ASET Technology Alberta Fall 2021 - 36

PROJECT
Extractive
Hydrometallurgy for
the Recovery of Cobalt
PROJECT DESCRIPTION
Cobalt is a scarce metal that is becoming increasingly important.
Moreover, cobalt does not occur naturally in its
elemental state; this metal is dispersed in ores containing
nickel as well as sulfides and arsenic. Canada is one
of a dozen countries globally along with Congo and Russia
where it is economically viable to mine and export this raw
material. The global market for cobalt is estimated to grow
to a 14-billion-dollar industry by the year 2027.
Cobalt is a vital component in lithium-ion batteries and this
usage accounts for about 50 per cent of the cobalt produced
globally. With rising demand for renewable energy
and subsequently improvements to the performance of current
energy storage solutions via electricity in batteries, the
availability and the cost-effectiveness of this raw material
will be crucial in the battle against climate change.
Pyrometallurgy is typically used in conjunction with hydrometallurgical
processes. As the name depicts, pyrometallurgy
is an energy-intensive process also referred to as
roasting that heats the mineral up to 700 °C. The roasting
process features reduction, oxidation and sulfation. Afterwards,
hydrometallurgical refining is conducted with many
approaches, such as the Sherritt-Gordon process which
includes ammonia leach followed by hydrogen reduction.
These operations have been subject to scrutiny due to environmental
concerns. Wholly hydrometallurgical processes
such as solvent extraction are gaining attention due to high
extraction efficiency, affordability and sustainability.
The main challenge in the hydrometallurgical recovery of
cobalt is its separation from nickel ions in aqueous media
due to similar physicochemical properties. One approach
is the use of quaternary ammonium salts as an extractant.
Methyltrioctylammonium chloride (MTOAC) is an inexpensive
anion exchanger that will preferentially replace
its inorganic anion for an anionic metal chloride complex.
Tetrachlorocobaltate(II) [CoCl4]2- exhibits good stability in
aqueous solutions while tetrachloronickelate(II) [NiCl4]2does
not. Therefore, separation can be achieved by addressing
the challenge faced in recovery. Finally, the extractant
can be recovered and reused by acidification in
dilute hydrochloric acid. The extraction efficiency of this
method was reported to be 98.32 per cent for cobalt, with a
nickel loss rate of 0.86 per cent.
The goal of this work was to evaluate a literature method
and verify the results presented, identifying the three main
principles centered around this technique: efficiency, affordability
and sustainability. Extraction efficiency was
validated, while the effects of low MTOAC concentration on
efficiency were also investigated to determine affordability.
Attempts were made to regenerate the extractant for sustainability.
ACADEMIC
INSTITUTION
SAIT
ENGINEERING TECHNOLOGY DISCIPLINE
Chemical
36 | FALL 2021 | TECHNOLOGY ALBERTA
ASET Technology Alberta Fall 2021

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