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Colliery Engineering

March, 1951

Underground stonework

Practically all the details of this ambitious scheme have been decided upon and the constructional work is well under way. Colliery personnel have completed an access drift from an upper seam to the new horizon and are now actively engaged on drivages for the new pit bottom. The access drift was taken 10 ft. wide by 7 ft. high on a dip gradient of 1 in 4 for nearly 300 yards. Drilling was by hand-held Holman compressed-air hammer drills and mainly to the pattern shown in Fig. 8. Experiments were made with various types of tipped drill, but eventually the most satisfactory performance was obtained from Z-shaped bits formed by the colliery blacksmith on ordinary drill steel. Each normal pull had 31 holes and these were fired simultaneously, using ½ sec. delay detonators to give five rounds.

For mucking, a Sullivan slusher was provided and this discharged on to a Meco 24 in.-wide troughed-belt conveyor. At the face of the drift there were two men per shift for three shifts per day. Payment was on a yardage basis and the overall average progress was 13 yards per week, increasing during the last six weeks to 18 yards per week. The maximum rate during any one week was 21 yards.

The drivage for the new pit bottom is being taken either way from the foot of the access drift. At each face there is a Joy hydro-drill jib rig similar to the one working at Ellington colliery. For muck loading in the north heading an 8BU Joy loader is used and in the south heading a Sullivan slusher. Each of these machines loads into skip type tipping tubs which are trammed to the foot of the access drift. There the tubs are tipped on to a Huwood PF scraper chain conveyor, parallel to the track, which delivers to a Meco 26-in. troughed conveyor belt installed in the access drift. From the delivery end of the belt conveyor the dirt is taken inbye in tubs. At present the road is being driven 12 ft. wide by 8 ft. high and will be enlarged to full section later. Temporary support is provided by 12-ft. straight girders set upon mild-steel pins inserted in holes drilled into the side. Delay-action detonators are used and a drill pattern of 34 shots per round is employed.

Work at the new horizon is being organised with a view to completing the circuit at No. 2 shaft first. When this is finished and No. 2 shaft fitted to raise the five-ton mine cars, the output from the upper level will be diverted by means of a spiral chute to the new level. This will leave the No. 1 shaft free for the deepening and refitting. As at present the connection with Woodhorn colliery will act as a second outlet.

For water storage at the shaft bottom the lodgement shown in Fig. 9 is planned. It will hold one million gallons of water and consists of roadways driven in the Five Quarter seam. The layout has taken advantage of the natural gradient of the seam to ensure that all water in the lodgement will be delivered to the pump foot valve, and for inspection purposes a drift will be driven above the lodgement to intersect the last gallery.

As underground connections with the existing neighbouring collieries are established, the ventilation circuit will be reorganised. Roads in the Main seam will be used as return airways and Ellington No. 3 pit and Newbiggin No. 2 pit will be used as upcasts for the colliery after being equipped with large axial-flow ventilators.

Surface proposals

The existing winder at No. 1 pit was described in the article on Linton colliery. Both Lynemouth winders are to be replaced by similar but larger Metrovick a.c. machines. Each motor will have a 1,225 h.p. rating and will run at 365 r.p.m. and work upon a 6,000 to 6,600 V., 3-phase, 50-cycle supply. The mechanical portion of the equipment is being manufactured by Robey & Co. Ltd., who are constructing bicylindro-conical drums of 12 ft. dia.

It will be possible to control each winder in three ways. Firstly, there will be local manual control in the winding engine house by means of a control and a brake lever in the usual manner. Secondly, the winder can be controlled manually from a position at bank by means of a control and brake lever operating through a remote-control servo mechanism. Thirdly, the winder can be started by means of pushbuttons from a position at bank, the speed during the winding cycle being controlled automatically by an electrical servo-mechanism. In all cases, electrical braking will be applied by the new Metrovick compensated system of dynamic braking.

Proposals have been approved for the reorganisation of both heapsteads to use the Lofco system of mine-car handling. Figs. 11 and 12 gives an impression of the proposed layout of No. 2 pit top. Details of the principle of the Lofco system of cage changing have been given in previous issues of this journal, and it will be remembered that its outstanding characteristic is the manner in which the travel of the cars is minimised. This feature is accomplished by the provision of two identical rotary tipplers, one on each side of the shaft, and within a few feet of the cage. From each cage the loaded cars brought by alternate winds are propelled to the same side of the shaft. After emptying, the car does not go through the tippler but is returned to the cage in time to discharge the next loaded car on to the opposite side of the shaft.

