PROCESS FOR THE MANUFACTURE OF FINELY DISPERSED SPARINGLY SOLUBLE SALTS OF OXYACIDS OF PHOSPHORUS

摘要

ABSTRACT OF THE DISCLOSUREThe invention relates to a process for making a finely dispersed,sparingly soluble salt of an oxyacid of phosphorus, having a maximum parti-cle size of 20 µm, by reacting a compound of a divalent metal with the oxy-acid of phosphorus or an alkali metal or ammonium salt thereof. More partic-ularly, finely dispersed salt consisting to an extent of at least 90% of par-ticles with a size between 0.05 and 7 µm is made. To this end, an at least5% by weight aqueous solution or suspension of a compound of a divalent metalselected from the group Mg, Ca, Sr, Ba, Mn, Zn, Cu, Cd, Pb, Sn, Co and Ni isreacted, while maintaining a pH range of between 3 and 9 and while stirring,with an at least 2 mol% solution of at least one trivalent metal selectedfrom the group Al, Fe and Cr in the oxyacid of phosphorus and, optionally,with an aqueous solution of an alkali metal or ammonium salt of the oxyacidof phosphorus, and the precipitated salt is separated off and dried.