Effects of Cations/Anions in Recycled Tailing Water on Cationic Reverse Flotation of Iron Oxides

Abstract

It is well known that reverse flotation performance of iron oxides is affected by water quality. Since many potential variations among water sources recycling in a mineral processing plant bring unpredictable effects on the flotation system of iron oxides: disturbing ions/compounds, pH, hardness, residual reagents, etc. In this study, the recycled tailing water from a local plant, characteristically constituting of Ca2+, Mg2+, Na+, K+, Al3+, Fe3+, Cl−, SO42− etc., was introduced into the cationic reverse flotation process of an iron ore. A series of bench flotation tests using iron ores, micro-flotation tests using pure fine quartz, water chemical analyses, and zeta potential measurement were conducted with the objective of identifying the possible influences of both cations and anions in the recycled tailing water on the flotation performance. The flotation results pointed out that the cation with higher valency had more severe influences on the recovery of iron oxides. The formation of the pH-dependent surface complexes on mineral surfaces, for example, Fe(OH)+, Fe(OH)2+, and Fe(OH)3 resulted from Fe3+ ions adsorption, contributed to the less negative zeta potentials of the quartz, and consequently weakened its interaction with the amine collector. It is worthy to note that SO42− ions seem to have a more positive effect on the recovery of iron oxides than Cl− ions. This is probably attributed to the formation of inner/outer- sphere surface complexes on the iron oxides, inhibiting the dissolution of the iron ions/species, and the coordination with these cations from the recycled tailing water, shielding their disturbances in the flotation.

Collecting Agent–Mineral Interactions in the Reverse Flotation of Iron Ore: A Brief Review

“…Only a couple of studies placed an emphasis on the role of anions in plant water. It was found that an anion in water has a greater depression than a cation at the same charge in the flotation of hematite, and an increase in the valence of anion leads to a drop in the adsorption of oleate on hematite [42,43].…”

“…The concentration of cations can be very high after accumulation in the process water and significantly depress the flotation of quartz when cationic collectors are used. As shown in Figure 7, the adsorption of metal cations on quartz surface can reverse the surface charge from negative to positive, which prevents the adsorption of cationic amine on the quartz surface owing to electrostatic repulsion [43,71]. Hence, the concentration of metal cations in process water should be closely monitored.…”

“…Different from cations, anions exhibit a promotive effect on the reverse flotation of iron oxides, in improving the recovery of Fe and lowering the SiO 2 content in the concentrate. This is probably owing to the formation of the inner and outer sphere binuclear or polynuclear surface complexes on mineral surfaces at near-neutral pH values, providing less suitable leaving groups for detachment into the water, thus successfully inhibiting the dissolution of metal ions with a higher valence [43]. In addition, anions at a higher valence (e.g., SO 4 2− ) tend to have a more significant effect than anions with a lower valence (e.g., Cl − ) [73].…”

Treatment of Highly Concentrated Fluoride Wastewater from the Semiconductor Industry by CaCl2 based on the Adjustment of ζ-Potential

“…As shown in Figure , with the increase of Ca 2+ addition, the ζ potential kept steady ( n (Ca 2+ )/ n (F – ) = 0.55–0.6), then increased obviously ( n (Ca 2+ )/ n (F – ) = 0.6–0.7), and went steady at last ( n (Ca 2+ )/ n (F – ) > 0.7). The increase of ζ potential may be due to the replacement of Na + by Ca 2+ on the surface of the micelle . The increase of ζ potential can enhance the electrostatic rejection force between micelles, which would prevent the reunion of CaF 2 to be a precipitant.…”

“…The increase of ζ potential may be due to the replacement of Na + by Ca 2+ on the surface of the micelle. 21 The increase of ζ potential can enhance the electrostatic rejection force between micelles, which would prevent the reunion of CaF 2 to be a precipitant. However, with the increase of CaCl 2 addition, the F − removal ratio increased obviously.…”