In some Lofco installations a traversing tippler is employed and the tippler is moved across the width of the heapstead for each wind. The tipplers being manufactured for Lynemouth will be 14 ft. dia., however, and so capable of accommodating two cars side by side, thereby eliminating traversing. As in other Lofco installations, the tipplers will be of the two-speed anti-breakage type. They will discharge through chutes and an apron feeder on to troughed rubber-belt conveyors. As No. 1 pit will be concerned solely with the handling of coal it will have only one belt conveyor, but the No. 2 pit will wind dirt as well as coal and two belt conveyors will be installed. Hinged deflection flaps fitted in the chute and controlled from a central cabin will direct the debris to the correct conveyor belt. For bringing materials an electric hoist will be fitted at No. 2 pit top; as this shaft will act as an upcast during the earlier stages, air-lock doors are to be provided. The doors will be of the guillotine type, operated by oil-hydraulics, and will be fitted along the shaft perimeter and controlled by the cage.

The proposed arrangement of the surface conveyors is shown in Fig. 13. The troughed rubber belt from No. 2 pit will deliver direct into a 200-ton capacity surge bunker which will receive, through a cross conveyor, from the No. 1 pit conveyor also. As mentioned earlier, coal from Ellington colliery is to be prepared at Lynemouth, and will be brought over the private railway line to be tipped, with other "foreign" coal, by double-ended tipplers into underground hoppers. From there, troughed rubber-belt conveyors will elevate the "foreign" coal into the surge bunker.

Two troughed rubber-belt conveyors will take the coal from the surge bunker into the coal-preparation building which is now under construction by the Mitchell Engineering Group Limited. Inside the washery building the coal feed will be screened at 1½ in. and the undersize taken by conveyor to the opposite end of the building where it will be treated in a Baum-type plant to the design of the Automatic Coal Cleaning Co. Ltd. The sizes between 8 in. and 1½ in. will be treated in a Ridley-Scholes heavy-medium washer designed to give a number of coal-cleaning circuits in parallel, so that the plant may easily be adjusted to deal with variations in the rate of feed. The Ridley-Scholes system is one of the more recently introduced processes and uses either milled scale or magnetite in a very shallow bath having a rubber-belt conveyor running along its base. Probably the most important advantages claimed for this design of washer relate to the low maintenance cost combined with accuracy of separation. Coal below 1 mm. will be treated in a Unifloc froth-flotation plant.

The coal-preparation plant will have a maximum capacity of 800 tons per hour and is believed to be the largest washery planned for the British Isles. The cleaned products from the three different preparation processes will be directed to sizing screens near the middle of the building and from there will be transported into wagons by rubber-belt conveyors fitted with anti-breakage booms. Rejects from the cleaning processes will be conveyed over the railway sidings to an overhead hopper from where they will be taken by diesel-engined dumper cars and disposed of in the sea.

As the wagons are loaded with cleaned coal they will be ticketed and then taken over the private rail link to Ashington colliery, where they will be weighed and assembled ready for despatch by British Railways.

Existing pithead baths at Lynemouth provide accommodation for 750 men and it is proposed that an additional building be erected. The N.C.B. Divisional Architectural Branch has completed the plans for this and other buildings, and the various units have been so placed that the circuit for workmen and officials travelling in either direction is straightforward and unlikely to cause congestion. The appearance of all new surface buildings have been the responsibility of the Divisional Architectural Branch and a surface layout aesthetically pleasing as well as utilitarian has been evolved.

At present there is an output at Lynemouth approaching 6,000 tons per week with an overall O.M.S. in the neighbourhood of 30 cwt., and it is hoped that the improvements mentioned will increase the daily output to 6,000 tons and the overall O.M.S. to 60 cwt.

Acknowledgments

For permission to publish this article we are indebted to Mr. D. Hindson, M.C., General Manager, No. 3 Area, Northern (N. & C.) Division, National Coal Board, who succeeded Mr. W. S. Charlton, M.Sc., who became Divisional Mining Engineer upon the formation of the new Division in January, 1950, and we gratefully acknowledge the help received from his staff — particularly Mr. J. Dawes, Area Chief Planning Engineer, and Mr. G. Robson, Senior Assistant Planning Engineer.

Drawings and Photographs accompanying the article