Abstract: A method for converting attapulgite clay which has never been heat treated sufficiently to destroy the natural colloidal properties of the clay to attrition resistant, low surface area, essentially catalytically inert particles adapted for use as a blending agent with particles of active zeolitic cracking catalyst. The clay, preferably mixed with an alkaline cementitious material (such as, for example, portland cement or sodium silicate) is sintered at a temperature above 1350.degree. F., preferably in the range of 1500.degree. F. to 1800.degree. F., to reduce surface area to a value below about 15 m.sup.2 /g, preferably below 5 m.sup.2 /g, and decrease apparent bulk density to a value below 1.1. The material is sized to form an essentially dustless, free flowing powder.

Abstract: An improved furnace construction is provided permitting ceramic materials of various types to be processed at significantly elevated temperatures or being transported to the furnace enclosure. More particularly, novel transport means are provided for said ceramic materials to avoid problems with thermal shock and chemical attack here and for encountered during such processing of the ceramic materials. The novel transport means includes a furnace tray construction for the ceramic materials exhibiting greater abrasion resistance at the elevated furnace operating temperatures and which preferably cooperates with a hearth member in said furnace construction having comparable abrasion resistance.