Mississippi Chemical Corporation

Agrico Chemical Company

Daniel P McDonald

Kenneth L Parks

Kyle D Clevenger

David Arnold

James C Wade

The invention relates to a process for the conversion of a calcium mineral into a calcium containing solid product and a gaseous stream which comprises subjecting the calcium mineral to a temperature in excess of about 3400 degrees Fahrenheit for less than one minute.

Conversion of calcium compounds into solid and gaseous compounds

A method of preparing a purified ammoniated phosphoric acid composition, comprising, reacting an aqueous wet process phosphoric acid with an ammonium ion source at a N/P.sub.2 O.sub.5 weight ratio ranging from about 0.06 to about 0.15 in the presence of solid phase metal ion containing impurities for a time sufficient to precipitate the majority of the impurities in the acid, the impurity precipitation comprising at least several complex metal salts at least one of which contains magnesium, aluminum and fluorine, and obtaining the purified ammoniated phosphoric acid by separating the precipitated impurities therefrom.

Process for removing impurities from wet process of phosphoric acid

Magnesium and aluminum impurities may be removed from wet process phosphoric acid by adding a fluoride ion donating compound, such as hydrofluoric acid, for example, to thereby provide about four fluoride ions for each aluminum ion. Also, preferably, an aluminum ion donating compound, such as alum is added to the wet process acid to bring the aluminum ion to magnesium ion ratio up to about two to one to facilitate formation of crystalline compounds having the general stoichiometry MgAl.sub.2 F.sub.8. The treated filter grade acid is then further treated in a crystallizer to form large crystals which will readily precipitate so the purified liquid phase, low in magnesium and aluminum containing impurities, may be separated from the crystalline phase.

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Yazoo City, MS, United States of America

Daniel P McDonald