ortho-bituminous coal

例句：

1. 1. The coal mine is located in the northwest of China.
   煤矿位于中国西北部。
2. 2. Coal is a major source of energy for many industries.
   煤炭是许多工业的主要能源来源。
3. 3. The coal industry has been facing challenges due to environmental regulations.
   由于环境法规，煤炭行业面临挑战。