THE ROLE OF SURFACTANT/POLYMER INTERACTIONS WITH THE SOLID-LIQUID INTERFACE IN FINE PARTICLE FLOTATION (POLYACRYLAMIDE)

Fine-sized (less than 10 microns) mineral particles occur in mineral processing because of inefficiencies in comminution and when low-grade ore bodies, which contain finely disseminated minerals, are processed. These fine particles present technological problems in the processing and separation stages for recovery of valuable mineral resources. The present investigation is concerned with a technique for separating fine mineral particles. The technique involves the use of flotation to remove aggregates formed by flocculation with a polymer and then made hydrophobic by addition of a collector.; The role of surfactant and polymer interaction with the solid-liquid interface was examined by measuring surfactant adsorption isotherms for sodium dodecylsulfonate on hematite at pH 4 in the absence and presence of pre-adsorbed polymers. The presence of an anionic polymer (polyacrylic acid) was found to significantly reduce the adsorption of surfactant. Surfactant adsorption in the presence of pre-adsorbed nonionic polymer (polyacrylamide) was affected to a lesser extent. In the anionic polymer-anionic surfactant system, electrokinetic potentials were found to increase in negative value with increasing amounts of pre-adsorbed polymer and to be partially responsible for reduced surfactant adsorption.; Flotation and contact angle measurements were used as an indication of hydrophobicity. Although different surfactant adsorption densities on hematite were observed for the pre-adsorbed nonionic and anionic polymer systems, the flotation behavior was similar. The amount of polymer used in the flocculation stage strongly influenced the flotation of the aggregated particles. Flotation was found to be depressed when polymer additions sufficient for surface saturation were used.; The separation of polyacrylic-acid flocculated hematite aggregates from unflocculated quartz particles was achieved by flotation with sodium dodecylsulfonate. Subsequent cleaning of the concentration by additional flotation stages yielded a higher grade product at some expense to the overall recovery.