Study of the Fitting Reaction of Zircon Sand with Sodium Hydroxide Using Differentiai Thermal
Hyung Sup Choi Director of Atomic Energy Research institute, Seoul, Korea; visiting Eldorado Metallurgical Laboratories, Ottawa, under a research grant from International Atomic Energy Agency. H. Cross Metallurgical laboratories, Eldorado Mining and Refining Ltd., Ottawa.
The caustic fritting reaction of zircon sand has been studied by X-ray and differential thermal analysis. The
sharp exothermic peak found at 550"C by differential thermal analysis corresponds roughly to the minimum temperature at which a fritting reaction between zircon and caustic soda is initiated. It is further observed that the optimum fritting temperature for the conversion of zircon sand is about 100"C higher than the initiation temperature for the reaction. Although the major constituents in the fritted product are considered to be sodium zirconate, sodium silicate and unreacted zircon, it is suggested by differential thermal analysis and X-ray results that the formation of sodium zirconium silicate possibly occurs simultaneously with the formation of the above constituents during fritting. In order to investigate the physical or chemical properties of the frit after water leaching, a differential thermal analysis and X-ray study of the washed product was made. The washed caustic frit of zircon sand is found to consist mainly of an amorphous hydrous oxide with a minor quantity of a poorly crystallized substance (unidentified). The above product, when heated, appears to undergo thermal decomposition, progressively exhibiting
dehydration in the temperature range of 140 to 300 c and rapid conversion to cubic Zr02 at 660"C.
Mots Clés:
analysis, Caustic, caustic soda, endothermic, fritting, sodium silicate, Zircon Sand Hyung, Conversion, Heating, Sand, sodium silicate, Temperature, Water, Waters, Zirconium
