The separation of magnesite from dolomite using flotation is difficult owing to their similar crystal structure, chemical and surface composition, and dispulp characteristics. In this study, in the flotation system with sodium oleate (NaOL) as the collector, to improve the flotation separation efficiency, the differential floatability between both the minerals was increased using ethylenediamine-N.N'-bis(2-hydroxyphenylacetic acid) (EDDHA). The results demonstrated that the selectivity of EDDHA for both minerals was high at a pH of 11.0 using 50 mg/L of EDDHA and 120 mg/L of NaOL. The recoveries of magnesite and dolomite were 92.07% and 10.82%, respectively. To observe the adsorption of EDDHA on the surfaces of the minerals and investigate its flotation mechanism, zeta potential, contact angle, ultraviolet spectrophotometry, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy measurements were conducted. The pH adjustments in two stages in the flotation system enhanced the selectivity of EDDHA. (C) 2019 Elsevier B.V. All rights reserved.