Abstract: The disclosure relates to a process for making phosphorus pentoxide by subjecting elemental yellow phosphorus to combustion with dried air inside a steel-made combustion chamber with utilization of the reaction heat for the production of energy.

Abstract: The disclosure relates to a process for making phosphorus pentoxide by subjecting elemental yellow phosphorus to combustion with dried air inside a steel-made combustion chamber with utilization of the reaction heat for the production of energy. To this end, the disclosure provides for the combustion to be effected inside a combustion chamber of which the walls are arranged so as to form a cooling system with cavities therein; for a liquid or liquid/steam-mixture as a heat carrier abstracting the reaction heat to be circulated through the cooling system, the liquid or liquid/steam-mixture assuming an increased temperature being preferably so circulated under increased pressure; for steam formed in the cooling system to be continuously taken therefrom; for an equivalent proportion of fresh liquid to be introduced into the cooling system; for hot P.sub.2 O.sub.