The present invention relates to a method for producing a phosphate-containing anti-corrosive pigment, to the phosphate-containing anti-corrosive pigment obtainable by this method, and to the use of the phosphate-containing anti-corrosive pigment for passive protection against corrosion.

This disclosure provides a two-step process to produce monocalcium phosphates from lime water treatment plant lime softening residuals and from other sources containing calcium salts. This patent focuses on the reuse of lime softening residuals to produce monocalcium phosphates and dicalcium phosphates for use in a variety of applications including as quick release and slow release fertilizers, for animal feed and other applications. The two-step process is conducted close to ambient temperatures and under controlled pH conditions to produce substantially pure calcium phosphate products while at the same time capturing the carbon dioxide generated in the process.

A method of producing ammonium phosphates from at least one mineral containing phosphate and an element which is calcium, magnesium, iron, or aluminum. The method includes contacting the at least one mineral (or a combination of them) with a cation exchanger for a time and at a temperature sufficient to yield phosphoric acid from the mineral.