Overview

Deposit type

• Vein / narrow vein
• Magmatic
• Mesothermal

Summary:

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. Beta Hunt is situated within the central portion of the Norseman-Wiluna greenstone belt in a sequence of mafic/ultramafic and felsic rocks on the southwest flank of the Kambalda Dome. Gold mineralization occurs mainly in subvertical shear zones in the Lunnon Basalt and is characterized by shear and extensional quartz veining within a halo of biotite/pyrite alteration. Within these shear zones, coarse gold sometimes occurs where the shear zones intersect ironrich sulphidic metasediments in the Lunnon Basalt or nickel sulphides at the base of the Kambalda Komatiite (ultramafics). Nickel mineralization is hosted mainly by talc-carbonate and serpentine altered ultramafic rocks (Kambalda Komatiite) that overlie the Lunnon Basalt. The primary sulphide minerals are typically pyrrhotite > pentlandite > pyrite with trace chalcopyrite. Nickel Mineralisation Nickel mineralisation 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 m to 4.0 m in true thickness but averaging between 1.0 m and 2.0 m. Down dip widths range from 40 m to 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 mineralisation. The hangingwall mineralisation tends to be higher tenor than the contact material. The range of massive ore grades in the hangingwall is between 10% Ni and 20% Ni while the range for contact ore is between 9% Ni and 12% Ni. 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. The overall plunge of the deposits is shallow in a southeast direction, with an overall plunge length in excess of 1 km. The individual lode positions have a strike length averaging 40 m and a dip extent averaging 10 m. The geometry of these lode positions vary in dip from 10° to the west to 80° to the east. The mineralisation within these lode positions is highly variable ranging from a completely barren contact to zones where the mineralisation is in excess of 10 m in true thickness. The Hunt and Lunnon shoots are separated from the Beta and East Alpha deposits by the Alpha Island Fault (AIF). Hunt and Beta both occur on the moderately dipping western limb of the Kambalda Dome and are thought to be analogous. Similarly, Lunnon and East Alpha occur on the steeply dipping eastern limb of the dome and also have similar characteristics. Gold Mineralisation 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 mineralisation occurs in three broad, steeply dipping, north-northwest striking quartz vein systems within biotite-albite-pyrite altered shear zones hosted by 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. A Zone Gold mineralisation in A Zone is located below the A Zone nickel surface and is composed of a large brecciated quartz vein that has a near vertical dip striking at 320°. A Zone varies in thickness from 2 m to 20 m wide with a low to medium grade distribution. The A Zone shear is mineralised over approximately 1.5 km of strike length with the northern portion containing the higher grade and greater thickness. Subparallel mineralised structures are found in both the hangingwall and footwall to the main A Zone shear. Western Flanks Mineralisation comprises a main, northwest striking (320°), steep southwest dipping shear zone up to 20 m in width, over 1.2 km in strike length with a 500 m down-dip extent and remains open to the north and down-dip. Coarse “stockwork” mineralisation dominated by shallow, east-dipping extensional quartz veins occur in the hangingwall of the main shear. The combined main shear and hangingwall mineralisation can, in places, be up to 50 m thick. The main shear zone consists of both shear and extensional veining associated with biotite-albite-pyrite alteration. Mineralisation within the hangingwall is characterised by a lack of shearing and shear veins. Extensional veins in the hangingwall frequently contain specks of visible gold. The shear zone is dextrally offset to the south by the Alpha Island Fault. Felsic porphyries strike oblique to mineralisation and zones of high grade are found along the margins where they are adjacent to or host mineralised structures. This style of mineralisation is intermittently found associated with the A Zone, Western Flanks and Beta mineralisation zones, where the mineralised shears intersect iron sulphide-rich contacts represented by the main basalt/ultramafic contact and pyritic interflow sediment (A Zone). Mineralisation in the Beta Block, which includes the new Larkin deposit, is interpreted to be an offset extension to the Western Flanks and A Zone mineralisation, with a dextral offset of between 100 m and 150 m. Beta is again characterised by a series of subvertical quartz veins within a sheared basalt. Mineralisation at Beta has a more disjointed and erratic form, with narrow discontinuous lodes that have a strike extent of 20 m to 100 m. Lodes vary in thickness from 1 m to 5 m, commonly with high grades being present on the contacts of porphyries and ultramafic.

