同轴旋转磁场对重介质旋流器分选效果影响规律研究.pdf

A Dissertation ted to Taiyuan University of Technology In partial fulfillment of the requirement For the degree of Master Research on the Influence of Coaxial Rotating Magnetic Field on the Separation Effect of Dense Medium Cyclone By HUI REN School of Chemistry and Chemical Engineering June 2021 学位论文原创性声明 本人郑重声明所呈交的学位论文，是本人在导师的指导下，独 立进行研究所取得的成果。除文中已经注明引用的内容外，本论文不 包含其他个人或集体已发表或撰写过的科研成果。 对本文的研究做出 贡献的个人和集体，均已在文中以明确方式标明。本声明的法律责任 由本人承担。 论文作者签名 签字日期 年 月 日 学位论文版权使用授权书 本学位论文作者和指导教师完全了解太原理工大学有关保留、 使 用学位论文的规定 学校有权保留并向国家有关部门或机构送交学位 论文的复印件和电子版；允许本学位论文被查阅和借阅；学校可以将 本学位论文的全部或部分内容编入有关数据库进行检索， 可以采用影 印、缩印或其他复制手段保存和汇编本学位论文。 本学位论文属于 保密 □ 在 年解密后适用本授权书 不保密□ 论文作者签名 导师签名 签字日期 年 月 日 签字日期 年 月 日 学位论文答辩信息表 论文题目 同轴旋转磁场对重介质旋流器分选效果影响规律研究 答辩日期 2021.6.9 答辩秘书 杨宏丽 学位论文答辩委员会成员 姓名 职称 工作单位 备注 王怀法 教授 太原理工大学 主席 董连平 副教授 太原理工大学 委员 李志红 副教授 太原理工大学 委员 摘 要 I 摘 要 近年来利用在重介质旋流器上附加外置磁场调节其分选效果的研究取得了 一定成效， 但静态磁场不能调控重介质悬浮液的切向速度，静态磁场对重介质旋 流器的调控是不全面的。 为了进一步优化磁场对重介质旋流器分选密度的在线调 控， 笔者尝试通过外加旋转磁场影响重介旋流器内部流场与密度场的方式，进而 调节旋流器的分选特性。 采用将永磁铁同轴置于重介质旋流器筒体处、锥部的不同位置处、底流口处 的方法，采用三相异步电机来控制磁铁的旋转速度及旋转方向，在无磁场、静态 磁场、 永磁铁旋转方向与矿浆旋转方向一致、永磁铁旋转方向与矿浆旋转方向相 反的四种状态下进行-3mm 粗煤泥分选试验。选取了距离筒锥交界面 120mm 处 的无磁场、静态磁场、永磁铁旋转方向与矿浆旋转方向一致时转速为 851r/min、 永磁铁旋转方向与矿浆旋转方向相反时转速为 421r/min 的四个试验点进行重选 效果评定，并利用 AnsysMaxwell 分析软件对静态磁场进行模拟分析。 将永磁铁置于重介质旋流器各个位置时，静态磁场与无磁场时相比，各粒级 精煤与尾煤灰分均降低。当永磁铁置于筒体处时，永磁铁旋转方向与矿浆旋转方 向一致和相反时的试验结果无明显差异，永磁铁旋转时与静态磁场时相比，各粒 级精煤灰分均降低，各粒级尾煤灰分均提高；当永磁铁位于旋流器锥体上部时， 具体位置为永磁铁距离筒锥交界面 80mm、120mm、160mm 处的试验结果基本 一致， 磁铁旋转方向与矿浆旋转方向一致时与静态磁场相比，各粒级精煤与尾煤 灰分均提高，永磁铁旋转方向与矿浆入料方向相反时与静态磁场相比，各粒级精 煤灰分均降低，各粒级尾煤灰分均提高；当永磁体位于旋流器锥体下部，距离筒 锥交界面 240mm 处时，磁铁旋转方向与矿浆旋转方向一致时与静态磁场相比， 各粒级精煤与尾煤灰分均提高， 当永磁铁旋转方向与矿浆旋转方向相反时与静态 磁场相比， 各粒级精煤灰分均降低，各粒级尾煤灰分波动式变化与静态磁场时的 尾煤灰分相差不大；距离筒锥交界面 300mm 处时，永磁铁旋转方向与矿浆旋转 方向一致和相反时的试验结果基本一致，永磁铁旋转时与静态磁场时相比，各粒 级精煤与尾煤灰分均提高；当永磁铁置于底流口处时，永磁铁旋转方向与矿浆旋 转方向一致和相反时的试验结果无明显差异，永磁铁旋转与无磁场时相比，精煤 与尾煤灰分均提高。 由重选效果评定结果可知 δp（无磁）δp851 δp-421 δp静态； Ep（无磁）Ep（静态）≈Ep （851）Ep（-421）。 静态磁场时的分选密度比无磁场时的分选密度降低了 0.09g/cm3， Ep值降低了 0.0134 g/cm3，分选精度提高；永磁铁旋转方向与矿浆旋转方向一致 太原理工大学硕士学位论文 II 且转速为 851r/min 时的分选密度比静态磁场时的分选密度提升了 0.03g/cm3，分 选精度基本不变；永磁铁旋转方向与矿浆旋转方向相反且转速为 421r/min 时的 分选密度比静态磁场时的分选密度提升了 0.012g/cm3，Ep值降低了 0.0103g/cm3， 分选精度大幅提升。利用 AnsysMaxwell 分析软件初步揭示了置于锥部的永磁体 可以降低重介质旋流器分选密度的原因是 斜向下的磁力将更多的磁铁矿粉吸引 到底流口，并从底流口排除，从而降低了重介质旋流器的分选密度。 关键词关键词重介质旋流器；分选密度；永磁场；旋转速度；磁场模拟 ABSTRACT III ABSTRACT In recent years, the study of using an external magnetic field to adjust the separation effect of the dense medium cyclone has achieved certain results, but the static magnetic field cannot control the tangential velocity of the dense medium suspension, and the static magnetic field controls the dense medium cyclone is not comprehensive. In order to further optimize the on-line control of the magnetic field on the separation density of the dense-medium cyclone, the author tried to influence the internal flow field and density field of the dense-medium cyclone by adding a rotating magnetic field to adjust the separation characteristics of the cyclone. Adopt the of coaxially placing the permanent magnet at the barrel of the dense medium cyclone, at different positions of the cone, and at the underflow port. A three-phase asynchronous motor is used to control the rotation speed and direction of the magnet. The -3mm coarse coal slime separation test was carried out under four conditions the magnetic field, the rotation direction of the permanent magnet is consistent with the rotation direction of the slurry, and the rotation direction of the permanent magnet is opposite to the rotation direction of the slurry. Selected four no magnetic field, static magnetic field at a distance of 120mm from the interface of the barrel and cone, the rotation speed of the permanent magnet is 851r/min when the rotation direction of the permanent magnet is consistent with the rotation direction of the slurry, and the rotation speed is 421r/min when the rotation direction of the permanent magnet is opposite to the rotation direction of the slurry. The reselection effect of the test points was uated, and the static magnetic field was simulated and analyzed by AnsysMaxwell analysis software. When the permanent magnet is placed in each position of the dense-medium cyclone, the ash content of the clean coal and tail coal of each particle size is reduced in the static magnetic field compared with the absence of the magnetic field. When the permanent magnet is placed on the cylinder, there is no significant difference in the test results when the rotation direction of the permanent magnet is consistent with the rotation direction of the slurry and the opposite. When the permanent magnet rotates, compared with the static magnetic field, the ash content of each particle size is reduced. The ash content of the tailings of the particle size is increased; when the permanent magnet is located on the upper part of the cyclone cone, the specific position is