Optimization of spodumene flotation with a fatty acid collector

Abstract

An increasing demand for lithium-ion batteries is driving the development of new lithium mineral projects. Spodumene, a major lithium-bearing mineral found in pegmatite deposits, is often recovered by froth flotation. The primary collectors in spodumene flotation are fatty acids which are known for their poor selectivity. Fatty acid collectors tend to recover common gangue minerals in spodumene deposits due to their similar surface properties, making it difficult to produce high-grade concentrates with high lithium recovery. The ionic collector behavior is sensitive to pulp conditions like pH and concentration, but there is a weak understanding of this behavior during conditioning. There is a consensus that the conditioning stage is vital to flotation performance and should be conducted at high pulp-density (∼60% solids) to ensure proper collector adsorption. If not executed properly, rougher flotation suffers, making it challenging to achieve high final concentrate grades and recovery. This study uses a central composite experimental design and linear regression analysis to investigate and model the effects of four parameters of high-density conditioning with fatty acids on the responses of rougher concentrate grade and recovery: initial pulp pH, collector dosage, conditioning time, and power density. The models developed for both responses were determined to be statistically significant in the tested region. Initial pulp pH, collector dosage, and power density were significant terms in both models, while conditioning time was insignificant. Increased power density, ∼31 W/L, was necessary to achieve high rougher concentrate grades but increasing beyond 37 W/L was harmful to recovery. In general, higher collector dosages (>500 g/t) resulted in high recoveries, but initial pH must be adjusted accordingly to maintain concentrate grade. The most robust conditions to achieve > 90% recovery at a concentrate grade > 5.5% Li2O with this material were determined to be 31 W/L energy input and 625 g/t collector at an initial pH of 8.25. The flotation performance in this study is strongly connected to the behavior of fatty acid collectors reported in the literature and the findings provide good insight for operators and researchers aiming to improve spodumene flotation performance with fatty acids.