Name and Location
Nova nickel project, Australia.

Client
Sirius Resources.

Project Description
A definitive feasibility study (DFS) on the Nova project has indicated the project as technically low risk and it can be highly profitable in less than two years. The outcomes of the DFS are remarkably consistent with those of the scoping study.

Nova has a maiden probable ore reserve comprising 13.1-million tonnes grading 2.1% nickel, 0.9% copper and 0.07% cobalt for a contained 273 000 t of nickel, 112 000 t of copper and 9 000 t of cobalt.

The planned mine is based on a 1.5-million-tonne-a-year underground operation with decline access. The principal stoping method will be sublevel open stoping (SLOS), with paste fill to maximise extraction. An estimated 83% of the planned production will be from sublevel open stoping, with the remaining 17% of production from the long-hole echelon retreat stoping method.

The SLOS stopes will measure up to 25 m x 25 m horizontally and 70 m in height, containing up to 200 000 t of ore per stope.

The life-of-mine-plan includes 7% dilution, of which 5% is modelled at a dilution grade of 0.2% nickel. Stope ore recovery is calculated to be 95%, with development ore recovery being 100%.

The stopes will be backfilled using paste fill, produced from low-sulphur flotation tailings recycled from process-plant waste material. Comprehensive paste-fill testwork indicates that high-strength paste backfill material can be successfully generated using Nova process tailings and shows that a suitable paste fill can be produced to meet the requirements of the mine development.

Ore and waste will be hauled in 60 t underground trucks up a straight, one-in-seven gradient decline. The decline has been designed to allow for conveyor haulage to be retrofitted at a later date if deemed appropriate.

Underground grade-control drilling will be from a hanging wall drive established early in the development sequence. This will enable all grade control drilling for the entire mine to be completed within 24 months. This hanging-wall drive will also be used for paste fill reticulation.

The processing plant will have a 1.5-million-tonne-a-year nameplate capacity and will use a conventional crushing process, with a primary crusher fed by a dedicated front-end loader from stockpiles. A mobile crusher has also been incorporated into the design as backup for the primary crusher. Grinding by an open circuit semiautogemous mill will be followed by a ball mill in closed circuit with hydrocyclones.

The flotation flowsheet required to produce separate copper and nickel concentrates is an open circuit, based on roughing, cleaning and cleaner scavenging. The circuit will be replicated for copper and nickel circuits, and regrinding on particular streams will be used to increase liberation and recovery for both circuits.

Low-sulphur tailings will be sent to either a high-density polyethylene (HDPE) plastic-lined tailings storage facility (TSF) or to the paste plant. The TSF has a designed storage capacity to store the process tailings not used as paste fill for the underground mine and will also be used as a reservoir for initial mine dewatering water. The TSF design is an above-ground impoundment with a single perimeter embankment and it will be lined with a composite liner system comprising a clay layer and an HDPE layer.

A detailed flowsheet and plant design have been completed and the site layout has been finalised. The plant layout has been designed with expansion capability, should additional mineralisation be discovered or throughput be increased. The crushing, grinding and flotation circuits have been sized to allow for a range of material types with varying comminution and flotation characteristics to minimise the risk of bottlenecking.

Groundwater exploration, pump testing and modelling simulations have been completed around the Nova-Bollinger deposits. Results indicate that some dewatering of the mine environment will be required during mine development. This water will be stored in the TSF and is expected to provide sufficient water for the first two years of mining and processing operations.

Beyond this period, process water will be sourced from three water bores identified in other aquifers within 4 km of the planned mine. As a contingency, further groundwater resources exist within a 50 km radius of the project and are available for development.

A reverse osmosis plant will provide desalinated water for concentrate cleaning and drinking water.

The project has a ten-year mine life, subsequent to development.

Net Present Value/Internal Rate of Return
Not stated.

Value
The project has an estimated capital cost of A$473-million, including a A$22-million contingency.

Duration
Construction at the site is expected to start in early 2015, with first nickel and copper concentrate expected in the first quarter of 2017.

Latest Developments
Sirius has announced that the development of the Nova project is running on schedule, with the company also announcing GR Engineering Services as the preferred tenderer for the processing plant.

Based on the proposed schedule, engineering and detailed design of the plants are expected to start in the second quarter of this year, with construction scheduled to start in the fourth quarter.

Contracts for the power station, overhead power distribution and bulk earthworks have yet to be awarded.

Meanwhile, the mine is progressing on, or ahead of schedule, in all areas, with underground mining equipment already on site to start the development of the decline within the coming weeks.

Construction of the tailings dam has also started, while the run-of-mine pad has largely been completed.

The construction camp has been completed, and the 500-person village is now under construction and on track for completion in May.

Site infrastructure corridors are at an advanced stage of construction and the airstrip has been cleared and is being levelled to create the base for a 2 km sealed all-weather landing strip.

Key Contracts and Suppliers
None stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Sirius Resources, tel +61 8 6214 4200, fax +61 8 6241 4299 or email admin@siriusresources.com.au.