Description of Clyde Iron Works

This description is from a leaflet for visitors to the works in the 1970's.

Clyde Iron Works, situated on the north bank of the river Clyde a few miles south east of Glasgow, dates back to 1786. During the Napoleonic Wars the famous short-barrelled naval guns known as 'carronades' were made there. In 1828 the works was the first to use the hot blast process invented by the Glasgow Engineer, James Beaumont Neilson.

Taken over by Colvilles in 1931, the plant has been completely modernised and integrated with the adjacent Clydebridge Steel works.

Raw Materials

The three raw materials used in ironmaking are iron ore, coal and limestone.

Ore Handling

The ore, which is approximately 50 to 60 % iron is imported from many parts of the world, including Sweden, Labrador, Venezuela, Sierra Leone and Newfoundland.

It is unloaded at a special discharge quay on the south bank of the Clyde and is brought to the works in trains of twenty-eight special bottom wagons each of thirty-five tons capacity. The ore is discharged into a trough and is then lifted by a 124 ton, 200 foot span orebridge crane and piled in a stockyard which has a capacity of 600,000 tons. From the stockyard ore is taken by conveyor belt to the screening plant, and after screening is taken by electrically powered transfer cars to bunkers. Pieces of less than half an inch in diameter go to the sinter plant whilst the larger fraction is conveyed directly to the furnace bunkers.

Limestone

This comes from Colvilles' own quarry at Shapfell in England. It is delivered to the works in railway wagons which are emptied into 35 ton capacity ore tipplers before being taken by conveyor and transfer car to the sinter plant and the blast furnace bins.

Coal

Coking coal is brought by rail in 20 ton wagons and is discharged at either of two side tipplers each of which has a capacity of 20 wagons per hour. From these the coal is fed into a 40 ton capacity hopper and is then taken by conveyor belt to one of the 26 blending bunkers; eight of these bunkers are of 350 ton capacity and 18 of 1,100 ton capacity. Revolving feed tables with adjustable ploughs then pass a measured quantity of coal from selected bunkers to a conveyor belt which passes under electro-magnets to remove tramp iron before the coal reaches one of the two Pennsylvania hammer mills which have a working capacity of 250 tons per hour. After crushing, between 80 and 85 per cent of the coal is less than 1/8 inch in size. The crushed coal is again taken by conveyor, this time to one of the two 3,500 ton capacity service bunkers above the coke oven batteries. From the service hunker a weighed amount is loaded into one of the two charging machines and is then fed, from above, into one of the 135 ovens. These ovens are of the Becker type and are in five batteries or groups. The average width of each oven is 16 inches, the height is 14 feet and the distance between door faces is 42 feet 14 inches.

Coke Ovens

The ovens are heated by either coke oven or blast furnace gas and at the end of the coking period (between 18 and 27 hours) the doors on the ends of the oven are removed and one of two pusher machines discharges the coke with a ram which extends the entire length of the oven; the pusher machine is also equipped with levelling apparatus and door operating gear. The door on the opposite (coke) side of the oven is removed by a coke guide. This is equipped with door turning gear and has a trestle work tunnel which funnels the coke from the oven.

During the coking operation the doors on both sides of the oven are sealed with clay.The coke is discharged at approximately 900oC and falls into one of two coke cars which are propelled by 80 hp electrically driven locomotives to the quencher tower where 3,000 gallons of water are sprayed on to it to extinguish any flames. The quenched coke is then discharged by pneumatically operated side doors on to one of two coke wharves. From these wharves, which are 160 feet long by 18 feet 6 inches wide, with a slope of 20 degrees, the coke is fed by hand operated gates on to a conveyor belt, and is screened for size; pieces over 1 1/4 inches go by conveyor to the blast furnace bins, and pieces of less than 3/8 inch go to the sinter bins: the remainder is sold.

During the coking process, gas is evolved in the ovens and is drawn via ascension pipes to the exhauster house, which has three BTH turbo driven exhausters each with a capacity of 940,000 cubic feet per hour. In the by-product plant the gas is cooled and the impurities are removed in this order:

Tar is removed in the electrostatic detarrers and in the tar decantation tanks, and is sold.
Ammonia is removed by passing the gas up a vertical column against a flow of water. The resultant 2 per cent ammonia solution is sold as fertiliser.
The benzole is removed by washing the gas with petroleum wash oil. Crude benzole is recovered in a continuous distillation plant and is then further distilled for the production of motor spirit etc, which is sold. The wash oil is purified in a Clayton cascade still.The cleaned gas is used in both Clyde Iron Works and Clydebridge Steel Works, and is also supplied to the Scottish Gas Board. The coke oven gas holder is of the Wiggins type and has a capacity of one million cubic feet.

Blast Furnace Plant

The raw materials for the furnaces are stored in thirty-two 350-ton capacity bins. Seven of these bins hold coke, seven hold sinter, six hold ore and the other twelve are used for sundries. The bins are below the 'high level', an elevated twin rail-track approximately 1,100 feet long, upon which four transfer cars run, and along which the coke and sinter belt conveyors are placed. The material is drawn off at the foot of the bins into electrically driven scale cars, one for each furnace; charges are weighed by a scale of 20,000 pounds capacity. The material is then discharged into skips, of which each furnace has two, operated by winches driven by 200 HP DC motors.

