Flocculation of hematite fines by anionic polyacrylamide polymers

: Flocculation studies on iron-ore fines (size < 10 mum) were conducted using three anionic polyacrylamide polymers over the pH range 4.0 - 10.0 and flocculant dosages up to 0.20 kg/ton. The flocculation was favourable under acidic conditions and was helped substantially by CaCl2 additions in alkaline conditions. Zeta potential measurements indicated a specific adsorption of polymers. Adsorption studies on the system indicated a pseudo-Langmuir type isotherm. Specific free energy of adsorption was estimated to be -26 to -34 kJ/mole for the three flocculants. Hydrogen bonding and electrostatic forces mainly appeared to influence flocculation in the system studied. Selective flocculation of iron-ore-silica fines mixtures was favourable with the above polymers, with the help of sodium silicate.