Polymer-Assisted Tailings Dewatering in Seawater and Continental Water for Copper Flotation

TL;DR

This study explores using seawater and continental water for dewatering and copper flotation in mining, showing how water chemistry affects polymer performance and copper recovery.

Contribution

The study introduces polymer-assisted dewatering methods optimized for seawater and continental water in copper flotation, improving water reuse in arid mining regions.

Findings

Anionic polymer A3 increased settling rates 33 times with continental water and 31 times with seawater.

Using seawater in thickening reduced water usage by ~17,000 m3 annually.

Recirculated and filtered seawater improved copper recovery by 3–5%, while continental water reduced recovery by 2–4%.

Abstract

This study evaluates the use of seawater and continental water in tailings thickening and copper flotation at laboratory scale, focusing on water reuse in mining operations in arid regions. The tailings had a mean particle size of 10 µm, with 75% < 50 µm, and a specific weight of 2.64 g/cm3. Seawater contained significantly higher ion concentrations Na+ 10,741 ppm, Mg2+ 1245 ppm, and Ca2+ 556 ppm compared with continental water (187, 32, and 127 ppm, respectively), which negatively affected polymer performance. Sedimentation tests showed that the anionic polymer (A3) increased settling rates by 33 times with continental water at 40 g/t, while with seawater the increase was 31 times at 60 g/t. In column thickener tests, discharge solids reached 65% with continental water and 62% with seawater, representing an annual reduction of ~17,000 m3 of recovered water when seawater is used. Consistency tests indicated that achieving slump <20% required 75% solids with continental water and 77.5% with seawater. With dewatering polymers, doses of 200 g/t achieved ~70% solids and slump values near 50%, surpassing column thickener performance. Primary flotation results showed that recirculated and filtered seawater improved copper recovery by 3–5% compared with fresh seawater, due to partial removal of interfering ions. In contrast, recirculated and filtered continental water reduced recovery by 2–4%, likely because of residual polymer effects on mineral surfaces. These findings highlight the importance of polymer selection and dosage optimization to ensure efficient water recovery and sustainable flotation performance under varying water chemistries.

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