Safe digestion of Sulphide Ores

The digestion of sulphide ores for analysis by AAS ,ICP or ICP-MS creates two potential problems.

  • 1.  Sulphide ores can contain silicates which are difficult to digest by aqua regia and require use of HF which requires special handling and safety precautions. 
  • 2. Sulphides can generate large quantities of SO2 which has to be allowed for in sample weigh-ins.

In a conventional microwave digestion, the combination of these two problems can be a dangerous procedure with  HF vapour being released into the microwave cavity and also the laboratory atmosphere if a vessel should burst the rupture disc.

The Berghof SP4 is specifically designed to safely digest this problematic ore with the following features:

  • 1. Each vessel  has its own pressure monitoring sensor which has a feedback mechanism to reduce pressure. The contactless sensor is embedded in the vessel cap. For more details refer to diagram.




  • 2. In the event that the pressure sensor feed back is unable to control the rapid pressure increase, then there is an additional fail-safe feature to ensure that any dangerous gases are collected and correctly vented into a fume cupboard.

              Each vessel is connected to a manifold that in turn has it's own vent tube. Refer to diagram.



This ensures that HF gases are not released into the microwave cavity and damaging the circuitry and importantly not allowing the vapours to enter the laboratory area.

A typical digest mix would include an acid mix of:

       HC l: HNO3 : HF in a ratio  of 5 : 2 : 2 . with an excess of HCl.

Sample weigh-in would be  1-1.5 gms  with temperature to 220 Deg C and pressure to 40 bar.