Z faces

[Wheldale]

Anyone ever worked or been on a Z face? I read that Thurcroft had one. Basically its a cross between an advancing and a retreating face. You have two parallel roads which are linked by one road. The face uses this linked road as a gate like in retreat mining. At the other end of the face the return gate is formed like it would be on an advancing face with a stable hole etc..

Theres a link here to a Z face at Thurcroft, the mine plan at the bottom shows the lay out of this one.

thurcroftcolliery.weebly.com/miscellaneous.html

[John]

Dec 16, 2013 13:54:43 GMT -5 Wheldale said:

Anyone ever worked or been on a Z face? I read that Thurcroft had one. Basically its a cross between an advancing and a retreating face. You have two parallel roads which are linked by one road. The face uses this linked road as a gate like in retreat mining. At the other end of the face the return gate is formed like it would be on an advancing face with a stable hole etc..

Theres a link here to a Z face at Thurcroft, the mine plan at the bottom shows the lay out of this one.

thurcroftcolliery.weebly.com/miscellaneous.html

I've heard of an advancing face, with a retreat set up in the adjacent panel, once the advancing face reached the boundary, the equipment was transferred across to the new faceline, then retreated, leaving a set of chain pillars to form a barrier between the two faces..
Is this what you mean??

Not sure how safe it is, but doesn't seem to have been universally accepted practice..

[Wheldale]

Ive read about them before John, just never seen one before. Then I was looking at the Thurcroft main website and noticed they had one. Just wondered if any one had worked on one before? They have a main gate that is allowed to collapse behind the face as it advances/retreats and a tail gate that has to be maintained as the face advances/retreats.

Steve

[Wheldale]

This is the layout I meant (if you can make any sence to it? LOL)

To parallel roads are connected by a single 90 degree road. This road acts as one side of the face gate which is allowed to collapse behind it, the second road on the right hand side of the face is developed as the face advances. Clear as mud! lol

[John]

Dec 16, 2013 15:46:48 GMT -5 Wheldale said:

View Attachment


This is the layout I meant (if you can make any sence to it? LOL)

To parallel roads are connected by a single 90 degree road. This road acts as one side of the face gate which is allowed to collapse behind it, the second road on the right hand side of the face is developed as the face advances. Clear as mud! lol

Been a while since I came across advanced longwalling, then retreat after the boundary was reached... But slightly different to the example you show Steve.
In the one I read about, I think it was in NSW, they developed two roads to the boundary, much like we did at Angus Place, one will be the M/G of the face being driven, the other will be the retreat T/G..That way there will always be a barrier to protect the gate road, then another pair of roads driven the panel width inbye, then two more the panel width for future faces.
I think most private mining companies prefer full retreat though, that way you have a rough idea what to expect when you start retreating, as against find problems that can stop a face part way through the panel.
Bit harder in thin seams, as the development of roads are partly in dirt, so not much profit in development roads.
The seams I worked in down under were pretty thick, so development was totally in coal, as long as development kept to plan, a road paid for itself in coal output.

[colly0410]

When at Moorgreen TC (1968) we went on a face visit to 66's in the Waterloo seam, they called it a semi-retreating face, sounds a bit like these Z faces. We went up the advancing tail gate then turned left onto the face, when we got to the stage loader the coal went left on a belt & we turned right after climbing over the (standing) belt, after walking a few hundred yards up the roadway we turned left & onto another roadway & went to look at some headings. I'm presuming the the main gate was a pre-existing roadway that was re-used as a gate road..

[drgjs]

Hey you guys are speaking a strange mining language.
I think it might be because I've only ever encountered surface coal mining on more massive scales (Australia, South Africa - got some really cool vids and pics if anyone interested) but I ain't got a clue what your saying (even with the diagram). Inbye? TG?
However, I'm looking at a case with a pillar between two mines, might be something along same lines from what I can gather. Are you saying you are blasting along different free faces?

[John]

Dec 16, 2013 17:03:16 GMT -5 drgjs said:

Hey you guys are speaking a strange mining language.
I think it might be because I've only ever encountered surface coal mining on more massive scales (Australia, South Africa - got some really cool vids and pics if anyone interested) but I ain't got a clue what your saying (even with the diagram). Inbye? TG?
However, I'm looking at a case with a pillar between two mines, might be something along same lines from what I can gather. Are you saying you are blasting along different free faces?

