EFFECTS OF COMPOSITION AND GRANULOMETRY ON THERMAL CONDUCTIVITY OFrnANODE COVER MATERIALS

摘要

Thermal conductivity of anode cover material is critical inrndetermining cell top heat loss. It has been observed that thermalrnconductivity of cover material is strongly dependent on packingrnand particle size distribution. Granular material that is denselyrnpacked (lower voidage) has higher thermal conductivity. Whenrntwo sizes of spherical particles are mixed at various size ratios, therntheoretical voidage can be reduced from 0.4 to 0.2-0.3. This canrnbe applied to a particle system of crushed bath and alumina thatrnconstitute cover material. Currently, many smelters producerncover material that is too fine with high voidages. This has therneffect of lowering the thermal conductivity which can causernunnecessary operational problems within the cell. Additionally,rnthe effect of cover composition on thermal conductivity is notrnobvious. This paper describes studies conducted in the laboratoryrnto understand the effects of composition and voidage on thermalrnconductivity of cover material.