10 02 01, 10 02 02, 10 09 03

Mean from 3 samples (Riley et al., 2020)

Slags are the major mineral by-product arising from the iron and steel industry, produced from the separation of liquid metal from impurities and spent flux.

Slags vary in composition depending on the production stage and processing conditions. Iron smelting results in either air-cooled blast furnace slag (ABS) or granulated blast slag (GBS and GGBS) depending on the manner in which the slag has been cooled.

In the UK, blast furnace slags derive from the integrated steelworks of British Steel in Scunthorpe and Tata Steel in Port Talbot, where typically around 300kg blast furnace slag is produced per tonne (Defra, 2017),

Air-cooled blast furnace slag has essentially the same basic chemical composition as GGBS, but on cooling develops into predominantly crystalline form, containing only 40-50% glass content (Tripathy et al., 2020) compared to the 90-100% of GGBS.

The predominant use of air-cooled blast furnace slag is as a construction aggregates, used in road construction.