Hoechst Aktiengesellschaft

Herbert Ressel

Gunther R Schimmel

Reinhard Gradl

Friedrich Kolkmann

Gero Heymer

Hans Haas

Johannes Krause

Wilhelm Westphal

Crude phosphoric acid is made by subjecting crude phosphate ore containing sulfide to processing treatment with a mineral acid in a closed system comprised of a processing reactor, a filtering zone and an off-gas scrubbing zone. To this end, a soluble compound of a metal forming difficultly soluble sulfides in the respective acid medium is added either

Process for making crude phosphoric acid

Apparatus for reducing iron and vanadium in phosphoric acid solution with the aid of a granular reductant. The apparatus is comprised of a drum rotatable around its transverse axis. It is partially filled with the granular reductant and provided with inlets for supplying the phosphoric acid solution, the granular reductant and an inert gas, and also with a reaction product outlet.

Apparatus for reducing iron and vanadium in phosphoric acid solution

Wet-process phosphoric acid is made by subjecting a phosphate ore to processing treatment with a mineral acid resulting in the formation of a processed suspension. The formation of silicofluorides is obviated by adding, either to the phosphate ore or the processed suspension, a quantity of an aluminum compound soluble in phosphoric acid sufficent for the processed suspension to present an aluminum concentration of 0.3 to 1.0 wgt %, based on P.sub.2 O.sub.5.

Process for making wet-process phosphoric acid

Iron and vanadium is phosphoric acid solution are reduced. To this end, the phosphoric acid solution is contacted with ferrophosphorus which is used as the reductant.

Process for reducing iron and vanadium in phosphoric acid solution

The disclosure relates to a process for defluorinating alkali metal phosphate solutions. To this end, the disclosure provides for an alkali metal phosphate solution neutralized to a pH-value of more than 6 and pre-purified to be stirred at 60.degree. to 120.degree. C. into an alkaline earth metal compound. Alkaline earth metal compounds with a solubility in water of less than 5 g/l are used in the form of particles of which more than 50% have a size of less than 8 .mu.m. After a reaction period of 0.5 to 4 hours, the precipitate obtained is separated from the purified alkali metal phosphate solution.

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Erftstadt, Germany

Herbert Ressel