IM 2017 August 17 | Page 45

GOLD EXTRACTION
also extended the range of applications beyond
its well-known Leachox process for refractory
gold processing.
The Aachen shear reactor is essentially a
highly efficient mass transfer device developed
and refined over many years out of experience
with Maelgwyn’ s Imhoflot flotation technology.
The versatility of the reactor is evident by the
ever-growing list of different process
applications. These include:
n Mild pre-oxygenation to reduce cyanide
consumption through oxidation of cyanide
consuming species combined with efficient
oxygen utilisation
n Aachen assisted leaching (AAL). As a highly
efficient mass transfer device and also a
shear reactor Aachen reactors are finding
increasing applications within gold and silver
leach circuits to accelerate leach kinetics,
reduce cyanide consumption and reduce
surface passivation
n Partial sulphide oxidation (typically up to 60-
70%).This role is normally as part of the
Leachox process and when combined with
ultra-fine grinding can significantly increase
gold recovery for refractory flotation
concentrates through partial oxidation of the
sulphide matrix
n For cyanide destruction by supplementing the
INCO process when oxygen is rate
determining
n Tailing treatment operations
A large Aachen reactor
installation in the DRC
where kinetics are constrained
due to high throughputs.
Currently there are over 40 Aachen
reactors installed across various
operations and processes but mainly
installed in pre-oxidation and Aachen
assisted leaching roles.
As every orebody is different the
benefits vary from operation to
operation depending upon how
optimised the cyanidation circuit is
but gold recovery benefits of up to
5% have been realised. The typical
benefits include:
n Increase in gold recovery
n Enhanced kinetics
n Reduced cyanide consumption
and reduced lime consumption
n Downstream benefits for carbon
plants due to steeper leach
profiles
n Improved oxygen utilisation
n Lower residual cyanide
concentrations.
during the regrind resulted in a low Eh and
One Australian gold mine that already had an
dissolved oxygen level. Following consultation
Aachen reactor on site for the cyanidation circuit
was experiencing difficulties in floating copper
and gold minerals after regrinding a pyrite
rougher concentrate. The high oxygen
consumption of fresh pyrite surfaces created
with MMS it successfully trialled the leach
Aachen to boost the DO level for this application
with this installation now being made permanent.
The Aachen units can be manufactured in a
range of sizes to suit the site-specific flow rate
“Innovative
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Glencore Technology has the expertise to get the most from your operation.
Whether it is mineral processing, hydrometallurgy, smelting or copper refining and electrowinning,
Glencore Technology offer a range of solutions and services that can make a difference.
www.glencoretechnology.com
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