Abstract

Introduction: The need to product high quality but low cost magnesite-carbon refractories materials, leads us to evaluate the importance of the raw materials’ choice for these products depending on the application in iron and steel industry. Despite the wide use of magnesia raw materials, there are no recent studies that critically analyze their actual performance related to their properties. In this work, a preliminary study was carried out to investigate the most used raw materials based on MgO in refractory field. Chemical and physical-mechanical analysis were performed on specimens integrally formed from each raw material. Three classes of magnesite have been analyzed: dead burned (DBM), “seawater” and electrofused magnesite. A comparison of the results was made and it has been defined in theory the ideal field of employment of these materials in steel industry. To verify the actual performance in real application, the bricks formulas most commonly used and marketed in steelworks were reproduced in laboratory introducing the raw materials with the best theoretical properties.

Material and Methods: Six different magnesia raw materials were analyzed preparing ten specimens for each of them. The main physical-mechanical features were evaluated performing tests such as apparent porosity, density, cold crushing strength, resistance to thermal shock, refractoriness-under-load, and thermal expansion. The chemical properties of the materials were evaluated performing test such as resistance to alkali corrosion and to slag attack, X-Ray Diffraction and Fluorescence. In the second part of this work the information acquired for each raw material were used to modify the formulation of magnesite-carbon products in order to improve their performance. The study was made on different magnesite-carbon brick used in the most critical places of the steel mill, in particular converter, electric arc furnace and steel ladle. In laboratory bricks with standard formula was made with the raw materials normally used in current industry’s application and it was compared with the bricks produced with the same formula but different magnesiti.

Results and Conclusions: The study of raw materials gave us interesting information in particular for dead burned and “seawater” magnesite. These materials show good properties of resistance to chemical and mechanical stress comparable in some cases to the performance guaranteed by the electrofused. At the same time, the results obtained for electrofused are useful to discriminate which magnesite use in relation to the application. The actual performance in real application of the bricks producing in laboratory was tested and the results obtained show interesting improvements. The formulation of new products appear to be attractive for a subsequent use at the industrial level.