Continuous separation of Fe–Al–Zn dross phase from hot dip galvanised melt using alternating magnetic field

Abstract

Experiments to continuously separate Fe–Al–Zn dross phase from hot dip galvanising zinc melt were conducted on a laboratory scale apparatus by using high frequency alternating magnetic field. Effects of processing time (t) on separation efficiency were investigated. The experimental results show that using the electromagnetic repulsive force resulting from the electrical conductivity difference between zinc melt and Fe–Al–Zn dross phase, the deleterious zinc dross particles causing surface defects of galvanising steel sheets can be continuously separated from the zinc bath under alternating magnetic field, and the separation efficiency increases with the increase in processing time. When the magnetic frequency is 17·5 kHz, the effective magnetic flux intensity is 0·1 T, the cross-section of the ceramic square pipe is 10 × 10 mm, and the processing time is 0·6–2·5 s, the separation efficiency of zinc dross varies from 43·76 to 85·71%, and the experimental results are in reasonable agreement with the theoretical results.     

超导磁分离工业废水处理技术研究

超导高梯度磁分离污水处理是一种新型的污水处理技术.采用超导磁体和经过表面有机改性的铁磁性颗粒为"磁种"与污水中非磁性有害物质絮接,通过强磁场分离COD值降到78 ms/L,污水净化效果良好.讨论了利用等离子体聚合薄膜制备具有强捕捉能力的磁性粒子工艺.     

Exploring ways to improve efficiency of gasdynamic energy separation

This work is devoted to research into ways to improve the efficiency of gasdynamic energy separation in the pipe Leontiev. It is shown that restoring the coefficient of temperature r depending on the Prandtl number Pr has the greatest impact on the magnitude of energy separation. The conducted analysis showed that for a gas with Pr = 0.7 the most promising ways to improve the efficiency of gasdynamic energy separation are the partial condensation of the working body and the use of regular relief that is deposited onto the wall of the supersonic channel in the pipe Leontiev. We have performed a modification of the calculation method and its verification using experimental data obtained on natural gas. The results of numerical modeling have shown that the use of regular relief (dimples) in this class of devices is effective.     

Gas-solid separation performance and structure optimization in 3D printed guide vane cyclone separator

Low separation efficiency and large pressure drop are two common problems of cyclones. In this paper, a 3D printed guide vane cyclone separator was designed to study the separation efficiency, turbulent kinetic energy, and particle movement of particle group by experiment and simulation. The results shown that the tangential velocity was the major influence of separating. The bottom of the exhaust pipe was the main region of gas–solid separation and pressure drop. The separation efficiency and pressure drop were positively correlated with the inlet velocity and the particle radius of the fluid. The distribution of turbulent kinetic energy that leaded to the pressure drop loss was concentrated on the inlet of the exhaust pipe. The swirl has external and internal two directions. The optimized cyclone has a longer and narrower blade flow path to obtain higher separation efficiency, especially at low inlet velocity.     

Effect of particle-wall interaction on triboelectric separation of fine particles in a turbulent flow

Triboelectric separation is an effective way to separate fine powders with particle sizes and densities in the same order of magnitude. Many relevant process variables influence the charging behaviour; however, the corresponding effects on the subsequent separation of particles remain unknown. To utilize triboelectric separation as a powerful tool for fine powder separation, process parameters such as the choice of contact wall materials in the charging region have to be investigated. We report for the first time the influence of the tube’s wall material, in which particle charging took place, on triboelectric separation of fine protein-starch mixtures. Different electrically insulating materials along the triboelectric series were tested. No significant influence of the wall material on the separation selectivity and efficiency was found. In addition, particle-wall interaction was inhibited using an experimental setup which allows to control the flow boundary-layer by blowing out air through the tube wall. Also the results obtained by this novel setup showed no significant differences compared to the setup with particle-wall interactions. Additionally, CFD simulations were used to confirm the absence of particle-wall interactions in the boundary-layer control setup. A variation of the boundary-layer thickness leads to a constriction of the particle-containing flow region in the centre of the pipe. Experiments show that this compression of the particle flow zone results in no further increase in selectivity and efficiency of separation. Thus, particle-particle interaction is the prevalent triboelectric charging mechanism of fine powders charged in a turbulent flow regime.     

