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Post by Wheldale on May 24, 2013 13:06:33 GMT -5
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Post by dazbt on May 25, 2013 0:53:00 GMT -5
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Post by Wheldale on May 25, 2013 13:26:58 GMT -5
Alkane have a few of these sites. They set up the Wheldale, Bevercotes and Shirebrook sites. Makes you wonder what we did before North Sea gas came along!! lol
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Post by colly0410 on May 25, 2013 13:54:33 GMT -5
What % approximately of methane & other useful stuff is in coal mine gas? I expect it differs a bit from pit to pit....I presume they pump water out of the sump or some other low point of the mine to stop it flooding & blocking the gas suction pipe...
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Post by tygwyn on May 25, 2013 14:18:41 GMT -5
I take it the Pits mentioned above,are capped ,not filled?
Don`t know about the water in the Yorkshire and Midlands Pits,but they will have one hell of a job to sump any Welsh Mines.
I believe they bore into un-worked reserves,and extract from there,i would imagine.
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Post by Wheldale on May 25, 2013 14:34:28 GMT -5
The shafts vary, Wheldale is unfilled, so is Askern. Bevercotes are filled, a borehole was drilled into the pit bottom.
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Post by Wheldale on May 25, 2013 14:45:10 GMT -5
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Post by dazbt on May 25, 2013 14:46:09 GMT -5
Alkane have a few of these sites. They set up the Wheldale, Bevercotes and Shirebrook sites. Makes you wonder what we did before North Sea gas came along!! lol We cooked coal, simple really, smelly, mucky, inefficient but it worked fairly well. Hargreaves still cook coal just up the road from me, but the 200ft high flame above the coking plant would suggest they don't consider the evolved gasses worth the cost of capture. |
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Post by Wheldale on May 25, 2013 15:18:29 GMT -5
I was reading just now Daz that methane is allowed to be burnt or flared as the resulting CO2 causes alot less damage (ie greenhouse gasses) than just letting the methane escape.
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Post by John on May 25, 2013 15:42:17 GMT -5
There's all sorts of crap in coking oven gas Daz, it would need to go through retorts to collect tars and distillates, then through other cleaning processes to remove nitrogen, sulphur, CO and CO2.The old gasworks used to have all that gear, and they trucked away the tars etc to fractioning towers to get all the byproducts out of it..
There's a lot of the old north Notts pits that must be just venting methane, some had huge methane plants on the surface to collect and use the drained methane for gaseous seams.
I don't recall any gas problems at Clifton or Cotgrave, I don't think Hucknall or Linby had gas problems either.
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Post by tygwyn on May 25, 2013 16:53:33 GMT -5
I was reading just now Daz that methane is allowed to be burnt or flared as the resulting CO2 causes alot less damage (ie greenhouse gasses) than just letting the methane escape. Tata at Port Talbot,in their coking ovens,have a state of the art capture process,where gases are used to generate a fair bit of their electricity,cutting their bills. Surprising what products the old coking plants extracted from the coking coal, Where does the bulk of today`s Tar come from ,for tarmacadam? |
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Post by bulwellbrian on May 26, 2013 4:44:43 GMT -5
The steel works at Redcar, Sthingyhorpe and Port Talbot all have coke ovens and I am sure still recover all the by-products that they can including using the gas.
I remember that Harworth Colliery used to supply gas to a glass works next door. I think some pits used drained methane to heat the water for the baths.
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Post by dazbt on May 26, 2013 5:30:38 GMT -5
There's all sorts of crap in coking oven gas Daz, it would need to go through retorts to collect tars and distillates, then through other cleaning processes to remove nitrogen, sulphur, CO and CO2.The old gasworks used to have all that gear, and they trucked away the tars etc to fractioning towers to get all the byproducts out of it..
There's a lot of the old north Notts pits that must be just venting methane, some had huge methane plants on the surface to collect and use the drained methane for gaseous seams.
I don't recall any gas problems at Clifton or Cotgrave, I don't think Hucknall or Linby had gas problems either. Actually it's all part of keeping the Hargreaves Monkton Cokeworks in profit J, the 'crap' is not only extracted as part of the process but sold on in various 'purified' forms. Some of the gas that is extracted is used not only to provide heat to the ovens but I believe to generate electricity, but even that doesn't stop them burning off what must surely be millions of cubic metres of what could be useable gas. I seem to recall that many years ago there was a telescopic gas holder (we use to call them gasometers) a few hundred yards away from the ovens which might suggest that the gas was once held and distributed for domestic purposes, can't really see why the gas couldn't be used today rather than just flaring it off. |
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Post by John on May 26, 2013 6:59:08 GMT -5
Yep, Gasometers, used to be as common as pit headstocks years back.
