Abstract: A method of preparing potassium magnesium phosphate hexahydrate by reacting calcium dihydrogen phosphate with potassium sulfate and a basic magnesium compound is described.

Abstract: Process for producing potassium magnesium phosphate by reacting basic magnesium compounds with phosphoric acid or phosphates in the presence of potassium sulfate from a mother liquor containing per 1000 g water up to 150 g magnesium sulfate and up to 120 g potassium sulfate. Precipitation forms with addition of calcium oxide or hydroxide equimolar to present magnesium sulfate and after phosphoric acid adjustment of the pH to 2-4, mechanical separation and addition of potassium sulfate and basic magnesium compounds, the desired product results.

Abstract: For the production of potassium magnesium phosphate from phosphoric acid, potassium salts and basic magnesium compounds, these are reacted in a mixture of recycled mother liquor from the potassium magnesium phosphate crystallization and of fresh water, with adjustment of the pH-value of the reaction mixture to 7.2 up to 8.5 through addition of quickly reacting basic compounds, in the presence of potassium magnesium phosphate seed crystals, whereupon the product is separated from the mother liquor and from this a part is recycled to the process start, and the rest is removed.

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.