Riccall Mine roof bolting standards board situated in concourse.
Once the Selby Coalfield mines received the required exemptions to use rockbolts as a primary support system from the H.S.E. each individual mine had a legal requirement to have a Rockbolting Co-ordinator to supervise the systems of routine monitoring and maintain high standards for the installation of rockbolts. This operational standards board was situated in the concourse area of the mine and visible to all of the men for reference. Extremely high standards of roof bolting were expected during the bolt installation to prevent roof falls and to mitigate future problems and repairs during production. Below are the photos explaining the issues encountered when using roof bolting as a support system.
Shear Break or Guttering Developing.
This can lead to total roof failure and can cause failure of the roof on the face.
Bolthead broken off and strap tearing.
This may lead to localised roof failure.
Overloaded side bolts end plates.
This is due to high immediate rib movement on installation.
Dome plate inverting.
This is a sign of strata movement within the bolted length and or resin loss on installation.
Immediate roof bulking.
Caused by the roof being squeezed in areas of high horizontal stress.
Failed of bolt in excess of 100m of thread.
Probably caused by wrong nut size, low air pressure, poor resin or faulty gopher drilling machine.
Broken strap.
Due to roof being squeezed in areas of high horizontal and vertical stresses.
Floor blow.
Associated with high vertical and horizontal stresses mostly common due to direction of drivage with relationship to major stress line and or face retreat.
Failed bolts with immediate roof bulking, straps shortening, angled bolt and gap in roof mesh.
Caused by incorrect cutting horizon in this case.
Good roadway standards due to good supervision, high standards of bolt installation, correct cutting horizon and early additional support of roadway.
The control measures for most of the issues shown were installation of extra roofbolts, strussed cable bolts, wooden legs, steel supports or Fibcrete stacks.
Plan above showing Riccall Mine south side faces showing faulted area on H443s coal face panel.
During the development of H443s face in August 1988 a section of sandstone intrusions appeared in the heading at 730m mark. These intrusions continued for over 100m and then disappeared. The decision was made to continue with the headings to full distance and start the face as planned at 1600m mark. As the face retreated a plan was created to transfer the equipment onto a new face line which bypassed the faulted area and continue with the face. The loss of production was a problem but another issue was on the horizon which was the royal visit by Queen Elizabeth and Prince Phillip planned for the 9th December 1989. Below is the step by step planning document created by the management team overseen by Denis Allchurch, Riccall Mine Deputy Manager and all the departments responsible at the mine for the timely and safe transfer of equipment from one face to another.
Covering description from Denis Allchurch
Acknowledgementsof staff
Critical path analysis
Bolting and meshing
Building new shearer and dismantling existing shearer
Maingate move out
A.F.C. salvage, cables and hoses
Powered supports
Electrical co-ordination
As you can see from the booklet above describing the face to face transfer, the process of moving thousands of tonnes of equipment in such a short time is incredibly difficult. Organisation and briefing with experience and input from all the staff is the key to safe working. As you can see from the mine plan at the top of the post the face ceased shearing coal on 11th October 1989 and the new face was shearing coal on 7th November 1989. The transfer left a month for the face to be established before the Royal Visit.
Many thanks to Denis Allchurch, Riccall Mine Deputy and later Mine Manager for the information in this post.
I have been talking to Andy Mortimer who was an assistant surveyor at Gascoigne Wood Mine from 1981 until 1989. Here are a few of his memories. His information shows how technically difficult the development of the 12.2 km spine tunnels, which were the backbone of the Selby Complex, were to complete.
Andy did his training as a surveyor at Glasshoughton Colliery between 1975 until 1979. From the ending of his training until 1981 he was an assistant surveyor at Saville Colliery and Gascoigne Wood Mine working at both sites for two years. He was promoted at Gascoigne Wood in 1981 as an assistant surveyor supervising the South Spine Tunnel project until completion in 1988.
When he started at Gascoigne Wood the drifts were nearing completion and the two specially designed tunnel shield Dosco SB600s, used to sink the circular drifts were about to be removed and replaced with Dosco Mk3 roadheaders. These machines developed the spine tunnels up to the installation of the Robbins T.B.M. in the south tunnel at 1600m mark and the subsequent installation, at 2891m mark, of the Meco Titan E134c Roadheader in the north tunnel.
When the drifts reached 794.6m mark the surveying team set the angles of further tunnelling to a line of a 4000m curve to gain the correct level for the installation of the spine tunnel conveyors. This curve ended at 836 metre mark in the South Spine Tunnel and 833m in the North Spine Tunnel.
Bottom of Gascoigne Wood Drifts showing the start of the spine tunnel developments
The tunnels were then driven in the Lidgett Seam which is approximately 65 metres below the Barnsley seam at a gradient of 1 in 33 heading east. This level gave the correct depth for the future staple shaft bunker installations at the individual pits. The roadheader progressed well up to the 1600m mark using 17 x 12 ft arch support girders. This was the point where the Robbins TBM erection chamber was constructed in the South Spine Tunnel. The North Spine Tunnel Dosco Mk3 Roadheader progressed at around 65m per week to achieve the first connection with Wistow Mine.