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Post by dazbt on May 27, 2013 14:06:18 GMT -5
I've no technical knowledge as to exactly how they extract methane from disused collieries, but, I guess it must be some sort of advantage to drive an extractive bore hole into ground where the coal seams have already been opened, stressed and fractured thus allowing methane to evolve from the coal under its own influence. Old workings and coal blocks immediately adjacent that have been pre-stressed are surely providing 'pre-fracked' ground without them having to go to the trouble of fracturing virgin coal blocks as applied in the so called controversial 'fracking' methods. The other point about workings being flooded, I fail to see what major problem it would cause to collecting gas, one of the main concerns expressed by anti-fracking groups is that the water based chemical solutions used under pressure to extend the fracturing of the geology, is likely to cause a twofold problem of percolating through into the natural aquifers as well as a becoming a surface run off pollutant, so not only is the methane extracted by fracking, captured through water, it is actually collated by introducing pressurised water in the first place. I'm not sure, but it might well be that gas extraction is actually enhanced by means of the workings being flooded naturally, I might well be wrong but I can't see water being a major problem.
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Post by mineruk on May 27, 2013 14:56:00 GMT -5
There is a company in the North East called Five Quarter who have just had a grant of £15 million. Here is they web site it can explain it a lot better then I can write it. five-quarter.com/home.html hope this helps |
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Post by Wheldale on May 27, 2013 16:29:49 GMT -5
I've no technical knowledge as to exactly how they extract methane from disused collieries, but, I guess it must be some sort of advantage to drive an extractive bore hole into ground where the coal seams have already been opened, stressed and fractured thus allowing methane to evolve from the coal under its own influence. Old workings and coal blocks immediately adjacent that have been pre-stressed are surely providing 'pre-fracked' ground without them having to go to the trouble of fracturing virgin coal blocks as applied in the so called controversial 'fracking' methods. The other point about workings being flooded, I fail to see what major problem it would cause to collecting gas, one of the main concerns expressed by anti-fracking groups is that the water based chemical solutions used under pressure to extend the fracturing of the geology, is likely to cause a twofold problem of percolating through into the natural aquifers as well as a becoming a surface run off pollutant, so not only is the methane extracted by fracking, captured through water, it is actually collated by introducing pressurised water in the first place. I'm not sure, but it might well be that gas extraction is actually enhanced by means of the workings being flooded naturally, I might well be wrong but I can't see water being a major problem. What I understand about extracting methane from old workings is that if the workings are flooded then changes in atmospheric pressure will not cause the gas to vent, therefor it does not vent from the mine. I don't know how the gas is collected from the shaft top. Point of Ayre colliery was flooded on closure to prevent gas from being vented from the shafts. It was flooded with sea water as it was next to the sea. I remember reading somewhere that a solution to prevent mine gas venting from old mines would be to flood them, this however was deemed too expensive at about 5 million quid per mine! |
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Post by John on May 27, 2013 17:22:57 GMT -5
Most old collieries will be flooded by now, there is a white paper on how they prevented flooding in the North Notts collieries and Cotgrave Colliery from water flowing from the old Derbyshire pits via old workings and then through the seams. All now would be totally flooded, the water authorities are a tad worried about contaminated mine water getting into the main water tables.
In Durham, the Coal Authority is pumping mine water from the eastern pits to prevent the water table being contaminated.
In Northumberland, mine water has already contaminated the water table...
Remember, seams outcrop to the west and dip around 4 to 5 degrees to the east....
I wonder of Selby is flooded yet..
