GB934436A - A new or improved process and apparatus for the production of ammonium phosphates - Google Patents

Abstract

In a process for producing ammonium phosphates, particularly di-ammonium phosphate, ammonia-containing vapours are distilled from ammoniacal liquor and passed at the reaction temperature (e.g. 65 DEG to 85 DEG C.) to a phosphoric acid bath maintained at the reaction temperature where ammonium phosphate crystals are produced and removed, and gases, air and water vapour are withdrawn from the bath, cooled to condense water, reheated to the reaction temperature and recycled to the phosphoric acid bath to evaporate excess water therefrom. Ammoniacal liquor (e.g. recovered from coal <PICT:0934436/III/1> carbonizing plants) is distilled in a still 1 (Fig. 1), the vapours are cooled to the reaction temperature in a dephlegmator 2, condensates being returned to the still 1, and passed into a phosphoric acid bath 3 (pH 5,0 to 6,5). The gases from bath 3 are partly cooled in a heat exchanger 5 by heat exchange with ammoniacal liquor being sent to still 1, further cooled in a cooler 6, condensates are removed, and a part of the gases are reheated at 8 and discharged into the phosphoric acid bath 3 through a spray ring 9. In modifications some gases are removed from the ammoniacal liquor before it enters the still, and the hot effluent from the still is used to reheat the recycled gases.