Gascoigne Wood spine tunnels showing connection to Wistow Mine
The Robbins 193-214 Tunnel Boring Machine erection chamber was created in three separate part using benching of the strata due to the sheer size of the 240 tonne machine. After the initial cuts were completed and square section girders with shutterings were installed the top section of the chamber was concreted with heavy duty lifting beams installed to handle the weight of the machine sections. The middle 2.5m section was cut and concreted. The lower 2m was cut with a semi circular base to allow for the 5.8m circular cutting head to be installed. When completed the chamber was over 40m in length, 6.8 metres wide and 8.6 metres high.
The Robbins T.B.M.Erection Chamber
The Selby Coalfield was designed and developed using the very latest mining technologies and equipment. Gascoigne Wood mine development was no exception. Flameproof laser beams were used in the underground tunnels by surveying teams for complete accuracy from the start of the mine. The lasers were very heavy pieces of equipment and were mounted in the left of centre in the roadways. The large mounting brackets were manufactured from girders and needed four, two metre roof bolts to anchor the equipment in the roadway. During the early use of the lasers it was realised that in dusty conditions the integrity of the beam was diminished. The beams were refocused by the manufacturer to give a sharper, intense beam for surveying to take place. The lasers had to be moved forward every 150 metres, which was often less than a week due to the rapid development speeds in the Robbins TBM South Spine Tunnel.
The surveying team at Gascoigne Wood used various systems to cross reference and ensure the accuracy of the spine tunnels. All the Selby mines were referenced to the Ordnance Survey Grid Reference System which is known as the British National Grid (B.N.G.).
Gascoigne Wood Mine
Gascoigne Wood Mine had a marker point beacon on the covered stockyard (marked Coal preparation plant on photo) with other points in the area being on the top of the winders at each of the five satellite mines marked with flashing beacons for reference. Carlton Towers, Pontefract Water Tower, Sherburn Church and York Minster were also reference points in the area. Andy ‘fondly’ remembered carrying huge batteries up to the top of the 72m high main tower at York Minster, through the very tight internal staircase, to power the beacon.
York Minster Towers
He then set up a tripod with a theodolite and measured to the flashing beacons on the winder towers at the satellite mines and the covered stockyard at Gascoigne Wood. This process was repeated at each pit to achieve the triangulation surveying readings.
North Selby Mine Winder Towers
These surface reference points along with the huge amount of borehole depth, shaft depth data and use of the laser beams ensured the accuracy of the spine tunnel developments.
As the spine tunnels progressed connections were made to Wistow Mine for ventilation and the coal clearance system which was operating from January 1983. Ventilation slits were also made between the spine tunnels to improve the working conditions in the headings. The plan was to connect to Wistow, Stillingfleet and Riccall mines for ventilation and coal clearance.
Spine tunnels between Wistow connection and Stillingfleet Bunker 5 and 6
As the spine tunnels progressed past the second ventilation shaft from Wistow at 7916m mark the next planned ventilation connection was Stillingfleet Bunker 5 and 6 at a gradient of 1 in 12.9 towards the east. During this stage of development in the South Spine Tunnel the extreme temperatures were getting increasingly difficult due to distances from ventilation boreholes. The heading teams were increasingly suffering with heat stroke with men collapsing on multiple occasions and had to carry up to 10 litres of water to get them through the shift. At the back of the pantechnicon a water storage tank for the TBM cutting water was sited. Andy used this on occasions to cool his arms when having the signs of heatstroke as it was slightly cooler than the ambient temperature of over 45° centigrade. Incredibly the teams operating the Robbins machine achieved tunnelling rates in this period which culminated in a world record breaking week in January 1986. 19m in one shift, 43m in one day and 152.3m in a week.
The world record breaking AMCO Heading Team January 1986.
Due to the high cutting speeds of the Robbins TBM machine, the North Spine Tunnel Titan E134c Roadheader was unable to maintain the same rates and started to lag. Due to the unavailability of ventilation slits and problems with the ventilation connection road from Stillingfleet Mine at Bunker 5 and 6 the South Spine Tunnel heading was nearing the limits of the available air flow from a single leg ventilation.
In early 1987 the Robbins TBM machine hit an area of very soft ground. The development stopped for a few weeks for remedial work. At this point a tunnel was started from Riccall Mine called the Stillingfleet Connection running above and parallel with the projected South Spine Tunnel. When this roadway was completed a 1 in 1 drift was driven down to the South Spine Tunnel using 10 ft x 8 ft arch girders to give a ventilation connection with Riccall Mine. The Robbins TBM went onto complete the South Spine Tunnel on the 22nd June 1987. Andy supervised the surveying work and completion of the Riccall Mine No 7 and No 8, 7.5m diameter 60m deep staple bunkers and bunker slits. The Robbins 193-214 Tunnel Boring Machine continued driving forward at the completion of the development and was abandoned.
