Dry pressed lightweight refractories from Virginia kyanite

Abstract

The utilization of the expansion accompanying kyanite’s inversion in the production of a dry pressed refractory insulating material has been studied quantitatively with respect to: (1) clay-kyanite-combustible ratio; (2) addition of fluxing and mineralizing materials; (3) variation in forming pressure; (4) variation in grain size of kyanite content; (5) effect of heat treatment; and (6) effect of forming characteristics on fire properties.

The resilient property of combustible-containing bodies has been controlled by small additions of bentonite or sodium aluminate. The disruption of the structure of the body during the kyanite’s inversion reaction has been controlled by small additions of Virginia apatite and sodium aluminate and proper heat treatment.

Indicative results show that it is possible to produce a dry pressed insulating refractory body from a 3:1:1 ratio of 35 mesh kyanite to clay to combustible which exhibits excellent dry properties, fired properties which comply with A S T W specifications of bulk density and volume stability, and cold crushing strength only slightly less than commercial grades of insulating refractories recommended for service at 2900-3000℉.