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Post by tygwyn on May 27, 2013 17:28:27 GMT -5
I've no technical knowledge as to exactly how they extract methane from disused collieries, but, I guess it must be some sort of advantage to drive an extractive bore hole into ground where the coal seams have already been opened, stressed and fractured thus allowing methane to evolve from the coal under its own influence. Old workings and coal blocks immediately adjacent that have been pre-stressed are surely providing 'pre-fracked' ground without them having to go to the trouble of fracturing virgin coal blocks as applied in the so called controversial 'fracking' methods. The other point about workings being flooded, I fail to see what major problem it would cause to collecting gas, one of the main concerns expressed by anti-fracking groups is that the water based chemical solutions used under pressure to extend the fracturing of the geology, is likely to cause a twofold problem of percolating through into the natural aquifers as well as a becoming a surface run off pollutant, so not only is the methane extracted by fracking, captured through water, it is actually collated by introducing pressurised water in the first place. I'm not sure, but it might well be that gas extraction is actually enhanced by means of the workings being flooded naturally, I might well be wrong but I can't see water being a major problem. What I understand about extracting methane from old workings is that if the workings are flooded then changes in atmospheric pressure will not cause the gas to vent, therefor it does not vent from the mine. I don't know how the gas is collected from the shaft top. Point of Ayre colliery was flooded on closure to prevent gas from being vented from the shafts. It was flooded with sea water as it was next to the sea. I remember reading somewhere that a solution to prevent mine gas venting from old mines would be to flood them, this however was deemed too expensive at about 5 million quid per mine! I`m with Daz on this,gas will bubble up through water. In the late 70`s i worked in the Helig smallmine,near Cwmllynfell,working the Stwrin anthracite seam,down in the deep where i was working,gas was bubbling up through the bottom,seen in the water on the bottom side,we were driving slightly across pitch,this gas was coming up from the East Pit ,Peacock and Big Vein workings,totally flooded,as most Mines in South Wales would be,without pumping,which cost a lot of money,so find it strange they mention 5 million cost to flood a mine, Don`t it rain up North,butt,lol. |
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Post by Wheldale on May 28, 2013 1:54:47 GMT -5
From what I remember (it was a few years ago!) the 5 million quid to flood a mine was the cost of the water. Ie you would have pay for the water to be pumped from a nearby river. There were a few factors to this such as environmental stuff as I bet you could run a river dry by flooding a pit. It was one option of trying to control methane emissions from old mines.
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Post by dazbt on May 28, 2013 3:08:02 GMT -5
What I understand about extracting methane from old workings is that if the workings are flooded then changes in atmospheric pressure will not cause the gas to vent, therefor it does not vent from the mine. I don't know how the gas is collected from the shaft top. Point of Ayre colliery was flooded on closure to prevent gas from being vented from the shafts. It was flooded with sea water as it was next to the sea. I remember reading somewhere that a solution to prevent mine gas venting from old mines would be to flood them, this however was deemed too expensive at about 5 million quid per mine! I`m with Daz on this,gas will bubble up through water. In the late 70`s i worked in the Helig smallmine,near Cwmllynfell,working the Stwrin anthracite seam,down in the deep where i was working,gas was bubbling up through the bottom,seen in the water on the bottom side,we were driving slightly across pitch,this gas was coming up from the East Pit ,Peacock and Big Vein workings,totally flooded,as most Mines in South Wales would be,without pumping,which cost a lot of money,so find it strange they mention 5 million cost to flood a mine, Don`t it rain up North,butt,lol. Jim, that reminds me of working at Kiveton Park in the Two Foot in the 1980s, methane was a major problem, on several occasions very nearly disastrously so. But on the lighter side, the tail gate corner always had about 8” of water and was a nightmare to work in, methane constantly bubbled up from the floor and on bad days it was almost like ‘The Dancing Waters Display’ at Morecombe. The tail gate lads were constantly moaning about working in this amount of water and eventually got the manager to visit; he took one look and said “I can’t believe the amount of gas” the old guy chargehand said; “Them bubble aren’t gas boss, it’s our kid down there trying to set a foot pad” Ignitions There were five serious ignitions on the face side of the Buttock Shearer on this face, only three of which were ‘official’, the other two recorded as ‘showers of sparks’ one of these ‘showers of sparks’ was actually an explosion that blew the deputy manager into the gob between chocks, temporarily blinding him, burnt his hair and eyebrows off, the HMI became aware of this (a convoluted story as to how he got to know) stopped the face and initiated a major enquiry, the DM’s and other’s explanation of a spark shower resulted in the DM’s dismissal. I was on the face just behind the DM when this happened but level with the shearer which protected me from the main thrust of the blast. On another occasion I was present at the machine when there was a flash ignition which actually set fire not only to loose coal on top of the shearer gearhead but believe it or not the actual machine itself, anybody else ever seen a shearer on fire? |
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Post by Wheldale on May 28, 2013 4:57:28 GMT -5
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Post by dazbt on May 28, 2013 6:29:47 GMT -5
Well, that first report certainly defines the reduction in evolved methane from flooded mines. |
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Post by John on May 28, 2013 6:30:24 GMT -5
Wongawilli Colliery just south of Wollongong NSW was a wet pit working the Wongawilli seam, and methane was always bubbling out of the water from the lower seam, never caused us bother, and I never saw a cap on an oil lamp while working there. That's the only colliery I have seen high levels of methane at, the ventilation cleared it.
The year before I left the UK Appin Colliery had an explosion that killed several men caused by a methane, they were working The Wongawilli seam, gas probably from the seam below.....I read the reports from the court of inquiry...The aux vent fan was shown to me as it was under cover at Wongawilli where it had been brought for examination as it was the source of the ignition..
I don't think a cause was given, been many years now, but one thing stuck in my mind, the inside of the switch chamber was black from the ignition and the inside of the door was almost spotless!!! My thoughts were the electrician had a problem and was working with the door open and power on......... Australia doesn't like to make anyone a scapegoat in mining accidents.......
