What is the UK meaning of slag


slag, 1) geology: pyroclastic fragment consisting of more or less vesicular, SiO2- poor lava is built up and is mainly formed by strombolian eruptions (volcanism). 2) technology: generally molten residues from melting operations. In connection with pollutants, this can be blast furnace slag, steelworks slag, power plant slag (melting chamber granulate) or non-ferrous metal slag. Grate ashes from waste incineration plants and residues from hazardous waste treatment plants (rotary kilns, fluidized bed furnaces) are also referred to as slag. Due to their mechanical and chemical properties, slag is recycled wherever possible. The slag produced during metal production or processing can contain heavy metals and cyanides. Power plant slag contains more or less heavy metals depending on the raw material burned. Both power plant and blast furnace slag are largely inert, i.e. the pollutants they contain are usually no longer mobile due to the vitreous structure of the granulate and cannot react with the surrounding material. To check the leaching behavior, the material to be recycled is subjected to an eluate analysis. Power plant and blast furnace slag are mainly used in road construction and the building materials industry (blast furnace cement, slag, slag).

Slag from waste incineration plants contains approx. 10% scrap iron, which is removed electromagnetically and recycled in blast furnaces. The remaining slag must be cleaned of soluble salts, some of which contain heavy metals. The fine grain fraction, which is more susceptible to leaching of pollutants, is often removed. The remaining coarse-grained slag can be used in road construction, for example. The slag produced during the treatment of hazardous waste has a different composition depending on the origin of the hazardous waste. They are also subjected to an eluate analysis. They are only used when completely inert, otherwise they are disposed of above or below ground. In some cases, special mono landfills are operated for slag. The slag found in old deposits is often a particular problem. They often have high levels of PAHs and heavy metals.