Means of protecting materials from spontaneous coal combustion: current developments, mechanisms, classifications, and prospects

Spontaneous coal combustion poses serious threats to the world and especially to China, the world's largest coal producer and user. Apart from spurring monetary losses in national exchequers and resource losses for countries, spontaneous coal combustion results in a loss of life, which cannot be measured based on costs. Innumerable researchers and scholars in China and abroad have paid considerable attention to studying means of protecting materials from spontaneous coal combustion. A variety of materials that prevent spontaneous coal combustion have been developed. The goal of this paper is reveal the academic literature on spontaneous coal combustion. In this comprehensive review, mechanisms of spontaneous coal combustion, research findings and advantages and shortcomings of materials that prevent spontaneous coal combustion are explored. In view of different coal mining conditions and material properties, materials that prevent spontaneous coal combustion are classified in accordance with material phases. The development of various coal fire extinguishing materials is discussed. Our comprehensive review can thus be used to prevent and control spontaneous coal combustion and to curtail the currently frequent disasters resulting from spontaneous coal combustion.