Underground » General
An ACARP supported study has been undertaken to evaluate a new realtime personal dust monitor for personal respirable dust evaluation use particularly in engineering studies. The evaluation is part of an international program of evaluation being undertaken by NIOSH in the US. It is believed to be the first personal dust monitor instrument (PDM) for use on mine faces that reliably delivers a near-real-time reading. It can quickly highlight high dust situations and allow the situation to be corrected.
The technology that forms the heart of the PDM, the TEOM® system is unique in its ability to collect suspended particles on a filter while simultaneously determining the accumulated mass. The monitor internally measures the true particle mass collected on its filter and results do not exhibit the same sensitivity to water spray as optically based measurement approaches. The technique achieves microgram level mass resolution even in the hostile mine environment, and reports dust loading data on a continuous basis. Using the device, miners and mine operators have the ability to view both the cumulative and projected end-of-shift mass concentration values, as well as a short-term 15 or 30 minute running average.
The project has contributed to general international assessment of the new instrument as part of a larger program being coordinated by Mr Jon Volkwein of NIOSH, Pittsburgh, USA. This study into use of the monitor as an engineering evaluation tool was also a pair to another Australian study being undertaken by Coal Services Pty Ltd evaluating the monitor as an alternative instrument for personal respirable dust sampling for meeting regulatory dust compliance standards.
The project was completed in four months. The US company contracted to manufacture the instrument, Rupprecht and Patashnick supported the project study in a number of ways including advice, training and the contributing of three instruments for the underground testing phase.
The instrument has been tested for robustness and potential to be used as an engineering tool to evaluate the effectiveness of dust control strategies. This project has evaluated the ability of the new PDM to quickly and accurately measure changes to longwall dust levels at manned points after implementation of an improvement. This was been done at two Australian longwall underground mines in a series of underground tests over 10 shifts. Results demonstrated the ability of the instrument to increase understanding of the respirable dust exposure levels faced at various underground manned points.
The project measurement program focused on recognised areas for improvement through examination of different engineering approaches such as spray configuration, man positioning, engineering design changes to the shearer and so on. The project aimed to contribute to assisting in developing an approach to sampling measurement that is reliable and repeatable and can ascertain efficiency or effectiveness of engineering improvements.
It was found that the best way to evaluate changing dust concentrations within mine sections was to download the monitors’ data of dust reading against time and then add recorded activity information, location and other information. Some of this latter information has to be recorded manually and some can be downloaded from the mine communication computer face or belt activity log.
The successful use of the instrument is a significant advance on the current shift length determinations taken by personal respirable monitors or the optical instruments.
The PDM has successfully demonstrated its potential use as an engineering tool to locate and assess various sources of dust during normal mining operations. The principles and concepts used to identify and remedy some of the higher dust levels are generally common sense and easy to understand.
Some technology transfer from the project took place through publications and conferences. Mine management from several mines have shown interests in obtaining the units when they meet IS standards in Australia and are commercially available.