|
Post by John on Jun 4, 2007 18:39:19 GMT -5
I can't grasp the concept of this method. Can anyone elaborate on how it's done??
|
|
|
Post by dazbt on Jun 6, 2007 7:05:11 GMT -5
I can't grasp the concept of this method. Can anyone elaborate on how it's done?? I think Horizon Mining is basically a method of extracting coal from inclined seams where roadways are driven into the same seam at different levels ............ but then again, I have heard the term used for Multi Pass Longwalls working in extremely thick seams, whereby coal is taken in separate layers. The latter method relies on either the roof or the floor of the second pass being on re-consolidated ground, consecutive strips being taken in steps going upwards on a false floor (back filled or stowed), whilst the opposite method ie. starting at the top of the seam and consecutive strips going down are made using the previous cuts consolidated goaf as a roof, not a method for the faint hearted. Another method for thick seam longwall machine extraction, I think originally called 'Suterage' (not sure of the spelling), is where the floor horizon is kept the same and the roof coal is allowed to break on the goaf line and is caught through closeable doors in the roof support canopy and removed on an AFC behind the chocks back legs, now although that sounds scary it seems a bit less terrifying than longwalling through a scour. Maybe that the multi-pass methods result in better control of surface subsidence damage.
|
|
|
Post by John on Jun 6, 2007 7:41:52 GMT -5
Hard to visualize Daz. That would be interesting.... NOT.. working thick seams via longwalling! Bad enough when the roof breaks up naturally without having a broken roof to start with!
|
|
limey
Shotfirer.
Posts: 75
|
Post by limey on Jun 6, 2007 12:35:03 GMT -5
My understanding is that it is a method for steeply inclined seams - similar to "stoping" used in hard rock mines, but using a sort-of inclined longwall technique. I believe that some German mines do it using a plough to remove the coal which is conveyed by gravity to the "lower" gate. How they prevent all the chocks from sliding down the face I do not know!
|
|
|
Post by dazbt on Jun 6, 2007 14:19:18 GMT -5
My understanding is that it is a method for steeply inclined seams - similar to "stoping" used in hard rock mines, but using a sort-of inclined longwall technique. I believe that some German mines do it using a plough to remove the coal which is conveyed by gravity to the "lower" gate. How they prevent all the chocks from sliding down the face I do not know! I believe that you are quite correct Limey, the coal is transfered by gravity down gate end chimneys but the faces are taken on the horizontal or close to that. Inclined Longwalls, i.e. inclined from main gate to tail gate have been worked in the UK, in collieries such as Seafield at a 0.9 degree inclination, with almost standard type roof support chocks. There was a terrible disaster at Seafield when a face collapsed as a result of alleged roof support inadequacies, www.users.zetnet.co.uk/mmartin/fifepits/starter/east/pits/s/pit-6.htm In many countries coal seams are extracted from vertical or near vertical seams, some methods, as you suggest apply to the metal mining principles of 'stoping', but also there are unique methods peculiar to each country, I was privileged to see a vertical coal seam in Spain being worked by what I could only call a 'lawn mower shearer' where the coal was cut from the the floor and pushed into a main gate chimney.
|
|
limey
Shotfirer.
Posts: 75
|
Post by limey on Jun 6, 2007 14:58:10 GMT -5
Yep! From my college days (!) I remember being taught that the ideal way to mine a sloping seam is "on strike" - that is the face is at a right angle to the dip of the seam - preferably with the coal being transported to the lower end to help the conveyor. The very steeply sloping seams that we are talking about have a dip angle of 45 degrees or more - I remember seeing pictures of a German face at 60 degrees!
I'm not sure if a "conventional" shearer could be used - it would be hell on the haulage system to get it to the "upper" end of the face! I also believe the lower gate road is driven entirely in rock below the seam and "chutes" are cut trough to the gate to extract the loose coal.
