植物油脂捕收剂强化低阶煤浮选作用机理及其构效关系

Mechanism and structure-activity relationship of vegetable oil collectors to enhance the low rank coal flotation

低阶煤的大规模分选利用产生大量细粒难浮煤泥,开发使用含极性组分的浮选捕收剂可精准调控低阶煤颗粒表面疏水性,实现细粒难浮煤泥的浮选过程强化。研究了2种植物油脂JC61、JC62以及柴油的物理化学性质及低阶煤浮选效果差异,借助宏观表征试验探索了不同捕收剂对低阶煤润湿性的影响,进而理论计算总结了酯类捕收剂分子对应浮选的构效关系。浮选试验结果表明:用量为2000 g/t时,JC62、JC61、柴油的浮选精煤产率分别为24.11%、76.03%、89.92%,2种植物油脂捕收性能均显著优于柴油。XPS测试发现JC61、JC62与颗粒作用可减少亲水基团的相对含量,且JC62效果更优。而JC61成分以C16~C20饱和脂肪酸乙酯为主,而JC62主要为含有不饱和双键的油酸甲酯。2种植物油脂中主要的酯类分子均可与低阶煤亲水性羧基形成氢键,十二烷、油酸甲酯、油酸乙酯、十六酸甲酯、十六酸乙酯的吸附能分别为-95.64、-127.71、-124.73、-121.05、-24.17 kJ/mol,即作用强度为:甲酯>乙酯、不饱和酯类>饱和酯类。在酯类捕收剂分子结构中,含有极性酯类头基的分子可与低阶煤官能团自发形成氢键,且甲酯的作用更强;疏水碳链上不饱和C=C键的存在增强了分子的极性,促进了酯类分子在低阶煤亲水位点的作用。

The large-scale separation and utilization of low rank coal generates a large amount of fine-grained and difficult to float coal slime.The development and use of flotation collectors containing polar components can accurately regulate the surface hydrophobicity of low rank coal particles,achieving enhanced flotation process of fine-grained and difficult to float coal slime.The physical and chemical properties of two kinds of vegetable oils JC61,JC62 and diesel oil as well as the flotation effect of low rank coal were studied,and the influence of different collectors on the wettability of low rank coal was explored by means of macroscopic characterization tests.Further,the Structure-activity relationship of ester collectors corresponding to flotation was summarized by theoretical calculation.The flotation test results showed that at a dosage of 2000 g/t,the flotation concentrate yields of JC62,JC61,and diesel were 24.11%,76.03%,and 89.92%,respectively.The collection performance of the two vegetable oils was significantly better than that of diesel.XPS testing found that JC61 and JC62 interact with particles to reduce the relative content of hydrophilic groups,and JC62 has a better effect.The composition of JC61 is mainly C16~C20 Saturated fat acid ethyl ester,while JC62 is mainly methyl oleate containing unsaturated double bonds.The main ester molecules in both plant oils can form hydrogen bonds with low rank coal hydrophilic carboxyl groups.The adsorption energies of dodecane,methyl oleate,ethyl oleate,methyl hexadecylate,and ethyl hexadecylate are-95.64,-127.71,-124.73,-121.05,and-24.17 kJ/mol,respectively.The law of action intensity is:methyl ester>ethyl ester,unsaturated ester>saturated ester.In the molecular structure of ester collectors,the molecules containing polar ester head groups can spontaneously form hydrogen bonds with lower rank coal functional groups,and the role of methyl ester is stronger.The presence of unsaturated C=C bonds on hydrophobic carbon chains enhances the polarity of molecules and promotes the role of ester molecules at low rank coal hydrophilic water level points.