Influence of different concentrations of ionic solutions on coal spontaneous combustion

ABSTRACT

Considering the high cost of ionic liquids, this paper proposed to dilute ionic liquids with purified water to suppress coal spontaneous combustion based on an in-depth study on the mechanism of ionic liquids for suppressing coal spontaneous combustion. Three kinds of ionic liquids, namely, [HOEMIm][BF₄] (HOE), [BMIm][BF₄] (BM), and [AMIm]Cl (AM), were mixed with purified water to form ionic solutions with different concentrations. The differences in gas products of raw coal and samples treated with ionic solutions were comparatively analyzed, and then their mechanism of inhibiting coal spontaneous combustion was studied by calculating inhibition rates and apparent activation energy of samples. Furthermore, the molecular structure of coal was further studied by means of Fourier transform infrared spectroscopy. The results show that ionic solutions can not only absorb heat through water evaporation, but also reduce the alkyl chain content of coal by inerting hydrogen bonds in coal. Among the three kinds of ionic solutions with different concentrations, AM with a mass ratio of 1:10 achieves the best inhibitory effect.

KEYWORDS:

• Coal spontaneous combustion
• Inhibitor
• Ionic solution
• Apparent activation energy
• FTIR

Additional information

Funding

This work was supported by the Fundamental Research Funds for the Central Universities (2017CXNL02), the Natural Science Foundation of China (Grant Nos. 51704282; 51404263;51504251), the National Natural Science Foundation of Jiangsu(Grant Nos. BK20160272; BK20140187) and the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD).