Name and Location
Thunderbird mineral sands project, Australia.

Client
Sheffield Resources.

Project Description
A prefeasibility study (PFS) update on the project has shown significant improvements to the previous PFS study completed in May 2015, which has enhanced Thunderbird’s economics and technical feasibility.

The update is based on a mineral resource of 3.2-billion tonnes, grading 6.9% heavy minerals for 18.5-million tonnes of zircon, 61.8-million tonnes of ilmenite, 6.9-million tonnes of leucoxene and 5.9-million tonnes of HiTi leucoxene.

The project’s current mineral resource supports an initial 40-year mine life, with significant scope to increase this in the future. After ramp-up to an 18-million-tonne-a-year throughput, Thunderbird will be one of the world’s largest dry mining mineral sands operations.

Mining will be conducted using the strip mining and backfill method typically used in dry mining operations in the mineral sands industry. Mining will start with the excavation of an initial pit to expose the ore. As the pit advances, waste overburden and tails will be used to provide a dam wall within the mine void, which will be backfilled with tailings, contoured and rehabilitated.

At the proposed 12-million-tonne-a-year run-of-mine (RoM) feed rate of 1 620t/h, four large dozers will deliver the ore to two 810 t/h skid-mounted dozer trap mining unit plants (MUPs). A third MUP will be on standby to minimise downtime during mine face relocation and maintain consistent throughput. In year eight, throughput will increase to an 18-million-tonne-a-year RoM feed rate of 2 430 t/h by deploying an additional MUP and supporting mobile equipment.

Ore mining will be supported by a fleet of loaders and 100 t trucks. Waste mining, oversize removal and dam wall construction and rehandling will be undertaken using a fleet of loaders, trucks, excavators and scrapers. Low strip ratios in the early years will enable the ore mining fleet to service the waste mining load. The MUPs will screen coarse oversize, with undersize fed to a scrubber trommel. The undersize from the trommel is slurried and pumped to the wet concentrator plant.

The Thunderbird mineralisation will be processed through a conventional heavy mineral sands processing circuit to deliver a suite of zircon, ilmenite, and HiTi88 products. The process includes an ilmenite upgrade using a low-temperature roast (LTR) to upgrade the primary ilmenite by 22% to produce a high-grade (56.1%) sulphate ilmenite.

Overall recovery of ilmenite to product (45% to 47% titanium dioxide) is 74% and overall recovery of LTR ilmenite (56.1% titanium dioxide) is 68%.

Overall zircon recovery, excluding semiprocessed and recirculated streams, has been calculated at 67%. The primary (66.6 zirconium dioxide) zircon is about 80% of the recovered zircon. A secondary (65.1% % zirconium dioxide) and special (62.8% zirconium dioxide) zircon were also produced.

HiTi88 (87.7% titanium dioxide) product recovery, excluding semiprocessed or recirculation streams, is 40%.

Net Present Value/Internal Rate of Return
The project has an estimated payback period of 3.4 years.

Value
The capital cost of the project in the PFS was estimated at $394.1-million; in the update, preproduction capital has been reduced by 26% to A$271-million.

The preproduction capital total includes A$27.7-million for an ilmenite upgrade plant, which will enable Sheffield to produce large quantities of consistently high-quality, high-grade sulphate ilmenite over the 40-year mine life.

Duration
Commissioning of the project is expected in 2018, coinciding with an expected global supply gap.

Latest Developments
Sheffield has reported a maiden ore reserve of 683-million, grading 11.3% heavy minerals, for its Thunderbird project.

“Releasing a maiden ore reserve is the final step in closing out the Thunderbird PFS and moving to a bankable feasibility study (BFS) . . .” Sheffield MD Bruce McFadzean has said.

The PFS was based on a conventional dozer trap mineral sands mining operation, involving an initial 12-million-tonne-a-year throughput, increasing to 18-million tonnes a year to produce an average of 100 000 t/y of zircon and 382 000 t/y of high-grade sulphate ilmenite over the 40-year mine life.

Meanwhile, Sheffield has finalised the scope of the BFS, and a tier-one study manager will be announced within the next month.

Sheffield is also continuing with native title negotiations and work towards securing environmental approvals for the Thunderbird project. Marketing and financing options will also be pursued in parallel with the BFS and approvals process.

Key Contracts and Suppliers
None stated.

On Budget and on Time?
Not stated.

Contact Details for Project Information
Sheffield Resources, tel +61 8 6424 8440, fax +61 8 9321 1710 or email info@sheffieldresources.com.au.