WETTABILITY OF CASSITERITE IN PRESENCE OF SODIUM DODECYL-SULFATE

Measurements were made of contact angles for water, glycerol, formamid e, diiodomethane and bromoform on the cassiterite surface covered with a sodium dodecyl sulphate (SDS) film formed by the immersion of cassi terite plates in aqueous SDS solutions at a fixed concentration (5 10( -5) M) but different pH (from 1.98 to 9.56). From these data, the disp ersion and nondispersion (or Lifshitz-van der Waals and acid-base) com ponents of the surface free energy of the cassiterite/SDS film were de termined. Also, the electron-acceptor and electron-donor parts of the acid-base component were evaluated. The measurements and calculations shown that the wettability of cassiterite covered with an SDS film dep ends on both the pH and the method of preparation of the cassiterite s amples before the adsorption of SDS. It was also found that the most s uitable condition for flotation processes should be attained at pH 2.8 5, at which the contact angles for polar liquids were greatest and the value of the nondispersion or acid-base component of the cassiterite/ SDS film surface free energy was smallest.