Assessment of the selective flotation of calcite, apatite and quartz using bio-based collectors: Flaxseed, nigella, and olive oils

Abstract

• Bio-based collectors were tested in a FAp/Cal/QTZ flotation system. • The collector’s dosage and composition control the adsorption. • pH and mineral dissolution impact the adsorption mechanism. • The collectors had more affinity towards calcite . • Flaxseed oil collector allowed the recovery of 95.7% calcite. Bio-based flotation reagents are of great interest considering their low-cost, abundance, and sustainability. This study evaluates the performance of saponified vegetable oils as collectors in phosphate ores’ flotation. Olive, nigella, and flaxseed oils were elected for their fatty acid composition and their local availability. Prior to saponification, the oils’ acidity index, saponification value, and fatty acids profile were determined. Surface chemical characterization, adsorption quantification and isotherms, zeta potential, and wettability assessments were conducted on bare and treated pure fluorapatite, calcite, and quartz. At low collector dosages, results revealed the chemical adsorption of the synthesized collectors on calcite and fluorapatite surfaces. With increasing dosages, the collectors’ molecules precipitated at the calcium-bearing minerals’ surface as calcium dicarboxylates salts then as micelles of fatty acids. Furthermore, flaxseed’s soap exhibited higher adsorption densities and significant contact angle increases on the surface of calcite (8.20 mg/m 2 and +32.93°) compared to fluorapatite (2.43 mg/m 2 and +3.65°). Moreover, collectors’ adsorption on the surface of quartz was minimal. Accordingly, flaxseed’s soap, served as an efficient calcite collector in phosphate flotation while including phosphoric acid for apatite depression. It enabled the recovery of up to 95.7% calcite at pH 12.