Tampia (Narembeen)

Location & Project History

The Tampia gold project has been acquired via the takeover of Explaurum Limited (ASX:EXU) by Ramelius in late 2018 / early 2019.

The project is an undeveloped gold project located 12km south-east of the town of Narembeen in the Western Australia wheatbelt and 250km east of Perth.

The deposit is 148km by sealed roads from the Edna May gold mine.  The deposit is located on granted mining lease M70/816.  The total project area covers 327km², comprising two mining leases and nine exploration licences.

Geology and Mineralisation

The deposit is hosted within a highly metamorphosed mafic gneiss unit.  The mafic gneiss contains migmatitic feldspar-biotite-quartz banding within an overall synformal structural trend.  It is also intruded by granitoid dykes and sills.

Mineralisation occurs as shallow dipping stacked tabular lodes within the mafic gneiss.  These lodes are approximately parallel to the overall mafic gneiss unit geometry, banding and synformal structure. Granitic sills are intruded sub-parallel to lodes and are late and unmineralised.

Gold mineralisation is associated with hornblende-biotite-pyroxene-plagioclase alteration and disseminated arsenopyrite-pyrrhotite-chalcopyrite sulphides.  Gold mineralisation correlates strongly with Arsenic grade and fresh ore is partially refractory.  Weathering is relatively shallow.

Mineralisation currently extends over a strike length of 700m.  The tabular lodes are between 2 and 20m thick with a drilled down-dip extent of around 350m.  Between 1 and 3 economic lodes generally occur per drill section.

Explaurum Ltd completed a significant 40m x 40m spaced resource drilling programme in 2017 and generated a Feasibility Study in May 2018.

Refer to EXU ASX release ‘Tampia Feasibility Confirms Robust High-Margin Gold Project’, 30 May 2018 for full details.

The deposit is augmented by the small Mace paleochannel deposit.  The deposit hosts re-mobilised, frequently nuggetty gold, in a 10 to 50m wide, 2 to 6m thick paleochannel zone occurring 10-15m below surface.  The channel starts over the main Tampia deposit and extends north-west for 550m. Gold is hosted by clays and the base of the channel marked by semi-rounded quartz fragments.  While not large, the Mace deposit represents a low-strip, free milling, high-margin ore source.

Tampia drillhole plan with RMS 2019 infill (blue holes)

Mineral Resource

Since completion of the last resource, Explaurum drilled a further 133 close-spaced ‘grade control’ RC holes at the core of the deposit.

The project financials are calculated on Ore Reserves only and are shown on a 100% basis. The Tampia project is 90% owned by Ramelius along with a 10% minority holder who is free-carried until a decision to mine is made.

Metallurgy 

The original processing method incorporated gravity recovery, flotation, ultra-fine grinding, and enhanced leaching to treat the more refractory elements of the ore, with carbon-in-leach (CIL) being used to treat the flotation and enhanced leach tailings product. Subsequent testwork on this flotation and ultrafine grind process demonstrated that cyanide consumption and hence recovery was adversely affected by the fine grind liberation of the pyrrhotite minerals. Additional test work was conducted on spatially representative ore samples, which included the more refractory elements of the ore. This additional test work demonstrated that at a range of reduced grind sizes (75µm, 106µm and 125µm), the standard gravity and CIL process is equally effective, if not superior, to the initial proposed flotation and ultra-fine grind processing at arsenic levels up to 5,000ppm. Resource modelling indicates less than 15% of the gold in the Tampia ore to be associated with arsenic levels greater than 5,000ppm.

The revised milling process for Tampia uses a simpler, more conventional gravity recovery and CIL process at a moderately finer grind size of 125um. Capital costs for the Edna May processing facility have reduced from $35M to $7.5M and operating costs are reduced from $25/t down to $22.47/t.

Ore Reserve

The project financials are calculated on Ore Reserves only and are shown on a 100% basis. The Tampia project is 90% owned by Ramelius along with a 10% minority holder who is free-carried until a decision to mine is made.

Tampia Resource model and open pit design