New Insights into the Depressive Mechanism of Sodium Silicate on Bastnaesite, Parisite, and Fluorite: Experimental and DFT Study

Jieliang Wang ^{1, 2, 3}

Wenda Lu ^{1, 2}

Cao Zhao ^{1, 2, 3}

Wu Xu ^{1, 2, 3}

Peng Wang ^{1, 2, 3}

Xiaoping Wang ^{1, 2, 3}

Wenli Liu ^{1, 4}

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School of Mining and Coal Engineering, Inner Mongolia University of Science and Technology, Baotou 014010, China |

Inner Mongolia Key Laboratory of Mining Engineering, Baotou 014010, China |

Key Laboratory of Green Extraction & Efficient Utilization of Light Rare-Earth Resources, Inner Mongolia University of Science and Technology, Ministry of Education, Baotou 014010, China |

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Baotou Steel Group Baoshan Mining Limited Corporation, Bayan Obo, Baotou 014080, China

Publication type: Journal Article

Publication date: 2024-08-27

MDPI

Journal: Minerals

scimago Q2

SJR: 0.495

CiteScore: 4.1

Impact factor: 2.2

ISSN: 2075163X

DOI: 10.3390/min14090870

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Abstract

The surface properties of bastnaesite and parisite are similar to their associated gangue mineral, fluorite, which makes the flotation separation of these two rare earth minerals from fluorite one of the industry’s most significant challenges. This study systematically investigates the inhibitory effects and mechanisms of sodium silicate (SS) on bastnaesite, parisite, and fluorite in an octyl hydroxamic acid (OHA) collector system through flotation experiments, various modern analytical methods, and DFT simulations. The flotation test results indicate that the inhibition effects of SS on the three minerals are in the order: fluorite > parisite > bastnaesite. Detection and analysis results indicate that SS forms hydrophilic complexes with Ca atoms on the surfaces of fluorite and parisite, enhancing surface hydrophilicity and inhibiting OHA adsorption, but its impact on bastnaesite is relatively minor. DFT simulation results show that OHA forms covalent bonds with metal ions on mineral surfaces, favoring five-membered hydroxamic-(O-O)-Ce/Ca complexes, and reacts more strongly with Ce atoms than Ca atoms. SS primarily forms covalent bonds with metal atoms on mineral surfaces via the SiO(OH)3− component, and OHA and SS compete for adsorption on the mineral surfaces. OHA has a stronger affinity for bastnaesite, whereas SS shows the highest affinity for fluorite, followed by parisite, and the weakest affinity for bastnaesite.