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There are several hazardous gases that are the product of mining and mineral processing. These products, which include methane (CH4), carbon monoxide (CO), hydrogen sulphide (H2S), and hydrogen cyanide (H2CN), require continuous monitoring in order to protect the well-being of mining equipment and personnel.
Methane is the most common hazardous gas in mines - especially in coal mines, where large pockets may be present. Methane, which is lighter than air, tends to rise to the ceiling of a mine or tunnel leaving it virtually undetectable to the senses. Methane can cause injury or death by asphyxiation, when it is in high concentrations, or by exploding when ignited by a flame or spark.
Carbon monoxide (CO) is a product of combustion of organic matter under conditions of restricted oxygen supply, which prevents complete oxidation to carbon dioxide. Carbon monoxide is colorless, odorless, tasteless, and non-irritating, making it difficult for people to detect. Inhaling even relatively small amounts of it can lead to hypoxic injury, neurological damage, and possibly death. A concentration of as little as 0.04% (400 parts per million) carbon monoxide in the air can be fatal. It can be found in mines as a byproduct of vehicle exhaust and is also created by blasts and explosions (Afterdamp). Carbon monoxide is also present in smelting and blast furnace applications, where it is used as an agent in the reduction of metals, like iron, from their ores.
Hydrogen sulphide (H2S) is a highly poisonous gas common in most mines. Harmful concentrations are often found in gypsum mines, tunnel digging, caissons, and can be mixed with natural gas. Because it is heavier than air it tends to accumulate at the bottom of poorly ventilated spaces like mines. Although very pungent at first (rotten eggs/flatulence), it quickly deadens the sense of smell, so potential victims may be unaware of its presence until it is too late.
Cyanide extraction of gold may be used in areas where fine-gold bearing rocks are found. Sodium cyanide solution is mixed with finely-ground rock that is proven to contain gold and/or silver, and is then separated from the ground rock as gold cyanide and/or silver cyanide solution. Hydrogen cyanide may be a by-product of this process, resulting in unsafe concentrations in the place of work.
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| Hazard |
Source |
Safety Solution |
| Methane - Natural Gas (CH4) (combustible) |
Underground pockets |
Millennium II,
Millennium II BASIC,
MLP-SC1100 (Catalytic Bead),
MLP-SIR100 (Infrared) |
| Carbon Monoxide (CO) (toxic) |
Vehicle exhaust, Smoldering fires, Blast residue, Smelting Blast Furnaces, Explosions |
Millennium II,
Millennium II BASIC,
MLP-ST1600 (Electrochemical),
Gas Shield Junior or Senior |
| Hydrogen Sulphide (H2S) (toxic) |
Underground pockets |
Millennium II,
Millennium II BASIC,
MLP-ST1300 (Electrochemical),
Gas Shield Junior or Senior |
| Hydrogen Cyanide (HCN) (toxic) |
Gold processing |
Millennium II,
Millennium II BASIC,
Gas Shield Junior or Senior |
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