Coal has been a valuable resource throughout history, but it was not until the early nineteenth century when it made a big impact in the world, as the industrial revolution started in Britain. Coal was burned to produce heat and electricity for use in industries. However, it was overtaken by petroleum as the world’s most used energy source in the mid twentieth century, before being propelled back to the top following the oil shocks of the 1970s. While the coal industry continues to play a vital role in modern economies, governments involved in mining, as well as relevant environmental bodies, also recognize the significance of reducing the effects of coal mining on the environment. Considering the potential for considerable dust emissions from coal mining activities, these bodies have identified the management of coal dust as a primary area for concern.
Why should coal dust be managed?
Coal dust refers to the fine powdered form of coal that is the results when coal is crushed, pulverized or ground during mechanical handling, mining or transportation. This dust is responsible for air pollution at both the local and regional level. The protection of air quality from coal related activities is aimed at reducing the amount of dust generated from blasting, wind erosion, and coal transportation. All mining operations are required by regulatory bodies to maintain a specific level of air quality, which is attained through proper management of dust emissions from the activities involved.
The dust also poses great risk to the health of communities living in close proximity to coal mines. The implication on community health depends on the nature of the dust particles, in terms of their size and origin, which is measured as PM or Particulate Matter. Finer particles of less than 2.5 microns in diameter pose a greater risk health, particularly for infants, children and elderly people with diabetes, heart disease or respiratory conditions, though coarse particles of PM 2.5 – 10 microns can also cause adverse health effects.
Dust particles of PM greater than 10 microns affect community amenities and reduce visibility. The impact is governed by a variety of factors including climatic conditions, particularly wind, and proximity to the mining site. These aspects affect dust deposits on house roofs or clothes, contamination of drinking water in storage tanks that are fed with dust filled waterways, and marine life by impacting fertility and growth of sea creatures.
Good Practices to Minimize the Environmental Impact of Coal Dust
Coal mining and other industries use a variety of monitoring and mitigation practices to reduce dust emissions from coal mining, transportation, and handling. Some dust mitigation measures include assessment of product moisture, use of enclosed loading and storage structures, and practical management practices like covering and wetting down exposed stockpiles. The following are good practices for mitigating dust emissions during different stages of coal mining:
Drilling and Blasting: the amount of dust generated from drilling and blasting operations depends on the type of soil and climatic conditions. The protection of air quality and community amenities in this phase is accomplished by employing pre-blast environmental checklists, examining real-time weather patterns, and using rigorous controls when blasting sensitive areas. All measurements are taken with consideration of the closest private residences, to ensure that they are unaffected by mining operations.
Material extraction: coal mining in open-cut mines involves the use of mobile excavation equipment like haulage trucks, drag lines, bull-dozers and front-end loaders to remove overburden and relocate it to emplacement areas. The activities involved in this phase including extraction, loading, conveying and dumping cause a lot of soil disturbance. While coal is often moist during mining, dust can still be produced when removing the coal seam, which tends to increase in dry and windy weather. Coal dust can be controlled during these operations by dumping overburden in low or in-pit emplacements, scheduling the operations for favorable weather conditions, and watering the work area to reduce dust generation.
Convey of Material: the extracted material can either be transported to the cost-handling and processing plant (CHPP) directly, or to run-of-mine stockpiles (ROM). Off-site transportation via rail often has minimal dust generation compared to transportation via haul trucks, especially if the haul roads are poorly designed, maintained, and managed. The material often has enough moisture to minimize dust generation, though dust emissions may increase depending on weather patterns and total time taken before complete enclosure in a train wagon or arrival at the CHPP. Dust control strategies to minimize pollution during transportation include: use of enclosed conveyor systems, use of automatic water sprays and small angle of inclination at ROM bin hopper, use of chemical dust suppressants, and proper maintenance of haul roads.
In conclusion, it is apparent that one of the critical factors for effective protection of the environment from coal dust is real-time weather data. Weather monitors for rainfall, wind speed and direction can help to reduce air pollution during various coal mining activities, in combination with a variety of other good practices like regular watering of the material, dumping overburden in stable enforcement areas, using wind blockers, using automatic sprayers for the stockpile area, and proper maintenance of haul roads. In addition, dust emissions caused by mining operations should be monitored on a regular basis in order to determine ambient dust levels and take the necessary corrective measures. One of the good examples of maintaining air quality regarding coal dust can be found with the Australian biggest port in Brisbane. The company has very strict measures which go a long way in coal dust mitigation and preservation of air quality.
