摘要 |
<p>Wet process phosphoric acid is freed from heavy metal ions, especially from ions of cadmium, copper, mercury, lead and arsenic and optionally also from organic compounds and sulfuric acid. To this end, the phosphoric acid is contacted with a diorganyldithiophosphoric acid ester and an adsorbent, if desired. Prior to or after said treatment with the ester, the phosphoric acid is admixed with a reductant. The adsorbent, if any is used alone or in combination with an alkaline earth metal compound soluble in phosphoric acid.</p> |