ABSTRACT The choice of depressant in magnesium-calcium separations is critical. This study was the first to use ethylene glycol diethyl ether diamine tetraacetic acid (EGTA) as a calcium chelator to regulate the flotation of magnesite and calcite in a sodium oleate system. The flotation test showed that the best separation effect of magnesite and calcite was achieved under the conditions of sodium oleate dosage of 100 mg/L, EGTA dosage of 200 mg/L, pH 11.0, and rotational speed of 1800 rpm. The contact angle test showed that the hydrophilicity of calcite increased with the addition of EGTA in the sodium oleate system, while the hydrophobicity of magnesite remained almost constant. The zeta potential showed that the addition of EGTA to the sodium oleate system changed the surface potential of calcite about 6 times that of magnesite, suggesting that EGTA is selectively adsorbed on the surface of calcite. Fourier transform infrared spectroscopy (FTIR) showed that the addition of EGTA under the sodium oleate system produced EGTA-specific peaks on the surface of calcite, while magnesite remained unchanged. X-ray photoelectron spectroscopy (XPS) results showed that the binding energy displacement of the calcite Ca2p peak was 40 times higher than that of the magnesite Mg1s peak.
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