XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3603
the elimination of atmospheric sulphur dioxide contamina-
tion whilst concurrently increasing production capabilities
in line with increased mining activities.
Ultimately, it was found that UFG to a P80 of between
10 to12 µm provided an 17% absolute uplift in gold recov-
ery (from 75% to 92%), highlighting the benefits of ultra
fine grinding prior to downstream metallurgical processes.
—————
Stage 3: Chemical Liberation (Oxidative Leaching)
Where gold is extremely refractory, ultrafine grinding alone
may be insufficient for high liberation and other treatment
may be required. Stage 3 involves the chemical liberation
of gold through the oxidation of the sulphide matrix, to
improve recoveries via downstream cyanide leaching.
As mentioned earlier, several commercialised processing
options exist for the treatment of sulfide minerals. The
decision as to which processing option is most suitable to
an operation should be based on the unique constraints of
each individual project, such as the jurisdiction of opera-
tion, local infrastructure and permitting, local communi-
ties and the social license to operate. In the application of
Glencore Technology processes, Stage 3 involves the build-
ing and commissioning of an Albion Process ™ oxidative
treatment plant utilising OxiLeach ™ reactors to chemically
break down the mineral sulphide matrix and render pre-
cious amenable to downstream cyanide leaching.
—————
Example 2: The Albion Process™ for Increased Gold
Recovery from Sulphide Ores
Source: (Voigt, Walker, Kloiber-Deane, &Tsvetkov, 2018)
The GeoProMining (GPM) Gold Project is located in
Armenia. It comprises an open cut mine (Zod) near the
Azerbaijan border, and a processing plant at Ararat near the
Turkish border. The Zod deposit contained both oxide and
sulphide ores. As the oxide ore was progressively depleted,
GPM sought to treat the underlying sulphide material, in
which gold is preferentially hosted in arsenopyrite, and to a
lesser extent pyrite and gold tellurides. The deposit has an
average sulfur grade of 1.4 %,average gold grade of 4.5 g/t,
average silver grade of 4.65 g/t, and average arsenic grade
of 0.3% w/w. The dominant gangue minerals are quartz,
talc and chlorite, and magnesite. The gold recovery from
sulphide minerals via conventional carbon-in-leach (CIL)
was only 20% to 30%, thus a pretreatment is required
prior to processing concentrate in the CIL circuit. A robust
plant capable of handling significant feed variation was of
importance due to the requirement to treat feed from seven
different ore bodies, including three that are high in arse-
nic. The Albion Process ™ was selected due to it’s robustness
and simplicity of operation, thus requiring a less technically
skilled workforce.
The Ararat processing plant was commissioned in
January 2014 and produces 120,000 oz of gold per annum.
The plant consists of an M3,000 IsaMill ™ and nine (9)
270 m3 OxiLeach ™ reactors. Whilst the plant was designed
to achieve a gold recovery of 92%, it frequently achieves recov-
eries above 95%. The plant is highly robust, able to operate
with high variability in feed throughput (Figure E2.1) and
sulphide content (Figure E2.2) and still achieve high gold
recoveries above 95%. During the process, arsenic is leached
into the bulk solution. The addition of limestone (to control
the pH to 5.5 within the range for optimal pyrite oxidation)
allows for the co-precipitation of iron and arsenic, forming a
stable ferroarsenate (predominantly scorodite). Subsequent
testing of the Ararat tailings storage facility have confirmed
the stability of the arsenic compounds.
—————
In any project, financial constraints are always a con-
sideration, particularly so if an operation may be looking
at stagewise implementation of processing to expedite rev-
enue to accommodate testwork, design and commissioning
of downstream processing options. Processes in which capi-
tal and operating expenditures can be minimised will be
strong contenders for such projects. Additionally, in adopt-
ing a stagewise approach, a flexible and robust downstream
processing option would allow for the opportunity to treat
varying concentrate grades and mineralogies (Example 2).
The Albion Process ™ boasts strong project economics
due to the simplicity of the process coupled with the ability
to control the extent of sulfide oxidation (i.e., testwork will
seek to minimise the percentage of sulfides oxidised while
still achieving high gold recoveries). It is also a robust pro-
cessing solution that can accommodate broad variations in
feed grades and mineralogy as evidenced by the real-world
example below.
The Albion Process ™ comprises fine grinding followed
by oxidative leaching. Feed material is finely ground in
Table E1.1. Fine Grinding Plant Design Parameters
Parameter Units Design
Throughput t/h 10
UFG Mill F80 μm 50
Gold recovery pre
fine grinding
%75
UFG Mill P80 μm 10–12
Gold Recovery post
fine grinding
%92
the elimination of atmospheric sulphur dioxide contamina-
tion whilst concurrently increasing production capabilities
in line with increased mining activities.
