I am presuming that the material is zircon and zirconia concentrates? I am also presuming that the concentrates are naturally occurring and are powders or sands? For example, heavy mineral concentrates from beach sands. If these assumptions are correct then there is the potential for the material to vary widely in composition depending on the source. For example, zircon from a pegmatitic source may have 10x the uranium content of the associated granite.

Initially, for this sort of material, you need to invoke a thorough and rigorous sampling procedure before any analysis!

When I worked for the CSIRO in the 1990's we used to use a digestion in high purity Hf (bottle to bottle still) in a hydrothermal bomb at 180oC, overnight, but we only used ~200mg of material. Analysis was done by thermal ionisation mass spectrometry after column separation.

A technique I helped pioneer at Macquarie University in Sydney was to fuse the sample into XRF discs and analyse the disc using ICP-LA-MS.

Analysis by these methods is expensive though they are very sensitive and produce excellent data.

I reiterate great data is useless if the sampling method is poor.

Thank you Stephen! Exactly what I had hoped to read. We did ICP-LA-MS, on top of ICP-MS with HF digestion/dissolution (but we got Fluoride precipitates). We also did XRF fused beads (and yesterday i checked and found undigested material in those beads). So the ICP-MS and XRF values are low....The LA results are twice as high as the other two results (and I know those are poor due to undigested or precipitates). I'm trying to explain to engineers that they cannot throw out the ICP-LA-MS...a tough road. The analysts are sure the problem is inhomogeneous samples.... thank you

Hi,

in my opinion the measurements of Uranium-238, 234 and 235 and Th-232, Th-228 may be performed using the alpha spectrometry after radiochemical sample treatment.

In particular applying the wet or microwave dissolution sample with Tracer adding (such as U-232) and separation of Uranium and Thorium by ionic resin or specific extraction resin, electrodeposition and measurements by alpha spectrometry.

With this method, you could have a very low MDA, some mBq/kg.

You could take like a suggestion the ASTM C-1000 Standard Test Method for Radiochemical Determination of Uranium Isotopes in Soil by Alpha Spectrometry or other technical documents, such as the IAEA method or paper.

Best Regards

Thank you very much Mattia!

I think using spectrometry!

Thank you Mohammad.