XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 325
Further Research on Nodule Processing
Investigations into nodules and similar materials (oceanic
crusts) continued over time, primarily in China and India
with the goal of developing alternatives to the limited num-
ber of existing terrestrial sources of manganese, cobalt, and
other critical metals.
The Beijing General Research Institute of Mining and
Metallurgy (BGRIMM) had been involved with this work
for several years when they presented a paper (ALTA 2016).
on some results of its testing at the ALTA 2016 confer-
ence in Perth, Western Australia. This testing confirmed
that using the original Cuprion ammonium carbonate
process resulted in limited cobalt extractions as the cobalt
concentration in the leachate increased. However, using a
Cuprion ammonium sulfate process did not have the same
limitations. This paper attracted the attention of Dr. Colin
Seaborn, Chief Metallurgist of Ocean Minerals, Limited
(OML), the parent company of Moana Minerals.
OML-BGRIMM Modified Cuprion (Sulfate) Process
Testing
In January 2020, OML collected samples of Cook Islands
nodules using free fall grabs as part of a permitted research
program. Approximately 100kg of nodule material was
provided to BGRIMM which was contracted to conduct,
under the direction of OML, a bench scale laboratory
testing and development program of a modified Cuprion
process to extract cobalt, copper, and nickel from Cook
Islands nodules.
The result of the OML-BGRIMM development and
testing program was a set of modifications of the basic
Cuprion process (hereafter referred to as Cuprion Sulfate
process) as represented in Figure 4. Two key changes were
implemented to try and address Cobalt recovery optimi-
zation. The first included conducting the reduction leach
at lower temperature than the original Cuprion process
(30°C instead of 50°C). The second was to use ammonium
sulfate instead of ammonium carbonate as the lixiviant in
the reducing leach. Both changes increased the potential
solubility of cobalt in the leachate. These changes resulted
in achieving up to 93% extraction of the cobalt, while still
achieving 90% extraction of the nickel and 60% extraction
of the copper into the leachate. Both changes appeared to
be necessary as demonstrated by tests conducted with the
standard Cuprion conditions which performed poorly.
Due to the need to conserve the relatively small num-
ber of nodules provided, BGRIMM conducted most leach
tests on 10-gram splits of ground nodules. The leach tests
used 400 ml of lixiviant solution and were therefore run at
2.5% solids by weight. BGRIMM did attempt to run tests
at higher solids concentration, but the leaching extractions
were low. This may have been due to “reagent starvation”
that prevented reduction of sufficient manganese to liberate
the desired metals.
As shown above in Figures 3 and 4, in a continuous
operation of both the Cuprion and Cuprion Sulfate (here-
after referred to as Cuprion Sulfate) process, pregnant solu-
tion is recycled from the post leach solid/liquid separation,
to ensure sufficient cuprous copper is available to start the
manganese reduction. Therefore, the lixiviant solution fed
to the batch tests has included cuprous copper in the mix,
to provide the necessary reductant for the manganese dur-
ing the leach as well as additions of cobalt, manganese, and
nickel to simulate recycled pregnant solution.
The scale of the BGRIMM tests did not permit dem-
onstration of downstream metal recovery processes, with
actual leach solutions and residues. However, BGRIMM
did demonstrate those steps with simulated leach solutions
and residues.
While the use of ammonium sulfate did increase the
extraction of cobalt to the pregnant leachate, it had a simi-
lar effect on manganese. Manganese sulfate (with Mn in
the +2-oxidation state) is much more soluble than manga-
nese+2 carbonate, which resulted in an extraction of 50%
to 60% of the manganese in the nodules. BGRIMM dealt
with this in two steps.
The fraction of the diluted pregnant liquor advanced
to metal recovery was aerated to oxidize both cobalt and
manganese. The oxidized cobalt remained in solution but
was easier to separate from the copper and nickel.
The oxidized manganese precipitated as manganese
oxide which was returned to the leach circuit. In the leach
circuit this solid manganese oxide reacts with carbon diox-
ide formed in the reduction of cupric copper to cuprous
copper to form manganese carbonate. This manganese
carbonate can then be recovered from the leach residue by
froth flotation to create another potentially salable product.
BGRIMM demonstrated that copper and nickel can
be separated from a simulated oxidized leach liquor stream
by solvent extraction. They further demonstrated that
both metals can then be stripped from the organic sol-
vent and recovered by electrowinning. BGRIMM analysis
of the resulting EW metals showed extremely high purity
nickel and copper metals (i.e., cathode quality). Alternative
recovery routes and products will be investigated in future
testing.
Cobalt was next recovered from the copper-nickel sol-
vent extraction raffinate by stripping ammonia from the
solution by bubbling steam through the raffinate. Cobalt
was then precipitated from the solution as cobalt hydroxide.