Mining Methods

• Longhole stoping
• Room-and-pillar
• Cut & Fill
• Airleg stoping

Summary:

Beta Hunt Gold Operation
Beta Hunt is a mechanised underground mine accessed from established portals and declines. The mine is producing at a rate of approximately 100,000 t/month ore. Gold mine production is processed at Karora’s 100% owned Higginsville and Lakewood processing facilities located 78 km by road to the south and 61 km by road to the north, respectively.

The mine is accessed via established portals and declines. Pumping, ventilation, power and mine service infrastructure is established and in use for current mining operations.

Underground gold mining currently takes place in two mining areas, the Western Flanks and the A Zone, with planned mining of the Larkin deposit within the next year. The strike of the A Zone and Western Flanks totals approximately 1,500 m, with stoping occurring over a total vertical extent of approximately 500 m. Western Flanks and A Zone employ a top down, longhole retreat mechanized mining method which suits the subvertical nature of the orebody. Mining at Larkin will also utilise the same mining method.

In situ rib and sill pillars are left at geotechnically specified positions, with sill pillars typically at 75 m vertical intervals.

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 5.0 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.

The primary mining method used at Beta Hunt is top down, mechanised long hole retreat. Current stope design dimensions are typically 25 m high, vary in width from 5.0 m to 25 m and up to 50 m on strike. In situ rib and sill pillars are left at geotechnically specified positions, with sill pillars typically left at 75 m vertical intervals. Waste is used to backfill voids where possible. No other methods of backfilling stopes is 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 a load-haul-dump (“LHD”) loader;
• 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 raisebore drill rig.

Site performance has ramped up recently to 100 kt/month, made possible with an increase to the mining fleet size. Karora is targeting a 100 kt/month production rate which is underpinned by the 2022 Mineral Reserve Estimate.

Beta Hunt Nikel Operation
The nickel operation extracts mineralization hosted in two distinctly different styles of mineralization:
• In the Gamma, Beta Central and parts of Beta Southwestzones, where nickel mineralization is narrow vein and flat lying, mineralization is mostly mined with handheld airleg drills, using the room-and-pillar method.
• In the East Alpha, Beta 40, and parts of Beta Southwest zones, where nickel mineralization is narrow vein and more steeply dipping, mineralization is mined with small scale mechanised equipment, using a cut-and-fill method.

The room-and-pillar method is mined conventionally, using handheld airleg drills. These drills are also used for installation of rock bolts. Holes are charged using ANFO and the target advance is 2.0 m per round. In the flat-lying room-and-pillar stopes, broken ground is scraped using winches to ore drives at the front of the stopes or into an orepass feeding a stockpile. Here, material is excavated using narrow vein (3 t payload) LHDs and trammed to re-muck stockpiles where it is rehandled by the large LHD onto 50 t trucks.

In the steeply dipping flat back stopes, the loading drives have been sized to allow immediate loading of broken material by narrow vein LHDs, eliminating the need for scrapers. Material is also excavated using narrow vein (3 t payload) LHDs and trammed to re-muck stockpiles where it is rehandled by the large LHD onto AD60 trucks.

Mine Design
Stopes are established with an initial 3.5 m by 3.5 m cleaning/bogging ore drive along the down-dip side of the stope, extending the entire strike length. This bogging drive allows sufficient operating space for a typical narrow vein LHD to load ore which ultimately gets scraped down from the roomand-pillar broken ore sections. Some areas aimed to reduce development by establishing a crosscut below the mining horizon and developing two separate rises to access the room-and-pillar sections. One rise is used for a travelling way, while the other serves as a short ore pass, cleaning ore via electrical winch to a Stockpile. Ore is scraped from rooms and holings into this ore drive or ore pass using electrical scraper winches, allowing these stopes to be developed at a low stope width which is the greater of either a 1.9 m minimum width cut (measured on true-width) or actual thickness of mineralization (note that the actual thickness of mineralization gets up to 3.0 m for single pass extraction). MSO runs included material up to a maximum height of 4 m, thus allowing up to a further 1 m footwall ripping on a retreat basis. A significant portion of the Gamma orebody allows for the additional maximum of 1 m footwall ripping, as shown in Figure 16.5. The control afforded by use of handheld drills (at the expense of productivity) results in no additional dilution beyond the minimum stoping height. The planned stoping width is 1.7 m, with planned overbreak equating to an additional 0.2 m, resulting in a finished excavation height at a minimum of 1.9 m high. With the resource being wider in places, room-and-pillar ore drives were designed utilising a shanty profile and were evaluated in the design. As such no additional dilution was allowed for within these drives but were reported as ore or waste according to their evaluated grades.

