Mining Project: Engineering Design for Mine Fire Prevention and Atmospheric Monitoring Systems

Research Summary

This project had five research aims, as follows:

1. Obtain engineering data to develop guidelines for performance-based designs for installation of mine fire detection and suppression systems in conveyor belt entries and drive areas, stationary equipment, battery charging stations, and diesel fuel storage areas.
2. Validate improvements to the NIOSH-developed mine fire simulation program MFIRE.
3. Develop more effective engineering designs for installation of fire detection and suppression systems through the use of the new MFIRE 3.0 code combined with computational fluid dynamics (CFD) models such as the NIST FDS code.
4. Assess the overall fire hazard of combustible mine materials by studying and quantifying the properties that are most important to the processes of ignition, flaming, flame spread, and the production of toxic gases and smoke.
5. Evaluate the impact of both fire size and fires of different combustibles on underground ventilated mine atmospheres and utilize this information towards the development of improved and interactive atmospheric monitoring systems.

Fires have the potential to contaminate mine atmospheres with potentially lethal and debilitating levels of toxic gases and smoke. Although early warning fire detection is intended to prevent miner exposure to these hazards, knowledge of the actual levels of toxic gases such as CO, SO₂, H₂S, and NO_x produced, and the impact of fire size on the mine’s ventilation system, can be of significant benefit to understanding and reducing mine fire emergencies.

In this project, modern fire computer codes were augmented with numerical modeling to evaluate suppression system performance given the expanded conveyor belt drive area configurations currently in use. These numerical modeling codes and a NIOSH-developed ventilation/fire code were utilized to model the interactions of a mine fire with the suppression system and suppression agent. Flammability properties of in-mine materials were quantified to develop a database of key flammability characteristics, and to rank these materials according to a relative flammability index. Relative toxicities of these products will be measured, including variabilities in the properties of smoke that different combustion sources produce. A number of new-generation detectors for smoke and products of combustion were evaluated against the toxic byproducts generated to determine which of these detectors were most effective.

This work produced the guidelines and knowledge required for development of more effective engineered designs of fire detection and suppression systems, and developed a new methodology for assessment of total fire hazard of combustible materials.