The nickel deposits on the Beta Hunt Sub-lease are type examples of the Kambalda style komatiite-hosted nickel sulphide deposits. The characteristics of the Western Flanks and A Zone gold deposits are consistent with the greenstone-hosted quartz-carbonate vein (mesothermal) gold deposit model.

Nickel mineralization is hosted by talc-carbonate and serpentine altered ultramafic rocks. The deposits are ribbon-like bodies of massive, matrix and disseminated sulphides varying from 0.5 - 4.0 m in true thickness but averaging between 1.0 - 2.0 m. Down dip widths range from 40 - 100 m and the grade of nickel ranges from below 1 to 20%. Major minerals in the massive and disseminated ores are pyrrhotite, pentlandite, pyrite, chalcopyrite, magnetite, and chromite, with rare millerite and heazlewoodite generally confined to disseminated mineralization. The hangingwall mineralization tends to be higher tenor than the contact material. The range of massive ore grades in the hangingwall is between 10 and 20% nickel while the range for contact ore is between 9 and 12% nickel. The hangingwall mineralogy varies between an antigorite/chlorite to a talc/magnesite assemblage. The basalt mineralogy appears to conform to the amphibole, chlorite, plagioclase plus or minus biotite.

Unlike other orebodies on the Kambalda Dome, the Beta Hunt system displays complex contact morphologies, which leads to irregular ore positions. The overall plunge of the orebodies is shallow in a southeast direction, with an overall plunge length in excess of 1km. The individual ore positions have a strike length averaging 40m and a dip extent averaging 10m. The geometry of these ore positions vary in dip from ten degrees to the west to 80 degrees to the east. The mineralisation within these ore positions is highly variable ranging from a completely barren contact to zones where the mineralisation is in excess of 10m in true thickness.

Gold mineralisation is focussed about the Kambalda Anticline and controlled by northwest trending, steep, west-dipping shear zones associated with re-activated normal faults that previously controlled the komatiitic channel flow and associated nickel sulphide deposition. Gold mineralisation is interpreted as a D3 extensional event associated with porphyry intrusives – the source of magmatic hydrothermal fluids carrying the gold.

Mineralisation is hosted dominantly in Lunnon Basalt (below the ultramafic contact) with minor amounts associated with specific porphyry intrusives. Not all porphyries are mineralised - some are intruded post-mineralisation. The basalt (and porphyries) are preferred mineralisation hosts
as a result of their susceptibility to hydraulic fracturing to form quartz veining, with the migrating ore fluids causing wall-rock alteration. The migrating ore fluids associated with the shearing are interpreted to pass through the overlying ultramafic (because of its ductile nature), developing as mineralisation only where the shear zone passes through more competent rock e.g. porphyry and basalt.

Gold mineralization occurs in three broad, steeply dipping, north-northwest striking quartz vein systems within a sheared biotite-rich, pyritic zone of the Lunnon Basalt. Veining is dominated by shear parallel and extensional vein styles. A Zone and the Western Flanks both occur to the north of the AIF, a major north-northeast trending structure, and is represented by Beta mineralisation to the south of the fault. The Fletcher Shear Zone was discovered by drilling in 2016 and is the third mineralised gold zone at Beta Hunt.

A fourth zone, East Alpha, is inferred by analogy to the known mineralised quartz vein systems, however further drill testing is required to confirm its existence.

Coarse, specimen quality occurrences of gold can occasionally be found where the mineralised shears intersect the interflow sediment horizon and the overlying nickel-bearing basalt/ultramafic contact.

Beta Hunt is a mechanised underground mine accessed from a single decline. The mine commenced operation in 1974, mining both nickel and gold over extended periods. From 2008 to 2014, the mine was on care and maintenance with gold mining commencing in 2015. Currently the mine is producing at a rate of approximately 65,000t per month.

Underground gold mining takes place in two mining areas, the Western Flanks and the A Zone. Western Flanks and A Zone employ a top down, longhole retreat mechanised mining method which suits the subvertical nature of the deposit.

The mine is accessed by portals and a series of declines throughout the mine. The declines are typically 5.5 mW x 5.8 mH, with a standard ore drive size of 4.5 mW x 5.0 mH. Lateral development profiles are well matched to the mobile fleet. Ore is hauled from the underground to surface via the decline where it is then transported via a separate surface haulage fleet to the processing facility.

Top down, mechanised long hole retreat stoping is the mining method used at Beta Hunt. Current stope design dimensions are typically 25m high, vary in width from 2.5 – 25m and 50m on strike. In situ rib and sill pillars are left at geotechnically specified positions, with sill pillars typically left at 75m vertical intervals. Backfilling of stopes is not currently employed in the mine plan.

The typical stope ore cycle post ore drive development is:
- Drilling of blast holes using a longhole drilling rig;
- Charging and firing of blast holes;
- Bogging of ore from the stope using conventional and tele-remote loading techniques;
- Loading of trucks with an LHD;
- Trucks haul ore to surface via the portal; and
- Surface trucks haul ore to the processing facility.

Lateral development drives are excavated using mechanised twin boom jumbos, with vertical development excavated using a production drill rig.

Gold mineralisation is trucked a distance of 78km to the Higginsville Processing Facility using a contracted haulage operator via the Goldfields Highway.

