Ammonium polyphosphate sulfate fertilizers from wet-process phosphoric acid

An improved process for preparing ammonium polyphosphate sulfate suspensions, which suspensions are eminently suitable for use in frigid climates, which process consists essentially of simultaneously supplying, at a temperature range of about 50.degree. F. to about 200.degree. F., a stream of anhydrous ammonia to the common pipe-cross section of a pipe-cross reactor, substantially all enthalpy added thereto over and above that supplied by the ambient temperature environment being supplied by heat exchange means communicating with a later mentioned liquid fertilizer reactor means;

• simultaneously supplying, at a temperature range of about 50.degree. F. to about 200.degree. F., a stream of merchant-grade 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 50 percent to about 58 percent, substantially all enthalpy added thereto over and above that supplied by the ambient temperature environment being supplied by heat exchange means communicating with a later-mentioned liquid fertilizer reactor means;
• simultaneously supplying, at a temperature range of about 50.degree. F. to about 100.degree. F., a stream of sulfuric acid to said cross section of said pipe-cross reactor, said sulfuric acid containing from about 90 to about 130 percent by weight 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 and in predetermined quantities relative to one another to effect in the resulting molten ammonium polyphosphate sulfate formed in a later-mentioned step an N:P.sub.2 O.sub.5 ratio ranging from 0.35 to about 0.39;
• subsequently introducing reaction product resulting from contacting said anhydrous ammonia, phosphoric acid, and sulfuric acid into a 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 polyphosphate sulfate and introducing said discharged sulfate into liquid fertilizer reactor means;
• simultaneously with said introduction of said sulfate, introducing into said liquid fertilizer reactor means a stream of aqueous medium in quantities to supply water of formulation thereto sufficient to effect the formation of liquid fertilizers nominally of grades 12-30-0-(2-8)S;
• subsequently adding to said nominal grades of 12-30-0-(2-8)S about 11/2 percent by weight gelling clay;
• intimately mixing said clay with said liquid fertilizer and effecting the formation of a resulting liquid fertilizer suspension product;
• said resulting liquid fertilizer suspension product characterized by the fact that the solidification temperature thereof is about -25.degree. F.