method and device for measuring fine particles from a suspension of entflockungsgrades

摘要

1,168,668. Centrifugal separators. ENGLISH CLAYS LOVERING ,POCHIN & CO. Ltd. 1 Aug., 1968 [7 Aug., 1967], No. 36220/ 67. Heading B2P. [Also in Divisions G1 and G3] A centrifuge for measuring the deflocculation of a clay suspension comprises two compartments having windows for the passage of light through the compartments and photoelectric means for comparing the optical density of material in the compartments. The centrifuge comprises a flat disc 2 and a disc 1 recessed to form the compartments A, B. The discs are held together by hydraulic cylinders 10 fixed to disc 2 and having pistons 17 connected to disc 1 by a frame 16 and posts 15. Hydraulic fluid is supplied through conduits 18, 19, 20, and when the supply is cut off springs 11 separate discs 1 and 2 to eject the material in the compartments. Truncated concentric cones 4, 5 communicate with the respective compartments to permit filling while the centrifuge is running. Each compartment has windows 6, 7 and a pair of photocells 8 and a ring of lamps is arranged above the windows 6. Deflocculation control. A stream of clay suspension to which has been added deflocculant is sampled and the sample split into two. Sufficient deflocculant is added to one portion to completely deflocculate it and the portions are fed to the centrifuge compartments. A self-balancing bridge circuit includes one of the cells 8 under each of the compartments. The other photocell under the completely deflocculated portion of the sample is a control photocell which varies the lamp brightness to maintain the light intensity on the photocells under the completely deflocculated portion substantially constant. After centrifuging for a time determined in accordance with the initial solids concentration by the control photocell, the position of the balance element of the bridge indicates the optical density ratio of the two sample portions which ratio depends on the deflocculation of the sample. The measured value is recorded and compared with a desired value to produce an error signal to drive a motor controlling the setting of a valve in the deflocculant supply to the main suspension stream. The centrifuge is then emptied and washed with water several times.