THE QUANTITATIVE EVALUATION OF A GRANULATION MILLING PROCESS (COMMINUTION, MICROCOMPUTER, DATA ACQUISITION)

JOHN JOSEPH MOTZI, Purdue University

Abstract

The processing variables associated with the comminution of pharmaceutical tablet granulations were investigated. The three variables chosen were mill speed, output screen size and impeller type using a Quadro Comil(REGTM). Experiments performed on an aspirin granulation showed that the three mill variables cannot be considered independently but rather at the level of the combinations. A characterization of the mill output according to particle size was then possible based upon these combinations of mill variables. Polynomial regression models were constructed for each impeller type using mill speed and output screen size as the independent variables. The models were used to predict the mean particle size and geometric standard deviation of particle size distributions resulting from the comminution of aspirin. The predictions were found to compare well with the observed values. Further studies were undertaken to evaluate the relationship between the mill variables, total energy consumption and particle size reduction. A computer aided data acquisition system was employed to collect dynamic measurements from the mill. The data acquisition system consisted of a Zenith Z-150 microcomputer system, a Data Translation DT2805 data acquisition system and appropriate software. Torque measurements were collected from the drive shaft of the mill as well as measures of mill speed and flow during comminution. From these measurements it was possible to compute the amount of energy used in milling. Relationships were then found between the mill variables, energy used in milling and particle size reduction. The information collected and the models developed may be useful in the design and validation of milling processes and comminution equipment.

Degree

Ph.D.

Subject Area

Pharmaceuticals

COinS