Interaction between Feeding and Compaction during Lactose Compaction in a Laboratory Roll Press

Abstract

Experimental work was carried out to determine the influence of operating parameters on the roll press compaction of lactose and the interactions between feeding and compaction. A laboratory roll press was specially instrumented. The press and instrumentation are described. The first part of the experimental work deals with the adjustment of the roll press parameters in order to produce compacts with good mechanical strength and aspect for several roll press throughput. The measured normal stresses applied to the powder, the roll gap variations and the roll press throughput are correlated with the ratio between the speed of the rollers and the screw feeder speed, also called work coefficient. The roll press throughput is principally governed by the screw feeder speed. The second part of the experimental work deals with characterisation of the influence of the feeding conditions on the compaction. The single screw feeder produces locally a periodic disturbance which is responsible for compact heterogeneity. The normal stress measured on the rollers was correlated with the period of the screw. A minor variation of the feeding pressure produces a great variation of the compaction stress.