Spiking Tracer Testing

Spiking tracers are most commonly used in plants which process liberated diamonds from alluvial deposits. They are designed to test the ability of a circuit to direct diamonds to density separator concentrate. They have density 3.53 g/cc and they luminesce brightly so there is little likelihood of any being lost to sorter rejects.

On the face of it, testing is easy!

For example:

1. Ten 8mm spiking tracers are selected.
2. Their colour is green. This can be used as an indicator of where in the plant they are to be inserted.
3. They are inserted in the mixing box for DMC Module 2.
4. Recovery schedules indicate that all should be collected at the glovebox within 36 hours.
5. After 36 hours, nine 8mm green tracers have been retrieved at the glovebox.
6. The efficiency of Module 2 in recovering 8mm (9 carat) diamonds is estimated as 90% (9/10 x100).

But one really should consider the statistics of the situation. We have conducted 10 Binomial Trials (experiments with only 2 possible outcomes.) For 9 of our experiments the outcome was "success”. There are numerous online calculators to help us estimate the underlying probability (that diamonds of that size will report to the X-ray sorters). View Calculator

Our estimate of the probability was 90%, and the statistics tell us that we can be 95% confident that our diamond recovery rate is greater than 57%.

You mean that circuit may be discarding 43%
of my diamonds!!

Better to use more tracers. If you insert 1000 and recover 900, you can be 95% confident that you are recovering at least 88% of the diamonds. The calculator also shows that you can have 95% confidence that you are losing at least 8% of them.