GB729243A - Method of producing ammonia-phosphorus pentoxide reaction products - Google Patents

Abstract

<PICT:0729243/III/1> An ammonia-phosphorus pentoxide reaction product is produced by treating gaseous phosphorus pentoxide with substantially anhydrous gaseous ammonia at a temperature of 240 DEG C. to 725 DEG C. and then rapidly cooling the product to a temperature below 200 DEG C. The product may be calcined by maintaining in an atmosphere of ammonia at 20 DEG C. to 300 DEG C. for one to three hours. The reaction may be carried out at a temperature of 240 DEG C. to 500 DEG C., preferably 325 DEG C. to 350 DEG C. employing a molar ratio of ammonia to phosphorus pentoxide of 2.2 : 1 to 3.2 : 1, in which case a highly soluble product is obtained on calcining, preferably at 100 DEG C.; or at a temperature of 500 DEG C. to 725 DEG C., preferably 675 DEG C. to 700 DEG C., employing a similar molar ratio, in which case the calcined product is moderately to substantially insoluble, the minimum solubility being obtained by calcining at 250 DEG C. to 300 DEG C. If the ammonia to phosphorus pentoxide intermediate is produced at 500 DEG C. to 600 DEG C., the calcination is preferably carried out below 120 DEG C., or by heating to 175 DEG C. to 225 DEG C. for 10 to 20 minutes, screening the cooled product and calcining at 250 DEG C. for one hour. If the reaction takes place at 600 DEG C. to 725 DEG C., calcining at 250 DEG C. is preferred. A product having useful water-resistant properties or for use as a flame-proofing agent or speciality fertilizer is produced by reaction at 675 DEG C. to 700 DEG C. and calcined for one hour at 100 DEG C. Calcining of either the high or low solubility form in the presence of an atmosphere of 100 per cent. by volume ammonia is preferred, though air, nitrogen or another inert gas may be present. A number of examples is given, in which the apparatus of Fig. 1 is used. In this apparatus molten phosphorus is introduced by line 2, whilst an excess of air is injected tangentially through line 1. The products pass through tube 5 and come into an insulated zone equipped with electrical windings to heat said products to a suitable temperature indicated by means of thermo-couples in wells 9 and 11. Ammonia is introduced through pipe 13 and a pipe in the opposite side (not shown). The complex passes through the air, or otherwise cooled zone 14 where it is cooled to a free flowing white powder which passes into the collecting chamber 15 and is separated from the gaseous products by means of filter 16. The sojourn time from the introduction of ammonia to removal of reaction product is 3 to 5 seconds or less.