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MINE AIR
Greetings All! I am a new member to Mojave Underground, I want to begin by thanking all for the warm welcome I received.
After a couple of short email conversations with Stuart he asked that write a short article on Mine Air. How could I resist?
So, I have decided to do this writing in a few small articles. Each will be a little blurb on some of the aspects of mine ventilation and mine gases. It is nice to know what one might run into.
With some 20,000 mine opening in Utah to explore, it never hurts to have a bit of knowledge
Lets face it, our hobby is not one that is often viewed unkindly by some, (DOGM for instance) The better knowledge we have and can represent ourselves the more places we can access.
Entry areas, areas that are exposed to two or more openings, and areas that experience temperature variations are often naturally ventilated.
Aspiration occurs when the temperature of the mine in comparison to the changing ambient temperature outside can create a natural air movement.
Some areas however, such as a blind stopes, drifts etc. may no experience ventilation. In these areas buildup of various gasses can occur. I will cover some of this in a later article.
Let’s look at one interesting Mine Air occurrence; stratification.
Normally, air, once mixed will stay mixed. However, in a mine with very little ventilation, stratification can occur. This is where the air can become “layered†due to the mass of the molecules that are in normal air.
Lets look at a Drift that follows an up and down undulation while chasing an ore seam. Imagine a Sin Wave type of path
The air can separate (Stratify) much like oil and water separate. This is due to the mass of the different molecules that make up the air we breath.
As you can see below, the Mass of the different molecules can create a settling in various areas.
N2 = 14.0067 + 14.0067 =28.0134
O2 = 15.9994 + 15.9994 =31.9988
CO2 = 12.0107 + 15.9994 + 15.9994 =44.0095
So, you can have pockets of N2 in upper areas, O2 in the Middle, and CO2 in low areas.
Now this may not be a common occurrence, but it is one to be aware of and is just kind of interesting. The risk that this carries is experiencing asphyxiation symptoms due to displaced oxygen. Below are the symptoms.
20.9% Normal Air Percentage
19.5% Minimum Safe Entry Level
18-19% Poor coordination.
17% Fatigue
16.25% Mine Permissible Safety Lamp extinguishes.
16% Fatigue
12-16% Rapid Pulse, Labored Breathing
10-12% Very Fast, Deep Respiration, Lips Turn Blue, Headache
8-10% Fainting, Unconsciousness, Nausea, Vomiting
6-8% Your own “Light†goes out in 8 minutes.
So in our explorations, it is something to be mindful of although it of course is not meant to deter us.
An O2 Meter, A Canary (yes a canary, they still work just fine), or a Mine Safety Lamp can warn us of areas where oxygen has been displaced.
http://www.youtube.com/watch?v=hGipSCHXMbE (Thanks Stuart) This is an informative (if dated and dull) video on Mine Safety Lamps.
Next up…well, I am not sure, CO2, maybe CO, who knows.
Greetings All! I am a new member to Mojave Underground, I want to begin by thanking all for the warm welcome I received.
After a couple of short email conversations with Stuart he asked that write a short article on Mine Air. How could I resist?
So, I have decided to do this writing in a few small articles. Each will be a little blurb on some of the aspects of mine ventilation and mine gases. It is nice to know what one might run into.
With some 20,000 mine opening in Utah to explore, it never hurts to have a bit of knowledge
Lets face it, our hobby is not one that is often viewed unkindly by some, (DOGM for instance) The better knowledge we have and can represent ourselves the more places we can access.
Entry areas, areas that are exposed to two or more openings, and areas that experience temperature variations are often naturally ventilated.
Aspiration occurs when the temperature of the mine in comparison to the changing ambient temperature outside can create a natural air movement.
Some areas however, such as a blind stopes, drifts etc. may no experience ventilation. In these areas buildup of various gasses can occur. I will cover some of this in a later article.
Let’s look at one interesting Mine Air occurrence; stratification.
Normally, air, once mixed will stay mixed. However, in a mine with very little ventilation, stratification can occur. This is where the air can become “layered†due to the mass of the molecules that are in normal air.
Lets look at a Drift that follows an up and down undulation while chasing an ore seam. Imagine a Sin Wave type of path
The air can separate (Stratify) much like oil and water separate. This is due to the mass of the different molecules that make up the air we breath.
As you can see below, the Mass of the different molecules can create a settling in various areas.
N2 = 14.0067 + 14.0067 =28.0134
O2 = 15.9994 + 15.9994 =31.9988
CO2 = 12.0107 + 15.9994 + 15.9994 =44.0095
So, you can have pockets of N2 in upper areas, O2 in the Middle, and CO2 in low areas.
Now this may not be a common occurrence, but it is one to be aware of and is just kind of interesting. The risk that this carries is experiencing asphyxiation symptoms due to displaced oxygen. Below are the symptoms.
20.9% Normal Air Percentage
19.5% Minimum Safe Entry Level
18-19% Poor coordination.
17% Fatigue
16.25% Mine Permissible Safety Lamp extinguishes.
16% Fatigue
12-16% Rapid Pulse, Labored Breathing
10-12% Very Fast, Deep Respiration, Lips Turn Blue, Headache
8-10% Fainting, Unconsciousness, Nausea, Vomiting
6-8% Your own “Light†goes out in 8 minutes.
So in our explorations, it is something to be mindful of although it of course is not meant to deter us.
An O2 Meter, A Canary (yes a canary, they still work just fine), or a Mine Safety Lamp can warn us of areas where oxygen has been displaced.
http://www.youtube.com/watch?v=hGipSCHXMbE (Thanks Stuart) This is an informative (if dated and dull) video on Mine Safety Lamps.
Next up…well, I am not sure, CO2, maybe CO, who knows.
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