New Additive Packages for Self-flowing High-alumina and MgO Based Refractory Castables

摘要

Self-flowing refractory castables with special performance are continuously being developed. New and improved dispersant systems play an essential role in this development. The objective of this paper is to highlight the benefits of two novel admixture systems that have been tested in various refractory castables. SioxX/SioxX-Quick is a specialty additive package developed for use in microsilica containing alumina based castable systems. The main function of SioxX is to control flow properties whereas SioxX-Quick controls setting characteristics. In combination they will enable the castable producer to control flow and set time accurately. When SioxX replaces sodium hexametaphosphate, self-flow is improved by 20 to 30 % and shelf-life of dry premixes is significantly improved. SioxX-Mag is a new additive package being developed for basic refractory castables. It contributes to better workability and setting behavior of MgO based castables while hot-properties remain unchanged. High performance, cement-free MgO castables based on MgO-SiO2-H2O bond using SioxX-Mag as dispersant have been tested. Using SioxX-Mag together with microsilica, slaking caused by brucite formation is suppressed and crack-free dried samples are made. Another benefit of using this additive package is the improved drying characteristics allowing fast firing of the castable.