The completed spine tunnels at the Riccall bunker connection.
Andy went on to work at Riccall Mine for six months and then gained promotion to Kellingley Colliery in 1989 as Deputy Surveyor and then Unit Surveyor where he stayed until the closure of the pit in Dec 2015.
Many thanks to Andy Mortimer for his time and information provided for this post.
Setting up structures and systems for the management of a multi billion pound project such as the Selby Coalfield was a very complex task. After buying the land for the sites of the five satellite mines and Gascoigne Wood, which was the largest site with two surface drifts, coal handling plant and railway loading facilities, a team of surveyors, which is a statutory role at a mine and surveying staff were needed at each site. They were managed from North Yorkshire Area H.Q. at Allerton Bywater.
The first two pits to be sunk were Gascoigne Wood and Wistow Mines. Gascoigne Wood drift tunnelling started in March 1978, Wistow No2 shaft sinking started Jan 1978 and Wistow No1 started in June 1978. As you can imagine a huge amount of surveying preparatory work was carried out on the sites before any sort of construction could take place.
Initially the surveying of the sites were organised from North Yorkshire Area H.Q. where the Selby Coalfield Project Team was set up. Two surveying teams were created called East Side to survey North Selby, Riccall and Whitemoor mines and the West Side to survey Gascoigne Wood, Wistow and Stillingfleet mines. Each team had a surveyor, assistant surveyor and a linesman team. The head surveyor for the Selby Project was Tony Shirley and deputy surveyor Dennis Aitchison.
As the site construction progressed and the sinking of the two shafts on each site were under way, the workload increased massively.
The teams at each mine were created and included a unit surveyor and two assistant surveyors. These posts were advertised nationally in the NCB as new roles open for promotions of existing members of staff as were the management roles within the complex. A team of linesmen and support staff were transferred from closing collieries. Surveying offices were also built on each site.
When the surveying teams at each of the six individual mines were created the East and West Side teams responsibilities were handed over to the new teams at each mine as the site development progressed. The Selby Project team was wound down in 1984.
Tony Shirley, who had been surveyor in charge of the Selby Project was promoted to North Yorkshire Area chief surveyor and the existing chief surveyor, Eddie Garner retired.
Many thanks to Dave Wilson who provided his time and the information in this post. Dave did his training to be a surveyor at Rothwell Colliery and applied as an assistant surveyor working under unit surveyor Jack Donachie at Stillingfleet Mine. He started in 1984 and was later promoted to deputy surveyor. He worked at Stillingfleet until 2003. He worked in outside industry and returned to mining at U.K. Coal at Howarth Park in the planning department in 2008. As the industry wound down he transferred to Kellingley Colliery as mine planner until closure in Dec 2015. He now works at The Mining Remediation Authority.
The Selby Coalfield was designed and planned to produce 10 million tonnes per annum when in full production from the five pits. This figure meant that each pit had to maintain 40,000 every single week which was no mean feat. The first year this figure was exceeded was in 1992/1993 when the complex produced 10,806,000 tonnes of coal in the financial year ending March 1993. Wistow Mine produced 2,938,000, which included a European record of 173,156 tonnes in one week, Riccall Mine 2,600,000, Stillingfleet Mine 1,506,000, North Selby Mine 2,024,000 and Whitemoor Mine 1,801,000 tonnes of coal. These figures were an outstanding achievement with records for production and tunnelling broken on a regular basis. Twenty two longwall, two shortwall and 13 single entry faces were worked in this financial year.
As the coal production was ramping up, face development rates had to improve which was achieved by the introduction of rockbolting throughout the complex. Nearly 59,500m of tunnels were developed in the financial year 1992 /1993 to open up the coal faces needed to mine over 10,800,000 tonnes of coal production. All in all a good year for the Selby Coalfield.
In the year 1993/1994, the complex was set up for another record year and produced 12,091,000 tonnes of coal. In this year, Riccall Mine produced a European record of 3,060,000, achieving an average production of nearly 60,000 tonnes every week.
During the year, Riccall Mine worked three faces at the west of the mine. H474s, H475s and H476s were all 250m in length and retreated over 2000m. Three faces were worked at the south west of the mine. H430s, H432s and H433s were 230m in length and retreated over 1500m. Three faces at the east of the mine, H501s, H502s and H503s were all 250m in length and retreated 1800m. A total of five, face to face transfers of equipment were completed during this twelve month period. This was a very busy year of seven days a week and twelve hours shifts for the teams, including the electrical installation team of which I was a member.
Pete Wordsworth and Ian Lloyd with West Side face team.
The lads on the photo are Pete Wordsworth who was Top Nana( Face Deputy ), Ian Fisher, Ian Lloyd (Under Manager), Mark Light, Maurice Kent, Don Cook, Unit fitter, Richard Yarrow (Teapot), Simon Craven, Stuart who was a chock fitter (Mr Blobby) Terry Haywood, John Barnfather, Dennis Nicholl.
