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Colliery Engineering

February, 1955

At Horden Colliery

Incorporating centralised dust-collection into modern layouts such as that at Lynemouth may be said to be less difficult than attempting to bring about the same result in an older plant. That it can be done, however, is evident from consideration of what has been accomplished at Horden Colliery in the No. 3 Area of the Durham Division, National Coal Board. Sunk in 1903, this colliery for many years held the output record for Great Britain, and through its lengthy lifetime many improvements in mining engineering technique have been developed and perfected at Horden*. Due to the general situation underground, it must be some considerable time before any major reconstruction of the surface coal-handling plant between the cages and the washeries can be effected, but in an effort to increase the general efficiency of the present arrangements, several improvements of a less comprehensive nature are being made.

The problem of overcoming the dust nuisance in the tippler house is a case in point. The present output of 4,000 to 4,500 tons per day is drawn at the north and south shafts in 11 cwt. capacity tubs and is dealt with by six rotary tipplers and shaker screens,

In the early years dust at this point caused no concern, but with an increase in underground mechanisation and a necessity to work more friable seams the amount of dust raised impaired visibility to an unprecedented extent, Seeking means to combat this nuisance the Area Engineering Staff discussed the matter with various dust-prevention authorities and as a result a contract for a complete extraction plant was placed with Thermix industries Limited of London, S.W.1, this leading to a complete eradication of the nuisance,

Fig. 8 shows diagrammatically the layout of the plant which, through the kindness of Mr. R. McLaren, Area General Manager, we were recently able to visit with a view to collecting information for this article, Each of the six tipplers has been covered with a sheet metal canopy and from the top of each canopy there are two hoods which join an overhead trunk ducting running down the axis of the tippler house.

Beneath the tippler floor there is a second trunk ducting which is parallel to the first one and which accepts dust collected from six sets of chutes and shaker screens receiving from the tipplers. On the angle chutes below the tipplers the dust-collection hoods are fixed into a canopy enclosing the side of the chute, and on the hoods collecting from the screens are placed about 18 in. above the screen deck. In addition, on both No, 1 screen and No. 2 screen (which are reserved for gummings and the like) a dust-collection hood is fitted to the side of the vibrating frame and below the level of the deck, Connection between each of these hoods and the ducting is made by a length of flexible hose 6 in. in diameter.

Hand-operated dampers are built into the ducts at suitable points so that sections not required may be isolated at will, The cross-sectional area of both trunk ducts increases as they pass along the building and at the westerly end they conjoin to form a length of ducting of 3 ft. diameter. This in turn bifurcates to form twin manifolds leading into a Tubix multi-cyclone unit housed in a converted smalls bunker at the adjacent washery. This Tubix unit has four sets of tubes but instead of a total of 80 tubes as in the Lynemouth installation there are 180. A further slight difference is in the position of the cleaned-air outlet which at Horden is in the horizontal plane and which leads to a centrifugal fan driven by a G.E.C. motor controlled by Erskine Heap switchgear, the collector unit, fan, motor, and switchgear all being housed in the one room. The air passing through the fan contains only that very small proportion of the very finest dust that has not been taken out by the collector unit and so wear on the fan blades is infinitesimal; discharge from the fan is led to a vertical steel chimney 40 ft. high and such is the efficiency of the collector unit that even during the busiest period of the shift no haze is discernible at the chimney outlet.

Dust taken out of the collection unit falls into the hoppers below and is discharged by motor-driven Thermix airtight rotary valves to a closed Redler conveyor which, in turn, delivers the dust on to a filter cake conveyor from a nearby froth-flotation plant. This conveyor delivers both products on to a conveyor where they are mixed with the washed small to the coking plant. In addition, as the accompanying photographs show, the atmosphere in both the tippler house and the screen house has been improved out of all recognition, so much so that it has been possible to dispense with the payment of dust money to the tippler and screen-house attendants, The plant has now been in operation for about nine months and has proved very satisfactory.

* * See Colliery Engineering, page 76, April 1924.

Drawings and Photographs accompanying the article