The challenge is to develop a process for accurate determination of gold purity which will be non-destructive and at a depth >10 µm.
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 a 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 a faster alternative to detect the purity of gold. It takes only a couple of minutes for the 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, the XRF technique can not be continued as a long-term alternative and needs to be replaced with a better system. Therefore, we seek suitable environmental-friendly and non-destructive based solutions to resolve the challenges, as described above.
LIBS, PGNAA are interesting approaches, but much is in the research stage and requires extra safety precautions.
Expecting a table top equipment which is reliable and mountable on a conveyor and which can be automated for easy and quick checking.