MODEL: FPA - FLUORESCENT PARTICLE ANALYSER

wavelength thus making it possible to distinguish them from diamonds by means of optical filtering.

The magnitude of fluorescence of such ‘interference’ minerals is determined by much the same criteria as listed for diamonds above.

There are concentrates that are ideally suitable for X-ray-based diamond recovery machines i.e. the material to be sorted contains only “well-fluorescent” diamonds and it contains no other fluorescent (interference) minerals!

On the other end of the scale, the material to be sorted contains “low-fluorescent” diamonds as well as a high percentage of other fluorescent (interference) minerals. (In the worst case such ‘interference’ minerals fluoresce at a similar wavelength as a diamond!)

However such extreme cases are seldom found in practice. In reality, diamond concentrate characteristics lie somewhere in-between.

Diamond concentrates properties however do also often vary a lot even if they originate from the same area.

To achieve a good and consistent diamond recovery with an X-ray-based sorter it is important to recognize and understand the properties of the concentrate to be sorted and to set up an X-ray diamond recovery machine accordingly.

Optimizing such a sorter setup requires experience and a solid understanding of X-ray diamond recovery principles.

The operator often blames poor diamond recovery on a ‘faulty sorting machine or claims that the diamond that was not recovered by an X-ray sorter is not fluorescing! (the latter being very rare indeed)

A typical cause of poor diamond recovery is that the operator reduces the sensitivity of the sorter optic system so that the machine does not eject ‘too much’ material as otherwise there is too much material for hand sorting!

What he has achieved is that by lowering the sorters optics sensitivity many of the ‘interference’ minerals are no longer being ejected to concentrate but at the same time the weaker fluorescent diamonds are also no longer recovered!

With the help of an FPA, all this guesswork be avoided.

Fluorescent levels of Diamonds, as well as the fluorescence of any other mineral present in sorters feed material, can be measured.

An optimum X-ray recovery machine setup can be established. The expected yield and optimal feed rate can be calculated etc.

Actual fluorescent levels of particular diamonds can be accurately measured.

The effectiveness of optical filters can be established.

Our FPA is also a very useful tool when it comes to measuring the fluorescent properties of tracers. The FPA can be used to sort tracers into various fluorescent intensity categories which in turn makes tracer tests much more meaningful.

The conclusion from the above is that for the professional, serious user of

X-ray diamond recovery machines a Fluorescent Particle Analyser is a very important and useful tool.

For a mine operating a single Flow Sort machine, it is difficult to justify the cost of an FPA (unless it is used for delicate exploration or sampling work). For mining houses that operate multiple Flow Sort machines at different sites and under changing conditions, an FPA is a must. Our FPA is transportable and can therefore serve many different mining sites.

It is the only way to quickly establish facts about various concentrates and so provide the necessary information which is needed to optimize the performance of Flow Sort X-ray diamond recovery machines in the field.

We, at Flow Sort had several requests to develop such an analysing tool to add it to our product range. Well, now we have done so and the first production run has been sold before production has commenced!

Peter Wolf

P.S.    Please also note that our FPA is also useful for on-site testing of Photo Multipliers as well as X-ray tubes.

As our FPA utilizes essentially the same components as our XR machines there is no need for any extra spare part holding.