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Post by mineruk on May 28, 2013 10:48:18 GMT -5
I know Calverton is a water pumping shaft for the Notts Area also a methane drainage site.
Also Alkane have bought Maltby for £7 million.
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Post by dazbt on May 29, 2013 15:30:32 GMT -5
Well, that first report certainly defines the reduction in evolved methane from flooded mines. Well, I've been thinking (or at least trying to think) about this well proven system flooding of a mine in order to prevent the release of methane and I have to say that the more I think about it the more confused I become ............. I wish I'd paid more attention to school physics lessons, or then again perhaps not, I might have ended up as a book-logged AKAdemic rather than a spanner rattler. I'm having sleepless nights thinking about this, I can fully appreciate that the pressure of water being obviously a 'tad' greater than atmospheric could well form a resistance against a coal wall and restrict the natural release of methane into what otherwise would be a roadway cavity or goaf ........ but how flooding hinders the the quantity or rate of methane extraction by boreholes placed into destressed coal blocks defeats my tiny mind. I believe (but will confirm officially shortly) that most of the abandoned collieries within the Dearne Valley are now flooded to a great extent, but, it hasn't prevented at least two success full fairly large scale methane extraction plants in the area and a major problem of surface methane leakage into the midst of at least two housing estates. The 'puzzle' remains, at least as far as I'm concerned, if these so called AKAdemics believe that flooded coal mines aren't worth the trouble of methane exploitation then why are companies queuing up for bore-hole and extraction plant planning permissions? |
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Post by John on May 29, 2013 15:57:11 GMT -5
I'm in the same frame of mind as you Daz, I can't see water holding back too much methane.
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Post by Wheldale on May 29, 2013 17:03:56 GMT -5
Its my understanding (and I could be totally wrong!!) that the water when it fills the old mine workings is not affected by changes in atmospheric pressure as there is no ventilation in the mine. If you think back to basic mine ventilation, a drop in atmospheric air pressure allows methane to emit from a coal face, gob, fractured rock etc because the pressure of the gas is higher than the atmospheric air pressure. Like wise, a rise in air pressure reduces the amount of methane given off from the seams etc. When the workings fill with water (and maybe this could be due to the static head of water??), there is no air left in the workings so the air pressure cant drop which means methane cannot be emitted from the worked out area's. From the following link www.sciencedaily.com/releases/2010/04/100413122617.htm I copied the following paragraph, "Emissions occur when air is pumped into underground ground coal mines for ventilation, releasing methane into the atmosphere," In the case of methane drainage from old coal mines I assume (rightly or wrongly) that the workings must not be flooded and that there is some kind of ventilation so that methane can be emitted? I'm no expert on this subject, I could be totally wrong on this! |
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Post by tygwyn on May 30, 2013 2:41:13 GMT -5
This is all confusing,and i find when scientific papers come into it,it gets even more confusing.
So i personally like to look at things in a more practical and common sense approach.
If a Colliery is dry,then the methane extraction can carry on in much the same way as when the Colliery was working,as may be the case in the Maltby acquisition.
If the Colliery is closed,then several factors come into play,its location,the water table,number of seams worked,and connections to other Collieries in certain seams.
If no connections in the lower worked seams,then one can be fairly certain that them workings are flooded,but seams above that have been worked ,could be dry ,either through connections with other Collieries lower down the pitch of the seam ,or due to the water table in the area,to extraction can still be possible through the shaft.
Now we all know how wet the Collieries were in South Wales,its well documented how we trained Dolphins to bring the supplies in,lol.
But seriously,most of these Collieries will be well under water,but some of the older Collieries higher up the contour lines,have venting pipes in the caps,most likely the case of the water table or connections lower down the contour lines with other Collieries.
Now come to the case of a Colliery well flooded,all seams under water,boring down into any un-worked reserves would make sense,but what about boring down in the shaft pillar,would it be possible to extract methane,could enough air be pressured to extract methane through the flooded workings?
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Post by dazbt on May 30, 2013 4:04:45 GMT -5
Even if a colliery is dry I would think that after production or opening of new 'cavities' ceases, the overall amount of evolved methane must be reduced dramatically, but where methane feeders were producing from natural fractures then they would still produce, that surely is the whole point of the fracking process, to mechanically extend existing fractures and create new broken ground to allow the methane to exhaust into cavities created this way ............. so, the point that I can't get my head around is why in the case of adjacent workings being flooded why doesn't the imposed pressure of this water act upon the methane bearing strata allow if not encourage gasses to flow across the pressure drop into induced fractures, whether those fractures are created by intentional fracking or historic mining.
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