Optimization of spodumene flotation with fatty acid collectors

At present, hard-rock minerals like spodumene (LiAlSi2O6) – concentrated by dense media separation (DMS) and/or froth flotation – represent >50% of global lithium production. A major process challenge in spodumene beneficiation is poor flotation selectivity stemming from insolubility of the tall oil fatty acid (TOFA) collectors. Studies from the 1960s first reported that high density conditioning improved TOFA flotation performance, but collector properties and adsorption behaviour throughout conditioning remain poorly understood. Based on these challenges, the objective of this project was to investigate the impact of three process components on spodumene flotation performance: (1) High-density conditioning operating set-points (agitation power density, time, collector dosage, and pulp pH behaviour); (2) NaOH scrubbing/activation time; and (3) the level/type of rosin acid impurities in commercial TOFA collectors. A Central Composite Design (CCD) of experiment investigated conditioning parameters and pH behaviour, which later guided collector adsorption studies using Time of Flight-Secondary Ion Mass Spectroscopy (ToF-SIMS) and X-ray Photoelectron Spectroscopy (XPS). Significant conditioning parameter relationships were identified and combined to improve rougher concentrate grade from 4.9 to 5.3% Li2O while maintaining 97% lithium recovery at a higher power density (37 W/L) with reduced initial pH (8.2) and conditioning time (7 minutes). ToF-SIMS analysis identified decreasing molecular TOFA on spodumene surfaces as the conditioning progressed, which corresponded to increased selectivity and decreased recovery, revealing ideal molecular acid physisorption is needed for successful flotation. The benefit of NaOH scrubbing was highlighted through batch flotation testing; recovery increased significantly after 10 minutes of scrubbing and was maintained while the concentrate grade increased as scrubbing progressed to 180 minutes. X-ray Adsorption Near Edge Spectroscopy (XANES) studies of NaOH scrubbed spodumene samples identified changes in the Li and Al bonding environments that aligned with the flotation behaviour. The impact of higher rosin impurities (>1%) in TOFA collectors was confirmed to reduce flotation selectivity and provided some indication that a higher PAN (palustric, abietic, neoabietic acid) number may contribute to increased recovery of iron-bearing gangue minerals. Overall, this project demonstrates the challenges of spodumene flotation, while presenting several physiochemical approaches to improving flotation performance and expanding the understanding of collector-particle behaviour during high-density conditioning.

Department dc:contributor.department

Mining Engineering

Year dc:date.issued

2025

Author dc:creator

• Cook, Brian Kawenski

Advisor dc:contributor.supervisor

• Gibson, Charlotte

• Lithium
• Spodumene
• Flotation
• Minerals Processing
• Tall Oil Fatty Acids

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1974/34272

OAI identifier oai:identifier

oai:queensu.scholaris.ca:1974/34272