Modern Collieries rarely use explosives these days, longwalls are completely mechanised with shearers in the hundreds of HP range now, roads are driven with continuous miners cutting the coal from the solid and loading the coal onto a shuttlecar.

There are some good videos in the video boards on this site, try here Site videos.

There is also a glossary of mining terms, not complete, but should help you out.

[colly0410]

In one of the plans of Thurcroft a road is called SO1's scour, never heard of that before & couldn't find it in mining glossary, could someone explain to thicko me please..

[gadge]

Dec 16, 2013 17:33:19 GMT -5 colly0410 said:

In one of the plans of Thurcroft a road is called SO1's scour, never heard of that before & couldn't find it in mining glossary, could someone explain to thicko me please..

Scouring is the practice of driving roadways through the consolidated wastes or "gob" hence a scour is a roadway formed thus .Also the term scouring could be applied to ripping and packing the gobside of a fully retreated faceline to form a return roadway serving the next panel along

[colly0410]

Thanks for the explanation Gadge..

[drgjs]

John, wow. Really?
Not sure this is the right place for this discussion now, but following on, the reason I joined this forum was because although I am involved deeply in mining of various kinds in the southern hemisphere [all involving blasting or rock breaking by explosive means] both surface and underground, I was having a conversation about how coal is blasted in this country today [so must be opencast somewhere still, might have been referring to Scotland] where they drill the overburden right through into the coal and aren't afraid to blow some of it up, unlike elsewhere where this would be seen as somewhat bad practice. This lead me to thinking that I have no idea about mining in my own country or its history, so here I am to learn.
But what a shocker. Shearers. Mechanical means. No blasting.
I will add a couple of vids to the discussion area you gave showing the type of coal mining I am involved with.

[John]

Dec 16, 2013 17:33:19 GMT -5 colly0410 said:

In one of the plans of Thurcroft a road is called SO1's scour, never heard of that before & couldn't find it in mining glossary, could someone explain to thicko me please..

Same here, new term to me, probably a local terminology....

[John]

Dec 17, 2013 3:07:54 GMT -5 drgjs said:

John, wow. Really?
Not sure this is the right place for this discussion now, but following on, the reason I joined this forum was because although I am involved deeply in mining of various kinds in the southern hemisphere [all involving blasting or rock breaking by explosive means] both surface and underground, I was having a conversation about how coal is blasted in this country today [so must be opencast somewhere still, might have been referring to Scotland] where they drill the overburden right through into the coal and aren't afraid to blow some of it up, unlike elsewhere where this would be seen as somewhat bad practice. This lead me to thinking that I have no idea about mining in my own country or its history, so here I am to learn.
But what a shocker. Shearers. Mechanical means. No blasting.
I will add a couple of vids to the discussion area you gave showing the type of coal mining I am involved with.

I spent nearly ten years between Wongawilli Colliery and Angus Place Colliery, and the only shot firing I recall was "a popper" to break a large lump of sandstone up in a gate of one of our longwalls. As the Manager was the only mine official with shotfiring experience, he was the one who charged and fired the round.

Now Renison Bell where I started in Australia, they used hundreds of tons of explosives in the stopes.

UK coal mines, explosives were used to fetch the ripping lip down on faces, plus fire the stable holes and dints out, and every development road was drilled and fired in the 60's, being taken over by road heading machines.

I doubt towards the end of the coal industry in the UK much explosives were used, as faces were using advanced headings driven by road headers.

I also did a few years with British Gypsum, who fired on the solid using a wedge pattern and delay dets, 80 pounds of triminite(sp) was the amount of explosives used in headings..rule of thumb was 80 pounds for 80 tons of gypsum.

CPL's Boulby potash mine used to undercut the heading and fire it, then muck it out with LHD's, all changed to cut and load it out with Continuous Miners now..Same as British Gypsum, cut and load with CM's..

[dazbt]

Dec 17, 2013 6:58:22 GMT -5 John said:

Dec 16, 2013 17:33:19 GMT -5 colly0410 said:

In one of the plans of Thurcroft a road is called SO1's scour, never heard of that before & couldn't find it in mining glossary, could someone explain to thicko me please..

Same here, new term to me, probably a local terminology....

