Venturi Flotation Column Design for Selective Recovery of Pb and Zn from Fe Using Corn Starch under Controlled pH Conditions

Froth flotation is a key technique for the selective beneficiation of sulfide ores, particularly in separating galena (PbS) and sphalerite (ZnS) from pyrite (FeS2). However, conventional depressants such as sodium cyanide pose environmental and safety concerns. In this study, we investigated the use of corn starch as a biodegradable depressant in combination with an improved-designed Venturi-type flotation column to enhance the selective separation of lead and zinc from pyrite. A synthetic mixture of a raw material was prepared for flotation experiments under varying pH conditions (4, 7, and 10) and corn starch concentrations (0, 12.5, and 25 ppm). The Venturi column was optimized using computational fluid dynamics simulations and experimental trials, with the optimal air flow rate identified as 5 L/min for generating stable bubbles and enhancing bubble–particle interactions. Results showed that corn starch selectively depressed pyrite without significantly affecting galena floatability, particularly under alkaline conditions. The highest selectivity, indicated by a 43.62% Pb–Fe recovery gap, was achieved at pH 10 with 12.5 ppm starch. Sphalerite exhibited moderate sensitivity to starch dosage, with the best Zn–Fe separation observed at pH 4. XRF and XRD analyses confirmed the effective mineral separation, and the Pourbaix diagrams explained the electrochemical basis of the observed trends. This approach provides a sustainable and efficient alternative to conventional flotation.

Corn starch; Flotation; Galena; Pyrite; Sphalerite

Ahmadi, M., Gharabaghi, M., & Abdollahi, H. (2018). Effects of type and dosages of organic depressants on pyrite floatability in microflotation system. Advanced Powder Technology, 29(12), 3155–3162. https://doi.org/10.1016/j.apt.2018.08.015

Asimi-Neisiani, A., Saneie, R., Mohammadzadeh, A., Wonyen, D. G., & Chehreh Chelgani, S. (2023). Polysaccharides-based pyrite depressants for green flotation separation: An overview. International Journal of Mining Science and Technology, 33(10), 1229–1241. https://doi.org/10.1016/j.ijmst.2023.09.002

Chandra, A. P., & Gerson, A. R. (2009). A review of the fundamental studies of the copper activation mechanisms for selective flotation of the sulfide minerals, sphalerite and pyrite. Advances in Colloid and Interface Science, 145(1–2), 97–110. https://doi.org/10.1016/j.cis.2008.09.001

Chen, J. (2021). The interaction of flotation reagents with metal ions in mineral surfaces: A perspective from coordination chemistry. Minerals Engineering, 171. https://doi.org/10.1016/j.mineng.2021.107067

Chimonyo, W., Fletcher, B., & Peng, Y. (2020). Starch chemical modification for selective flotation of copper sulphide minerals from carbonaceous material: A critical review. Minerals Engineering, 156. https://doi.org/10.1016/j.mineng.2020.106522

Han, G., Wen, S., Wang, H., & Feng, Q. (2019). Effect of starch on surface properties of pyrite and chalcopyrite and its response to flotation separation at low alkalinity. Minerals Engineering, 143. https://doi.org/10.1016/j.mineng.2019.106015

Khoso, S. A., Hu, Y., Tian, M., Gao, Z., & Sun, W. (2021). Evaluation of green synthetic depressants for sulfide flotation: Synthesis, characterization and floatation performance to pyrite and chalcopyrite. Separation and Purification Technology, 259. https://doi.org/10.1016/j.seppur.2020.118138

Li, M. (2022). Fundamental understanding on the inception of hydrodynamic cavitation and its generated microbubbles in fine particle flotation.

Li, M., Bussion`ere, A., Bronson, M., Xu, Z., & Liu, Q. (2018). Study of Venturi tube geometry on the hydrodynamic cavitation for the generation of microbubbles [(in press)]. Minerals Engineering.

Mkhonto, P. P., Zhang, X., McFadzean, B., Taguta, J., Zhu, Y., Han, L., & Ngoepe, P. E. (2024). Incorporating pH into DFT-D+U and microflotation recovery studies on heterocyclic collector-pyrite interactions. Separation and Purification Technology, 337. https://doi.org/10.1016/j.seppur.2024.126430

Mu, Y., Peng, Y., & Lauten, R. A. (2015). Electrochemistry aspects of pyrite in the presence of potassium amyl xanthate and a lignosulfonate-based biopolymer depressant. Electrochimica Acta, 174(1), 133–142. https://doi.org/10.1016/j.electacta.2015.05.150

Mu, Y., Peng, Y., & Lauten, R. A. (2016). The depression of pyrite in selective flotation by different reagent systems—A literature review. Minerals Engineering, 96–97, 143–156. https://doi.org/10.1016/j.mineng.2016.06.018

Murphy, R., & Strongin, D. R. (2009). Surface reactivity of pyrite and related sulfides. Surface Science Reports, 64(1), 1–45. https://doi.org/10.1016/j.surfrep.2008.09.002

Nagaraj, D. R., & Farinato, R. S. (2016). Evolution of flotation chemistry and chemicals: A century of innovations and the lingering challenges. Minerals Engineering, 96–97, 2–14. https://doi.org/10.1016/j.mineng.2016.06.019

Nayak, A., Jena, M. S., & Mandre, N. R. (2022). Beneficiation of Lead-Zinc ores—a review. Mineral Processing and Extractive Metallurgy Review, 43(5), 564–583. https://doi.org/10.1080/08827508.2021.1903459

Peleka, E. N., Gallios, G. P., & Matis, K. A. (2017). A perspective on flotation: A review. Journal of Chemical Technology and Biotechnology, 93(3), 615–623.

