Wetting of cassiterite by sodium dodecyl sulphate solutions

Abstract

The contact angles for water and SDS solutions with concentrations from 5 x I0 -6 to 5 x10 -2 M at different pH values, on cassiterite plates treated and not treated by acids before experiments were measured as a function of the time of contact between the droplet of solution and the cassiterite surface. The contact angle was also measured for SDS solutions on cassiterite coated with an SDS film. The results obtained were compared with those calculated on the basis of Young's equation. Good agreement between the calculated and the measured contact angles was found for a given system. It was also found that dry cassiterite possesses a very hydrophobic surface but that it can be hydrated along the time of contact with the SDS solution droplet. The wettability of cassiterite with a hydrated surface depends on the concentration and pH of the SDS solution. The lowest wettability is observed for solutions at concentrations between 5xl0 -5 and 10 -4 M at pH 2.85, which are the most suitable conditions for the flotation of cassiterite.