chemistry 4
C H E M I S T R Y
mised risk exposure, and the facilitation of research aimed at exploiting the inherent
reaching compliance to the requirements catalytic properties of the platinum group
of the International Cyanide Management of metals and culminating in the Mintek/
Code. DST Nanotechnology Innovation Centre,
an initiative of DST, which was launched in
The programme, Project AuTEK, was initi- November 2007.
ated in 2000 as a joint research venture be-
tween Mintek and the three major South The biomedical programme focuses on
African producers of gold, with the aim the discovery of new types of gold-based
of developing new industrial uses of the biomedical agents with emphasis on HIV/
metal. The programme has three focus ar- AIDS, cancer and malaria. Relatively re-
eas, catalysis (co-sponsored by AngloGold cently, a strategic decision was taken to
Ashanti), nanotechnology (co-sponsored focus internally on HIV, with the cancer
by Gold Fields) and biomedical applica- and malaria research programmes being
tions (co-funded by Harmony Gold). continued at the universities, but still be-
ing directed by Mintek.
The first target was the development of a
catalyst for the oxidation of CO to CO
2
at Early research at Mintek on flotation, an
room temperatures. Gold particles with important and relatively widely used tech-
diameters in the range 4-10 nm dispersed nique for the separation and recovery of
on the surface of inert oxide substrates a particular valuable mineral from an as-
proved very useful in this context. The key semblage of unwanted waste minerals, fo-
to the success of this venture was the de- cused on the development of small-scale
velopment of the necessary conditions for flotation devices to understand how the
the precipitation of hydrated gold oxides surface properties of minerals are influ-
on the oxide surface to achieve eventu- enced by chemical additives, and how this
ally a uniform and well-dispersed pre- affects the flotation of a range of minerals.
cipitation of gold particles of the correct Later research was directed towards the
diameter. The research has resulted in the identification of appropriate collectors, de-
construction of a semi-commercial plant pressants, and frothers for local ores. Major
for producing sufficient quantities of the developments have included an under-
catalyst, marketed under the trade name standing on how the adsorption and de-
AUROlite
TM
, for prototype evaluation by sorption of chemical species to-and-from
potential clients. Gold catalysts have also the mineral surfaces of prepared mixtures
been developed for chemical process re- of fluorite, apatite, and calcite controls the
actions such as epoxidation and selective separation of fluorite and apatite from cal-
hydrogenation. cite, a knowledge of the mechanism of talc
depression by polysaccharide-based rea-
The principles of nanoscience and nano- gents as applied to the separation of this
technology that were developed during mineral from base-metal sulfide minerals
this project have since been extended into and the activation of sulphide and gangue
127
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