CHARACTERISTICS OF FLOCCULES OF CLAY-SALT SLUDGE FORMED BY POLYACRYLAMIDE AND ITS COPOLYMERS
Abstract
The main characteristics of aggregates formed during the flocculation of clay-salt slurry using polyacrylamide-based polymers with various types of charge and molecular weights were studied using a laser analyzer of particle size Lasentec D600L of the FBRM system. The effect of the polymer type on the size of the floccules formed and their density was shown. It has been established that when using non-ionic polyacrylamide and its anionic copolymers floccules with a size of 500-600 mm are formed, and when flocculated with a cationic reagent, the floccules do not exceed 300 mm It was shown that an increase in the molecular weight of the cationic polymer does not contribute to an increase in the size of the aggregates of the clay slurry particles. It has been proven that with the use of non-ionic polyacrylamide and its anionic copolymers, the density of floccules significantly decreases with increasing their size, which is an important property of fractal aggregates. If the charge density of anionic polymers increases, the aggregates density decreases, due to electrostatic repulsion between the negatively charged polymer and the negatively charged surface of the sludge. Analysis of the kinetics of the clay sludge flocculation process showed that when using non-ionic and anionic polymers, fast flocculation occurs, and the number of primary particles in the aggregate does not exceed several units. When using a cationic polymer, the filling of the intraflouclear volume with primary particles occurs due to the displacement of the liquid phase, which contributes to the formation of dense and compact floccules. The results obtained can be used for the selection of flocculant in order to improve the process of thickening clay-salt sludge in the production of potash fertilizers.
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