Crystallization and properties of high calcium glass-ceramics synthesized from ferromanganese slag

Ferromanganese slag (containing 41.7 wt% CaO and 4.5 wt% Al2O3) was used as main raw material to synthesize high calcium glass-ceramics. The amount of ferromanganese slag is 72.4-88.7 wt%. By adjusting Al2O3 content, the rapid crystallization problem in preparing high calcium glass-ceramics by using high content of ferromanganese slag was solved. Moreover, the effects of Al2O3 content on crystallization behavior, microstructure and sintering properties of high calcium glass-ceramics were investigated. The results showed that Al2O3 broadened the sintering temperature range of the powder and improved the uniformity of the grain distribution, achieving effective control of heat treatment process of high calcium glass-ceramics. With the increase of Al2O3 content, the crystallization activation energy increased from 199.7 to 236.9 kJ/mol, and the main crystalline phase changed from Ca2MgSi2O7 to Ca2Al(AlSiO7). When the Al2O3 content was at 11 wt%, the sample strength was 67 MPa and the water absorption rate was 1.8%.