Scour is a well known term even used in Nottinghamshire coal mines, I'm surprised that a man of your vast mining knowledge has never heard the term J

[John]

Dec 17, 2013 9:42:16 GMT -5 dazbt said:

Dec 17, 2013 6:58:22 GMT -5 John said:

Same here, new term to me, probably a local terminology....

Scour is a well known term even used in Nottinghamshire coal mines, I'm surprised that a man of your vast mining knowledge has never heard the term J

No, never heard the term Daz and can't say I've come across it in any of the books I've read..

[drgjs]

John,
well I never!
In my world people say to me mechanical methods would be highly inefficient.
[Since that makes my silly opening posts, well, actually nonsense, I've modified them.]
I've add a link to a couple of videos of coal blasts down under and in south africa
in the videos board.
So why the difference? Why do we use mechanical methods here but explosives down there?

[John]

Dec 17, 2013 11:23:02 GMT -5 drgjs said:

John,
well I never!
In my world people say to me mechanical methods would be highly inefficient.
[Since that makes my silly opening posts, well, actually nonsense, I've modified them.]
I've add a link to a couple of videos of coal blasts down under and in south africa
in the videos board.
So why the difference? Why do we use mechanical methods here but explosives down there?

Probably efficiency, safety and costs.
Most Australian collieries using longwalls, produce in excess of 1.5 million tonnes per year with a face crew of around nine men, and that includes the electrician, fitter and Deputy. One Queensland colliery produces 5 million tonnes of coal from one longwall and a couple of developments.
Rate of roadway development using a CM is way more than one using the drill, fire and muck out method.
A hazard with explosives and coal is detonating methane and coal dust, so coal mining explosives used underground have to be of an approved kind, ie with added salts to reduce the chance of causing a dust ignition.

Many years back, pre mechanisation days, a longwall face was divided into "stints", each stint was cleaned out by a collier. The face was undercut, long and tedious hard work with a pick, then the face was pried down with "crowbars", then the lumps were loaded into tubs/wagons, the slack/fines ended up in the goaf, there was no market for fines.

Next came undercutters, the face was undercut, then drilled, charged with explosives, fired and hand loaded onto a rubber conveyor with shovel and hand..
Imagine around 20 men loading coal out by hand!! Then timbering the face, then another shift would dismantle the conveyor and re erect it closer to the face...

Then came machines, Meco-Moore, trepanners, and finally the Anderton Power Loader..Still slow hard work as the supports were either steel friction props with heavy roof bars, or wood props.
The final link to full automation came as powered self advancing supports, operated by hydraulics. Now a face could cut continually with little to hinder production.

24 hour production seven days a week, with a couple of maintenance shifts will probably yield 8 million tons of coal cut a year from one face.
I doubt very much you could achieve levels of production like that with minimum manpower with explosives in an underground coal mine.

Even gypsum, salt, potash and other mineral mines are now using Continuous Miners (CM's), replacing blasting methods previously used and achieving extremely high levels of production with minimum manpower.

There are some videos of coal faces in the video section of early longwall mining, plus a few of modern longwalls.

[Wheldale]

Dec 16, 2013 17:45:33 GMT -5 gadge said:

Dec 16, 2013 17:33:19 GMT -5 colly0410 said:

In one of the plans of Thurcroft a road is called SO1's scour, never heard of that before & couldn't find it in mining glossary, could someone explain to thicko me please..

Scouring is the practice of driving roadways through the consolidated wastes or "gob" hence a scour is a roadway formed thus .Also the term scouring could be applied to ripping and packing the gobside of a fully retreated faceline to form a return roadway serving the next panel along

I might be wrong on this one...... I think that a scour that is developed in the goaf stands better as it is in a "De-stressed zone". The road will stand better will less floor heave etc. But I could be wrong!

[colly0410]

[/quote]
Scouring is the practice of driving roadways through the consolidated wastes or "gob" hence a scour is a roadway formed thus .Also the term scouring could be applied to ripping and packing the gobside of a fully retreated faceline to form a return roadway serving the next panel along [/quote}]

Never heard of any roads being driven through old gobs down Hucknall. I presume it would be more difficult than going through virgin ground because the ground would be all broken up. Anyone got any experience of scours?..

[John]

The development for the drift down to the Ashgate seam at Clifton was done just above 51's goaf..51's was in the Tupton seam and was still cutting when the development was being driven, about half a mile outbye of 51's face between the main gate and tail gates...Conditions were perfect, probably as it was "de stressed" as Steve suggested....Ironic that so much had been spent on that development, as we were closed down before the drift itself was started..