The mill feed is classified and stockpiled according to gold grade to blend an optimal feed mix to the processing facility. Oversize mill feed is sorted from stockpiles and broken on the ROM pad using a loader or excavator. Any oversize that cannot pass through the primary crusher grizzly is broken by a rock breaker.

The crushing circuit has a nameplate capacity of 1.0 Mtpa and consists of four stages of crushing:
- A 36 x 48 Jacques primary single-toggle jaw crusher;
- A 1.68 m Trio Turbocone TC66 (standard configuration) secondary cone crusher;
- A 1.68 m Trio Turbocone TC66 (short head configuration) tertiary cone crusher; and
- A 1.29 m Trio Turbocone T51 quaternary cone crusher.

Crushed material exits the product screen with a P80 of 10mm and is stored in the fine ore bin. The fine ore bin has a live capacity of 1,500t.

Crushed mill feed is withdrawn from the Fine Ore Bin via a belt feeder, which transfers the crushed product onto the mill feed conveyor that feeds into the ball mill. Mill feed can also be fed via an emergency feeder which is fed from the fine ore stockpile via FEL.

The grinding circuit consists of an overflow ball mill, hydro-cyclone cluster classifier and gravity recovery circuit (discussed in the Gravity Recovery functional specification). The ball mill is a LMMP/CITIC-HMC 4.90 m diameter by 6.77 m EGL overflow ball mill.

The crushed mill feed is conveyed to the ball mill feed chute and combined with process water and recirculating cyclone underflow slurry. The ball mill operates in closed circuit with the mill discharge slurry classified by a cluster of hydro-cyclones.

Oversize ore particles and reject grinding balls are rejected from the ball mill discharge slurry by a 16 mm aperture trommel screen connected to the discharge trunnion of the mill. The oversize material (mill scats) is removed from the circuit to protect the cyclone feed slurry pumps and reduce wear rate on cyclone liners and the slurry handling equipment. Mill scats are rejected to a scats bin for removal by wheel loader.

Gold mine production is processed at Karora’s 100% owned Higginsville gold processing facility located 78km south by road.

The processing plant consists of an open circuit jaw crusher followed by closed circuit secondary and tertiary crushers, a fine ore bin, ball mill, gravity separation circuit, one leach tank, and six carbon adsorption tanks.

The primary sections of the processing plant that are currently in use are:
- Crushing and conveying;
- Ore storage & reclaim and grinding;
- Leaching and carbon adsorption;
- Carbon stripping, electrowinning, refining and carbon re-generation;
- Tailings thickening;
- Tailings deposition and storage;
- Reagent mixing and handling; and
- Plant services.

Gravity and Intensive Cyanidation
A gravity separation circuit is included in the design to enhance the recovery of gold that concentrates in the hydro-cyclone underflow stream.

A 100 t/h bleed of the hydro-cyclone underflow stream is delivered to the gravity feed screen for classification. The gravity feed screen is a 1.2m wide by 2.4m long horizontal vibrating screen having an aperture of 3.25mm.

Oversize from this screen will return to the ball mill feed chute for further grinding. Undersize material will report to a centrifugal concentrator to extract the gold. The gravity concentrator is a XD40 Knelson Concentrator.

The resulting concentrate from this process will then be subject to intensive cyanidation in a CS1000DM ConSep Acacia dissolution module to recover the gold. Pregnant solution from the intensive cyanidation process is pumped to the gold room for electrowinning in a CS1000EW ConSep electrowinning module.

Leaching and adsorption
The leach and adsorption circuit consists of one 1,000m3 leach tank and six CIL carbon adsorption tanks, all with a 1,000m3 capacity.

All tanks mechanically agitated with dual, open, down-pumping impellor systems powered by 55kW drives. Facilities are currently available to inject oxygen into tanks #1, #2 and #3 with a high shear oxygen injector pump recirculating into Tank #1.

Leach tank 1 is used as the initial oxidation (oxygen sparged) tank and for the initial dosing of Cyanide. Slurry flows from this tank into the carbon adsorption circuit.

Gold that is dissolved into the cyanide leach solution is recovered and concentrated by adsorption onto activated carbon (Haycarb) in the adsorption tanks.

Cyanide solution at 30% strength by weight is added to the leach tank feed distributor box and/or the first CIL tank via a flow meter and automatic control valve. The design leaching residence time is 5 hours.

Discharge from the leach tank will overflow into the first of six 1,000m3 CIL tanks (tanks 2 to 7) which have an average effective working volume of 984m3 each. The combined adsorption residence time is 30 hours.

In the CIL tanks, the carbon is advanced counter-current to the slurry flow, with new and regenerated carbon added to the last tank and advanced to the first tank while the slurry flows from tank one to tank six. Loaded carbon is pumped from adsorption tank one to the gold room elution circuit periodically for stripping of the gold.

Carbon stripping, electro-winning, refining, and carbon regeneration
Gold is recovered from the loaded carbon by a Pressure Zadra electro-winning circuit. Gold is deposited onto steel wool cathodes by the electro-winning cells. The cathodes are subsequently dried and smelted in the gold room barring furnace to produce gold bullion for shipment.

The gold from the gravity circuit is leached in the Acacia reactor and it is then electroplated by the Acacia electrowinning circuit. Steel wool cathodes from the Acacia cell are smelted in a similar manner to the gold produced by the Pressure Zadra circuit.

Barren carbon is reactivated using a liquid natural gas (LNG) fired vertical kiln at around 700°C prior to being returned to the adsorption circuit for reuse.