Power consumption profile analysis and tensile strength measurements during moist agglomeration

This study was performed to elucidate the influences of process and formulation design on the granulation process using power consumption and tensile strength measurements. In order to record and analyze the power consumption profile "in process" a computer program was developed to be used for optimal end-point control in reproducible granule production. The program analyzes and calculates a characteristical point, the turning point of the S-shaped ascent of the profile. The tensile strength expresses the cohesiveness between the powder particles, which is dependent on saturation and capillary pressure. In order to investigate the influence of the amount of liquid present in the granular material on tensile strength a device was developed. The maxima of tensile strength occurred at 90% saturation, whereas the maxima of power consumption were determined at 100% saturation. The measured tensile strength sigma (N/m(2)) equals to the volume specific cohesion (J/m(3)). The present work proved that the power consumption measurement is an alternative, simple and inexpensive method to determine the cohesion of powder particles. The turning point is introduced as a signature of the starting material and furthermore as a parameter for the cohesiveness of the starting material and therefore for optimal end-point detection at an early stage. (C) 2002 Elsevier Science B.V. All rights reserved.