Method of treating phosphate-containing material to reduce problem with clay swelling

Abstract From the Canadian patent

In a method of treat- ?-containing phosphate rock comprising at least mining the phosphate rock, reducing the phosphate rock to a predetermined size range, adding water to the phosphate rock and storing the admixture containing at least the phosphate rock and water; the improvement characterized by adding to the admixture an amount effective to control problems associated with the swelling of residual clays of a chemical treatment selected from the class consisting of aliphatic hydroxy acids containing 2-6 carbon atoms inclusive, of which, citric acid and tartaric acid are members; the aliphatic hydroxy acid salts, and effective blends of the aliphatic hydroxy acid salts with a strong …