Thunderbird is the first significant mineral sand deposit to be discovered in the Phanerozoic Canning Basin, and is one of the largest and highest grade mineral sands deposits globally, including those currently in production. The Thunderbird deposit formed during an Early Cretaceous marine regression and is hosted by highly weathered Broome Sandstone.

Mineralisation occurs as a thick, broad sheet like body striking northwest, extending from surface to a maximum known depth of 155m over an area at least 11km by 7km. These extents have not been closed off with mineralisation remaining open to the north, south and west. The average depth to top of the main body of mineralisation is 24m and the average mineralised thickness 45m. The deposit is flatlying along the north-eastern flank, but with a dip steepening to 4°along the south-western flank.

Enclosed within the Thunderbird formation is a continuous, very-high grade heavy minerals (>7.5%) zone named the “GT Zone”. This zone is up to 43m thick (average 15m) over an area at least 9km by 7km, strikes approximately north-south, follows the dip of the Thunderbird formation and is open along strike to the south and north.

Based on the results of the fieldwork studies undertaken to assess excavatability (Sonic core, Bauer drilling and costeans) bulk mining techniques have been chosen for ore mining at the Thunderbird project, incorporating dozer traps and in-pit feed preparation units. Topsoil and overburden will be excavated and transported using truck and excavator. Oversize material rejected from in-pit feed operations will be rehandled by Wheeled Loader to locations within the active mine void. Following excavation and classification, ore will be slurried and pumped to a nearby wet concentration plant. Retaining cells will be constructed in the developed mine void from waste material for the return of process tails for consolidation into backfill. Following consolidation, topsoil will be returned in a continuous rehabilitation process. The mining techniques and equipment proposed are conventional and well tested dry mining techniques employed in existing similar mineral sands operations worldwide.

The processing flowsheet uses the application of proven metallurgical processes and standard mineral sand separation techniques (spirals, magnetic and electrostatic separators) to enable production of ceramic grade zircon (Premium Zircon) and high quality ilmenite (LTR Ilmenite) along with valuable coproducts of leucoxene (Hi-Ti88), zircon concentrate and Titano-magnetite.

The HiTi88 recovery circuit has been removed from the process design with the previously separated HiTi88 product, now reporting to the zircon concentrate.

The treatment of the zircon-rich (non-magnetic stream) with a mild Hot Acid Leach (HAL) followed by an attritioning process is sufficient to enhance the effectiveness of the primary high tension separation circuit, and remove iron coatings on the zircon grains producing a Premium Zircon product.

The treatment of the Primary ilmenite (conductor magnetic stream) concentrate with a reductant roast gas (Low Temperature Roast (LTR)) changes the oxidation state of contaminant ferric iron oxides in the concentrate, enabling subsequent clean separation of these iron-rich minerals from the ilmenite with conventional magnetic separation equipment. This step produces a high-grade, low impurity, LTR Ilmenite product. This LTR Ilmenite product demonstrates high solubility, reactivity and FeO:Fe2O3 ratio to match the best sulphate ilmenite available globally.

The LTR process effectively acts as a homogenisation step, producing a consistent product across a range of feed grades, and can accommodate variable levels of iron oxide in the feed. Furthermore, adjustment of operating parameters (syngas makeup, temperature and residence time) enables control of final product characteristics.