ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Flotation features of fluorapatite with ricinoleic acid: the role of hydrogen bonds between collectors

Heng Zou, Qin-bo Cao, Dian-wen Liu, Xiu-min Chen, and Yong Jiao

Faculty of Land Resources Engineering, Kunming University of Science and Technology, Kunming, People’s Republic of China

E-mail: qinbocao@kust.edu.cn

Received: 18 August 2020  Accepted: 3 November 2020

Abstract:

Abstract

Improving the collecting ability of a collector is a crucial issue in phosphate flotation. In this work, ricinoleic acid (RA) was used as a collector for fluorapatite (FA, Ca₅(PO₄)₃F) flotation. There is an OH group in the middle of the RA molecule, and thus, hydrogen bonds (H-bonds) can be formed between RA species. The role of the H-bond between RA molecules in FA flotation was revealed by experimental and theoretical calculation methods. The flotation results suggested that RA was more efficient than oleic acid for FA flotation at pH 9. The RA⁻ anion was chemisorbed onto the negative FA surface, forming calcium ricinoleate (Ca(RA)₂) precipitates. The crystallization of Ca(RA)₂ on the FA surface was aided by the H-bonds between RA species. On the other hand, the results of quantum chemistry calculations showed that the H-bond in Ca(RA)₂ resulted in the close packing of RA⁻ anions. Such a packing structure may occur on the FA surface, which favors the formation of Ca(RA)₂ on the surface and FA flotation. Moreover, Ca(RA)₂ was more stable than calcium dioleate in solution, also contributing to the better flotation efficiency of RA. These theoretical calculation results clarified the beneficial effect of the H-bond between RA species on FA flotation at the atomic level.

Graphic abstract

Keywords: Flotation; Fluorapatite; Ricinoleic acid; Hydrogen bond

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-020-01417-6

Chemical Papers 75 (5) 1949–1958 (2021)