Fertilizer Technology, Production of Ordinary Superphosphate for Immediate Use in Ammoniation and Granulation Processes

Abstract

Small-scale tests of the reaction of phosphate rock with sulfuric acid resulted in the identification of conditions that yielded superphosphate of high phosphorous pentoxide availability and of such physical condition that it could be ammoniated about 1 hour after mixing. These results were verified in a pilot plant that consisted of a TV A funnel-type mixer and a continuous den. A conversion of 95% was achieved in 1 hour by slightly overacidulating finely ground rock with acid of about 60% concentration. Fresh superphosphate from the den was used immediately in the production of several grades of granular fertilizers by the TV A continuous ammoniation process. ORDINARY superphosphate, made

Fertilizer Materials, Exploratory Studies of Hydrolysis and Ammoniation of Calcium Metaphosphate

“…H20] was a major phase. This is one of the phosphatic compounds recently identified in ammoniation products of hydrolysis of calcium metaphosphate (7). Other compounds found were monoammonium phosphate and calcium phosphate more basic than dicalcium phosphate.…”

Plant Practice in Granulation

“…The main differences in drying practice are in the type of solids-gas flow' and the size of the drum. In a typical group of 41 plants, about 60% of the dryers were of the cocurrent type, involving parallel flow of combustion gas and solids. The remainder were of the countercurrent type.…”

“…An integrated process for producing superphosphate and granular fertilizer in a continuous operation has shown some promise in tests at TVA (41).…”

Effect of Basic Process Variables on Phosphate Fertilizer Production

“….^Vcidulation of phosphate rock with sulfuric acid to make superphosphate requires a curing period of several weeks for an acceptable degree of reaction. Interest in accelerating the reaction is reflected in a recent study of major reaction variables (14) and in work on a process for ammoniating superphosphate directly after denning (19). Quick curing of superphosphate by drying has also been studied (6)(7)(8)15).…”