Continuous Separation of Inclusions from Aluminum Melt Flowing in a Circular Pipe using a High Frequency Magnetic Field

The continuous separation of inclusions from aluminum melt flowing in a circular pipe using a high frequency magnetic field was investigated both theoretically and experimentally. The separation efficiency was calculated based on the trajectory method and compared with experimental results. It is found that the separation efficiency is a function ofnondimensional parameters ti . The effective way to improve the separation efficiency is to increase the effective magnetic flux density and decrease the pipe radius, and the value of should be kept about 2 in order to obtain the optimum separation efficiency.

Separation of inclusions from aluminum melt using alternating electromagnetic field

Effects of processing variables such as frequency of imposed magnetic field, imposed magnetic flux density, processing time, diameter of inclusions, and value of r 1/δ on the electromagnetic separating(EMS) removal efficiency were analyzed theoretically. The higher the frequency, the wider the range of r 1/δ will be. Removal efficiency reaches the maximum while r 1/δ ranges from 1.5 to 2. And the experimental results on aluminum melt show that higher frequency and magnetic flux density make for higher removal efficiency, matching well with the theoretical results. When f is 15.6 kHz, B e is 0.1 T , and imposed time is 10 s, more than 80% inclusion particles with 6 μm diameter can be removed.

Separation efficiency of alumina particles in Al melt under high frequency magnetic field

The effects of separation time and magnetic induction intensity on the separation efficiency of alumina particles with diameters varying from 30 to 200 μm in aluminum melt were investigated. The experimental results show that the particle-accumulated layer is formed in the periphery of the solidified specimen when the diameter of the separated molten metal, the magnetic induction intensity and the separation time are 10 mm, 0.04 T and 1 s, respectively. When the separation time is 2 s, the particle-accumulated layer can be observed obviously and the separation efficiency is about 80%. There are few alumina particles in the inner of the solidified specimen when the separation time is 3 s. The separation efficiency higher than 85% can be achieved when the separation time is longer than 3 s. When the magnetic induction intensity is 0.06 T, the visible particle-accumulated layer can be formed in 1 s and the separation efficiency is higher than 95%. The experimental results were compared with the calculated results at last.

Continuous electromagnetic separation of inclusion from aluminum melt using alternating current

A novel scheme about the continuous electromagnetic purification of aluminum melt was put forward based on the utilization of a square separation pipe and a 50 Hz alternating current to produce electromagnetic force. It is experimentally found that with electrical current of 400 A/cm2, it takes only 10 s to remove 95% inclusion from aluminum melt. Comprehensive numerical simulations were carried out to investigate the dynamics mechanisms behind the process. The results show that the removal of inclusion is attributed to the cooperative effects of electromagnetic buoyancy and the secondary flow induced by the rotational electromagnetic force, and the removal efficient increases with the size of inclusion and the electrical current imposed. Theoretical predictions on the distribution and removal efficiency of inclusion were supported by the experiments.

Efficient Particle Separation in Microfluid Channel with Inhomogeneous Magnetic Field

In this paper, we combined magnetostatics and laminar flow in microfluidics and studied a particle separation scheme employing magnetophoretic force in inhomogeneous magnetic field. A detailed model and analysis is shown and the proposed scheme is capable of efficiently separating magnetic particles with different permeability and sizes. The method shows a way to separate efficient particles and could potentially be implemented in biological and chemical systems.

Effect of turbulent flow on electromagnetic elimination with high frequency magnetic field

The results of experiments and simulations show that there is a turbulent flow in the molten aluminum and it is hard to be restrained in the thin tubule (diameter of 6 mm) when the electromagnetic body force is applied. The electromagnetic elimination experimental results show that the flow has serious effect on the elimination of 5 μm alumina inclusions, but has little effect on the 30 μm and 100 μm primary silicon. The effects of the electromagnetic field and the turbulent flow on the electromagnetic elimination are discussed.

脉冲磁场去除钢中Al_(2)O_(3)夹杂物的研究

为了探究脉冲磁场对钢中Al_(2)O_(3)夹杂物的去除效果,使用中频感应炉进行了熔炼实验。利用COMSOL多物理场软件对脉冲磁场作用下钢液流场和不同尺寸夹杂物的去除行为进行了数值模拟,将数值模拟与实验结果相结合,探讨了脉冲磁场作用对钢中Al_(2)O_(3)夹杂物的去除机制。实验发现,施加脉冲磁场处理后,钢中Al_(2)O_(3)夹杂物整体含量减少,小尺寸的Al_(2)O_(3)夹杂物数量百分比降低,大尺寸的Al_(2)O_(3)夹杂物数量百分比有所增加,表明施加脉冲磁场促进了Al_(2)O_(3)夹杂物的去除和碰撞长大。数值模拟结果表明,施加脉冲磁场处理时,钢液中形成上下双环流,促进了夹杂物的去除,且夹杂物尺寸越大,去除效率越高;同时,夹杂物大部分被分离至壁面,与实验观察结果一致。

