The Xcentric Ripper has been fitted to a 30t excavator. It is designed to increase productivity by using a vibrating tip instead of a conventional percussive hammer.
The vibrating nature should also reduce overspray of rock "fly" material normally associated with a standard percussion hammer.
The Xcentric Ripper is made by Xcentric Ripper Australia, a Sydney company.
Once the initial trench is completed, detailed and systematic metal detection with geological mapping will be geological mapping will be done before bulk sampling of small 50kg to 500kg samples begins.
The aim is to assess the gold potential of the conglomerate units as quickly and efficiently as possible with sufficient detail to allow De Grey to commit to more costly larger tonnage sampling of up to 2t with long lead time processing at an independent laboratory.
De Grey's sampling plans include:
- Geological mapping that aims to determine the contacts of the prospective conglomerate unit relative to the underlying Mallina sediments and the overlying Mt Roe basalt;
- Metal detecting across the geological units with locations plotted for future assessment and as a guide to the more prospective horizon or horizons;
- Bulk sampling, which will initially comprise samples ranging 50kg to 500kg taken from the various lithologies and will be processed on site by De Grey staff; and
- Large bulk samples of up to 2t to be taken systematically across and along the trenches where deemed appropriate based on information from the previous steps.
To carry out the on-site sampling De Grey has established a small crushing and gravity processing circuit, which will be used to assess the 50kg to 500kg samples.
This custom-built processing circuit has a jaw crusher to reduce the conglomerate material to less than 20mm particles.
Those particles will be scanned by a hand-held metal detector to remove detectable nuggets and nugget bearing rock fragments.
The crushed material will then pass through a hammer mill, which will reduce particle size to less than 1.2mm.
The second pass crushed material will then be fed through a Knelson concentrator with the heavy mineral concentrates passed over a gold jig table to produce a gold-rich concentrate.