The deposit type is rare in this part of Queensland. It is a flat lying residual oxide deposit of a weathered gabbro intrusion that has had modifications from surface water flow and soil creep. The host rock comprises a combination of weathered material and alluvium. Ilmenite mineralisation occurs as liberated fine grains often concentrated by surface water into more slimes-rich material but the concentration may in part be related to an underlying primary concentration in the gabbro. The gabbro appears to have a primary mineralogical zonation associated with the arcuate margin of the intrusion. The ilmenite has been widely distributed throughout the mining lease with no obvious specific lateral concentrations.

The mineralisation is associated with the Goondicum Gabbro which Groen (1993) had mapped from the crater rim to the centre as comprising a ‘poikilitic marginal zone’ (hornblende gabbro), ‘lower zone laminated gabbro’, and ‘macrorhythmic zone’.

The relatively complex weathering history of the gabbro has produced two main host types for ilmenite mineralisation. The 'clay/sand' unit or ‘CS’ is believed to be an eluvial/colluvial deposit i.e. some in-situ material and some transported material possibly due to both gravity slip and alluvial processes. The second type is 'decomposed gabbro' or ‘DG’, implying a less weathered eluvial or in-situ deposit. A subset of the clay/sand unit is the 'colluvium' unit or ‘CL’, and this may have had a more water transported-related origin. The CS occurs at or near surface and includes the uppermost 20-30cm of the soil profile, designated in the drillhole logging as 'soil horizon' or ‘SL’. The CS can range in thickness, up to several metres, especially where the CL unit is associated. The CL is an important sub-set of the clay/sand mineralisation, having high slimes content, and may have formed from localised damming of alluvial channels resulting in localised flooding where the clay material in suspension settled out in depressions.

Ilmenite deposits also occur along modern stream channels as terrace remnants, which the reactivated stream has partly eroded. Less frequently, palaeo-stream channels are encountered which are filled with gravity flow colluvium with variable ilmenite grades.

The mineralisation is essentially flat lying with an undulating base. For the ML its dimensions are 3,000 x 1,500 metres with an approximate viable range in thickness of 2–10metres (low grade mineralised DG can add to a maximum thickness of 25metres). For the MLA the mineralisation dimensions are 4,000 x 2,000metres with an approximate viable range in thickness of 2–10metres (low grade mineralised DG can lead to a maximum thickness of 25metres).

The fundamental geological control to the mineralisation is the underlying spatial distribution of the gabbro and its ilmenite content, followed by the topography at the time of the different weathering/erosion phases. Ilmenite grades are not entirely related to specific weathered rock types although there is a marked segregation between the high slimes units, CL and CS_H, having higher grades than the low slimes CS_L and DG host units. The ilmenite grades of the DG unit are more directly related to the original grade within the gabbro.

The land is cleared of vegetation (trees and grass) using a bulldozer to prepare the area for mining. Approximately 20cm of topsoil is removed and stockpiled for later rehabilitation. A dry open pit mining method is proposed for ore mining using a combination of scrapers, and an excavator and truck model. The mineralisation is relatively easy digging for an excavator. Normal mining practice will be for the excavator to sit on top of the mineralisation being mined and load trucks in the pit below the excavator. This reduces the cycle time of the excavator to maximise excavation efficiency. Four 40 tonne 6WD trucks will be used to haul the mineralisation from the excavator to the ore stockpile at the feed preparation plant (FPP). The average haul distance for the ML will be 300metres and the maximum haul distance will be 2,000metres. The mining operation will also utilise scrapers on short haul, low vertical lift cycles to remove the mineralisation and deliver it to the FPP. The scrapers are more suitable for mining the thinner material which is outside the gullies. Two scrapers will be used mostly for mining in the shallow areas, while the excavator and trucks will concentrate in the gullies.

The feed to the plant comprises mineralised sand grains including ilmenite, magnetite, apatite and feldspar as both discreet and composite particles held within a barren clay matrix. Characterisation work done as part of project development showed that the valuable heavy minerals present in the feed can be recovered from the -1mm +53micron size fraction using conventional heavy mineral sands processing equipment. Once the minerals are liberated the separation processes at the wet concentrator plant are able to reject gangue minerals while recovering ilmenite and apatite product streams by exploiting the differences in their physical properties. The differing behaviour of the geological domains (CL, CSH, CSL, DG) through the process flowsheet means that the ROM material needs to be stockpiled ahead of the plant and blended before being loaded into a feed receival unit with a frontend loader. The first processing stage comprises screening, deagglomeration and water recovery in the feed preparation area.

