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Real Time Analysis on Evolved Gas Emissions during High-Temperature Spontaneous Combustion of H2O-NH4Ac Extracted Coal

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The primary goal of this study is to investigate the effect of inherent calcium on the release of gaseous products during the high-temperature spontaneous combustion of coal. The coal samples were sequentially extracted progressively with water (H 2 O), ammonium acetate (NH 4 OAc), and hydrochloric acid (HCl) solutions. The amount of Ca in various occurrence modes in coal samples was then evaluated using an inductively coupled plasma equipped atomic emission spectrometer (ICP-MS). The results showed that all of the tested coal samples contained NH 4 Ac-soluble Ca, HCl-soluble Ca, and H 2 O-soluble Ca. The FTIR of raw and residual coal after H 2 O and NH 4 OAc extraction indicates that H 2 O and NH 4 OAc extraction would remove some carboxylate from the coal structure. The high-temperature spontaneous combustion of raw coal and residual coal after H 2 O and NH 4 OAc extraction was investigated by mass spectrometry and thermogravimetric analysis. H 2 O and NH 4 OAc extraction resulted in lower initial decomposition and ignition temperature, and no CO 2 was generated during the spontaneous combustion of H 2 O and NH 4 OAc-treated coal samples at temperatures below 400 °C. Significant CO 2 production was only observed at temperatures above 400 °C. The H 2 O-soluble calcium and organically bounded calcium in coal could alter the thermal evolution process of the coal structure, promoting the cracking of aliphatic side chains and therefore increasing the yield of H 2, CH 4, CO, and CO 2 . However, for coal with a relatively high H 2 O-soluble calcium content, water treatment transforms H 2 O-soluble calcium into Ca(OH) 2, which could accelerate the release of gaseous products during spontaneous combustion and increase the emission of H 2, CH 4, and CO. Finally, the mechanism for the effect of inherent calcium on the gaseous product generation was proposed.

Source: ACS Omega

DOI: 10.1021/acsomega.4c11508

Authors: Xiaoling Wang, Guolan Dou, Liying Zhang

Institutions: Jiangsu Vocational Institute of Architectural Technology, China University of Mining and Technology

Language: English

Topic: Coal Properties and Utilization

Subfield: Ocean Engineering

Field: Engineering

Domain: Physical Sciences

SDGs: Affordable and clean energy, Climate action

Open Access status: gold

Estimated APC paid: $1,935