Biodegradable hematite depressants for green flotation separation – An overview

•Depressant plays an important role in the reverse flotation separation of iron ores.•Biodegradable reagents can be effectively used as depressants in reverse hematite flotation.•Polysaccharides and polyphenolics are promising green depressants for hematite.•H-bonding is the most common adsorption mechanism between iron and green depressants.