The Study of Performance in a Novel Gas–Solid Separator

The three slit-type separator is a new separator which can shorten the residence time of oil & gas and improve the separation efficiency. In this study, a critical validation was carried out to examine the separation performances of the three slit-type separator with different inlet velocity and inlet concentration. According to the experimental results, the separation efficiency and pressure drop of the three slit-type separator increase with the increase of inlet velocity and inlet concentration. Numerical simulation of the gas–solid flow field in the three slit-type separator was carried out by the use of Fluent 15.0 platform. The simulated results coincide with the experimental results. The particles move along the inside wall of the separator in the vaulted space, meanwhile, more gas enters into the exhaust pipe through slots, which can improve the separation efficiency. The study shows that the residence time of oil and gas is less than 0.6 and the separation efficiency is up to 99% in the separator, in addition, the pressure drop could be controlled in 4 kPa below.     

Rapid magnetophoretic separation of microalgae

Magnetic collection of the microalgae Chlorella sp. from culture media facilitated by low-gradient magnetophoretic separation is achieved in real time. A removal efficiency as high as 99% is accomplished by binding of iron oxide nanoparticles (NPs) to microalgal cells in the presence of the cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA) as a binder and subsequently subjecting the mixture to a NdFeB permanent magnet with surface magnetic field ≈6000 G and magnetic field gradient <80 T m(-1) . Surface functionalization of magnetic NPs with PDDA before exposure to Chlorella sp. is proven to be more effective in promoting higher magnetophoretic removal efficiency than the conventional procedure, in which premixing of microalgal cells with binder is carried out before the addition of NPs. Rodlike NPs are a superior candidate for enhancing the magnetophoretic separation compared to spherical NPs due to their stable magnetic moment that originates from shape anisotropy and the tendency to form large NP aggregates. Cell chaining is observed for nanorod-tagged Chlorella sp. which eventually fosters the formation of elongated cell clusters.     

Spatial fractionation of paramagnetic particles precipitating in a high-gradient magnetic field of a short magnetized cylinder

The motion of dia- and paramagnetic particles precipitating in a liquid near a vertical magnetized cylinder of finite length in a plane transverse to the direction of magnetization has been studied, the phenomenon of spatial separation of paramagnetic particles by the value of magnetic susceptibility is described, and a comparison of the efficiency of separation of paramagnetic particles in the fields of a short cylinder and a sphere has been carried out.     

Size effects of magnetic beads in circulating tumour cells magnetic capture based on streptavidin–biotin complexation

Circulating tumour cells (CTCs) draw significant attention as a promising biomarker for cancer prognosis, status monitoring, and metastasis diagnosis. However, the concentration of CTCs in peripheral blood is usually extremely low, thereby requiring enrichment followed by isolation of CTCs prior to detection. An immunomagnetic separation is a promising tool for CTCs enrichment. In this study, a cost‐effective magnetic separation method, based on streptavidin–biotin complexation, was developed and the effects of magnetic beads’ size in CTCs capture were compared. Magnetic nanobeads which were 25 nm in diameter lead to highest capture efficiency (82.2%) compared with 150 nm magnetic beads and 1 µm microbeads. Based on the streptavidin–biotin system, 25 nm magnetic nanobeads could capture model CTCs over 80% efficiency even at concentrations as low as ∼25 cells/mL that may represent the actual level of CTCs in peripheral blood of cancer patients. Furthermore, the isolated cells remained robust and healthy showing insignificant changes in morphology and behaviour when cultured for 24 h immediately after capture and isolation. The magnetic nanobeads based on streptavidin–biotin complexation showed promise for the easy and efficient capture and isolation of healthy CTCs for further diagnosis and analysis.Inspec keywords: cancer, magnetic separation, nanomedicine, nanomagnetics, proteins, biomagnetism, tumours, cellular biophysics, magnetic particles, molecular biophysics, blood, nanoparticlesOther keywords: streptavidin–biotin complexation, cancer prognosis, peripheral blood, immunomagnetic separation, CTCs capture, streptavidin–biotin system, circulating tumour cells, CTC enrichment, magnetic separation method, magnetic nanobeads, magnetic capture, size 25.0 nm, size 150.0 nm, time 24.0 hour     

