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Magnetics, IEEE Transactions on

Issue 5 • Date September 1976

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  • [Front cover and table of contents]

    Publication Year: 1976 , Page(s): 0
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  • Message from the president of the IEEE magnetics society

    Publication Year: 1976 , Page(s): 423
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  • Introduction to the proceedings of magnetic desulfurization of coal symposium

    Publication Year: 1976 , Page(s): 424
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  • Organization of magnetic desulfurization of coal symposium

    Publication Year: 1976 , Page(s): 425
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  • Highlights of the symposium

    Publication Year: 1976 , Page(s): 426 - 427
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  • High gradient magnetic separation theory and applications

    Publication Year: 1976 , Page(s): 428 - 435
    Cited by:  Papers (9)  |  Patents (14)
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    This paper discusses key technical and economical achievements which have extended the range of application of magnetic separation methods into the commercial processing of micron size feebly magnetic materials. Commercial application of magnetic methods in the cleaning of kaolin clay is reviewed and a discussion of magnetic separation principles is given with emphasis on identification and utilization of important process parameters. Possible future developments in magnetic processing of municipal and industrial wastewaters and of applications of magnetic methods to the preparation of clean fuels from coal are discussed. View full abstract»

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  • New developments in magnetic separation

    Publication Year: 1976 , Page(s): 436 - 443
    Cited by:  Papers (6)
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    High extraction magnetic filters combine high gradient features of the Frantz FerrofilterR, high intensity concepts of the Jones separators, and principles of modern magnet design derived from high energy physics research. Evolution of high extraction magnetic filters used commercially by all major kaolin producers is reviewed and new trends in equipment are highlighted. View full abstract»

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  • Engineering development of high gradient magnetic separators

    Publication Year: 1976 , Page(s): 444 - 449
    Cited by:  Papers (3)
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    The commercial development of high gradient magnetic separation began in 1969 when the first industrial, cyclic high gradient magnetic separators were sold to the J.M. Huber Corporation by Magnetic Engineering Associates, Sala's predecessor, for processing high grade paper coating clays. Since that time, high gradient magnetic separation for the processing of high quality clays has come to be fully accepted in the United States kaolin industry. A number of large cyclic separators of the Sala design, with capacity ratings above 60 tph have been constructed under license from Sala and installed in major U.S. clay producers' facilities. Applications of high gradient magnetic separation technology to mineral processing and water treatment have been explored(1,2,3,4). The cyclic high gradient magnetic separators utilized in the clay industry may be employed for most water treatment applications since the volume of magnetic material to be removed is a relatively small percentage of the total flow volume through the machine. In the majority of mineral separation and beneficiation problems, the feed percentage of magnetics is more than 1 to 2 percent and to solve this problem efficiently a continuous high gradient magnetic separator has been developed by us. A 15 tph continuous pilot separator is now operating in our Cambridge pilot plant and is able to process ores with the effectiveness of the cyclic high gradient magnetic separators. View full abstract»

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  • Research needs in magnetic separation

    Publication Year: 1976 , Page(s): 450 - 454
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    High gradient magnetic separation is a new technique which provides a practical means for separating weakly paramagnetic materials down to colloidal particle size on a large scale and at flow rates one hundred times faster than conventional filtration. It is based on the use of matrices of finely divided filamentary ferromagnetic material containing 95% void space, such as steel wool, subjected to strong magnetic fields generated bysophisticated magnets of a type not previously used for magnetic separation. HGMS was developed in the late sixties by MIT, Sala Magnetics and the Huber Company, and has been used since then for the purification of kaolin. The technique is of importance to the entire chemical and mineral industry, and in the treatment of water and sewage, but its application in other areas has been delayed by lack of interdisciplinary communication. What is needed at present is a better understanding of the mechanism of HGMS to permit a more scientific approach to future applications, and more inducement to the firms which are currently developing the next generation of hardware. Other approaches to magnetic separation also merit more serious attention, particularly those based on open gradient rather than matrix structures. New magnet technology developed in conjunction with HGMS and the advent of superconductivity make available field strengths, gradients and volumes at least an order of magnitude above those offered by the prior art. Such magnetic fields have potential value beyond their use in magnetic separation inasmuch as they are likely to affect the kinetics of many chemical reactions, very probably also those involved in the combustion process itself. View full abstract»

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  • Magnetic separation of the second kind: Magnetogravimetric, magnetohydrostatic, and magnetohydrodynamic separations

    Publication Year: 1976 , Page(s): 455 - 462
    Cited by:  Papers (7)  |  Patents (2)
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    Magnetogravimetric, magnetohydrostatic, and magnetohydrodynamic separation techniques can be classified as magnetic separations of the second kind. Magnetic separation of the first kind (ordinary magnetic separation) relies on the inherent magnetic susceptibility of the material to be separated. When the medium of separation rather than the separated particles is made magnetizable, a new system of gravity separations can result (magnetic separation of the second kind). In magnetogravimetry, a colloidal solution of a ferro- or ferrimagnetic substance (magnetic fluid) acts as the separation medium. Magnetohydrostatic separations are conducted in an aqueous solution (or melt) of a strongly paramagnetic salt. Magnetohydrodynamics applies the Faraday effect (mutual orthogonality of the force thrust, electric, and magnetic fields) on suspended conducting minerals in an electrolytic solution placed in crossed electric and magnetic fields. The first technique was pioneered mainly in the United States, while the last two techniques were pioneered by Bunin and Andres in the Soviet Union and introduced to the West by Andres. The principles underlying the three separation techniques will be discussed. View full abstract»

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  • Buildup of particles on fibers in a high field-high gradient separator

