Effect of cationic-anionic surfactant synergistic non-polar oil on low-rank coal flotation

In order to improve the wettability difference between organic matter and inorganic matter in low-rank coal, thereby improving the flotation efficiency of low-rank coal, cationic surfactants dodecyl trimet hylammonium bromide (DTAB) and anionic surfactants dodecyl alcohol polyoxyethylene ether sodium sulfate (AES) and non-polar collector kerosene are compounded to obtain a compound collector. Study the adsorption and aggregation characteristics of surfactants by measuring the surface chemical properties of the composite system and calculating the synergistic parameters; using flotation experiments to study the effect of different composite collectors on the flotation effect and through the flotation kinetics experiments to study the flotation rate and flotation selectivity of a single-use of kerosene collector and use of compound collector; Zeta potential measurement experiment, wetting heat measurement experiment, and contact angle measurement experiment to study the improvement of compound collectors floatability mechanism of low-rank slime. Experimental results show that：DTAB and AES compound system has a synergistic effect in reducing surface tension efficiency and ability. Compared with the single use of kerosene as the collector, the flotation yield of the combined collector increased from 18.64% to 69.86%, the flotation perfection increased from 7.79% to 18.00%, and the ash content of clean coal increased by 2.89%. Compared with kerosene, the compound collector can significantly increase the flotation speed of low-rank coal. The flotation rate constant is increased from 0.010 0 to 0.034 5, and the selectivity is also increased. In the compound collector (kerosene+DTAB+AES), the improvement degree of organic hydrophobicity by different ratios of agents from large to small is n(DTAB)∶n(AES)＝1∶1, 0∶1, 1∶0. The order of enlarging the difference of wettability between organic matter and inorganic matter from large to small is n(DTAB)∶n(AES) ＝ 1∶1, 1∶0, 0∶1. In the compound collector, DTAB and AES are combined to form ion pairs, and the ethoxy group (—CH2—CH2—O—) contained in it can form hydrogen bonds with oxygen-containing functional groups and firmly adsorb on the surface of low-rank coal; after association the formedion pairs and a small amount of free DTAB ions will expose the hydrophobic chain of the surfactant after adsorption, thereby masking the polar sites on the surface of low-rank coal; non-polar kerosene can not only adsorb on the hydrophobic sites on the surface of low-rank coal itself, it is also adsorbed on the non-polar sites exposed after the agent covers the polar sites, thereby promoting the spreading of kerosene on the surface of organic matter and greatly improving the flotation effect.