Enhanced flotation separation of aluminum electrolysis anode slag via microemulsification of diesel collector

Abstract

Aiming at the defects such as poor dispersion and high consumption of conventional diesel collector in the flotation process of aluminum electrolysis anode carbon slag (CS), a microemulsion diesel collector was prepared, and its performance and mechanism in CS flotation were investigated by means of flotation experiments as well as modern analysis methods (surface tension, laser particle size, zeta potential, FTIR, etc.). A complex of sorbitan monooleate (Span 80) and cetyltrimethylammonium bromide (CTAB) was used as the primary surfactant, and the optimal formulation of the microemulsion collector was HLB of 8, co-surfactant of n-butanol, Km of 1.7, and oil-surfactant-water mass ratio of 27.80:27.8:44.40, and the droplet size of the obtained microemulsion collector was 62.22 nm. The flotation results showed that a carbon recovery of 74.48 % was obtained at a microemulsion collector dosage of 400 g/t, which resulted in a collector saving of 66.67 % with similar flotation indexes. The flotation process of microemulsion diesel for CS is in accordance with the classical first-level kinetic model, and its flotation rate is faster than that of conventional diesel. Analysis test results showed that microemulsification resulted in smaller droplet size and better dispersion of diesel collector in water, which enhanced its adhesion to carbon particles even at low reagent dosage. At the same time, the microemulsion diesel reduces the electronegativity of the CS particles and enhances the coverage of oxygenated functional groups on the carbon surface, thus enhancing the hydrophobicity of the carbon particles and improving its flotation recovery performance. This research can provide new theoretical basis and technical support for efficient waste disposal and resource recovery for CS.