Doctor of Philosophy
School of Civil, Mining and Environmental Engineering
Plush, Brian, Respirable and inhalable dust measurement and control efficiency determination in high production longwalls, Doctor of Philosophy thesis, School of Civil, Mining and Environmental Engineering, University of Wollongong, 2013. http://ro.uow.edu.au/theses/3878
Dust sampling in Australian coal mines is carried out with cyclone separation and collection of the sized particles for weighing, generally over the period of a full shift to measure personal exposure levels to airborne contaminants of employees. This testing methodology is described in AS2985 for determination of respirable dust and AS3640 for inhalable dust. These testing methodologies give an accurate figure for the personal dust exposure levels of employees for the period sampled, but cannot be related to any specific longwall operational sources of dust generation or to the efficiency of dust mitigation controls installed at those sources.
Fugitive dust on longwalls has always been an issue of concern for production, safety and the health of workers in the underground coal mining industry both in Australia and globally. Longwall personnel can be exposed to harmful respirable and inhalable dust from multiple dust generation sources including, but not limited to: intake entry, belt entry, stageloader/crusher, shearer, and chock advance. With the increase in production created from the advancement in longwall equipment, dust loads have also increased and this has resulted in an increase in exposure levels to personnel.
The main objective of this thesis was to develop a new dust monitoring methodology to quantify and document both respirable and inhalable dust magnitudes generated from different sources, and assess the efficiency of installed controls for the mitigation of produced dust, using gravimetric sampling as per statutory requirements. The resulting Dust Mitigation Efficiency (DME) model has been developed to identify respirable and inhalable dust loads at independent sources of dust generation on longwall faces and quantify the efficiency of installed controls for the mitigation of this produced dust.
The DME model will shed some fundamental and scientific insights into an area of genuine concern to the mining community and will enhance the current practices of statutory dust monitoring. It will also offer a significant benefit to the coal mining industry by providing a benchmark or signature dust load monitoring procedure along with the implementation of quantified best mitigation practices.
The DME model has been used to identify respirable and inhalable dust loads at independent sources of dust generation on longwall faces and quantify the efficiency of installed controls for the mitigation of this produced dust. The data collected from each of the sampled mines during the field trials has been used to create a benchmark or signature for each longwall of those mines in relation to dust loads from different sources of generation to ensure maximum efficiency in removing respirable and inhalable dusts.
The DME model has also successfully identified the most efficient installed engineering controls operating at individual sources of respirable and inhalable dust generation on operating longwalls in Australia. The use of the DME model as opposed to the statutory measurement process will allow mine operators to establish a dust mitigation regime based on the measured best practice for installed engineering controls.
A total of 360 samples were taken for data analysis to quantify the robustness of the DME model and determination of the best practice engineering controls. Of these, 190 were respirable samples and the remaining 170 were inhalable samples. With the DME model, it is envisaged that a greater reduction in both respirable and inhalable dust can be achieved with best practice engineering, which will have a direct reduction in exposure levels to workers on the face and significantly reduce the risk of lung disease in employees.
The establishment of the DME model for respirable and inhalable dust load identification and control efficiency determination has shown to be a valuable and robust informational tool that will have a significant benefit to not only the underground coal industry, but all industries that are affected by airborne contaminants less than 10 m in size (PM10). The ability to understand the actual dust production, coupled with the quantification of performance of installed engineering controls for dust mitigation, will give all operators of dust producing activities a valuable tool to better control their airborne contaminants.
It is suggested that further studies be undertaken to include;
- the use of Personal Dust Monitors (PDM’s) for data collection with the DME model used to calculate efficiencies;
- use of the DME model to better understand respirable and inhalable dust production and control in development panels and bord and pillar mining;
- medical research be conducted to understand how much respirable and inhalable dust is actually required to be ingested to create medical problems, and;
- comprehensive research into the accuracy of current exposure level limits and their suitability to the continually increasing production in the global mining industry.
By better understanding respirable and inhalable dust production and application of a best management practice to mitigate airborne contaminants, a significantly healthier workplace and environment will be achieved.