work? If you are struggling to deal with airborne dust in coal mines take time to reach out to GRT for your expert assessments and unique solutions that solve your dust control needs. It is a matter of saving lives if the dust management plan prioritises dealing with dust at its source.
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REFERENCES
Breathe Freely Australia. 2021. Silica and Coal Dust in Underground Coal Mining.
Breathe Freely Australia. 2021. Silica and Coal Dust in Open Cut Coal Mines.
