Interaction and Inhibition Mechanism of Sulfuric Acid with Fluorapatite (001) Surface and Dolomite (104) Surface: Flotation Experiments and Molecular Dynamics Simulations

The natural wettability of apatite and dolomite and the effect of sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) and sodium oleate (NaOl) on the floatability and wettability of both minerals were studied using single-mineral flotation and contact angle measurement. The flotation...

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Bibliographic Details
Main Authors: Aoao Chen, Xuming Wang, Qin Zhang
Format: Article
Language:English
Published: MDPI AG 2023-12-01
Series:Minerals
Subjects:
Online Access:https://www.mdpi.com/2075-163X/13/12/1517
Description
Summary:The natural wettability of apatite and dolomite and the effect of sulfuric acid (H<sub>2</sub>SO<sub>4</sub>) and sodium oleate (NaOl) on the floatability and wettability of both minerals were studied using single-mineral flotation and contact angle measurement. The flotation experiments demonstrated that adding NaOl, apatite, and dolomite had good floatability. After adding H<sub>2</sub>SO<sub>4</sub>, the floatability of apatite decreased significantly. H<sub>2</sub>SO<sub>4</sub> effectively inhibits apatite flotation. Contact angle measurements show that the use of H<sub>2</sub>SO<sub>4</sub> induces a significant difference in surface wettability between apatite and dolomite. The moderate addition of H<sub>2</sub>SO<sub>4</sub> can increase the contact angle of dolomite. In order to study the selective inhibition mechanism of H<sub>2</sub>SO<sub>4</sub> in phosphorite flotation, molecular dynamics simulations (MDSs) were conducted to investigate the interaction between H<sub>2</sub>SO<sub>4</sub> and fluorapatite and dolomite at the atomic–molecular level. The results of MDSs reveal that H<sub>2</sub>SO<sub>4</sub> interacts with Ca sites on both fluorapatite and defective dolomite surfaces, hindering the interaction of NaOl with Ca sites on both mineral surfaces. SO<sub>4</sub><sup>2−</sup> ions cannot prevent the interaction of oleate ions with Mg sites on dolomite surface. It is worth mentioning that SO<sub>4</sub><sup>2−</sup> ions occupy the defective vacancies formed due to the dissolution of CO<sub>3</sub><sup>2−</sup> on the surface of dolomite and interact with Ca sites. The remaining H<sub>2</sub>SO<sub>4</sub> is subsequently adsorbed onto the surface of dolomite. Experimental and simulation results show that, due to the interaction of H<sub>2</sub>SO<sub>4</sub> and NaOl, the surface of apatite can still undergo hydration forming a water molecule layer and maintaining a macroscopic hydrophilic property. In contrast, the oleate ions form an adsorption layer on dolomite transitioning it from a hydrophilic to a hydrophobic state. During the phosphate flotation process, the addition of an appropriate amount of sulfuric acid can further diminish the hydration of the dolomite surface, so that the surface of dolomite is more hydrophobic.
ISSN:2075-163X