General
Blast furnace slag

For each tonne of cast iron, the quantity of slag produced depends mainly on the mass of non-reducible oxides fed into the furnace, and is therefore inversely proportional to the iron content of the iron ore. In the past, up to 1,300 kg of slag were produced per tonne of cast iron, using ores containing less than 30% iron. Conversely, some South American blast furnaces fed with ores containing more than 60% iron, and using charcoal with 3 or 4% ash as fuel, produce little more than 100 kg/t of cast iron (Tamet, Argentina, 1982). Rich ores (Dunkirk, Fos) usually produce 300 to 320 kg of slag per tonne of cast iron.