Other interesting stuff – Page 2

Methane Drainage.

Throughout the history of mining, methane, which is a highly explosive gas with an explosive range of 5% to 15% in air has always been a major problem to the people working underground. Ventilation is the primary requirement for keeping the methane levels below the safe level of 1.25%. Thousands of explosions have occurred due to badly planned or insufficient ventilation in coal mines. When planning a mine, the fresh air drawn through the pit has to be of sufficient pressure and flow to remove the gases produced underground and keep them within set safe limits. There are many parts of a mine ventilation system used to achieve this including, the main fan, auxiliary fans, booster fans, air doors, regulators and air crossings to name a few.

When a coal face is mining, billions of cubic litres of methane are produced which has to be safely managed. The main way of achieving this is to supply vast quantities of fresh air at sufficient pressure and flow to deliver the quantity to dilute the methane passing through the face. The Selby Coalfield main fans were very powerful at 2,100kw and could draw upto 360 cubic metres of air per second around the mine to achieve the quantities needed.

A further control measure is to stop the methane getting into the air flow in the first place by drawing the gas from the strata above and below the working coal faces and sending it to the surface in pipes. This process is called Methane Drainage. The Barnsley seam worked in the Selby Coalfield is famously very gassy so Methane Drainage was planned during the design of the complex.

Riccall Mine used the same system of Methane Drainage during the life of the pit. The tailgate of every face had a system of boreholes drilled into the gob at a minimum distance of 10m at the back of the face line. This distance allowed for the strata in the gob to fracture and settle. If the holes were drilled too close to the faceline the standpipes were prone to being sheared when the gob settled. The system described below was used on all faces at Riccall Mine with the exception of East side of the pit.

Methane borers drilling top holes with mini Hydrac Drill Rig.

The top drainage holes were drilled at 60 degrees towards the gob every 15m in the tailgate roadway. The holes were bored using 18 x 2 feet 6 inch drill rods. The 18 x 2 feet 6 inch drainage standpipes were then installed into the hole with denso tape on each joint to seal the pipe into the hole. A stuffing box was then installed on the last pipe. The next stage was to drill a 50mm hole up through the standpipe with a further 42 x 2 feet 6 inch drill rods added onto the length of the hole giving an overall drilled length of 150 feet. This was called the production length and passed through the next 2 seams above the Barnsley seam called the Dull and Kents seams. The standpipe end was then connected to the methane drainage pipe range using a flexible 2 inch rubber hose. A hole was manually drilled into the methane range for a threaded connector piece for the pipe connection.

The methane borers had to work at the back of the faceline so ventilation was very important. The tail gate end of the face had steel reinforce supports called Fibcrete chocks installed as the face retreated. An anti static sheet, was fixed to the Fibcrete chocks, which regulated and directed the ventilation into the area at the back of the faceline where the borers were working.

The bottom holes were drilled at 60 degrees downwards towards the face every 40m in the tailgate roadway. The hole was drilled as above but only 8 x 2 feet 6 inch standpipes were installed with a stuffing box on the last pipe. The pipes on the down holes were sealed with oil well cement to ensure there was no water ingress from the lower strata. The 50mm diameter, production length was then drilled to an overall length of 150 feet passing through the Dunsil and Swallow Wood seams. The same process as above was used to connect to the pipe range. The methane drainage pipes were called pipe “A” and “B” and were 8 inch in diameter. Pipe range “A” was the ex compressed air range used for the heading development. Pipe “B” installed by the methane borers just before the face started production. Both pipes were laid in the rib side as the face retreated.

Hydrac Drill Rig and Power Pack.

The machine used to drill the drainage holes was called an E.D.E.C.O. Hydrac Drill Rig. Hydrac rigs were designed to have a drill stroke of 2 feet 6 inch to accept the drill rods of that size. A mini Hydrac rig was designed to have a drill stroke of 1 foot 3 inch for very confined spaces and heavily weighted roadways. The rig was supplied by hydraulic hoses from a pump which was situated slightly outbye of the faceline.

