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Author Pyrite eating bacteria/O2 levels in mines.
stuey

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 14:51:14
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I bumped into this caption on the interweb

"The main bacteria are thiobacillus ferrooxidans, thiobacillus thiooxidans and leptospirillum ferrooxidans plus a few more. Their favorite dinner is arsenopyrite, which they eat in enormous amounts producing iron oxide slime, suphuric acid (which we are walking in) and a few other by-products also heating the mine noticably. In the process they use up the oxygen from the air, especially leptospirillun ferrooxidans which isn't very enthusiastic about anaerobic lunches."

Which referred to the cause of Arseno/pyrite+oxygen--bacteria--> Sulphuric Acid and Ochre

This is very interesting as it explains several things. I've noted the warm draught coming out of the very acidic and very pyritous Wheal Jane, I've often wondered why air is bad and what the limits are in mines.

I always thought that pyrite was oxidised directly, via oxygen dragged in by fluctuating groundwater as well as dissolved oxygen.

So, since it appears these beasties are also at play, it leads me on to thinking about another pet worry of mine, bad air and the limits of such.

There are a few mines in the Scorrier area which have arseno/pyrite present as well as very poor ventilation. Chucking the meter down a few shafts, we've rarely seen anything below 14% but I gather it does get lower.

What I'm interested in is when these bacteria become dormant. At sufficiently low oxygen concs, I imagine these bacteria "hibernate".

I recall the story of a couple of chaps wandering into a stub in West Wheal Jane and dying due to the lack of oxygen. I wonder if this was due to the chemical oxidation of the air from freshly exposed oxidisables.

It makes me wonder if there is an absence of fresh ore, ironwork which can oxidise as well as no through draught, whether there is a lower limit to the level of oxygen which can be expected.

The observation of very low O2 levels indeed of a mine which was poked around in recently may suggest that biological oxidation can take it down to a degree (what? ) and then chemical oxidation can take it down a notch further......

The interweb has little at a first perusal, I wonder if any of you lot have any ideas.....? Thumb Up
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Morlock

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 16:49:13
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I would guess that there are areas of zero % O2?

Edit: The old iron nail in water under a bell jar experiment suggests all O2 is used in the reaction.
IP: 82.13.28.127 Edited: 02/01/2010 16:53:38 by Morlock
stuey

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 17:37:13
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http://wvmdtaskforce.com/proceedings/90/90HAM/90HAM.HTM

According to this paper, biological oxidation slows considerably below 8%

According to elsewhere, the chemical oxidation proceeds at a fair old rate until 1%.

I'm wondering whether the low oxygen we experience is due in the majority to this pathway, or whether there is some absorption of oxygen into the mine water for oxidisables in there.

It's pretty complicated!
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Morlock

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 18:05:57
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Yep, not at all simple. I'm fairly certain that in coal mines the O2 combines with just about everything present, coal, wood, belting, steel and oils/greases etc.
From your research it appears that after aerobic activity has ceased anaerobic takes over, the prevailing conditions at a particular mine must play a major part.

I am also wary of stirring up sediment in ill ventillated places.
IP: 82.14.67.116 Edited: 02/01/2010 18:09:46 by Morlock
carnkie

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 18:17:38
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Not that relevant to the thread but I remember this from a few weeks ago. I think the cause of the low O2 is still not known. [web link]

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derrickman

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 18:37:41
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coal mines may contain carbon monoxide, carbon dioxide, methane and a number of other anoxic gases released from the strata during and following excavation.

Wheal Jane was well known for anoxic conditions, Wolf ( I think? ) lamps were routinely used for that reason

the point about stirring up sediment is well made.
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stuey

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 19:24:02
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If I recall correctly, there are bacteria which munch pyrite and others which reduce sulphates (remove oxygen). Some of these create hydrogen sulphide. Not sure if they are an/aerobic or what.

I know that H2S can be explosive, but it's likely to kill you first!

The decomposition (chemical) of pyrite liberates a lot of heat and that speeds the reaction up a fair bit. I imagine fresh drives through pyritous material could make ventilation pretty critical.

I can't remember the chaps name, but I'm sure one of the chaps on here is a leading researcher in this field.....

