XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 3423
method. The results are summarised in Table 3. According
to QXRD analysis, the mud mainly consisted of rhodo-
chrosite (MnCO3). The rest contained a 3% of mangan-
osite (MnO) and 47% of amorphous content, however the
composition is unknown.
An Eh-pH diagram generated from HSC system is
given in Figure 4. In this scenario equal molality for Mn
and S at 25 °C was assumed.
Leaching
Mud Leaching
Direct acid leaching with sulfuric acid was performed for
mud. The reaction between sulfuric acid and MnCO3 is
given in Eq.(1). As shown, this reaction produces MnSO4
and releases CO2 gas.
MnCO3 +H2SO4 =MnSO4 +H2O +CO2 (1)
Few preliminary acid leaching tests were performed by add-
ing different acid dosages. Accordingly, in average 2M of
98% H2SO4 acid was used for the mud leaching at room
temperature for two hours. The foaming was significant
and the container size must be large enough to accommo-
date the generated foam during the lab-scale experiments
to prevent foam overflowing. A foam mitigation technique
should be used in bulk lab tests and pilot scale tests. The
average assay results of mud leach solutions are given in
Table 4.
Leach Solution Purification
The purification of resulted leachate from mud processing
will be discussed in the following sections. The presence
of different impurities necessitated multiple purifica-
tion methods to obtain a sufficiently pure solution prior
to MnSO4 crystallisation process. Various precipitation
Table 3. QXRD analysis data of mud
Mineral Mineral Formula Composition
Manganosite Mn(II)O 3
Rhodochrosite Mn(II)(CO₃) 50
Amorphous content Unknown 47
Figure 4. Eh-pH diagram of Mn-S-C system at 25 °C generated from HSC software
Table 4. Mud leach solution assay (average values) and leaching efficiency of different elements
Test Al Ca Fe K Mg Mn Na S Si Sr Zn
Assay, mg/L 1800 500 2350 1800 2000 84500 1200 59000 300 16 1500
Extraction, %56% 10% 32% 95% 91% 84% 65% -8% 12% 86%
method. The results are summarised in Table 3. According
to QXRD analysis, the mud mainly consisted of rhodo-
chrosite (MnCO3). The rest contained a 3% of mangan-
osite (MnO) and 47% of amorphous content, however the
composition is unknown.
An Eh-pH diagram generated from HSC system is
given in Figure 4. In this scenario equal molality for Mn
and S at 25 °C was assumed.
Leaching
Mud Leaching
Direct acid leaching with sulfuric acid was performed for
mud. The reaction between sulfuric acid and MnCO3 is
given in Eq.(1). As shown, this reaction produces MnSO4
and releases CO2 gas.
MnCO3 +H2SO4 =MnSO4 +H2O +CO2 (1)
Few preliminary acid leaching tests were performed by add-
ing different acid dosages. Accordingly, in average 2M of
98% H2SO4 acid was used for the mud leaching at room
temperature for two hours. The foaming was significant
and the container size must be large enough to accommo-
date the generated foam during the lab-scale experiments
to prevent foam overflowing. A foam mitigation technique
should be used in bulk lab tests and pilot scale tests. The
average assay results of mud leach solutions are given in
Table 4.
Leach Solution Purification
The purification of resulted leachate from mud processing
will be discussed in the following sections. The presence
of different impurities necessitated multiple purifica-
tion methods to obtain a sufficiently pure solution prior
to MnSO4 crystallisation process. Various precipitation
Table 3. QXRD analysis data of mud
Mineral Mineral Formula Composition
Manganosite Mn(II)O 3
Rhodochrosite Mn(II)(CO₃) 50
Amorphous content Unknown 47
Figure 4. Eh-pH diagram of Mn-S-C system at 25 °C generated from HSC software
Table 4. Mud leach solution assay (average values) and leaching efficiency of different elements
Test Al Ca Fe K Mg Mn Na S Si Sr Zn
Assay, mg/L 1800 500 2350 1800 2000 84500 1200 59000 300 16 1500
Extraction, %56% 10% 32% 95% 91% 84% 65% -8% 12% 86%