Cationic flotation of fine hematite using dodecyltrimethylammonium bromide (DTAB)

The flotation of -10 μm diameter hematite particles using dodecyltrimethylammonium bromide (DTAB) was carried out. The adsorption density of dodecyltrimethylammonium ions (DTA+) and the zeta potential were also measured in order to analyze the flotation results. The results are summarized as follows: (1) the hematite recovery of more than 90% is achieved at 2 - 3% surface coverage (θ) of DTA+ at pH 7.4 and 10. No steady flotation is obtained at pH 5 in spite of the fact that DTA+ adsorption takes place, (2) the adsorption density of DTA+ increases linearly with DTAB equilibrium concentration at various pH values (pH 5- 11). This behavior is similar to that of the quartz-DTAB system at low pH values (pH 5 - 7.4), and (3) the free energy change of the specific adsorption, ΔGsp, of DTA+ on hematite, calculated at isoelectric points, was found to be -4.4 - -4.7 kcal/mol in the pH range of 7.4 - 10. The relation between ΔGsp and θ of DTA+ for hematite is similar to that for quartz: ΔGsp tends to increase when θ exceeds 10%.