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Introduction :
The firedamp is a particular source of danger to the safety in coal mines. At the slightest spark, it ignites and explodes, which can cause serious disasters such as that of Courrières of the 10th March 1906 which caused 1,099 dead and devastated more than 110 kilometers of galleries.
The firedamp's formation :
Firedamp consists of gaseous hydrocarbons, mainly methane (CH4), and small amounts of other gases such as carbon dioxide and nitrogen. It is an invisible, odorless gas, lighter than air and flammable.
It was formed during the coalification that is to say during the chemical-physical processing of vegetable raw materials in peat, lignite and coal, during geological times. It is a byproduct of the formation of coal.
Firedamp is partly adsorbed (trapped) and partly contained under pressure in the pores, the capillary spaces and cracks of coal and wall rock (wall defining a vein or layer).
The amount of gas trapped in the land varies from one place to another because it depends on the number of veins, the gas pressure, the structure and composition of the walls, the degree of coalification ... But in general, coal contains two to three times more natural gas than any other rock.
Anthracite is composed almost entirely of pure carbon, is not it possible that firedamp forms.
Reminder on "Earthcaches": There is no container or logbook on the given coordinates. Just visit the site and answer the questions by e-mail.There is no need to wait for my reply, feel free to log immediately after. If the answers are incorrect, I will let you know. Happy caching!
To validate your visit:
At the lamp room, you will find an explanatory board about firedamp:
1-. Where in the mine's gallery is the firedamp situated?
2-. What are the different levels we can be exposed to into a mine? What are, at each time, the consequences?
3-. Quote and explain at least one method used by the miners to detect the presence of firedamp.
During the galleries visit: :
4-. Which other(s) method(s) were used inside the mine to prevent the damages caused by the explosion of a gas pocket?
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