Above is the press release from Selby Area Director Alan Houghton confirming the European Record of 1,000,000 tonnes in 14 weeks and 3,000,000 tonnes in 51 weeks.
Wistow Mine produced 2,900,000 tonnes, Stillingfleet Mine produced 1,952,000 tonnes, Whitemoor Mine produced 2,221,100 tonnes and North Selby Mine produced 1,853,000 tonnes of coal. Twenty six longwall, two shortwall and ten single entry faces were worked and over 58,000 metres of tunnels were developed during this year.
This was the final year that British Coal managed the coal industry with RJB Mining taking over in Jan 1995.
Since coal mining began the roof in a mine was supported to ensure the rock strata over our heads didn’t collapse onto our heads. This was initially achieved by setting wooden props from the floor to the roof to stop the strata moving, fracturing and collapsing, often with catastrophic results. For hundreds of years this simple system was used often in conjunction with wooden bars set over the props to span roadways.
Prop and bar
Steel support joist, known as girders or arches were introduced due to their greater inherent strength. Many types of mining arches, square section girders and joists were developed for different seams, conditions, weight, speed of setting and cost. The roof above the girders were usually covered with corrugated steels sheets to stop rock falling onto the men. The Selby Coalfield, which worked the gassy Barnsley seam was slightly different in that open steel mesh was the only coverings allowed above the supports. This ensured full access to the roadway and ensured it could tested for methane without hidden pockets behind steel sheeting.
Gascoigne Wood North Spine tunnel
Gascoigne WoodSouth Spine tunnel
Steel arches in H504s T/G at Riccall Mine
Using roof bolting as a primary support system for strata control was developed in the U.S. during the 1940s and into the 1950s. They were initially used to replace wooden props and bars used in the American mines and was thought as a more effective and safer system of roadway support. Roof bolting as a secondary support system to supplement flat top girders was used with great success at Hartley Bank Colliery at Netherton, Wakefield as early as 1953 on both headings and longwall roadways.
Legislation stated that rockbolts may only be used as a principal support system in a coal mine if the H.S.E. has granted an exemption from the requirements to set recognised authorized supports. An exemption was only given if the roofbolting system was tested and proven at each individual mine to be safe and a geotechnical assessment and site investigation was carried out by a suitably qualified and competent person.
Below are the requirements to be taken into account when carrying out the site investigation;
Geology: including the strata section, rock properties, faults, cleat, parting planes, presence of water or any substance likely to flow, borehole information and gradients. All factors need to be correlated relative to the mining horizon;
Stress: the direction and magnitude of the stress field components for pre mining, mining induced conditions and interaction;
Pillar design and effects: the assessment needs to include drawings and diagrams to illustrate potential risk areas;
Environmental effects: the effects of ambient temperature, mine water and associated impurities.
Bond strength: measured by short encapsulation pull tests using the proposed rockbolting materials and components. The tests need to be carried out for all major roof horizon changes within the length of the proposed rockbolt and the effects of wet flushing or alternative dust control system on the bond strength determined.
Standup time: dilation related to distance from the face.
Information taken from H.S.E. guidance on the use of rockbolts to support roadways in mines.
In the early 1980s Allerton Bywater Colliery used roof bolts in the Middleton Little seam on 56Bs district, as part of a trial, when mining small panels of remnant coal referred to as finger panels and proved a great success. A consequence of the trial and the technical information gained, they became the recognised experts and leaders of roof bolting in the U.K. The introduction of totally rockbolted supports was introduced on 56As which was the next panel to be worked.
This system of roof support was used in the Selby Coalfield in early 1986 when HO2DRs, one of the first two faces at Riccall Mine were developed. D2s tailgate was a trial using rockbolts in conjunction with flat profile arches using a Lee Norse LN800 1TT continuous miner.
Lee Norse LN800 1TT continuous miner.
Rockbolting was introduced as primary supports at Wistow Mine in 1990 due to difficulties with the geology at the mine.
During the development of the Selby Coalfield new technologies were introduced very quickly as they became available. Roof Bolting was one of these system to revolutionise the speed, cost and safety of roadway developments initially on coal face access roadways. As the technology and monitoring was improved, main lateral roadways and face support salvages, which were previously supported by girders, became supported by roof bolts and cable bolts.
Roofbolting used for face support salvage at Riccall Mine.
