Russian Journal of Applied Chemistry, 2013, Vol. 86, No. 9, pp. 1333−1339.
Pleiades Publishing, Ltd., 2013.
Original Russian Text © F.D. Manilevich, L.F. Kozin, B.I. Danil’tsev, 2013, published in Zhurnal Prikladnoi Khimii, 2013, Vol. 86, No. 9, pp. 1362−1368.
AND INDUSTRIAL INORGANIC CHEMISTRY
Improvement of the Efﬁ ciency of Electrochemical
Reﬁ ning of Cobalt
F. D. Manilevich, L. F. Kozin, and B. I. Danil’tsev
Vernadskii Institute of General and Inorganic Chemistry,
National Academy of Sciences of Ukraine, Kiev, Ukraine
Received June 25, 2013
Abstract—To improve the purity of cobalt produced by electrochemical reﬁ ning, the optimal electrolyte composi-
tion and electrolysis mode were determined and a method for diminishing the electrochemical activity of impurity
metals in anodic dissolution of the raw metal and a system for deep puriﬁ cation of the electrolyte solution to
remove impurities were developed. Cathode deposits with a conditional cobalt content exceeding 99.999 wt %,
found in an analysis for the 11 main impurities, were obtained by using the above results in reﬁ ning of K1A cobalt
(≥99.30 wt % Co) in an electrolyzer of distinctive design.
As the technology is developed, the demand for pure
and high-purity cobalt is steadily growing. This metal is
conventionally irreplaceable in manufacture of heavy-
duty precision steels (stainless, heat-resistant, wear-
resistant, tool, and cutting steels), permanent magnets,
and special-purpose catalysts [1, 2]. The advances
in manufacture of high-purity cobalt, made in recent
decades, substantially expanded its application areas.
High-purity cobalt (99.99–99.999 wt % Co) is used, e.g.,
for fabrication of gamma-ray sources, high-temperature
magnets, targets of X-ray tubes, deposition of coatings
and thin ﬁ lms of cobalt and its alloys in memory
devices and other electronic semiconductor devices
and in display panels. At present, nanosize electronic
devices with high-purity cobalt and its alloys are being
intensively developed. High-purity cobalt is a promising
material for metallization of optical waveguides. There
also is purely scientiﬁ c interest in cobalt because of its
properties being close to the intrinsic properties of this
At present, the only economically feasible method
for industrial manufacture of high-purity cobalt
(≥99.99 wt %) is by electrochemical recovery from
thoroughly puriﬁ ed solutions of its salts . The
potential of this method for obtaining high-purity cobalt
are far from being exhausted.
In this communication, we present results of studies
aimed to improve the electrochemical reﬁ ning of cobalt
as a method for obtaining high-purity cobalt.
The efﬁ ciency of the electrolytic puriﬁ cation of
metals is determined by a multitude of factors, from
the electrochemical properties of the main metal and
accompanying impurities to construction materials of the
electrolyzer and production practices. In , processes
occurring in electrochemical reﬁ ning of metals in
aqueous solutions were analyzed and it was shown that
the metal obtained upon a single redeposition contains
nearly all the impurities present in the starting metal,
though in somewhat smaller amount (~1–20%).
The authors of the present study suggested several
procedures substantially diminishing the content of im-
purities in cobalt produced by electrochemical reﬁ ning.
These are the choice of the optimal electrolyte compo-
sition and electrolysis mode, diminishing the electro-
chemical activity of impurity metals in anodic dissolu-
tion of the raw metal, development and application of a
system for continuous thorough puriﬁ cation of the elec-
trolyte solution to remove impurities, and improvement
of the electrolyzer design.