Iron Ore Beneficiation through Reverse Flotation: Advances in Nanobubble-Assisted Flotation Technology for Lean Grade Ore Upgradation and Silica Removal: A Review

Year : 2026 | Volume : 03 | Issue : 01 | Page : 1 30
    By

    Mihir D.M.,

  • Attel Umasanka,

  1. AGM, BHQ Operations, R&D, JSW Steel, Vijayanagar works, Toranagallu, Bellary,, Karnataka, India
  2. Head BHQ Projects, JSW Steel, Vijayanagar works, Toranagallu, Bellary,, Karnataka, India

Abstract

The global demand for high-grade iron ore concentrates continues to surge as readily available rich ores become depleted. Iron ore beneficiation through froth flotation has emerged as a critical technology for upgrading lean-grade iron ores (typically 25–35% Fe) to produce high-quality concentrates (64–70% Fe) suitable for direct reduction and blast furnace operations. This comprehensive review examines the fundamental principles of flotation in iron ore beneficiation, with particular emphasis on the revolutionary impact of nanobubble (NB) assisted flotation technology. Nanobubbles, ultrafine bubbles with diameters ranging from 300 to 700 nm, offer unprecedented advantages in enhancing flotation kinetics, collector adsorption efficiency, and mineral selectivity for the separation of fine and ultrafine particles. This paper synthesizes the current state of the art in nanobubble generation via hydrodynamic cavitation, the mechanisms of nanobubble-enhanced flotation, surface chemistry fundamentals, and the critical role of reverse flotation (cationic and anionic) in silica removal from lean iron ores. Industrial case studies from global operations, process intensification strategies, and comparative analyses of nanobubble versus conventional flotation demonstrate improvements in iron recovery (20 to 40 percentage points), flotation rate acceleration (30 to 50%), and a significant reduction in reagent consumption. The paper addresses current challenges in processing Anshan-type ores and other refractory hematite deposits, discusses scale-up considerations, and projects future research directions in nanobubble-assisted flotation for sustainable iron ore beneficiation.

Keywords: Iron ore, flotation, nanobubbles, hydrodynamic cavitation, silica removal, lean grade ores, reverse flotation, surface chemistry, collector adsorption, mineral processing

[This article belongs to International Journal of Minerals ]

How to cite this article:
Mihir D.M., Attel Umasanka. Iron Ore Beneficiation through Reverse Flotation: Advances in Nanobubble-Assisted Flotation Technology for Lean Grade Ore Upgradation and Silica Removal: A Review. International Journal of Minerals. 2026; 03(01):1-30.
How to cite this URL:
Mihir D.M., Attel Umasanka. Iron Ore Beneficiation through Reverse Flotation: Advances in Nanobubble-Assisted Flotation Technology for Lean Grade Ore Upgradation and Silica Removal: A Review. International Journal of Minerals. 2026; 03(01):1-30. Available from: https://journals.stmjournals.com/ijmi/article=2026/view=243365


