152 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Safely dispose of
potentially harmful
elements
Harmful elements are extracted
and can be removed or
concentrated for further processing
using precipitation or other
technologies
Decrease activation energy The addition of synergistic
reagents lowers activation energy
to allow processing at ambient
temperatures.
Electrify processes
wherever possible
This aspect is comparable to other
lixiviant systems (i.e., no better or
worse). E.g., direct electrowinning
of copper is possible from alkaline
glycine leachates.
Use benign chemicals Glycine is an extremely benign
reagent that is used in human
foods or animal feed.
Reduce chemical diversity Cyanide chemistry leads to a
diverse range of species such as
cyanate, thiocyanate, free cyanide,
ferrocyanide, and a diverse range
of WAD cyanides, of which there
are 4 examples for copper only.
Alkaline glycine leaching has a
much smaller number of complex
species, thereby simplifying the
process chemistry.
Implement real-time
analysis and digital
process control
The UV-visible measurement
of base metal complexes, and
the HPLC measurement of
free glycine allows simple
determination of glycinates
in the system. Otherwise, the
measurement and control are
comparable to conventional
leaching processes. Sampling and
measurement are simplified by the
atmospheric pressure and relatively
mild temperatures of the system.
Combine circular
hydrometallurgy with
zero-waste mining
The use of alkaline glycine enables
the deployment of the leach
system in in-situ and in-place
underground leach systems, or
the leaching of existing tailing
impoundments, while removing
the heavy metal content.
Developing new lixiviant technologies requires a holistic
approach covering a multitude of functional requirements,
most of these relating to the overall process circuit, rather
than the leaching stage itself, where metals recovery from
leachates, reagent recovery and reuse, interaction with the
environment, controllability, safety and health, by-product
removal and valorization, water recovery and recycle and
waste disposal have to be attended to, while maintaining a
process that delivers acceptable recoveries within acceptable
capital and operating cost constraints. In gold and precious
metals processing, cyanide originally become a much envi-
ronmentally friendlier (and safer, despite its toxicity) alter-
native to mercury and caused a revolution in the industry at
the turn of the 20th century. We may be at such a turning
point again with yet another alternative lixiviant.
REFERENCES
Aylmore, M., Eksteen, J.J., Wells, M., Jones, M., 2019.
The mineralogy and processing potential of the
Commonwealth project in the Molong Volcanic Belt,
central eastern New South Wales, Australia, Australia.
Ore Geology Reviews. 111, 102976, 30 p.
Bezuidenhout, G.A., Eksteen, J.J., Akdogan, G. Van Beek,
B., Wendt, W. Persson, W., 2017. Implementation of
flame optical emission spectroscopy system for con-
verter Fe end-point control associated with Ni-Cu-S-
PGM converter mattes. Minerals Engineering, 100,
132–143.
Binnemans, K., Jones, P.T., 2023a. The Twelve Principles
of Circular Hydrometallurgy. Journal of Sustainable
Metallurgy, 9, 1–25.
Binnemans, K., Jones, P.T., 2023b. Ionic Liquids and
Deep‑Eutectic Solvents in Extractive Metallurgy:.
Mismatch Between Academic Research and Industrial
Applicability. Journal of Sustainable Metallurgy, 9,
423–438.
Cabri, L.J., Wilhelmij, H.R., Eksteen, J.J., 2017.
Contrasting mineralogical and processing potential of
two mineralization types in the platinum group ele-
ment and Ni-bearing Kapalagulu Intrusion, western
Tanzania. Ore Geology Reviews, 90, 772–789.
Corbett, M.K., Eksteen, J.J., Niu, X.-Z., Watkin, E.L.J.,
2017a. Incorporation of indigenous microorganisms
increases leaching rates of rare earth elements from
Western Australian monazite. Solid State Phenomena,
262 SSP, 294–298.
Corbett, M.K., Eksteen, J.J., Niu, X-Z, Croue, J.P.,
Watkin, E.L.J., 2017b. Interactions of phosphate solu-
bilising microorganisms with natural rare-earth phos-
phate minerals: a study utilizing Western Australian
monazite. Bioprocess and Biosystems Engineering, 40,
929–942.
