Hoechst Aktiengesellschaft

G/u/ Nther Schimmel

Reinhard Gradl

Gero Heymer

Werner Krause

Helmold Von Plessen

Phosphoric acid solutions are dearsenified by treating them with a sulfide and separating the resulting precipitate from the purified solution. The sulfide is at least one compound of the general formula P.sub.4 S.sub.x in which x stands for a number of 3 to 10.

Process for dearsenifying phosphoric acid solutions

The disclosure relates to a process for liquid/liquid-extraction of heavy metal ions from acid aqueous solutions with the aid of water-insoluble dithiophosphoric acid diesters as extracting agents. More particularly, use is made of phosphoric acid solutions with a P.sub.2 O.sub.5 -content of from 3 to 80 weight %, the solutions being free from emulsion-forming organic contaminants or having previously been freed therefrom in known manner. The resulting aqueous phase is separated from the phase containing the dithiophosphoric acid diester.

Process for extracting heavy metal ions from aqueous solutions

A process for the separation of heavy metal components, especially of compounds of cadmium, mercury and lead, from crude phosphoric acid obtained according to the Odda process, which comprises adjusting this crude phosphoric acid with ammonia to a pH of from 0.5 to 1.5, contacting it subsequently with a diorganyl-dithiophosphorus compound and an adsorbent, and then separating the acid from the absorbent containing the heavy metal impurities.

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Erftstadt, Germany

G/u/ Nther Schimmel