煤表面热力学特性的Washburn动态法测试

微细粒中煤浮选的突出问题是选择性差、精煤产品灰分高，而润湿性是影响微细颗粒分选重要的界面性质，基于此，考察了煤样与主要杂质矿物高岭石的表面热力学特性。用Washburn动态法，以正己烷、1-溴萘、甲酰胺、去离子水为液体分子探针测量其对不同密度级微细粒中煤样品及高岭石的润湿过程，用线性回归法分析润湿速率并计算亲油亲水比，联合Washburn方程和van Oss-Chaudhury-Good理论对不同密度级煤粉样品以及高岭石的表面自由能进行估算，并进行煤泥的分布释放实验。研究表明：随煤样密度级的增加，正己烷对煤样的润湿速率降低，且变化不大，去离子水对煤样的润湿速率增高，两者对高岭石的润湿速率分别为0.010 1，0.020 6 g2/s，远大于对煤样的润湿速率；煤样随密度级的增加亲油亲水比值LHR值减小，1.5~1.6 g/cm3与1.6~1.8 g/cm3中间密度级煤样的润湿速率和LHR值相近，高岭石的LHR值最低，为1.44，呈亲水性；各个密度级样品的非极性成分γLWs呈略微降低趋势且其值基本一致，均低于高岭石的γLWs，样品表面自由能极性成分中氢键作用的碱性力与LHR值呈正相关。该煤样分布释放浮选实验结果与各个密度级样品表面性质测试结果吻合。

Surface thermodynamic characterization of fine coal by Washburn dynamic method

The poor selectivity and high ash content of clean coal are the prominent issues in fine coal flotation.Wettability is one of the important interface properties affecting the fine coal flotation.Thermodynamic characterization of fine coal and main impurity mineral kaolinite was investigated in this study.Washburn dynamic method was used to study the wetting process of different density level coal samples and kaolinite wetted by n hexane，1 bromine naphthalene，formamide and water as liquid molecular probe.Wetting rate and lipophilic hydrophilic ratio (LHR) was calculated by linear regression analysis method.Washburn equation and van Oss Chaudhury Good theory were used to estimate the surface free energy components of samples.The results show that n hexane wetting rate of coal samples decreases with the increase of density level which is slight，but deionized water wetting rate of coal samples increases.The wetting rates of kaolinite wetted by n hexane and water are 0.010 1 and 0.020 6 g2/s respectively，however，they are higher than that of coal samples.The LHR of kaolinite is 1.44 and kaolinite is hydrophilic；the LHR of coal samples increases with the increase of density level.The middle density level coal sample of 1.5-1.6 g/cm3 and 1.6-1.8 g/cm3 with similar wetting rates and LHR values are hydrophobic.Surface free energy polar component γLWs of each density level of coal samples reduces slightly and is all lower than γLWs of kaolinite.Furthermore，the alkaline force of the sample surface free energy polar components，which is of hydrogen bonding interaction，is correlated to LHR value.The results of regressive release flotation test coincides well with the coal sample surface properties.