Granular ammonium phosphate sulfate and urea-ammonium phosphate sulfate using a common pipe-cross reactor

An improved process for preparing granular substantially dust-free ammonium phosphate sulfates of a particle size distribution eminently suitable for subsequent bulk blending with other fertilizer values, which process consists essentially of simultaneously supplying a stream of anhydrous ammonia to the common pipe section of a pipe-cross reactor;

• simultaneously supplying a stream of phosphoric acid to the cross section of said pipe-cross reactor, said phosphoric acid having a P.sub.2 O.sub.5 content in the range from about 30 to about 52 percent by weight and a free water content ranging from about 15 to 55 percent by weight;
• simultaneously supplying a stream of sulfuric acid to said cross section of said pipe-cross reactor, said sulfuric acid containing from about 78 to about 98 percent H.sub.2 SO.sub.4, said streams of phosphoric acid and sulfuric acid contacting said anhydrous ammonia introduced into said common pipe section of said pipe-cross reactor at said cross section of said pipe-cross reactor, at a temperature sufficiently high so that additional water is not necessary for continuous operation;
• subsequently introducing the reaction product resulting from contacting said anhydrous ammonia, phosphoric acid, and sulfuric acid into the vapor tube extension of said pipe-cross reactor to ensure continued intimate contact therebetween;
• subsequently discharging from the downstream end of said vaporization tubular extension an essentially anhydrous molten ammonium phosphate sulfate into the upper end of an inclined rotating drum;
• therein maintaining a bed of rolling discrete particles of ammonium phosphate sulfate;
• withdrawing ammonium phosphate sulfate material from the lower end of said inclined rotating drum;
• introducing said withdrawn material into cooling means;
• withdrawing the resulting cooled material from said cooling means;
• introducing said material withdrawn from said cooling means into sizing means;
• returning particles of predetermined size from said sizing means into the upper end of said drum and withdrawing from said sizing means granular particles of ammonium phosphate sulfate as product;
• said process characterized by the fact that there is a reduction in moisture content ranging from about 0.1 to about 1.2 percent by weight of said ammonium phosphate sulfate by said step of removing same from the lower end of said inclined rotating drum to the step of recovery of same as product, said percent reduction in moisture content based on the moisture content of said ammonium phosphate sulfate as it leaves the lower end of said inclined rotating drum and caused by evaporation while said material is being cooled.