Safely dispose of
potentially harmful
elements
Harmful elements are extracted
and can be removed or
concentrated for further processing
using precipitation or other
technologies
Decrease activation energy The addition of synergistic
reagents lowers activation energy
to allow processing at ambient
temperatures.
Electrify processes
wherever possible
This aspect is comparable to other
lixiviant systems (i.e., no better or
worse). E.g., direct electrowinning
of copper is possible from alkaline
glycine leachates.
Use benign chemicals Glycine is an extremely benign
reagent that is used in human
foods or animal feed.
Reduce chemical diversity Cyanide chemistry leads to a
diverse range of species such as
cyanate, thiocyanate, free cyanide,
ferrocyanide, and a diverse range
of WAD cyanides, of which there
are 4 examples for copper only.
Alkaline glycine leaching has a
much smaller number of complex
species, thereby simplifying the
process chemistry.
Implement real-time
analysis and digital
process control
The UV-visible measurement
of base metal complexes, and
the HPLC measurement of
free glycine allows simple
determination of glycinates
in the system. Otherwise, the
measurement and control are
comparable to conventional
leaching processes. Sampling and
measurement are simplified by the
atmospheric pressure and relatively
mild temperatures of the system.
Combine circular
hydrometallurgy with
zero-waste mining
The use of alkaline glycine enables
the deployment of the leach
system in in-situ and in-place
underground leach systems, or
the leaching of existing tailing
impoundments, while removing
the heavy metal content.
Developing new lixiviant technologies requires a holistic
approach covering a multitude of functional requirements,
most of these relating to the overall process circuit, rather
than the leaching stage itself, where metals recovery from
leachates, reagent recovery and reuse, interaction with the
environment, controllability, safety and health, by-product
removal and valorization, water recovery and recycle and
waste disposal have to be attended to, while maintaining a
process that delivers acceptable recoveries within acceptable
capital and operating cost constraints. In gold and precious
metals processing, cyanide originally become a much envi-
ronmentally friendlier (and safer, despite its toxicity) alter-
native to mercury and caused a revolution in the industry at
the turn of the 20th century. We may be at such a turning
point again with yet another alternative lixiviant.
REFERENCES
Aylmore, M., Eksteen, J.J., Wells, M., Jones, M., 2019.
The mineralogy and processing potential of the
Commonwealth project in the Molong Volcanic Belt,
central eastern New South Wales, Australia, Australia.
Ore Geology Reviews. 111, 102976, 30 p.
Bezuidenhout, G.A., Eksteen, J.J., Akdogan, G. Van Beek,
B., Wendt, W. Persson, W., 2017. Implementation of
flame optical emission spectroscopy system for con-
verter Fe end-point control associated with Ni-Cu-S-
PGM converter mattes. Minerals Engineering, 100,
132–143.
Binnemans, K., Jones, P.T., 2023a. The Twelve Principles
of Circular Hydrometallurgy. Journal of Sustainable
Metallurgy, 9, 1–25.
Binnemans, K., Jones, P.T., 2023b. Ionic Liquids and
Deep‑Eutectic Solvents in Extractive Metallurgy:.
Mismatch Between Academic Research and Industrial
Applicability. Journal of Sustainable Metallurgy, 9,
423–438.
Cabri, L.J., Wilhelmij, H.R., Eksteen, J.J., 2017.
Contrasting mineralogical and processing potential of
two mineralization types in the platinum group ele-
ment and Ni-bearing Kapalagulu Intrusion, western
Tanzania. Ore Geology Reviews, 90, 772–789.
Corbett, M.K., Eksteen, J.J., Niu, X.-Z., Watkin, E.L.J.,
2017a. Incorporation of indigenous microorganisms
increases leaching rates of rare earth elements from
Western Australian monazite. Solid State Phenomena,
262 SSP, 294–298.
Corbett, M.K., Eksteen, J.J., Niu, X-Z, Croue, J.P.,
Watkin, E.L.J., 2017b. Interactions of phosphate solu-
bilising microorganisms with natural rare-earth phos-
phate minerals: a study utilizing Western Australian
monazite. Bioprocess and Biosystems Engineering, 40,
929–942.