The role of cationic surfactants in the selective flotation of phosphate ore constituents

Abstract

The quaternary amine salts cetylrimethyl ammonium bromide (CTAB) and cetylpyridinium bromide (CPB), as well as the primary amine salts dodecylammonium acetate (DAA) and cetylammonium acetate (CAA), were used to determine the flotation characteristics of the major constituents of phosphate ores. The pure chemicals tricalcium phosphate (T.C.P.) and calcium carbonate and the pure minerals francolite, calcite and quartz were investigated. Adsorption of CTAB on francolite is limited to a very loose packed monolayer which is very similar to that on CaCO 3 but not T.C.P. The low affinity of francolite to CTAB and hence its lower floatability were interpreted in terms of the coexisting surface carbonate groups and surface roughness. Effective separation of T.C.P. from the CaCO 3 mixture is reached on using 0.2 mM CTAB solution. Quartz, on the other hand, is readily floated from synthetic ores by quaternary ammonium and primary ammonium salts, but the latter are less superior and their selectivity decreases with increasing chain length. Phosphates and carbonates float almost equally with DAA and CAA. The adsorption and flotation properties of three types of phosphate ores, namely (I) siliceous- , (II) siliceous—calcareous- , and (III) calcareous phosphates were studied. Considerable upgrading of the ores I and II was obtained from 18.1 to 29.8% P 2O 5 and from 17.0 to 27.3% P 2O 5, but little was achieved with sample III.