Incidentally, that development was done firing on the solid and loading out with an old MC3 loader onto a scraper chain.

[tygwyn]

Dec 17, 2013 13:05:31 GMT -5 Wheldale said:

Dec 16, 2013 17:45:33 GMT -5 gadge said:

Scouring is the practice of driving roadways through the consolidated wastes or "gob" hence a scour is a roadway formed thus .Also the term scouring could be applied to ripping and packing the gobside of a fully retreated faceline to form a return roadway serving the next panel along

I might be wrong on this one...... I think that a scour that is developed in the goaf stands better as it is in a "De-stressed zone". The road will stand better will less floor heave etc. But I could be wrong!

Reckon your spot on there Wheldale,the area has already taken the squeeze,there is nothing else to come,bar for the immediate roof of the width of road,
Its just an expensive way to drive a roadway.

[drgjs]

John, of course I am only talking about my bit here, the removal of the rock on top of the coal so they can get at it. This "overburden" (usually weak sandstone like rocks) can be many meters deep. What they do to the coal itself comes after this, and food for thought indeed, I have never really gone into what happens then (i.e. after the rock blasting stage). Perhaps when I say I am involved in coal mining elsewhere, thats not quite right - I'm involved in mining rock for coal access. Its certainly good to learn new things. My big assumption was that there was still a large element of rock blasting to it in the UK. Likewise, never really thought how you got the coal out itself.

Yes I can well imagine the pre-mechanisation - I am also quite involved with projects in the "narrow reefs" of south africa - gold and platinum. The ore bearing rocks are thin "seams" or "reefs". These mines are underground, very narrow spaces, dangerous and difficult. The miners carry all their stuff to the faces, drill holes manually  (jack hammer drills) into the rock face in two rows along the reef, about 1 meter deep, 30mm ir so in diameter, typically less than half a meter apart. Perhaps 200 at a time. Load and leave the mine for 4-6 hours while the fumes and dust clear. They are luck to break 80% of what the drilled and loaded. The supports tend to get blasted out and need putting back. They can only blast once a day. Have some pics if interested.

[gadge]

Dec 17, 2013 13:19:19 GMT -5 colly0410 said:

Scouring is the practice of driving roadways through the consolidated wastes or "gob" hence a scour is a roadway formed thus .Also the term scouring could be applied to ripping and packing the gobside of a fully retreated faceline to form a return roadway serving the next panel along [/quote}]

Never heard of any roads being driven through old gobs down Hucknall. I presume it would be more difficult than going through virgin ground because the ground would be all broken up. Anyone got any experience of scours?..[/quote]I

Scouring was most probably not a common practice and newmillerdam was the only pit I worked at where I saw it done but as with all gobs the ground is broken up due to total caving and loses it,s conformity but it kept a good arch profile and made stable roadways but we were not at great depth

[Wheldale]

Dec 17, 2013 13:56:36 GMT -5 drgjs said:

Yes I can well imagine the pre-mechanisation - I am also quite involved with projects in the "narrow reefs" of south africa - gold and platinum. The ore bearing rocks are thin "seams" or "reefs". These mines are underground, very narrow spaces, dangerous and difficult. The miners carry all their stuff to the faces, drill holes manually  (jack hammer drills) into the rock face in two rows along the reef, about 1 meter deep, 30mm ir so in diameter, typically less than half a meter apart. Perhaps 200 at a time. Load and leave the mine for 4-6 hours while the fumes and dust clear. They are luck to break 80% of what the drilled and loaded. The supports tend to get blasted out and need putting back. They can only blast once a day. Have some pics if interested.

Going off topic a little, but on the topic of South African mining of reefs, usually the temporary supports are blasted out, the packs supports are solid and don't move. A good stope height for a reef is 1 meter, this is to minimise the amount of waste rock that gets sent to the mill. Most timber is transported to the stope on a mono winch, this is a small endless winch which when I worked out there most things were tied to it and sent into the stope. timber, hose, explosives etc. There is some carrying of equipment but its all part of the job really. Stopes were blasted once a day on the day shift, blasted material was cleared on the night shift. You could blast more if the ventilation was better, the inspectorate was very keen on the effects of blasting fumes. Main haulage drives were blasted once a day resulting in a 2 meter advance, but with permission from the inspectorate haulage drives could be blasted a few times a day.

