Enhanced flotation mechanism of coal gasification fine slag with composite collectors

In this study, different composite collectors were used to analyze the flotation separation of residual charcoal and ash materials in fine coal gasification slags. The effects of collector type, stirring speed, and conditioning time on the flotation separation were investigated. The experimental results showed that composite collectors containing dodecylamine polyoxyethylene ether (AC1201) and kerosene could effectively separate charcoal-ash when treating the fine coal gasification slags of Ningxia Coal Industry Company. The ash content of the residue carbon product was approximately 60%, and that of the ash material product was more than 95%. Compared with kerosene, AC1201-kerosene collector can be dispersed more easily and lower interfacial tension in collector-deionized water system, resulting in better selectivity of the collector. The composite collector containing 15% AC1201 has stronger adsorption on residual charcoal compared with kerosene at the same dose, owing to electrostatic mechanism. The addition of AC1201 in kerosene resulted in better adsorption on residual charcoal than ash material, the hydrophobicity difference of two materials can be further expanded, resulting in increased tailings ash and combustible recovery. The flotation products, including the concentrate and tailings of fine coal gasification slag, were evaluated by means of infrared spectrum analysis, X-ray photoelectron spectroscopy (XPS) analysis, and scanning electron microscope energy spectrometer (SEM-EDS) to characterize the different compositions and elemental distributions. The results of this study provide a reference for analyzing charcoal-ash flotation separation and its mechanism.