FINE - COARSE PARTICLE INTERACTIONS AND AGGREGATION IN SPHALERITE FLOTATION

The behaviour of fine particles in the flotation separation of mineral s has become of rapidly increasing importance as new, fine grained dep osits are exploited. Fine particles float poorly and less-selectively under normal flotation conditions. The behaviour of fine (<20 mu m) an d coarse (38-75 mu m) sphalerite has been correlated between microflot ation and aggregation studies. This study utilises two novel technique s for obtaining direct evidence of particle interactions within a cond itioning pulp. On-line particle size distribution enables the onset of aggregation of fine particles under potation related conditions, duri ng addition of reagents, to be determined Concurrent evidence of parti cle interactions has been observed using optical microscopy. Significa nt aggregation to 20-30 mu m aggregates during agitation conditioning before reagents was observed. Fine particles exhibit poor flotation re sponse and some aggregation after Cu(II) activation alone. On addition of collector at tow pH, potation recovery and extent of aggregation ( >100 mu m) increased dramatically. In the presence of coarse particles at low pH, a high percentage of fine particles were recovered indicat ing a fine-coarse particle aggregation (''piggy-backing'') mechanism o ccurring during conditioning with Cu(II) alone. (C) 1997 Elsevier Scie nce Ltd.