利用高频磁场分离Al熔体中的非金属夹杂

对利用高频磁场分离静置Ａｌ熔体中非金属夹杂的工艺参数进行了研究．通过理论解析计算得出频率ｆ，磁感应强度Ｂｅ，颗粒直径 ｄｐ，电磁力作用时间 ｔ，管径与集肤深度的比值ｒ１／δ等参数与夹杂分离效率 η的关系，并与实测分离效率进行了分析和比较实验结果表明，较高的磁场频率和磁感应强度是高分离效率的保证，对于粒径为 ６ μｍ的非金属夹杂，磁场频率为１５．６ ｋＨＺ，磁感应强度为 ０．１Ｔ时，电磁作用 １０ ｓ即可获得 ８０％以上的夹杂分离效率；ｒ１／δ值的影响与频率有关，频率越高，则ｒ１／δ的取值范围越宽；ｒ１／δ＝１．５－２时可使分离效率获得最大值．

行波磁场净化液态金属时矩形管及三角形管内夹杂物去除效率的理论解析

采用活塞流及轨线模型，对行波磁场净化液态金属时，三角形及矩形管中夹杂物的去除效率进行了理论分析，找出了提高夹杂物去除效率的途径；对两种形状管的夹杂物去除效率进行了比较；

影响铝熔体电磁净化效果因素的分析

从液态金属电磁净化技术的原理出发,在理论上分析了当夹杂物与金属熔体密度接近的情况下,可以利用两者之间的电性能与磁性能的差异来实现夹杂物的分离,达到金属熔体净化的效果.综述了影响电磁分离效率和效果的因素.表明在电磁净化过程中,通电时间越长、磁感应强度越大、管半径与集肤程度比值在1.5～2.0之间、分离管为异型管、夹杂颗粒越大且近于球形,分离效果越理想,分离效率越高.

对含有Al_2O_3的铝熔体电磁分离实验研究

通过向Al熔体中加入SiO2颗粒,成功制备了Al-10%Al2O3复合材料;并采用远大于集肤层厚度的直径30mm陶瓷分离管和中空管进行了分离实验.结果表明大尺寸分离管同样能实现电磁净化,只是分离时间比中空管略长,可能是因电磁搅拌效应引起的流动造成的.对含有30～200μm Al2O3颗粒的铝熔体的电磁连续净化实验结果显示:仅使用泡沫陶瓷过滤该合金时,平均净化效率为96.15%;当施加0.06T的高频磁场时,复合过滤净化效率的平均值为97.30%,比泡沫陶瓷单独净化的效率高了1.15%.对Al-10%Mg合金的连续净化实验结果表明,仅用泡沫陶瓷过滤该合金时,经过两次过滤后可将合金中的氧含量从0.000 9%降低为0.000 4%,净化效率为55.6%;而当泡沫陶瓷外加0.04T磁场复合净化时,氧含量从0.001 4%降低为0.000 3%,净化效率达到78.6%.

铝熔体中金属杂质颗粒在稳恒磁场中的运动状态

对稳恒磁场中的金属杂质颗粒进行了受力分析,建立了杂质颗粒的运动模型,经过理论计算确定了它们在磁场力的作用下,处于不同流场内的最终运动速度·根据铝熔体的不同的流动状态,分别采用柱塞流模型和轨线模型计算得出了磁场力对杂质颗粒的分离效率·计算结果表明,杂质的运动速度与分离效率和自身的体积、流体的流动状态、杂质颗粒的磁化率、磁场强度及分离通道的宽度密切相关·在相同的熔体流动速度下,杂质颗粒越大,分离效率越高;降低流体的流动速度有利于提高分离效率·

高频磁场下铝合金中非金属夹杂物电磁分离研究

在高频磁场作用下,利用金属与夹杂物之间电导率差产生的电磁排斥力去除非金属夹杂物.实验材料为Al-10%Al2O3、Al-10%SiC及Al-24%Si.将含有杂质的合金置于不同管径的分离器中,开启高频电源,调整输出功率,利用高频磁场将其熔化,并进一步实现非金属夹杂物的分离.分析了不同管径、颗粒尺寸、磁感应强度、作用时间等条件下的分离效果,结果发现球形Al2O3和SiC颗粒较针状初生硅的分离效果好一些,较高的磁感应强度和小的管径对夹杂物的分离有利.

