Laureate Professor University of South Australia
September 6, 2016 2:00 pm
8-207 Donadeo Innovation Centre for Engineering
Surface Chemistry- Inorganic and Organic Tailoring of Mineral Interfaces for
Inorganic and organic reagents can selectively alter the surfaces of
metal oxide and metal sulfide surfaces. The basic ideas and concepts of the interaction of inorganic
and organic reagents with mineral surfaces, along with their subsequent
influence on dispersion stability are explored.
We classify mineral surfaces according to their surface
charge and intrinsic hydrophobicity, illustrating how techniques ranging from
wettability determinations and surface spectroscopy to atomic force microscopy
and rheology may be used as classification tools.
Metal oxide surfaces develop surface charge and potential, as
do metal sulphides. However the latter also respond to oxidation-reduction
potential and, upon exposure to an aqueous environment, their surface chemistry
changes with time. pH, the presence of dissolved oxygen, the influence of
sulfoxy species, low MW xanthates, sulphide ions, cyanide and metal ion hydrolysis products can all
have a significant influence on the surface chemistry and separation behaviour
of metal sulphides. We reveal how
knowledge of the surface chemistry can be used to achieve exquisite
The surface chemistry of metal oxide and silicate surfaces
may be manipulated by pH and the presence of low and high MW reagents. We focus
on high MW organic reagents in this lecture, illustrating the mechanisms by
which they interact with mineral surfaces, coupled to a thermodynamic summary.
Application of these concepts to the control of talc
wettability through the adsorption of specific polymers is dealt with,
including considerations of adsorbed layer density, morphology, contact angle
measurements and underlying solid surface structure. For kaolinite, we place
particular emphasis on the importance of temperature in flocculation. Adsorbed
layer thickness, electrokinetic potential, hydrodynamic diameter, yield stress,
separation energy and ‘goodness of solvent’ are all shown to play a major role
in the ability to build compact floc structures and efficient flocculation.