The appropriate amount of a sample is weighed on an analytical /Top pan balance , mixed with lead collection flux to a consistent mix and loaded into a fusion furnace at 1180 to 1220oC for 45 - 75 minutes(concentrates and /or Feed & tails). This is done under reducing conditions. The PGM’s and gold will be collected in the lead button. The slag from lead button is removed by a de-slagging machine.
The lead button, after being de-slagged into a round form, is loaded into a cupellation furnace at 1 024oC for an hour. The lead will be absorbed by the cupel and some is oxidized in the presence of atmospheric oxygen in the cupellation furnace. When the cupellation is complete the PGMs & Au and Ag prill will be left on a hollow surface of the cupel.
High Temperature Cupellation
After the cupellation stage, the silver, PGMs and Au is transferred into a 30-hole block cupel, lead shot is added (±2mg) and loaded into a high temperature furnace at 1325⁰C for 1, 5 hours. It is then removed, left to cool and prills weighed on the micro balance and a calculation done to determine the PGM concentrations.
Fire assay with gravimetric finish
- Sample prep.
- Wet and dry screening.
- SG Determination.
- Moisture Analysis.