In the gold mining process, there is a tendency to switch from the cyanide leaching process to the thiosulfate leaching process due to the reduced toxicity of the thiosulfate leaching.
However, the thiosulfate leaching process is sensitive and demands more optimization of the leach reaction components to maximize gold recovery and reduce reagent loss. A Metrosep A Supp 5 - 250/4.0 column is used to separate tetrathionate, thiocyanate, thiosulfate, and sulfite with perchlorate as the eluent as most of the metal perchlorates are water-soluble, thereby avoiding metal precipitation within the IC system.
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Sample
Mining leachate
Sample preparation
Dilution 1:2 in ultrapure water, injection following filtration (0.45 μm).
Columns
| . |
. |
| Metrosep A Supp 5 - 250/4.0 |
6.1006.530 |
| Metrosep A Supp 4/5 - Guard/4.0 |
6.1006.500 |
Solutions
| Eluent |
10 mmol/L sodium perchlorate
1.0 mmol/L sodium hydroxide |
Analysis
UV/VIS detection
Parameters
| . |
. |
| Flow rate |
0.7 mL/minute |
| Injection volume |
20 μL |
| Pmax |
15 MPa |
| Recording time |
32 minutes |
| Column temperature |
35 °C |
| Wavelength |
215 nm |
Instrumentation
| 940 Professional IC Vario ONE |
2.940.1100 |
| 944 Professional UV/VIS Detector Vario |
2.944.0010 |
| 858 Professional Sample Processor |
2.858.0020 |
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Image credit: Metrohm
Results
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Image credit: Metrohm
| Anions |
Concentration [mg/kg] |
RSD [%, n = 3] |
| 1 |
Sulfite |
< 1 |
- |
| 2 |
Thiosulfate |
58.8 |
2.2 |
| 3 |
Thiocyanate |
49.7 |
1.9 |
| 4 |
Tetrathionate |
28.6 |
1.4 |
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This information has been sourced, reviewed and adapted from materials provided by Metrohm AG.
For more information on this source, please visit Metrohm AG.