1. Production and composition of tars

1.1 High-temperature tars

At present, most tars are high-temperature tars obtained during the pyrolysis of coal to produce steelmaking coke for the production of cast iron in blast furnaces. This carbonization is carried out in coke ovens at a temperature of between 1,000 and 1,200 C and for a period of between 12 and 20 hours. One tonne of coal produces around 750 kg of steelmaking coke, 30 kg of tar, 11 kg of benzol, with the remainder consisting of gas (370 m ³ ), ammonia and water.

Western Europe currently produces around 2.2 million tonnes of tar in its iron and steel coking plants, and there is capacity to process 2.4 million tonnes.