Coal gangue is a by-product in the process of coal production.If it is disposed, it will become a public hazard, not only occupying precious land but also destroying ecological environment.

• 煤矸石是煤炭生产过程中的副产品,如果弃之不用,就会成为一大公害,不仅占用宝贵的土地资源,而且污染和破坏生态环境。