References

  1. Zhang, X.; Gu, X.; Han, Y.; Parra-Álvarez, N.; Claremboux, V.; Kawatra, S.K. Flotation of Iron Ores: A Review. Process. Extr. Metall. Rev. 2019, 41, 184–212.
  2. Wu, Z.; Huang, H.; Shao, H.; Tao, D.; Tao, Y. An Investigation of Approaches for Enhanced Reverse Flotation of Refractory Hematite Ore. Minerals 2023, 12, 2–16.
  3. Pattanaik, A.; Venugopal, R. Role of Surfactants in Mineral Processing: An Overview. In Surfactants in Tribology; Makhija, P., Ed.; IntechOpen: London, UK, 2017; pp. 1–40.
  4. Iwasaki, I. Flotation of Iron Ores. In Flotation: Theory, Reagents and Ore Testing; Fuerstenau, M.C., Ed.; AIME: New York, USA, 1976; pp. 125–180.
  5. Araujo, A.C.; Viana, P.R.; Peres, A.E.C. Reagents in Iron Ore Flotation. Miner. Eng. 2005, 18, 219–224.
  6. Colombo, B. Industrial Application of Cationic Reverse Flotation to Iron Ore Beneficiation. Miner. Eng. 1980, 33, 189–207.
  7. Edwards, D.A.; Kipkie, R.P.; Agar, G.E. Entrainment in Reverse Flotation Circuits. In Flotation of Sulfide Ores; Fuerstenau, M.C., Ed.; SME: Colorado, USA, 1980; pp. 110–142.
  8. Emmanuel, A.; Fonseca, A.; Leal-Quiñonez, J. HPGR in Iron Ore Concentration: Impact on Liberation and Flotation. J. Miner. Process. 2019, 158, 45–62.
  9. Tripathy, S.K.; Banerjee, P.K.; Suresh, N. Desliming Studies in Iron Ore Flotation: An Overview. Powder Technol. 2015, 280, 1–12.
  10. Tao, D.P. Recent Advances in Fundamentals and Applications of Nanobubble Enhanced Froth Flotation: A Review. Miner. Eng. 2022, 183, 107554.
  11. Ma, F.; Tao, D.; Tao, Y.; Liu, S. An Innovative Flake Graphite Upgrading Process Based on HPGR, Stirred Grinding Mill, and Nanobubble Column Flotation. Int. J. Min. Sci. Technol. 2021, 31, 1063–1074.
  12. Hampton, M.A.; Nguyen, A.V. Nanobubbles and the Nanobubble Bridging Capillary Force. Adv. Colloid Interface Sci. 2010, 154, 30–55.
  13. Ishida, N.; Inoue, T.; Miyahara, M.; Higashitani, K. Nanobubbles on a Hydrophobic Surface in Water Observed by Tapping-Mode Atomic Force Microscopy. Langmuir 2000, 16, 6376–6380.
  14. Borkent, B.M.; Beer, S.D.; Mugele, F.; Lohse, D. On the Shape of Surface Nanobubbles. Langmuir 2010, 26, 260–268.
  15. Song, B.; Walczyk, W.; Schönherr, H.; Vandamme, T.F. Contact Angles of Surface Nanobubbles on Mixed Self-Assembled Monolayers with Systematically Varied Macroscopic Wettability by Atomic Force Microscopy. Langmuir 2011, 27, 8223–8232.
  16. Ma, F.; Tao, D.; Tao, Y. Effects of Nanobubbles in Column Flotation of Chinese Sub-Bituminous Coal. Int. J. Coal Prep. Util. 2022, 42, 1126–1142.
  17. Yan, S.; Fang, X.; Zhao, G.; Qiu, T.; Ding, K. Nanobubbles Adsorption and Its Role in Enhancing Fine Argentite Flotation. Molecules 2025, 30, 79.
  18. Oliveira, H.; Azevedo, A.; Rubio, J. Nanobubbles Generation in a High-Rate Hydrodynamic Cavitation Tube. Miner. Eng. 2018, 116, 32–34.
  19. Bu, X.; Zhang, T.; Chen, Y.; Peng, Y.; Xie, G.; Wu, E. Comparison of Mechanical Flotation Cell and Cyclonic Microbubble Flotation Column in Terms of Separation Performance for Fine Graphite. Physicochem. Probl. Miner. Process. 2018, 54, 732–740.
  20. Zhou, W.; Wu, C.; Lv, H.; Zhao, B.; Liu, K.; Ou, L. Nanobubbles Heterogeneous Nucleation Induced by Temperature Rise and Its Influence on Minerals Flotation. Appl. Surf. Sci. 2020, 508, 145282.
  21. Ma, F.; Tao, D. A Study of Mechanisms of Nanobubble-Enhanced Flotation of Graphite. Nanomaterials 2022, 12, 3361.
  22. Rao, K.H. Advances in Flotation Technology. In Flotation Technology; Reddy, K.H., Ed.; Springer: Berlin, Germany, 2013; pp. 1–50.
  23. Schulze, H.J. Probability of Aggregate Attachment in Flotation. Miner. Eng. 1989, 2, 1–16.
  24. Bulatovic, S.M. Handbook of Flotation Reagents: Chemistry, Theory and Applications; Elsevier: Amsterdam, Netherlands, 2007; Volume 1–3.
  25. Usui, S. Heterocoagulation as a Tool for Understanding the Surface Properties of Minerals. J. Colloid Interface Sci. 1972, 39, 241–246.
  26. Iwasaki, I. Flotation of Fine Particles. In Flotation: Theory, Reagents and Ore Testing; Fuerstenau, M.C., Ed.; AIME: New York, USA, 1976; pp. 200–230.
  27. Lima, R.; Valado, J.; Peres, A.E.C. Reverse Cationic Flotation of Iron Ores: A Comprehensive Review of Reagent Systems and Industrial Performance. Miner. Eng. 2013, 50–51, 122–132.
  28. Forsmo, S.; Samskog, P.O.; Björkman, B. Mechanisms in Anionic Reverse Flotation of Magnetite Ores. Eng. 2008, 21, 952–960.
  29. Chen, G.; Ge, Y.; Yu, Y. Beneficiation of Low-Grade Hematite Ore via Anionic Reverse Flotation at Yuanjiacun Concentrator. Int. J. Miner. Metall. Mater. 2005, 12, 18–25.
