Dust control is the reduction or total elimination of dust at its source. Dust control in underground coal mines targets coal mining processes. Underground coal mining opens up one or more shafts into the earth. These shafts follow coal seams too deep for surface mining methods. There are two main methods for underground coal mining. Room-and-Pillar on seams that are flat or dipping. Longwall mining uses a mechanized coal shearer. It’s between a conveyor system and a series of self-advancing hydraulic roof supports. Longwall mining is the most common method used in Australia. The underground coal mining process first involves access to the seam from the surface. Once access is gained, workings are developed using roadways within the seam. The roadways are connected as cut-throughs forming coal pillars. The smallest pillar size is specified by legislation. The smallest dimension not less than 10% of seam depth. Pillar extraction is one of the many processes that generate dust. Thus dust control in underground mines is critical for worker safety and health. Recognised Standard 15 legislates dust control in underground coal mines in Australia. The article will discuss Recognised Standard 15. It will focus on dust control in underground coal mines in Australia. Global Road Technology’s best practice dust suppression will sum up the article. Emphasis will be on GRT’s latest Underground Coal Mining & Processing e-book now available on all digital platforms.
Recognised Standard 15 – the importance
Coal dust kills. It is matter of time. Coal dust control at the source saves lives. A coal dust management plan which targets coal chemistry is effective for elimination of coal dust. Recognised standard 15 takes safety and health of coal mine workers a notch up. It states ways to achieve an acceptable level of risk to persons working in coal mines. The gazette notice was set by the Minister for State Development and Minister for Natural Resources and Mines in 2017. Department of Natural Resources, Mines and Energy set out Recognised standard 15: Underground respirable dust control. It is under the Coal Mining Safety and Health Act 1999.
Recognised standard 15 relates to all activities at underground coal mines in Queensland. Any surface activities that generate surface dust in the mine intake airways of an underground coal mine are included. The site senior executive must develop a Dust Management Plan like other principal hazard management plans. Recognised standard 15 works with recognised standard 14: Monitoring respirable dust in coal mines and recognised standard 2: Control of risk management practices. The mine’s safety and health management system must consider all dust sources. Control measures must be implemented in the following areas of the underground coal mine:
- intake entry
- belt entry
- crusher
- shield advance
- outbye
- development panels
- extraction panels
- surface areas of underground mines that may affect the ventilation circuits entering the underground workings
Coal mining in Australia – facts and figures
Are environmental regulations, health and safety concerns or potential profit loss a concern right now?
Australia has coal reserves totaling almost 150 billion metric tons. Most of the coal mined in Australia is exported. Only one quarter is used in electricity across the country, although Australia also holds a dominant world position in metallurgical coal production and exports. China consumes most of the coal from Australia however recent tensions have cast uncertainty on trade relations. BHP and Glencore are the leading coal mining companies in Australia. Fugitive dust on longwalls has been a great concern for production, safety and health of workers in the underground coal mining industry in Australia. Coal mine workers exposure to harmful coal dust is from many sources. Advancement of longwall equipment has also increased dust load exposure to underground coal mine workers. Different dust control methods have been used for underground coal mines. The past four decades have seen these methods developed and implemented:
- ventilation controls
- water sprays mounted on shearer drums
- deep cutting
- modified cutting sequences
- shearer clearer
- dust extraction drum
- water infusion
- use of scrubbers at stage loader/belt transfer points
Are the advances in WHS keeping up with advances in mining?
Some of the methods above have worked – to a certain extent. Over time, coal seams have become thicker and production environments have changed. The need to meet production demands piles pressure on dust control. Extraction from thicker seams increases importance of dust control in underground coal mining. Effective dust control methods have become more crucial than ever. Coal mine workers health and safety is at stake. The workers tend to bear the brunt of economic gains from coal mining. In Australia, dust measurements in underground coal mines has specifications. AS2985 for respirable-size dust particles and AS3640 for inhalable size dust particles. These methods provide accurate measurement of total dust exposure for the period sampled. Unfortunately it only stops there. There is no direct measurement of the source, quantity and timing of coal dust entering the longwall. This makes it difficult to determine effectiveness of the different dust control technologies. It is for this reason that dust elimination at the source is a top priority in the hierarchy of underground coal dust control. Dust control in underground coal mines is non-negotiable. Elimination of dust at the source stops and prevents coal dust from entering the longwall from different sources. Achieving this enables safety and health of coal mine workers.
Industry best practice
Recognised Standard 15 mandates can be achieved using GRT products. Global Road Technology recently published a coal dust suppression e-book. Underground Coal Mining & Processing e-book presents a case study of underground coal mining. It shows dust control solutions offered by Global Road Technology. Water ineffectiveness, over-exposure to dust, lack of non-toxic solutions, water scarcity and complaints from communities were the problems. The first solution was GRT Activate, a biodegradable concentrated additive that lowers the surface tension of water. It is safe, non-toxic and has a low carbon footprint. GRT Activate sequestrates coal dust particles in the water droplet. This drops it out of suspension, and it falls to the ground. The second solution is the GRT Activate-UG. This concentrated additive is specific for the coal face. It super activates water which enables it to bind coal dust particles. Its use was for coal dust control in longwall coal mining operations, and it does not alter coal-burning properties. GRT Activate UG can also be applied to manage coal dust from conveyors, stockpiles or coal in transit. We welcome you to read our recently published e-book and joining the discussion.
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REFERENCES
Underground Coal Mining. Retrieved 20/02/2021
