CAKING IN AMMONIUM PHOSPHATE FERTILIZERS

An experimental study was undertaken to determine the relationship between caking of ammonium phosphate fertilizer grades 13-5.7-10.8 (13-13-13) and 12-7-13.3 (12-16-16) and the titration mole ratio (NH3/H3PO4) and moisture content of the fertilizer. Work was also done toward identifying the bonding-phase material causing caking. The caking tendency of 13-5.7-10.8 grade decreases as the mole ratio increases from 0.9 to 1.16; further increase causes an increase in caking to a mole ratio of about 1.28. Caking of the 12-7-13.3 grade decreases as mole ratio increases from 0.9 to 1.05; further increase to 1.08 causes caking to increase. If the mole ratio is increased above the values of 1.28 and 1.08, caking decreases. A salt complex of the general formula K(2-x)(NH4)xSO4 · ZH2O is credited with causing caking in the fertilizer grades tested near the critical mole ratio (1.16 for 13-5.7-10.8 and 1.05 for 12-7-13.3). © 1969, American Chemical Society. All rights reserved.