China's Refractories

Abstract: Magnesite fine powder, natural silica powder, light-burned magnesia fine powder, silica fume and middle grade magnesia fine powder were used as the starting materials, and silica sol as binder to get high purity lightweight spherical forsterite aggregates. The mixture was granulated on a disc pelletizer and then calcined at 1 400 ℃ for 3 h. The synthesized spherical forsterite aggregates were added in MgO based castables with MgO-SiO₂-H₂O binding system to replace equal-density high purity common forsterite aggregates. Effect of spherical forsterite aggregates addition on properties of MgO based castables was investigated. The results show that: compared with common aggregates, lightweight spherical forsterite aggregates can improve castables’ flow ability and decrease water addition; addition of spherical aggregates has little effect on cold strength of castables; with the increase of spherical aggregate addition, shrinkage of specimens after drying and heating at intermediate temperatures decreases, but the expansion of specimens after heating at high temperatures increases, bulk density decreases and apparent porosity increases, and thermal conductivity declines.

Key words: forsterite, lightweight spherical aggregate, magnesia based castable