New insights of composite collector comprised of kerosene and a non-ionic surfactant for coal gangue flotation decarbonization: Experiment, characterization and molecular dynamics simulation

Reasonable and efficient flotation decarbonization of coal gangue is regarded as one of the effective ways to achieve its comprehensive utilization. In this work, the orbital energy difference indicated that composite collector comprised of kerosene and a non-ionic surfactant fatty alcohol polyoxyethylene (9) ether (AEO−9) had the ability to maintain stable adsorption of mineral, and also occurred certain chemical reactivity and the AEO−9 molecule could spontaneously interact with kerosene. The flotation tests were designed and optimized using the response surface methodology under a two-stage opened-circuit flotation process, and a quadratic polynomial model could accurately predict the actual value by the diagnostic analysis. A favorable indicator of carbon content of 72.31 % and carbon recovery rate of 50.84 % for the flotation concentrate was obtained under the conditions of pH 8.5, 15 kg/t composite collector composed of kerosene and 50 mg/L surfactant AEO-9, and 120 g/L slurry concentration. XRD SEM-EDS mapping analysis and contact angle measurement revealed that the coal gangue flotation decarbonization process assisted by the regeneration composite collector could effectively remove impurities and enrich the refined coal into the flotation concentrate. The dynamic behavior of surfactant and diffusion coefficient in the local oil-water interface both showed that the hydrophilic tail chain moieties of AEO-9 molecule were partially insert into the external water phase, exposing a number of polyoxyethylene ether groups in the oil-water interface and possessing a high spreading performance. The dynamic behavior of the coal-oil-water system showed that the AEO-9 molecule was more likely to expel the hydration layer and could be spontaneously adsorbed on the surface of coal particles.