INNOVATIVE PROCESS FOR ACTINIDE AND RARE EARTH ELEMENTS RECOVERY
FROM NUCLEAR WASTES, MINE WASTES AND ORE CONCENTRATE
REYNIER N.1,*, LASTRA R.1, LAVIOLETTE C.1, FISET J.F.1, BOUZOUBAÂ N.1, CHAPMAN M2.
1
CanmetMINING, Natural Resources Canada, 3484 Limebank Rd., Ottawa, ON, Canada K1A 0E4
Canadian Nuclear Laboratories, Chalk River Laboratories, Plant Road, Chalk River, ON KOJ 1JO
* Contact information, E-Mail: nicolas.reynier@canada.ca, Tel.: +1-613-954-5602
2
Canadian Nuclear Laboratories (CNL) is developing disposal strategy for radioactive wastes, which
contains significant amounts of uranium, cesium, and mercury. There are safety and economic incentives
for the extraction of these elements before permanent storage in deep underground repositories. In addition,
the actinide elements are also an important component in rare earth elements (REE) ores and considered as
impurities. Actinides separation from REE tailings is a big concern in order to manage radioactive
nuclides. Reprocessing mine wastes may present significant financial and environmental benefits.
Experiments were carried out with radioactive cemented wastes (RCW) prepared at CanmetMINING. For
all the tested RCW batches, solubilisation yields are above 97% for Cs and 98% for U and Hg. Sulfuric
acid leaching with potassium iodide improved the solubilisation by oxidation and forming tetraiodide
complex (e.g. HgI42-, Kf = 2.1030). Cs and Hg were removed selectively by using potassium cobalt
hexacyanoferrate (KCFC) and resin Lewatit TP214 respectively. U recovery using the chelating resin
Lewatit TP260 was the most efficient. The presence of high iodine concentration improved the U uptake
by the resin. The best U stripping was obtained using 1M Na2CO3, which allows 99% of U recovery. U
was then precipitated as sodium diuranate. A counter current effluent recirculation was performed
successfully on RCW. The process was also applied to submerged tailings collected from two U mines and
an REE ore concentrate. This paper presents an innovative process, using sulfuric acid and potassium
iodide, for U, Cs, and Hg recovery from nuclear wastes as well as for REE, U, and Th recovery from mine
wastes and ore concentrate. Outcomes of this research are the development of innovative technologies for
radioactive wastes management and for helping the mining industries to enhance purification of REE by
the separation of radioactive impurities.
Figure 1 – REE, U, and Th solubilization from an ore concentrate and radioactive mine wastes using
sulfuric acid and potassium iodide (t = 120 min, H2SO4 = 2M, PD = 10%, T = 20°C, KI = 0.6M).
Figure 2 – Optical microscope photograph and EDS spectrum of the sodium diuranate obtained by the U
recovery in sulfuric and iodide media and precipitation using sodium hydroxide.
KEYWORDS
Nuclear waste, Mine waste, Rare Earth Elements, Uranium, Iodide, Sulfuric acid, Leaching, Ion exchange