二リン安を配合した粒状配合肥料(BB肥料)における固結と反応

抄録

Generally speaking, caking of granules is mainly caused by cross-linking of crystals grown from the surface of each chemical. This drawback is an important factor to be considered for maintaining the quality of BBFs. To delineate this, we have examined the caking process of the phosphate material, DAP. In the first sample, basic BBFs formula #1 which are mixed DAP, AS and muriate of potash, few new crystals were derived from materials by chemical reaction and a low degree of caking was found. The reaction products by X-ray diffraction were ammonium chloride and sulfate of potash. The traits of formula #2(basic BBFs formula #1 with urea)was urea ammonium chloride double salt other than the compounds found in formula #1. The hardness of caking and amount of powder crystals in formula #3(basic BBF formula #1 with triple super phosphate(TSP))were larger than those of formula #1 and #2. The compound newly formed in this sample was MAP and colloidal apatite. The hardness of caking of formula #4(formula #3 with urea)was lower than that of formula #3. Apatite and MAP were found mainly in the crystals, but double salt of CO(NH_2)_2・Ca(HPO_4)_2, which was often found in the reaction of urea with TSP, could not be detected. The effect of decreasing the temperature for caking was to make it harder than at a constant temperature condition for most of the formulas because new crystals were produced which linked tightly between particles decreasing the sluvility of the chemicals. To sum up, DAP in BBFs have little effect on caking and reaction in BBFs, except for the combinations of DAP and TSP, and TSP and urea. We speculate that the caking tendency of BBFs was influenced not in terms of the magnitude of reactions but the change of temperature.