自吸气浮选预处理装置的参数优化和试验研究

发布时间：2019-03-17 14:49

【摘要】：本文结合现有煤泥浮选设备的优点,引入了水轮机的工作原理,提出了一种新型自吸气浮选预处理装置,并对该装置进行了理论分析、参数优化和试验测试。自吸气浮选预处理试验装置的设计原则是保证充足的吸气量,保证恒定的转速和稳定的流场,其工作原理是将矿浆通过矿浆泵引入管道,在喷嘴处高速喷射冲击到叶轮叶片上,叶轮受迫高速转动,并将矿浆甩出,叶轮体内形成局部负压状态,在压差作用下,外界空气通过顶端的吸气口进入装置内部,并通过叶轮的搅拌作用与矿浆充分混合,形成气液固三相流,从装置下端的排料口排出,实现浮选矿浆的预处理。理论分析部分,对自吸气浮选预处理装置的总体参数和射流冲击、负压吸气两个阶段进行了理论分析,针对喷嘴射流运动、水流冲击叶轮的力矩,水流进出叶轮体的速度以及吸气量进行了具体的分析计算;试验测试阶段,搭建模型、选取部件及配件,制定试验,对喷嘴直径和叶轮叶片个数进行了参数优化,并探究了入料流量、入料压力、叶轮转速和吸气口吸气量之间的关系,最后进行了气泡测试试验和煤泥分选试验。结果表明:(1)叶轮叶片个数为8个,喷嘴直径为5mm时,叶轮转速和吸气口吸气量的效果能达到最好,且叶轮转速和吸气量之间存在明显的正相关关系。(2)调整变频器频率可直接改变叶轮的转速,随着叶轮转速的上升,入料流量和入料压强以及叶轮转速和吸气量都稳步上升,变频器频率为40Hz时,入料流量为0.56m3/h,入料压强为0.18MPa,叶轮转速为544.3r/min,吸气口吸气量为3.5L/min,接着提升变频器频率,各项指标无明显变化;(3)自吸气浮选预处理装置能够产生足够量的微小气泡,符合正态分布,大于1mm的气泡占比极小,大大提高了气泡群的稳定性,适合应用于浮选预处理工作;经叶轮切割后,气泡平均直径最小可低至0.5161mm,且0.5mm左右的气泡所占比例突破0.4,小气泡所占比例增加,叶轮的切割作用效果显著;足够的冲击动能有助于形成微小的气泡,而稳定的流场可以抑制气泡的兼并。(4)煤泥分选试验中,经过浮选预处理装置,可将精煤产率最高提升4.8%,在低频率条件下精煤产率较低,而随着工作频率的升高,精煤产率也升高,50Hz和40Hz工作频率下的精煤产率差别不大。浮选预处理装置对精煤灰分并无明显的影响。
[Abstract]:Combined with the advantages of existing slime flotation equipment, this paper introduces the working principle of hydraulic turbine, puts forward a new type of self-suction flotation pretreatment device, and carries out theoretical analysis, parameter optimization and experimental test of the device. The design principle of self-suction flotation pretreatment test device is to ensure adequate gas absorption, constant rotating speed and steady flow field. Its working principle is that the slurry is introduced into the pipeline through slurry pump, and the high-speed injection is on the impeller blade at the nozzle. The impeller is forced to rotate at high speed, and the slurry is thrown out of the impeller, and the impeller forms a state of local negative pressure. Under the action of pressure difference, the external air enters the inner part of the device through the suction port at the top, and it is fully mixed with the slurry through the stirring action of the impeller. Gas-liquid-solid three-phase flow is formed and discharged from the discharge port at the lower end of the device to realize the pretreatment of flotation pulp. In the theoretical analysis part, the general parameters, jet impingement and negative pressure suction of the self-suction flotation pretreatment device are analyzed theoretically, aiming at the jet motion of the nozzle and the torque of the impingement impeller. The velocity of water flow in and out of the impeller body and the air absorption rate are analyzed and calculated in detail. The parameters of nozzle diameter and the number of impeller blades are optimized, and the relations among feed flow rate, feed pressure, impeller speed and suction capacity are also discussed, and the relationship between feed flow rate, feed pressure, impeller speed and suction capacity is discussed, and the parameters of the nozzle diameter and the number of impeller blades are optimized in the test and test stage. Finally, bubble test and slime separation test were carried out. The results show that: (1) when the number of impeller blades is 8 and the diameter of nozzle is 5mm, the effect of impeller speed and air suction is the best. And there is a significant positive correlation between impeller speed and air absorption. (2) adjusting the frequency of frequency converter can change the speed of impeller directly, and with the increase of impeller speed, the speed of impeller can be changed directly by adjusting the frequency of frequency converter. When the frequency of frequency converter is 40Hz, the feed flow rate is 0.56 m3 / h, the feed pressure is 0.18 MPA, the speed of impeller is 544.3 rmin, the feed flow rate is 0.56 m ~ 3 / h, the feed pressure is 0.18 MPA, and the impeller speed is 544.3 r / min. The suction volume was 3.5 L / min, then the frequency of frequency converter was raised, and the indexes had no obvious change. (3) the self-suction flotation pretreatment device can produce sufficient micro bubbles, which accord with normal distribution, and the ratio of bubbles larger than 1mm is very small, which greatly improves the stability of bubble group and is suitable for flotation pretreatment. After the impeller is cut, the average diameter of bubbles can be at least as low as 0.5161mm, and the proportion of bubbles around 0.5mm is more than 0.4, the proportion of small bubbles is increased, and the cutting effect of impeller is remarkable. Sufficient impact kinetic energy helps to form tiny bubbles, while stable flow fields can inhibit bubble annexation. (4) in slime separation experiments, the maximum yield of refined coal can be increased by 4.8% after flotation pretreatment. Under the condition of low frequency, the yield of clean coal is low, but with the increase of working frequency, the yield of clean coal also increases, and there is little difference between 50Hz and 40Hz working frequency. The flotation pretreatment device has no obvious effect on the ash content of clean coal.
【学位授予单位】：安徽理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TD456;TD94

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