Enhanced flotation of hemimorphite: Adjusting mineral surface potential with sodium thiocyanate as activator

•1. Sodium thiocyanate used as activator in flotation process for the first time.•2. Sodium thiocyanate has a better activation effect on heteromorphite than that of sodium sulfide.•3. The ambidentate ligand SCN- can chemisorbed on the heteromorphite surface via S or N elements.•4. After Sodium thiocyanate treatment, zeta potential of the heteromorphite was greatly decreased.•5. Sodium thiocyanate can enhance the physical adsorption strength of collector ODA on the mineral surface.