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March, 1933

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When at Consett we are treading on ancient ground so far as the coal-mining industry is concerned, for Chopwell, now the largest colliery in the company’s group, was in active and prosperous production as long ago as Queen Elizabeth’s time. As this pit was then classed as a sea-coal mine, however, it was only natural that the heavy transport charges to the staiths on the river Tyne should greatly hamper development, and in 1611, in spite of an excellent seam of coal that existed at a depth of only seven fathoms, the property was adjudged to be practically valueless for this reason. This change in fortune was due to the improvements in mining technique which took place at that time and enabled the Wylam, Blaydon, Stella and other collieries on the banks of the Tyne to work the deeper seams and so placed them in a better position to compete with the shallower lying coal at the more remotely situated pits. Conseqnently, in 1635, whereas such pits as the Stella and Blaydon were each producing over 25,000 tons per annum and were now the largest in the country, Chopwell was not raising more than about 5,000 tons. It was not until fairly late in the next century that the wagon ways removed these transport difficulties, and by that time the deeper pits nearer the river dominated the position.

The Consett collieries had thus to await the development of iron smelting by means of coal before they achieved importance. In this neighbourhood an iron industry had been in existence from very early times, the local ironstone being smelted with timber fuel. In the time of William and Mary a company of German sword makers settled in the district, and the impetus given by their activities has been felt throughout the three intervening centries. When coal replaced wood fuel for smelting purposes the Towneley seam and its associated band of ironstone were vigorously exploited and formed the basis of the present industry. It was not until 1866, however, when the Consett Iron Company superseded the old Derwent Company, that the ironworks were established as one of the leading concerns in the country, so that the present great works represent the culminating point of the progressive policy which was originated in that year. In this expansion it is difficult to over-estimate the part played by the collieries, for not only is the coal very accessible — the lowermost seams outcrop — but it yields some of the best metallurgical coke in the country, as the following general analysis shows:–

	Per cent.
Fixed carbon	89.26
Volatile hydrocarbon	1.18
Sulphur	0.74
Ash	7.85
Moisture	1.71

All the coal produced is not, of course, absorbed by the steelworks and the major portion of the output is available for the open market, either in the raw state or as coke. For the disposal of these products the Company posesses excellent facilities. Coal or coke intended for export is shipped at the Company’s own staiths at Derwenthaugh, which are connected with various of the collieries by a private line, as shown in the large map. This map also shows the general dispositon of the pits and the interconnecting electrical power lines.

Normally the coal output amounts to about two and a-half million tons per annum and is raised from one of the most extensive royalties in the country, the total take exceeding 46 square miles. Not all of this is underlaid by coal, however, as the seam's outcrop above the lower reaches of the valleys and much of the property has been acquired for other purposes, viz., ganister and limestone quarries and for housing estates. Also the Company have persued a policy of buying land in preference to paying surface damage, which is generally considerable due to the shallowness of the seams and the earlier methods of working the upper beds. In the olden days as much coal was extracted as possbible without having to resort to artificial support, ribs of varying thickness being left in situ to keep up the roof. Portions of these workings are shown in Figs. 1 and 2, from which it will be obvious that very little further disturbance is necessary to ensure the collapse of the ribs, and this is what frequently happens when subsidence takes place from the lower seams now being worked. As a general rule about 40 per cent. of the coal was left in this way and in some cases it is proving practicable to rework these old areas. The pits from which the coal was originally won appear to have been sunk about 13 chains apart and when the workings had extended for about six chains from the shaft — around which much larger pillars are found — it was abandoned and a new one sunk. Much coal was also won from adits driven into the seams from the outcrops, and drainage was invariably secured by this means. Portions of the old drainage levels exist in the Hutton Seam to this day and afford remarkable evidence of skilled workmanship. They were driven in pairs to secure ventilation and their shape and sectional area have obviously been arranged to secure access with the least possible removal of coal, which is not surprising when the immense labour of winning them out with the inadequate tools then available is taken into consideration.

