| Abstract: | The blast furnace (BF) operation, as well as the steel‐shop downstream, can derive benefits from adjusting the slag alumina content with the proper addition of bauxite flux to its burden. Additions of 5‐15 kg of bauxite/t hot metal lead to a raise of the alumina content of the resultant BF‐slag from 10% to the level of about 12%. In Hellas extensive deposits of diasporic bauxite exist which, however, are under‐utilized by the alumina refineries due to their rather low solubility during the Bayer‐process. The above BF application, therefore, as an alternative use of the diasporic bauxite, is of great interest to the bauxite producers of Hellas. The influence of the bauxite additions on the metal/slag reactions under BF‐conditions was simulated in the laboratory by smelting BF‐slag with diasporic bauxite additions in a graphite crucible. It was achieved the production of BF‐slags with higher alumina contents under the condition of constant slag basicity. The results show the beneficial effect of the bauxite addition to the quality of the produced hot metal. In accordance to its desulphurization and desiliconization as well as the increase of BF‐slag sulphur capacity and fluidity, a thermodynamic evaluation of the metal/slag reaction in respect of SiO2 reduction and S‐transfer to the slag in relation to its Al2O3 content was carried out. This evaluation led to simple algebraic functions and graphs easily applicable by the BF operators. The attained metallurgical results were verified in comparison to industrial test heats with bauxite additions in the BF‐burden in USA, Canada and Europe. |
