Kanowna Belle is located in the Kalgoorlie Terrane (Boorara sub-domain) of the Eastern Goldfields Province. Stratigraphically, the deposit sits in the Black Flag Group which overlies the lower volcanic sequences.

The Kanowna Belle deposit is hosted within a series of volcaniclastic sediments ranging in grain size from shale to conglomerates. These rocks are respectively separated into hangingwall and footwall sequences by a major 60° S-SE dipping zone of structural disruption and mineralisation.

The footwall sequence is dominated by the Golden Valley conglomerate, a mafic-dominated unit interbedded with the felsic-dominated Cemetery conglomerate. The hangingwall sequence comprises three main volcaniclastic units, these are the QED rudite, the Lowes sandstone and the Grave Dam grit, which is the dominant unit.

The sequence has been intruded by the Kanowna Belle porphyry, which is granodioritic in composition. At least 70% of the known gold mineralization is hosted by the Kanowna Belle porphyry, with the remaining mineralisation hosted by sedimentary units.

The Kanowna Belle deposit is controlled by the Fitzroy Fault Zone and associated splay structures. The Fitzroy Fault has been interpreted to be a reactivated D1 thrust ramp. These deformation events have been categorized on the Fitzroy Fault into three distinct styles (and thus deformational stages):
- Fitzroy Mylonite;
- Fitzroy Shear Zone;
- Fitzroy Fault.

These events have produced clear structural overprinting relations and have localised the emplacement of the Kanowna Belle porphyry.

Mineralisation at Kanowna Belle occurs in both supergene enriched horizons in the near surface environment (oxidised to transitional material) and at depth in primary fresh rock sulphide hosted gold. The primary mineralisation at Kanowna occurs in discrete ‘lodes’ or ‘shoots’.

Weathering over the Kanowna deposit is typically to a depth of 70m across the deposit, and is characterised by saprolitic clays.

A zone of supergene gold enrichment is located above the Kanowna Belle deposit in a thin variably developed blanket over a 600m by 250m area. The supergene enrichment zone typically occurs 35m above the primary deposit at the transition between completely oxidised and transitional material.

The Lowes Shoot is the main zone of mineralisation in the mine. It hosts 80% of the total resource and is characterised by a consistent ore grade of 4gpt across its width, with areas of higher grade being sub-parallel to the FSZ or the orientation of the regional cleavage. Mineralisation in the Lowes shoot is characterised by micro-fracturing, abundant quartz carbonate-pyrite veins and minor secondary breccias. Quartz-sericitecarbonate-pyrite breccias also occur parallel to major structural zones.

Two overprinting temporally and mineralogically distinct mineralisation events are recognized in the Kanowna Belle Deposit:
- An early high level (epizonal) Gold-Telluride mineralisation event;
- Later Pyrite associated mineralisation.

In the Gold-Telluride phase of mineralisation, gold occurs as blebs of free gold in association with Telluride minerals. The most common telluride minerals observed are Altaite (Lead Telluride), Coloradoite (Mercury Telluride) and Melonite (Nickel Telluride). Texturally the gold-telluride mineralisation occurs as microfracture and microvug infill. Volumetrically, this phase of mineralisation accounts for less than 10% of the gold endowment at Kanowna Belle.

Gold in this mineralisation phase occurs mostly as fine grained (less than 10 microns (µm)) inclusions in pyrite or as very fine-grained gold located in arsenic rich growth zones in pyrite. Free gold occurs in minor proportions, and typically occupies D2 extensional sites adjacent to pyrite crystals.

Mineralisation also sits in the Velvet deposit, 500m west of the main Lowes deposit and 600m below surface. Gold mineralisation at Velvet is hosted within an intrusion of intermediate composition that broadly follows a sub vertical hanging wall splay of the Fitzroy Shear Zone. The splay structure, locally termed ‘Velvet Mylonite’, is characterized by a well-developed porphyroclastic fabric and is separated from the Fitzroy shear Zone by a zone of massive carbonate (mainly dolomite) breccia. Gold is also typically fine grained, with two different mineralisation styles at Velvet also existing.

