1993 - Page 9
Cotgrave Closed After 32 Years
Also Cotgrave colliery (Nottinghamshire) sunk in 1959-1962 by the National Coal Board, was closed after 32 years when production ceased, also on 30th October 1992 but put on hold pending the investigations. However the colliery was abandoned at the end of March 1993. Production from the Blackshale seam, with 620 men, gave a total of 301,350 tonnes for the year.
Sinkers Came Mainly From Calverton
The sinkers came mainly from Calverton following the completion of work there. Site preparation had begun in 1954.
Shaft positions E465113 N336420, E465205 N336387, 40m above sea level.
Shaft sinking in 1956 revealed
- 4th Waterloo / 1st Ell, 4ft (1.2m) at 510 yards (466m)
- Roof Soft / Deep Soft 5ft (1.5m) at 590 yards (540m)
- Deep Hard 4ft 6in (1.37m) at 600 yards (549m)
- Parkgate up to 5ft 0in (1.5m) at 625 yards (572m)
- Tupton 3ft 1in (0.94m) at 640 yards (585m)
- Blackshale / Ashgate 5ft 3in (1.6m) at 683 yards (624m), sump 684.5 yards (625.9m).
A cactus grab was used to load the shaft debris into kibbles, following the explosives being detonated.
Town and Country Planning Consent
Town and Country Planning Consent was required for both surface and underground workings and in 1971 for work inside the shaft pillar.
The 2 shafts both 24 feet (7.3m) diameter, No1 being 729 yards (666m) deep with freezing process to 126 yards (115m) and No2 was 626 yards (572m) deep. Both shafts were initially lined with reinforced concrete to 275m and mass concrete to 625m. In spite of precautions taken during the construction of the shafts whilst sinking, parts of the concrete lining were attacked by the sulphates present in the strata and cast iron tubbing had to be installed through the water-bearing measures and additional reinforced concrete reducing the diameter of both shafts to 22’ 6” (6.86m).
The twin-towered headgears at 47 yards (43m) housed the 1,800 hp Koepe multi-rope winding engines with 15 ton skips at No1 shaft. This tower housed 2 independently engines each powered by a 1,345 Kw electric motor giving 37 winds per hour, about 560 tonnes, each one operating a skip and a counter weight independently. The winding could be done either manually or automatically. Materials or 2 mine cars and manriding with 40 men x 2 decks at No2 shaft with a maximum winding speed of 11.3m per second.
Permanent headgears were completed 1958/59 as well as a fan drift at No1 UC shaft. Emergency shaft lighting by batteries was installed in 1958. Temporary pithead baths were erected in 1958 and permanent ones in 1960. Lord Robens Chairman of NCB visited the mine in 1961. The official inauguration was by Princess Margaret. The colliery was first approved in 1954 with Stage II approval 1957 and it was over 9 years to first production. However the colliery never lived up to expectations and overall lost money. A new village was built with all recreational facilities to house the workforce with many men coming from the closed pits in the North East.
Correlation of the workings were carried out in 1961 by Weisbach triangles at No2 shaft and in 1964 by single wire in No1 shaft and 2 wires in No2 shaft to fix to NMG (National Metric Grid) for first time and in 1972 using wires and check using a Gyro-theodolite and agreed on an existing underground base to 40 seconds of arc with the pit bottom position using a Wild Auto-plummet at No2 shaft and a further check bearing on inbye bases in 1991 using the Gyro theodolite. A check levelling of the shaft depth agreed to 8” (0.201m) at No1 shaft in 1976 and No2 in 1977 using (electronic) EDM instrument. An unusual method of identifying theodolite stations underground was by each successive number starting at No1 and continuing as No 301, No 580 and No 1052 for example.
Underground locos: 2’ 6” gauge
- 2 x 4wDMF 48DLZ 1961, 0-6-0 DMF 100hp HC 1963
- 2 x 0-6-0 DMF 100hp HC 1964
- 2 x 4wDHF 28hp HE 1973
- 4WDHF 28hp HE 1979.
Seams worked: Headings from shaft 1958 at 30’ 0” (9.1m) above Deep Soft. Production started with the Deep Soft Jan 1964-26/1/1979 (excessive floor lift, causing the seam to be abandoned) and continued with a pit bottom in Deep Hard. This seam was worked Jan 1968-1990 and trials in the Parkgate -7/5/1977. Blackshale abandoned 16th October 1992.
All The Coal Went To The CEGB Ratcliffe On Soar Power Station
All the coal went to the CEGB Ratcliffe on Soar Power Station with trains shuttling back and forth, it being the first pit sunk south of the River Trent. Geological problems were experienced in 1988 and by Feb 1989 the pit had lost 11m in 9 months and it was proposed that 500 jobs had to go. First 1million tons in 1968/69, with a total of 1,037,552 tons, produced by 1,316 men. Maximum output 1,056,788 tons and maximum manpower 1,808 in 1977/78.
Modern systems of work were introduced and in 1986 there was 6 faces working, 5 in Deep Hard and one in Blackshale on 15 machine shifts. However the loader gates lips were bored and fired and the gateside packs put on by hand! Chainless SERDS power loaders were in use and the stables eliminated by the shearers. A nucleonic sensor to keep the machine drum from cutting into the roof above the seam is shown in the photograph.
Heavy duty self advancing hydraulic powered supports were introduced and monolithic packing as an experiment. Dosco road headers were used for roadway development. Coal was transported from the faces by 900mm gate conveyors onto 1050mm trunk conveyors to a 200 tonnes horizontal bunker directly feeding the skip pockets. Several inbye horizontal bunkers and a 1,000 tonnes capacity vertical bunker controlled the flow of the run of mine. Large battery-operated locos were used for manriding and supplies haulage. One panel in Deep Hard approached within the curtilage of Tollerton airfield and close watch was kept for signs of subsidence that could affect air transport.
Roof bolting for Deep Hard H65s face salvage and gates was done just prior to closure.
At the surface the run of mine was fed into a 750 tonnes bunker and regulated to the coal prep plant at 550 tonnes per hour. Dirt disposal was by TS14 20 tonnes capacity motorised scrapers to 2 sites and a conveyor delivered dirt to a third site. Slurry lagoons were constructed. Out of the total 199 hectares available for tipping some 42 hectares was let to local farmers and 26 hectares of land had been restored to farm land by 1986. The system was ongoing even after the pit had closed.
Cotgrave was an isolated pit not connected to any other and 560m away to the west at the closest point from abandoned workings at Clifton. Around 3 gallons per minute of nuisance water was pumped to the surface, static head 573m from below Deep Hard and discharged into the defunct Grantham Canal.
5 panels in Deep Soft:
- 53s - Jan 1964 working South East - Mar 1966
- 4s - Aug 1964 South East - Nov 1967
- 3s - Nov 1964 North West - Dec 1965
- 5s - Apr 1965 South East - Aug 1966
- 2s - June 1965 North West - Jan 1968. Excessive floor lift caused the seam to be abandoned.