| abstract |
The invention relates to a method for producing soluble acid polyphosphates with an Na/P ratio of 0.3 to 0.6, a P2O5 content of over 77 %wt., a Na2O content of under 20 % and a residual water content of 3-10 %. The invention is characterized in that an aqueous phosphate solution is dried in order to form chain-like polyphosphates with an average chain length of 10 to 30, and then fused for 30-180 minutes at temperatures of 400-600 DEG C. The fusion is cooled, forming a vitreous product. During fusion, steam pressure of 0.1 to 0.5 bar is maintained in the atmosphere in contact with the fusion. The invention also relates to the polyphosphates produced by this method and to their use. |