'societe De Prayon'

Engelhard Wilhelm Pavonet

Process for purifying an iron containing zinc sulfate solution which comprises precipitating iron from said solution as a slurry in at least one of the following forms at a pH which is maintained lower than 4: basic sulfate, jarosite or goethite; filtering said slurry on a planar horizontal filter and forming a cake on said planar filter; washing the cake directly on the planar filter with water supplied onto the cake without forming a newslurry with washing water and thus freeing the cake from water soluble zinc and copper compounds promptly before hydrolysis thereof insolubilizes said compounds as basic sulfates, whereby the solid residue in the cake does not contain substantially more insoluble zinc content than it contained in the slurry being fed to the filtration.

Process for purifying a zinc sulfate solution

A method for purifying phosphoric acid obtained with sulfuric acid acting on natural phosphates, comprises extracting the phosphoric acid with a mixed solvent formed essentially by 95% to 50% by volume of an ether containing 5 to 7 carbon atoms, and by 5% to 50% by volume of at least one of the esters resulting from the reaction of the phosphoric acid with alcohols having 3 to 5 carbon atoms.

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Flemalle-Haute, Belgium

Engelhard Wilhelm Pavonet