Making bricks from slag

22/10/1898 – St Andrews Citizens – The utilisation of slag – A German brick making patent. An official German report, just published, contains particulars of a new process of making building bricks from furnace slag. Hitherto many attempts have been made to utilise the slag, but all have been more or less a failure, and the result has been that ironmasters have had to procure ground in the neighbourhood of their works, often at enormous cost, on which to store the useless material. In Middlesbrough brick-making from slag has been going on for many years, the brick being principally used for street-paving purposes, its permeability rendering it almost useless for building. The new process is said to overcome this difficulty. The slag is first broken up and then passed through water. This causes disintegration, the silica being separated in a soluble condition, and as such, hardens in the air and combines readily with caustic lime. The slag grains are next compressed with the silica, and by the addition of about 10 per cent, of burned or slaked lime, the subsequent hardening is facilitated, six or eight days being sufficient. The quality of the brick thus produced is said to be very much superior to the ordinary burned clay brick. The strength is seven times greater, and it has a much higher resistance to heat. Although it is five times as permeable as the ordinary burned brick, it does not absorb water so readily. In a test burned brick filled its pores with water in twelve hours, while a slag brick required 190 hours. The best kind of slag for the new brick is that produced in the making of forge, Thomas and Bessemer pig-iron, and of those kinds of slag, there are thousands of tons in the neighbourhood of all the Scottish ironworks, which can be had at present practically for the taking away. If the process is successful and there is good demand for the bricks, ironmasters might turn their attention to the new industry, but it would have practically no effect on the price of pig-iron.

1921 – 1941 – Numerous references of bricks being manufactured from slag by the Slag Brickmaking Plant, Shotts Ironworks

1940 – 1961 – Numerous references of bricks being manufactured from slag by David Colville and Sons, iron and steel makers, Motherwell, North Lanarkshire in partnership with Messrs. Clugston Cawood. Ltd.


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