Effect of sodium silicate on the magnetic separation of ilmenite from titanaugite by magnetite selective coating

Surface magnetization provides a possible approach for recovering weak or non-magnetic minerals via magnetic separation. In the present study, magnetite selective coating was used to enlarge the magnetic difference between ilmenite and titanaugite and further separate them. During this process, the selective coating behavior of magnetite was investigated with sodium silicate depressant and sodium oleate surfactant on mineral surfaces. The SEM analysis and magnetic separation results revealed that magnetite displayed a selective coating behavior on the surface of ilmenite and titanaugite, resulting in a large recovery difference by approximately 53% between them. The results of zeta potential and adsorption measurements indicated that sodium silicate preferred to adsorb onto titanaugite surfaces and prevented sodium oleate adsorption but not on ilmenite. Contact angle analysis suggested that the selective adsorption of reagents led to the hydrophobic difference of minerals. EDLVO calculation results illustrated that hydrophobic attraction dominated the selective adhering behavior of magnetite on ilmenite and titanaugite. After magnetite coating, the magnetic separation recovery and TiO2 grade of artificial mixtures were increased by approximately 26.33% and 4.7%, respectively. [Display omitted] •Sodium silicate selective adsorption strengthened selectivity of magnetite coating.•Selective magnetite coating enlarged magnetic difference of ilmenite and titanaugite.•Adhering mechanism of magnetite to ilmenite and titanaugite was expounded by EDLVO.