Process for the production of potassium magnesium phosphate
AssigneeKali and Salz Aktiengesellschaft
InventorKarl-Richard Loblich
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Abstract
A process for producing potassium magnesium phosphate from phosphoric acid, potassium chloride and magnesium oxide, carbonated or like alkaline magnesium compound, which comprises adding the magnesium compound to an aqueous solution of the phosphoric acid or the acidic soluble phosphate salt and an amount of potassium chloride in excess of that theoretically required, in an amount and at a rate such that the pH is maintained below 9 and a high ratio of potassium chloride to magnesium chloride is maintained in the reaction mixture, whereby the formation of tribasic magnesium phosphate is suppressed.
Claims17
A process for the production of potassium magnesium phosphate by the reaction of an aqueous solution of a source of acidic phosphate ions and potassium chloride with an alkaline magnesium compound which comprises the steps of:
- (a) adding under agitation to an acidic phosphate solution having a P.sub.2 O.sub.5 equivalent content of 20-167 g per 1000 g of water an amount of the alkaline magnesium compound which is approximately that required to convert the source of acidic phosphate ions to dibasic magnesium phosphate and a portion of the potassium chloride required to convert the dibasic magnesium phosphate to potassium magnesium phosphate;
- (b) thereafter adding thereto a further amount of potassium chloride which raises the potassium chloride content of the reaction mixture to a value from more than a K.sub.2 O:P.sub.2 O.sub.5 equivalent molar ratio of 1:1 to just below the saturation point;
- (c) thereafter gradually adding to the thus-produced suspension the amount of alkaline magnesium compound stoichiometrically required to convert the dibasic magnesium phosphate to potassium magnesium phosphate, at a temperature below 40.degree. C., the amounts of reactants being such that the concentration of MgCl.sub.2 in the reaction mixture does not exceed 130 g per 1000 g of water;
- and
- (d) separating the thus-produced potassium magnesium phosphate from the mother liquor.
A process for the production of potassium magnesium phosphate which comprises reacting under aqueous conditions and at a pH below 9 (a) mono or dibasic magnesium phosphate, (b) potassium chloride, and (c) an alkaline magnesium compound, in the presence of less than 130 g per liter of MgCl.sub.2 and other soluble magnesium compounds and in the presence of an amount of potassium chloride substantially in excess of the MgCl.sub.2 and other soluble magnesium compounds, whereby the production of tribasic magnesium phosphate is suppressed.
Dependencies are inferred from the claim text.