Heat recovery from steel slags

Danas se čelik najčešće dobiva elektrolučnim postupkom i putem kisikovih konvertera gdje kao nusproizvod nastaje troska. Troska nastaje tijekom taljenja metala te zbog manje gustoće od rastaljenog metala, pliva na površini te zaštićuje rastaljeni metal od oksidacije. Prosječno po toni čelika nastaje 100 kg troske s temperaturom od oko 1650 °C te uzevši u obzir da se godišnje proizvodi 1.500 milijuna tona čelika u svijetu danas se sve više istražuju načini iskorištenja topline troske. Prijašnjih godina, troska se odlagala na tlo ili jame gdje se hladila i skrućivala bez pokušaja da se iskoristi njezina toplina. U ovom radu opisan je proces proizvodnje čelika elekrolučnim postupkom i putem kisikovih konvertera te je dan pregled mogućih postupaka oporabe topline od nastale troske. Do današnjeg dana razvijeno je nekoliko različitih tipova uređaja za iskorištavanje topline koji se temelje na oporabi topline granuliranjem te kemijsko faznim promjenama.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