环形六孔纳米磁珠分离器设计与试验

免疫磁珠分离技术在生物检测中的应用日益广泛,能提供高强度大梯度磁场环境的纳米磁珠分离器是免疫磁珠分离技术中的关键技术之一。设计了一种新颖的环形六孔纳米磁珠分离器,通过瓦状钕铁硼磁块的优化布局和斜壁坡莫合金导磁片设计,实现了在同一台纳米磁珠分离器上形成6个强磁场高梯度分离区域（分离孔）,分离器最高磁场强度达1.44 T,最高磁场梯度达96.3 T/m（体积865.5 cm3,质量4.8 kg）,同一分离器内6个分离孔内磁场分布相同,孔间平均相对偏差在2.0%~3.3%之间。对磁分离孔磁场分布的测试和仿真结果表明：磁珠分离器体积、导磁片材料和导磁片形状等因素对磁珠分离器磁场强度和梯度有不同程度的影响,采用大体积磁块的磁珠分离器比采用小体积磁块的磁珠分离器、采用坡莫合金作为导磁片比采用软铁材料作为导磁片、采用斜壁形状的导磁片比采用直壁形状的导磁片均能实现较大的磁场强度和梯度。该纳米磁珠分离器已成功应用于大肠杆菌和禽流感病毒的免疫磁分离试验研究,并可以根据不同应用需求,组合相关要素以获得理想的免疫磁珠分离器。

连续分离铝熔体中夹杂物的分析

通过分析高频磁场作用下熔体连续处理时夹杂的去除效率表明,熔体连续处理条件下的夹杂去除效率比熔体静止时的略低,而夹杂与熔体之间的密度差对电磁分离时的去除效率影响不大。提高去除效率的有效途径是增大磁感应强度或降低分离器管径,但减小管径的同时需要提高磁场频率,以保持α/δ的值在2附近才可以取得最佳的分离效果。

利用旋转磁场去除铝熔体中的夹杂物颗粒

研究了旋转磁场去除液态铝合金熔体中夹杂物颗粒的效果。将铝硅过共晶合金凝固过程中析出的初生硅颗粒视为夹杂物颗粒。采用旋转磁场,研究了密度比周围铝熔体密度大的初生硅夹杂物颗粒在旋转磁场下的分布规律。利用光学显微镜和数码相机对凝固试样的宏观及微观组织进行观察。实验结果表明:旋转磁场可以有效去除液态铝合金熔体中的夹杂物颗粒,并且旋转磁场的除杂效果随着磁场频率的增大而显著增加。因此旋转磁场提供了一种高效的金属熔体净化的方法。

电磁作用下铝熔体中产生涡流的影响因素

在电磁分离铝熔体杂质的过程中易产生涡流·涡流的产生会降低分离杂质效果·为了抑制涡流 ,提高杂质分离效果 ,在不同磁感应强度 ,不同的分离器与磁场相对位置 ,不同感生电流密度等条件下进行实验 ,观测铝熔体表面状态·实验结果表明 ,铝熔体中产生的涡流随磁场强度增大而剧烈 ;随铝熔体表面与磁极表面垂直距离的减小而增强 ;

500 kA铝电解槽的磁场分布与电流效率

对500 k A铝电解槽的磁场强度和电流效率开展测试和研究,重点分析垂直方向磁场大小对电流效率的影响并提出应对技术措施。

高频磁场下熔体夹杂迁移行为的研究

本文研究了高频磁场中熔体夹杂的迁移行为,利用感应线圈产生的高频磁场,选取Al-2%Fe、Al-5%Fe合金中的产生的富铁相作为研究对象。颗粒与熔体之间的导电率存在很大的差异,当外加磁场时,产生的电磁力作用于熔体,固相颗粒将向分离器外壁面迁移而除去。通过加入变质剂Mn元素研究其对富铁相形貌的影响,研究表明:在Mn/Fe的摩尔比为1.4～1.5时,针状的富铁相变成了块状或汉字状,减小富铁相再熔体中迁移受到的阻力,使之更利于在熔体中迁移,并进一步探讨了电磁分离过程中各工艺参数对夹杂颗粒迁移行为和实际分离效率的影响。

铜合金中氧化物夹杂的电磁分离

通过向Cu-10Sn合金中加入1%的Cu2O颗粒制备了含有SnxOy合金的材料,随后利用高频磁场的电磁分离技术成功将铜合金中的氧化物夹杂分离到分离器边缘。研究了分离器直径、磁感应强度、分离时间对分离效果的影响。试验结果表明,当分离器直径为12mm,磁感应强度为60mT,分离时间为60s时,氧化物夹杂的分离效果最好。