基于紫外活化的柴油强化低阶煤浮选动力学

Kinetics of low-rank coal enhanced flotation with diesel oil based on ultraviolet activation

常规传统烃油类捕收剂活性低,难以实现低阶煤浮选提质,采用紫外线对柴油进行活化处理,系统研究了捕收剂用量与紫外活化时间对低阶煤浮选动力学的影响规律,并使用经典一级动力学模型、一级矩阵分布模型、经典二级动力学模型、二级矩阵分布模型、全粒级混合反应模型与改进气固黏附模型6种浮选动力学模型对浮选试验结果进行拟合分析。结果表明:增加紫外活化时间,可大幅度提高精煤可燃体回收率,以紫外活化时间为12 h为例,当捕收剂用量为2,4,6和8 kg/t时,可燃体回收率相对于未活化时分别提高了39.9%,45.4%,43.2%和39.0%;同时,发现紫外活化药剂可降低精煤灰分,增强浮选选择性。由气相色谱质谱联用(GC-MS)测试图可知,紫外活化处理,显著增加了柴油中的羧基、羟基、羰基等含氧官能团数量,其中醇类物质增加最多,含氧物质增强柴油的电负性与极性,可使捕收剂分子通过氢键吸附于低阶煤表面亲水位点,增强低阶煤表面疏水性;同时柴油中非极性物质烷烃、烯烃优先与煤表面非极性位点吸附,2者作用于煤粒不同位点,协同提高精煤回收率。随着紫外活化时间的延长,浮选速率常数增大,反应速率加快(2 min后回收率趋于饱和)。对6种浮选动力学模型拟合结果进行比较,发现经典一级动力学模型其相关系数平方和R2(可达99.96%以上)与误差平方和SSE拟合度更高,为最合适模型;浮选结果与拟合结果匹配度最高,为最优模型。

Conventional hydrocarbon oil collectors have low activity,and it is difficult to improve the quality of low-rank coal by flotation.The effects of collector dosage and ultraviolet activation time on the flotation kinetics of low rank coal were systematically studied,and the results of flotation test were fitted by six kinds of flotation kinetic models:the classical first-order model,the first-order model with rectangular distribution,the classical second-order kinetic model,the second-order model with rectangular distribution,the fully mixed reaction model and the improved gas-solid adsorption model.The results show that the recovery rate of coal can be greatly increased by increasing the ultraviolet activation time.Taking the ultraviolet activation time 12 h as an example,when the collector dosage is 2,4,6 and 8 kg/t,the recovery of combustible was increased by 39.9%,45.4%,43.2%and 39%,respectively,compared with the normal coal.The results of gas chromatography-mass spectrometry(GC-MS)showed that the number of carboxyl,hydroxyl and carbonyl functional groups in diesel oil was increased by UV activation,and the alcohol increased the most,oxygen-containing substances can enhance the electronegativity and polarity of diesel oil,and the collector molecules can be adsorbed on the surface of low-rank coal through hydrogen bond,thus enhancing its surface hydrophobicity.At the same time,the non-polar matter alkanes and olefins in diesel oil adsorb preferentially with the non-polar sites on the surface of coal,and they act on different sites of coal particles to improve the recovery rate of clean coal.With the extension of UV activation time,the flotation rate constant increases and the reaction rate speeds up(the recovery tends to saturation after 2 min).By comparing the fitting results of six flotation kinetic models,it is found that the multitude correlation coefficients R2(up to 99.96%)and the sum of squares due to error SSE are the most suitable ones.The best match between flotation result and fitting result is the optimal model.