Anyway....
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derrickman

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 19:31:10
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the real tragedy of the two fatalities at Wheal Jane was that the two in question were specimen hunting in an area screened by ventilation bratticing.The problem was well known and procedures were in place. One of them was due to be married within the next few weeks. IP: 92.3.129.52
BertyBasset

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Pyrite eating bacteria/O2 levels in mines.
Posted: 02/01/2010 23:04:09
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The only place where I had qualms about bad air was in the Glyn Llugwy mine next to the A5 at Capel Curig. There was a bit of a whiff, and noxious bubbles could clearly be seen coming up when walking down one of the levels. A quick exit was executed.

Robin
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carnkie

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 00:22:39
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On the other hand:[web link]

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stuey

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 12:44:33
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There are bubbles coming out of the water at Blow Shaft (Wheal Speedwell) which I suspect are H2S. I also gather a dog died there which was unlikely to have been due to the drop.....

I did some work on Copper (I) compounds with S containing ligands. One of the byproducts was loads of H2S. People would curse the smell when they came into the lab, but I was totally immune!

I have no idea what the concentration was, but it was well over the smell threshold and well below the toxic dose.

One of the by products of something similar was a mushroom smell which had the same affect on the sense of smell. It was truly vile.

The LEL of H2S is about 4.5% ish

Interesting link here. Note the bit about the egg smell turning to sickly sweet smell at about 30ppm.

[web link]
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Graigfawr

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 14:44:17
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Thiobacillus ferrooxidans and Leptospirillum ferrooxidans (mentioned at the start of htis thread), along with Ferromicrobium acidophilus and Acidophilium ferrireducens occur on a notable scale at Cae Coch 'sulphur' mine [actually fine-grained pyrite], in north Wales.

The pyrite oxidises and produces sulphuric acid (pH down to 2.0). This environment supports bacteria that fix CO2 like plants but in the absence of light, some using energy from the oxidation of the iron in the pyrite; others from the oxidation of sulphide and reduced sulphide compounds; and still others using energy from both sources.

Thiobacillus ferrooxidans and Leptospirillum ferrooxidans are abundant, occurring as gealtinous creamy deposits in flowing mine water, on wet rock, and as stalactites. They are akin to bogies with lengths up to several metres. These deposits support specialised protozoa and rotifera.

A number of scietific papers on the bacteria and lower life forms that occur in the mine have been published (maonly by researchers at Bangor University) and popular accounts have appeared in Descent, and a brief summary occurs in J.Bennet & R.W.Vernon 'Mines of the Gwydyr Forest: part 7: Llanrwst: Coed Gwydyr and Cae Coch, Llangelynin: Trecastell and Derwen Deg', Warrington, 1997.

I have experienced disorientation, shortness of breath and splitting headaches during and after trips to the mine. I have always carefully avoided the acid pools: the PH levels observed would cause long-lasting injury. These are environments to treat with great caution.
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carnkie

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 15:28:35
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The Iron Mountain copper mine in northern California may be of interest. The mine is the source of extremely acidic mine drainage which also contains large amounts of zinc, copper and cadmium. One of America's most toxic waste sites, it has been listed as a Federal Superfund site since 1983.

From a case study of the mine.

In 2000, microbiologists conducting research inside Iron Mountain announced the discovery of a new species of iron-oxidizing Archaea (along with plants and animals, one of the three primary forms of life on Earth) that thrives in the extreme conditions found in the mine. This organism (christened Ferroplasma acidarmanus) grows on the surface of exposed pyrite ore in pools of water so acidic that they were previously thought to be inhospitable to all forms of life. It greatly accelerates the rate of oxidative dissolution of pyrite, the process that produces acid mine drainage by converting iron sulfide minerals to sulfuric acid. The discovery of Ferroplasma acidarmanus helps explain why the acid mine drainage problem at Iron Mountain is so severe. According to EPA, the uncontrolled discharge of copper and zinc from IMM is equal to about one-fourth of the entire national discharge of these two metals to surface waters from industrial and municipal sources.

A link to the case study can be found here.[web link]

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stuey

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 15:37:40
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Interesting post, thanks!

Disorientation and Headaches are very much in the below 13% O2 area.

Pretty dodgy I would say. I recall a post somewhere about someone experiencing tunnel vision in a local mine around here. We tested it with a lighter and got a very odd flame/gap. A few weeks later, a couple of mates returned with a gas meter and beat a hasty retreat after it suddenly dipped below 10% a few feet further on.

One of the chaps is a med and explained that the physiological response is dependent on the saturation of your haemoglobin, which itself is pretty subjective due to smoking/age/fitness/size, etc.

