Effect of reclaimed bauxite on andalusite-based refractory castables for tundish applications

Abstract

The robust nature of alumina refractory materials presents opportunities for their in-process reclaiming and re-use in non-critical applications. Virgin refractories can be substituted with different quantities of reclaimed materials without compromising the quality of the refractory products. In this study, the effect of reclaimed bauxite on andalusite-containing refractory castables for tundish applications was investigated. The recycled bauxite was formulated in different proportions to replace virgin andalusite in the castables. Standard tests were conducted to evaluate the physical, physicochemical, and thermochemical properties of the formulated products. Static corrosion tests were conducted using tundish slag in order to simulate the actual operating conditions. The results show that the standard flow behaviour, open porosity, and bulk density of samples containing up to 22 mass% reclaimed bauxite were comparable to those of the reference castable. However, high-temperature properties such as static corrosion at 1400°C and hot modulus of rupture at 1500°C indicated that there is an upper constraint to the amount of substitution. The study demonstrated direct potential savings of up to 10% when the reclaimed alumina replacement ratio was increased to 22 mass%.

A low bulk density, low thermal conductivity permanent lining castable for tundish obtained by adding pearlescent sand

“…In general, the tundish permanent lining castables are mainly aluminum-silicon castables, which have excellent hightemperature physical and chemical properties such as high refractoriness, high strength, and good thermal shock performance. 13,14 Some researchers have tried to introduce high-strength lightweight aggregates into traditional castables to realize the lightweight of traditional castables. [15][16][17] Combining the advantages of low bulk density and good thermal insulation of alumina hollow spheres with the characteristics of high refractoriness and good thermal shock of mullite, Wang et al introduced alumina hollow spheres into mullite castables and developed a lightweight castable with excellent high temperature resistance and thermal insulation.…”

“…The bulk density and thermal conductivity of the castables prepared with these lightweight aggregates are extremely low, but their key properties such as strength and thermal shock are still insufficient to meet the requirements of tundish permanent linings, and the prices of high‐strength lightweight aggregates are much higher than that of traditional aggregates. In general, the tundish permanent lining castables are mainly aluminum‐silicon castables, which have excellent high‐temperature physical and chemical properties such as high refractoriness, high strength, and good thermal shock performance 13,14 . Some researchers have tried to introduce high‐strength lightweight aggregates into traditional castables to realize the lightweight of traditional castables 15–17 .…”