Russian Journal of Applied Chemistry, 2009, Vol. 82, No. 2, pp. 328−332.
Pleiades Publishing, Ltd., 2009.
Original Russian Text
V.F. Kurenkov, I.N. Nadezhdin, H.-G. Hartan, F.I. Lobanov, 2009, published in Zhurnal Prikladnoi Khimii, 2009, Vol. 82, No. 2,
AND POLYMERIC MATERIALS
Clariﬁ cation of a Dilute Suspension of Calcium Carbonate
in the Presence of Praestol Flocculants and Aluminum Sulfate
V. F. Kurenkov, I. N. Nadezhdin, H.-G. Hartan, and F. I. Lobanov
Kazan State University of Technology, Kazan, Tatarstan, Russia
Stockhausen GmbH, Krefeld, Germany
Ashland Eurasia Limited Liability Company, Moscow, Russia
Received September 18, 2008
Abstract—Kinetic features of clarification of 1% suspension of calcium carbonate under the action of coagulants
(aluminum sulfate, hydroxoaluminum chloride) and flocculants (nonionic, anionic, and cationic Praestols) were
studied in relation to the dispersed phase concentration, nature of the coagulant and flocculants, sequence and time
of their introduction into the suspension, and also molecular weight, chemical composition, and conformation of
macromolecules of anionic Praestol in solution.
Water-soluble polymeric ﬂ occulants [1, 2] and their
mixtures with coagulants [3, 4] are successfully used
for efﬁ cient dehydration and concentration of mineral
suspensions and for treatment of industrial wastewaters.
The most widely used are polyacrylamide ﬂ occulants
[5, 6], in particular, nonionic, anionic, and cationic
Praestols, and also coagulants: aluminum sulfate and
hydroxoaluminum chloride. For clariﬁ cation of calcium
carbonate suspensions used in production of paper,
plastics, ceramics, and paints, it is advisable to use
Praestol ﬂ occulants in combination with coagulants.
However, these processes are studied insufﬁ ciently.
Previously we examined the effect of cationic [7, 8] and
anionic  Praestols on the sedimentation stability of
dilute  and concentrated [8, 9] suspensions of calcium
carbonate. Here we report on a comparative study of
the performance of nonionic, anionic, and cationic
Praestols as ﬂ occulants and of aluminum sulfate and
hydroxoaluminum chloride as coagulants in clariﬁ cation
of a 1% suspension of calcium carbonate.
Experiments were performed with Praestols produced
by Ashland MSP Private Company: polyacrylamide
(PAA, nonionic), copolymers of acrylamide (AA) with
sodium acrylate (SA) (anionic), and copolymers of AA
chloride (APTMAC) (cationic). The characteristics of
the Praestols are given in the table. Copolymer samples
with different molecular weights but the same molecular
composition (A-2–A-7) were prepared by radical
degradation of A-1 sample in aqueous solutions, following
the procedure described in . We used technical grade
(puriﬁ ed) aluminum sulfate Al
content 16.35wt %), hydroxoaluminum chloride [Akva-
aurat 30, TU (Technical Speciﬁ cation) 6-09-05-1456–96,
content 30 wt %], pure grade calcium carbonate
with the particle size d
= 0.1 mm, and other chemicals
of chemically pure grade. All solutions were prepared
in distilled water. Sedimentation was performed in
a 150 cm
volumetric cylinder at 20°C. Clariﬁ cation
of the suspension in the cylinder was monitored
continuously by the photosedimentation method
following the procedure similar to that described in .
The content of ionic units in the AA–SA copolymer was
determined by potentiometric titration , and that in
the AA–APTMAC copolymer, mercurimetrically from
the content of chlorides . The molecular weight