Flotation separation of galena from sphalerite using hyaluronic acid (HA) as an environmental-friendly sphalerite depressant

•HA selectively depressed ZnS but barely influenced the flotation of PbS.•HA hindered the adsorption of SIBX due to the stronger affinity to ZnS.•HA was chemisorbed on ZnS through the bonding of carboxyl and N-acetyl with Zn.•HA was a nontoxic and eco-friendly alternative for traditional ZnS depressant.