Designing Stronger and Tougher MgO-C Bricks for Basic Oxygen Furnace (BOF)

摘要

Basic oxygen furnace (BOF) or LD converter is a relatively cheap process for refining iron into steel. However, the novel demands on low carbon metal production have been leading to: (I) the increase of the applied oxygen volume flow, and (II) the use of top and bottom blowing, in order to decrease operational costs via more efficient stirring of the molten steel in such equipment. Based on these aspects, MgO-C bricks (commonly used as refractory lining in BOF) have been continuously exposed to severe oxidation and corrosion by gases and slags, erosion due to molten metal turbulence and thermal shock stresses. Consequently, a new approach (based on mimic some biological and natural materials, i.e. nacre, sea-shells, human cortical bones, etc.) was used to design MgO-C refractories with improved strength and toughness. In this sense, a special phenolic resin binder was combined with nanographite particles or a special alumina in various proportions. Thermomechanical characterization of classic MgO-C bricks and bio-inspired compositions indicated that nanographite addition to the HTM (High Thermal Mechanical, which comprises phenolic resin and pitch in a particular ratio) binder was effective in increasing CCS and HMOR values of the refractories after curing (200 °C for 6 h) and firing (1400 °C for 5 h). Moreover, adding special alumina to such composition also increased its HMOR and thermal shock resistance, indicating that this might be a likely route to design damage tolerance materials.