Skip sizes

[Wheldale]

Anyone know the biggest skip sizes used in the UK? I remember at Wheldale they were 6 tonnes, at Harworth I think 27 but could be wrong, is there any bigger ones?

[John]

Not sure who had the largest, but size is usually dictated by shaft Diameter. Although, one could install "long" skips as long as the headstocks were high enough to accommodate the longer skip at tipping level and the shaft was deep enough below onset level to accommodate the loading level.
Boulby Potash mine has 20 tonne skips, loading is at minus 30 feet below onset level.
I believe Cotgrave had ten ton skips, I think they started as 15 tonners, but due to the concrete shaft lining being eaten away and failing due to water bearing strata having acidic properties and having to be relined, reduced the shaft diameter.

[dazbt]

Skips are something that I've never been involved with, apart from a few occassions when I've rode up and down shafts in those that incorporated manriding cages. I do recall being told once a long time ago .... '1960s ish' that Monkton Colliery at Royston had the largest shaft winding capacity in Europe at that time, not sure what that capacity was or if it was infact a true statement but one shaft did have a four skip Koepe winding system installed at that time.
On thinking about shaft capacities and skip sizes I can envisage that John is right about the shaft diameters being one of the main factors in limiting capacity, especially in retrospective upgrades of the UK's older collieries, but in the 'newer' pits such as Harworth the shaft diameter would likely have been determined more by the expected capacity requirements rather than the initial cost of a 'quick sinking' as might have been the main influence in preparing coal mines of the previous century. Twenty seven tons of coal is a heap that I wouldn't want to have to shovel in a shift, or be dug out from under, but it does seem to be a pathetic amount of coal to be raised in one single lift, I have a feeling that drawing a meagre 27tonnes of gold ore at a yield rate of 3grams per tonne, in one lift wouldn't particularly suit the mine or international share holders of some South African Gold Mining Concern, I'll warrant that the gold mines of SA manage to formulate a better skip winding capacity.
Another factor of limitation has to be the drawing shaft depth, irrespective of the shaft diameter the engineering limitations of lifting any weight from depth must increase in direct proportion to vertical distance ............ just glad that I only had coal cutter related problems to struggle with.

[Wheldale]

My dad worked at Monckton, 6 shaft had 4 skips, not sure of the size but would be a hig output shaft as it was winding coal from the two Monckton mines.

I remember when I worked at West Driefontein GOld MIne, 6 shaft (were I worked the most) was made up of 3 shafts. 6 main shaft to a depth of 1400m had 20 tonne skips, 6 sub shaft (from 1400 to 2200m) had 20 tonne skips, 6 tertiary shaft (2200 to 3200m) had 6 tonne skips. West Drie was mining 10 grammes of gold per tonne of rock. about 4 million tonnes of rock a year being mines over 4 shaft complexes.

When I did my onsetter training at Leeudoorn Gold mine the main shaft was to a depth of 2000m had 20 tonne skips again. 20 tonnes seem to be the norm out there back in 98.

[John]

Although I maintained the skipping equipment at Boulby, I wasn't aware until this last week the winders were based on what is known as the "Blair" winding arrangement. ie multi rope split drum.
Sure I knew about the split drum and dual ropes and balance wheel on the top of the skips to accommodate rope expansion and stretch.

So was reading up on the Blair system. It was developed for deep shaft winding to reduce rope sizes and costs. As Daz mentioned, deeper the shafts, heavier hauling is a price to pay. So rather than one huge heavy expensive rope, they use smaller diameter lighter ropes. Cheaper and safety isn't compromised.

The paper I was reading was the engineering problems associated with shafts 4000 plus metres deep. One of the ways to haul mineral was to have a Blair system for half the depth, with a single rope hung below the skip suspending a skip for the other half of the depth. Sounds crazy I know, but has been designed!! Tipping would be mid shaft into a stage hopper and the other "top" skip would load and take that to surface discharge bringing another full skip on it's bottom set up to mid shaft.

Sounds pretty complicated until one sees a drawing of the mid shaft set up. But the system is due to go into operation in one of Western Deep Levels new shafts being sunk right now.
Now man riding is done on a similar set up, at mid shaft is a shaft inset where men descending the shaft are let off, they then go around the back of the shaft and climb on the lower deck of the opposite lower skip, and then proceed to pit bottom.

[John]

Just an afterthought, after a rope change, obviously we got rope stretch, one of the beauty's of the Blair system, was how easy it was to compensate for the stretch, as much as few feet in 24 hours!!

I'd get a call tipping had failed in pit bottom area, diagnosis was skip not lined up with proximity switch, too low. Once I'd established the problem, the winding engineman did a "clutching operation" ie brakes locked on the opposite motor side drum, declutch, and wind the driven side drum to take up a pre determined amount of rope. Stop, engage clutch and remove brakes from the none driven side drum. Took about 10 minutes and back in business once more for an hour or two.
This was done a few times a day for a week or so until the ropes had "been bedded in". First 48 hours were the worst though.

