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GeneralJharia coal mine POTD

21st Apr 2018 11:44 UTCOlivier Mével Expert

Very impressive (and nice) photo from India uploaded from Wikimedia.

I however think a little questionable to "reward" photos from Wiki /pedia/media as POTD.

Let preserve the Mindat originality!

There are hundreds of nice photos on wikipedia and it's so easy to bring them back to Mindat.

Some photos are surely worth coming to Mindat if it can improve our database let empty of photos on special localities or other informations where mindat members fail to upload original photos.

To bring wikimedia photos to the POTD may not be encouraging for those who hike volcanoes, enter deep mines or travel in July to Kamchatka with Mindat adventures to catch some lovely personal original photos!

Olivier.

21st Apr 2018 14:55 UTCLarry Maltby Expert

In this case it seems that the photo and story is very worthwhile for the front page of Mindat. It really gets your attention. The fire has been burning since 1916 and it seems to me that digging allows more air to the fire causing even more problems. The full story can be found here.

https://en.wikipedia.org/wiki/Jharia_coalfield

21st Apr 2018 15:53 UTCDebbie Woolf Manager

Very interesting story, I would be non the wiser if it hadn't made POTD, I learnt from it!

Thanks Larry for the link.

22nd Apr 2018 16:52 UTCTom Tucker

Similar coal bed fires are common around the world. The Wyoming Geological Survey mentions 300 burning at any one time in Wyoming. In 2009 the Montana Department of Environmental Quality noted that they were planning to extinguish nine such fires that year. In Theodore Roosevelt National Park, in North Dakota, there is a hiking trail to the exposed smoking vent above a burning coal bed.

Such fires frequently result from spontaneous combustion, which can be enhanced by the presence of marcasite or pyrite. The fires may contribute to the origin of range and forest fires, or visa versa. Lightening has also been presented as an igniter of coal fires. The susceptibility of coal to spontaneously combust is an important factor in marketing coal. To be transported long distances by train, and then in ships to a foreign market, the coal must have a low capacity for spontaneous combustion.

The rocks above such burning coal beds are often baked, like brick, into "clinker", which can be up to ten times the thickness of the burning coal bed. There was a new mineral species described from clinker from Wyoming about 25 years ago - I don't remember the species. The beautiful salammoniac crystal clusters from Pennsylvania are a result of a burning coal fire.

22nd Apr 2018 19:45 UTCErik Vercammen Expert

I think the mineral you are looking for is esseneite https://www.mindat.org/min-1413.html

23rd Apr 2018 00:18 UTCNiels Brouwer

> Such fires frequently result from spontaneous

> combustion, which can be enhanced by the presence

> of marcasite or pyrite.

I wonder how the presence of pyrite or marcasite influences combustion of the coal. Is it because those often decompose easily? Is it because of the acids that are released in that process? Or something completely different? It would be interesting if you had some further info.

23rd Apr 2018 01:13 UTCAlfredo Petrov Manager

It's not the acid, it's the heat released by the iron sulphides as they oxidize (the infamous "pyrite disease"). In mineral collections the heat dissipates and is unnoticeable, but enclosed underground it can become significant. Pyrite-rich mines can burn even without coal being present, as at Jerome, Arizona.

23rd Apr 2018 01:14 UTCRichard Gibson 🌟

Niels, here's a link: https://link.springer.com/article/10.1007/s40789-015-0085-y

also the heating and chemical changes makes the pyrite-marcasite invert to pyrrhotite, at least enough to give the clinker/paralava a distinctive expression in aeromagnetic data.

23rd Apr 2018 01:38 UTCAlfredo Petrov Manager

I imagine the distinctive magnetic signature above clinker/paralava must also be due to the higher oxides of iron (like hematite) being reduced to magnetite, maghemite, wüstite, and even native iron.

23rd Apr 2018 01:52 UTCKeith Compton 🌟 Manager

The Burning Mountain locality at Wingen in New Soth Wales is believed to have started about 1,000 years ago and probably caused by the spontaneous combustion of coal due to the breakdown of pyrite.

23rd Apr 2018 03:02 UTCGregg Little 🌟

Base metal mines (Sullivan mine in British Columbia) with high grade sulphide ores also experience spontaneous combustion and underground mine fires.

To paraphrase some of the research, it is caused by oxidation of certain species of pyrrhotite where self-heating raises the ambient temperature to 100°C with exothermic formation of elemental sulphur in the presence of moisture and oxygen. The situation proceeds to a second stage in which the sulphur oxidizes to SO2 and if unchecked, ignition of the broken ore body could eventually occur.

29th Apr 2018 19:07 UTCGregg Little 🌟

I recently queried my older brother about mine fires in the Sudbury Basin; he was a senior engineering geologist with INCO from about 1968 to 2010. This is what he wrote.

" I will try to find out about mine fires. The two I know about were one at Levack where they had a misguided attempt to use pyrrhotite from a mill separation process as underground fill. As soon as air made its way to the site it would catch fire and we would diamond drill to pump water into the site. At Creighton the old square set stopes (full of timber, leftover high-grade ore, and unfilled openings) would spontaneously combust and there would be a flurry of activity to seal off the area."

Any further reports from Terry and I'll include them here or start a new thread. The Levack Mine was in the northwest corner of the Basin next to the Coleman Mine. Besides the usual copper and nickel ore they were also rich in PGE's. Interpretation on ore genesis is that the base and precious metals acted much like a density flow and settled down slope on the crater walls during cooling of the molten impact material.

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