Prameswara, G., Trisnawati, I., Handini, T., Poernomo, H., Mulyono, P., Prasetya, A., & Petrus, H. T. M. B. (2023). Recovery of critical elements (dysprosium and ytterbium) from alkaline process of indonesian zircon tailings: Selective leaching and kinetics study. International Journal of Technology, 14(4), 770–779. https://doi.org/10.14716/ijtech.v14i4.4960

Protopopoff, E., & Marcus, P. (2003). Potential-pH diagrams for sulfur and hydroxyl adsorbed on copper surfaces in water containing sulfides, sulfites or thiosulfates [(in press)]. Corrosion Science. www.elsevier.com/locate/corsci

Qin, W., Wei, Q., Jiao, F., Yang, C., Liu, R., Wang, P., & Ke, L. (2013). Utilization of polysaccharides as depressants for the flotation separation of copper/lead concentrate. International Journal of Mining Science and Technology, 23(2), 179–186. https://doi.org/10.1016/j.ijmst.2013.04.022

Ran, J., Li, Y., Zhao, X., Jiang, M., & Gao, E. (2023). Utilization of soluble starch as the depressant to flotation separation of pyrite from arsenopyrite. Separation and Purification Technology, 310. https://doi.org/10.1016/j.seppur.2023.123155

Sakamatapan, K., Mesgarpour, M., Mahian, O., Ahn, H. S., & Wongwises, S. (2021). Experimental investigation of the microbubble generation using a venturi-type bubble generator. Case Studies in Thermal Engineering, 27. https://doi.org/10.1016/j.csite.2021.101238

Tjhia, M. A., Yahya, M. N. F., & Ulum, R. M. (2024). Characteristics of treated monazite in different particle sizes to upgrade the rare earth elements content by using mechanochemical and roasting processes. International Journal of Technology, 15(2), 463–471.

Trisnawati, I., Prameswara, G., Mulyono, P., Prasetya, A., & Petrus, H. T. B. M. (2020). Sulfuric acid leaching of heavy rare earth elements (HREEs) from indonesian zircon tailing. International Journal of Technology, 11(4), 804–816. https://doi.org/10.14716/ijtech.v11i4.4037

Wang, D., & Liu, Q. (2021). Hydrodynamics of froth flotation and its effects on fine and ultrafine mineral particle flotation: A literature review. Minerals Engineering, 173. https://doi.org/10.1016/j.mineng.2021.107220

Wang, Y. (2002). Preparation of nanocrystalline metal oxide powders with the surfactant-mediated method. Inorganic Chemistry Communications, 5, 751–755.

Wei, B., Mao, Y., Wang, L., Shen, P., Wang, H., & Liu, D. (2024). Sources, performance and mechanisms of metal ions in the flotation process of copper, lead, and zinc ores: A review. Minerals, 14(11). https://doi.org/10.3390/min14111105

Wills, B. A., & Finch, J. A. (2016). Wills’ mineral processing technology: An introduction to the practical aspects of ore treatment and mineral recovery (8th ed.). Elsevier Science; Technology Books.

Xiong, Y., & Peng, F. (2015). Optimization of cavitation venturi tube design for pico and nano bubbles generation. International Journal of Mining Science and Technology, 25(4), 523–529. https://doi.org/10.1016/j.ijmst.2015.05.002

Yang, B., Zhu, H., Zeng, L., Feng, J., & Luo, H. (2021). An environmental-friendly sphalerite depressant (2-hydroxyphosphonoacetic acid) for the selective flotation separation of sphalerite from galena. Journal of Molecular Liquids, 343. https://doi.org/10.1016/j.molliq.2021.117614

Zhai, Q., Hu, Y., Liu, R., & Sun, W. (2024). Investigation of pullulan polysaccharide as a sphalerite depressant for chalcopyrite separation: Flotation behavior and interfacial adsorption mechanism. Advanced Powder Technology, 35(10). https://doi.org/10.1016/j.apt.2024.104621

Zhao, L., Li, K., Matkarimov, S. T., Liu, C., Bao, S., & Yang, S. (2025). Mechanical activation improves green depressant starch for the flotation separation of pyrite from chalcopyrite via molecular structure optimization. Journal of Molecular Liquids, 424. https://doi.org/10.1016/j.molliq.2025.127122

Zhou, S., Wang, X., Bu, X., Wang,M., An, B., Shao, H., Ni, C., Peng, Y., & Xie, G. (2020). A novel flotation technique combining carrier flotation and cavitation bubbles to enhance separation efficiency of ultra-fine particles. Ultrasonics Sonochemistry, 64. https://doi.org/10.1016/j.ultsonch.2020.105005

Zhou, Y., Cui, J., Chen, Z., Liu, J., He, L., Fan, W., & Huo, M. (2025). Parametric analysis of venturi-type microbubble generator and the bubble fragmentation dynamics. Desalination and Water Treatment, 322. https://doi.org/10.1016/j.dwt.2025.101116