XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2175
alternative wetting liquid that suppressed the dissolution
and only measured the heat of wetting.
CONCLUSION
Calorimetry is a useful method to measure interfacial inter-
actions between a mineral and a reagent (either water or
a collector) in a mineral processing context. It has been
shown in previous reports to be an extremely useful tool in
this regard, but there are challenges to the technique that
should be highlighted.
Isothermal Titration Calorimetry
The isothermal titration technique has proven very useful as
a pre-screening technique in the development of novel col-
lectors. Conventional collector testing is usually done using
either with batch or micro-flotation tests and this is often
time-consuming, uses large quantities of ore that may not
be readily available, and may be costly in terms of assays,
ore transport and disposal. ITC can address the challenge of
high throughput testing alongside computational model-
ing without such time-consuming and costly experiments.
However, a lack of consistent and reliable correlations
between the heat of adsorption and flotation response, as
highlighted by Taguta et al. (2017), has led to improve-
ments in experimental methodologies. The difficulty of
controlling pH within the microcalorimetry ampoule was
identified as a drawback and was subsequently addressed by
performing scale-up experiments external to the calorime-
ter for better pH control. However, in cases where minerals
are scarce and costly, studying the interactions of dissolved
metal salts with collectors provides valuable insights into
the behaviour of a collector. This approach also avoids
the complexities associated with variable mineral surface
properties, oxidation, impurities, and pH variations and
provided a surprisingly consistent correlation between ther-
modynamic parameters and the microflotation recovery of
the metal-containing mineral, albeit on a small sample size.
Comparisons with previous studies, such as those by
McFadzean et al. (2023) and Robledo-Cabrera et al. (2015),
reveal interesting parallels in the relationship between the
heat of formation and the number of carbon atoms in the
alkyl chain. These studies provide insight into the reactive
headgroup interaction with the metal ion in both solution
and on mineral surfaces as the collector carbon chain length
approaches zero.
Immersion Calorimetry
The immersion calorimetry method which measures the
heat evolved when a powdered mineral surface contacts a
liquid (typically water), is directly relevant to flotation, as
it reflects the wettability, or hydrophobicity, of the min-
eral surface—a crucial factor in flotation recovery. Notably,
immersion calorimetry overcomes some limitations of iso-
thermal titration methods, providing a more comprehensive
measure of how mineral surfaces respond to an air-water
interface. It is a useful tool for assessing mineral wettabil-
ity, with demonstrated relevance to flotation performance.
The method’s advantages in terms of accuracy and material
requirements make it a valuable addition to the toolkit for
understanding the complex interactions involved in the flo-
tation process. Ongoing challenges, particularly in dealing
with complex ore compositions, warrant further explora-
tion and refinement of the technique for broader applica-
bility in flotation modeling.
REFERENCES
Douillard, J.M., Zajac, J., Malandrini, H. and Clauss, F.
(2002): Contact Angle and Film Pressure :Study of a
Talc Surface. Journal of Colloid and Interface Science,
255: 341–351.
Goncharuk, O.V. (2015): The heat of immersion of modi-
fied silica in polar and nonpolar liquids. Journal of
Thermal Analysis and Calorimetry, 120: 1365–1373.
Magudu, A. 2022. A methodology for the heat of immer-
sion as a measure of wettability of mineral mixtures.
MSc dissertation, University of Cape Town.
McFadzean, B., Mkhonto, P., Ngoepe, P.E. 2023.
Interactions of xanthates of increasing chain length
with pyrite surfaces: A DFT-D and microcalorimetry
study, Applied Surface Science, 607.
McFadzean, B., Mkhonto, P., Ngoepe, P. 2022. Interactions
of xanthates of increasing chain length with pyrite sur-
faces: A DFT-D and microcalorimetry study. Applied
Surface Science, 607.
McFadzean, B., Moller, K.P. and O’Connor, C.T. 2015. A
thermochemical study of thiol collector surface reac-
tions on galena and chalcopyrite. Minerals Engineering,
83–88.
McFadzean, B. O’Connor, C.T. 2014. A thermochemi-
cal study of thiol collector surface reactions on galena.
Minerals Engineering, 65, 54–60.
Salles, F., Henry, M. and Douillard, J. (2006): Determination
of the surface energy of kaolinite and serpentine using
PACHA formalism—Comparison with immersion
experiments. Journal of Colloid and Interface Science,
303: 617–626.
alternative wetting liquid that suppressed the dissolution
and only measured the heat of wetting.
