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US 4,324,774 AGranted
Method for the manufacture of defluorinated phosphatic products
AssigneeFertilizer Development S.A.
InventorAvraham M. Baniel
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AssigneeFertilizer Development S.A.
InventorAvraham M. Baniel
Estimating the term…
The present invention relates to a method for the manufacture of phosphatic products having a very low fluorine content from wet process phosphoric acid. According to the invention the fluorine in the wet process phosphoric acid is removed in the form of potassium fluosilicate, by the reaction of its fluoride components with KH.sub.2 PO.sub.4 formed insitu from KCl or K.sub.2 SO.sub.4 and an amine phosphate salt, the latter resulting from phosphoric acid and an amine selected from the group consisting of a primary--secondary--or tertiary aliphatic amine, a quaternary ammonium base or mixtures thereof. Examples of suitable amines and quaternary ammonium bases are: tri-n-octylamine, ethyl di-n-octylamine, di-n-dodecylamine, di-n-decylamine, tricaprylamine, tri-iso-octylamine etc. The amine constituent appears in the form of a water-immiscible liquid, preferably in conjunction with an organic solvent in which the aliphatic amines and their salts are soluble. The method is very flexible and enables the production of a range of upgraded phosphatic products of different purity grades according to the specific requirement, at yields which are substantially theoretical.
A method for removal of fluorine from wet-process phosphoric acid (WPA) prepared by acidulation of phosphate rock with sulfuric acid comprising reacting wet-process phosphoric acid with KH.sub.2 PO.sub.4 in a first unit to precipitate fluorine present in said wet-process phosphoric acid as potassium fluosilicate and produce clarified and substantially fluorine-free phosphoric acid, wherein said KH.sub.2 PO.sub.4 is formed in-situ by reacting in a second unit (i) an amine phosphate salt with (ii) a potassium salt selected from the group consisting of KCl and K.sub.2 SO.sub.4, and wherein said amine phosphate salt is formed in a third unit by reaction of (i) an amine which is present in a water-immiscible liquid system comprised of members selected from the group consisting of a primary, secondary, tertiary aliphatic amine, a quaternary ammonium base or mixtures thereof, said amine and/or quaternary ammonium base comprising at least two aliphatic hydrophobic groups each containing at least 7 carbon atoms directly attached to the nitrogen thereof, with (ii) a stoichiometric equivalent amount of a portion of the clarified and substantially fluorine-free phosphoric acid produced in said first unit.
Dependencies are inferred from the claim text.