3402 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
Technology Selection
There are various ion exchange technologies used in the
industry and the choice of the technology depends on
parameters such as the feed composition, targeted elution
frequency and the nature of the feed stream (slurry or solu-
tion). The ion exchange technologies used in the industry
include static (fixed bed column), continuous (moving bed)
or a combination such as counter-current ion exchange.
Furthermore, resin-in-pulp (RIP) or resin-in-leach (RIL)
provide solutions to challenging process conditions such
as poor filtration and washability, or to improve efficiency
where equilibrium leach conditions exist.
The recovery or the rejection of base metals impuri-
ties from a Mn solution by ion exchange usually comprises
adsorption, elution/regeneration and conditioning steps. In
the adsorption step, the selected resin is contacted with the
feed containing Mn and impurities. The metal impurities
are then loaded onto the resin. The loaded resin is washed
and then eluted to remove the ions that had been loaded
onto the resin. In this way the resin activity is regenerated.
During regeneration the loaded ion is replaced with regen-
eration ion (e.g., H+, or OH–). The regeneration steps,
which entails contacting the resin with high concentration
of mineral acid (i.e sulfuric acid) or salt (NaCl) displaces
the metal impurities from the resin and loads ions from the
regeneration solution (H+ or Cl– in the examples given).
However, in certain cases a further stage of conditioning is
required, to swap acidic ions for a neutral ion. For example,
resin loaded with H+ ions may be treated with NaOH, to
replace the proton with a neutral Na+ ion.
Case Examples
The work presented by P. Littlejohn and J. Vaughan indi-
cated that the resins with iminodiacetic acid functional
groups have a higher operational capacity but poorer
selectivity for Ni and Co over Fe, Al, Mn, Mg, and Ca.
Alternatively, resins with picolylamine functional groups
offer improved selectivity of Ni and Co over other metals
but offer poor operational capacity.
A method using ion exchange for purification of man-
ganese sulfate solutions was reported by Kholmogorov et al.
(1997). It was found that Co extraction increased with an
increase in pH up to 5.5. The Mn separation was achieved
by substituting the Mn ions with Co ions at pH more than
3.5 using IDA resins. The cobalt content in the resulting
manganese sulfate solutions was below 0.6 mg/L.
Kudryavtsev et al. (1991) used a polyethylene-poly-
amine type ion exchanger for separation of Co and Mn in
sulfate solutions. The ion exchanger was pre-treated with
mineral acids at pH 3–3.5.
PRECIPITATION OF MANGANESE
Fe and K Removal by Precipitation Processes
The first stage after reductive sulfuric acid leaching is typi-
cally precipitation to remove monovalent impurities (K
and/or Na) and Fe from the PLS. Ward (2011) presented a
process that involved a two-stage precipitation process for
removal of K and Fe as jarosite and goethite. The first stage
precipitation was conducted on Mn rich PLS by adjusting
the pH to 2.3 -2.6 using 10% -20% lime at elevated tem-
perature of about 90°C (Kim and Tran, 2015). Air was used
as an oxidant. The reaction proceeds for about 3 hours, dur-
ing which K is precipitated according to equation below:
3Fe2(SO4)3 +K2SO4 +3 Ca(OH)2 → 2KFe3(SO4)2(OH)6
+3 CaSO4 +3SO4– (21)
Potassium is therefore removed as K-Jarosite. Slurry
from the jarosite precipitation was submitted to second
stage precipitation, for removal of Fe and any present Al.
This was attained by further increasing pH using lime, to
a target of 4–5.5. The higher terminal pH also results in
the partial precipitation of remaining base metal impuri-
ties. Thickening of slurry and filtration of underflow could
then be used to separate the precipitation products from
the Mn overflow for subsequent Mn recovery purification
processes.
