1. Energy pillar industry: Coal industry is the energy pillar industry of a country or region, which is very important for economic development and energy security.

2. Energy Treasure: Coal is called energy treasure because it is a rich mineral resource with great energy potential and value.

3. Energy cornerstone: Coal industry is described as the cornerstone of energy, because it plays an important role in energy supply and energy structure and has an important impact on the economic stability and development of a country or region.