The Sulphur Springs Copper-Zinc deposit is hosted by the Kangaroo Caves Formation, a volcano-sedimentary sequence within the north-north easterly trending tectonostratigraphic domain known as the Lalla Rookh–Western Shaw Corridor (LWSC) in the central east of the Archaean Pilbara Craton. The deposit is a well-preserved example of an Archaean volcanogenic massive sulphide (VMS) style deposit in a low-grade metamorphic terrain.

Mining of the Sulphur Springs deposit has been assumed to be by a combination of open pit and underground methods. The open pit mine life is currently projected to be approximately four years immediately followed by the underground for a further six years. The selected mining method, design and extraction sequence are tailored to suit orebody characteristics, minimise dilution and ore loss, utilise planned processing plant capacity and expedite free cash generation in a safe manner. Mining schedules have been based on realistic mining productivities with readily achievable mining rates along with consistent material movements.

Open pit mining dilution and recovery modifying factors were simulated by modelling to a Selective Mining Unit (“SMU”) of 5mX x 5mY x 2.5mZ. The re- blocking technique dilutes fully into the SMU size and the resultant model is then used as a diluted model.

Key parameters used as part of the pit optimisation process included (but are not limited to):
- Assumed average of 1.25Mtpa of ore processing
- Mining costs derived from submissions received from mining contractors who offered pricings for the previous study
- Metallurgical recoveries provided by Lycopodium (who completed test work in conjunction with ALS) - Processing and infrastructure costs provided by Lycopodium (based on an updated and optimised plant design and infrastructure requirements).

The intention is to mine the Sulphur Springs deposit using hydraulic excavators (backhoe configuration) and rear dump trucks after the material has been drilled and blasted. For the first two and half years of open pit operations, the fleet will consist of 1 x Liebherr 9200 (210 t-class) plus 1 x Komatsu PC1250 (120 t-class) excavator. These will be supported by a fleet of Komatsu HD785-7 dump trucks.

During this period, overburden will be removed and the orebody exposed. After establishing the working area, the Liebherr 9200 excavator is de- mobilised and for the remainder of the open pit life mining is carried out by the Komatsu PC1250 excavator. All mining activities will be conducted by a specialist mining contractor.

Underground mining will be completed through Modified Sub-Level Caving (“M-SLC”) techniques. Geotechnical parameters remained the same for underground mining from previous studies as no further work has been completed on the underground portion of the ore body.

The proposed mining method requires a pattern of generally evenly spaced and sized rib pillars separating the primary (core) stopes, which are connected via an overlying sill pillar.

The sill pillar separates the active mining area from the overlying mined out area, which contains waste rock fill introduced from a pass breaking through to a designated area in the floor of the pit.

The mine is developed by a decline system with a mine portal established on the footwall side of the orebody in the open pit at the 1,200mRL. This will allow central access to the ore from the initial single heading decline, which will then allow development of a single main decline system located to the east of the Main fault. This decline will allow access to both the East and West lodes.

Detailed mine sequencing shows that a minimum mine production rate of 1.25Mtpa is suitable from a mining inventory (inclusive of Inferred classification material) of 5.6Mt grading 3.7% Zn and 1.4% Cu, an increase from the inventory presented in the VES of 4.9Mt grading 3.7% Zn and 1.3% Cu.

Underground mining will be undertaken by rubber tyred, diesel-powered equipment utilising 55-tonne haul trucks and 2900 scale boggers.

Total mining operations for the underground, including initial mine development and subsequent ore mining, will take place over a period of approximately 6.5 years.

After reviewing a number of mining methods, M-SLC is still the preferred extraction method with some areas being extracted via Long Hole Open Stoping.

The Kangaroo Caves project has been reviewed as a high-level study considering a single simplified mining method of top-down longitudinal open stoping with rock pillars. Benchmark operating costs and mining assumptions have been applied.

The underground operation has been assumed to be accessed from a portal location at surface (1,200mRL). Due to the flat-dipping nature of the ore body, longitudinal ore drives on 10m level intervals with two levels being mined off one level access have been selected, resulting in level accesses off the decline designed on 20m level intervals.

The ore mining schedule supplements the Sulphur Springs feed, adding a further 1.8 Mt of inventory grading 3.8% Zn and 0.7% Cu.

Ore production is at a rate of 1.25Mtpa for both the open pit and underground operations.

The Sulphur Springs process plant consists of a mineral processing flotation concentrator with associated services and ancillaries. The plant has been designed to take run-of-mine (ROM) ore from the mine and concentrate the Copper and Zinc bearing minerals to produce a Copper-bearing product, a Zinc-bearing product and a barren tail.

The process facilities involved include the following:
- Crushing
- SAG and Ball milling
- Flotation
- Thickening
- Filtration
- Product handling
- Tailings disposal
- Reagents
- Services and Ancillaries.

The plant has been designed in accordance with accepted industry practice and the flowsheet has been constructed from unit operations that are well proven in industry and based on the results of current and historical test work programs.

Crushing and Coarse Ore Storage
Run-of-Mine (ROM) ore will be reclaimed from the ROM pad by a front-end loader and fed to the ROM bin with a live capacity of approximately 45m3. The ROM bin will be fitted with a static grizzly to allow diversion of large rocks for subsequent breakage by mobile rock breaker.

Ore will be drawn from the ROM bin at a controlled rate to the vibrating grizzly via a variable speed apron feeder and will feed into a single toggle jaw crusher designed to process 1.25Mtpa of fresh ore (1.29Mtpa of Transitional ore).

The grinding circuit will consist of a Semi Autogenous Grinding (SAG) mill in open circuit followed by a ball mill in closed circuit with hydro-cyclones.

Primary crushed ore from the surge bin will be withdrawn by a single apron feeder. Variable speed control of the mill will provide processing flexibility to cater for liner wear and variations in ore grindability.

The original design basis for the Sulphur Springs process plant was based on treating fresh ore. Test work conducted on Transitional samples determined that a single product float (Copper or Zinc) is required in order to maximise the recovery and grade of the target product.

The flotation feed distribution box ahead of the flotation circuits allows the hydro-cyclone overflow to be directed to either the Copper or Zinc flotation circuits as required.

The flotation circuit will consist of sequential flotation of Copper and then Zinc sulphides.

In the first stage of flotation, chalcopyrite particles (Copper-bearing minerals) will be selectively separated from the sphalerite, pyrite and gangue minerals. In the next stage, sphalerite (Zinc-bearing minerals) will be selectively separated from the pyrite and gangue minerals. The Copper concentrate from the first stage of flotation and the Zinc concentrate from the second stage of flotation will then be separately thickened, filtered and stored prior to transport to customers.