FUNDAMENTAL-ASPECTS OF SOLUBLE SALT FLOTATION

The sign of the surface charge for alkali halides in their saturated b rines has been established from nonequilibrium electrokinetic measurem ents. These surface charge results for alkali halides are generally as expected from simplified lattice ion hydration theory. Based on this electrokinetic information, it has been demonstrated that the flotatio n of alkali halide salts is due to the adsorption of oppositely charge d collector colloids by heterocoagulation. For example, the classic fl otation separation of KCl from NaCl with alkyl amines is thus explaine d. Now, the surface charge/collector colloid adsorption hypothesis has been extended to succesfully explain the flotation behavior of certai n alkali oxyanions including nitrates and sulfates as well as double s alts including schoenite (K2SO4.MgSO4.6H(2)O) and kainite (KCl.MgSO4.3 H(2)O). As was done previously for the alkali halides, the sign of the surface charge for these alkali oxyanion salts was established from n onequilibrium electrokinetic measurements by laser-doppler electrophor esis. These results together with the results from flotation/bubble at tachment experiments indicate that the surface charge/collector colloi d adsorption hypothesis accounts for the flotation response of many di fferent soluble salt minerals when alkyl amines and carboxylates are u sed as collectors.