that the permanent magnet is 80mm, 120mm, and 160mm away from the 太原理工大学硕士学位论文 IV barrel-cone interface. The test results are basically the same, and the rotation direction of the magnet is consistent with the rotation direction of the slurry. Compared with the static magnetic field, the ash content of the clean coal and tailings of each particle size are increased. When the rotating direction of the permanent magnet is opposite to the direction of slurry feeding, the ash content of each particle size of the cleaned coal is reduced, and the ash content of the tailing coal of each particle size is reduced compared with the static magnetic field. When the permanent magnet is located at the lower part of the cyclone cone, 240mm away from the cone-cone interface, when the magnet rotation direction is consistent with the pulp rotation direction, compared with the static magnetic field, the ash content of the clean coal and tailings of each particle size are increased. When the rotation direction of the permanent magnet is opposite to the rotation direction of the slurry, the ash content of the clean coal of each particle size is reduced compared with the static magnetic field, and the fluctuating change of the ash content of the tailings of each particle size is not much different from the ash content of the tailings under the static magnetic field; When the interface is 300mm, the test results when the rotating direction of the permanent magnet is the same and opposite to the rotating direction of the slurry are basically the same. When the permanent magnet rotates, compared with the static magnetic field, the ash content of the clean coal and tailings of each particle size are increased; when the permanent magnet When placed at the underflow port, there is no significant difference in the test results when the rotation direction of the permanent magnet is consistent with the rotation direction of the slurry and the test results are opposite. Compared with the rotation of the permanent magnet, the ash content of clean coal and tailings are both improved. From the uation results of the reselection effect, we can see δp non-magneticδp851δp-421δpstatic;Epnon-magneticEpstatic≈Ep851Ep-421.The separation density under static magnetic field is 0.09g/cm3 lower than that without magnetic field, Ep value is reduced by 0.0134 g/cm3, and the separation accuracy is improved; the rotation direction of the permanent magnet is consistent with the rotation direction of the pulp and the speed is 851 r/min, the separation density is 0.03g/cm3 higher than the separation density in static magnetic field, and the separation accuracy is basically unchanged; when the rotating direction of the permanent magnet is opposite to that of the pulp and the speed is 421 r/min. Compared with the static magnetic field, the separation density is increased by ABSTRACT V 0.012g/cm3, the Ep value is reduced by 0.0103 g/cm3, and the separation accuracy is greatly improved. Using AnsysMaxwell analysis software, it is initially revealed that the permanent magnet placed in the cone can reduce the separation density of the dense medium cyclone. The reason is that the oblique downward magnetic force attracts more magnetite powder to the bottom flow port and from the bottom flow port. Elimination thereby reducing the separation density of the dense medium cyclone. KeywordsDenseMediumCyclone;SeparationDensity;PermanentMagneticField;Rotat ion Speed;Magnetic Field Simulation 太原理工大学硕士学位论文 VI 目 录 I 目 录 摘 要............................................................................................................................ I ABSTRACT ................................................................................................................. III 第 1 章 绪论................................................................................................................ 1 1.1 研究背景及意义 ............................................................................................... 1 1.1.1 研究背景 .................................................................................................... 1 1.1.2 研究意义 .................................................................................................... 2 1.2 国内外研究现状 ............................................................................................... 2 1.2.1 传统重介质旋流器发展历程 .................................................................... 2 1.2.2 结构参数对重介质旋流器分选指标的影响 ............................................ 3 1.2.3 磁场对重介质旋流器的作用效果 ............................................................ 4 1.3 研究内容 ......................................................................................................... 11 第 2 章 试验系统的构建.......................................................................................... 13 2.1 试验系统的构建 ............................................................................................. 