Water quality effects on bubble-particle attachment of pyrrhotite

Abstract

In froth flotation, separation between the valuable and the gangue minerals comes as a result of the attachment of hydrophobic particles to air bubbles. Considering the importance of bubble formation and bubble-particle attachment, it is evident that the pulp phase facilitates the events for the most crucial requirements of successful flotation. Water forms the bulk of the pulp phase; and as a result of water scarcities in countries like South Africa, the need to recycle process water within mining operations is increasing. Hence it is of great importance to understand the effects of water quality on the vital sub-processes within the flotation process, particularly bubble-particle attachment. A novel attachment timer which allows for 396 opportunities for bubble-particle attachment was used for the bubble-particle attachments tests in this work. Three water qualities of increasing ionic strength were tested both in the presence and absence of a xanthate collector to see the effect of increasing ionic strength of synthetic plant water on the bubble-particle attachment probability. The attachment time measurements showed a general decrease in attachment probability as the ionic strength of the synthetic plant water increased both in the absence and presence of a collector. This result indicated that increasing the concentration of the ions present in synthetic plant water lowered the probability of pyrrhotite particles attaching to air bubbles. Further, adsorption studies showed that less xanthate adsorbs on the mineral surface at the highest ionic strength of synthetic plant water under study. This indicates that increases in the ionic strength of synthetic plant water hindered the xanthate adsorption on the pyrrhotite surface. Furthermore, an increase in the zeta potential of pyrrhotite with increasing ionic strength was reported, indicating cation adsorption on the mineral surface. The study presented shows a direct relationship between the zeta potential and attachment probability.