Alcan Research and Development Limited

James D Zwicker

Ghyslain Dube

An on-line particle size analyzer which is able to take measurements on material flowing along a line in real time and thus enable automatic process controls to be effected. The apparatus periodically takes a sample of material, dilutes it to a predetermined concentration in a turbidimeter, and then passes it to one of a number of vertical sedimentation cells in which a particle size analysis is carried out. Each sedimentation cell is formed simply as an enlarged part of a line passing from the turbidimeter around a loop back to the turbidimeter and, in order to fill the respective sedimentation cell, the sample is pumped round the loop until steady-state conditions have been reached, whereupon the flow is stopped and measurements begun. When the measurements, which are carried out by optical means, are completed, the whole loop, including the sedimentation cell is automatically flushed out. A central control unit controls the sequence of operations, and enables virtually continuous monitoring of the material flowing down the line.

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Arvida, Canada

James D Zwicker