13 2.1.1 试验系统 .................................................................................................. 13 2.1.2 试验系统所用设备 .................................................................................. 14 2.2 煤样的性质 ..................................................................................................... 15 2.2.1 煤样粒度组成 .......................................................................................... 15 2.2.2 煤样密度组成 .......................................................................................... 16 2.2.3 重介质磁铁矿粉 ...................................................................................... 18 2.3 永磁铁 ............................................................................................................. 18 2.4 试验方法 ......................................................................................................... 19 2.4.1 粗煤泥分选试验 ...................................................................................... 19 2.4.2 重选效果评定试验 .................................................................................. 20 2.4.3 AnsysMaxwell 有限元分析 ..................................................................... 20 第 3 章 磁场模拟分析.............................................................................................. 21 3.1 AnsysMaxwell 有限元软件的介绍 ................................................................ 21 3.1.1 模型的建立 .............................................................................................. 21 3.1.2 材料管理 .................................................................................................. 21 3.1.3 边界条件以及激励源 .............................................................................. 21 太原理工大学硕士学位论文 II 3.1.4 网格剖分和求解器的设置 ...................................................................... 22 3.1.5 后处理 ...................................................................................................... 22 3.2 锥体上部磁场模拟 ......................................................................................... 22 3.2.1 锥体上部单磁极 3 片磁铁模型的确立 .................................................. 22 3.2.2 锥体上部单磁极 3 片磁铁的模拟结果 .................................................. 23 3.2.3 锥体上部单磁极 5 片磁铁模型的确立 .................................................. 26 3.2.4 锥体上部单磁极 5 片磁铁的模拟结果 .................................................. 26 3.3 锥体下部磁场模拟 ......................................................................................... 27 3.3.1 锥体下部单磁极 3 片磁铁模型的确立 .................................................. 27 3.3.2 锥体下部单磁极 3 片磁铁的模拟结果 .................................................. 27 3.4 底流口处磁场模拟 ......................................................................................... 29 3.4.1 底流口处单磁极 1 片磁铁模型的确立 .................................................. 29 3.4.2 底流口处单磁极 1 片磁铁的模拟结果 .................................................. 30 3.4.3 底流口处单磁极 3 片磁铁模型的确立 .................................................. 31 3.4.4 底流口处单磁极 3 片磁铁的模拟结果 .................................................. 32 3.5 筒体处磁场模拟 ............................................................................................. 33 第 4 章 锥部旋转磁场对重介质旋流器分选效果的影响...................................... 35 4.1 永磁铁距离筒锥交界面 80mm 处 ................................................................. 36 4.1.1 单磁极 1 片磁铁分选效果 ...................................................................... 36 4.1.2 单磁极 3 片磁铁分选效果 ...................................................................... 38 4.1.3 单磁极 5 片磁铁分选效果 ...................................................................... 40 4.2 永磁铁距离筒锥交界面 120mm 处 ............................................................... 41 4.3 永磁铁距离筒锥交界面 160mm 处 ............................................................... 43 4.4 永磁铁距离筒锥交界面 240mm 处 ............................................................... 45 4.5 永磁铁距离筒锥交界面 300mm 处 .............................................................. 47 4.5.1 单磁极 1 片磁铁分选效果 ...................................................................... 47 4.5.2 单磁极 3 片磁铁分选效果 ...................................................................... 50 4.6 重选效果评定 ................................................................................................. 52 4.6.1 试验条件 .................................................................................................. 52 4.6.2 浮沉试验 .................................................................................................. 52 目 录 III 4.7 本章小结 ......................................................................................................... 54 第 5 章 置于筒体及底流口处的旋转磁场对重介质旋流器分选效果影响.......... 57 5.1 永磁铁置于筒体处 ......................................................................................... 57 5.2 永磁铁置于底流口处 ................................................................