Underground » Detection and Prevention of Fires and Explosions
In recent times, the effectiveness of traditional methods of coal dust explosion suppression in underground mines has come under increasing scrutiny. Current methods are based upon the widespread distribution of stone dust in mine roadways, and the construction of various types of explosion barriers utilizing stone dust or water. It has long been known that passive explosion barriers of this type are limited in the range of explosion conditions that can be successfully handled. Further, they are considered expensive, and difficult to install and maintain, particularly in a high production longwall panel.
Active explosion barriers differ significantly to traditional passive barriers by detecting the approach of an explosion and triggering the assisted dispersal of a suppression agent. Modern light detectors can be used to detect the approach of the explosion flame eliminating the reliance on pressure rise as a means of triggering, which has limited the application of active barrier technology to explosion suppression in the past. Trials of an active barrier system were recently successful in preventing the flame propagation in a coal dust explosion travelling at 120m/s.
This report presents the results of a project to demonstrate the capabilities of certain technologies for the development of a low cost effective active roadway explosion barrier that could be considered as an alternative to traditional passive barriers. The test work was carried out in conjunction with the South African company, Fire and Explosion Suppression Systems (FESS) at CSIR's Kloppersbos Explosion Testing Station. The barrier utilises components developed by FESS for military and civilian explosion and fire suppression.
Considerable difficulties were encountered early in the project due to technical problems but these were eventually overcome and the barrier worked effectively with minor modifications to the detection and dispersal system. Although only one successful test was achieved in this programme of work, it has demonstrated the feasibility of the concept and additional funding has been granted by ACARP to increase the scope of the demonstration project.
This report will present the results of the test conducted so far and the conclusions to be drawn from these tests.