Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 1, pp. 1−5.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © V.G. Kazakov, V.A. Lipin, V.A. Matveev, D.V. Maiorov, V.N. Korovin, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86,
No. 1, pp. 3−7.
AND INDUSTRIAL INORGANIC CHEMISTRY
Joint Effect of Parameters of Hydrochemical
Nepheline Processing on Alumina
V. G. Kazakov
, V. A. Lipin
, V. A. Matveev
, D. V. Maiorov
, and V. N. Korovin
St. Petersburg State Technological University of Plant Polymers, St. Petersburg, Russia
St. Petersburg State Polytechnical University, St. Petersburg, Russia
Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw, Kola Scientiﬁ c Center,
Russian Academy of Sciences, Apatity, Russia
Received October 5, 2012
Abstract—A scheme of nepheline processing by a hydrochemical method was technically justiﬁ ed. In this process,
silica is transformed into calcium hydrosilicate under autoclave conditions at a low concentration of caustic alkali.
This allows the process at high heat regeneration and low steam ﬂ ow for evaporation of a solution. A joint effect
of temperature, leaching time, and concentration of caustic alkali solution was examined on an alumina recovery.
Experiments were designed using a combined rotatable design of a second order.
Processing of nepheline concentrate to alumina is
conducted by sintering. This method is characterized
by high energy costs, mainly in the form of fuel in the
charge sintering. Alumina production by this method is
cost-effective only for complex processing of nepheline
concentrate to alumina, soda products, cement, and other
substances [1, 2], so the sintering of high-silicon raw
materials is of limited application.
An alternative way to sintering on nepheline process-
ing to alumina is hydrochemical method (see the scheme)
According to this method nepheline is treated with
an alkaline solution at a temperature above 230°C in the
presence of lime with the transfer of aluminum in a dis-
solved state and the subsequent recovery from a solution
of aluminum hydroxide. Using the hydrochemical pro-
cessing of nepheline allows more than 2 times lowering
energy costs for processing of nepheline to alumina.
However, an industrial implementation of the method is
constrained by the need to use caustic solutions of high
concentrations for processing of raw materials and by
resulting difﬁ culties of hardware design of the process
One version of the hydrochemical method, in which
the concentration of alkali can be reduced to less than
160 g dm
in terms of Na
, consists of the transfer
of silica from nepheline into calcium hydrosilicate by the
·(n – p)H
O + 2(Na,K)AlO
and transfer of aluminum in solution (see the scheme).
In these conditions, the hydrochemical processing the
raw material can be also carried out with a high degree
of heat recovery of an autoclave pulp and the low steam
ow for evaporation of the solution.
The study purpose was to found an optimal combina-
tion of parameters: the concentration of solutions used
for the nepheline decomposition, temperature, leaching
time to achieve the maximum possible recovery of alu-
mina in solution.
In planning the experiment a task was to develop a
dependency, reﬂ ecting the joint effect of temperature,
concentration of caustic alkali in the feedback solution,
and leaching time on the recovery of alumina. For this