Image Resources NL (ASX: IMA) has announced an inaugural dredge mining Mineral Resources estimate of 102 million tonnes at 2.2% total heavy minerals for the Company’s Bidaminna Minerals Sand Project located 100 km north of Perth in the North Perth Basin.
IMA reported high-value mineral assemblage (as % of HM) with 36% leucoxene (70-95% TiO2), 5% zircon (premium grade), 4% rutile (95% TiO2), and 48% ilmenite (50-70% TiO2).
The company also reported 93% valuable heavy mineral (VHM) assemblage in HM, very low slimes (3.3%) and oversize (2.2%), and a low strip ratio. Image said that much of the mineralisation is below the water table and amenable to lower-cost dredge mining.
The company reported that the mineral recovery testwork indicated high TiO2 recoveries of 92% in wet process and 99% in dry separation.
Inaugural dredge mining MRE at Bidaminna
The company said that Optiro Pty Ltd has completed an inaugural dredge mining Mineral Resource estimate for Bidaminna that has been classified and reported in accordance with the guidelines of the JORC Code (2012).
The historic 1992 Bidaminna Dry Mining Mineral Resources summary reported above a 2.0% total HM cut-off grade is as shown below.
Total tonnes jump 129%
IMA announced that the total tonnes of Mineral Resources have more than doubled from 44.6 million to 102 million tonnes when compared to the 1992 historic MRE for Bidaminna as a dry mining prospect. The company said that the new MRE also reported substantially increased higher-value leucoxene and rutile content, albeit at a lower total HM grade.
Image said that the interpreted strandline mineralisation for this Mineral Resources estimate covers a strike length of 9.5 km, with mineralisation open to the north. Meanwhile, depth of mineralisation ranged from as shallow as 12 metres at the top of the upper strandline, to 66 metres at the bottom of the lower strandline.
2021 Bidaminna Dredge Mining Mineral Resources summary reported above a 0.5% total HM cut-off grade is as shown below.
The company noted that the main reasons for the substantial increase in Mineral Resource tonnes reported in 2021 are the inclusion of additional drilling, compositing, and analysis conducted by Image in 2017-2019; and the incorporation of a lower cut-off grade applicable to lower cost dredge mining (0.5% total HM for dredge mining versus 2.0% total HM for dry mining).
Mineral recovery testwork confirms high TiO2 recoveries
Image said that initial mineral recovery testwork was conducted by Allied Mineral Laboratories on a 100 kg composite sample derived from exploration drill samples representing a blend of the upper and lower mineralised strandlines across two drill lines in the northern half of the deposit.
92% recovery from wet separation
IMA reported that the mineral recovery test results confirmed that the medium coarseness of the mineralisation (D50 of 100-110 micron), low slimes content (<4%), and absence of particle agglomerations, resulted in high mineral recoveries of 92% of contained TiO2 and 95% of contained zircon from simple wet separation processing using standard spirals.
99% recovery from dry separation
The company announced that the follow-on dry separation testing to achieve final products also indicated efficient separation and high recoveries of 99% of TiO2 minerals and recovery of greater than 70% of zircon as premium grade at >66% ZrO2+HfO2.
IMA noted that TiO2 minerals were further separated to produce ilmenite (72% of mass at 58% TiO2), low-grade leucoxene (20% of mass at 66% TiO2), and high-grade leucoxene (7% of mass at 83% TiO2).
Bidaminna to remain in focus
The company said that the focus on Bidaminna continues to be as a potential future mine development centre that would operate as a stand-alone production centre, operated in parallel with existing dry mining operations.
IMA said that dry mining is currently being conducted at Boonanarring, but with planning in place for relocating mining and processing to the Atlas Project area as early as in the December quarter of 2022.
The company said that depending on the progress and positivity of Bidaminna feasibility studies, project economics, access approvals, all necessary permitting for construction and mine operations, and project funding, the development timeline could be as little as three years following initial feasibility results.
Much of the Bidaminna mineralisation is below the water table and, as such, is being considered for bulk mining by a dredge operation and this cut-off grade was selected by Image based on technical and economic assessment and on comparison with similar deposits currently or recently having been mined.
IMA said that next steps would include incorporating this Mineral Resources estimate with initial scoping study work conducted by Mineral Technologies and later with pre-feasibility study work currently being planned. A third step would be a definitive feasibility study.
The company announced that an infill drilling programme is planned to upgrade the Inferred Mineral Resources to an Indicated or Measured classification. IMA said that additional composite sampling and mineral assemblage analysis, and further mineral recovery testing and final product quality testing will be used to support a feasibility study.
*Image Source: Image Resources NL