All cut-and-fill sections allowed for 10% unplanned dilution, similar to traditional development, but the split-fire ore less than 2.3 m resource width included an additional 0.15 m dilution between the ore and waste contact. Recovery was planned as a standard 90% recovery, as some of the ore may be left behind bogging on top of previous waste filled cuts. A further 10% ore loss can be applied to the <1 m resource cut-and-fill sections, but will impact recovered tonnes only marginally, as these tonnes equate only 3% of the cut-and-fill mined ore tonnes and only 0.5% of the total ore tonnes mined in the project.

A portion of the cut-and-fill tonnes (~19.3% of cut-and-fill mined ore tonnes) has widths in excess of 6.5 m up to a maximum of 15.4 m wide. In subsequent levels of study these areas can be investigated in more detail and possibly utilise an alternative mining method. Some of these stopes may be more conducive to mine with room-and-pillar as dip flattens in some places or alternatively opportune sections or in steeper dipping sections longhole open stoping may be considered, dependent on geotechnical recommendations.

Comminution

Crushers and Mills

Summary:

HIGGINSVILLE PROCESSING FACILITY Crushing Mill feed is trucked to the ROM pad from open pits in the immediate Higginsville area together with underground ore from the Beta Hunt Mine located 73 km to the north. 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 Trio 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. In addition, there are separate surge bins that are operated in closed circuit with a 2.4 m wide by 7.3 m long Oreflow double deck vibrating screen. Crushed material exits the product screen with a P80 of 10 mm and is stored in the fine ore bin. The fine ore bin has a live capacity of 1,500 t. The crushing circuit contains one Ramsey belt scale (CV02) for measuring mass of circuit ore. Grinding Crushed mill feed is withdrawn from the fine ore bin via a belt feeder (CV05), which transfers the crushed product onto the mill feed conveyor (CV07) that feeds into the ball mill (ML01). 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. The ball mill is a LMMP/CITIC-HMC 4.90 m diameter by 6.77 m effective grinding length (“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. Slurry from the grinding and classification circuit is passed over a trash screen to ensure that no oversize particles enter the leaching circuit and to remove plastic and other containments from the slurry. The trash screen is a 1.5 m wide by 3.6 m long horizontal vibrating screen with an aperture size of 0.80 mm. Undersize from the trash screen is directed to the leach feed distributor ahead of the 1,000 m3 leach tank. LAKEWOOD GOLD PROCESSING FACILITY Crushing Mill feed is trucked to the ROM pad with underground ore from the Beta Hunt Mine located 56 km to the south. The mill feed is classified and stockpiled according to gold grade and is not typically blended. 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 is provided by a contract crushing provider who uses a variety of mobile crushing equipment, including jaw and cone crushers plus screens, to achieve a final crushed product with a P80 of 10 mm. This product is then stockpiled by a radial stacker onto the ground. The crushing circuit contains one Ramsey belt scale (CV02) for measuring mass of circuit ore. Grinding Crushed mill feed is fed by a loader via a belt feeder, which transfers the crushed product onto the mill feed conveyor (CV04) that feeds into the ball mill (ML01). The grinding circuit consists of a grate discharge ball mill, hydro-cyclone cluster classifier and gravity recovery circuit. 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. Slurry from the grinding and classification circuit is passed over a trash screen to ensure that no oversize particles enter the leaching circuit and to remove plastic and other containments from the slurry. The trash screen is 1.5 m wide by 3.6 m long horizontal vibrating screen with an aperture size of 0.80 mm. Undersize from the trash screen is directed to the leach feed distributor ahead of the 1,546 m3 leach tank.

Processing

• Gravity separation
• Consep Acacia Reactor
• Centrifugal concentrator
• Smelting
• Crush & Screen plant
• Intensive Cyanidation Reactor (ICR)
• Carbon re-activation kiln
• Flotation
• Agitated tank (VAT) leaching
• Concentrate leach
• Carbon in leach (CIL)
• Elution
• Carbon adsorption-desorption-recovery (ADR)
• Solvent Extraction & Electrowinning
• Cyanide (reagent)

Summary:

Gold mine production from Beta Hunt is processed at both the 100% owned Higginsville and Lakewood processing facilities. Nickel mine production is processed at BHP’s Kambalda Concentrator.

Gravity and Intensive Cyanidation
A gravity separation circuit is included in the design to enhance the recovery of gold that concentrates in the hydrocyclone 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 1.2 m wide by 2.4 m long horizontal vibrating screen with an aperture size of 3.25 mm. 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 at the Higginsville GPF, and a XD30 Knelson Concentrtor at the Lakewood GPF.