I was aware that "snottites" were bacteria but I can't say I've really observed them in large amounts. Biofilms on water also seem to be pretty low in volume.... in a mine which is very acid due to these processes.

If snottites are composed of bacteria, it would suggest that the species they are metabolising are water soluble.....

Anyway, I think I have "enough" detail now! Big Grin
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Morlock

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 16:34:31
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Two close encounters with low O2, one in Harecastle Rail Tunnel whilst in a side heading to the derelict canal tunnel and the other under Dudley Zoo.
The zoo incident was possibly something given off by the copious amount of animal manure which had found its way down there. Big Grin
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derrickman

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 17:39:11
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canal tunnels can be very dodgy.

I worked on the Blisworth canal tunnel reconstruction in the 70s and ( quite apart from the appalling smell ) there was a huge amount of organic residue in the invert and a strict ventilation regime observed during excavation of this section
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Rossony

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 19:49:05
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Bacterial leaching, oxidation of sulphides and acid drainage have been documented from high-sulphide mines. It is quite noticable when examining mine workings in massive sulphide mines: increased heat compared to a low sulphide mine, occasional rotten egg (hydrogen sulphide) or just sulphide smell (depending on type of sulphides), and of course the environmentalists' favourist: acid drainage. These all consume various degrees of oxygen from the available air, but I think the process slows down with decreasing oxygen. The air may still support sufficient oxygen for breating, but the length of time underground should be reduced.

From my experience I have found that rotting timbers and rail ties left in old damp mines increase the possible bacterial leaching and oxidation. The smell may not be too pleasant, but I have never had a headache from it. The mine timbers will have a layer of "fur" on the surface, which I think is mainly from bacteria. The common cause of underground headaches is due to powder headaches from the explosives that have been used in poorly ventilated underground mines.

Acid drainage results from oxidation of sulphides exposed to a damp oxygen environment to produce sulphuric acid, which can get into the groundwater. Sulphide ore submerged under water will produce only minute amounts of sulphuric acid due to the low supply of oxygen.


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Morlock

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Pyrite eating bacteria/O2 levels in mines.
Posted: 03/01/2010 20:02:32
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derrickman wrote:

canal tunnels can be very dodgy.

I worked on the Blisworth canal tunnel reconstruction in the 70s and ( quite apart from the appalling smell ) there was a huge amount of organic residue in the invert and a strict ventilation regime observed during excavation of this section


I've had the pleasure of travelling through the repaired bit several times, thanks. Smile Lots of interesting small side headings, one with exhaust emission measuring kit.


(click image to open full size image in new window)

Edit: Some days you cannot see through it due to boat fumes. Big Grin
IP: 86.26.251.200 Edited: 03/01/2010 20:04:33 by Morlock
skippy

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Pyrite eating bacteria/O2 levels in mines.
Posted: 04/01/2010 18:32:39
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Again - slightly off topic - but when I was working in one of the gold mines near Southern Cross - Western Australia, we went through the oxidation boundary into primary sulphides. It was wet in the bottom of the pit. At the boundary, the ore was literally smoking. Yellow, sulphurous fumes filled the pit. Excavator tracks bubbled and fizzed away and dissolved within a week. Your boots fell to bits in a day. The ore stockpiles were yellow with sulphur - they dissolved and fizzed in front of your eyes (which were just about burned to bits after exposure to the acid fumes..) In short, a living version of Hades... Not something I'd recommend on a regular basis!



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stuey

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Pyrite eating bacteria/O2 levels in mines.
Posted: 04/01/2010 18:45:01
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I was contemplating this earlier. Hot lode in United produced some ridiculously high temperatures. I suspect beyond that of most normal microbes. There's another factor.....

I have a feeling that the sulphur you observed was mostly Ca Sulphate (aka gypsum) rather than elemental sulphur. (that's a quick hunch)

It had long been an aim of mine to collect a load of S from a volcanic vent and when I finally got around to it, despite the yellow tinge, most of it was calcium sulphate.

Continuing the theme of utterly mental conditions, I recall that Nangiles mine was so acid that the pumps had to be lined and it would "rot the boots off a man".

What is odd is that Hot Lode, which was clearly being oxidised to acid, among other things didn't require lined pumps.

IP: 87.114.48.185 Edited: 04/01/2010 18:46:23 by stuey
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