The transition from arch girders as primary supports to full roof bolting made a huge difference to working conditions for borers. The tail gate area became very confined and difficult for the lads doing the boring especially when working in the east of the pit due to the depth of the seam.

H472s tailgate using arch supports.

H475s tailgate with roofbolt supports.

Due to the difficulty and confined work and having to man handle the hydraulic rig, a specially designed hydraulic portable rig was designed for use in the Stanley Main seam in 2002. It was obviously called “The Moon Buggy”.

E.D.E.C.O. portable Hydrac rig (Bigbird’s Moonbuggy) used on SM 501s.

The 2×10 inch pipes with the trouser leg adaptor pipe at H504s Tail Gate end.

Due to the huge amount of methane produced at the east side of Riccall Mine the system was upgraded by using larger, 3 inch diameter standpipes, 65mm diameter borehole production length and 2 x 10 inch diameter methane ranges. The 14 inch pipe used in the return roadway was also upgraded to a GRP pipe.

At the outbye end of the tailgate, the two methane pipes were connected to the main methane range via a connector called a trouser leg. This pipe was 14 inch in diameter with methane monitoring sample tubes, pressure gauge, and manometer for testing purposes. The 14 inch methane range was installed in the return roadway and delivered the gas to the surface methane plant via No2 upcast shaft.

The surface methane plant contained four, Nash Vacuum pumps. The pumps operated automatically due to demand and were initially designed to vent the methane gas into the atmosphere.

In the early 1990s, the methane was used to generate electricity. The gas was sent to a separate filtration unit and gas turbine generator, manufactured by Dale Engineering.

Information kindly provided by my mate, Glenn Bryan ( Big Bird ) who worked as a Methane Borer on every face at Riccall Mine.

Routine Condition Monitoring.

When I started at Riccall Mine in 1986 the mine had a system of maintenance which was relatively new in the industry called the Routine Condition Monitoring or R.C.M. The team consisted of mechanical staff initially who carried out weekly monitoring of all equipment throughout the mine. Fans, machine gearboxes, motors, compressors, conveyor gear heads and rollers were all monitored. The system was based on testing an item of equipment, when brand new to set a baseline for the vibration profile for the item. The equipment was then analysed for vibration on a regular basis using a machine called a shock pulse monitor or S.P.M. Any irregular vibrations were picked up, investigated and monitored to ensure catastrophic failure didn’t occur during production. S.P.M. was the electronic device used in the development of this type of maintenance and it worked well in the early years of this technologies. The other major part of the system was gearbox oil debris analysis. Oil samples were taken on a regular basis from all gearcases. The oil was mixed with a solvent solution to remove the oil. The sample was then passed through a filter to gather any debris. The solvent was evaporated leaving a debris sample. This was analysed for types of metal particles or dirt. All the gathered information was inputted into the data monitoring system so that deterioration of internal bearings, rotating parts and oil deterioration due to ingress of dirt were picked up at an early stage.

As the system progressed extremely advanced, intrinsically safe, electronic equipment became available.This machine was called a Vibration Spectrum Analyser. At this point an electrical section of the R.C.M. department was created due to the extra workload.

All machinery had a list of specifications when manufactured. These included number and bearing types within the machine. All the specifications were inputted into the Spectrum Analyser software and all new machines such as fans, motors and gearboxes were tested for vibration oscillations and harmonics when brand new. This data was used as the baseline for future monitoring. Any faults in a machine were quickly found and investigated. This sophisticated system, along with oil debris analysis ensured almost no catastrophic failures of equipment and loss of production.

As automation progressed widely in the industry, all ventilation fans, compressors and conveyors were monitored constantly as part of the control and operating system, MINOS, to ensure safe operations.

