The invention pertains to a method of inertising free soluble impurities
of phosphates and/or fluoride ions, in phosphogypsum, for use in
commercial and industrial applications. The Phosphogypsum is
pre-conditioned over an extended period of time separately or treated
along with standard constituents by spraying, interblending or
intergrinding during the process of manufacture, with alkyl, alkenyl
and/or alkanol derivatives of ammonia, either individually or in
combination with one another, to form stable intermediary phosphates
and/or fluoride salts of the derivatives of ammonia.