Stopping roof collapses in a coal mine was always seen as spanning the gap created when coal or rock was removed by setting a support in this void therefore holding the roof up from below. Roof bolting and cable bolting are a completely different way of looking at this problem. Roof bolting uses the inherent strength of the strata situated above the roadway as a support. A hole is drilled to specified length and diameter into strata which has the required strength passing through the weaker layers of strata. Resin adhesive capsules are entered into the drilled hole and a steel bolt is then inserted. When the bolt is rotated and forced into the hole, by action of the rock drill, the resin capsules and hardening agent are mixed and fill the gap between the bolt and strata, known as the annulus. This creates a solid bond between the bolt and the surrounding strata. When the bolt is fully entered the nut is tightened onto a flat plate against the roof and tensions the bolt which holds the strata together. If this process is carried out quickly after the roof is exposed during mining process, the bolts and resin hold the strata together ensuring no bed separation of the rock and no roof falls occur.
The roof bolts used at Riccall Mine were threaded high tensile steel with a diameter of 22mm and were 2.4 metres in length. The roof bolts were installed into a 27mm drilled holes using two part high strength polyester resin. The resin capsules used were colour coded red for quick setting and green for slow setting. Two slow and one quick setting capsules were inserted into the holes and the bolt was drilled into the hole using a compressed air drill known as a ‘Gopher’. The drilling action and the sharp wedge tip of the bolts punctured and mixed the resin capsules which created a very powerful bond between the bolt and the surrounding strata. Once the bolt and resin are set to an adequate strength the 24mm nut is tightened on to a conical insert and plate up to the roof.
This system of rockbolting became standard throughout the Selby Coalfield and was used in conjunction with either W bars or flat straps with 1m spacing holes across the section of roadway. Each support was set at a 1.2m spacing. Steel or plastic mesh was used as part of the support.
To apply for an exemption to use fully rockbolted roadways many test were carried out. Roof / Strata movement measurement, rockbolt strength tests, rockbolt pull test and strain gauge tests which were all designed to check the performance of the rockbolt /resin/ rock system. Below are the areas of a mine where rockbolts may provide principle support;
Development headings and junctions; Coal face development drivages; Retreat district gate roads including the face ‘Tee’ junction; Room and pillar coal production districts; Special purpose drivages, eg to house equipment.
Four examples of places which may not be suitable are: Goaf scours; Gate roads serving advancing faces; Cross measures drifts; Headings formed by shotfiring off the solid.
Once a safe system has been designed and tested through the four stages of acceptance, the exemption to use rockbolts as a primary support is granted. The Mine Manager and Rockbolting Co-ordinator were required to instigate a system of routine monitoring and recording called the’ Scheme for the routine monitoring of roadways’
The system of monitoring included visual indentification of roof movement called dual height telltales.
Dual height telltale showing general assembly
The telltales were installed in the rockbolted roadway at intervals not greater than 20m apart. They were drilled to a height of at least twice the height of the rockbolts and basically monitored the movement of the strata above the roadway. Two spring loaded wires were anchored into the strata above the roadway and were given a copper tube set at the roof height as a reference point. If the strata moves downward the telltale will move upward and gives an indication of movement in millimetres. The telltales are monitored on a shift basis and recorded by the district official. Any movement is recorded. Excessive movement (25mm) must be reported to the senior official and action taken to remediate the movement should be carried out quickly.
Multiwire-extensometers were used and acted in a similiar manner to dual height telltales. This system used a four wire system set at four levels in the strata in a 7m hole and were set at 200m intervals in a roadway. This system is recorded by suitably trained people and could be tested manually or by remote electronic systems and was part of the ongoing roadway monitoring system.
Multiwire Extensometer
Information taken from H.S.E. guidance on the use of rockbolts to support roadways in mines.
Fully rockbolted headings became very common in face developments in the early 1990s, as different types of continuous miners which were ideal for rectangular section roadways were introduced throughout the Selby Coalfield. BJD(Jeffrey) Heliminers were used at Wistow and Stillingfleet Mine’s. Whitemoor Mine introduced Joy CM12s with North Selby and Riccall Mine’s used Lee Norse LN800 machines.
Rock bolted heading at Riccall Mine
Fully rockbolted headings were introduced at Riccall Mine in July 1991 on H474s and June 1992 on H430s. During the H430s face development in mid 1992, the teams set a European record of 180m of development in a week using a Lee Norse LN800 continuous miner using the fully roofbolted system. This record was surpassed many times at various mines throughout the complex as the system was perfected.
H473s tailgate showing rockbolted heading with arches as primary support
Stanley Main SM501s tailgate showing roofbolting and plastic side meshing. Glenn Bryan is carrying out methane boring using an EDECO mobile drill rig( Moonbuggy) in the photo.
When a roof support rockbolt is used for lifting or slinging the load must not be greater than 1 tonne.
If bolts are needed for lifting of greater loads, specially installed bolts called anchor bolts (we called them spot bolts at Riccall Mine) along with suitable colour coded lifting shackles should be used. They must be identified as lifting bolts with safe working loads shown.
When the Selby coalfield was planned one of the first major issues to be raised was the East Coast Main Line running over the planned workings of Riccall Mine and Stillingfleet Mine. The concern was that a mile wide section of coal would have to be left to maintain the integrity of the railway. This would have cost the N.C.B. a huge amount of time and money due to lost available reserves and having to plan a mine around the mile wide pillar of coal. Thirty coal faces would have been affected had the line not been moved. As with most mining projects a solution was found. The solution was to move the railway line to the west of the Selby Coalfield. This was called the Selby Diversion. Below is an amazing insight into this marvel of engineering within a marvel of engineering.
