Increasing the crystal size of periclase in magnesia can reduce the reactivity of magnesium oxide with carbon slag, which is beneficial to improve the slag resistance service life of refractories. Magnesium-calcium synthetic sand In recent years, large crystalline magnesia has attracted more more attention. Figure 1 shows the resin-bonded asphalt-bonded MgO-C bricks produced sintered magnesia used for the trunnion upper cone of the alkaline oxygen converter The relationship between the crystal size of periclase the erosion rate when it is used. It clearly shows that the use of large crystalline magnesia can reduce the erosion rate of MgO-C bricks by one third.
The crystal size of periclase in the sintered magnesia produced in the past is only 4060μm, so the magnesia used for MgO-C bricks requires the crystal size of periclase to be greater than 80μm. Due to technological progress, large crystalline magnesia of 100160μm can be produced, the average crystal size is developing towards 200μm. Therefore, large crystalline magnesia should refer to magnesia with periclase crystal size greater than 100120μm.
In the production of sintered magnesia, controlling the chemical composition, increasing the forming pressure of the billet, increasing the sintering temperature extending the holding time can increase the crystal size of periclase. Using oxygen-enriched blast combustion in the shaft kiln to reach 2200°C, large crystalline magnesia with a crystal size of 130200μm can be produced, while traditional magnesite periclase crystals do exceed 100μm. The effect of high-temperature calcination is obvious, but it consumes more fuel. Adding a small amount of Zr2O can also increase the size of periclase 5080μm to more than 100μm, see Table 1. A small amount of SiO2 TiO2 can also increase the crystal size of periclase.