| 摘要 |
PURPOSE:To recover zinc contg. substantially no fluorine at a high yield by adding slaked lime or calcium carbonate to an aq. acidic soln. of sulfuric acid contg. zinc and fluorine to adjust stepwise the pH thereof and filtering the formed precipitate at each stage. CONSTITUTION:Slaked lime or calcium carbonate is added to an aq. acidic soln. of sulfuric acid contg. zinc and fluorine to be byproduced after recovery of variable materials such as copper, etc. from the smoke and ashes generated in smelting of copper to adjust the pH thereof to 5-6.5. The formed precipitate is separated and gypsum and fluoride are thoroughly removed thereform. The above-mentioned alkali is further added to the filtrate to adjust the pH thereof to 7-7.5. The formed precipitate is filtered and zinc is recovered in the form of zinc hydroxide. Recovery of zinc at a high yield of about 95% is thus made possible and the resulting zinc contains substantially no fluorine and is adequate as a raw material for refining of zinc.
|
