Anpet Exploration Pty Ltd.

ACN: 079 912 842   -  ABN: 13 079 912 842

PO BOX 625

PENNANT HILLS  NSW  1715

AUSTRALIA

PHONE / FAX: +61 2 9875 5446

Email: anpet@ol.com.au

MEMO

Assessment of Super Sluice Recovery

On 13th July 2001, Graham Bush and I met Martin Marks the Inventor at Oallen Ford on the Shoalhaven River near Nerriga. The site is adjacent to a closed alluvial gold mine that I visited about 14 year ago. The purpose was to assess weather the equipment could live up to the claims made by the inventor, for recovery.

The Shoalhaven river is a large river at this site with a high gradient. There are numerous small gold fields upstream of this locality as well as in the immediate vacuity. Bed of the river at the ford is approximately 80 metres wide with the water restricted at this time of low flow to approximately 10 metres wide. The bedload consists of well rounded cobble to pebble sized material with about 60% sand. Bars vary from cobble dominated to sand dominated, with all variations in between. Individual bars have a length of over 150 metres.

Sites selected for testing were nominated by Marks. The first site was cobble dominated and was logical choice for high gold concentration. The second site was specifically selected by the inventor after a request from me for a fine gold area. I believe that the site would have contained the finest gold present in the system at that locality.

The equipment tested was a very small back packable sluice with adjustable legs, a very small 2 stroke powered pump and layflat hose to deliver water to the sluice. The sluice was fed with a shovel. The sluice was constructed from fibreglass resin, contained built in riffles and was a refined version of sluices that are in widespread use for production and recreational use. The equipment however consisted of an integrated and matched system that was easy to transport, set-up and use.

Approximately 150 kg of gravel with 25% sand was shoveled into the top hutch of the sluice where the spray bar washed the gravel and all but the largest stones (>100 mm) down to the lower hutch where most gold is recovered. Some larger gold remained trapped in the upper hutch. Stones were removed by hand from time to time when the water flow was restricted by blockages. In my opinion the sluice could have been run more efficiently with closer sized feed instead of ROM. This procedure was repeated on a second 150 kg sample from the first site and then the equipment was moved to the fine gold area.

Tailings were systematically checked from the samples with no pannable gold detected in the tailings of the first samples and only one colour of about 0.5 mm detected from the second sample. This compared with recovery of several hundred colours from sample 2 from the first site. Gold size was all less than 1000 micron, with the smallest size seen being about 40~5O micron. Recovery was clearly well an excess of 95%, a remarkable high figure for a sluice grade of the gavels at the first site was estimated at approximately 1.3 g/Au/m.

A sample of about 200 kg was tested from the fine gold site, that had about 50~60% sand and pebbles to about 50~75 mm size. Some problems with excessive water flow were corrected by reducing pump engine speed and sample shoveled in as fast as it could be dug up. Tailings were sampled twice, with the tailings directed into a pan for up to a third of the sample treatment time. The recovered tailings were penned off and about 15 medium and fine colours were recovered. These were flattened and ranged up to about 300 micron in size. Concentrates contained an estimated minimum of 500 colours, with sizes ranging from about 40~50 microns up to 1000 microns (1 mm), with the majority of gold being about 100 micron, considerably smaller than the average size at the first site. The lack of finer gold is probably a function of the river system rather than the capabilities of the sluice as no finer gold could be recovered in careful panning of material from the second site. Minimum size of gold recovered from 10 kg or sample was about 50 micron with a total of approximately 80 colours recovered, ranging up to about 500 microns in size. Recovery is estimated to be in excess of 95% on the second site sample.

Wash up of the sluice was very quick and simple, achieved by washing down the riffles with a small watering can into a pan. In production semi continuous concentrate recovery, without plant shutdown, would be by venturi dumping into a holding lank prior to processing further to recover a higher grade concentrate.

Gold shape tended to be flattened but rough, possibly due to secondary overgrowths of gold on many of the grains. The gold is not as grainy as that at Lalat and consequently better recovery can be expected at Lalat with the same rate of feeding of the sluice.

Recovery by scaled up sluices may not be as good but is expected to still be much higher than traditional design sluices. The robust construction should lead to a relatively Long life, even in a production environment.

The purpose of the assessment was achieved with results surpassing the most optimistic expectations.

Peter Temby

MAIG, MSEG