Mining and Metallurgy Sample Probes — Hydrometallurgy, Smelter, and Slurry
Sample probe assemblies for mineral processing: leach circuits, SX-EW, smelter gas, autoclave, and CIL/CIP cyanide leach. Material selection for chloride, sulfate, and cyanide service.
Overview
Mineral processing combines aggressive chemistry, high temperatures, abrasive slurries, and large-bore vessels. Sample probes must handle pregnant leach solution (PLS), raffinate, slurry, and high-temperature smelter gas — sometimes in the same plant.
Process-by-Process
| Process | Service | Material |
| Heap leach pad | Sulfate PLS, low temperature | 316L or duplex |
| Tank leach | Cyanide + slurry | 316L |
| CIL / CIP gold | Activated carbon slurry + NaCN | 316L |
| SX-EW (copper) | Strong acid PLS | Alloy 20 / Hastelloy C276 |
| Pressure oxidation | Hot acid + chloride | Titanium Gr 2 / Hastelloy C276 |
| HPAL autoclave | Hot acid + Ni/Co | Titanium Gr 12 |
| Flotation cell | Slurry + collector | 316L |
| Smelter offgas | Hot gas + SO2 | Inconel 625 + ceramic liner |
| Acid plant (H2SO4) | Hot H2SO4 | Tantalum or Alloy 20 |
| Tailings | Slurry + residual reagent | 316L |
Slurry Handling
Mineral slurries are abrasive. A standard cantilever sample probe will erode at the inlet within weeks. Mitigations:
- Sacrificial wear sleeve at the tip
- Tungsten carbide hard-faced inlet
- Chrome-carbide overlay on the wetted shank
- Larger ID to reduce velocity at the inlet
- Schedule the probe for replacement at fixed intervals per the cycle life schedule
Pressure Oxidation Autoclaves
Autoclave conditions — 200 °C, 500 psig, sulfuric acid + chloride + dissolved metals — destroy nearly every CRA. The standard material is titanium grade 2 (or grade 12 for additional crevice corrosion resistance), with all-welded construction and no compression fittings on the wetted boundary.
Cyanide Leach Considerations
Cyanide leach circuits (CIL/CIP) are mildly alkaline (pH 10-11) and not particularly corrosive. 316L is standard. The bigger concern is cyanide carryover into the analyzer, which is solved by aggressive sample line flushing per the time-delay reduction guide.
Configurator Defaults
When the user selects "mining / metallurgy" in the SPA Configurator, the wizard asks for the specific unit (leach, SX, autoclave, smelter, etc.) and tunes the material recommender accordingly.