Season 3 Challenges

Ferous Oxide

Among several characteristic tests, Karatage checking of gold for its purity is critical, since gold ornaments are valued based on its purity and weight. It has always been a challenge to exactly measure the purity of the gold alloy. To assure proper Karatage to the gold, purity checking has been carried out as an integral part of various stages of operations. In this context, fire assay (FA), a well-known high temperature furnace method, technique has been followed to determine assay or purity of gold with an accuracy of ±0.02wt%. However, the process demonstrated by FA​ is destructive and highly time consuming with the required process time of 4h for complete set of operations. Hence, we can expect considerable dip in the production rate and inventory flow because of lengthy and complicated test procedures. In this endeavor, XRF (Karat Meter) technique, a non-destructive technique, was used as faster alternative to detect the purity of gold​. It takes only couple of minutes for XRF technique to complete the checking of Karatage of gold. However, due to poor tolerance of ± 0.5wt% and inability to measure the surface beyond the depth of 10 μm, XRF technique can not be continued as long-term alternative and needs to be replaced with the better system. Therefore, we seek suitable environmental-friendly and non-destructive based solution to resolve the challenges, as described above.

  • Options tried to solve before:

LIBS, PGNAA are interesting approaches, but much is in research stage and requires extra safety precautions.

  • Future State:

Expecting a table top equipment which is reliable and mountable on a conveyor and which can be automated for easy and quick checking.

  • Success criteria:

  1. The test to be conducted in few seconds.
  2. The tolerance should be comparable with fire assay which is ±0.02wt%.
  3. Purity needs to be checked beyond the depth of >10 μm on the surface.

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