1070-4272/01/7411-1868$25.00C2001 MAIK [Nauka/Interperiodica]
Russian Journal of Applied Chemistry, Vol. 74, No. 11, 2001, pp. 1868!1871. Translated from Zhurnal Prikladnoi Khimii, Vol. 74, No. 11,
2001, pp. 1812!1814.
Original Russian Text Copyright + 2001 by Volkov, Svetlov.
PROCESSES AND EQUIPMENT
OF CHEMICAL INDUSTRY
Suspension Separation in a Centrifuge with Biconical Rotor
Yu. P. Volkov and S. A. Svetlov
Biisk Technological Institute, Altai State Technical University, Biisk, Altai krai, Russia
Received June 7, 2001
Abstract-Separation of cellulose nitrate suspensions in a centrifuge with biconical rotor was studied.
An empirical equation was derived, enabling calculation of the efficiency of purification of process water and
wastewater to remove the solid phase in centrifuges of this kind.
At present, sedimentation tanks (wastewater ponds)
are used to purify wastewater to remove polydisperse
solid impurities . These installations have strong
adverse effect on the environment and safety of
humans; their maintenance requires gross expenditure.
At the same time, use of other techniques intensifying
the purification process and, in particular, centrifugal
separation is difficult from both economical and tech-
nological standpoints. This is so because there exist
no sufficiently simple to operate and comparatively
low-cost centrifugal machines with mechanized sedi-
ment discharge and high degree of separation .
Centrifugal apparatus  and centrifuges are
known  in which suspensions are separated in a
rotor comprising two truncated conical cowlings
mounted on a fast-rotating shaft. Preliminary calcula-
tions and experiments on a cylindrical sedimentation
centrifuge demonstrated that the centrifuge with a
biconical rotor must exhibit high efficiency of separa-
tion of finely dispersed and low-concentration suspen-
sions at relatively high centrifugate output capacity.
The aim of this study was to analyze the influence
of basic process parameters (speed of centrifuge rotor
rotation, flow rate and initial concentration of the
starting suspension) on the final concentration of solid
particles in the centrifugate; and to derive empirical
equations for calculating the relative concentration
of the solid phase in the centrifugate, which allows
prognostication of the quality of suspension separation
in centrifuges of the given type.
To perform experimental studies, we designed an
installation comprising a centrifuge 1 and accessory
equipment. A prepared suspension was fed into the
centrifuge from a vessel 2 by means of a centrifugal
pump 3, with the flow rate monitored with rotam-
eter 4, and the speed of shaft rotation, with tachom-
eter 5. The centrifuge power drive allowed variation
of the speed of rotor rotation in the range from 1000
to 6000 rpm.
The centrifuge rotor (Fig. 2) comprised two conical
cowlings, upper 1 and lower 2, and disk 3 pressed to
the lower cowling with a bushing. Apertures through
which the suspension is fed into the centrifuge rotor
were made in the bushing 5. The impermeability of
the cowling junction was ensured by nut 6.
An aqueous suspension of nitrocellulose with solid
particles 1 to 280 mm in size was separated. The
experiments were carried out as follows. A nitrocellu-
lose suspension was poured into the vessel apparatus
and continuously agitated there with blade stirrers,
and a uniform concentration of the solid phase was
maintained in the working volume of the apparatus.
A variable power drive ensured rotor rotation at a
required speed. Then the suspension was fed into the
rotor, and purified liquid was sampled at the centri-
Fig. 1. Schematic of laboratory installation: (1) centrifuge,
(2) apparatus with stirrer, (3) centrifugal pump, (4) rotam-
eter, and (5) tachometer.