Effects of metallic ions on fine-grained phosphate-rock particle dispersion and aggregation

Abstract

With the rapid development of the phosphorus chemical industry and the new energy industry, the role of phosphate rock is becoming more and more prominent. Medium and low phosphorus ore has gradually become a research hotspot. The stable dispersion of fine-grained phosphate rock in pulp is the premise of effective flotation. To elucidate the mechanism through which fine-grained phosphate-rock particles disperse and aggregate in pulps, we used solution chemistry, Derjaguin–Landau–Verwey–Overbeek theoretical calculations, zeta-potential measurements, and x-ray photoelectron spectroscopy to investigate the effects of Ca2+, Mg2+, Fe3+, and Al3+ metallic ions on the dispersion stability during the flotation of medium- and low-grade phosphate-rock particles. The experimental results showed that as the pulp pH changed, the metallic ions differently inhibited the particle dispersion stability. The trivalent metallic ions (Fe3+ and Al3+) inhibited the particle-dispersion stability more strongly than the divalent ones (Ca2+ and Mg2+) and strongly inhibited the particle dispersion stability in pH ranges >10 and 4–10, respectively. Correlation analysis and calculations revealed that in a certain pH range, metallic ions in the pulp generated corresponding hydroxyl complexes or precipitates, which adsorbed on the mineral-particle surfaces, reduced the potential energy of interparticle interactions and enhanced the particle aggregation, thereby inhibiting the dispersion stability.