ISSN 1070-4272, Russian Journal of Applied Chemistry, 2007, Vol. 80, No. 9, pp. 1491!1497. + Pleiades Publishing, Ltd., 2007.
Original Russian Text + V.A. Lebedev, V.I. Sal’nikov, M.V. Tarabaev, I.A. Sizikov, D.A. Rymkevich, 2007, published in Zhurnal Prikladnoi Khimii, 2007,
Vol. 80, No. 9, pp. 1455!1461.
AND CORROSION PROTECTION OF METALS
Compatibility of TiO
with a CaO!CaCl
V. A. Lebedev, V. I. Sal’nikov, M. V. Tarabaev, I. A. Sizikov, and D. A. Rymkevich
Ural State Technical University, State Educational Institution for Higher Professional Education,
AVISMA Titanium and Magnesium Combine, Open Joint-Stock Company, Berezniki, Perm krai, Russia
Received September 16, 2006; in final form, February 2007
Abstract-Interaction of TiO
with a CaO!CaCl
melt was studied to determine whether electrolytic produc-
tion of titanium from oxide raw materials is possible.
Titanium is among the most widely occurring met-
als and possesses a unique combination of properties.
Its wide and efficient use in various fields of national
economy is hindered by the high cost of the metal,
which is due to the multistage and batch nature of
the Kroll process employed in modern titanium in-
dustry. Numerous attempts to develop a continuous
electrolytic technique for manufacture of titanium
from titanium tetrachloride have failed to produce
a widely used industrial technique because of the dif-
ficulties associated with the polyvalent nature of
the metal, its high vapor pressure, and susceptibility
of the tetrachloride to hydrolysis.
In recent years, a considerable interest has been ob-
served in the possibility of electrolytic production of
titanium from oxide raw materials. It has been found
that understoichiometric titanium dioxide has high
electrical conductivity and can serve as a cathode both
in reduction of titanium oxides to the metal and in
removal of dissolved oxygen from titanium.
It was suggested by Chen et al. [1, 2] to perform
direct electrochemical reduction of TiO
in molten CaCl
, which is the so-called FFC process.
It was shown on laboratory scale that the reduction
reaction occurs at 950oC on a cathode made of solid
, with oxygen anions oxidized on a graphite
anode to give CO
. Pure calcium chloride CaCl
chosen as a molten salt electrode because of the high
solubility of calcium oxide in this compound.
Ono and Suzuki  studied the high-temperature
calcium reduction of TiO
and developed a process
for continuous production of titanium. The electroly-
sis was performed at a voltage that was higher than
the decomposition voltage of CaO, but lower than that
ions were reduced at the cathode to
Ca; oxygen evolved at the anode reacted with carbon
to give CO and CO
. A cell for continuous manufac-
ture of titanium was developed and the possibility
of using inert anode was discussed.
In , a TiO
powder or a preform was placed in
a holder, and a Ca + 18 wt % Ni alloy, onto the elec-
trolyzer bottom. The reduction was carried out with-
out a current, with the electrochemical circuit formed
between the TiO
cathode and the calcium alloy. In
the process, TiO
was reduced and calcium ions were
deposited at the anode. The alloy was replenished
with calcium at regular intervals of time.
It seems that the FFC process is the best developed
and ready for implementation [1, 2, 5, 6].
In view of the possible use of CaO as the main
component in electrolytic reduction of TiO
necessary to substantiate the optimal CaO content and
to analyze the oxidation kinetics of O
ions in rela-
tion to temperature and CaO concentration. It remains
unclear whether TiO
is compatible with the CaCl
The rich experience of the electrometallurgy of
aluminum indicates that the main reason for a de-
crease in the current efficiency is the reverse reaction
of the electrolysis products (aluminum and CO
which may lead to contamination of the metal by car-
bon via formation of carbides. This issue has not been
studied for the materials under consideration. Possibly,
it is necessary to choose a stable porous diaphragm for
separating the cathode and anode spaces in electroly-
sis. The aim of this study was to elucidate these