Energy considerations of classical and new iron- and steel-making technology

Energy consumption can be decreased in classical iron- and steel-making processes mainly by using heat in waste gases and in hot sinter, coke, slag, steel, and cooling water. A total consumption of 4000 Mcal/tonne (17 GJt) of steel can realistically be aimed for, i.e. 20–50% less than present levels. Iron making consumes 70% of the total energy and here new smelting reduction methods, originating from the blast furnace or basic oxygen converter, are being developed. The new methods use different energy sources and are flexible. Direct casting close to final size could also save a lot of energy. Not long ago it was generally believed that an increased technical and material standard inevitably meant increased energy consumption. To be optimistic required believing that energy consumption should increase. Nowadays progressive people strive for lowered energy consumption, total as well as specific (see Ref. 1). The iron and steel industry in Sweden takes 20% of total industrial energy and is energy intensive, as shown by its annual energy use of 500 MWhr(1.8 × 1012 J) per employee, 10 times the energy use per employee of the heavy machinery and construction industries. It is therefore understandable that energy questions will always be important in the iron and steel industry.