XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3433
the anion of the medium, sulfuric acid (H2SO4), and the
counterion of manganese sulfate (MnSO4).
As predicted based on fundamentals of SX, essentially
only Mn was extracted in the first two extraction stages with
sodium and zinc as the only significant co-extracted impu-
rities. Figure 4 shows the extraction profile of manganese
and sodium over the eight extraction stages of the SX test.
It is known that sodium does not extract in Ionquest
220 under the conditions used in this work and it should
not have despite its presence in the feed (26 mg/L). The rea-
son for its apparent divergence from the theory was the use
of sodium hydroxide for controlling the pH, either the use
of saponified extractant, NaD2EHPA, or directly owing
to the use of NaOH for pH modification. Consequently,
its concentration in the feed was increasing as extraction
was progressing. Thus, at some point its concentration was
exceeding that of Mn. To maintain equilibrium, part of it
was obviously transferring to organic phase. Now that it is
known that Mn will extract even at high acidity, based on
its stripping profile, the use of NaOH can be minimised to
minimise its co-extraction.
The extraction of zinc on other hand is as expected,
based on its known extraction behaviour. Fortunately, both
metals are soluble even in low acidity and with very dif-
ferent electrochemical property from manganese. They
are therefore easier to address as an impurity in the final
Table 8. Assays of some strip solutions from the first extraction stage
Sample ID pH Al Ba Ca Co Cr Cu Fe K Mg Mn
Units mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
IX Raf 10.0 0.5 25.0 6.0 11 1.4 86 1,580 2.0 63,630
Dil Feed 0.76 2.0 0.1 5.0 1.2 2.2 0.3 17.2 316.0 0.4 12,726.0
E1 Strip 1 2.65 2.0 0.5 5.0 0.5 1.0 0.2 1.0 10 2.0 1074
E1 Strip 2 1.42 2.0 0.5 5.0 0.5 1.0 0.2 1.0 10 2.0 3,871
E1 Strip 3 1.01 2.0 0.5 5.0 0.5 1.0 0.2 1.0 10 2.0 953
Sample ID pH Na Ni P Pb S Si Ti V Zn Impurities
Units mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
IX Raf 28 9.5 10 0.5 56,500 3.0 1 0.4 4.4 1,767
Dil Feed 0.76 5.6 1.9 2 0.1 11,300 0.6 0.2 0.1 0.9 353
E1 Strip 1 2.65 6 0.5 20 0.5 730 1.0 1.0 0.2 0.2 26
E1 Strip 2 1.42 1.42 0.5 10 2 3,590 1.0 1.0 0.2 0.2 5.7
E1 Strip 3 1.01 4 0.5 10 1 3,340 1.0 1.0 0.2 1.2 6.2
Figure 4. Extraction loading of Mn and Na at various extraction stages
the anion of the medium, sulfuric acid (H2SO4), and the
counterion of manganese sulfate (MnSO4).
As predicted based on fundamentals of SX, essentially
only Mn was extracted in the first two extraction stages with
sodium and zinc as the only significant co-extracted impu-
rities. Figure 4 shows the extraction profile of manganese
and sodium over the eight extraction stages of the SX test.
It is known that sodium does not extract in Ionquest
220 under the conditions used in this work and it should
not have despite its presence in the feed (26 mg/L). The rea-
son for its apparent divergence from the theory was the use
of sodium hydroxide for controlling the pH, either the use
of saponified extractant, NaD2EHPA, or directly owing
to the use of NaOH for pH modification. Consequently,
its concentration in the feed was increasing as extraction
was progressing. Thus, at some point its concentration was
exceeding that of Mn. To maintain equilibrium, part of it
was obviously transferring to organic phase. Now that it is
known that Mn will extract even at high acidity, based on
its stripping profile, the use of NaOH can be minimised to
minimise its co-extraction.
The extraction of zinc on other hand is as expected,
based on its known extraction behaviour. Fortunately, both
metals are soluble even in low acidity and with very dif-
ferent electrochemical property from manganese. They
are therefore easier to address as an impurity in the final
Table 8. Assays of some strip solutions from the first extraction stage
Sample ID pH Al Ba Ca Co Cr Cu Fe K Mg Mn
Units mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
IX Raf 10.0 0.5 25.0 6.0 11 1.4 86 1,580 2.0 63,630
Dil Feed 0.76 2.0 0.1 5.0 1.2 2.2 0.3 17.2 316.0 0.4 12,726.0
E1 Strip 1 2.65 2.0 0.5 5.0 0.5 1.0 0.2 1.0 10 2.0 1074
E1 Strip 2 1.42 2.0 0.5 5.0 0.5 1.0 0.2 1.0 10 2.0 3,871
E1 Strip 3 1.01 2.0 0.5 5.0 0.5 1.0 0.2 1.0 10 2.0 953
Sample ID pH Na Ni P Pb S Si Ti V Zn Impurities
Units mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L mg/L
IX Raf 28 9.5 10 0.5 56,500 3.0 1 0.4 4.4 1,767
Dil Feed 0.76 5.6 1.9 2 0.1 11,300 0.6 0.2 0.1 0.9 353
E1 Strip 1 2.65 6 0.5 20 0.5 730 1.0 1.0 0.2 0.2 26
E1 Strip 2 1.42 1.42 0.5 10 2 3,590 1.0 1.0 0.2 0.2 5.7
E1 Strip 3 1.01 4 0.5 10 1 3,340 1.0 1.0 0.2 1.2 6.2
Figure 4. Extraction loading of Mn and Na at various extraction stages