Using oxalic acid to eliminate the slime coatings of serpentine in pyrite flotation

The flotation of sulphide ore in the presence of fine serpentine has been always a problem due to "slime coatings". To solve this problem, attempts were made for the first time to eliminate the slime coatings of serpentine in pyrite flotation using oxalic acid (OA) as the selective depressant. Micro-flotation test results indicated the pyrite could be well floated in the presence of serpentine by addition of oxalic acid. Based on a series of measurements, including collector adsorption studies, zeta potential measurements, XPS analyses and turbidity tests, it was found that after conditioning with OA, serpentine carried negative charge which was similar to pyrite, inducing repulsion forces between pyrite and serpentine. In this way, the slime coatings of serpentine on pyrite surface were eliminated and the flotation performance of pyrite was restored under the action of OA. All in all, OA can be potentially applied as the depressant to improve flotation performance of sulphide ore associated with serpentine.