Underground coal mines are the world's most dangerous workplace. Methane (firedamp) released from seams is explosive at 5-15 percent; coal dust triggers a secondary blast at a 40 g/m3 LEL. Soma 2014 (301 miners) was Turkey's worst industrial disaster. NFPA 122 covers metal/nonmetal and coal mines.
CH4 Firedamp and Coal Dust
- CH4 LEL: 5 percent vol
- UEL: 15 percent vol
- Auto-ignition: 537 C
- Coal dust LEL: 40 g/m3
- Kst: 125 bar.m/s (ST1)
NFPA 122 Ventilation
- Fresh air: 1.9 m3/s per worker
- CH4 alarm: 1 percent warning, 2 percent evacuate
- Return air: Main fan shaft length
- Auxiliary fan: Dead-end gallery
- Stone dust: Coal-dust inerting
Refuge Chamber
- Capacity: 20-40 persons
- O2 supply: 96 hours
- CO2 scrubber: LiOH canisters
- Air-lock: Outside/inside atmosphere
- Comms: Wired + wireless
Self-Rescuer
- SCSR: Self-Contained Self-Rescuer
- O2 candle: KO2 chemical
- Duration: 60 min in good conditions
- Every worker: Belt-worn
- Cache: Reserve every 100 m
Turkish and World Incidents
- Soma 2014: 301 dead - CO, fire
- Kozlu 1992: Firedamp - 263 dead
- Ermenek 2014: Flood - 18 dead
- Amasra 2022: TTK - 42 dead
- Upper Big Branch WV 2010: 29 dead
Mines with MEP Calc
MEP Calc sizes underground mine main fan capacity, CH4 alarm thresholds, refuge chamber O2 reserve and NFPA 122 ventilation.
Download MEP Calc on the App Store
Sources & Further Reading
NFPA 122, MSHA 30 CFR, Turkish Mining Law, ILO C176, EN 1710. NFPA 122 Metal/Nonmetal Mining.