INORGANIC SYNTHESIS AND INDUSTRIAL
Russian Journal of Applied Chemistry, 2011, Vol. 84, No. 9, pp. 1476−1482.
Pleiades Publishing, Ltd., 2011.
Original Russian Text © D.E. Chirkst, O.L. Lobacheva, N.V. Dzhevaga, 2011, published in Zhurnal Prikladnoi Khimii, 2011, Vol. 84, No. 9, pp. 1424−1430.
Ion Flotation of Rare-Earth Metals
with Sodium Dodecyl Sulfate
D. E. Chirkst, O. L. Lobacheva, and N. V. Dzhevaga
St. Petersburg State Mining Institute, St. Petersburg, Russia
Received October 27, 2010
Abstract—Ion ﬂ otation of rare-earth metals with sodium dodecyl sulfate and the effect of chloride ions on this
process were studied. Values of the distribution coefﬁ cients were obtained.
Rare-earth metals (REMs) and their compounds
become increasingly important for modern technology.
Large amounts of REMs are used in the form of a mixture
of oxides in metallurgical, glass-making, and ceramic
industries. Cerium, neodymium, samarium, europium,
and gadolinium are most widely used as compounds
of individual REMs. Cerium oxide is applied in glass
and mirror polishing. The misch metal containing 50%
cerium, 30% lanthanum, 15% neodymium, and 5%
praseodymium has found wide use. This alloy serves to
purify steel by removal of free oxygen and sulfur and
admixtures of lead and antimony.
Individual REMs are in the highest demand in the
world market. In Russia, the main source of rare-metal
raw materials are loparite ores from the Lovozero
deposit [1, 2]. Therefore, it is necessary to develop
a technology for production of a wide assortment of
individual rare-earth elements. A promising way is to use
the ﬂ otation technique, which can produce a concentrate
with 60–70% REM oxides. The ion ﬂ otation is a process
in which ions present in solution are recovered with
ionogenic surfactants serving as collecting agents .
To perform ion ﬂ otation, gas bubbles and a collecting
agent are introduced into the starting solution. The
collecting agent forms in solution surface-active ions
whose charge is opposite in sign to that of the ion being
recovered. A compound of surface-active and recovered
ions is concentrated on the surface of gas bubbles and is
carried by these bubbles to the foam.
It has been found previously  that, in extraction
of REMs with tributyl phosphate (TBP) from nitrate
solutions, the distribution coefﬁ cients vary within the
range 1.1–1.4. No large distribution coefﬁ cients were
observed in ion ﬂ otation of REMs, either . It was
noted in  that addition of chlorides in concentrations
of 0.1–0.15 M makes lower the distribution coefﬁ cient
in extraction with naphthenic acid due to formation
of unextractable chloro complexes. Because of the
different stabilities of the chloro complexes, this
lowering varies and, consequently, the Ce/Y separation
coefﬁ cient increases from 1.5 to 14. A method has been
developed for raising the separation coefﬁ cient of REMs
by changing the anionic composition of the aqueous
phase . Therefore, it is of interest to study the effect
of chloride ions on the ion ﬂ otation process.
We performed ﬂ otation in a 137 V-FL laboratory
ﬂ otation machine with a 1-dm
cell in the course of 5 min.
As model solutions served 0.001 M solutions of cerium,
samarium, europium, yttrium, or ytterbium nitrates. The
solution volume was 200 ml. Dry sodium dodecyl sulfate
(NaDS) was added as a surfactant to a concentration of
0.003 M. We also added sodium chloride to the starting
solution in amounts corresponding to concentrations of
0.01 and 0.05 M. At a NaCl concentration of 0.1 M, the
ﬂ otation of lanthanides is nearly fully suppressed. The
resulting foam and chamber products were separated
and analyzed. The foam was disintegrated with 1 M
sulfuric acid. The REM concentration was determined