Journal article

Adsorption of copper sulphate on PGM-bearing ores and its influence on froth stability and flotation kinetics

Research Areas

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Publication Details

Author list: Nyabeze W, McFadzean B

Publisher: Elsevier

Publication year: 2016

Journal: Minerals Engineering

Journal name: Minerals Engineering

Volume number: 92

Start page: 28

End page: 36

Total number of pages: 9

ISSN: 0892-6875



Copper sulphate is used as an activator in the flotation of base metal
sulphides as it promotes the interaction of collector molecules with
mineral surfaces. It has been used as an activator in certain platinum
group mineral (PGM) flotation operations in South Africa although the
mechanisms by which improvements in flotation performance are achieved
are not well understood. Some investigations have suggested these
changes in flotation performance are due to changes in the froth phase
rather than activation of minerals by true flotation in the pulp zone.
In the present study, the effect of copper sulphate on froth stability
was investigated on two PGM containing ores, namely Merensky and UG2
(Upper Group 2) ores from the Bushveld Complex of South Africa. Froth
stability tests were conducted using a non-overflowing froth stability
column. Zeta potential tests and ethylenediaminetetraacetic acid (EDTA)
tests were used to confirm the adsorption of reagents onto pure minerals
commonly found in the two ores. The results of full-scale UG2
concentrator on/off copper sulphate tests are also presented. The UG2
ore showed a substantial decrease in froth stability in the order of
reagent addition: no reagents > copper > xanthate > copper +
xanthate, while Merensky ore showed a slight decrease. It was shown
through zeta potential measurements that copper species were to be found
on plagioclase, chromite, talc and pyrrhotite surfaces and through EDTA
extraction that this copper was in the form of almost equal amounts of
Cu(OH)2 and chemically reacted copper ions on the Merensky
and UG2 ore surfaces. In certain cases, the presence of copper sulphate
and xanthate substantially increased the recovery, and therefore the
implied hydrophobicity, of pure minerals in a frothless microflotation
device. It was, therefore, proposed that increases in hydrophobicity
beyond an optimum contact angle for froth stability, were the cause of
instabilities in the froth phase and these were found to impact grade
and recovery in a full-scale concentrator. Differences in the extent of
froth phase effects between the different ores can be attributed to
differences in mineralogy.


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