Present Methods of Working

The coal-winning methods of which we have been speaking form a strange contrast to those in use today, for the collieries were amongst the first in the country to adopt machine mining. Blackett conveyors were introduced at Langley Park Colliery as early as 1902. This innovation was due to Mr. F. O. Kirkup, now chief viewer of the Consett group, and represents a bold step when it is considered that such apparatus was entirely untried in those days. The tradition then started has been vigorously pursued and the collieries are now among the best equipped in the country in this respect. There are limits beyond which machine mining cannot profitably be applied, however, and the seams here do not lend themselves to mechanical undercutting, as they win readily by scalloping methods. Consequently, although mechanical methods are adopted wherever possible, few coal-cutters are in use on the longwall faces, but liberal use is made of them for heading work, and mechanical conveyors handle a large percentage of the total output, in spite of the fact that it is necessary to work certain of the workings by other methods.

Also, since the war, the number of ponies has been reduced from 1,000 to about 400, it being considered to be economic to instal a small haulage gear even if it dispenses with the services of only two ponies. These figures emphasise the importance that is attached to having the haulage arrangements with a sufficient surplus of capacity to render the whole system elastic, for it is realised that the success of mechanical methods depends very largely upon an ability to get the work out with a proper degree of continuity. Should, therefore, some interruption take place any accumulation of coal can be quickly levelled out and the sequence of operations at the face is not interfered with.

In the vicinity of the face the haulages consist of 15-, 25- or 35-H.P. units, which are operated on a system that is unique to these pits. The gears are of the endless type but are operated on the main-and-tail principle. A special type of fleeting wheel is provided to enable the rope to be driven in either direction, and the tubs are attached in sets as in the ordinary main-and-tail system. The ends of the rope are coupled together with a junction piece the same length as the set, and the trains of tubs are attached by Longbotham clips or other suitable attachment of varying strengths according to the duty. The system works perfectly, and has the advantages that single track only is necessary — a very desirable condition when working these seams — and the gears can be accommodated in small engine houses. Also, only two-thirds of the rope used with ordinary main-and-tail systems is required, and it is impossible to overrun the rope on dip gradients. These gears are made by the company themselves at their centralised engineering workshops at Bradley. A recent development of the equipment consists of a combined gear, provided with the two drums for normal main-and-tail operation, and with a fleeting wheel for operation, as just described. The fleeting wheel (Fig. 9) is in halves, and can be clamped on to the ordinary drum barrel of the gear, thus enabling the method of haulage to be changed over from one system to the other as circumstances demand. These haulages are simple to work and can easily be run by lads. The only difficulty arises when curves have to be negotiated on the crest of a hill, and in this case extra care must be paid to the correct radius of the curve so that the rope shall not foul the tub wheels. On ordinary curves, however, there is no tendency for the rope to catch, and bobbin sheaves are quite unnecessary. Nor is any difficulty experienced on curves on gradients so long as the gradient is uniform, or in one direction only.

The larger haulages are standardised as far as is practicable in order to keep spares down to reasonable limits. In all, eight different sizes are in use, and range in horsepower from 15 to 500, the following motor ratings having been adopted as standard:– l5, 25, 35, 75, 150, 225, 300 and 500 H.P. One of the 300-H.P. units, in this case operating a day drift at Woodside, Humber Hill, is illustrated in Fig. 4. The motor is a 625-volt, 360 r.p.m. machine, of Bruce Peebles manufacture, and operates a main-and-tail gear, supplied by Worth Mackenzie & Co. Ltd., of Stockton-on-Tees. A rope speed of 10 m.p.h. is attained. It will be seen that the first reduction is undertaken by a rope drive, this practice having been adopted in preference to the all-gear drive, since it relieves the motor of shocks and undue vibration. The motorman is housed in a separate compartment, and is thus able to carry out his duties without any danger from distraction; also, as electricity is used for heating, the arrangement enables a considerable economy to be effected in current. This haulage is, of course, situated at the surface.

A more or less typical underground haulage of the ordinary main-and-tail type is illustrated in Fig. 6, this being at work in the Busty seam at the Humber Hill drift.

