ISSN 1070-4272, Russian Journal of Applied Chemistry, 2006, Vol. 79, No. 10, pp. 1729!1730. + Pleiades Publishing, Inc., 2006.
Original Russian Text + G.A. Mandrov, M.Yu. Klimovich, A.N. Pukh, 2006, published in Zhurnal Prikladnoi Khimii, 2006, Vol. 79, No. 10,
Clarification of Coal-Clay Disperse Systems
with Modified Polyacrylamide Flocculant
G. A. Mandrov, M. Yu. Klimovich, and A. N. Pukh
Institute of Coal and Coal Fuel Chemistry, Siberian Division, Russian Academy of Sciences, Kemerovo, Russia
Kemerovo Branch, Institute of Chemistry of Solids and Mechanochemistry, Siberian Division,
Russian Academy of Sciences, Kemerovo, Russia
Received February 10, 2006
Abstract-Modification of polyacrylamide under mild conditions was studied.
Wastes from ore dressing enterprises, concentrated
in sludge precipitation tanks of various designs and
in sludge ponds, occupy large fields and pollute sur-
face and underground waters and open reservoirs.
From the safety viewpoint, processing of finely dis-
persed coal sludge from sludge ponds and precipita-
tion tanks should improve the environmental situation
around ore dressing enterprises.
One of the key problems of flotation is precipitation
of fine (smaller than 30 mm) particles, which pass, in
the case of modern processing procedures, into the fi-
nal tailings with the mineral component. Owing to
the absence of inexpensive and efficient reagents for
concentration of coal fines by flotation, low-ash wastes
are discharged into precipitation tanks, which causes
of additional loss of the coal combustible mass.
In this study, we examined the possibility of en-
hancing the flocculation activity of domestic poly-
acrylamide (PAA), which is the most widely used floc-
culant with a well-developed production technology.
A large number of parameters that affect the struc-
ture formation in the course of polymer modification
should be taken into account. Because of this circum-
stance, preparation of modified PAA with specified
flocculation properties by the reaction of PAA with
reactive monomers is a rather difficult problem. These
parameters include the type and distribution of charged
groups in the polymer chain, chain length, charge
density, degree of branching and microstructure of
macromolecules, polymer-monomer molar ratio, pH
of the medium, temperature, pressure, etc. .
Taking into account the above factors, we chose
the modification pathway making the structure more
branched. PAA was modified with a-propylene chloro-
hydrin (1-chloro-2-propanol). The reaction of the ini-
tial PAA (molecular weight 1 0 10
) with the above re-
agent was performed by the procedure reported in .
The resulting modified polyacrylamide (MPAA) was
tested in clarification of coal-clay disperse systems. For
these purpose, we used coal sludges from the sludge
dump of the processing plant, which contains a mix-
ture of coking coals of K, KO, and KS brands. These
sludges were preliminarily concentrated using a hydro-
sizer . The hydrosizer allows preparation of an en-
riched coal concentrate with permissible ash content and
increased ash content in the rock material. After treat-
ment of the coal suspension with the initial ash content
= 32.5% in the hydrosizer, we obtained a concen-
trate with ash content A
=10311%. Then, the coal-
clay suspension was treated with a flocculant. The ini-
tial coal sludge was sieved (mesh size 800 mm), and,
after treatment in the hydrosizer, we obtained a coal-
clay suspension with a mean geometrical diameter of
particles of the dispersed phase of 2.25 mm (Fig. 1).
Fig. 1. Particle size distribution of the coal-clay suspension.
(d) Particle diameter and (A) number of particles.