|
|
|
Post by dazbt on Jun 6, 2007 15:39:24 GMT -5
Yep! From my college days (!) I remember being taught that the ideal way to mine a sloping seam is "on strike" - that is the face is at a right angle to the dip of the seam - preferably with the coal being transported to the lower end to help the conveyor. The very steeply sloping seams that we are talking about have a dip angle of 45 degrees or more - I remember seeing pictures of a German face at 60 degrees! I'm not sure if a "conventional" shearer could be used - it would be hell on the haulage system to get it to the "upper" end of the face! I also believe the lower gate road is driven entirely in rock below the seam and "chutes" are cut trough to the gate to extract the loose coal. Well, I can relate from personal involvement that the coal seams at Seafield were taken by means of a standard AB 16 SERDS, fitted with an an hydraulicaly operated fail to safe parking brake (that wasn't quite adequate) but was supported and secured by an hydraulic rope winch arrangement. In slightly lesser angled sections the shearer was fitted with a drag type jack catch (a simple hinged bar that caught in the flight bars of the AFC and technically would prevent the shearer from running back faster than the AFC rate of travel), a good idea except that at 1 in 0.9 inclination the AFC pans were not fitted with chains or flight bars, relying entirely on gravitational flow of coal to the main gate.
|
|
limey
Shotfirer.
Posts: 75
|
Post by limey on Jun 7, 2007 6:25:26 GMT -5
Did you cut coal in both directions? I would have thought they would just cut coal going downhill, then flit back uphill. Sounds like a very hazardous situation could develop VERY quickly if everything did not go "just right" - and when does that happen in a coal mine?
|
|
|
Post by John on Jun 7, 2007 6:56:10 GMT -5
Did you cut coal in both directions? I would have thought they would just cut coal going downhill, then flit back uphill. Sounds like a very hazardous situation could develop VERY quickly if everything did not go "just right" - and when does that happen in a coal mine? Single Ended Ranging Drum, Limey. Them fitters like to get technical. ;D How on earth do they stop the chocks sliding off the face?? Supposing they used chocks?
|
|
limey
Shotfirer.
Posts: 75
|
Post by limey on Jun 7, 2007 8:17:46 GMT -5
How on earth do they stop the chocks sliding off the face?? Supposing they used chocks? Nailed 'em down?
|
|
|
Post by dazbt on Jun 7, 2007 8:21:43 GMT -5
|
|
|
Post by John on Jun 7, 2007 8:46:35 GMT -5
No, I looked at the site last night Daz, doesn't explain or show how they stopped the chocks sliding down the face. Huge crampons?? ;D
|
|
|
Post by dazbt on Jun 7, 2007 10:58:23 GMT -5
I meant that the problem chocks sliding down an inclined face wasn't always prevented, as the Seafield tragedy highllighted. I also remember an AM500 face in Romania being lost as a result of a similar slide down disaster sometime in the early 1980s If I recall correctly (and this memory is extremely hazy) the chocks on inclined faces were tied together with pivoting links, in groups or pairs. A great deal of care and coordination was required in advancing the AFC and chocks, i.e. sequencing of release and drawing in. When advancing a chock it would obviously always tend to creep or pull downhill into the lowside adjacent chock, some chocks I recall had a centering guide on the delta bar and in practice the released lowside chock could be pulled back up the incline by advancing the AFC with the upper adjacent chock. Chock Shields helped the situation by being in side abutment to each other. One seriously inclined face I worked on in Spain had gone through major problems with chocks and AFC sliding down the face to the extent that they had organised a system where an extra chock was kept at the tail gate and when the main gate chock eventually dropped off the face line it was removed and transfered back round to the tail gate on a cyclic system. Eventually they worked out that the AFC advance should always be done from the low side up and that the idiocy of releasing chocks randomly and in groups caused a heap of bother.
|
|
|
Post by John on Jun 7, 2007 12:17:59 GMT -5
I can now visualize what happens. Thats face in the link appeared to have Dowty Roodmasters by the description of the accident. I hated those chocks. if one wasn't set properly, ie advanced on to gummings and was our of vertical, they could topple over. I much preffered the Westfalias or Gullicks. More stable chocks.
|
|
|
Post by dazbt on Jun 7, 2007 14:15:35 GMT -5
In the process of having further time to think, a factor needed with us over 35 year olds, I do recall that on the early chock supported steeply inclined seam Longwalls there was a chock block left in each, that was used as a stell when pulling in against the lower chock, if that makes sense to older colliers.
|
|
|
Post by John on Oct 8, 2007 9:31:46 GMT -5
I was doing a little "Googling" the other day and found this piccie of a T/G in an inclined face mined by the horizon method. And this piccie of a test rig at Bretby, I wonder if they installed escalators on these faces.
