Mining is one of Australia’s most profitable businesses, however to what cost? The risks and dangers of working in an underground mine are quite well known. The processes and possible exposure to the miners, poses a mental, physical and psychological risk. If the appropriate health and safety measures are not implemented it can result in long lasting physical and psychological damage to the miners and their families. The Department of Justice has a document that specifically focuses on targeting all risks and implementing countermeasures to ensure the safety of the miners in the workspace. The primary risks for any miner are:

Gas Concentrations- ventilation officers are required to always be available onsite, with regular testing of areas where miners are working as well as any stockpiles that may be on site. As the miners excavate the ore, there is possibility of natural occurring gases to seep in, such as Methane, and accumulate in the underground mine site. The routine checks, and ongoing live monitoring, limits the probability of risks posed by accidentally tapping into unforeseen gas chambers.

Blasting- the explosive nature of this process causes suspension of a range of toxic fumes and gases, which can cause fatal lung tissue damage to any miners exposed. These gases include Carbon Dioxide, Oxides of Sulphur, Carbon Monoxide, Oxides of Nitrogen and other carcinogenic gases. Hence, why there are extensive and stringent guidelines to mitigate against any risks of exposure.

Integrity of the support structures within the mine- underground mining processes are destructive, which causes consistent vibrations, blasting and drilling. The rock that is constantly exposed to such processes may become weakened, and if not monitored consistently may easily jeopardise the integrity of the mine. Hence, why routine inspections of the infrastructure that is supporting the mine are undertaken frequently.

Dust: is the most toxic pollutants that affects Australia’s miner’s health. Dust is generated from a wide range of sources that are utilised within the industry. Multiple studies across the globe has recognised dust inhalation as one of the primary factors responsible for black lung. The threat, of course, is long term exposure when in a confined environment, such as those conditions found in underground mines.

Case Study: DUST

The property that makes dust so dangerous is its size. Dust particles are extremely small in size, making them easily disturbed and suspended. The dust particles are on average between 2.5um to 10um in size. The smaller the particle, the more dangerous as it’s able to be absorbed into the capillaries in the lungs. For context, 2.5um is 1/7th the size of a strand of human hair. The slightest of disturbances or vibrations can cause these dust particles to become suspended and become a serious health hazard. The main sources of dust suspension in an underground mine are:

Machinery
In an active underground mine, traffic is consistent with transport trucks, civil trucks, cars and other machinery constantly moving in and out of the mine. The larger the vehicle, the larger the disturbance. The large transport vehicles that are utilised to transport the mined ore out of the mine, even when empty, weigh approximately 80 tonnes, and when full can weigh over 300 tonnes. The rotation of the large tires can suspend a large amount of dust, this combined with vibrations of their diesel engines and heavy load can suspend a large quantity of dust extremely quickly. Even though there are ventilation systems in place, dust quantities can accumulate in extremely high concentrations, very quickly, especially in a confined space.
To further mitigate the risk, according to the Department of Justice there are protocols that assist in reducing risk that are deemed sufficient. This includes:

  • Providing adequate rescue equipment and breathing apparatuses on all persons in the mine at all times, and that miners that are trained in the use of this equipment are available or on call at the mine at all times while people are working.
  • Any idle stockpiles are covered to ensure no dust suspension.
  • It also must be ensured that if ventilation systems are switched off, or not working, no personnel are able to enter the underground mine.

Shearing
Shearing is one of the most common practices in the coal mining industry. It is utilised primarily during long wall mining and continuous mining operations. On the electric motor machine body there are horizontal cutting drums that are installed on the sides. Along these cutting drums there are cutting picks that rotate on a plane parallel to the surface of the wall. As this heavy-duty machinery makes contact with wall it tears the rock wall into smaller fragments of ore and rock. This violent movement and interaction with the wall triggers the release of various types of dust from all the materials that the machine comes into contact with, this does include coal dust, which is primarily responsible for black lung disease. Due to the large scale of this machine, the quantity of dust is capable of disturbing is significant. Any miners in the vicinity of the area may become exposed to the suspended dust, which poses a high threat to miner safety. Even if miners are fully equipped with the appropriate respiratory protection gear, the dust may still place the miners at risk. As shearing is one of the most common practices in coal mining processing, it is vital that the dust is reduced as much as possible. Water alternatives must be considered to ensure dust suspension is minimal.

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Blasting
The process of blasting is the breaking up of ore material via explosions. This process sends large quantities of soil and dust into the air. The mines are left to ventilate, and once the miners are permitted to enter the mine again, they heavily saturate the area with water. However, due to the amount of air constantly moving, the water quickly evaporates, again releasing the dust particles back into the air, and exposing miners to the toxic dust. As previously discussed in a previous article published by GRT, water as a method of controlling dust was identified as a fallacy. It never has been a reliable, nor sustainable method of controlling dust suspension effectively. It is only a quick, short-term fix, to a long term, and serious safety issue.

The risk, however, is not only isolated to health problems, but also safety to the workers and entire mine itself. Dust is composed of small particles of the material either being mined or the soil of which it is surrounded by. For example, in Queensland there are sulphide rich soils, which hold valuable ores, that are currently in the process of being mined. So, when working with sulphide minerals it must be taken into consideration that chemically, sulphide oxidises extremely quickly. If the small sulphide particles become disrupted and suspend in air, it creates a potentially deadly environment for all those within the mine. As when these particles are dispersed in air, sparks and heat flashing (from for example, blasting or from a car backfire) are capable of initiating an explosive reaction. In situations such as these, it can be a fatal hazard to have high concentrations of suspended dust particles in such a confined space with the miners, even if ventilation is sufficient. If water is utilised in this context, all it does is provide an excessive cost for an ineffective solution that can be managed in a much more efficient and cost effective manner.

In the next article dust suppression technology options will be discussed that can directly address the issues discussed in this article. Global Road Technologies specialises in such circumstances and environments where long term, cost effective and efficient methods of dust suppression are utilised to ensure the safety of our workers in the mining industry. Each dust suppression technology will be discussed to suit the needs of the client.

References:

https://www.legislation.wa.gov.au/legislation/prod/filestore.nsf/FileURL/mrdoc_29691.pdf/$FILE/Mines%20Safety%20and%20Inspection%20Regulations%201995%20-%20%5B06-d0-06%5D.pdf?OpenElement
https://coresafety.org/wp-content/uploads/2014/12/12-352MOD_12EE.pdf
http://undergroundcoal.com.au/fundamentals/07_equipment_3cut3.aspx