Purification and conversion of phosphoric acid to ammonium phosphates

A process for purifying wet-process phosphoric acid, which process employs the use of acetone and a source of ammonia, and which process comprises the following steps:

• (1) introducing into first reacting means streams comprising acetone from later-mentioned filtering means, condensing means, and distillation means, a stream of phosphoric acid and a stream of a source of ammonia to produce a resulting reaction slurry therein;
• (2) maintaining a temperature in said first reacting means above 50.degree. C. and maintaining the material therein for a period of time ranging from about 45 minutes to about 120 minutes;
• (3) removing at least a portion of said slurry from said first reacting means and introducing same into first filtering means wherein the solids are separated from the liquid in said reaction slurry formed in said first reacting means supra;
• (4) recovering said separated solids from said first filtering means and washing same with acetone to effect the removal of the residual mother liquor phosphoric acid adhering to the surfaces thereof;
• (5) removing the wash effluent comprising acetone and residual phosphoric acid mother liquor from said first filtering means and introducing same into said first reacting means;
• (6) removing the recovered separated solids from said first filtering means and introducing same into drying means, wherefrom is recovered a resulting dried solid fertilizer product and wherefrom is evolved offgases containing residual acetone;
• (7) introducing said acetone containing offgases from said first drying means into condensing means to effect the condensation and recovery of said acetone therein and subsequent introduction of said recovered condensed acetone into said first reacting means;
• (8) removing the filtrate from said first filtering means and introducing same into a second reacting means together with a stream of ammonia to produce therein a slurry, said ammonia introduced into said second reacting means being so proportioned as to provide therein a mixture of ammonium phosphate having a mole ratio NH.sub.3 :P.sub.2 O.sub.5 of about 2;
• (9) removing from said second reacting means at least a portion of the resulting slurry formed therein and introducing same into second filtering means;
• (10) recovering the solids of ammonium phosphate from said second filtering means and introducing same into drying means wherefrom is recovered dried solid ammonium phosphate fertilizer product and an offgas containing residual acetone;
• (11) introducing said residual acetone containing offgases into condensing means wherefrom the resulting recovered condensed acetone is introduced into said first reacting means;
• (12) removing the filtrate from said second filtering means and introducing same into distillation means wherefrom is recovered distilled acetone, which distilled acetone is subsequently introduced into said first reacting means.