Wollastonite-Based Structural and Heat-Insulating Materials for Nonferrous Metallurgy

Abstract

In this work, we consider the eventual replacement of asbestos as a component of heat-insulating and structural material (asbothermosilicate) used in the aluminum industry by noncarcinogenic concentrates of natural wollastonite currently available from domestic manufacturers. A technology has been developed in which the filler was natural wollastonite and the binder was an artificial finely disperse wollastonite synthesized using hydrothermal and sintering techniques. Wollastonite, like chrysotile-asbestos, is not readily wetted by molten aluminum. Its acicular crystals have a length-to-diameter ratio (L/D) that is smaller than those of asbestos. The binders for preparation of asbothermosilicate are diatomite and lime (cream of lime). The preforms molded by filter pressing are autoclaved and then heated at 600°C. Asbothermosilicate also contains partially dehydrated calcium hydrosilicates.