Alcan International Limited

Jean Doucet

Kwat I The

David R Chinloy

Leopold Tremblay

Pierre Ferland

Michael A McKenzie

A testing device is described for use in determining optimum operating conditions for a full size industrial continuous gravity settling unit and for the design of such settling unit. The testing device comprises an elongated, cylindrical settling column having concentric, inner and outer transparent cylindrical walls forming an annular space therebetween filled with transparent heat exchange liquid, with the inner wall defining a cylindrical settling cell. A cylindrical feedwell extends downwardly into the top end of the settling cell, an overflow outlet opening is provided in the inner wall at a location above the bottom end of said feedwell, a solids discharge opening is provided at the bottom of the settling cell and a rotating rake is provided at the bottom of the settling cell for compacting collected solids. The device also includes pump means for providing smooth, continuous flows of slurry and flocculant, mixing means for mixing together the slurry and flocculant, and means for measuring and controlling flow rates and temperatures. The testing device is utilized by observing the position and shape of a stream of agglomerated solids leaving the bottom of the feedwell of the settling column and adjusting the flow rate of at least one of the flow rate of the stream of suspended solids and the flow rate of the stream of flocculating agent to the settling column such that the stream of agglomerated solids leaving the feedwell displays hindered settling, and utilizing the adjusted flow rates of the suspended solids stream and the flocculant stream to determine the optimum operating conditions for an industrial settling unit.

Process and apparatus for controlling gravity settling system

In a process for biodegrading under highly alkaline conditions organics in a waste stream derived from a Bayer processing system for producing aluminum oxides,

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Jonquiere, Canada

Jean Doucet