Eco-Friendly Collectors for Flotation of Fine Hematite and Malachite Particles

Abstract

The separation of fine mineral particles, especially using environmentally friendly approaches, is one of the main problems in the processing of low-grade ores and the re-processing of mining tailings. This work assesses the potential of biosurfactants as collectors in the flotation of ultrafine (smaller than 20 μm) particles of hematite and malachite. As biosurfactants, we test acetylated acidic (ac-ASL) and lactonic sophorolipids (ac-LSL). In addition, n-dodecyl-β-D-maltoside (DDM) is used as a model non-ionic alkyl disaccharide surfactant, and sodium oleate (NaOl) is used as a reference. The biosurfactants are characterized using surface tension and foam analysis. The interaction of the minerals with the surfactants is characterized using zeta potential, solubility, and single-mineral flotation. The collecting properties of the surfactants are compared for the ultrafine (− 20 μm) and coarser (38–90 µm) particle size in the two-mineral flotation of hematite and malachite against quartz. The ultrafine particle size improves the grade in the oleate flotation of hematite, as well as the grades in the DDM flotation of hematite and malachite, which is explained by the weak interactions of the metal oxides with fatty acids and DDM. At the same time, the flotation with ac-LSL and ac-ASL is highly tolerant to the ultrafine particle size. These results indicate that biosurfactants are an interesting alternative to conventional petroleum-based surfactants in the flotation of Fe and Cu oxides. Moreover, a proper selection of surfactants can help combat the problem of fines. Graphical Abstract

Quartz Fine Particle Processing: Hydrophobic Aggregation by Shear Flocculation

“…This fact suggests that hydrophobicity is the factor that plays the main role in shear flocculation. Further in-depth information regarding the mechanisms can be found elsewhere [44][45][46]. In Figure 7, it is evident that the highest aggregation of quartz particles occurred at pH 10.5, suggesting the importance of the non-dissociated amine molecules in quartz hydrophobization [34].…”

“…This fact suggests that hydrophobicity is the factor that plays the main role in shear flocculation. Further in-depth information regarding the mechanisms can be found elsewhere [44][45][46].…”

Flotation of Sulphide Minerals Using Organosolv Lignin as Collector—Pilot-Scale Trials

“…Furthermore, xanthates present moderate stability, causing quality deviations, with an unexpected impact on the flotation performance [4]. As a consequence of the aforementioned concerns, there is an increasing trend in the replacement of xanthates with safe and eco-friendly chemicals in the flotation process [5,6].…”