摘要 |
Anhydrous hydrogen fluoride of high purity can be recovered from metallic fluoride salts containing phosphate values by digesting the metallic salts in an aqueous solution in a humid atmosphere at a sufficiently high temperature to release a gas containing hydrogen fluoride and negligible amount of P2O5. The released gas is rectified in a rectification operation which includes a rectification zone in which the rectification occurs in the presence of sulfuric acid. |