Mine & Quarry Engineering

December, 1936

The limestone quarries

As an ancillary activity to the production of steel, the company operates limestone quarries at Rowrah, some ten miles from Beckermet, capable of producing an output of 3,000 tons per week. At present the face is in a state of transition, work being in progress to unite what are practically two separate quarries into one. Fig. 8 shows part of what will ultimately be a continuous face 500 ft. long and having a height ranging from 40 ft. to 100 ft. The holes arc bored by a well-hole boring rig (Fig. 8) supplied by the Emsco Engineering Co. Ltd., driven by a 4-cylinder "Buda" petrol engine. This equipment operates on a bench 20 to 25 ft. wide and sinks holes 6 in. in diameter down to the quarry floor — a depth of about 70 ft. The holes are spaced at intervals of about 12 to 14 ft. and set as near to the back of the bench as possible. They are charged with Gelamex No. 1 and Gelamex No. 2 in 9 lb. cartridges having a diameter of 5 in. Simultaneous firing is obtained by connecting all the charges together with "Cordtex" instantaneous fuse which is ignited by a single detonator from a length of "Cordeau" slow-burning fuse. Other drilling machinery consists of Ingersoll-Rand jackhammers, drilling holes from 2¾ in. to 1¾ in. to depths of 20 ft. or more, and smaller jackhammers for breaking down large lumps and trimming the face. The bench holes are spaced 10 ft. apart, 10 ft. back from the face and are bored with round, hollow steels, 1¼ in. diameter, having a double chisel bit. They are charged with Blasting Abelite, whilst for the pop holes Gelignite is used. The broken rock is loaded into 4-ton side tipping wagons by a RustonBucyrus shovel of 1½ cu. yd. capacity and a Ransomes & Rapier unit of 7/8 cu. yd. capacity, the former being used for quarrying while the smaller machine is used for ridding. Fig. 9 also shows a portion of the quarry face that is being cleared back as part of the opening-out operations. In this case the face is worked sheer, being only 50 ft. high.

Power for the drills is supplied by an 80 h.p. Ingersoll-Rand steam-driven compressor delivering 500 cu. ft. against a pressure of 80 lb. per sq. in. A view of the crushing and screening plant is shown in Fig. 7. This is driven by a 60 h.p. Ruston & Hornsby steam engine and comprises two "Knapping-Motion" crushers (W. H. Baxter Limited) reducing down to 4 in. cubes ; the larger machine, 36 in. by 20 in., has a capacity of 60 tons per hour, and the smaller, 24 in. by 15 in., a capacity of 30 tons per hour. Sizing is effected by a two-deck vibratory screen, also by W. H. Baxter Limited, having the upper plate punched with 1 13/16 in. holes while the lower deck may be provided with a 5/8 in., ¾ in., or 7/8 in. wire mesh as required. To deliver the stone into the wagons, a 3 ft. wide plate belt conveyor is in service, supplied by Mitchell Engineering Limited. A further conveyor, in this case an 18 in. rubber belt conveyor made by Fraser & Chalmers, is provided to deal with the refuse. It is separately driven by a 5 h.p. steam engine.

The quarry is necessarily worked to the dip and is dewatered by two "Cameron" double-acting pumps having a total capacity of 8,700 g.p.h. It is also necessary for the same reason to haul all the stone up a gantry, 130 yards in length and having an average gradient of 1 in 4, to the crusher level. For this purpose a 60 h.p. twin-cylinder steam engine has been installed.

Floodlighting and other illumination about the quarry plant is provided by a 550 r.p.m. 230 V Petter paraffin set of 5 kW capacity.

In concluding this brief account we have pleasure in acknowledging the courtesy of the Workington Iron & Steel Co. Ltd., for granting us permission to inspect the properties, and we should also like to put on record our appreciation of the kindness extended to us by Mr. W. Sherwen, General Manager of the Iron Ore Mines and Quarries, and Mr. R. Neill, his assistant, on the occasion of our visit.

Drawings and Photographs accompanying the article