[dazbt]

Gleaned from the Internet;

"Auguste Victoria no. 7 shaft in Marl is a good example of a shaft that has been designed purely for high-performance coal conveying, that is to say skip winding. The installation’s pair of six-rope tower type winders are able to lift four skip conveyances each with a useful load of 33 tonnes. The drive motor and driving sheave are positioned immediately above the mouth of the shaft. This arrangement saves space, as no additional buildings are required on the colliery surface. The skips race up and down the shaft at a speed of 16 metres a second and can deliver 1,900 tonnes of raw coal an hour to the pit head.

and

Majialiang mine south of Datong China
The mechanical components will be supplied by Siemag M-Tec². The larger of the two winders is equipped with a 3,600-kilowatt synchronous motor and enables a double cage with a payload of 50 tons to achieve a speed of 9.97 meters a second."

[John]

Feb 25, 2010 10:31:55 GMT -5 dazbt said:

Gleaned from the Internet;

"Auguste Victoria no. 7 shaft in Marl is a good example of a shaft that has been designed purely for high-performance coal conveying, that is to say skip winding. The installation’s pair of six-rope tower type winders are able to lift four skip conveyances each with a useful load of 33 tonnes. The drive motor and driving sheave are positioned immediately above the mouth of the shaft. This arrangement saves space, as no additional buildings are required on the colliery surface. The skips race up and down the shaft at a speed of 16 metres a second and can deliver 1,900 tonnes of raw coal an hour to the pit head.

and

Majialiang mine south of Datong China
The mechanical components will be supplied by Siemag M-Tec². The larger of the two winders is equipped with a 3,600-kilowatt synchronous motor and enables a double cage with a payload of 50 tons to achieve a speed of 9.97 meters a second."

I wonder why a synchronous motor over DC system???
Prior systems used the Ward-Leonard system, gave good speed control and then prior to that slip ring motors for speed control, pretty inefficient though.

[dazbt]

Feb 24, 2010 15:07:16 GMT -5 Wheldale said:

My dad worked at Monckton, 6 shaft had 4 skips, not sure of the size but would be a hig output shaft as it was winding coal from the two Monckton mines.

I remember when I worked at West Driefontein GOld MIne, 6 shaft (were I worked the most) was made up of 3 shafts. 6 main shaft to a depth of 1400m had 20 tonne skips, 6 sub shaft (from 1400 to 2200m) had 20 tonne skips, 6 tertiary shaft (2200 to 3200m) had 6 tonne skips. West Drie was mining 10 grammes of gold per tonne of rock. about 4 million tonnes of rock a year being mines over 4 shaft complexes.

When I did my onsetter training at Leeudoorn Gold mine the main shaft was to a depth of 2000m had 20 tonne skips again. 20 tonnes seem to be the norm out there back in 98.

Wheldale, have you got a copy of the book by P.A. Thorpe, "Monkton it's Origins and History", first published in 1997?
I only guessed at the 3grams/ton gold content, I think I once read that figure as being the reclamation expectations from an old copper mine spoil. Obviously the 10g/ton was viable when you were working in SA ....... must be even better with today's gold prices. Did that yield ever increase by very much or was it fairly consistent?

[Wheldale]

I have a copy of the Monckton book, says very little of the reconstruction in the 50's. My family worked there before it closed. My Grandad was there for 40 some years.

When I was at West Drie the average yield in 98 was 10 grammes a tonne. Some sections were as low a 2 grammes, some as high as 200 grammes a tonne. When the price of gold was really low Goldfields started going through the old dumps. This was quite profitable at around 3 grammes a tonne.

West Driefontein has produced more gold than any other mine in the world, this being over 2000 tonnes of gold.

[philipford734]

Bradford Colliery, Manchester had 12 Ton skips in the main coal winding shaft.

[holty]

Feb 24, 2010 15:08:50 GMT -5 John said:

Although I maintained the skipping equipment at Boulby, I wasn't aware until this last week the winders were based on what is known as the "Blair" winding arrangement. ie multi rope split drum.
Sure I knew about the split drum and dual ropes and balance wheel on the top of the skips to accommodate rope expansion and stretch.

So was reading up on the Blair system. It was developed for deep shaft winding to reduce rope sizes and costs. As Daz mentioned, deeper the shafts, heavier hauling is a price to pay. So rather than one huge heavy expensive rope, they use smaller diameter lighter ropes. Cheaper and safety isn't compromised.

The paper I was reading was the engineering problems associated with shafts 4000 plus metres deep. One of the ways to haul mineral was to have a Blair system for half the depth, with a single rope hung below the skip suspending a skip for the other half of the depth. Sounds crazy I know, but has been designed!! Tipping would be mid shaft into a stage hopper and the other "top" skip would load and take that to surface discharge bringing another full skip on it's bottom set up to mid shaft.

Sounds pretty complicated until one sees a drawing of the mid shaft set up. But the system is due to go into operation in one of Western Deep Levels new shafts being sunk right now.
Now man riding is done on a similar set up, at mid shaft is a shaft inset where men descending the shaft are let off, they then go around the back of the shaft and climb on the lower deck of the opposite lower skip, and then proceed to pit bottom.

[holty]

To John who worked at Boulby Potash. Is John Chapman from AMCO still at the mine or has he retired. He was at Thorne when I started with AMCO in 1989.

[John]

Jan 6, 2011 16:23:53 GMT -5 holty said:

To John who worked at Boulby Potash. Is John Chapman from AMCO still at the mine or has he retired. He was at Thorne when I started with AMCO in 1989.

I left in August 1979 and the only Chapman I knew was my mate Phil on "B" shift.

[kennygeorge]

Skip sizes depended in most cases on existing shaft criteria.
Our skips were only 4 tons payload which gave us a hourly lift of 250 tons per hour.
Our old existing shaft was 13ft 6" in diameter, then of course you dress the shaft space becomes limited. We employed flexible rope guides plus two buffer ropes as mid shaft the skips were only 3 1/4" apart. It worked well for us, but there were infrequent " touches"
A further consideration to be considered was our coal prep plant capacity was 240 tons per hour, so we were at the limit there also
Regards Ken

[garryo]

Skip sizes

With regard to the NCB, the board standardised on 20 ton skips and counterweight on tower mounted friction winders when winding from multiple levels and twin 10 ton skips when winding from one level, Some shafts such as Cotgrave had twin 10 ton skips and counterweights.
Westoe (Crown shaft) and Wearmouth (D shaft) had single 20 ton skips and Cws.
New Monckton No6 was originally designed as a twin skip and counterweight system with GEC 2250HP DC motors. Not sure if 2nd winder was installed in the tower. Last time I saw the tower in the 70s it looked pretty big (although abandoned).
Grimethorpe No3 was a two rope ground mounted friction winder with two 13.2ton skips while Harworth tower has twin 27.5 ton skips driven by 4000kW motor and the largest in the UK (coal) I think is Maltby No3 shaft which has a two two mounted winders each with twin 25ton skips driven by 3000kW motor giving a capacity of 1,400ton/hour. (Harworth still largest single skip).

Benifits of a slow speed cyclo-converter fed winder over a DC thyristor drive is given as "no brushgear and commutator and in theory no limit to motor size amongst others".
First cycloconverter winder was tried at Wearmouth colliery A shaft where an existing AC 375kW slipring motor was replaced by an induction motor and cycloconverter in 1986.
Now at Sunderland instead of a cycloconverter they have a Stadium of Light, well folks thats progress!

[John]

Cotgrave started out with larger skips, 15 tons?? But due to a shaft lining failure caused by acidic water from the gypsum strata attacking the concrete, the shaft had to be refrozen through the Bunter, (Sherwood sandstone) and relined with an acid resistant concrete, thus being a much smaller diameter shaft. I think steel linings or tubbings were also added. I'll have to send a message to my old chum Clem to corroborate that one.

[John]

Word back from my old mate is he can't recall the diameter of the shaft after relining.

[bulwellbrian]

I think Cotgrave shafts had to be relined before production started. I think they were still sinking the shafts when the problem occurred. hence they were not fitted out at the original diameter.

[John]

Feb 16, 2012 8:24:03 GMT -5 bulwellbrian said:

I think Cotgrave shafts had to be relined before production started. I think they were still sinking the shafts when the problem occurred. hence they were not fitted out at the original diameter.

The story I was told Brian, was a Sunday dayshift Deputy/s and onsetters rode down the downcast shaft and when they arrived at pitbottom, it was awash with water. The onsetter reached through and rang them back up the pit again. One of the Deputy's set out to borrow a canoe or small row boat to take down to locate where the water was coming from.
2nd trip down with said boat, a couple of them rowed around found nothing, so went to the upcast pit bottom and water was cascading down the shaft.
As you say, I don't think they were in production either but still developing the main roads both north and south.
After it was determined they had major problems, the Manager was trying to locate pumps large enough to cope with the water coming from the shaft failure, the only people with pumps on that scale were the Royal Navy.
Again, this is what I was told, after the shaft was relined, new smaller skips had to be employed as the original 15 ton's? were way to big for the newly lined shaft.
An old mate, who sadly passed on a couple of years back, told me the shaft failure was due to water that had turned acidic due to the gypsum strata in the area. Trev served his apprenticeship at Cotgrave during shaft sinking and early development, he transferred sometime around 1966 or thereabouts to my old pit.
Pity I didn't question him some more......Hindsight again...