Extractive Metallurgy Division - Preparation of High Purity ZrCl4 from Alkali Chlorozirconates

High purity ZrC14 (25 to 200 ppm of metallic impurities) can be readily prepared in simple apparatus by thermal decomposition of alkali chlorozirconate fused salts at 500° to 600°C and at atmospheric pressure. Suggested phase diagrams for the systems NaCI-ZrC14 and KCI-ZrCI, are presented. ALKALI chlorozirconate compositions — anhydrous fused mixtures of ZrCl4, NaC1, and KC1— are manufactured commercially and are used by the magnesium industry to introduce zirconium into magnesium alloys. Zirconium refines the grain size and improves the physical properties of many important magnesium alloys. In the course of working with chlorozirconate compositions of high ZrCl4 content, it was noticed that these salts decomposed progressively itwaswith increasing temperature to yield considerable amounts of a ZrCl4 sublimate of high purity together with a solid chlorozirconate residue. Further research led to: 1—improvements in the