| 摘要 |
<p>Zinc (Zn) containing waste derived mainly from flame-galvanizing is dissolved in acid- or base-media. When high concentrations of metallic Zn are present, it is preferable that a large proportion of Zn should remain undissolved. This is achieved by addition of only small vols. of acid at a time, so, that the pH should not fall permanently below pH 3-4 and in case of addition of a base, the pH should not rise permanently above pH 11-12. Zn waste solutions are treated with alkali-(ammonium hydroxide, -hydrogen carbonate, or -hydroxide), yielding aqueous insoluble Zn-carbonate or Zn-hydroxide. Aqueous insoluble Zn-carbonate and Zn-hydroxide are valuable raw materials for paint and intermediates for the chemical industries.</p> |
