Sunrise Nickel Cobalt Project, New South Wales, Australia NI 43-101 Technical Report Section 26 Page 392
Autoclave feed rheology Rheology testwork has indicated that the Sunrise ores exhibit variable rheology between 45%w/w and 48%w/w solids, with the yield stress often increasing with time (shear thickening).
It is recommended that further variability testing is undertaken to demonstrate that the currently proposed autoclave feed solids density of 45%, coupled with a coarser top size target of 500μm and elevated temperature (60 – 70C) will produce the desired rheology after going through the shear thinning process proposed in the plant design.
High pressure acid leach process There is now a high degree of confidence in the robustness of the HPAL process to extract nickel and cobalt from lateritic ores, and extensive testing has been undertaken on the Sunrise ores. However, the current owners of the project have not demonstrated the high recoveries of nickel (95.7%) and cobalt (95.0%) that have been predicted at pilot scale, although former owner pilot testing and extensive batch testing by Clean TeQ has indicated these recoveries are possible. It is recommended that the pilot plant operation commenced in July 2018 ensure that the nickel and cobalt recoveries in the process design criteria are confirmed at pilot scale.
Continuous Resin-in-pulp (cRIP) process The process chemistry has been developed over many years now and has been proven in both uranium and gold operations. The testing undertaken by Clean TeQ has confirmed the resin chemistry for the current requirements and has not identified any issues that cannot be successfully managed. In addition, extensive pilot testing was undertaken with BHP to confirm the process suitability (both chemical and mechanical) for nickel laterite ores. Although further large-scale pilot testing is always desirable, this reviewer believes that the process is viable, and the process design criteria with regard to resin stability and replacement requirements are sufficiently conservative to cope with any unforeseen issues with regard to the mechanical and chemical stability of the resin.
One outstanding issue that remains is for the extent to which the cRIP process can recover nickel, cobalt and scandium that has been precipitated during the partial neutralisation process. A recovery factor of 20% for nickel and cobalt, and 40% for scandium, has been applied based on recent testwork that had issues with pH control in the cRIP circuit. It is recommended that these percentage recoveries for all metals be confirmed for continuous processing using a resin pre-treated to achieve the correct pH balance in the cRIP circuit.
Downstream Processing The extensive testwork undertaken by Clean TeQ over the last 18 months has mostly been enough to support the detailed design of the Sunrise Ni/Co Project. The design parameters are also supported by industry practice for nickel and cobalt solvent extraction operations which are well established. The testwork adequately demonstrated that battery grade nickel and cobalt sulphates can be produced from the Sunrise ores, and the partial recovery of scandium, although only partially factored in to the process financial analysis, remains a project upside that may expand over time.
I don't see any evidence of these issues being addressed. Can anyone shed more light here?
