Dual-Ligand Hydroxamic Acid Collector: Performance and Mechanism in the Depressant-Free Flotation of Fluorite from Calcite.

Authors

Bangyi Zeng, Chen Cheng, Sayfidin Safarov, Alexander E Burdonov, Nadezhda V Vchislo, Fengping Xu, Wenfang Che, Xiaowen Yang, Jianping Peng, Hong Zhong, Xiangping Chen, Hongling Wang, Xin Ma, Jinpeng Ma, Zhiqiang Huang

Published in

Langmuir : the ACS journal of surfaces and colloids. Jul 27, 2026. Epub Jul 27, 2026.

Abstract

Because of the similar surface properties of fluorite and calcite, their separation remains quite challenging. In this study, a novel hydroxamic collector, phthaloyl hydroxamic acid (PHA), was synthesized and applied for the flotation separation of fluorite from calcite for the first time. Microflotation results demonstrated that, at pH 7 with 20 mg/L PHA, fluorite recovery reached 92.5%, while calcite recovery was only 15.5%. In contrast, sodium oleate (NaOL) exhibited poor selectivity under identical conditions, recovering both minerals at similar levels (82% for fluorite and 86% for calcite). Compared with benzohydroxamic acid (BHA), which required an elevated pH of 9 to achieve selective separation (91% fluorite vs 20% calcite), PHA delivered comparable or superior selectivity at a milder pH 7. Contact angle, FTIR, ζ-potential, and XPS analyses collectively confirmed the selective chemisorption of PHA onto fluorite surfaces via chelation between -CONHOH groups and surface Ca atoms. Adsorption experiments showed that the adsorption density of PHA on fluorite (0.045 mg/g) was approximately six times higher than that on calcite (0.007 mg/g). Density functional theory (DFT) calculations further revealed a substantially stronger adsorption energy on fluorite (-239.87 kJ/mol) than on calcite (-62.12 kJ/mol), with the optimized geometry confirming five-membered chelate ring formation. Collectively, PHA is a highly promising collector for the efficient and depressant-free flotation separation of fluorite from calcite.

PMID:
42504624
Bibliographic data and abstract were imported from PubMed on 27 Jul 2026.

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