Further Research on Nodule Processing
Investigations into nodules and similar materials (oceanic
crusts) continued over time, primarily in China and India
with the goal of developing alternatives to the limited num-
ber of existing terrestrial sources of manganese, cobalt, and
other critical metals.
The Beijing General Research Institute of Mining and
Metallurgy (BGRIMM) had been involved with this work
for several years when they presented a paper (ALTA 2016).
on some results of its testing at the ALTA 2016 confer-
ence in Perth, Western Australia. This testing confirmed
that using the original Cuprion ammonium carbonate
process resulted in limited cobalt extractions as the cobalt
concentration in the leachate increased. However, using a
Cuprion ammonium sulfate process did not have the same
limitations. This paper attracted the attention of Dr. Colin
Seaborn, Chief Metallurgist of Ocean Minerals, Limited
(OML), the parent company of Moana Minerals.
OML-BGRIMM Modified Cuprion (Sulfate) Process
Testing
In January 2020, OML collected samples of Cook Islands
nodules using free fall grabs as part of a permitted research
program. Approximately 100kg of nodule material was
provided to BGRIMM which was contracted to conduct,
under the direction of OML, a bench scale laboratory
testing and development program of a modified Cuprion
process to extract cobalt, copper, and nickel from Cook
Islands nodules.
The result of the OML-BGRIMM development and
testing program was a set of modifications of the basic
Cuprion process (hereafter referred to as Cuprion Sulfate
process) as represented in Figure 4. Two key changes were
implemented to try and address Cobalt recovery optimi-
zation. The first included conducting the reduction leach
at lower temperature than the original Cuprion process
(30°C instead of 50°C). The second was to use ammonium
sulfate instead of ammonium carbonate as the lixiviant in
the reducing leach. Both changes increased the potential
solubility of cobalt in the leachate. These changes resulted
in achieving up to 93% extraction of the cobalt, while still
achieving 90% extraction of the nickel and 60% extraction
of the copper into the leachate. Both changes appeared to
be necessary as demonstrated by tests conducted with the
standard Cuprion conditions which performed poorly.
Due to the need to conserve the relatively small num-
ber of nodules provided, BGRIMM conducted most leach
tests on 10-gram splits of ground nodules. The leach tests
used 400 ml of lixiviant solution and were therefore run at
2.5% solids by weight. BGRIMM did attempt to run tests
at higher solids concentration, but the leaching extractions
were low. This may have been due to “reagent starvation”
that prevented reduction of sufficient manganese to liberate
the desired metals.
As shown above in Figures 3 and 4, in a continuous
operation of both the Cuprion and Cuprion Sulfate (here-
after referred to as Cuprion Sulfate) process, pregnant solu-
tion is recycled from the post leach solid/liquid separation,
to ensure sufficient cuprous copper is available to start the
manganese reduction. Therefore, the lixiviant solution fed
to the batch tests has included cuprous copper in the mix,
to provide the necessary reductant for the manganese dur-
ing the leach as well as additions of cobalt, manganese, and
nickel to simulate recycled pregnant solution.
The scale of the BGRIMM tests did not permit dem-
onstration of downstream metal recovery processes, with
actual leach solutions and residues. However, BGRIMM
did demonstrate those steps with simulated leach solutions
and residues.
While the use of ammonium sulfate did increase the
extraction of cobalt to the pregnant leachate, it had a simi-
lar effect on manganese. Manganese sulfate (with Mn in
the +2-oxidation state) is much more soluble than manga-
nese+2 carbonate, which resulted in an extraction of 50%
to 60% of the manganese in the nodules. BGRIMM dealt
with this in two steps.
The fraction of the diluted pregnant liquor advanced
to metal recovery was aerated to oxidize both cobalt and
manganese. The oxidized cobalt remained in solution but
was easier to separate from the copper and nickel.
The oxidized manganese precipitated as manganese
oxide which was returned to the leach circuit. In the leach
circuit this solid manganese oxide reacts with carbon diox-
ide formed in the reduction of cupric copper to cuprous
copper to form manganese carbonate. This manganese
carbonate can then be recovered from the leach residue by
froth flotation to create another potentially salable product.
BGRIMM demonstrated that copper and nickel can
be separated from a simulated oxidized leach liquor stream
by solvent extraction. They further demonstrated that
both metals can then be stripped from the organic sol-
vent and recovered by electrowinning. BGRIMM analysis
of the resulting EW metals showed extremely high purity
nickel and copper metals (i.e., cathode quality). Alternative
recovery routes and products will be investigated in future
testing.
Cobalt was next recovered from the copper-nickel sol-
vent extraction raffinate by stripping ammonia from the
solution by bubbling steam through the raffinate. Cobalt
was then precipitated from the solution as cobalt hydroxide.