Progress in the utilisation of steel slags in the UK: Fid-Bau Portal

Progress in the utilisation of steel slags in the UK

Thomas, G.H.

There is a long history of successful utilisation of basic oxygen slags in the United Kingdom. First basic open hearth slags and later electric arc furnace slags have found useful application in coated wearing coarse products. Efforts at commercial utilisation were especially successful in South Yorkshire, where the slags had particularly low free CaO contents. When basic oxygen steelmaking (BOS) slags became available, their utilisation presented a challenge due to their significantly higher free CaO contents. The South Yorkshire slags were employed as a reference against which the performance of the BOS slags could be assessed. Research into the behaviour of basic steel slags quickly established that free CaO levels were not a reliable indication of volumetric stability. The concept of selecting slags on the basis of an accelerated expansion test was never seriously considered. Clearly the process would leave a proportion of the slag output unmarketable. Intensive research was carried out to establish effective 'weathering' regimes, capable of producing a volumetrically stable product. After satisfactory weathering, residual free CaO levels were shown to vary over a narrower, but still fairly wide range. The success of these procedures was demonstrated in a series of road trials; initially within the steelworks but later in public roads. During these trials, the value of basic steelwork slags as a surfacing material was clearly demonstrated. Of particular benefit is the inherent property of maintaining skid resistance characteristics. As a result of the research, high quality surfacing material with excellent physical properties has been used successfully for a number of years. Progress has also been towards the use of BOS slags in other sections of the road. (VDEh)