Exploring Dextrin as an Eco-Friendly Depressant for Selective Flotation Separation of Scheelite and Calcite Minerals

ABSTRACTDepressants are essential additives in the flotation separation of scheelite-calcite minerals. However, traditional inorganic depressants such as sodium silicate have the disadvantages of high dosage, environmental pollution, and being non-efficient, which leads to a growing interest in eco-friendly and effective organic alternatives. In this study, a polysaccharide, dextrin, was used as a green depressant for the flotation separation of scheelite from calcite. Micro-flotation experiments indicated that dextrin selectively depressed calcite at natural pH yet scheelite remained floatable using sodium oleate (NaOL) as a collector. Adsorption density and zeta potential results indicated that dextrin was preferentially adsorbed on the calcite surface and prevented the subsequent NaOL from adsorption. By contrast, dextrin had a weak interaction with scheelite, allowing NaOL to be adsorbed on the scheelite surface. Fourier transform infrared spectroscopy (FTIR) analysis and density functional theory (DFT) calculations suggested that the Ca2+ active sites on the calcite surface interacted with -OH groups on the carbon ring of dextrin. X-ray photoelectron spectroscopy (XPS) tests confirmed the chemical interaction between -OH groups in dextrin and Ca2+ active sites on the mineral surfaces, and importantly, the interaction was much stronger for calcite than for scheelite.KEYWORDS: Dextrindepressantgreen chemicalflotation separationscheelitecalcite Credit authorship contribution statementWei Yao and Yue Wu: Conceptualization, Methodology, Data curation, Formal analysis, Investigation, Writing – original draft. Maolin Li, Rui Cui, and Ming Zhang: Conceptualization, Project administration. Jiaying Li, Zhehui Yang, Yingying Fu, and Zhiqin Pan: Formal analysis. Daowei Wang: Formal analysis, Writing – review & editing.AcknowledgmentsThe authors would like to thank the National Natural Science Foundation of China (Project No. 51704214 & 51704215) and “the 14th Five Year Plan” Hubei Provincial advantaged characteristic disciplines (groups) project of Wuhan University of Science and Technology (2023A0401) for support. The authors would also thank the Shiyanjia Lab (www.shiyanjia.com) for the XRD and XPS tests and thank Prof. Qi Liu at the University of Alberta for offering the modified Hallimond tube for flotation.Additional informationFundingThe work was supported by the National Natural Science Foundation of China [51704214]; “the 14th Five Year Plan” Hubei Provincial advantaged characteristic disciplines (groups) project of Wuhan University of Science and Technology [2023A0401].