Australia, has a production history dating back to 1894. It is located at the southern extent of the Norseman-Wiluna Greenstone Belt in the Eastern Goldfields Province of the Yilgarn Block. The underground mining operations have been primarily based on high grade narrow vein quartz reef mining, supplemented by some open cut mining of lower grade ores. It was recognised in 2014 as Australia’ s longest continually running gold mining operation with 120 years of operation and the extraction of an estimated 5.5 Moz of gold.

Norseman Gold has re-started limited operations including low grade reclaim mining and screening of dumps and stockpile following 10 months of trials at various locations. Ore is treated through the Phoenix mill, which is a conventional gold processing plant( primary crushing, SAG mill, ball mill, gravity separation and carbon in leach( CIL) gold recovery) with a nameplate capacity of 720,000 t / y.

With such a long history of narrow vein high grade underground mining, it is not surprising that in the vicinity of the various mining operations there are extensive surface stockpiles of what was considered, at the time of mining, sub-marginal low grade ore. These stockpiles would have been generated through underground development on-reef in sub marginal ground or from parcels of low grade‘ halo’ ore mined from the highly variable grade

samples obtained from Norseman Gold, initial evaluation confirmed that it was probable that either colour sorting( using the colour difference between the light coloured quartz reef and the darker gangue minerals) or XRT sorting( using the consistent atomic density differential between quartz reef and gangue minerals) would be most likely to achieve effective pre-concentration.

XRT was chosen as the preferred option for evaluation test work, due to the fact that in most applications it is a dry process. The sorter feed does not require washing or scrubbing to remove surface dust or other adherents due to the fact that the absorption signal used to sort individual rock particles is derived from the X-rays passing through the full thickness of the sample. In contrast to this, colour sorting will be affected by surface layers of dust or other materials and typically requires a wet scrubbing process prior to sorting to remove any interfering surface layer. The above is taken from the paper Upgrading low-grade gold ore stockpiles by preconcentration using ore sorting – an assessment of the economic impact and viability by A. N. Parry and G. van Wyk, from the Mill Operators Conference 2016.

In what it describes as“ a huge quantum leap forward,” TOMRA Sorting Mining is now introducing a new multi-channel laser sorting machine which it says“ is destined to set entirely new standards within the industry. Minerals

nuggety reef systems.

One of the major stockpiles comprises low grade run of mine( ROM)

ore extracted from the Bullen, Ajax and St Pats underground mines. The Bullen mine was commenced in 1991 and is accessed via a decline. The Bullen low grade stockpile is situated approximately 2 km from the Phoenix mill. It is estimated that the stockpile contains approximately 1.2-1.5 Mt of low grade ore. No systematic program of mining data review or sampling and assaying has been undertaken in order to determine an

Bits

Rods

Couplings

Shanks

DTH

®

Mining

Construction

Quarrying

Tunneling

Water-well

accurate estimate of the grade profile or an average grade of the

Bullen low grade

®

R o c k M o r e

International

Rock Drilling Tools

Wilsonville, Oregon USA

Judenburg, Austria

Tel + 1( 503) 682-1001

Tel + 43 3572-86300

stockpile. In the case of Bullen low grade stockpile

info @ rockmore-intl. com

austria @ rockmore-intl. com