1
25-073
Pressure Acid Leaching of Seabed Polymetallic Nodules—
An Update
Niels Verbaan
SGS Canada, Lakefield, Canada
Mike Johnson
SGS Canada, Lakefield, Canada
Tassos Grammatikopoulos
SGS Canada, Lakefield, Canada
ABSTRACT
Seabed polymetallic nodules, which contain significant
quantities of metals key to electrification (nickel, cobalt,
copper, and manganese) can be processed using several dif-
ferent metallurgical processing options, including direct
smelting and subsequent hydrometallurgical refining of the
copper/nickel matte, ammoniacal leaching (gas reduction
or Cuprion), and acid leaching (often reductive). Many of
these approaches suffer from reduced cobalt extraction, dif-
ficult physical performance, or overall circuit complexity
in general, leading to increased risk to the overall project.
SGS has considered pressure acid leaching of nodules for
further investigation, as publicly shared data on this pro-
cessing route stems from the 1970s and 1980s and is not
always easily accessible. This paper will detail the series of
tests conducted and provide updated results obtained (high
Ni/Co/Cu recovery with limited Mn/Fe), as well as com-
ment on the potential treatment options on the product
solution and residue.
Keywords: Nickel, Cobalt, Copper, Nodules, Seabed
Nodules, Deep Sea Nodules, Polymetallic, Manganese,
Pressure Acid Leaching.
BACKGROUND AND INTRODUCTION
Polymetallic manganese nodules are a noteworthy poten-
tial feed source for cobalt, nickel, copper, and manganese,
occurring in the deep ocean, for example in the Pacific
Ocean between Mexico and Hawaii. Other oceans contain
nodules as well, though their metal contents differ accord-
ing to their location. Containing significant quantities of
nickel, cobalt, copper, manganese, and various critical met-
als, Table 1 shows the general composition of nodules from
the ClarionClipperton Zone (CCZ) in the Pacific Ocean.
An evaluation of the average nodule composition
reveals that a significant percentage (66%) of the contained
value is associated with nickel, cobalt, and copper while
34% of the contained value is associated with manganese,
if it is assumed to be recovered as High Purity Manganese
Sulphate Mono Hydrate, (HPMSM), which contains 32%
Mn and is worth about USD 2000/t. However, it is not
practical to assume that all manganese contained in a nod-
ule processing operation will advance to HPMSM. The
Metals Company (TMC) [2] proposes a nodule processing
capacity of 6.4 Mtpa, which if all contained manganese is
processed into HPMSM, would equate to 70–75 produc-
tion trains at 65,000 t/a of HPMSM which far outweighs
the market demand for HPMSM. Based on their feasibility
study, Element 25 Limited (E25) [3] proposes to construct
two such production trains each at 65,000 t/a of HPMSM
for a total of 130,000 t/a. Therefore, it may be more real-
istic to use a manganese ore price (assumed at 130 USD/t
ore at 32% Mn). Using this assumption, 97% of the poten-
tial revenue from nodules is associated with copper, nickel,
and cobalt, and only 3% with manganese (though hybrid
approaches targeting multiple Mn products could also be
Table 1. Average composition of seabed nodules from pacific
deposits [1]
Element Ni Co Cu Fe Mn Si
Average
Composition (%)
0.99 0.35 0.53 14 24.2 9.4
25-073
Pressure Acid Leaching of Seabed Polymetallic Nodules—
An Update
Niels Verbaan
SGS Canada, Lakefield, Canada
Mike Johnson
SGS Canada, Lakefield, Canada
Tassos Grammatikopoulos
SGS Canada, Lakefield, Canada
ABSTRACT
Seabed polymetallic nodules, which contain significant
quantities of metals key to electrification (nickel, cobalt,
copper, and manganese) can be processed using several dif-
ferent metallurgical processing options, including direct
smelting and subsequent hydrometallurgical refining of the
copper/nickel matte, ammoniacal leaching (gas reduction
or Cuprion), and acid leaching (often reductive). Many of
these approaches suffer from reduced cobalt extraction, dif-
ficult physical performance, or overall circuit complexity
in general, leading to increased risk to the overall project.
SGS has considered pressure acid leaching of nodules for
further investigation, as publicly shared data on this pro-
cessing route stems from the 1970s and 1980s and is not
always easily accessible. This paper will detail the series of
tests conducted and provide updated results obtained (high
Ni/Co/Cu recovery with limited Mn/Fe), as well as com-
ment on the potential treatment options on the product
solution and residue.
Keywords: Nickel, Cobalt, Copper, Nodules, Seabed
Nodules, Deep Sea Nodules, Polymetallic, Manganese,
Pressure Acid Leaching.
BACKGROUND AND INTRODUCTION
Polymetallic manganese nodules are a noteworthy poten-
tial feed source for cobalt, nickel, copper, and manganese,
occurring in the deep ocean, for example in the Pacific
Ocean between Mexico and Hawaii. Other oceans contain
nodules as well, though their metal contents differ accord-
ing to their location. Containing significant quantities of
nickel, cobalt, copper, manganese, and various critical met-
als, Table 1 shows the general composition of nodules from
the ClarionClipperton Zone (CCZ) in the Pacific Ocean.
An evaluation of the average nodule composition
reveals that a significant percentage (66%) of the contained
value is associated with nickel, cobalt, and copper while
34% of the contained value is associated with manganese,
if it is assumed to be recovered as High Purity Manganese
Sulphate Mono Hydrate, (HPMSM), which contains 32%
Mn and is worth about USD 2000/t. However, it is not
practical to assume that all manganese contained in a nod-
ule processing operation will advance to HPMSM. The
Metals Company (TMC) [2] proposes a nodule processing
capacity of 6.4 Mtpa, which if all contained manganese is
processed into HPMSM, would equate to 70–75 produc-
tion trains at 65,000 t/a of HPMSM which far outweighs
the market demand for HPMSM. Based on their feasibility
study, Element 25 Limited (E25) [3] proposes to construct
two such production trains each at 65,000 t/a of HPMSM
for a total of 130,000 t/a. Therefore, it may be more real-
istic to use a manganese ore price (assumed at 130 USD/t
ore at 32% Mn). Using this assumption, 97% of the poten-
tial revenue from nodules is associated with copper, nickel,
and cobalt, and only 3% with manganese (though hybrid
approaches targeting multiple Mn products could also be
Table 1. Average composition of seabed nodules from pacific
deposits [1]
Element Ni Co Cu Fe Mn Si
Average
Composition (%)
0.99 0.35 0.53 14 24.2 9.4