China's Refractories

Abstract: Chrome containing refractories are a kind of traditional material for the lining of alkali recovery furnaces, but the formation of hexavalent chrome compounds will give rise to detrimental effect on environment and human’s health. With the gradual awakening of people’s consciousness about environment protection, it is urgent to prepare environmental-friendly materials for alkali recovery furnaces with high quality and long life. In this paper, alumina-rich MgAl₂O₄ spinel (AR90) was used to replace chromite. The physical properties of dried (110 ℃ for 24 h) or fired (1 300 ℃ for 3 h) AR90 and chromite were studied, respectively. The alkali vapor method was used to determine the alkali resistance of the two materials. The results show that: (1) after drying at 110 ℃ for 24 h, AR90 specimens show higher apparent porosity and slightly lower bulk density than chromite specimens; after firing at 1 300 ℃ for 3 h, AR90 has significantly higher apparent porosity as well as higher bulk density; (2) after the alkali attack, the AR90 specimens sintered at 1 300 ℃ exhibit smaller strength change and much higher compressive strength than the chromite specimens; meanwhile, the permeability degree of alkali salt in chromite specimens is more serious than that in AR90 specimens, which indicates that AR90 possesses better alkali resistance.

Key words: alkali recovery furnace, chrome free, alumina-rich magnesium aluminate spinel, alkali resistance