Investigation of the effect of different distilled water, rainwater and seawater mass ratios on coal spontaneous combustion characteristics

Hao Liu; Zenghua Li; Yongliang Yang; Guodong Miao; Purui Li; Guoqin Wang

doi:10.1016/j.scitotenv.2023.165878

Investigation of the effect of different distilled water, rainwater and seawater mass ratios on coal spontaneous combustion characteristics

Sci Total Environ. 2023 Nov 20:900:165878. doi: 10.1016/j.scitotenv.2023.165878. Epub 2023 Jul 29.

Authors

Hao Liu¹, Zenghua Li², Yongliang Yang¹, Guodong Miao¹, Purui Li¹, Guoqin Wang¹

Affiliations

¹ School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China.
² School of Safety Engineering, China University of Mining and Technology, Xuzhou 221116, China; Key Laboratory of Gas and Fire Control for Coal Mines (China University of Mining and Technology), Ministry of Education, Xuzhou 221116, China. Electronic address: lzh6512@126.com.

PMID: 37524190
DOI: 10.1016/j.scitotenv.2023.165878

Abstract

When water comes into contact with coal, the risk of coal spontaneous combustion should be reassessed. In order to analyze the effect of distilled water, rainwater and seawater on the coal self-heating, thermogravimetric analysis (TGA) was applied to investigate the differences between the macroscopic oxidation properties of raw coal and water-immersed coal. The risk of coal spontaneous combustion increases after water immersion, but different types of water have different degrees of influence on the spontaneous combustion of coal. The microscopic pore structure and elemental changes on the surface of coal samples before and after water immersion were studied by Scanning Electron Microscope (SEM), low-pressure nitrogen gas adsorption (LP-N₂GA) and Energy Dispersive Spectroscopy (EDS) experiments. Fourier infrared spectroscopy (FTIR) was used to investigate the change of active groups. The results show that the pore structure of coal samples immersed in water is much more developed than that of raw coal. In the low-temperature oxidation stage, moisture evaporation consumes much oxidation heat and inhibits the coal self-heating. After the stage, it promotes the coal spontaneous combustion. The content of the hydroxyl group increases, and the content of carbonyl and carboxyl decreases. The alkali metal elements can act as catalysts and active carriers of oxygen, enhancing the oxidation activity of coal. The results are helpful to understand the mechanism of different distilled water, rainwater and seawater mass ratios on coal spontaneous combustion and avoid potential self-heating after immersion.

Keywords: Coal spontaneous combustion; Different water samples; Functional groups; LP-N(2)GA; SEM-EDS; TGA.