Mining method selection is determined by the depth and characteristics of the overlying strata and the quality and thickness of coal seams. Regardless of the method used for extraction, coal mining leads to several health associated problems which the article will also highlight in addition to the problematic areas specifically in underground coal mining and the solutions offered by Global Road Technology.  The most important problem arising from coal mining is respirable and inhalable coal dust exposure. It can lead to asthma, chronic obstructive pulmonary disease, stunted lung development, coal mine workers pneumoconiosis (CMWP), lung cancer, cardiac arrhythmias, acute myocardial infarction amongst many others. CMWP is considered to be the most common and serious disease, and the potential for exposure in underground mining is very high.

Size matters

The different stages of the coal mining process are accompanied by coal dust generation during coal cutting, transportation and preparation processes. The particle size distribution of coal dust is one of the most important factors which affects its reaction rate, solubility and human health hence precise characterization of coal dust size helps in prevention of CMWP. Secondly, geometry which refers to the shape and size of the particles influences the physical and chemical interactions at the coal face with studies showing that respirable particles with smaller size particles were more harmful to human health than larger particles. Deposition of coal dust particles on the lungs has been found to be size and shape-dependent as well. 

So other than size – why is it hazardous?

Chemically, they are 76 elements in coal with some elements such as arsenic, mercury and lead with are hazardous to human health. Research also shows that there are about 120 minerals in coal, for example, silica results in silicosis which over time can result in silicosis. Functional groups in coal affect the chemical properties and adsorption for toxic gases. Recent studies from about 3 years ago have shown that coal consists of aromatic structures, aliphatic chains, hydroxyl groups, carbonyl groups and silica functional groups. Chemistry continues to play a pivotal role in the applications of coal as studies have shown that free radicals exist in coal therefore strong reactivity of coal can also accelerate the effects on human health. The porosity of coal affects its adsorption properties hence increases the potential for adsorption of toxic gases, elements and minerals that may be dangerous to human health. The pathogenicity of coal dust as a result of inhalation of coal depends on the particle size. The detailed movement of either large or smaller particles in the body is heavily dependent on the biology of the mucosal and pulmonary systems. One of the modern and recent schools of thought has been working on defining coal dust from a nanoparticle perspective and although a few studies have been done on that subject it is important to note that coal dust nanoparticles have a large surface area which increases their adversity to human health more than larger particles. 

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Underground mining challenges

In Australia, fugitive dust on longwalls poses challenges to production, safety and health of coal mine workers in underground coal mining. The longwall workforce is exposed to harmful coal dust as the chemistry has depicted and unfortunately, it comes from different dust generation sources. Technology has not made it easier as advancement has brought an increase in production and ultimately rise in dust loads leading to increased exposure and in most cases overexposure to coal dust in underground coal mines. Analysis of the statistics of longwall coal mines in Australia as of 2011 shows that Australia had about 29 operating longwall coal mines. Of the 29, 18 were in NSW and 11 in QLD. Globally, Australia is the fourth largest coal producer and the largest coal exporter in the world. The multiple dust generation sources include but are not limited to intake entry, belt entry, stage loader or crusher, shearer and the shield advance. Getting in a bit more detail, studies indicate that the longwall shearer and chocks are the main dust sources on longwall faces with about 80% of the total dust make. Dust generated due to face spalling ahead of the shear is a major problem especially for thick seam longwall faces. Dust can also be generated at all the conveyor transfer points along the intake airways. 

Control – not just monitoring

The dust control measures implemented in underground mining depend on the nature of the dust source. Dust control in intake haul roadways has been performed using water but the drawbacks to using water include the need to consistently re-water as the air enhances the potential to dry out more quickly. Alternatively, people have resorted to hygroscopic and deliquescent salts to increase moisture retention capacity of the haul surface. Global Road Technology offers a cost-effective solution in GRT Activate UG which is used to super-activate water sprayed to control coal dust in longwall and continuous miner operations. It saturates the coal face and intercepts fine particles immobilizing fugitive coal dust without altering the calorific properties of coal but specifically targeting and ameliorating dust. Independent university testing showed that it is 12x more effective than water alone at capturing coal dust. The key areas for use of GRT Activate UG include safety management, efficiency, adaptability and environmental management. The protection of workers from the harmful effects of coal dust particles such as CMWP, improvement in the efficiency of existing spraying systems, applicability in coal dust conveyor systems and mitigatory measures to the surrounding environment and communities. 

Questions answered.

In order to provide a cost-effective dust control solution for underground mining, which is beneficial to the health and safety of the longwall miner, we had to answer three important questions. Firstly, why dust control is important in underground mining which we highlighted that the nature of coal more especially its chemistry can cause different health hazards to the coal mine workers. Secondly, which areas generate dust which we discovered a couple of areas generate dust including intake entry, belt entry, stage loader or crusher, shearer and the shield advance. Finally, which solutions are available and are cost-effective whilst offering safety management, efficiency, adaptability and environmental management multifaceted approach? GRT Activate UG was found to supersede other products available on the market. For your cost-effective dust control solutions in underground coal mining look no further as GRT offers the best return on investment in addition to expertise and workmanship that is a cut above the rest.

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Ren, T.X., Plush, B., and Aziz, N. 2011. Dust Controls and Monitoring Practices on Australian Longwalls. First International Symposium on Mine Safety Science and Engineering. 26. 1417-1429.