Evaluation of different adsorbents for copper removal from cobalt electrolyte
V Yahorava, M Kotze, D Auerswald
Ion exchange is considered to be an effective technology for the removal of
various impurities from cobalt advance electrolytes. With the correct choice
of resin, ion exchange can consistently remove the required impurities to
the levels for the production of high-grade cobalt metal. Although ion
exchange was in the past used primarily for nickel removal, more recently
it has been also considered for the removal of copper, zinc, and cadmium.
Generally, granular ion exchange products are used, but Mintek is currently
evaluating ion exchange fibres for a number of applications, including the
removal of copper from cobalt advance electrolytes. Fibrous ion exchangers
have major advantages compared to granular resins in that they have
significantly higher reaction rates, and wash water volumes could be
limited.
Granular and fibrous ion exchangers were evaluated and compared for
the removal of copper from cobalt advance electrolyte. A synthetic
electrolyte containing 50 g/L cobalt and 50 mg/L copper was used for the
test work. Equilibrium isotherms, mini-column tests, and split elution tests
were done. The results were used to size a full-scale operation to treat
100 m3/h of electrolyte. The potential cobalt losses or recycle requirements
were estimated, and data to calculate indicative operating costs for each
adsorbent was generated. This information was used for a techno-economic
comparison of granular and fibrous ion exchange systems for the removal
of copper from cobalt advance electrolyte.
Keywords: ion exchange, impurity removal, copper, cobalt electrolyte.