The new 13.79 mile Selby Diversion line was built between 1980 and 1983 to the very latest specifications. In 1983 the old line was abandoned. A new section of the A19 road was built on the old railway from a new roundabout sited at the south of Barlby near to British Oil Cake Mills (BOCM) factory and pickle factory to the north of Riccall. This created a much needed bypass of the villages and was opened in October 1987. The abandoned railway at the north of Riccall became a part of the Trans Pennine Trail cycleway to York as part of the Sustrans scheme.
My thanks to Neil Rowley for providing all the information in this post. This is an article that Neil wrote for a mining history society a few years ago. He has kindly shared ‘A Day in the Life of the Selby Complex’ from when he was Deputy Manager at Gascoigne Wood Mine.
A Day in the Life of the Selby Complex
Wednesday 29th May 1996
Gascoigne Wood Mine 1996
Cable Belt Inspection
Underside of ASL conveyor showing spillage
Map 1
Approximate Location of Working Faces and Main Conveyors in May 1996 (Surface/Underground correlation is by personal estimate and is for general interest only)
Area covered by Planning permission approximately 100 square miles
Introduction
Whilst clearing out my garage recently I found a folder of reports dating from 1996. At the time I was Deputy Manager at Gascoigne Wood Mine. The reports relate to the daily operations of the Selby Coalfield as seen from the control room at Gascoigne Wood.
I feel that these reports give good insight into the day to day working of a huge industrial complex which is now quickly receding into history.
The complex was made up of five producing mines with one common coal clearance system which brought the coal to the surface at Gascoigne Wood. Map 1 is adapted from an early brochure illustration and shows the general layout. Note that this early base map shows the East Coast Main Line running north/south through the centre of the mining area. Before coal production commenced, the railway was rerouted to the west of the production area to avoid subsidence issues, an example of the grand scale of the project. When I commenced my employment at the complex in 1980 I was told that it should have a life of 25 years, a surprisingly accurate prediction as final closure occurred in 2005.
All coal production from the complex at this time was from the Barnsley seam and the mining system employed was mainly retreating longwall.
The Reports
Each individual mine in the complex would have its own detailed daily reports but as Gascoigne Wood was the point at which all coal came to the surface to be prepared and dispatched, the GW reports needed to contain some basic information from each of the producing mines in order to enable fair allocation back to the individual mines of tons produced. Their operating budgets depended on it!
I chose a date of 29.5.1996 at random to illustrate the operation and sheer size of the complex. At the time the complex was owned by RJB Mining. Privatisation of the industry having taken place in late 1994.
Report 1 is the Daily Production Record for this date.
Safety was taken very seriously and reports generally commenced with this aspect.
It can be seen that there had been one minor accident at Gascoigne Wood during the day. A man had received an injury to the roof of his mouth from a sharp object. This somewhat unusual incident would have been discussed in some detail at the Manager’s morning meeting.
Then on to the production reports.
Wistow Mine had three producing longwall faces on this date. H92s was at the deeper end of the Wistow take and was of conventional length. H74s was shallower and hence shorter to control subsidence to within agreed limits. H134s was very short. Hence H92 could achieve 15.8 strips in the day, 74 managed 17.4 but 134 amassed 30 very short strips.
Riccall Mine had two faces. H478s was successfully mining an area to the south of Riccall village. H504s had just come into production a couple of weeks earlier. This may account for the lower than expected number of strips. It was located to the east of the shafts under Skipwith common.
Stillingfleet Mine had two faces both performing well. H302s was mining the area to the west of Escrick Brick Works. H266s was mining the area to the South of Naburn Lock.
Whitemoor Mine was operating two faces. H641s was to the south of the Whitemoor shaft pillar and H632s was north of North Duffield village. The low number of strips combined with the high ash content that we see from other reports suggests that the faces were in faulted areas and suffering from roof control problems. Depth below the surface of these workings was approximately 900m.
North Selby Mine was the deepest of the Selby mines and was producing from two faces. H906s was to the East of the shafts working at a depth of over 1000m. H856s was near Deighton village. Both seem to have been performing pretty well on this date. As a rough estimate I would say that the coal from H906s face had an underground journey of over 20Km through the conveyor system of the complex before it reached the surface at Gascoigne Wood.
Total mineral transported to the surface via the Gascoigne Wood conveyors on this day was well over 60,000 tonnes. This was pretty much a normal daily total for this period.
Total saleable coal leaving in the trains was 50,641 tonnes
1996 was the 5th successive year where annual saleable output exceeded 10 million tonnes. Profit for the complex in 1996 was reported to be £24.464 million.
