APAM和CTAB强化低阶动力煤过滤机理研究

Study on the filtration mechanism of APAM and CTAB enhanced low-rank power coal

低阶动力煤包含较多细粒级和黏土矿物,导致其煤泥过滤难度增加。选用阴离子型聚丙烯酰胺(APAM)和十六烷基三甲基溴化铵(CTAB)作为助滤剂强化煤泥过滤,并利用低场核磁共振技术检测滤饼孔隙变化,采用Zeta电位仪、聚焦束反射测量仪、接触角测量仪、表面张力仪和X射线光电子能谱表征煤颗粒和滤液性质。结果表明,助滤剂提高了过滤速率并降低了滤饼水分;CTAB能够显著提高煤表面疏水性、大幅降低滤液表面张力,但仅使滤饼孔隙率提高2.65%;APAM显著降低了颗粒Zeta电位,将絮体尺寸增大约7~9μm,使滤饼孔隙率提高11.65%;CTAB主要通过“润滑”滤饼孔壁增强孔壁疏水性以促进煤泥过滤脱水,而APAM主要通过削弱颗粒间的静电排斥力,促进絮体的形成以提高滤饼孔隙率强化煤泥过滤。

Low-rank power coal contains more fine-grained and clay minerals,which leads to its increased filtration difficulty.Anionic polyacrylamide(APAM)and cetyltrimethylammonium bromide(CTAB)were selected as filtration aids to enhance coal slurry filtration.Low-field NMR technique was used to detect the pore changes of the filter cake,and zeta potential meter,focused beam reflectometry,contact angle meter,surface tension meter and X-ray photoelectron spectroscopy were used to characterize the coal particles and filtrate properties.The results showed that the filtering aid improved the filtration rate and reduced the cake moisture,CTAB significantly improved the hydrophobicity of coal surface and reduced the surface tension of filtrate,but only increased the cake porosity by 2.65%,APAM significantly reduced the particle zeta potential and increased the floc size by about 7~9μm,which increased the cake porosity by 11.65%.The mechanisms of APAM and CTAB to strengthen coal slurry filtration and dewatering are different,CTAB mainly promotes coal slurry filtration and dewatering by lubricating the pore wall of the filter cake and enhancing the hydrophobicity of the pore wall,while APAM mainly strengthens coal slurry filtration by weakening the electrostatic repulsive force between particles and promoting the formation of flocs to increase the pore rate of the filter cake.