Process for making alkali metal polyphosphates

TLDR: In this paper, a process for making alkali metal polyphosphates was described, where a fine particulate solution or suspension was forced through at least one nozzle and then sprayed inside a spray tower through a flame zone produced by one or more burners arranged in annular fashion.

Abstract: The disclosure relates to a process for making alkali metal polyphosphates, especially alkali metal triphosphates. To this end, the disclosure provides for an alkali metal phosphate solution or suspension to be forced through at least one nozzle and for them to be sprayed inside a spray tower through a flame zone produced by a one or more burners arranged in annular fashion. More particularly, the disclosure provides for fine particulate alkali metal polyphosphates, especially alkali metal triphosphates, to be additionally introduced into the spray tower from above and for them to be regularly distributed across the spray region(s) of the nozzle(s) with formation of agglomerated products. The disclosure also relates to an apparatus for carrying out the process. The apparatus is comprised of a cylindrical spray tower (1) having a tapered lower end (3) and being closed by means of a cover (2); a spray means (6) being passed centrally through the cover (2); a plurality of burners (11) and a solid matter feed means being passed through the cover concentrically with respect to the spray means (6) and so as to be spaced therefrom; and a bevelled issuing gas outlet (4) opening upwardly from the tapered end of the spray tower (1).