Importance

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Abstract

A flocculation control system for controlling a feed rate of a flocculant into an aqueous slurry comprises an elongate settling tube having an open lower end for placing into the slurry. An air eductor creates a subatmospheric pressure within the settling tube to thereby draw a sample of the slurry therein to a predetermined location above the slurry level. A control valve hermetically seals an upper end of the settling tube to maintain the subatmospheric pressure therein such that the sample is retained in a quiescent state and in fluid communication with the slurry body. A pressure sensor senses the subatmospheric pressure within the settling tube, and measurements thereof are taken at selectable intervals to develop an initial measurement of said pressure and intermediate lower magnitude measurements of said pressure resulting from the settling of particles from the sample. The pressure measurements enable calculation of the weight concentration and settling velocity of said suspended particulates. A desired settling velocity for optimizing flocculant feed rate can be determined from the weight concentration of the suspended particles. The feed rate of the flocculant is increased if the measured settling velocity is lower than a desired rate and decreased if the measured settling velocity is higher than a desired rate.

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First Claim