Heavy Metal Removal by Precipitation
The Fe and K depleted PLS is still laden with heavy met-
als like Cu, Ni, Pb and Zn. These can be removed by a
Figure 5. Adsorption of certain metals on IDA chelating
resin as a function of pH (Xiangzhi, 2016)
Technology Selection
There are various ion exchange technologies used in the
industry and the choice of the technology depends on
parameters such as the feed composition, targeted elution
frequency and the nature of the feed stream (slurry or solu-
tion). The ion exchange technologies used in the industry
include static (fixed bed column), continuous (moving bed)
or a combination such as counter-current ion exchange.
Furthermore, resin-in-pulp (RIP) or resin-in-leach (RIL)
provide solutions to challenging process conditions such
as poor filtration and washability, or to improve efficiency
where equilibrium leach conditions exist.
The recovery or the rejection of base metals impuri-
ties from a Mn solution by ion exchange usually comprises
adsorption, elution/regeneration and conditioning steps. In
the adsorption step, the selected resin is contacted with the
feed containing Mn and impurities. The metal impurities
are then loaded onto the resin. The loaded resin is washed
and then eluted to remove the ions that had been loaded
onto the resin. In this way the resin activity is regenerated.
During regeneration the loaded ion is replaced with regen-
eration ion (e.g., H+, or OH–). The regeneration steps,
which entails contacting the resin with high concentration
of mineral acid (i.e sulfuric acid) or salt (NaCl) displaces
the metal impurities from the resin and loads ions from the
regeneration solution (H+ or Cl– in the examples given).
However, in certain cases a further stage of conditioning is
required, to swap acidic ions for a neutral ion. For example,
resin loaded with H+ ions may be treated with NaOH, to
replace the proton with a neutral Na+ ion.
Case Examples
The work presented by P. Littlejohn and J. Vaughan indi-
cated that the resins with iminodiacetic acid functional
groups have a higher operational capacity but poorer
selectivity for Ni and Co over Fe, Al, Mn, Mg, and Ca.
Alternatively, resins with picolylamine functional groups
offer improved selectivity of Ni and Co over other metals
but offer poor operational capacity.
A method using ion exchange for purification of man-
ganese sulfate solutions was reported by Kholmogorov et al.
(1997). It was found that Co extraction increased with an
increase in pH up to 5.5. The Mn separation was achieved
by substituting the Mn ions with Co ions at pH more than
3.5 using IDA resins. The cobalt content in the resulting
manganese sulfate solutions was below 0.6 mg/L.
Kudryavtsev et al. (1991) used a polyethylene-poly-
amine type ion exchanger for separation of Co and Mn in
sulfate solutions. The ion exchanger was pre-treated with
mineral acids at pH 3–3.5.
PRECIPITATION OF MANGANESE
Fe and K Removal by Precipitation Processes
The first stage after reductive sulfuric acid leaching is typi-
cally precipitation to remove monovalent impurities (K
and/or Na) and Fe from the PLS. Ward (2011) presented a
process that involved a two-stage precipitation process for
removal of K and Fe as jarosite and goethite. The first stage
precipitation was conducted on Mn rich PLS by adjusting
the pH to 2.3 -2.6 using 10% -20% lime at elevated tem-
perature of about 90°C (Kim and Tran, 2015). Air was used
as an oxidant. The reaction proceeds for about 3 hours, dur-
ing which K is precipitated according to equation below:
3Fe2(SO4)3 +K2SO4 +3 Ca(OH)2 → 2KFe3(SO4)2(OH)6
+3 CaSO4 +3SO4– (21)
Potassium is therefore removed as K-Jarosite. Slurry
from the jarosite precipitation was submitted to second
stage precipitation, for removal of Fe and any present Al.
This was attained by further increasing pH using lime, to
a target of 4–5.5. The higher terminal pH also results in
the partial precipitation of remaining base metal impuri-
ties. Thickening of slurry and filtration of underflow could
then be used to separate the precipitation products from
the Mn overflow for subsequent Mn recovery purification
processes.
Heavy Metal Removal by Precipitation
The Fe and K depleted PLS is still laden with heavy met-
als like Cu, Ni, Pb and Zn. These can be removed by a
Figure 5. Adsorption of certain metals on IDA chelating
resin as a function of pH (Xiangzhi, 2016)