Chemical analysis of extracting transition metal oxides from polymetallic ore by sulphate processOtgon-Uul Enkh-Uyanga, Baatar Munkhtsetseg, Urtnasan Urangoo, Enkhtur Tserendulam and Davaadorj AgiimaaEPJ Web Conf., 140 (2017) 13004DOI: https://doi.org/10.1051/epjconf/201714013004