- Earlier sulphide with iron dolomite alteration.
- Carbonate breccia with sulphide stringer veins and coarse gold veins.

Typical ore assemblages contain 0.5 to 1.5% sulphur and 40ppm arsenic. Kanowna Belle ore is generally refractory, meaning that oxidation (i.e. roasting) is required to maximise gold extraction. The Pyrite associated mineralisation provides the majority of gold produced from the Kanowna Belle Orebody.

The near-surface weathered portion of the Kanowna Belle deposit shows significant gold depletion to at least 35m above an undulating supergene “blanket” horizon. This mineralised supergene “blanket” had pre-mining plan dimensions of 600m strike x 250m across strike and a thickness of between 1m and 10m.

The main Lowes shoot has a strike length of 500m, width of 5m to 50m, and a down-plunge extent greater than 1,250m.

Hanging wall shoots have a maximum strike of 240m, width of 2m to 10m and a current down plunge extent of no more than 800m.

Footwall shoots have a maximum strike of 240m, width of 2m to 20m and a current down plunge extent of no more than 700m.

The Kanowna Belle gold deposit is mined by longhole stoping and underhand longhole bench stoping with paste fill methods. This mining method was selected to minimise the impact of mining induced stress on the underground operations by geotechnical driven mining sequences and a fill system integral in the mining cycle.

The mining method used at Kanowna Belle underground is called longhole open stoping (LHOS). Mining of the LHOS commences with the development of drives (tunnels) on each level and the sides of these are supported by cement grouted roof bolts, mesh and shotcrete. These drives delineate the boundary of the stope. Each LHOS is 15-30m wide, up to 50m long and 120m high. Depending on size each stope may contain between 20,000 to 50,000 tonnes of ore.

The Kanowna Belle gold mine has been extracted down to a depth of 1,301m below surface with a possible extension into lower E block, further development of the Troy and Sims loads located in the hangingwall, higher in the mine. The Velvet deposit sitting 500m west of the main Lowes ore body is also a substantial part of the production and open a depth.

All mining operations are operated by NSMS, excluding diamond drilling which is contracted.

The crushing and grinding circuits are common for the free milling and refractory circuits.

The crushing circuit is a simple single stage circuit with a 240t capacity ROM bin feeding a Jaques double toggle 60x48 (185kw) crusher at a 420tph crushing capacity. The crushed ore, nominally minus 125mm reports to a 20,000t partially-covered coarse ore stockpile with a live capacity of about 1,000t.

This product is then reclaimed by an apron feeder and two vibrating feeders located under the stockpile and discharged onto a conveyor belt. The crushed ore is then conveyed to the grinding circuit.

The grinding circuit comprises an ANI Products 7.32m x 3.35m SAG mill operating in closed circuit with a Metso Nordberg HP200 recycle cone crusher and an ANI Products 4.72m x 7.01m Ball mill in closed circuit with cyclones. The SAG mill has a grate discharge and is steel lined, while the Ball mill has a trommel screen discharge and is rubber lined. The SAG mill has a variable speed drive with a range of 10 to 12 rpm, while the Ball mill has a fixed speed drive at 14.0 rev/min (72% of critical). The installed power for the SAG and Ball mills is 2,850kW. The grinding circuit throughput is currently around 240 – 250tph.

The Kanowna Belle processing plant is a complex and versatile plant that includes separate circuits for processing free-milling and refractory gold ores. The plant has undergone progressive upgrades since its initial construction and now has an annual throughput capacity of approximately~ 2Mtpa of hard rock underground ore.

Pre-leach classification is achieved using a hydro-cyclone classifier circuit consisting of a cluster of 18 x 250mm cyclones that are fed from a central distributor. Only eight to nine of the cyclones are operated at any one time depending on volume of slurry in the milling circuit. Three of the cyclones in the cluster are dedicated to feed the Knelson gravity concentrator during the free milling ore campaigns. The cyclones are operated at a feed pressure of 110-130kpa.

For the free milling ore, the cyclone overflow stream reports directly (via a vibrating trash creen) to a 17m diameter high rate thickener. For the refractory ore, the cyclone o ........