Introduction to Mine Gases | Indian Minerology

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Part 1: Introduction to Mine Gases

Key Learning Objective: Understand the types, sources, properties, and hazards of mine gases as per Coal Mines Regulations 2017 (CMR) and Metalliferous Mines Regulations 1961 (MMR).

1.1 Definition of Mine Gases

Mine gases are naturally occurring or generated gases found in underground or opencast mines that pose risks to workers, equipment, and operations. These gases can be flammable, toxic, or asphyxiating.

  • Firedamp: Mixture of methane and air (primarily CH₄)
  • Chokedamp: High CO₂ concentration causing suffocation
  • Blackdamp: Mixture of CO₂, N₂, and low O₂
  • Whitedamp: Carbon monoxide from explosions/blasts

1.2 Types of Mine Gases and Their Properties

Gas Chemical Formula Color/Odor LEL/UEL (%) TLV (ppm)
Methane CH₄ Colorless/Odorless 5-15% 1000
Carbon Monoxide CO Colorless/Odorless 12.5-74% 50
Carbon Dioxide CO₂ Colorless/Slight odor Non-flammable 5000
Hydrogen Sulphide H₂S Colorless/Rotten egg 4.3-46% 10
Nitrogen Dioxide NO₂ Reddish-brown Non-flammable 5

1.3 Sources of Gases in Mines

🪨 Geological Sources

  • Coal seams (Methane - 90-99% pure)
  • Strata pressure release
  • Coal oxidation (CO, CO₂)
  • Sulphide minerals (H₂S)

🔥 Man-made Sources

  • Blasting operations (NO₂, CO)
  • Diesel exhaust (CO, NOâ‚“)
  • Rock cutting/drilling
  • Electrical equipment heating

1.4 Hazards and Risks (CMR 2017 Compliance)

Hazard Type Gas Involved Statutory Limit Consequence
💥 Explosion Methane <1 airway="" in="" return="" td=""> Mine blast, fatalities
☠️ Asphyxiation CO₂ >3%, O₂ <19 .5="" td=""> Immediate evacuation Suffocation, unconsciousness
🩸 Toxic Poisoning CO >50ppm, H₂S >10ppm DGMS alarm levels Headache → Death

⚠️ Exam Important Points:

  • CMR 117: No person shall enter workings with >1.5% CH₄
  • CMR 120: CO >0.02% = danger signal
  • O₂ deficiency: <19 .5="" li="" unsafe="" zone="">
  • Methane drainage mandatory above 300m depth

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