original_query: What is one method for obtaining pure yttrium from mixed oxide ores?
query: What is one method for obtaining pure yttrium from mixed oxide ores?
answer: One method involves dissolving the oxide in sulfuric acid, fractionating it by ion exchange chromatography, precipitating yttrium oxalate with oxalic acid, converting the oxalate to oxide by heating under oxygen, and reacting the oxide with hydrogen fluoride to obtain yttrium fluoride.