3424 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
methods and solvent extraction methods were attempted
and the successful technique are included in this paper.
Neutralisation
The objective was to remove impurities by precipitating the
respective hydroxides by adding hydrated lime as the pre-
cipitation agent. The target impurities were mainly Al, Fe,
Si and Zn. This process did not have any effect on Ca, Mg
and K in the solution. Neutralisation trials targeting differ-
ent end pH values were conducted. The metal removal effi-
ciencies are shown in Table 5. The target impurities removal
was almost 100% whilst the Mn loss was insignificant.
Solvent Extraction
Neutralised PLS solution was used for solvent extraction
(SX). The main objective of this process was to remove Ca
and Mg from the solution. Cyanex 272 was used as the
extractant. Three SX-stripping cycles were required for
mud PLS. The final stripped solution (from mud PLS)
contained about 44 g/L of Mn and interestingly Ca and
Mg concentrations were 10 and 12 mg/L, respectively. As
summarised in Table 6, under the tested conditions, 70%
of Mn is extracted and, from that amount 79% is reporting
to the final stripping solution, which was used for crystalli-
sation process. The extraction of Ca and Mg were 18% and
15%, respectively whilst only 10% and 4% are reported to
the final stripping solution.
Extraction, scrubbing and stripping percentages were
calculated according to Eq (2)–(4).
Extraction, %in initial aq. solh
in initial aq. sol
mass in
equilibrium aq. sol
*100 =
Jmass
L
K
K-
K
^mass
N
P
O
O
O
(2)
Scrubbing, %(mass in loaded organic)
(mass in scrubbing sol)
*100 =(3)
Stripping, %(mass in loaded organic)
(mass in stripping sol)
*100 =(4)
Crystallisation
A lab scale crystallisation test was performed using Mud
process solution. The feed was the final stripped solution of
solvent extraction process. Evaporative crystallisation was
performed using a simple lab setup using a beaker and hot
plate to produce MnSO4. The remaining mother liquor
and the crystals were analysed by ICP and XRF, respec-
tively as shown in Table 7. The crystals consist of 31.6%
of Mn and 19.5% of S. All the other elements are below
the detection limits, except the Mg. However, to get more
accurate results, the crystallisation should be performed in
an evaporative crystalliser to avoid any contaminations by
stirring equipment and temperature probes in future. The
specifications for class II HPMSM are also included in the
table for comparison purposes. Class I HPMSM required a
minimum of 32% of Mn.
Table 5. Mud PLS neutralisation test outcomes
Description Al Fe Mn S Si Sr Zn
Mud PLS, mg/L 1800 2350 84500 60500 250 20 1500
Removal efficiency, %100% 100% 6% 11% 95% 70% 100%
Table 6. Solvent extraction test outcomes of neutralised mud
PLS after three cycles
Process Ca Mg Mn
Extraction %18% 15% 70%
Scrubbing %9% 14% 5%
Stripping %10% 4% 79%
Table 7. Crystallisation test results of mud processes solutions and industry standards for HPMSM
Sample Description Units Ca Cd Co Cu Fe K Mg Mn Na Ni Zn
Feed solution mg/L 10 1.5 0.5 1.8 8 10 12 44050 132 0.5 14.8
MnSO4 crystals %0.01 #0.002 0.01 0.01 0.01 0.06 31.6 #0.01 0.01
Chinese standard
Specification- Class II
HPMSM
W% ≤0.02 ≤0.001 x ≤0.002 ≤0.002 ≤0.001 ≤0.02 ≥31.8 ≤0.01 x ≤0.002
Industry Specification
ISKY
max
ppm
50 10 50 10 10 100 50 ≥31.8% 50 50 10
x- not specified.
#-not analysed.
methods and solvent extraction methods were attempted
and the successful technique are included in this paper.
Neutralisation
The objective was to remove impurities by precipitating the
respective hydroxides by adding hydrated lime as the pre-
cipitation agent. The target impurities were mainly Al, Fe,
Si and Zn. This process did not have any effect on Ca, Mg
and K in the solution. Neutralisation trials targeting differ-
ent end pH values were conducted. The metal removal effi-
ciencies are shown in Table 5. The target impurities removal
was almost 100% whilst the Mn loss was insignificant.
Solvent Extraction
Neutralised PLS solution was used for solvent extraction
(SX). The main objective of this process was to remove Ca
and Mg from the solution. Cyanex 272 was used as the
extractant. Three SX-stripping cycles were required for
mud PLS. The final stripped solution (from mud PLS)
contained about 44 g/L of Mn and interestingly Ca and
Mg concentrations were 10 and 12 mg/L, respectively. As
summarised in Table 6, under the tested conditions, 70%
of Mn is extracted and, from that amount 79% is reporting
to the final stripping solution, which was used for crystalli-
sation process. The extraction of Ca and Mg were 18% and
15%, respectively whilst only 10% and 4% are reported to
the final stripping solution.
Extraction, scrubbing and stripping percentages were
calculated according to Eq (2)–(4).
Extraction, %in initial aq. solh
in initial aq. sol
mass in
equilibrium aq. sol
*100 =
Jmass
L
K
K-
K
^mass
N
P
O
O
O
(2)
Scrubbing, %(mass in loaded organic)
(mass in scrubbing sol)
*100 =(3)
Stripping, %(mass in loaded organic)
(mass in stripping sol)
*100 =(4)
Crystallisation
A lab scale crystallisation test was performed using Mud
process solution. The feed was the final stripped solution of
solvent extraction process. Evaporative crystallisation was
performed using a simple lab setup using a beaker and hot
plate to produce MnSO4. The remaining mother liquor
and the crystals were analysed by ICP and XRF, respec-
tively as shown in Table 7. The crystals consist of 31.6%
of Mn and 19.5% of S. All the other elements are below
the detection limits, except the Mg. However, to get more
accurate results, the crystallisation should be performed in
an evaporative crystalliser to avoid any contaminations by
stirring equipment and temperature probes in future. The
specifications for class II HPMSM are also included in the
table for comparison purposes. Class I HPMSM required a
minimum of 32% of Mn.
Table 5. Mud PLS neutralisation test outcomes
Description Al Fe Mn S Si Sr Zn
Mud PLS, mg/L 1800 2350 84500 60500 250 20 1500
Removal efficiency, %100% 100% 6% 11% 95% 70% 100%
Table 6. Solvent extraction test outcomes of neutralised mud
PLS after three cycles
Process Ca Mg Mn
Extraction %18% 15% 70%
Scrubbing %9% 14% 5%
Stripping %10% 4% 79%
Table 7. Crystallisation test results of mud processes solutions and industry standards for HPMSM
Sample Description Units Ca Cd Co Cu Fe K Mg Mn Na Ni Zn
Feed solution mg/L 10 1.5 0.5 1.8 8 10 12 44050 132 0.5 14.8
MnSO4 crystals %0.01 #0.002 0.01 0.01 0.01 0.06 31.6 #0.01 0.01
Chinese standard
Specification- Class II
HPMSM
W% ≤0.02 ≤0.001 x ≤0.002 ≤0.002 ≤0.001 ≤0.02 ≥31.8 ≤0.01 x ≤0.002
Industry Specification
ISKY
max
ppm
50 10 50 10 10 100 50 ≥31.8% 50 50 10
x- not specified.
#-not analysed.