Sadly the good times were coming to an end and production was to gradually fall away in the coming years as the better mining areas became worked out.
Report 1
Report 2 –Delay analysis for coal clearance systems 29.05.96
The two spine tunnels coming to the surface at Gascoigne Wood each contained a different type of conveyor.
The South Spine contained the ASL – named after Anderson Strathclyde Ltd, the designer and manufacturer. It was a 12.2 Km long steel cord conveyor running at high speed and capable of over 2000tph.
The North Spine contained the Cable Belt. The cable belt consisted of a very flat profile carrying surface resting on two steel cables. It was slightly earlier technology than the ASL and the flat profile gave rise to quite a lot of spillage, especially if one of the pulleys supporting the cables had a bearing failure, in which case the vibration caused the coal to be shaken off the conveyor. It normally ran at 1000tph but when demand for coal clearance was not so great, it was shut down and the ASL was used alone.
South Spine Delays
The first group of delays with the prefix ROM (Run of Mine) relate to stoppages of surface conveyors downstream of the ASL which in turn cause the stoppage of the main spine conveyors. CO7c was a common offender in this respect. It was the oversize conveyor feeding the barrel washer infeed stockpile and prone to large pieces of stone or timber causing misalignment or blocked chute.
Many of the other delays refer to belt torn protection being operated at various locations. B2 being Wistow bunker, B6 Stillingfleet Bunker etc. The belt torn probe was a wire stretched from side to side beneath the belt. If a piece of rubber was trailing from the belt then it would hit the wire and stop the conveyor. The conveyor was running at high speed so would take a little while to stop and the bunker operator would have some distance to walk to find the offending piece and cut it off.
Rollers were changed by a belt patrol team who did their inspection from a train travelling alongside the conveyor. The inspector was pretty much lying down in the vehicle so that he could see the underside of the conveyor.
Later in the evening problems start to occur with a steel cord coming out of the belt. This would need to have been chopped off and its position within the 24Km of belting noted for later vulcanized repair.
North Spine Delays
This conveyor was affected by the surface conveyor stoppages in the same way as the South.
The report shows several pulley changes and a rope off pulleys incident which were speedily dealt with. The numbers following the entry refer to the stand number on the conveyor structure. The last entry of “portal bubble trip” refers to a detector which was looking to ensure that the rubber belt was lying flat down on the cables. This consisted of a wire stretched at right angles above the carrying surface which would stop the conveyor if it was hit by anything. The trip wire had probably been hit by a large lump of coal on the conveyor and did not indicate a problem with the conveyor belting itself.
Report 2
Report 3 Gascoigne Wood Manager’s Morning Report
This is the summary of the day’s activities that landed on the Manager’s desk the following morning and a summary would be reported on to the Group Director.
The information in the first section predominantly comes from the Westerland feeders delivering onto the spine conveyors from each of the bunkers that the producing mines fed into. The feeders were wide slow flat conveyors of known bed depth and controllable speed which gave a pretty accurate record of tonnage throughput. Mounted over each feeder was a sensor picking up natural gamma radiation from the material passing beneath. Shale gives off more gamma than coal and so with careful calibration the percentage ash could be determined.
Coal from Whitemoor had to pass through Riccall Mine before it reached the spine conveyors and similarly North Selby coal had to pass through Stillingfleet. The ash monitors and weighers for these mines were located on the boundary between the mines and so were not under neutral control. This was often a source of much dispute between the mine managers, each seeking to gain maximum tons and hence income for their mine.
As a check on these ash measurements the GW Deputy Manager regularly visited the individual mines to do a rough face survey, measuring thickness of coal cut, amount of stone falling from the roof and thickness of floor dirt taken. This was a part of the job which I always found very interesting. These findings could then be used to adjust the ash content should it be necessary.
Belt weighers can vary greatly in accuracy so tonnage arriving at surface was adjusted to bring it in line with known weight dispatched over the certified weighers on the railway and changes in stock levels.
To reduce ash levels to those acceptable to the power stations a proportion of the coal needed to be washed and then re mixed back in. At this time there were two washing plants operating – The barrel washers which treated the larger material and the dense medium cyclone and spiral plant which treated the medium sizes. The undersize went straight through to form the basis of the blend. Tonnages into each process can be seen on the sheet.
The ash level to the power stations was running at 17.1% and we would be looking to bring this down a little by the quarter end. The customer paid on calorific value rather than per ton so a slightly high ash content would result in a lower return per ton. A factor critical to the customer was the handleability of the product. The last thing they wanted was coal sticking in the wagons and holding up the discharge of trains. Poor handleability was related to some extent by moisture content, which on this day was nicely in spec at 10.7, but could be more significantly affected by the MRF content.
MRF stands for Multi Roll Filtercake. This was produced by squeezing the moisture out of the finer material in the barrel washer plant. MRF had a good coal content but also contained fine clay particles which could cause handleability problems. It was obviously in everyone’s interest to send as little of this material to the tip as possible but blending it into the product had to be done cautiously to avoid sticky trains. A very fine balancing act.