The main engine-plane tracks are laid with 40-lb. rails laid on creosoted larch sleepers 3 ft. 6 in. by 6 in. by 3 in., accurate gauging being assured by two iron tie-pieces fitted to each pair of the 18-ft. rails. A view in the Woodside day drift showing the excellence of the track is given in Fig. 12, which also shows the system of steel arching in use. The arches, it will be seen, are carefully lagged and strutted and each member is secured to the next by three iron tie-pieces to prevent any possibility of displacement. The commonest size of section in use is 4½ in. by 3 in. and the usual size for engine-plane work is 6 ft. high by 7 ft. span. Great care is observed with the fishplates which are made as close fitting as possible. Furthermore rail skeatings are provided at both sides to safeguard the rope should the set jump the track for some reason or other. Needless to say, all these arches, rails, rollers, sheaves, &c., are the company's own products. The tail-rope sheave shown also calls for comment inasmuch as its construction is of the simplest, and it is unique in that the spindle runs in wooden bearings. This is likewise a product of the Bradley shops, and the bearings, which consist of well-seasoned oak derived from old tub frames, have proved to give exceptionally good service. They hold the lubricant better than a metal bearing, the pores of the wood affording a storage space for the oil which tends to ooze to the surface when any heating takes place. To assist in this process, before being put to use the bearing blocks are soaked for several weeks in oil and become thoroughly impregnated. Other advantages are cheapness, spindle wear is reduced to a minimum, and silent operation is secured under all conditions. A similar type of bearing is now used for the main-rope rollers and has proved much more satisfactory than the various other types which have been tried. In this case the bearing is accurately shaped to fit into the recess of a cast iron box frame and is secured in position by an iron strap. The same type of bearing is also used for larger wheels used to guide the ropes through an angle. A further improvement in the design of these wheels has been effected by casting a groove in the tread the exact diameter of the rope, thus enabling the connecting sockets to pass around without entailing any strain.

Conveyors

The early start made with mechanical conveyors has given the Consett staff an exceedingly wide experience with this type of equipment and the use of conveyors has now been reduced to a fine art. In this technique every endeavour has been made to carry standardisation to the utmost limits compatible with efficiency and adaptability. Consequently, with the exception of a few belt units which have been introduced to meet special conditions, all the conveyors are of one type — the Blackett — which has been found to give the most satisfactory, overall results in the particular conditions encountered in these pits. The standard length of face is 90 yards and it is very rarely indeed that any variation is made from this. Wherever possible the coal is won on the retreating system. To this end the system generally followed is to drive two sets of parallel winnings from 200 to 300 yards apart and connect them at intervals of 100 yards by driving a double stall, bordways course, 10 yards wide, to form the 90yard faces. The centre portion of the stall is packed, thus forming two roads, one serving as a back gate while the second accommodates a gate conveyor.

As generally arranged at present the coal from the retreating faces is handled by a gate conveyor 100 yards in length, and then delivered to tubs circulated by one of the small haulage units, but a troughed belt conveyor is in some cases laid along the entire length of the gate to deliver the coal direct to the winning road. Rubber belts have been found to work very well in these conditions, but it is considered that they are too liable to damage, as it is always possible that a pick or shovel may get jammed and inflict a serious injury on quite a new belt. To avoid this eventuality, and also in the interests of standardisation, experiments are now being made with a scraper type chain, made at the company's shops, which will work up to 250 yards. A chain of this type is illustrated in Fig. 10 which shows the tippler end of a gate conveyor, 210 yards in length, at work in the Woodside pit. A drawing of the links showing their method of construction is given in Fig. 15. The two face conveyors serving this mothergate unit are shown in Fig. 11. For the face units a 9-H.P. motor is provided, but for the mothergate conveyors a 15-H.P. motor is in service. The newer motors are totally enclosed in a steel plate casing and are fully flameproof in accordance with the Buxton certificate. Apart from the motors all the components of these conveyors — chains, pans, frames and gears — are made at the central workshops, of which more will be said later. In driving the winnings air drills are employed for the stonework and punchers for the coal. Following the tendency to adopt electrical power wherever possible, however, electrical heading machines are being introduced for the coal work and both Hardypick and Siskol electrical machines are now in operation.

In certain cases, where the conditions are suitable, the winnings are carried forward in conjunction with a longwall conveyor face, as shown in Fig. 14. This method obviates a good deal of dead work as the total coal is won at a profit and no capital is standing idle in the form of advance headings. As a rule the winnings are driven from 20 to 24 yards apart and the coal is left in to support the roadways, as shown in Fig. 13. The winnings may be goafed, however, and in this case the roads are supported by packs and steel arches.

Drawings and Photographs accompanying the article