A review of various mineral processing technologies and their application to the removal of sulphides from mill tailings has been completed for the partners of the MEND consortium. The project included a descriptive review as well as bench scale testing of several processing methods.

Five mill tailings samples were obtained from three operating mines including:

• Placer Dome – Detour Lake Mine
• Lac Minerals – La Mine Doyon
• Les Mines Selbaie – Blast 5180.020 North
• Les Mines Selbaie – Blast 5180.022 Center
• Les Mines Selbaie – Blast 5240.141

The quantity of sample from Les Mines Selbaie – Blast 5180.020 North was insufficient for testing purposes and was therefore rejected. The samples were processed by gravity and flotation separation processes to split the samples into sulphide and non-sulphide fractions. The separation processes tested included:

• Falcon Concentrator
• Knelson Concentrator
• Reichert Tray
• 1/8 Wilfley shaking table
• Carpco LC3000 spiral concentrator
• direct flotation with a variety of pre-processing steps and collectors.

The samples were characterized initially, processed with the above techniques and reanalyzed to determine the effectiveness of the sulphide separation. The characterizations included humidity cell tests and acid base accounting, ICP analysis and a mineralogical evaluation.

The results of the study proved that the gravity techniques tested were incapable of separating the sulphides sufficiently to remove the acid generating capability of the tailings. This is likely due to the fact that the sulphide fractions tend to be concentrated in the finest size fractions of the tailings. The separation technique tested that was successful in removing the acid generating potential of the tailings samples was direct flotation.