Construction of Molecular Model and Adsorption of Collectors on Bulianta Coal.

Wenli Liu,He Zhang,Qiming Zhuo,Peng Xi

doi:10.3390/molecules25174030

Abstract

To study the effects of different oxygen functional groups on the quality of flotation clean low-rank coal, two kinds of collectors with different oxygen-containing functional groups, methyl laurate, and dodecanol, were selected and their flotation behaviors were investigated. The Bulianta coal was the typical sub-bituminous coal in China, and the coal molecular model of which was constructed based on proximate analysis, ultimate analysis, 13C-NMR, and XPS. The chemical structure model of the coal molecule was optimized, and the periodic boundary condition was added via the method of molecular dynamics methods. The different combined systems formed by collectors, water, and a model surface of Bulianta coal have been studied using molecular dynamics simulation. The simulation results of dodecanol and methyl laurate on the surface of Bulianta coal show that dodecanol molecules are not evenly adsorbed on the surface of coal, and have higher adsorption capacity near carboxyl and hydroxyl groups, but less adsorption capacity near carbonyl and ether bonds. Methyl laurate can completely cover the oxygen-containing functional groups on the coal surface. Compared with dodecanol, methyl laurate can effectively improve the hydrophobicity of the Bulianta coal surface, which is consistent with the results of the XPS test and the flotation test.

Highlights

Low rank coal, such as lignite and sub-bituminous coal, makes up more than 50% of the world’s proven coal deposits [1]
This result may be due to the existence first decreases with the increase of collector content
According to the relevant structural parameters obtained from the experiment, Bulianta coal molecular model is established, and the structure is optimized

Summary

Introduction

Low rank coal, such as lignite and sub-bituminous coal, makes up more than 50% of the world’s proven coal deposits [1]. With the increase of the world’s energy demand, the utilization of low-rank coal has become an urgent need and received widely attention [2]. The upgrading of low-rank coal to obtain high-quality coal resources has been conducted by the froth flotation method. This is a surface-based method based on the differences in surface properties between the target minerals and gangue minerals. In the process of froth flotation, the target minerals are often selectively hydrophobic by adding agents called collectors at the liquid/solid interface. The surface of low-rank coal is abundant with oxygen-containing functional groups (hydroxyl, carboxyl, carbonyl, phenolic hydroxyl), which will form a hydrogen bond with water molecules and lead to the low hydrophobicity of the coal surface [6].

Objectives

Methods

Results

Conclusion