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 at the Higginsville GPF consists of one 1,000m3 leach tank and six CIL carbon adsorption tanks, all with a 1,000 m3 capacity. The leach and adsorption circuit consists of one 1,546 m3 leach tank and seven CIL carbon adsorption tanks, with total 2,337 m3 capacity at the Lakewood GPF.

All tanks are mechanically agitated with dual, open, down-pumping impellor systems powered by 55 kW 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 at the Higginsville GPF and 12.8 hours at the Lakewood GPF. Discharge from the leach tank at the Higginsville GPF 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. Discharge from the leach tank at the Lakewood GPF will overflow into the first of seven CIL tanks (tanks 11 to 17) which the combined adsorption residence time is 20 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 at the Higginsville GPF and tank 11 to 17 at the Lakewood GPF. Loaded carbon is pumped from adsorption tank one and 11 respectively to the gold room elution circuit periodically for stripping of the gold.

The target pH in the leach circuit is 8.6 and the target cyanide concentrations up to 300 ppm. An on-line free cyanide analyser is used to control the cyanide addition. Cyanide can be added to tank one and tank three at the Higginsville GPF and tank 11 and 13 at the Lakewood GPF. Dissolved oxygen probes are installed in tanks one and two.

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 washed to remove the gold concentrate, which is then 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 onto steel wool cathodes in the Acacia cell. The gold is recovered and smelted in a similar manner to the gold produced by the Pressure Zadra circuit. Barren carbon is reactivated using a liquefied natural gas fired horizontal kiln at around 700 degrees Celsius prior to being returned to the adsorption circuit for reuse.

Tailings Disposal Slurry from the last CIL tank flows by gravity to the feed box of the tailings screen. The tailings screen is a 1.5 m wide by 3.6 m long horizontal vibrating screen with an aperture size of 0.8 mm. The screen undersize will flow by gravity to be directed to either the tailings thickener, or allowed to bypass the thickener and report directly to the tailings pump hopper. The screen oversize (trash and carbon fines) is collected and stored in a self-draining carbon fines bin located at ground level.

Plant tailings slurry is pumped through a polyethylene pipeline to the TSF. Pressure and flow in the lines is monitored on the citect system to detect high pressures that result from line obstructions or sanding or low pressure resulting from possible pipe failures.

Nickel
Processing of Beta Hunt mineralization is performed offsite, by BHP under a tolling contract.

Nickel mineralization is processed by BHP at the Kambalda Nickel Concentrator and more recently at the Leinster Nickel Concentrator, both are flotation-style nickel concentrators.

Mineralization is blended with mill feed from other mines and the recovery credited to Beta Hunt is based on the grade of feed. Concentrate produced from Beta Hunt mineralization is treated and refined by BHP under standard commercial terms.

Water Supply

Summary:

Beta Hunt mine
Service water that is sourced from groundwater stored in what is effectively an aquifer created by the mined-out Silver Lake deposit. Storage tanks have been added to provide surge capacity.

Potable water is supplied by SIGMC and BHP.

Lakewood Gold Processing Facility
Process water is stored for use in the process water tanks. Process water is made up of bore water, tailings return water from Lakewood, and offtake from Northern Stars KCGM operation.

Potable water is sourced from the WA Water Corporation in Kalgoorlie and is trucked in. The potable water is utilised in the process plant, administration building, workshop, and stores.


Higginsville Gold Processing Facility
Process water is stored for use in a 5,000 m3 process water dam. Process water is made up of raw water from the Chalice production source and tailings return water. Incoming raw water from Chalice reports to the disused Aphrodite pit before it is pumped to the site raw water dam of 2,000 m3 capacity.

Potable water is sourced via accessing the WA Water Corporation supply line from Kalgoorlie to Norseman. Potable water is utilised in the process plant, administration building, workshop, stores, main camp, and mining offices.

Production

Operational metrics

Personnel

Job Title	Name	Phone	Email	Profile	Ref. Date
Alternate Underground Manager	Kasandra Braddon				Dec 21, 2023
Chief Operating Officer	Peter Ganza				Apr 25, 2024
Environmental Manager	Alex Ruschmann	(08)-9278-6503	alex.ruschmann@KaroraResources.com.au		Aug 1, 2023
Mine General Manager	Stasi Capsanis				Aug 1, 2023
Mining Manager	Wayne Gough				Aug 1, 2023
Processing Manager	Mark Atta-Danso				Aug 1, 2023
Project Superintendent	Philip Botha				Aug 1, 2023