Staffing the Selby Superpit

The Selby Complex of mines was a huge project involving many aspects. The individual mines were developed over a prolonged period of time and staff were required as the project progressed. Mining contracting companies were initially used for shaft sinking and development drivages with supervision provided by officials at the pit sites and management from the N.C.B. North Yorkshire Area Headquarters, based at Allerton Bywater. Deputies, for the shaft sinking, were the first staff to be transferred to the sites. As the Gascoigne Wood Spine Tunnels progressed and shafts were sunk at the five individual sites men were needed to staff the mines.

The N.C.B. needed to provide the staff, from existing collieries, to ensure the pits had experienced supervisors, miners, craftsmen and management to run the new mines. A phased closure of the older collieries in the North Yorkshire Area was planned alongside a recruitment plan of local people. These staff were called green labour with no experience of mining. The colleries to be closed were all from Wakefield, Leeds and the Castleford area initially.
Having worked at Riccall Mine and having one of the Deputies, on my shift, who supervised the shaft sinking contractors, I acquired some information about the shaft sinking supervisors deployed at Riccall Mine, who all transferred from Walton Colliery, in 1978 when sinking commenced.
The first men to be transferred were the Deputies / Shotfirers to supervise the contractors during the shaft sinking operations. These men were released from individual collieries before they closed and were experienced in shot firing, used during the sinking process.
The North Yorkshire Area colliery closure program started in 1979 and continued through the 1980s until all the staff were needed for full production to commence at the new Selby Complex. The list below is not exhaustive but contains the main pits used to staff all the Selby Mines with closure year.
Walton Colliery, 1979.
Peckfield Colliery, 1980.
Lofthouse Colliery, 1981.
Manor Colliery, 1981/82.
Park Hill Colliery, 1982/83.
Newmarket Colliery, 1983.
Rothwell Colliery, 1983.
Ackton Hall Colliery, 1985.
Saville Colliery, 1985.
Fryston Colliery, 1985.
Glasshoughton Colliery, 1986.
Ledston Luck Colliery, 1986.
Wheldale Colliery, 1987.
Nostell Colliery, 1987.
The collieries chosen to staff the Selby Superpit were very old collieries and were virtually worked out. The miners from these pits were often working with equipment from a previous era of thin seam mining so the transition to very heavy duty mining equipment was to be overcome.
A documentary called There’s Life North of Watford was made in 1982, two years before the Great Miners’ Strike in 1984 / 1985 and contains interviews with two miners and their wives talking about the difficulties of the transfer to the Selby Coalfield and living in the new area, in a village near to Selby.
The first mines to be staffed were Wistow Mine and Gascoigne Wood Drift Mine. Stillingfleet, Riccall and Whitemoor Mines were staffed in that order with North Selby Mine being the last to be staffed. In the early development of the complex and subsequent need for staff, entire groups of miners from closing collieries were transferred to the newly opened mines at Selby. Examples of this type of mass transfer were Lofthouse and Manor Colliery men went to Wistow Mine and Newmarket and Park Hill Colliery men went to Riccall Mine. When the men were transferred, transport was made available for the men by using coaches. Other men would use their own vehicles, often sharing the driving due to large amounts of overtime being worked. Some of the transferred miners moved to live nearer the new mines in the villages in and around Selby.

When collieries closed and staff were needed for staffing later in the development they were held on secondment at other collieries until positions became available at their chosen mine.
After the Great Miners Strike, collieries closed at a very fast pace. As places became available at Selby, miners transferred from the Barnsley area. The colliery closures progressed and miners from many parts of the country transferred to the Selby Mines. This resulted in a huge mix of men, from different areas as diverse as Scotland, North East, Wales and the Kent Coalfield, all working in the Selby Mines.
At Riccall the workforce changed from the late 1980s and men from Nostell, South Kirkby, Betteshanger, Askern, Sharlston and Prince of Wales all came to work at Riccall as the industry was decimated by the closures due to the government energy policies and the ‘Dash for Gas’.