Aluminum Company of America

Thomas G Swansiger

Alan Pearson

Lawrence Keith Hudson

A composition and process for making an insulating refractory material. The composition includes calcined alumina powder, flash activated alumina powder, an organic polymeric binder and a liquid vehicle which is preferably water. Starch or modified starch may also be added. A preferred insulating refractory material made with the composition has a density of about 2.4-2.6 g/cm.sup.3 with reduced thermal conductivity, compared with tabular alumina. Of importance, the formulation has good abrasion resistance and crush strength during intermediate processing (commercial sintering) to attain full strength and refractoriness, good abrasion resistance and crush strength.

Composition and process for making an insulating refractory material

An improved process is provided for the recovery of sodium aluminate crystallized from a digest of caustic and lime with high-silica aluminous materials. The digest solution is concentrated by evaporation and then seeded with Na.sub.2 Al.sub.2 O.sub.4.2.5H.sub.2 O crystals to crystallize alumina from the solution as Na.sub.2 Al.sub.2 O.sub.4.2.5H.sub.2 O. The crystals are then separated from the mother liquor solution by filtration or centrifugation. The crystals are then washed with a solution having a lower caustic content than the mother liquor and an alumina concentration of about 50 grams per liter to remove any mother liquor remaining on the crystals. The sodium aluminate crystals are used as a feed for a subsequent Bayer processing step.

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Apollo, PA, United States of America

Thomas G Swansiger