Studies on the preparative and microstructural aspects of plasma-dissociated Indian zircon prepared in a specially designed plasma reactor (20 kW) are reported. The vital parameters involved in the process have been optimized for a high degree of dissociation with maximum feed rate. A near total phase separation (ZrO2 and SiO2) has been achieved in the plasma-dissociated zircon spheroids which constitute over 90% of the product. Microstructural studies have revealed that the spheroids are of two types with a distinct difference in the morphology of zirconia crystallites. Most of the spheroids have been found to have well-developed polygonal grains with spherulitic growth of ZrO2 in SiO2 glass. The rest of the spheroids consist of intergrown tabular crystals of monoclinic zirconia set in a matrix of silica. The silica present in the plasma-dissociated zircon has been amorphous and highly reactive, and is leached out using hot NaOH solution to recover fine grain zirconia.
Copyright:Copyright [1992]. All efforts have been made to respect the copyright to the best of our knowledge. Inadvertent omissions, if brought to our notice, stand for correction and withdrawal of document from this repository.