Development and Performance Study of a New Physicochemical Composite Inhibitor for Coal Spontaneous Combustion Control

ABSTRACT

In order to restrain the spontaneous combustion of coal and ensure the safety of coal mine, an environment-friendly whole-process-inhibiting hydrogel-tea polyphenols-halloysite nanotubes (HNTs) physicochemical composite inhibitor was prepared. The optimal ratio was determined by response-surface experiment, namely, tea polyphenol 2.42%, neutralization degree 80%, initiator dosage 1.68%, crosslinking agent 1%, and crossing point temperature 159.74°C. Compared with pure hydrogel inhibitor and tea polyphenol hydrogel inhibitor, the composite inhibitor performed superior whole-process inhibition effect, with the lowest oxygen consumption rate, CO, and CO2 production rate. The overall inhibition rate was stable at approximately 55% and its highest value was 58%, which indicated that tea polyphenols and HNTs effectively improved the thermal stability. The radical concentration treated with composite inhibitor was the lowest with the reduction of 2.784 × 1017/g lower than that of raw lignite, which proved that the composite inhibitor improved the inhibiting effect microscopically. Finally, inhibition mechanisms of the composite inhibitor were proposed. The results of this work suggest that composite inhibitor is an effective inhibitor of coal oxidation.

KEYWORDS:

• Tea polyphenols
• halloysite nanotubes
• temperature-programmed experiment
• electron spin resonance (ESR)
• coal spontaneous combustion

Additional information

Funding

The authors appreciate the financial support of project numbers FRF-IC-20-01 and FRF-IC-19-013, provided by the Fundamental Research Funds for the Central Universities; project numbers [51974015], [51904292], and [51474017], provided by the National Natural Science Foundation of China; project number [2018YFC0810600], provided by the National Key Research and Development Program of China; number [2017CXNL02], provided by the Fundamental Research Funds for the Central Universities (China University of Mining and Technology); project number [BK20180655], provided by the Natural Science Foundation of Jiangsu Province; project number [WS2018B03], provided by the State Key Laboratory Cultivation Base for Gas Geology and Gas Control (Henan Polytechnic University); and project number [E21724], provided by the Work Safety Key Lab on Prevention and Control of Gas and Roof Disasters for Southern Coal Mines of China (Hunan University of Science and Technology).