A small amount of house coal was also being produced.
Three trains of stone left site to be disposed with domestic waste in Wakefield, the rest of the discard was disposed of in a very carefully constructed tip facility on site, with MRF cake enclosed in cells of coarser material. HAU stands for High Ash Undersize, of which 183,000 tons were on stock waiting to be blended back into the product when ash content from the mine reduced.
Report 3
Conclusion
This has been a very brief view of the activities taking place on this fairly typical day in 1996. The sheer size of the operation is clear to see with over 60,000 tonnes of mineral being brought to the surface and over 50,000 tonnes being dispatched to power stations throughout the country in a single day.
As with many mining projects, the geology of the area proved to be not as straightforward as anticipated in the early planning stages causing production to slow in later years. The basic design of the complex required high throughput to achieve cost efficiency and falling tonnages resulted in a rising cost per ton, leading to eventual closure in 2005.
Hopefully these reports give a glimpse of the coalfield operating at its designed output level, as it did throughout much of the 1990s, and give some indication of the tremendous engineering achievements and degree of human endeavour that made up this very bold project.
***
Again, many thanks to Neil Rowley who was Deputy Manager at Gascoigne Wood Mine and who provided the information and memories in this post.
The official opening of the Selby Coalfield took place on December 7th 1989. Queen Elizabeth and Prince Phillip were due to visit Riccall and visit H443s, a working coal face at the mine. On the day however, HRH The Queen was ill and HRH Prince Phillip attended alone.
The visit was seen as a recognition of all the hard work that went in to the whole project. His Royal Highness was introduced to British Coal Directors and the Mine Manager, the late Stuart Sumnall. He was shown into the concourse where he met with local school children and members of the mining staff. He was taken into the lamp room, had a tour of the surface, and then went underground. Afterwards there was hospitality and speeches with officials, miners and their families. A successful event, and a lasting memory and endorsement of the success of the mine.
The British Film Institute has kindly allowed me to show this video of the Royal Visit on my blog and I am sure many of you will be very interested to see this.
Many thanks to the British Film Institute for their kind permission to use this video and for their agreement for me to show this in four parts because of the upload limitations of this site.
Part 1
Part 2
Part 3
Part 4
Copyright BFI / Courtesy of the BFI National Archive
My memories of the day;
The face was prepared with cover plates fitted over the pan side cable and hose brackets, to ensure that no accidents happened during the visit.
A roof bolting demonstration was given by Dennis Nichols and an Anderson Strathclyde AM500 shearer demonstration was given by Terry Armitage and Phil Matthews. The deputy in charge of the district for the visit was Snowy Varley. During the visit, only a skeleton staff were allowed underground. I remember that three electricians, from our team, were at strategic points to ensure electrical problems were quickly dealt with, one being in the pit bottom substation, one at the main gate end substation and myself as the electrician in charge of the face.
I was waiting in the tailgate when I got a call to say that the face A.F.C. would not start. A very concerned and agitated undermanager appeared in the tailgate to ask me to go and see what was wrong. I quickly went to the maingate to see what the problem was. A power supply fuse had blown in the BFS switchgear supplying the panzer and it would not start. I replaced the fuse quickly and thankfully the A.F.C. started. The visit went ahead as planned with no further problems.
The event was recorded in a souvenir issue of the Coal News.
and we were all given a pit check along with a Royal Visit mug to commemorate the visit.
Many thanks to my mate Ian Cawthorne who kindly provided me with the digitised version of the original VHS video of the visit.
Ian worked at Riccall Mine as an underground fitter and chargehand.
The second of the two winders to be installed at Wistow Mine was a tower mounted, six rope, friction winder (Koepe). This winder was installed over the downcast shaft and had a single cage with counter balance weights. The cage was designed to carry 170 men on two decks or 16 tonnes of materials. To give some idea how large the cage at Wistow Mine was, a complete Dosco Dintheader heading machine could be loaded and transported underground on the cage.
They were the largest cages in the UK and weighed nearly 24.7 tonnes.
Below is the pictorial history of the installation and commissioning of the No1 winder.
The cage had to be manufactured and transported in two parts due to its sheer size.
The final pictures are the fitting and commissioning of the six ropes on to the 24.7 tonne cage and counterweight.
The cages on the friction winders in the Selby Coalfield were all tilting deck type. The middle section of the cage has central pivot points on both sides of the deck. Two hydraulic rams are mounted to the lower and middle deck and when operated the middle section is tilted and the load is held at an angle in the cage. This allows loads of up to 8.2 metres long. This system allowed the long, square section girder work, used in the underground bunker areas to be transported safely within the cage without the need to sling underneath the cage as used at many collieries.
Many thanks to Lisa Butterworth, Marketing Manager and George Wild, Company Secretary at Qualter, Hall and Co Limited for their time and for the use of the amazing photographs from their archive.
Selby Superpit 