PRODUCTION AND EQUIPMENT
CAPTURING NANOPARTICLES IN ALUMINA PRODUCTION
S. Ya. Davydov,
R. A. Apakashev,
and V. N. Koryukov
Translated from Novye Ogneupory, No. 2, pp. 12 – 15, February, 2016.
Original article submitted November 24, 2015.
The movement of charged dust particles of different sizes in an electrostatic precipitator is studied. It is found
that such particles acquire different velocities before they are deposited in the precipitator. They differ signifi
cantly from one another in the curvature of their trajectories, which makes it easier to precipitate nanoparticles
from the general dust-air flow. A unit is proposed for capturing the nanosized fraction of dust particles in the
upward pneumatic transport of bulk materials during alumina production.
Keywords: alumina production, bulk materials, upward pneumatic transport, nanosized fraction of particles,
capture, removable inserts, Coulomb forces, electrodes.
The use of nanoparticles as modifying (doping) additives
and as independent materials is creating new opportunities
for the use of familiar substances. For example, the use of
nanoparticles is the only way to obtain a unique set of func-
tional properties in the creation of dispersion-hardened re-
fractory composites. Detailed studies  have shown that ad-
ditions of ceramic nanoparticles have a substantial effect on
the properties of hard alloys WC–Co, WC–TiC–Co, and
TiC–Ni–Mo. It was determined that modification with
nanoparticles improves the durability of the alloys by a
factor of 1.3 – 4.0, improves wear resistance by a factor of
1.6 – 2.0, increases crack resistance by a factor of 1.8 – 2.0,
and elevates flexural strength 25 – 50%. Alumina
nanoparticles are also in demand as an abrasive material, be
ing capable of imparting a high-quality decorative finish to
stone surfaces . However, nanopowders have yet to come
into wide use due to their production cost.
For example, one of the stages in the production of tech
nical alumina is the use of drum-type rotary furnaces to cal
cine aluminum hydroxide precipitated from aluminate solu
tions. The dispersity of the material is increased significantly
by the calcining operation, and a large amount of nanosized
alumina dust is formed inside the furnace. Particles of the
dust are carried out of the furnace by the flue gases and cap-
tured in electrostatic precipitators [3, 4].
It should be noted that nanosized dust is formed during
the occurrence of various processes in furnaces used for cal-
cining. For example, dead-burned lime is obtained at the
Serov Ferroalloys Plant in three rotary furnaces [5, 6].
Studies of the flue-gas tract of the furnaces have shown
that the size of most of the dust particles ranges within
50 – 300 nm.
The nanoparticle of dust formed in calcining furnaces are
usually round in form [5, 7]. The particles are charged by
two mechanisms during the corona discharge in an electro
static precipitator: the action of the electric field (the parti
cles are bombarded by ions moving in the directions of the
field’s lines of force); ion diffusion. The first mechanism is
dominant when the particles are larger than 0.5 mm, while the
second mechanism is dominant when the particles are
smaller than 0.2 mm. Both mechanisms are operative for par
ticles in the diameter range 0.2 – 0.5 mm .
The particles acquire a charge of one sign from the co
rona discharge. The maximum charge is reached in fractions
of a second. The charged particles migrate to and are depos
ited on the discharge electrodes under the influence of the
electric field, giving up their charge to the electrodes in the
Refractories and Industrial Ceramics Vol. 57, No. 1, May, 2016
1083-4877/16/05701-0009 © 2016 Springer Science+Business Media New York
Ural State Mining University, Ekaterinburg, Russia
Ural Federal University, Ekaterinburg, Russia.