The second stage of processing at the WCP employs a series of gravity (spirals) and magnetic (LIMS, WHIMS) circuits to separate the valuable heavy minerals and reject the gangue minerals producing final products of ilmenite and apatite. The gangue minerals are captured into the various tailings streams and returned to the mine area to refill the void.

The underflow from the constant density tank feeds into the wet concentrator plant at a rate of approximately 200tph of dry solids. Since the initial design the ilmenite flowsheet has been expanded to cope with the increased throughputs and the addition of a second ball mill.

The incoming feed, pre-screened to -1mm, using a double deck screen, results in a particle size distribution suitable for the wet concentrator and WHIMS which can accept mineral less than 2mm. The overflow from the secondary desliming cyclone reports to the 16metre thickener while the underflow flows into the CD tank which feeds the primary spirals in the gravity concentration circuit.

The concentrator feed is processed through one of two spiral concentrator plants in parallel each configured as a four stage circuit employing a conventional heavy mineral sands gravity separation technique. In the first stage (primary circuit), a super concentrate is generated which flows directly to the WHIMS circuit feed pump while the concentrate stream is diverted to the upgrade circuit for further cleaning. The middlings stream flows into the middlings circuit slurry bin and tailings from the primary circuit is routed to the scavenger. The concentrate from the middlings circuit is pumped to the upgrade circuit while the middlings is recirculated. The concentrate from the scavenger circuit feeds into the middlings circuit. Final concentrate is made up of the super concentrate from the primary circuit and concentrate steam from the upgrade circuit. The final tails are made up of tailings from the middlings circuit which is combined with the middlings and tailings from the scavenger circuit.

The majority of the feldspar and some of the apatite are rejected in the primary concentration circuit. Apatite has a higher sg (3.3) than feldspar (2.7) and so tends to report to the spiral concentrate with the ilmenite. The concentrate from the gravity circuit is routed to a two stage low intensity magnet (LIM) separator in a non- mags cleaner configuration where the highly susceptible material (magnetite) is rejected to tailings. The non- magnetic stream passes through an up current classifier with the overflow, which contains the -180micron material, being pumped to the medium intensity magnetic separator (MIMS) via a cyclone. The non-magnetic mineral from the MIMS flows into a wet high intensity magnetic separator (WHIMS) with the magnetic product being fed into a secondary WHIMS. The magnetic stream from the secondary WHIMS flows into the ilmenite final product bin while the middlings are recirculated. The non-magnetics streams from both stages of WHIMS, comprising mostly apatite, are routed to the final WHIMS stage via a cyclone, with the non-magnetic fraction from this stage feeding into the apatite circuit. The magnetics fraction from the final WHIMS stage is routed back to the classifier feed bin.

The +180micron material which reports to the underflow of the up current classifier containing the agglomerated ilmenite/apatite particles is fed into one of two ball mills operated in parallel with the objective of breaking up the particles to liberate the ilmenite grains. The product from the ball mill is routed to the slurry bin ahead of the MIMS via a cyclone. Feeding of WHIMS with pre-classified material is critical, and product recoveries are dependent on this. The ability to mill more intensely is key to achieving ilmenite product quality and maximising recovery, although this will be mitigated by the current mine plan which only mines CS (clay sand) ore.

The magnetics fraction from the WHIMS plant comprising the ilmenite concentrate produced is stockpiled via a cyclone and drained before being fed into the ilmenite drying plant while the non-magnetics fraction is diverted to the apatite circuit for further upgrading. The drying plant consists of a vacuum filter and gas fired vibrating fluid bed dryer where the ilmenite is dried and fed into the ilmenite product silo before being loaded onto a truck for transport to the port of Gladstone.

The feed to the apatite circuit passes through a further stage of WHIMS (narrow rotor) with the magnetic fraction diverted to the final tailings bin. In the current plant configuration the non-magnetic fraction is pumped to a single final spiral gravity separation stage. The tailings from the gravity circuit are diverted to final tails while the middlings are recirculated to the apatite circuit feed bin.

It is currently proposed that the unused wet shaking tables, previously employed in the feldspar circuit, be incorporated into the apatite circuit to improve recovery. In the planned upgraded circuit the feed into the apatite circuit will pumped into an up current classifier operated at 100micron cut point. The +100micron underflow will be passed over a 300micron screen with the -300micron undersize being fed onto the coarse wet shaking table. The overfllow from the up current classifier feeds directly onto the fines shaking table. The concentrate streams generated by the wet tables are combined to produce the 32% P2O5 product while the lighter minerals are rejected as tailings. The magnetic rejects and table tailings streams are combined and pumped into the final tailings bin. The final process flowsheet for the upgraded circuit will be confirmed after the restart and necessary modifications made to the pipework and equipment configured.