  30. Song, S.; Yuan, Z.; Wei, X. Processing of Siderite-Bearing Iron Ore via Stepped Flotation at Donganshan Concentrator. Metall. Min. Process. 2015, 32, 112–120.
  31. Lima, R.; Peres, A.E.C.; Marques, A.P. Selective Flocculation in Desliming of Iron Ores: Mechanisms and Industrial Application. Miner. Eng. 2012, 27–28, 37–46.
  32. Wang, Q.; Zhou, W.; Yan, S.; Zhang, L. Mechanisms of Nanobubble-Enhanced Flotation of Galena from Pyrite. Int. J. Miner. Metall. Mater. 2024, 31, 1–15.
  33. Thella, S.P.; Mukherjee, A.K.; Srikakulapu, R. Desliming Studies in Reverse Flotation of Iron Ore: A Critical Review. Int. J. Miner. Process. 2012, 116, 82–89.
  34. Fuerstenau, D.W.; Gaudin, A.M.; Miaw, D.T. Effect of Slimes on Flotation of Iron Ore. Trans. AIME 1958, 210, 402–410.
  35. Forsmo, S.; Sammskog, P.O.; Björkman, B. Mineralogical and Chemical Characterization of Low-Grade Magnetite Ore from Malmberget, Sweden. Eng. 2006, 19, 1473–1481.
  36. Zhang, X.; Wang, Q.; Wu, Z.; Tao, D. An Experimental Study on Size Distribution and Zeta Potential of Bulk Cavitation Nanobubbles and the Consequent Effects on Oil Adsorption on Graphite. Colloid Surface A 2021, 611, 125794.
  37. Oliveira, H.; Azevedo, A.; Rubio, J. Hydrodynamic Cavitation as an Efficient Tool for Nanobubble Generation in Laboratory and Industrial Scales. In Proceedings of the XXIII International Mineral Processing Congress; Aydogan, S., Ed.; Istanbul, Turkey, 2018; pp. 45–62.
  38. Malvern Panalytical Ltd. Zetasizer Nano-ZS90 User Manual; Malvern: Worcestershire, UK, 2020.
  39. Song, B.; Walczyk, W.; Schönherr, H. Contact Angles of Surface Nanobubbles: A Comparative Atomic Force Microscopy Study. Langmuir 2011, 27, 8223–8232.
  40. Zhou, W.; Chen, H.; Ou, L.; Shi, Q. Aggregation of Ultra-Fine Scheelite Particles Induced by Hydrodynamic Cavitation. Int. J. Miner. Process. 2016, 157, 236–240.
  41. Hernandez, C.; Nieves, L.; Leon, A.C.; Advincula, R.; Exner, A.A. Role of Surface Tension in Gas Nanobubble Stability Under Ultrasound. ACS Appl. Mater. Interfaces 2018, 10, 9949–9956.
  42. Bu, X.; Zhang, T.; Peng, Y.; Xie, G.; Wu, E. Multi-Stage Flotation for the Removal of Ash from Fine Graphite Using Mechanical and Centrifugal Forces. Minerals 2018, 8, 1–15.
  43. Liu, Y.; Wang, J.; Zhang, X.; Wang, W. Contact Line Pinning and the Relationship Between Nanobubbles and Substrates. J. Chem. Phys. 2014, 140, 054705.
  44. Zhang, X.; Chan, D.; Wang, D.; Maeda, N. Stability of Interfacial Nanobubbles. Langmuir 2013, 29, 1017–1023.
  45. Stockelhuber, K.W.; Radoev, B.; Wenger, A.; Schulze, H.J. Rupture of Wetting Films Caused by Nanobubbles. Langmuir 2004, 20, 164–168.
  46. Finch, J.A.; Nesset, J.E.; Acuña, C. Role of Frother on Bubble Production and Behaviour in Flotation. Eng. 2008, 21, 949–957.
  47. Sobhy, A.; Tao, D. Nanobubble Column Flotation of Fine Coal Particles and Associated Fundamentals. Int. J. Miner. Process. 2013, 124, 109–116.
  48. Ma, F.; Tao, D.; Tao, Y. Study on Nanobubble-Enhanced Flotation of Ultra-Fine Minerals. In Proceedings of the 52nd Conference of Metallurgists; Peppley, B., Ed.; Quebec, Canada, 2013; pp. 234–245.
  49. Fan, M.; Tao, D.; Honaker, R.; Luo, Z. Nanobubble Generation and Its Applications in Froth Flotation Part IV: Mechanical Cells and Specially Designed Column Flotation of Coal. Min. Sci. Technol. 2010, 20, 641–671.
  50. Tao, D.P.; Wu, Z.X.; Sobhy, A. Investigation of Nanobubble Enhanced Reverse Anionic Flotation of Hematite Ore. In Proceedings of the Mineral Processing Technologies; Mehrotra, S., Ed.; Springer: Berlin, Germany, 2023; pp. 156–172.
  51. Calgaroto, S.; Azevedo, A.; Rubio, J. Flotation of Quartz Particles Assisted by Nanobubbles. Int. J. Miner. Process. 2015, 137, 64–70.
  52. Etchepare, R.; Oliveira, H.; Nicknig, M.; Azevedo, A.; Rubio, J. Nanobubbles Generation using a Multiphase Pump: Properties and Features in Flotation. Miner. Eng. 2017, 112, 19–26.
  53. Zhang, X.; Gu, X.; Han, Y.; Parra-Álvarez, N.; Claremboux, V.; Kawatra, S.K. Stepped Flotation for Treatment of Carbonate-Rich Iron Ores: An Emerging Technology for Difficult Ore Beneficiation. Eng. 2023, 196, 107–125.
  54. Dobby, G.S. Flotation Column Design and Operational Considerations. In Flotation Science and Engineering; Meadows, R., Ed.; Marcel Dekker: New York, USA, 2002; pp. 340–390.
Regular Issue Subscription Review Article
Volume 03
Issue 01
Received 27/12/2025
Accepted 20/01/2026
Published 31/01/2026
Publication Time 35 Days
9

Login


My IP

PlumX Metrics