Date on Master's Thesis/Doctoral Dissertation


Document Type

Master's Thesis

Degree Name

M. Eng.


Chemical Engineering

Committee Chair

Morel, R. W. F.

Committee Co-Chair (if applicable)

Williams, Gordon C.

Committee Member

Barnes, W. R.

Committee Member

Ernst, Robert Craig


Fertilizers; Phosphates


Simultaneous drying of curing superphospate is shown to be of definite value in increasing the available P2O5 content. Raw superphosphate heated to 80 degrees C., and analysed after 1 hour, 4 hours, 24 hours, and 48 hours of curing contained 16.92%, 19.67%, 20.66%, and 20.78% of available P2O5 respectively. For the same periods of time samples cured at room temperature contained 15.28%, 17.1%, 17.7%, and 18.82% of available P2O5. There was a larger amount of P2O5 available after 4 hours heating than after 48 hours at room temperature. This increase represented a 12:1 time-ratio in favor of the heated sample. The increase in available P2O5 was apparently accomplished by drying since little further reaction of acid and rock occurred, as indicated by an essentially constant citrate insoluble content of about 2%. For commercial purposes, it is indicated that drying should be discontinued, or the drying temperature decreased, when the product has a moisture content of approximately 3-4%. This procedure will prevent excessive evaporation of the liquid phase and allow the continued action of the acid on the remaining rock, with a resultant reduction in the insoluble fraction of the rock.