| 摘要 |
A coal treatment underflow of an aqueous slurry of fine solid particles is dewaterized by first adding to the aqueous slurry a preferably high molecular weight flocculant lyophobic to water and lyophilic to fine solid particles to form a mixture. The mixture is charged to a thickener where flocculated solids are settled from the mixture and water separated from the mixture. During settling, the flocculated solids are preferably subjected to increased settling area and changing direction of liquid flow to increase the settling rate of the flocculated solids. A radiation beam is impinged on the flocculated solids transverse the direction of travel of the solids adjacent the discharge means from the thickener, and the impinged radiation beam is detected by detector means to continually measure the density of the flocculated solids preferably by degree of absorption of radiation. The detector in turn produces an electrical signal proportional to the density of the flocculated solids that automatically regulates and controls the rate of discharge of the flocculated solids from the thickener.
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