Spodumene and Lepidolite Flotation Techniques

Composition: Contains 4.5–8% Li₂O, critical for lithium extraction in batteries and ceramics.
Flotation Challenges:

Surface Sensitivity: Pure surfaces float readily with oleic acid, but mud contamination or weathering reduce hydrophobicity.
Ion Interference: Dissolved Cu²⁺, Fe³⁺, and Al³⁺ in pulp activate both spodumene and gangue, necessitating pre-flotation desliming and alkali treatment.

Reagent/Parameter	Role	Recommended Range
pH Adjustment	Use NaOH or Na₂CO₃ to suppress gangue and enhance selectivity.	pH 7–7.5 (neutral-weakly alkaline)
Collector	Oleic acid (most effective) or naphthenic acid for hydrophobic bonding.	500–1,000 g/t (adjust for ore grade)
Regulators	Sodium fluoride (activator) + lignosulfonate (dispersant).	Fluoride: 200–500 g/t; Lignosulfonate: 100–300 g/t
Stirring Intensity	Higher speed (7x increase) boosts recovery by 40% via improved particle-collector contact.	1,500–2,000 RPM (vs. standard 200–300 RPM)
Particle Size	Optimal <0.15 mm; recovery drops to 22% at 0.3 mm due to poor bubble attachment.	-0.15 mm (-100 mesh)

Strong Inhibitors: Water glass, dextrin, starch (starch shows highest selectivity for spodumene suppression).
Effect: Starch inhibits spodumene first, then gangue; water glass lacks selectivity, suppressing both minerals.

Composition: Contains 1.2–5.9% Li₂O, often recovered from fine-grained deposits.
Processing Flow:

Coarse Fraction: Hand sorting, winnowing, or friction separation for pre-enrichment.
Fine Fraction: Flotation using cationic collectors.

Reagent/Parameter	Role	Optimal Conditions
Collector	Octadecylamine (primary choice) for electrostatic adsorption on mineral surface.	Dosage: 100–300 g/t; effective in acidic (pH 4–6) and neutral (pH 7–8) media.
Activation	Hydrofluoric acid (HF) removes surface oxides, enabling oleic acid adsorption on unactivated minerals.	HF: 50–100 g/t (pre-conditioning step).
Inhibitors	Iron/aluminum/lead salts, Na₂S, starch, Na₂HPO₄ suppress lepidolite flotation.	Starch + Na₂S + bleaching powder: strongest combined inhibitor for gangue rejection.
Activators	Li₂CO₃ or Li₂SO₄ enhance surface charge compatibility with collectors.	Dosage: 200–400 g/t (adjust based

Acid/Neutral Media: Octadecylamine performs best at pH 4–8, avoiding hydroxide precipitation of metal ions.
Metal Ion Effects: Cu²⁺, Al³⁺, and Pb²⁺ sulfates activate lepidolite, while nitrates inhibit flotation.

Pre-Flotation Preparation:
- Deslime using hydrocyclones or screens to remove <20μm colloidal clays.
- Adjust pulp pH and reduce dissolved metal ions via alkali conditioning (e.g., NaOH).
Reagent Sequencing:
- Add depressants (e.g., starch) before collectors to suppress gangue (e.g., quartz, feldspar).
- For lepidolite, use HF activation prior to cationic collector addition.
Particle Size Control:
- Grind spodumene to <0.15 mm; employ regrinding for coarse particles to improve liberation.
Environmental Considerations:
- Manage HF and cyanide-containing wastewater via neutralization and chemical precipitation.
- Use starch-based inhibitors for biodegradability and reduced ecological impact.

Spodumene: Prioritize fine grinding, pH optimization (7–7.5), and oleic acid-based collectors with fluoride activation.
Lepidolite: Leverage cationic collectors (e.g., octadecylamine) in acidic/neutral media, with HF pre-treatment for refractory ores.
Testing: Conduct bench-scale flotation tests to validate reagent dosages and particle size targets for specific ore types.