Underground » Health and Safety
A new Coal Dust Explosibility Meter (CDEM) for use in both statutory and engineering studies of Incombustible Content (IC) content of coal mine workings dust has been developed by NIOSH in the US. The objective of this project was to evaluate suitability of the CDEM monitor and also allow a group of mine dust samplers to be trained in its use the CDEM. The project was undertaken at the request of, and with the support of NIOSH as a means of evaluating the performance of the meter in on-site mine use. NIOSH has extended full cooperation during the study and their recommended approaches to procedures and analysis of data have been followed where appropriate to Australian conditions and sampling customs.
The meter has shown great promise. It is recommended that the unit's development plan be extended from the prototype stage to commercial development of a robust instrument for use on mine sites. It improves safety on mine sites by delivering a near-real time reading that can quickly highlight high dust situations and allow the situation to be corrected. The CDEM can be used by mine operators and safety officials themselves to manage day to day stone dusting operations by providing a more efficient balance between the applied limestone dust and mining generated coal dust. A recommendation is that it is in most cases easier to undertake the CDEM evaluation on the surface from the recently collected underground samples.
It is recommended that mine sites move to incorporate use of the CDEM in their stone dust management plan as the project concluded that the CDEM method is, in terms of accuracy, efficiency and timeliness at least as accurate, if not better a method, than laboratory oven ashing approaches for determination of the IC percentage for collected stone dust samples. This conclusion was reached from evaluations including various analysis steps undertaken at eight mines based on comparing results from CDEM sampling with two commonly used stone dust analysis methods namely the Colorimetric and the laboratory oven ashing method. It was reached after recognition that the CDEM:
· Accounts for coal dust size variation when determining the IC values;
· In not taking into account inherent ash in coal within the sampled matter, gives a conservative IC determination that provides an extra safety factor buffer; and
· Provided a high level of reliability and consistency when used in a re-examination of historical samples retained by a commercial stone dust laboratory.
It is recommended that mine site introduction of the CDEM include appropriate training to ensure accuracy and consistency of results between samplers. It is concluded that the CDEM demonstrates much promise for fast and accurate determinations of IC values in underground coal mines. Its introduction should include careful training for operators to ensure that accuracy is maintained through adoption of recommended instrument usage and sampling procedures.