Targeted mica recovery can improve circuit efficiency
Typical pegmatite ore consists of spodumene (LiAl(SiO3)2) with gangue minerals quartz, feldspar and mica. A fatty acid is used to recover spodumene; however, this collector also floats mica. To manage this, operations rely on a pre-flotation stage, where mica is removed using an amine collector ahead of spodumene flotation.
In practice, however, conventional amine collectors used in the prefloat are not selective, recovering not only mica but also significant amounts of quartz and feldspar. This is not ideal, and an argument can be made that developing an amine that is selective towards mica in the prefloat could be beneficial for reducing mass pull, possibly reduce spodumene losses and limit potential amine carryover into the spodumene fatty acid circuit.
This study evaluated the performance of a selective amine collector, designed to preferentially recover mica while limiting flotation of other gangue minerals.
A more selective approach
Flotation test work compared a novel amine-based collector (Nascol CZZ1) with a conventional amine (EDA). Tests were conducted on a representative lithium-bearing ore using standard rougher conditions (pH 2.5, 10-minute flotation, 2.5L Denver cell), across a range of collector dosages.
Nascol CZZ1 consistently improved mica recovery by approximately 6% relative to EDA. Notably, comparable mica recovery was achieved at 100g/t of Nascol CZZ1 to that obtained with 300g/t of EDA. This improved efficiency at lower dosage offers both a potential cost advantage and reduces the risk of amine carryover into the downstream fatty acid circuit. Importantly, this improved recovery did not result in increased quartz and feldspar recovery.
Quartz and feldspar recovery were significantly reduced across all dosages (by up to 22% at 100g/t). This demonstrates that the reagent preferentially targets mica while limiting the recovery of quartz and feldspar.
Impact on spodumene losses in prefloat
The benefit of improved selectivity becomes evident when considering spodumene losses in the mica prefloat.
A strong relationship was observed between quartz/feldspar recovery and spodumene reporting to the pre-float. The figure demonstrates that spodumene recovery is largely due to entrainment and entrapment. Limiting quartz and feldspar recovery lowers mass pull, thus reducing the amount of entrapped spodumene particles.
Due to this relationship, spodumene losses in mica prefloat are approximately 13% less compared to EDA at 100g/t.
This improvement has important downstream implications. Cleaner performance is sensitive to both solids loading and the extent of value mineral that needs to be recovered. By reducing mass pull and the carryover of entrained spodumene, the cleaner circuit operates under less constrained conditions, improving its ability to reject gangue and recover spodumene, making the cleaner more robust.
Developing an amine that is selective toward mica in the prefloat is beneficial because:
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Reduced mass pull
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Potentially lower spodumene losses
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Reduced potential amine carryover into the spodumene fatty acid circuit
The key takeaway
This work demonstrates that Nascol CZZ1 functions as a selective mica collector. By increasing mica recovery while limiting the recovery of quartz and feldspar to the pre-float, overall mass pull is reduced, thereby minimising entrainment and entrapment of spodumene. As a result, spodumene losses to the mica pre-float are significantly lower (approximately 13%).
Importantly, the increased mica recovery also suggests that similar or improved performance can be achieved at lower reagent dosages. This not only offers a potential cost advantage but also reduces the risk of amine carryover into the fatty acid circuit, supporting more stable and selective downstream flotation.
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