2169
Heat of the Matter: Application of Microcalorimetry
in Evaluating Interfacial Chemistry for Enhanced
Flotation Efficiency
B. McFadzean, A. Magudu, S. Geldenhuysa C.T. O’Connor
Centre for Minerals Research
T.M. Thiart, D.W. Gammon
Chemistry Department, University of Cape Town, South Africa
ABSTRACT: Calorimetry is the process of measuring the heat exchange during chemical reactions. This
paper highlights the strengths and weaknesses of using highly sensitive microcalorimetry in studying mineral
interfacial interactions. Thermodynamic parameters were measured and used to rank the strength of interaction
of various collector-metal complexes, using isothermal titration calorimetry. This analysis was then extended to
collector-mineral interfaces and subsequently to flotation recoveries. Immersion calorimetry, on the other hand,
was used to evaluate mineral surface wettability. The practical implications of these techniques are highlighted as
pre-screening tools for novel reagent design and wettability parameters in flotation modelling and optimization.
INTRODUCTION
Calorimetry has received relatively little attention in mineral
processing applications. Nevertheless, it is ideally suited to
the investigation of thermodynamic interactions at mineral
interfaces, which is fundamental to the flotation process. It
is able to investigate sub-monolayer dosage of reagents in
real time in a realistic slurry environment (McFadzean and
O’Connor, 2014 McFadzean et al., 2015), as well as deter-
mine wettabilities of mineral surfaces both pre and post col-
lector treatment (Taguta et al., 2018). However, there are
drawbacks to the technique which should be considered.
Both the advantages and disadvantages of the technique
will be explored in this paper.
Calorimetry covers many types of heat transfer phe-
nomena. The two that are most applicable to a flotation
application, and which will be discussed in this paper, are
isothermal titration calorimetry and immersion calorim-
etry. In the first, a reagent such as a collector is titrated into
a mineral slurry and the heat evolved is measured. In the
second technique, the enthalpy of the interaction between a
dry mineral powder and a liquid (usually water) is measured.
The greater the interaction, the more polar and, therefore,
more wettable the mineral surface. This technique can also
be used to determine the surface energy of a mineral when
at least three different wetting liquids are used. When water
is used as the wetting fluid this technique is essentially mea-
suring the hydrophobicity or hydrophilicity of a mineral.
Both techniques have been extensively used by the authors
over the last decade and this paper addresses many of the
issues investigated during that time.
Heat of the Matter: Application of Microcalorimetry
in Evaluating Interfacial Chemistry for Enhanced
Flotation Efficiency
B. McFadzean, A. Magudu, S. Geldenhuysa C.T. O’Connor
Centre for Minerals Research
T.M. Thiart, D.W. Gammon
Chemistry Department, University of Cape Town, South Africa
ABSTRACT: Calorimetry is the process of measuring the heat exchange during chemical reactions. This
paper highlights the strengths and weaknesses of using highly sensitive microcalorimetry in studying mineral
interfacial interactions. Thermodynamic parameters were measured and used to rank the strength of interaction
of various collector-metal complexes, using isothermal titration calorimetry. This analysis was then extended to
collector-mineral interfaces and subsequently to flotation recoveries. Immersion calorimetry, on the other hand,
was used to evaluate mineral surface wettability. The practical implications of these techniques are highlighted as
pre-screening tools for novel reagent design and wettability parameters in flotation modelling and optimization.
INTRODUCTION
Calorimetry has received relatively little attention in mineral
processing applications. Nevertheless, it is ideally suited to
the investigation of thermodynamic interactions at mineral
interfaces, which is fundamental to the flotation process. It
is able to investigate sub-monolayer dosage of reagents in
real time in a realistic slurry environment (McFadzean and
O’Connor, 2014 McFadzean et al., 2015), as well as deter-
mine wettabilities of mineral surfaces both pre and post col-
lector treatment (Taguta et al., 2018). However, there are
drawbacks to the technique which should be considered.
Both the advantages and disadvantages of the technique
will be explored in this paper.
Calorimetry covers many types of heat transfer phe-
nomena. The two that are most applicable to a flotation
application, and which will be discussed in this paper, are
isothermal titration calorimetry and immersion calorim-
etry. In the first, a reagent such as a collector is titrated into
a mineral slurry and the heat evolved is measured. In the
second technique, the enthalpy of the interaction between a
dry mineral powder and a liquid (usually water) is measured.
The greater the interaction, the more polar and, therefore,
more wettable the mineral surface. This technique can also
be used to determine the surface energy of a mineral when
at least three different wetting liquids are used. When water
is used as the wetting fluid this technique is essentially mea-
suring the hydrophobicity or hydrophilicity of a mineral.
Both techniques have been extensively used by the authors
over the last decade and this paper addresses many of the
issues investigated during that time.