Improving the methods for determining the promising boundaries of iron ore open pits Serhii Lutsenko, Yulian Hryhoriev, Volodymyr Peregudov, Aidar Kuttybayev and Asel Shampykova E3S Web Conf., 280 (2021) 01005 Published online: 30 June 2021 DOI: 10.1051/e3sconf/202128001005