Plutonic Gold Operations is located within the Archaean Plutonic-Marymia Greenstone Belt, an elongate, northeast trending belt within the Marymia Inlier. The Marymia Inlier is an Archaean basement remnant within the Proterozoic Capricorn Orogen comprising two mineralised greenstone belts (Plutonic Well and Baumgarten), with surrounding granite and gneissic complexes. The Capricorn Orogen is situated between the Pilbara and Yilgarn Cratons and is possibly the result of oblique collision of the two Archaean cratons in the early Proterozoic.

The northeast trending Plutonic-Marymia Greenstone Belt extends over an 80 km strike length and is up to 10 km in width. The Belt is sub-divided into two volcano-sedimentary sequences, consisting of mafic and ultramafic units which are overlain by predominately felsic volcaniclastic and sedimentary rocks. These units have been subject to greenschist and amphibolite facies metamorphism, deformed by polyphase folding, shearing and faulting, and intruded by felsic porphyry and granitoid bodies. This has resulted in a strong northeast trending fabric parallel to multiple low-angle thrust faults. These thrust faultsoccur throughout the belt and are intimately associated with the known gold mineralisation.

Plutonic operation includes Plutonic underground and Hermes open pit mining objects.

Open cut mining operations commenced at the Plutonic Main Pit in 1990 and continued through to 1997. A string of satellite pits throughout the belt including Salmon pit continued surface production through to mid- 2005. In 1995, underground mining in the Plutonic Main Mine commenced from the west portal. Plutonic mine is accessed from 3 portals (west and vent located in the Main Pit) and the 550 box-hole cut portal. Underground mining takes place from 4 major declines with a series of internal ramps to access mining zones. Mineralisation zones extend over an area roughly 3.5km north to south and 2km east to west with a vertical extent of over 1350m.

Currently, Plutonic produces around 0.85mtpa from mechanised mining methods with other mining techniques also used. Longhole stoping is the main mining method used with a number of stoping techniques utilised to address the variations in orientation and shape of the stopes.

The Hermes Complex commenced being mined in December 2017 as a conventional open pit excavator-truck mining operation. A mining contractor was engaged for drilling, blasting, loading, hauling, and dumping, as well as civil services for general site maintenance works. The material mined from each pit is being stockpiled adjacent to each pit exit before being loaded onto road trains for transport along the haul road to Plutonic for processing through the existing mineral processing configuration.

Some near surface weathered material may be free-dig, but 100% of transitional material and fresh rock will be blasted. Blast-hole drilling will be undertaken using surface top hammer drill-rigs on 5 m benches using Plutonic Gold Mine Superior Gold Inc 94 hole sizes up to 115 mm diameter. Drill burden, spacing and sub-drill design will be a function of material types and powder factor. Drill and blast of 10 m benches in the upper waste sections of each pit will be reviewed. Explosive selection will depend on the presence of groundwater and the success of dewatering. The water table at Hermes is estimated at a nominal 29 m below the pit crest. For pit optimisation, ammonium nitrate fuel oil (ANFO) was assumed in the oxide material and emulsion for the remainder of the deposit.

Haul trucks with a load capacity of 100 t will be used in conjunction with 120 t class hydraulic excavators in a backhoe configuration to achieve the required waste extraction ratio and selectively mine the ore. In general, 5 m benches will be mined on two 2.5 to 3.5 m fitches (allowing for heave after blasting). In harder material, where extensive heaving of blasts is likely to occur, it may be necessary to mine the heave separately down to bench level, followed by two 2.5 m fitches to minimise ore dilution. Ancillary services to support the production fleet include graders and water trucks for haul road maintenance and dozers for maintenance of pit benches, preparation of blasted benches, along with waste dump management.

The Plutonic processing circuit is a conventional CIL plant with a hard rock processing capacity of approximately 2.0 million tonnes per year. Processing on the current rate at 850,000tpa of underground ore the processing plant has the ability to substantially increase production to full capacity (2mtpa) at a moment’s notice should the need arise.

The grinding circuit is preceded by a double toggle Jaques 60x48 (185KW) crusher at 420tph crushing capacity. The jaw crusher discharge feeds the secondary and tertiary cone crushers and double deck screening sections. The crushed minus 10mm screened product reports to a 4500 tonne enclosed fine ore bin. This product is then reclaimed by variable speed conveyors to the grinding section.

The grinding circuit comprises a Svenson 4.5m diameter by 5.63m long primary mill and two Svenson 4.2m diameter by 5.63m long secondary ball mills. The primary mill has a grate discharge and is rubber lined. Its speed is fixed at 14.6 rev/min (72% of critical) and the installed power is 1600KW. The secondary mills are rubber- lined overflow mills also with 1600KW power. The grinding circuit throughput is currently operated at 165tph with a primary mill and one ball mill configuration; this however can be increased to 230tph by running the stand-by ball mill.

Pre-leach classification is achieved using a hydro-cyclone classifier circuit consisting of 16 cyclones that are fed from a distributor. Only 6 to 8 of the cyclones are operated at any one time depending on volume of slurry in the milling circuit. The cyclones are operated at a feed pressure of 110-130kpa.

The cyclone overflow reports to the leaching and adsorption circuit where the recoverable gold is extracted by cyanidation. The circuit comprises a Carbon in Leach (CIL) circuit with two leach tanks and six adsorption tanks. Two oxygen plants supply 8-10 tonne of oxygen per day to inject into the slurry via the agitators down shaft injection. The slurry residence time in the leach and adsorption circuit is approximately 36 hours and each tank has a volumetric capacity of 1,000m3.

Loaded carbon is pumped from adsorption tank 1 in daily batches. Gold is then recovered from the carbon using a process called elution. The Plutonic elution circuit is based on the Split Anglo-American Research Laboratories (AARL) elution process in which the gold laden carbon is first acid washed, and then eluted in a stainless steel elution column using hot (120ºC) caustic cyanide solution.

The gold bearing eluate produced from the desorption process (pregnant solution) is then circulated through electrowinning cells for approximately 12 hours. During this stage gold is electrowon onto cathodes of steel wool. The barren solution remaining at the end of the electrowinning cycle is then returned to the second leach tank to fully utilise the excess cyanide associated with the solution.

The gold laden steel wool is removed from the electrowinning cells, oxidised in a calcining oven and smelted directly with fluxes in a gas- fired furnace. The smelt produces a vitreous slag containing all the base metals and impurities and gold doré bars that contain approximately 90% gold and 10% silver.

The electrowinning, calcination and smelting processes are all performed inside a high security gold room.