A large proportion of the furnace charge is sinter made in a Dwight-Lloyd plant which has a moving grate of 1152 square feet; 144 feet long and 8 feet wide. The sinter pallets are of SG cast iron and travel at a rate of up to 15 feet a minute. The raw material for sintering consists of iron ore dust and sinter fines with approximately 5 per cent coke dust and 12 per cent B.O.S. slag; this is mixed and fed to the pallets on top of a hearth layer of half-inch sinter returns. Oil is used for ignition, and a 300,000 cubic feet per minute fan, at 35 inches water gauge, draws air for combustion through the sinter bed. The mixture fuses into lumps and the combustion products are passed to atmosphere through a 270 foot chimney. At the discharge end of the plant the sinter is broken up in a disintegrator and then passes over screens to a rotary cooler 47 feet in diameter, equipped with a 200,000 cubic feet per minute cooling fan. It is then taken on a conveyor belt to the high level bins. The capacity of the sinter plant is 17,500 tons per week.

Furnaces

There are three furnaces at the works capable of producing more than 14,000 tons of pig iron per week. Nos I and 2 furnaces have a hearth diameter of 18 feet 3 inches and 10 tuyeres each; five Cowper stoves serve these furnaces whilst three serve the No 3 furnace, which is 22 feet 9 inches in diameter and has 12 tuyeres.

The stoves, filled with fire brick checkers, are heated by means of cleaned blast furnace gas. When the gas is turned off cold bast is blown through the hot brickwork and is heated to approximately 1,000oC before it enters the furnace; Nos 2 and 3 furnaces are equipped for high top pressure operation, i.e. the pressure inside the furnace is much greater than the atmospheric pressure. No 2 furnace was the first in Western Europe to be thus equipped. No 3 furnace has oil injection apparatus at each of the tuyeres. All three furnaces have steam injection into the blast.

Slag, which is lighter, floats on the molten iron inside the furnace and is run off from a slag notch situated some four feet higher in the side of the furnace than the iron taphole. The slag is run into open bowl ladles each holding approximately 20 tons. Iron is run from the furnace approximately once every four hours into brick lined, rail borne ladles each capable of holding up to 75 tons. It is then either converted still molten, in ladles to Clydebridge Steel Works where it is charged directly into steelmaking furnaces, or, alternatively, it. is taken to one of' the two pig casting machines where it is poured into moving double strands of moulds. The iron is cooled by water and the solid pigs, each weighing about 56 pounds, fall from the end of the machine into steel railway wagons. The pig casting machines have a capacity of approximately 120 tons per hour and are equipped with a winch of 60 tons capacity for tilting the ladle bowls.

Slag

The slag is treated in one of three ways.

Granulating

The molten slag is run from the furnace, at approximately 1,400 Deg C and is struck by a high pressure stream of water which 'freezes' it into small particles. The granules are sold as an ingredient for cement manufacture.

Foaming

The molten slag is poured from the ladle into a bed where it is quenched with water jets. The resulting product is crushed and then compression rnoulded into lightweight building blocks.

Air-Cooled Slag

Some slag is tipped out of the ladles and allowed to cool in air, after which it is crushed and screened. The material is then used for roadmaking, for railway ballast, or it can be treated in the work's new tarring plant to produce tarmac. Slag dust is used at the brickmaking plant where cement and colouring matter are added, and it is then pressed into bricks for the building industry. These attractive bricks can be seen in many large buildings in central Scotland

The Iron Making Process

Air is blown into the furnace, through the tuyeres, at approximately 1,000oC; in the heart of the furnace, directly opposite the tuyeres the temperature is approximately 1,900oC. As the hot gas travels up the stack it passes through the raw material fed from the top, and heats it. The carbon monoxide (CO) gas formed at tuyere level by oxygen from the air and carbon from the coke reacts with iron oxide in the ores forming metallic iron and CO2 gas. The gas leaves the top of the furnace at about 250oC and is led, via the downcomer, to a dust-catcher where owing to loss of velocity a great deal of the solid material drops and is caught in a hopper. The gas is then passed through a washing tower where some of the remaining dust is removed by an electrically driven Whessoe Zshocke disintegrator, which has a cleaning capacity of 3.5 million cubic feet per hour.

After passing through the spray separators, the gas contains only 0.005 grains of solid matter per cubic foot and is extensively used as a fuel for heating blast furnace stoves, coke ovens and boilers. Under normal conditions about 240 million cubic feet of blast furnace gas is produced every day. A Klonne gas holder of three million cubic feet capacity is used to assist in the distribution.

Dust trapped in the dustcatcher hopper is removed by a worm mechanism and is transported by railway wagons and conveyors to the sinter plant.

The water which cleans the gas in the washing tower is conveyed by launders to one of the two Dorr thickening ponds, each of which is 85 feet in diameter and 12 feet deep. In these, the solid matter is separated from the water, pumped to an agitator and filtered and dried before being returned to the sinter plant.

Power Station

The blast for the furnaces is provided by four turbo blowers, three of which are of Metro-Vickers design and have a capacity of 45,000 cubic feet air/Min at 25 pounds per square inch. The fourth is of CEC design and is of greater capacity. There is always a spare blower available in case of breakdown. Electricity for the works is generated at one or more of the three 5 megawatt UTH turbo alternators generating at 11kV, and there are two rotary convectors each of 650 kW capacity for DC supply. Two new boilers have been installed each with a steam capacity of 120,000 lbs/hr and one 10 megawatt turbo alternator. This additional plant will not only enable the Clyde Iron Works to meet all its electrical needs but will also enable it to supply power to the national grid.

Research Laboratory

Quality control of both raw materials and finished products is of vital importance to Clyde Iron Works, and well equipped laboratories are in use in both the coke oven and blast furnace departments. There is also a research laboratory which is responsible to the management for solving, in close collaboration with the plant personnel, the many scientific and technical problems which arise in the day to day working of the plant and no assist in the application of constantly improving techniques.

Welfare

The works has an excellent canteen where hot meals are provided. There is, too, a modern amenity block with showers, lockers, and cooking and messing facilities.
First aid is available in a well equipped ambulance room staffed by a trained nurse.