宝钢60000m~3/h空分设备污氮管网分析计算

应用可压缩流体管网分析软件AFTARROW,对宝钢60000m~3/h空分设备的污氮管网进行了分析计算,得出了污氮管网总的压力损失及其分布情况,并提出了改进措施,为以后空分设备的污氮管网设计提供了依据。     

Bacterial inactivation using silver-coated magnetic nanoparticles as functional antimicrobial agents

The ability for silver nanoparticles to function as an antibacterial agent while being separable from the target fluids is important for bacterial inactivation in biological fluids. This report describes the analysis of the antimicrobial activities of silver-coated magnetic nanoparticles synthesized by wet chemical methods. The bacterial inactivation of several types of bacteria was analyzed, including Gram-positive bacteria ( Staphylococcus aureus and Bacillus cereus ) and Gram-negative bacteria ( Pseudomonas aeruginosa , Enterobacter cloacae , and Escherichia coli ). The results have demonstrated the viability of the silver-coated magnetic nanoparticles for achieving effective bacterial inactivation efficiency comparable to and better than that of silver nanoparticles conventionally used. The bacteria inactivation efficiency of our silver-coated MnZn ferrite (MZF@Ag) nanoparticles was also determined for blood platelets samples, demonstrating the potential of utilization in inactivating bacterial growth in platelets prior to transfusion to ensure blood product safety, which also has important implications for enabling the capability of effective separation, delivery, and targeting of the antibacterial agents.     

Finite element method in magnetohydrodynamic channel flow problems

The finite element method has been applied to the steady-state fully developed magnetohydrodynamic channel flow of a conducting fluid in the presence of transverse magnetic field. Simple elements have been used to obtain the numerical values of velocity and induced magnetic field. To test the efficiency of the method, three different geometries, viz., rectangle, circle and triangle, are taken as the section of the pipe whose walls are non-conducting. Comparison is made with those cases in which exact solutions are available. Apart from giving good results, the FEM makes it possible to solve the problem for a pipe with arbitrary cross-section which was not possible by the other methods.     

Effect of the Magnetic Dipole–Dipole Interaction on the Capture Efficiency in Open Gradient Magnetic Separation

In magnetic separation, the magnetic dipole-dipole (DD) interaction between particles has an important effect on the capture efficiency. By producing transient particle agglomerations, this interaction can considerably speed up the separation process. To take into account adequately this effect in ferromagnetic particle random dispersion, we have developed a modeling approach. The approach is based on the coupling of the magnetic force equation and a local homogenizing model for the material magnetic permeability. To verify the efficiency of the proposed approach on one hand and to estimate the effect of the DD interaction on the particle capture on the other hand, we consider a problem of open gradient magnetic separation (OGMS). We also conducted a limited experimental verification of the transient agglomeration for fine ferromagnetic particles.     

多联机旋风式油气分离器内管与进气碰撞的数值模拟

以小型多联机用旋风式油气分离器为研究对象,建立三维稳态数值模型。气流场选用重整化群湍流模型(RNGk-ε),油滴轨迹采用随机轨道(DRW)模型,研究内管长度、筒体高度和进气碰撞程度对油气分离器内部流场分布、分离效率和压降的影响。发现大部分油滴在内管截面以上的筒体空间内完成分离;油气分离器所需内管长度与筒体高度比值随进气速度的增加而减小;进气碰撞程度(油气分离器横截面上内管下边缘与进气管上边壁的垂直距离与进气管径的比值,即h1/di)小于26.57%,进气速度大于23.09 m/s时,更容易获得稳定的旋流流场。     

空分设备产能的合理利用

针对武钢氧气公司空分设备氮气压缩能力不足、无法有效满足内部用户用氮需求的问题,采用合理利用空分设备放散的氮气,并将各空分设备和氮压站的氮气管网连通的改进措施,将空分设备的氮气产能充分利用,减少空分设备的运行时间,满足内部用户的用气需求,取得了节能降耗的效果。     

