Effectiveness evaluation for geothermal heat recovery in closed mines of Donbas Dmytro Rudakov, Oleksandr Inkin, Nataliia Dereviahina and Vadym Sotskov E3S Web Conf., 201 (2020) 01008 Published online: 23 October 2020 DOI: 10.1051/e3sconf/202020101008