The Batman and Quigleys gold deposits of the Mt Todd Mine are formed by hydrothermal activity, concomitant with retrograde contact metamorphism and associated deformation, during cooling and crystallization of the Tennysons Leucogranite and early in D2.

The deposits are similar to other gold deposits of the porphyry copper gold (PCG) and are classified as orogenic gold deposits in the subdivision of thermal aureole gold style. The Batman deposit shares some characteristics with intrusion-related gold systems, especially in terms of the association of gold with bismuth and reduced ore mineralogies. This makes the deposit unique in the PCG.

The geology of the Batman deposit consists of a sequence of hornfelsed interbedded greywackes, and shales with minor thin beds of felsic tuff. Bedding is striking consistently at 325°, dipping at 40° to 60° to the southwest. Minor lamprophyre dykes trending north-south pinch and swell, cross cutting the bedding.

Northerly trending quartz sulfide veins and joints striking at 0° to 20°, dipping to the east at 60° are the major location for mineralization in the Batman deposit. The veins are 1 millimeter (mm) to 100 mm in thickness with an average thickness of around 8 mm to 10 mm. The veins consist of dominantly quartz with sulfides on the margins. The veining occurs in sheets with up to 20 veins per horizontal m. These sheet veins are the main source of mineralization in the Batman deposit.

A variety of mineralization styles occur within the Mt Todd area. Of greatest known economic significance are auriferous quartz-sulfide vein systems. These vein systems include the Batman, Jones, Golf, Quigleys and Horseshoe prospects, which occur within a north-northeast trending corridor, and are hosted by the Burrell Creek Formation. Tin occurs in a north-northwest trending corridor. The tin mineralization comprises cassiterite, quartz, tourmaline, kaolin, and hematite bearing assemblages, which occur as bedding to parallel breccia zones and pipes. Polymetallic Au, W, Mo, and Cu mineralization occurs in quartz-greisen veins within the Yinberrie Leucogranite; a late stage highly fractionated phase of the Cullen Batholith. The Batman Deposit extends approximately 2,200 m along strike, 400 m across dip and drill tested to a depth of 800 m. Drilling indicates the Batman mineralization to be open along-strike and down-dip.

The mineralization within the Batman deposit is directly related to the intensity of the north- south trending quartz sulfide veining. The lithological units impact on the orientation and intensity of mineralization.

Sulfide minerals associated with the gold mineralization are pyrite, pyrrhotite and lesser amounts of chalcopyrite, bismuthinite and arsenopyrite. Galena and sphalerite are also present, but appear to be postgold mineralization, and are related to calcite veining in the bedding plains and the east-west trending faults and joints.

Two main styles of mineralization have been identified in the Batman deposit. These are the north-south trending vein mineralization and bedding parallel mineralization.

The Quigleys deposit mineralization has a distinctive high-grade shallow dipping 30°-35° northwest shear zone extending for nearly 1 km in strike and 230 m vertical depth within a zone ofmore erratic lower grade mineralization.

The Project is designed to be a conventional, owner-operated, large open-pit mining operation that will use large-scale mining equipment in a drill/blast/load/haul operation

The truck and shovel method provides reasonable cost benefits and selectivity for this type of deposit. Only open-pit mining methods are considered for mining at Mt Todd.

Open pit ore totals 208 Mt grading 0.84 g/t and contains 5.6 Moz of gold. Open pit production will have a 2.5:1 strip ratio over the 13-year LoM. Upon completion of conventional mining, the existing heap leach pad will be processed.

Crushing Modeling
The run of mine ore from the pit is expect to have a maximum particle size of 1000 mm and F80 to the primary crusher of 400 mm. Two stages of crushing, primary and secondary are required to reduce particle size to a P80 of 31.5 mm, required as feed to the HPGR tertiary crushers. A single gyratory crusher is sized for the primary duty reducing ore size to a nominal P80 of 130 mm. Two secondary cone crushers operating in parallel and in closed circuit with two sizing screens cutting at 40 mm, are used to produce the feed to the HPGRs at product size P80 of 31.5 mm.

Primary Crusher
The primary crusher power was calculated using both the FLSmidth gyratory calculation model and the Metso Bruno model. Using the CWi of 20 kWh/t and a fall through percentage of zero to simulate peak conditions, both models provided peak primary crushing power requirements of a nominal 574 kW and 576 kW respectively to reduce a feed F80 of 400 mm to a product P80 of 130 mm.

Secondary Crushers
Secondary crushing with closed circuit screening was modelled by FLSmidth. Two Raptor 1300 cone crushers operating in parallel are used to reduce the primary crusher product to a final product P80 of 31.5 mm, for the 50,000 tpd Base Case.

HPGR
HPGR power requirements to reduce the HPGR feed to a final product P80 of 3.25 mm was shown by the Polysius testwork to be 1.9 kWh per tonne of feed to the HPGR. The feed to the HPGR is the sum of new feed plus the recirculating load screen oversize material, less Ore Sorting reject. The total feed to the HPGR is two times the fresh feed rate. HPGR testwork supported vendor recommendations for two HPGR Polycom PM8-24/17, each equipped with 2 x 2,650 kW drives.

Grinding and Classification
Two Ball mills will be used. The parallel Ball Mill circuits are in a conventional configuration. Fresh feed from the fines screens underflow will gravitate to the mill discharge hopper and will be pumped together with the mill discharge slurry to the Cyclones. The cyclone underflow will gravitate to the ball mill feed. The overflow will gravitate to the Secondary Grind feed sump. The secondary grinding cyclone overflow will be pumped to the pre-leach thickener and the underflow will be sent to the VXP mills for secondary grinding. An automated ball charging system will be provided to deliver approximately 15 tonnes of balls per day to each mill.

The flowsheet consists of primary crushing, closed circuit secondary crushing, closed circuit tertiary crushing using high pressure grinding rolls (HPGRs), ore sorting, two-stage grinding, cyclone classification, pre-leach thickening, leach and adsorption, elution electrowinning and smelting, carbon regeneration, tailings detoxification and disposal to conventional tailings storage facility (TSF).

Process recovery was determined based on ore types. Three ore types, sulfide, mixed, and oxide were identified for the open pit and will have recoveries of 92.9%, 91.8%, and 91.5%, respectively. The heap leach pad will have a recovery of 90.7%. An additional 1% for net solution loss is applied to all the deposits and heap leach which results in a LoM average recovery of 91.9%.

Based on thickener sizing parameters received from RDI Minerals, that were based on additional 2019 rheology and settling test work undertaken by Pocock Industrial for a final grind size of 40um, ........