Concept and Practice of Open-pit Mining Area Restoration and Reuse --- Taking an Open-pit Coal Mining Area in Datong, Shanxi as an ExampleHuang Jiayin, Hu Baoan, Tan Xiangjun, Cheng Jin and Li LongE3S Web Conf., 145 (2020) 02014DOI: https://doi.org/10.1051/e3sconf/202014502014