|
|
|
Post by dazbt on Oct 8, 2007 14:24:44 GMT -5
I was doing a little "Googling" the other day and found this piccie of a T/G in an inclined face mined by the horizon method. And this piccie of a test rig at Bretby, I wonder if they installed escalators on these faces. At Seafield I recall a Longwall Shearer face inclined at 1 in 0.9, sometime mid 1970s and after the tragic disaster there.
|
|
|
Post by John on Oct 8, 2007 16:16:15 GMT -5
I think that T/G picture is a face at Seafield Daz.
|
|
|
Post by macfarlane on Sept 10, 2008 16:09:20 GMT -5
Hi boys from the book Horizontal mining by Fritzsche & Potts 1954 Horizontal mining was the driving of the main haulage roads on a slightly rising grade Neer horizontal to allow haulage by locos to take place at a constant grade. Down grade for fulls outbye and upgrade for empty inbye. the coal seams rising or falling due to faults of others were not followed by the main roadways
The second haulage at Lynemouth South followed the coal and ended up with the haulage rope with rollers on the roof as the way took the dip. The return rope had the Vee rollers fixed to the floor being held up by the rope tention. No horizontal work on this haulage section. Amacf
|
|
|
Post by John on Sept 10, 2008 16:38:35 GMT -5
Hi boys from the book Horizontal mining by Fritzsche & Potts 1954 Horizontal mining was the driving of the main haulage roads on a slightly rising grade Neer horizontal to allow haulage by locos to take place at a constant grade. Down grade for fulls outbye and upgrade for empty inbye. the coal seams rising or falling due to faults of others were not followed by the main roadways The second haulage at Lynemouth South followed the coal and ended up with the haulage rope with rollers on the roof as the way took the dip. The return rope had the Vee rollers fixed to the floor being held up by the rope tention. No horizontal work on this haulage section. Amacf Hi Mac, no horizon mining, it's where the seam is inclined as much as 1:1.5. So what they do is drive the main gate at the bottom and the tail gate at the top. Check the photos on this thread! How they stopped the chocks from sliding down the face, only those who worked them could comment. Places Horizon mining was practiced in the UK, were the Scottish coalfields, some in Wales and a few in Lancs. Also check Longwall and Shortwall mining board at the top of the index page.
|
|
|
Post by dazbt on Sept 10, 2008 16:57:12 GMT -5
"horizon mining, it's where the seam is inclined as much as 1:1.5."
and steeper, Seafield worked at least one modern longwall face at 1:0.9
|
|
|
Post by John on Sept 10, 2008 17:56:44 GMT -5
You'd earn your pay on a face like that Daz, a couple of times through it and you'd be all in!
|
|
|
Post by dazbt on Sept 11, 2008 3:10:06 GMT -5
You'd earn your pay on a face like that Daz, a couple of times through it and you'd be all in! I only went to Seafield a few times but I spent nearly 3 months working daily on a face in Spain which was at 1:1 for half its length then changed to 1:2. The Spanish face used a single ended AB 16MK2 haulage with a limited ranger gearhead the cutting drum was only 33" and incorporated a friction powered cowl, nominal extraction was around 36". The first day I arrived at the face I nearly died when I saw it, but believe it or not I found that actually getting through the face, both up and down wasn't half as bad as I envisaged, going up, after a bit of practise, was like using a ladder set at an easy incline, the problem was teaching yourself to climb without being able to bend your knees fully, coming down was a feet first slither. At Seafield there was a lot more floor to roof clearance which made travel easier, I seem to recall that the hardest part there was having to push through conveyor belting flaps hung at intervals in the chock track to prevent falling debris rolling downhill. Whilst I reckon it wasn't as bad as you might think I am more than gratefull that I don't have to face it these days, it takes me 10 minutes to climb up stairs to bed.
|
|
|
Post by John on Sept 11, 2008 6:33:38 GMT -5
And I used to moan about goaf flushings on low faces! By low I mean 36 inches. Yeh I know, there were lower faces! Bestwood had a 24 inch face, and there was some down to 18 inches in Durham.