High gradient magnetic particle separation in viscous flows by 3D BEM

The boundary element method was applied to study the motion of magnetic particles in fluid flow under the action of external nonuniform magnetic field. The derived formulation combines the velocity-vorticity resolved Navier–Stokes equations with the Lagrange based particle tracking model, where the one-way coupling with fluid phase was considered. The derived algorithm was used to test a possible design of high gradient magnetic separation in a narrow channel by computing particles trajectories in channel flow under the influence of hydrodynamic and magnetic forces. Magnetic field gradient was obtained by magnetization wires placed outside of the channel. Simulations with varying external magnetic field and flow rate were preformed in order to asses the collection efficiency of the proposed device. We found that the collection efficiency decreases linearly with increasing flow rate. Also, the collection efficiency was found to increase with magnetic field strength only up a saturation point. Furthermore, we found that high collection efficiently is not feasible at high flow velocity and/or at weak magnetic field. Recommendation for optimal choice of external magnetic field and flow rate is discussed.     

油气输运管道缺陷漏磁检测量化技术研究

通过实测得到油气输运管道缺陷漏磁(MFL)信号，分析了缺陷几何尺寸与信号特征量之间关系。采用特征提取和模式识别技术对缺陷进行量化分析。对缺陷的长、宽、深三个指标分别应用不同的特征量和相应的非线性方法进行定量识别。试验结果表明，缺陷长度、宽度和深度的预测准确度分别达到了100％、89％和77．8％。这里通过使用长宽比特征量描述方法，有效地提高了深度的估计精度，很好地解决了管道缺陷的量化识别问题。     

Hydromagnetic convection flow through a porous medium in axially varying pipe

The hydromagnetic mixed convection flow through a porous medium in a pipe of varying radius in a uniform axial magnetic field is analyzed. The pipe wall is maintained at a prescribed nonuniform temperature. The governing equations are solved analytically to obtain the velocity, temperature, and induced magnetic field. Their behaviors are evaluated for different variations in the governing parameters. __________ Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 79, No. 4, pp. 96–104, July–August, 2006.     

Ballast water treatment technologies: hydrocyclonic a viable option

Many governments, international maritime environmental entities and public health organizations have recognized the environmental, economic and health threats caused by the translocation and release of ballast water. A wide variety of ballast water treatment systems are available at both commercial and under evaluation levels. The available ballast water treatment technologies are reviewed. This work reviews the various types of technologies used in treating ballast water and special attention is given to hydrocyclonic system. Small scale pilot plant hydrocyclone was investigated to identify the behaviour of solid particle separation under the effect of alum addition during the separation. The addition of alum gave a clear improvement on the particle separation but still the use of such a chemical is questionable due to the environmental impact and quantity and time to get effective separation. For particle size greater than 0.8 mm, the removal efficiency ranges from 70 to 86% without alum and from 73 to 90% with alum. The improvement in the removal efficiency is estimated around an average of 4% only. Whereas, for particle size less than 0.3 mm, the removal efficiency ranges from 16.5 to 57% without alum and from 27 to 75% with alum. The addition of alum gave around an average of 15% improvement in the removal efficiency. This concludes that the addition of alum has greater impact on the removal efficiency for particle sizes less than 0.3 mm and less impact on greater particle sizes.     

Microfluidic-Assisted CTC Isolation and In Situ Monitoring Using Smart Magnetic Microgels

Capturing rare disease-associated biomarkers from body fluids can offer an early-stage diagnosis of different cancers. Circulating tumor cells (CTCs) are one of the major cancer biomarkers that provide insightful information about the cancer metastasis prognosis and disease progression. The most common clinical solutions for quantifying CTCs rely on the immunomagnetic separation of cells in whole blood. Microfluidic systems that perform magnetic particle separation have reported promising outcomes in this context, however, most of them suffer from limited efficiency due to the low magnetic force generated which is insufficient to trap cells in a defined position within microchannels. In this work, a novel method for making soft micromagnet patterns with optimized geometry and magnetic material is introduced. This technology is integrated into a bilayer microfluidic chip to localize an external magnetic field, consequently enhancing the capture efficiency (CE) of cancer cells labeled with the magnetic nano/hybrid microgels that are developed in the previous work. A combined numerical-experimental strategy is implemented to design the microfluidic device and optimize the capturing efficiency and to maximize the throughput. The proposed design enables high CE and purity of target cells and real-time time on-chip monitoring of their behavior. The strategy introduced in this paper offers a simple and low-cost yet robust opportunity for early-stage diagnosis and monitoring of cancer-associated biomarkers.