CONCLUSION
Calorimetry is a useful method to measure interfacial inter-
actions between a mineral and a reagent (either water or
a collector) in a mineral processing context. It has been
shown in previous reports to be an extremely useful tool in
this regard, but there are challenges to the technique that
should be highlighted.
Isothermal Titration Calorimetry
The isothermal titration technique has proven very useful as
a pre-screening technique in the development of novel col-
lectors. Conventional collector testing is usually done using
either with batch or micro-flotation tests and this is often
time-consuming, uses large quantities of ore that may not
be readily available, and may be costly in terms of assays,
ore transport and disposal. ITC can address the challenge of
high throughput testing alongside computational model-
ing without such time-consuming and costly experiments.
However, a lack of consistent and reliable correlations
between the heat of adsorption and flotation response, as
highlighted by Taguta et al. (2017), has led to improve-
ments in experimental methodologies. The difficulty of
controlling pH within the microcalorimetry ampoule was
identified as a drawback and was subsequently addressed by
performing scale-up experiments external to the calorime-
ter for better pH control. However, in cases where minerals
are scarce and costly, studying the interactions of dissolved
metal salts with collectors provides valuable insights into
the behaviour of a collector. This approach also avoids
the complexities associated with variable mineral surface
properties, oxidation, impurities, and pH variations and
provided a surprisingly consistent correlation between ther-
modynamic parameters and the microflotation recovery of
the metal-containing mineral, albeit on a small sample size.
Comparisons with previous studies, such as those by
McFadzean et al. (2023) and Robledo-Cabrera et al. (2015),
reveal interesting parallels in the relationship between the
heat of formation and the number of carbon atoms in the
alkyl chain. These studies provide insight into the reactive
headgroup interaction with the metal ion in both solution
and on mineral surfaces as the collector carbon chain length
approaches zero.
Immersion Calorimetry
The immersion calorimetry method which measures the
heat evolved when a powdered mineral surface contacts a
liquid (typically water), is directly relevant to flotation, as
it reflects the wettability, or hydrophobicity, of the min-
eral surface—a crucial factor in flotation recovery. Notably,
immersion calorimetry overcomes some limitations of iso-
thermal titration methods, providing a more comprehensive
measure of how mineral surfaces respond to an air-water
interface. It is a useful tool for assessing mineral wettabil-
ity, with demonstrated relevance to flotation performance.
The method’s advantages in terms of accuracy and material
requirements make it a valuable addition to the toolkit for
understanding the complex interactions involved in the flo-
tation process. Ongoing challenges, particularly in dealing
with complex ore compositions, warrant further explora-
tion and refinement of the technique for broader applica-
bility in flotation modeling.
REFERENCES
Douillard, J.M., Zajac, J., Malandrini, H. and Clauss, F.
(2002): Contact Angle and Film Pressure :Study of a
Talc Surface. Journal of Colloid and Interface Science,
255: 341–351.
Goncharuk, O.V. (2015): The heat of immersion of modi-
fied silica in polar and nonpolar liquids. Journal of
Thermal Analysis and Calorimetry, 120: 1365–1373.
Magudu, A. 2022. A methodology for the heat of immer-
sion as a measure of wettability of mineral mixtures.
MSc dissertation, University of Cape Town.
McFadzean, B., Mkhonto, P., Ngoepe, P.E. 2023.
Interactions of xanthates of increasing chain length
with pyrite surfaces: A DFT-D and microcalorimetry
study, Applied Surface Science, 607.
McFadzean, B., Mkhonto, P., Ngoepe, P. 2022. Interactions
of xanthates of increasing chain length with pyrite sur-
faces: A DFT-D and microcalorimetry study. Applied
Surface Science, 607.
McFadzean, B., Moller, K.P. and O’Connor, C.T. 2015. A
thermochemical study of thiol collector surface reac-
tions on galena and chalcopyrite. Minerals Engineering,
83–88.
McFadzean, B. O’Connor, C.T. 2014. A thermochemi-
cal study of thiol collector surface reactions on galena.
Minerals Engineering, 65, 54–60.
Salles, F., Henry, M. and Douillard, J. (2006): Determination
of the surface energy of kaolinite and serpentine using
PACHA formalism—Comparison with immersion
experiments. Journal of Colloid and Interface Science,
303: 617–626.