低阶煤油泡浮选过程特征及其动力学研究

发布时间：2018-09-01 14:13

【摘要】：我国的低阶煤资源十分丰富,约占我国煤炭资源量的45.68%,低阶煤资源的清洁高效开发利用对保障我国能源安全及经济发展具有重要意义。低阶煤天然可浮性差,遇水易泥化,浮选药剂消耗量大,阻碍了低阶煤浮选的工业化应用。为解决低阶煤浮选的难题,采用油泡浮选方法,可有效促进低阶煤颗粒矿化,提高低阶煤的回收率。目前,有关低阶煤与油泡的矿化机理还不清楚,对低阶煤可浮性的变化特征缺乏深入了解,本文以神东矿区的低阶煤煤泥为研究对象,围绕低阶煤油泡浮选过程特征及其动力学进行深入的研究,探讨低阶煤油泡浮选机理,为低阶煤浮选的工业化提供理论基础和技术支撑。通过SEM、FT-IR、XPS、XRD等现代分析测试手段全面分析了低阶煤的煤质特性,结果表明:低阶煤煤样总体呈现细泥含量大,灰分高的特点,表面有很多孔隙和凹陷,煤泥表面的含氧官能团主要为羟基-OH和醚键C-O,以及少量的羧基O=C-O和羰基C=O。低阶煤中的杂质矿物主要为石英、高岭石和白云母,其它矿物较少,煤泥接触角为40.8°,属于中等可浮性煤泥。利用响应面分析方法对低阶煤油泡浮选工艺参数进行了优化。通过单因素试验和Box-Behnken试验得到了最优的油泡浮选工艺条件为:浮选机转速2152.50r/min、捕收剂用量4.35kg/t、矿浆浓度56.00g/L、充气量0.22m3/h,获得的最大可燃体回收率为96.53%。探索了低阶煤油泡浮选药剂耗量的最低限度,通过对模型参数捕收剂用量的优化,当最小药剂用量2.32kg/t时最大可燃体回收率为84.32%,常规浮选的方法捕收剂用量为50kg/t,精煤产率达到68.62%,可燃体回收率为88.18%。与常规浮选方法相比,低阶煤浮选效果及其捕收剂耗量明显改善。从浮选速率角度出发,研究了气泡、冷态油泡和热态油泡浮选以及不同粒级煤泥油泡浮选过程特征,结果表明:常规浮选的浮选速率常数随浮选时间不断减小,而油泡浮选的浮选速率随浮选时间不断增大,冷态油泡浮选的效果好于常规浮选。雾化有利于捕收剂均匀地分散矿浆中,高温闪蒸更有利于油泡的形成,以及颗粒与气泡矿化。各粒级浮选速率从大到小顺序为:0.125~0.074mm粒级-0.074mm粒级0.25~0.125mm粒级0.25~0.5mm粒级,即粒度细且灰分低的颗粒浮选速率较快。普通气泡浮选低阶煤的过程接近于经典一级浮选动力学模型,通过在浮选动力学模型中增加一个时间参数t*,提高了浮选动力学模型对油泡浮选过程的适应能力,低阶煤油泡浮选速率更符合修正后的经典一级浮选动力学模型。从油泡特性、动力学以及热力学角度研究了油泡浮选行为机理,结果表明:油泡的泡沫稳定性较强,油泡浮选水流夹带作用较小,通入闪蒸烃类捕收剂会减少气泡的产生数量。油泡对低阶煤的诱导时间明显比气泡小,油膜厚度的增加能够缩短诱导时间,粒度越细的颗粒诱导时间越短,缩短诱导时间将会明显提高粘附概率,颗粒与油泡之间的矿化能垒较小,有利于粘附过程。
[Abstract]:China is rich in low-rank coal resources, accounting for about 45.68% of China's coal resources. Clean and efficient development and utilization of low-rank coal resources is of great significance to energy security and economic development in China. At present, the mineralization mechanism of low-rank coal and oil bubbles is still unclear, and the variation characteristics of low-rank coal flotability are lack of in-depth understanding. The characteristics and kinetics of oil bubble flotation process were studied in depth, and the mechanism of low-rank kerosene bubble flotation was discussed. The theoretical basis and technical support were provided for the industrialization of low-rank coal flotation. The oxygen-bearing functional groups on the surface of coal slime are mainly hydroxyl-OH and Ether-Bonded C-O, and a small amount of carboxyl O=C-O and carbonyl C=O. Impurity minerals in low rank coal are mainly quartz, kaolinite and muscovite, and other minerals are less. The contact angle of coal slime is 40.8 degrees, belonging to medium floatable slime. The optimum technological parameters of low-order kerosene bubble flotation were obtained by single factor test and Box-Behnken test. The optimum conditions of bubble flotation were as follows: the speed of flotation machine was 2152.50r/min, the dosage of collector was 4.35kg/t, the slurry concentration was 56.00g/L, and the aeration capacity was 0.22m3/h. The maximum combustible recovery was 96.53%. The minimum reagent consumption of low-order kerosene bubble flotation was explored. By optimizing the dosage of model parameter collector, the maximum combustible recovery rate was 84.32% when the minimum reagent dosage was 2.32 kg/t, the conventional flotation method was 50 kg/t, the concentrate yield was 68.62%, and the combustible recovery rate was 88.18%. The flotation efficiency of low-rank coal and the consumption of collectors are improved obviously. From the point of view of flotation rate, the flotation characteristics of bubbles, cold oil bubbles, hot oil bubbles and slime oil bubbles with different particle sizes are studied. The results show that the flotation rate constant of conventional flotation decreases with the flotation time, while the flotation rate of oil bubbles decreases with the flotation time. The atomization is favorable for the collector to disperse evenly in the pulp, and the flash at high temperature is more conducive to the formation of oil bubbles and the mineralization of particles and bubbles. The flotation process of low-rank coal by ordinary bubble is close to the classical first-order flotation kinetic model. By adding a time parameter t*, the adaptability of the flotation kinetic model to the oil bubble flotation process is improved, and the low-rank kerosene bubble flotation rate is more in line with the revised one. The mechanism of oil bubble flotation behavior was studied from the point of view of oil bubble characteristics, kinetics and thermodynamics. The results show that the stability of oil bubble is stronger, the entrainment effect of oil bubble flotation water is smaller, and the number of bubbles can be reduced by introducing flash hydrocarbon collector. The smaller the bubbles are, the shorter the induction time is. The shorter the induction time is, and the shorter the induction time is, the higher the adhesion probability is. The smaller the mineralization barrier between the particles and the bubbles, which is beneficial to the adhesion process.
【学位授予单位】：中国矿业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD94;TD923

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