From: Redaktion BSH (BulkSolidsHandling)
Using the optimum method to characterise electrostatic behaviour helps to avoid unwanted phenomena as agglomeration, segregation, etc., to improve production processes and product properties.
Generation of electrostatic charge during industrial powder handling processes may give rise to unwanted particle cohesion or adhesion, which in turn results in difficulties such as agglomeration, segregation, material build-up on equipment, etc. Its impact is felt in terms of lower production yields and increased process downtime. These problems are particularly severe for the pharmaceutical industry, where particle sizes are often smaller than 20 µm meaning electrostatic forces are likely to dominate gravitational force.
This review paper firstly discusses the causes and effect of electrostatic charge to the pharmaceutical industry, and then mechanisms by which electrostatic charging occurs. Foremost is tribocharging which arises from particle-particle and particle-wall contacts. Its behaviour is erratic and not easy to predict, nevertheless it is desirable to characterize the charging tendency of pharmaceutical raw materials so that corrective action can be taken prior to full scale manufacture. To this end the principal charge measurement techniques are reviewed.
On the basis of the review it is concluded that there is a need for a practical technique to measure the polarity of individual particles. Finally, a probe for this purpose is described here, whilst its development is the subject of ongoing research.
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Published: 09/15/2010 | Redaktion BSH (BulkSolidsHandling)