Ultimately, it was found that UFG to a P80 of between
10 to12 µm provided an 17% absolute uplift in gold recov-
ery (from 75% to 92%), highlighting the benefits of ultra
fine grinding prior to downstream metallurgical processes.
—————
Stage 3: Chemical Liberation (Oxidative Leaching)
Where gold is extremely refractory, ultrafine grinding alone
may be insufficient for high liberation and other treatment
may be required. Stage 3 involves the chemical liberation
of gold through the oxidation of the sulphide matrix, to
improve recoveries via downstream cyanide leaching.
As mentioned earlier, several commercialised processing
options exist for the treatment of sulfide minerals. The
decision as to which processing option is most suitable to
an operation should be based on the unique constraints of
each individual project, such as the jurisdiction of opera-
tion, local infrastructure and permitting, local communi-
ties and the social license to operate. In the application of
Glencore Technology processes, Stage 3 involves the build-
ing and commissioning of an Albion Process ™ oxidative
treatment plant utilising OxiLeach ™ reactors to chemically
break down the mineral sulphide matrix and render pre-
cious amenable to downstream cyanide leaching.
—————
Example 2: The Albion Process™ for Increased Gold
Recovery from Sulphide Ores
Source: (Voigt, Walker, Kloiber-Deane, &Tsvetkov, 2018)
The GeoProMining (GPM) Gold Project is located in
Armenia. It comprises an open cut mine (Zod) near the
Azerbaijan border, and a processing plant at Ararat near the
Turkish border. The Zod deposit contained both oxide and
sulphide ores. As the oxide ore was progressively depleted,
GPM sought to treat the underlying sulphide material, in
which gold is preferentially hosted in arsenopyrite, and to a
lesser extent pyrite and gold tellurides. The deposit has an
average sulfur grade of 1.4 %,average gold grade of 4.5 g/t,
average silver grade of 4.65 g/t, and average arsenic grade
of 0.3% w/w. The dominant gangue minerals are quartz,
talc and chlorite, and magnesite. The gold recovery from
sulphide minerals via conventional carbon-in-leach (CIL)
was only 20% to 30%, thus a pretreatment is required
prior to processing concentrate in the CIL circuit. A robust
plant capable of handling significant feed variation was of
importance due to the requirement to treat feed from seven
different ore bodies, including three that are high in arse-
nic. The Albion Process ™ was selected due to it’s robustness
and simplicity of operation, thus requiring a less technically
skilled workforce.
The Ararat processing plant was commissioned in
January 2014 and produces 120,000 oz of gold per annum.
The plant consists of an M3,000 IsaMill ™ and nine (9)
270 m3 OxiLeach ™ reactors. Whilst the plant was designed
to achieve a gold recovery of 92%, it frequently achieves recov-
eries above 95%. The plant is highly robust, able to operate
with high variability in feed throughput (Figure E2.1) and
sulphide content (Figure E2.2) and still achieve high gold
recoveries above 95%. During the process, arsenic is leached
into the bulk solution. The addition of limestone (to control
the pH to 5.5 within the range for optimal pyrite oxidation)
allows for the co-precipitation of iron and arsenic, forming a
stable ferroarsenate (predominantly scorodite). Subsequent
testing of the Ararat tailings storage facility have confirmed
the stability of the arsenic compounds.
—————
In any project, financial constraints are always a con-
sideration, particularly so if an operation may be looking
at stagewise implementation of processing to expedite rev-
enue to accommodate testwork, design and commissioning
of downstream processing options. Processes in which capi-
tal and operating expenditures can be minimised will be
strong contenders for such projects. Additionally, in adopt-
ing a stagewise approach, a flexible and robust downstream
processing option would allow for the opportunity to treat
varying concentrate grades and mineralogies (Example 2).
The Albion Process ™ boasts strong project economics
due to the simplicity of the process coupled with the ability
to control the extent of sulfide oxidation (i.e., testwork will
seek to minimise the percentage of sulfides oxidised while
still achieving high gold recoveries). It is also a robust pro-
cessing solution that can accommodate broad variations in
feed grades and mineralogy as evidenced by the real-world
example below.
The Albion Process ™ comprises fine grinding followed
by oxidative leaching. Feed material is finely ground in
Table E1.1. Fine Grinding Plant Design Parameters
Parameter Units Design
Throughput t/h 10
UFG Mill F80 μm 50
Gold recovery pre
fine grinding
%75
UFG Mill P80 μm 10–12
Gold Recovery post
fine grinding
%92