Selective flocculation-flotation of fine spodumene with anionic polyacrylamide flocculant and calcium activator

• First report of flocculation-flotation of fine spodumene using polyacrylamide flocculants. • Premixing NaOl collector with polymer enables cooperative adsorption and ∼ 60° contact angle. • Recovery increases from ∼ 25 % (no polymer) to ∼ 72 % (premixed) at ∼ 70 % grade. • Polymer charge density of 58–90 % optimises quartz rejection through electrostatic repulsion. • Contact angle data provides supporting evidence for competitive vs. cooperative adsorption. Fine spodumene particles are typically lost to tailings during desliming in conventional flotation circuits. This study presents the first investigation of selective flocculation-flotation as a method to recover fine spodumene using high-molecular-weight anionic polyacrylamide (PAM) flocculants with calcium activation and sodium oleate (NaOl) collector. Using a synthetic ore mixture of fine spodumene and quartz (30 wt% spodumene, d 50 values of 22 µm and 11 µm respectively), the effects of pH, Ca(II) dose, collector dose, flocculant dose, flocculant charge density and reagent addition sequence were systematically examined. A key finding is that premixing the flocculant and collector prior to addition substantially enhances flotation performance compared to sequential reagent addition. Contact angle measurements reveal that this premixing produces cooperative rather than competitive adsorption, increasing the spodumene contact angle from ∼ 45° (sequential) to ∼ 60° (premixed), consistent with the formation of polymer–NaOl complexes that deliver both aggregation and hydrophobicity simultaneously. Under optimal conditions (pH 8.5, 625 g/t Ca(II), 6000 g/t NaOl, 80 g/t PAM with 90 % anionic charge), flocculation-flotation achieved a spodumene recovery of 72 % at a grade of 70 % (5.6 % Li 2 O), compared to 25 % recovery at 82 % grade (6.6 % Li 2 O) without polymer. These findings demonstrate that flocculation-flotation can recover fine spodumene that would otherwise be discarded, with polymer charge densities of 58–90 % providing the best selectivity against quartz through electrostatic rejection of the negatively charged gangue.