|
|
|
Post by dazbt on Sept 11, 2008 7:59:02 GMT -5
And I used to moan about goaf flushings on low faces! By low I mean 36 inches. Yeh I know, there were lower faces! Bestwood had a 24 inch face, and there was some down to 18 inches in Durham. The chances were that the actual working space on a hand got prop and bar face at 18" wouldn't be a great deal less than on a chock supported face with 34" shearer extraction, when you reckon on a canopy being 3" or 4" thick, a chock base maybe 4" or 5", plus gummings that a chock might be sat on plus a bit of convergence so far back from the coalface. I can think of a few shearer faces that were literally a flat out crawl and some where you had take off your lamp battery and shove it in front of you. (or as mi grandad used to say, so thin that you could only take kippers for yer snap or jam sandwiches but you had to leave the jam off otherwise you couldn't get them through the face)
|
|
|
Post by John on Sept 11, 2008 9:18:41 GMT -5
Never had to take my battery off my belt Daz, but have gone belly flopping a few times where the goaf flushings made it impossible to crawl. 43's in the Piper seam got bad due to chronic convergence, to show how bad, the AB16/125 would complete a shear, start ploughing back and hit the roof beams! I've seen nearly a shift with the miners chopping the roof out over a lowered chock! The chocks were Westfalia's, so the canopy wasn't that thick, not like a roofmaster or a Gullick Seaman!
It was closing up so rapidly Management were thinking the face was a loss, that's where your old firm came in, the first double ended, conveyor mounted trepanner on field trials was diverted to Clifton. It got the nickname of "whirleygig". Being a thinner machine and being "bi-di" saved the day cutting 24 hours a day, managed to get through the poor geological conditions. It did so well the main gate rippers couldn't keep up with the advancement and the main gate ripping lip fell in, almost to the faceline. Wasn't long after that, that poor roof caught up with the face once more in the guise of the roof breaking up between the canopies and ahead of the face, pretty large cavities a couple of yards ahead of the face, finished the face for good. After that, the trepanner was transferred to a new face installed with Gullick Seaman five leg chocks. That face was the first face at Clifton under the new power loader agreement, if I recall correctly, everyone earned 25 quid a week flat rate pay, that was 1967.End of that year was the bad news, closure!
|
|
|
Post by Ragger on Sept 11, 2008 14:23:33 GMT -5
Never had to take my battery off my belt Daz, ! Never known an electrician who never took his battery off John, it must have been uncomfortable on top of those transformers and in a great coil of cable on nights. ;D ;D ;D
|
|
|
Post by John on Sept 11, 2008 14:29:05 GMT -5
Never had to take my battery off my belt Daz, ! Never known an electrician who never took his battery off John, it must have been uncomfortable on top of those transformers and in a great coil of cable on nights. ;D ;D ;D You like to kick a bloke when his knee pads are off Bill! Sleeping were out at Cotgrave, the Deps and Overmen would have sent you out the pit if they'd caught you there! Got plenty in at Clifton, but then again, I was an apprentice then, no responsibilities. Last few years I was in the industry, I was on swing shift, so didn't need sleep until I got home. Some of the tiredist blokes I worked with were Deputies!
|
|
|
Post by Ragger on Sept 11, 2008 14:41:10 GMT -5
Never known an electrician who never took his battery off John, it must have been uncomfortable on top of those transformers and in a great coil of cable on nights. ;D ;D ;D You like to kick a bloke when his knee pads are off Bill! Sleeping were out at Cotgrave, the Deps and Overmen would have sent you out the pit if they'd caught you there! Got plenty in at Clifton, but then again, I was an apprentice then, no responsibilities. Last few years I was in the industry, I was on swing shift, so didn't need sleep until I got home. Some of the tiredist blokes I worked with were Deputies! I can understand Deputies being tired John, all that delegating and report writing and thinking about the work others were doing, yawn, yawn, think I'll have a kip.
|
|
|
Post by John on Sept 12, 2008 6:46:26 GMT -5
As an old friend of mine stated, the Coal Board made us lazy! It's only when you left to work in private industry that you realize this. Although I didn't have to work with the team when I worked in Australia, boredom and the bonus pushes you. As the bonus was so good, we on the longwall split into two teams so as we didn't stop cutting at meal times. The fitter went with one lot and I the other lot with the Deputy "floating" because of his duties. That gave is two shearer drivers, one man on switch and two men pushing over and chocking on each small team. All major work was done before the first tea break. The system worked, continuous production and great bonus.
|
|