[shropshirebloke]

Dec 17, 2013 11:23:02 GMT -5 drgjs said:

John,
well I never!
In my world people say to me mechanical methods would be highly inefficient.
[Since that makes my silly opening posts, well, actually nonsense, I've modified them.]
I've add a link to a couple of videos of coal blasts down under and in south africa
in the videos board.
So why the difference? Why do we use mechanical methods here but explosives down there?

John's already explained the economics part of it, but the safety bit is something else - I once found a sweating stick of Penobel in the back of a manhole. I reported it to our deputy and the next few minutes will stay with me forever. It was years later that I found out the procedure according to the M & Q Regs (evacuation of the area, loading into a dan full of dirt, etc, etc). - we crumbled it up, mixed it with dirt and dribbled it on to the belt.

Hey Ho!

[John]

Dec 17, 2013 17:34:54 GMT -5 shropshirebloke said:

Dec 17, 2013 11:23:02 GMT -5 drgjs said:

John,
well I never!
In my world people say to me mechanical methods would be highly inefficient.
[Since that makes my silly opening posts, well, actually nonsense, I've modified them.]
I've add a link to a couple of videos of coal blasts down under and in south africa
in the videos board.
So why the difference? Why do we use mechanical methods here but explosives down there?

John's already explained the economics part of it, but the safety bit is something else - I once found a sweating stick of Penobel in the back of a manhole. I reported it to our deputy and the next few minutes will stay with me forever. It was years later that I found out the procedure according to the M & Q Regs (evacuation of the area, loading into a dan full of dirt, etc, etc). - we crumbled it up, mixed it with dirt and dribbled it on to the belt.

Hey Ho!

Should have said "nowt" LOL

Pretty common practice for spare powder to be "cribbed" on the blind side of the belts in case of shortages in the early to mid 60's..I recall the stable hole men running out of powder to finish their shift off, they set off down the blind side of the belt looking for cribbed powder...About half hour later they returned....Shotfirer nearly had a heart attack when he fired the round...Boy was it a loud bang!! "Where the expletive did you get that powder from" He shouted, "from the rock headings down the road" Polar Ajax is what they used...I went down to the ripping lip, crawled under and guess what!!! There wasn't even a shovelful of coal for the stablehole men to clean up, the Polar Ajax did all the work for them.....

[John]

I might add for those that don't know, Polar Ajax is a powerful explosive, only it's not allowed to be used in coal or ripping lips.

[drgjs]

In keeping with Z theme, things seem to have doubled back on themselves in the reefs, Wheldale,
for various reasons. "cheap" explosives, labour force no longer prepared to be "cheap".

[shropshirebloke]

Dec 17, 2013 17:50:43 GMT -5 John said:

Dec 17, 2013 17:34:54 GMT -5 shropshirebloke said:

John's already explained the economics part of it, but the safety bit is something else - I once found a sweating stick of Penobel in the back of a manhole. I reported it to our deputy and the next few minutes will stay with me forever. It was years later that I found out the procedure according to the M & Q Regs (evacuation of the area, loading into a dan full of dirt, etc, etc). - we crumbled it up, mixed it with dirt and dribbled it on to the belt.

Hey Ho!

Should have said "nowt" LOL

Pretty common practice for spare powder to be "cribbed" on the blind side of the belts in case of shortages in the early to mid 60's..I recall the stable hole men running out of powder to finish their shift off, they set off down the blind side of the belt looking for cribbed powder...About half hour later they returned....Shotfirer nearly had a heart attack when he fired the round...Boy was it a loud bang!! "Where the expletive did you get that powder from" He shouted, "from the rock headings down the road" Polar Ajax is what they used...I went down to the ripping lip, crawled under and guess what!!! There wasn't even a shovelful of coal for the stablehole men to clean up, the Polar Ajax did all the work for them.....

I think it was "stashed" rather than "cribbed" round our way but I know what you mean John. Officially powder was either fired, signed over to the next shift (rarely a possibility), or carried back to the underground magazine - a long way at the time - so powder was stashed away and occasionally forgotten.

I've heard about Polar Ajax, but we only used Penobel and "Hydroproof" (not sure about the spelling but it was used for firing wet bottoms )