Efficient extraction of aluminum from leaching solutions of waste alnico alloys by CA12-N235 system

Waste alnico alloy contains valuable metals of aluminum, nickel and cobalt. Recycling of these metals is of great importance from the perspective of resource utilization. In this study, we present a green and efficient extraction system to separate aluminum from nickel and cobalt in the leaching solution of waste alnico alloy. Using the CA12-N235 system consisting of 30 vol% CA12, 25 vol% N235 and 45 vol% kerosene as the extractant, nearly 100% aluminum was extracted while only 6.1% cobalt and 6.7% nickel were co-extracted after two-stage extraction. The nickel and cobalt in the loaded organic phase were scrubbed completely by two-stage scrubbing with water. The high purity aluminum was obtained in the strip liquor through one-stage stripping with 0.5 mol/L hydrochloric acid solution. Infrared spectroscopic analysis and slope analysis revealed that the composition of the extracted complex was (C8H17C6H4OCH2 COO)3Al, which was bound via hydrogen bonding with R3NH+ produced from the reaction between N235 and H+. Na-saponified CA12 has a high extraction capacity for aluminum, with single-stage extraction efficiencies of 99% for aluminum, 6.7% for cobalt and 8.2% for nickel, but has difficulty in phase separation. CA12-N235 system has advantages of high extraction capacity for aluminum and quick phase separation compared with naphthenic acid and P507.