In addition to engineering applications, magnetic fluids containing magnetic nanoparticlesare being increasingly applied to biomedical purposes. Besides the well establisheduse of magnetic particles for biological separation or as contrast agents for magneticresonance imaging, magnetic particles are also being tested for the inductive heat treatmentof tumors or as markers for the quantification of biologically active substances.The properties of magnetic nanoparticles usually exhibit a broad distribution, so inmany cases upon application only a small fraction of the particles contribute fully to thedesired magnetic effect. Therefore, magnetic fluids have to be optimized by fractionationtechniques. This is preferentially achieved by methods that separate magnetic nanoparticlesin accordance with their magnetic properties. Hence, a magnetic technique hasbeen developed for the fractionation of magnetic fluids. Two different magnetic fluidswere fractionated by this method. The fractions obtained and the original samples werecharacterized with respect to their magnetic properties as well as their particle sizes. Theywere investigated not only in terms of their magnetization curves but also in respect tobiomedical applications. The magnetic fractions show clearly improved magnetic propertiescompared to the original samples and are therefore especially suited for distinctapplications. Furthermore, the results indicate that the magnetic method fractionates theparticles in accordance with their magnetic moment and has a good reproducibility.

Thomas  Rheinl&#228;nder

R&#243;man  K&#246;titz

Werner  Weitschies

Wolfhard  Semmler

Magnetic Fluids: Biomedical Applications and Magnetic Fractionation

In this study, a superconducting high gradient magnetic separator (HGMS) with amatrix vibration system in dry mode was utilised to purify fine calcite and quartzpowders smaller than 38 &#181;m. The effects of the operating parameters (particle size,magnetic field&#47;average air velocity (Bo &#47;Vo), the amplitude of vibration as well as the aperture size of the expanded metal matrix) have been presented. The mechanicallybased matrix vibration with the air blowing was recognised to be effective for drypurification of fine powdered materials at high magnetic fields. The function of thematrix vibration has been discussed. In addition, the results have been empiricallycorrelated with the operating parameters used for the purification in the separator.

Yanmin  Wang

Ann-Cathrine  Johansson

Eric  Forssberg

Billy  Chan

Purification of Fine Powders by a Superconducting HGMS With Vibration Assistance

The separation principle and the advantage of using magnetic polymer particles inbioseparation is elucidated. After a short review of the presently used diverse magneticmicroparticles as well as the basic differences of micro- and nanosized magnetic particleswith regards to their physical properties in bio-separation, preparation and applicationof novel magnetic microparticles prepared from polyvinylalcohol are described. Theperformance of the novel product and their superior properties over established productsin diverse bioseparation tests are shown. Furthermore, nanoparticles used for a newAIDS therapy approach are described. The basic principle is explained by which theAIDS virus (HIV) is destroyed through heat generated by inductively heated magneticnanoparticles, which are specifically attached to the virus. Inductive heating tests withmodel magnetic colloids show that the required temperatures of &#62; 50&#176;C can easily beachieved.

Detlef  M&#252;ller-Schulte

Novel Magnetic Microand Nanoparticles for Biomedical Separation and as Means for a New Approach to Aids Therapy

Jan Svoboda

Book Review

The fine ilmenite material finer than 0.045mm at the Pang Zhi Hua Ilmenite Processing
Plant was discarded for the lack of efficient processing equipment and method. The total
recovery of ilmenite in the plant had been only about 17-20%. To increase the ilmenite
recovery, numerous laboratory, pilot and commercial tests were conducted in 1995-1996.
Finally, a magnetic separation-flotation flowsheet was chosen for the commercial test, in
which the fine fraction was fed into 125 mm diameter cyclones for desliming. The underflow
of the cyclones was then fed into the magnetic separation-flotation flowsheet. A SLon-
1500 vertical ring and pulsating high gradient magnetic separator was applied as a rougher
and was followed by flotation as a cleaner. The overall results of the magnetic separationflotation
flowsheet in the commercial test were: feed 11.03% TiO2, concentrate 47.36%
TiO2, recovery 44.79% TiO2. The flowsheet of the commercial test has been used as a production process since 1997. The recovery accounted for about 12% TiO2 of the feed
into the ilmenite processing plant.

Xiong Da-He

Research and Commercialisation of Treatment of Fine Ilmenite With Slon Magnetic Separators

A novel benefit of an ordered High Gradient Magnetic Separation (HGMS) matrix, madeup of parallel ferromagnetic wires is presented. One shows that the magnetic force Fmdepends on &#945;, the angle between the wires of the matrix and the applied magnetic field H0 .There is a relation between the tilting angles and magnetic susceptibilities of particlespulled out from the mixture. This relation proves a practical possibility of separating amixture only by choosing adequate tilting angles; the method is named separation inangular steps. Finally one shows two applications based on this principle: a separatorwhich extracts successively and another one which extracts concomitantly differentmagnetic fractions from a granular mixture.

Gh.  Iacob

N.  Rezlescu

A Novel Advantage of HGMS Ordered Matrices

Separability and separation mechanisms of small particles in modern rotating type eddycurrentseparators (ECSs) were discussed in Part I. In order to address problems associatedwith this design concept, a number of novel ECSs, each with a unique design, havebeen developed. Part II reports on investigation into the separability and separation principlesfor various materials smaller than 5 mm, including fine copper wires, in three newdevices: the redesigned Delft vortical ECS (VECS), prototype TNO ECS and a laboratorywet ECS (WECS). It is found that TNO ECS and WECS are more practical tools forseparation of small metal particles. In particular, WECS is able to recover approximately80% of very fine copper wires, with 0.5mm diameter and 2mm length. Separation principlesfor WECS are discussed in greater detail than other design concepts in the presentstudy. It appears that the fledgling WECS will be most promising in the future for proccssingsmall particles. Further, aluminum separation from the &#8212;10 mm fraction of electronicscrap has been carried out using TNO ECS. It transpires that both the recovery andthe grade of the aluminum concentrate are superior to those obtained with the rotarybolted-drum ECS of any type.

Peter C. Rem

Shunli  Zhang

Tako P. R. de Jong

The Investigation of Separability of Particles Smaller Than 5mm by Eddy-Current Separation Technology &#8211;  Part II: Novel Design Concepts

Using two models, namely the initial differential equation of motion and the reduced equationobtained from the initial one by neglecting the inertial force comparative calculationsof the capture cross section of paramagnetic particles by a cylindrical ferromagneticcollector (a wire) were carried out. For various combinations of the particle diameter, thewire diameter, medium flow velocity, strength of the magnetic field, the error in the capturecross section caused by neglecting the inertial force in the equations of motion was determined.Approximate formulae for the determination of this error and of the ratio of theinertial force to the magnetic force as a function of the main separation parameters wereproposed.

Yu. S. Mostika

V. I. Karmazin

V. Yu. Shutov

L. Z. Grebenyuk

The Assessment of the Applicability of a Model of Noninertial Motion of a Particle in a Magnetic Separator

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Physical Separation in Science and Engineering - Table of contents 2000

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Physical Separation in Science and Engineering