Today, steel is most often produced by electric arc furnace process and through oxygen converters, where slag is one of the major byproduct. The slag is a formed during the melting of metals and because of its less dense than of molten metal, it floats on the surface and protects the molten metal from oxidation. An average of 100 kg of slags per ton of steel with a temperature of around 1650 ° C is generated, and considering that 1.500 million tons of steel is products annually in the world, today more and more ways of using heat from the slag are explored. In recent years, the slag was landed on the ground or pit where it was cooled and solidified without trying to reuse its heat. In this paper the process of steel production by electric arc furnace process and through oxygen converters, as well as possible heat recovery processes from the high temperature slag were described. To date, several different heat recovery method have been developed, which are divided into heat recovery processes by granulation and based on chemical phase transformations.