| 摘要 |
<p>A process for the removal of heavy metal ions and particularly cadmium and copper from phosphoric acid of a concentration in the range of 20% to 52% by wt P2O5 is described. The process consists in a treatment of phosphoric acid with a reducing agent and a thio-organophosphene reagent, the heavy metal ions being retained on a solid adsorbent. According to one embodiment the process is carried out during the production of wet-process phosphoric acid, the calcium sulfate co-produced being the adsorbent. According to another embodiment,a solution of phosphoric acid, obtained by mixing a filter acid phosphoric acid with a more concentrated phosphoric acid solution, is treated according to the process, using an adsorbent selected from the group consisting of calcium sulfate, active carbon and aluminum silicates. The thio-organophosphene reagents are selected from tri-n-propylphosphene sulfide, diisobutyl dithiophosphene sulfide, tri-n-octylphosphene sulfide, dicyclohexyl phosphene sulfide, diisobutyl dithiophosphinate and dicylcohexyl dithiophosphinate.</p> |
