The Paulsens deposit lies within the west northwest trending regional Wyloo anticlinal dome. Archaean Fortescue Group metasediments and metavolcanics of the Hamersley Basin are exposed in the core of the dome and form the host rocks of the Paulsens deposit. Paulsens is a mesothermal, orogenic lodestyle gold deposit with mineralisation occurring within a structurally controlled, 40m thick, quartz vein, hosted by a folded, sedimentary sequence. The quartz body is found between the two halves of a large faulted Gabbro dyke. This Gabbro dyke’s orientation is somewhat oblique to the regional foliation so the apex of the folded quartz slowly moves out of this corridor.

The main body of mineralisation comprises an Upper (UZ) and Lower (LZ) Zone located on the hanging wall and footwall contacts respectively. Drilling has defined a down plunge extent in excess of 1,000m to around 550m below surface. The mineralisation is cut in places by a series of steeply dipping dolerite dykes that vary from one to ten metres in thickness.

The Paulsens underground is accessed via a single decline at the bottom of a 21m deep boxcut developed into the side of the Paulsens Hill which occurs adjacent to the mine office and milling complex. Underground mining takes place from a single decline with level accesses than run south to north with ore drives orientated east to west of the level accesses .

Currently, Paulsens produces around 0.47mtpa. The primary stoping method at Paulsens is up hole longhole open stoping, with stopes retreating in a top down sequence and towards a central access. Other mechanised ore extraction methods include jumbo stripping and benching. There is also a limited amount of airleg stoping in the Paulsens Upper Zone. Stope sizes vary from ~1,000t to ~7,500t. The centroid of mining is approximately 750m vertically below the surface.

The Paulsens Gold Mine utilises a Carbon in Leach (CIL) circuit for the extraction of gold.

The crushing plant is a three-stage facility that treats up to 150 tph of minus 550mm Run of-Mine (ROM) ore, to produce a crushed product with P80 of 8mm. The crushing plant consists of a primary jaw crusher and secondary and tertiary cone crushers. Oversize from an inclined double deck vibration screen (apertures 20mm and 8mm) reports to the cone crusher, and undersize reports to the fine ore storage bin (FOB), or the on-ground fine ore stockpile (FOS).

The grinding and classification facility operates 24 hours a day, 365 days a year, to mill 450 000 tpa. Grinding is performed by a 3.51m diameter by 5.63m long (inside shell) rubber lined overflow ball mill, equipped with a 1,000KW motor. A cluster of six hydrocyclones (four operational, two standby) is used to classify the slurry to a P80 of 106µm.

The underflow from the hydrocyclones is split with a stream passing over a gravity screen to scalp the plus 2.4mm material before it reports to two Knelson Centrifugal Concentrators that are installed in parallel. The Knelson Concentrators collect free gold particles and particles with high density by applying a centrifugal force. Concentrate periodically passes to a pair of Acacia Reactors for gold recovery. The Acacia Reactors utilise sodium hydroxide, cyanide, and Leach Aid to leach the gold particles. Gold is recovered from the leach solution via dedicated gravity electrowinning circuits inside the gold room.

Overflow from the cyclones gravitates to a 7.0m diameter high rate thickener fitted with an auto- dilution feed well. Diluted flocculent is added to the feed well through sparges. Thickener overflow flows by gravity back to the process water tank for reuse in the grinding circuit. Thickener underflow, at 55% solids w/w, gravitates into the leach feed pump hopper and is pumped to a conditioning tank where the slurry is pre- oxygenated utilising a Multimix system. The conditioned slurry then gravitates to the first of six 150m3 CIL tanks operating in series to give a total residence time of 25 hours. Each tank has dual open impellor agitators and an intertank screen.

The elution and gold recovery circuit operates seven days per week/24 hours per day, treating 2.0 tonne batches of carbon, with up to seven strip cycles per week. Carbon, loaded to 4,000 gpt gold, is recovered from CIL tanks, screened and washed to remove the slurry, and directed into the cyanide wash column. The elution circuit comprises of two columns. In the first column a cold cyanide solution wash is carried out to remove copper adsorbed onto the carbon, followed by a hot acid wash to remove nickel and other deleterious elements. The carbon is then transferred pneumatically to the second column, where elutriation takes place. The first column is constructed of mild steel and is butyl rubber lined. The second column is constructed from 304 stainless steel. The total strip cycle will take nine hours, using 36m3 of water, whilst the elution cycle uses 16.7m3 of water and takes four hours.

Pregnant solution is discharged from the elution column, via the eluate filters and recovery heat exchanger, to the electrolyte tank. The solution is pumped from this tank via the electrolyte pump to two 600mm by 600mm, electrowinning cells operating in parallel. Cell discharge gravitates back to the electrolyte tank. Electrical current is supplied to the electrowinning cells by two dedicated rectifiers (6V, 1000 A). The mild steel wool cathodes containing the electro-won gold are removed from the electrowinning cells, placed on trays and calcined at 700ºC. The sludge in the cells is removed via the drains in the bottom of the cells, and collected in buckets. Flocculant is added and excess solution is decanted prior to calcining. The calcine is mixed with fluxes, and smelted in the gas fired tilting bullion furnace with A100 crucible capacity. The bullion is stored in the gold room safe.