High temperature gaseous corrosion resistance of MgO-containing refractories – A comparative study

In the work the results of investigations into corrosive resistance to the attack of sulphur oxides of six commercially available basic refractories containing magnesium oxide have been presented. The research was conducted for materials applied in glass furnace regenerators: three types of magnesia-zirconia-forsterite products, one magnesia-forsterite and one magnesia product as well as a magnesia-chromite product to be applied in copper convertors. Investigations were carried out in a semi-flow chemical reactor. Investigations into corrosive resistance were conducted at 600 °C, 800 °C and 1000 °C. The real and equilibrium composition of gaseous phase in the reactor versus temperature was determined. It was assumed that the relative increment of the tested products' mass after a certain time of their staying in the reactor would be and indicator of corrosive resistance. Based on investigations into the phase composition of the products of reaction, it was found that at 600 °C and 800 °C the product's corrosion resulted from the formation of MgSO4, as the main product of reaction, whereas at 1000 °C – it was the formation of CaMg2(SO4)3. In products with an addition of ZrO2 destabilisation of the regular structure of c-ZrO2 was observed as well as its change into the monoclinic variety - m-ZrO2. The examined refractory materials were ordered according to their corrosive resistance to sulphur oxides at particular temperatures applied in the test. The conducted investigations qualitatively describe the behaviour of refractories exposed to the corrosive attack of sulphur oxides and can be useful in the selection of refractory materials for particular industrial applications.