    Publication Year: 1976 , Page(s): 463 - 465
    Cited by:  Papers (19)  |  Patents (1)
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    In previous publications the performance of a high field-high gradient magnetic filter was calculated using a particle trajectory model to obtain the capture cross section of the fibers. The configuration of the particle buildup was assumed to be constant without considering the forces on the particle after impinging on the fiber. We now calculate the equilibrium configuration of particle buildup on the edge of a flat ribbon considering only the magnetic and viscous forces and including the effect of the fluid boundary layer. The configurations obtained as a function of field and flow are consistent with the few approximate direct observations reported in the literature. The performance of the filter, calculated using the particle trajectory model, now modified by this equilibrium buildup configuration, is compared to previously reported experimental results on separation of CuO from Al2O3slurries. A somewhat better fit is now obtained over the entire range of fluid velocity and fields, but an adjustable parameter affecting the viscous drag on the collected particles is required. View full abstract»

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  • Single wire model of high gradient magnetic separation processes I

    Publication Year: 1976 , Page(s): 466 - 470
    Cited by:  Papers (10)
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    A rate equation is being developed to model the buildup of single-sized, weakly magnetic particles on a single ferromagnetic cylindrical wire. The equation relates the rate of buildup on the wire to the fraction of the incoming particles that are captured and the portion of the particles that are carried away by the fluid stream. The theoretical predictions and experimental results generally agree well for a range of field values, flow rates, and particle concentrations. A more accurate model of the collection process will enable development of more accurate models for arrays and entire filters. View full abstract»

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  • The motion of small paramagnetic particles in a high gradient magnetic separator

    Publication Year: 1976 , Page(s): 471 - 473
    Cited by:  Papers (5)
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    The force balance equation describing the motion of a small paramagnetic particle near a cylindrical ferromagnetic collector is presented in general form. The capture cross-section for a particle approaching a bare wire is found to be a function of the coefficient of magnetic force and the magnetization of the cylinder. Calculations show that the assumption of potential flow versus creeping flow is a critical one which can change the capture cross-section by as much as a factor of three. View full abstract»

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  • Shape effect of the matrix on the capture cross section of particles in high gradient magnetic separation

    Publication Year: 1976 , Page(s): 474 - 479
    Cited by:  Papers (7)
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    A high gradient magnetic separator consists of a region of a high and approximately uniform magnetic field and a ferromagnetic matrix of fine wires which distort the field and produce large local gradients. As a particle is carried through the separator by a carrying fluid, both magnetic forces and drag forces are exerted on it. In order to gain insight into the capture mechanism, the drag and magnetic forces on a spherical paramagnetic particle were examined. The equilibrium of these forces defines the path of the particle as it passes by a matrix element. It is shown that for any geometry the particle motion is a function of two dimensionless variables. A computer with a plotter was used to compute the particle paths. In order to provide for most flexibility the magnetic field is that of a magnetized elliptical cylinder with any orientation with respect to the background field and flow stream, while the flow velocities are those corresponding to another elliptical cylinder of different configuration and orientation which allows computation of the change of capture cross section as the matrix element collects material. Examples of particle orbits and changes of capture cross section are given inthe paper for various aspect ratios of the original matrix element. View full abstract»

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  • Some old and new concepts in magnetic separation

    Publication Year: 1976 , Page(s): 480 - 482
    Cited by:  Papers (3)
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    Magnetic fields, or regions of a magnetic field have been termed isodynamic, katadynamic or anadynamic. Force constant in magnitude throughout an isodynamic field region has proved useful in concentrating particles according to slight differences in magnetic susceptibilities. In the kata-dynamic field region the highest gradients of magnetic intensity, and consequently the greatest magnetic force can be applied to a particle. The anadynamic magnetic field region, in which the force on a particle decreases in magnitude in the direction in which field intensity increases, functions in creating a magnetic barrier at which particles of low paramagnetic or diamagnetic susceptibility can be separated. The work of S.G. Frantz Co., Inc. has been concentrated since it was founded some 40 years ago in the development and manufacture of magnetic separation equipment for mineral investigation and for industrial processing. The teaching of the Company's founder, the late Samuel G. Frantz is fundamental to today's art of magnetic separation. View full abstract»

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  • Magnetic barrier--A new concept in magnetic separation

    Publication Year: 1976 , Page(s): 483 - 485
    Cited by:  Papers (1)  |  Patents (1)
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    Particles can be separated according to their mass magnetic susceptibilities by using a magnetic energy gradient barrier. When a stream of particles with different magnetic susceptibilities is fed to the barrier at an angle, a continuous separation can be obtained. The particles having susceptibilities higher than a predetermined value are deflected and guided by the magnetic barrier to a releasing region, where they pass through the barrier. Particles with lower susceptibilities which penetrate the barrier follow a different path from the more magnetic fraction and are separately collected. View full abstract»

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  • Use of high gradient magnetic separation techniques for the removal of oil and solids from water effluents

    Publication Year: 1976 , Page(s): 486 - 488
    Cited by:  Papers (1)
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    Our preliminary experience with using commercially available High Gradient Magnetic Separation (HGMS) instrumentation in water treatment problems is described. Water effluents from both a refinery and a chemical sewer have been used with flocculants to reduce total suspended solids and oil content. View full abstract»

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  • Development of high extraction magnetic filtration by the kaolin industry of Georgia

    Publication Year: 1976 , Page(s): 489
    Cited by:  Papers (2)
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    An entirely new level of magnetic filtration technology was put into full commercial production by the kaolin industry of Georgia, U.S.A. during 1973 - 1975. At present, five kaolin producers in Georgia are operating large magnetic filters each capable of producing over 4000 liters of kaolin slurry per minute or over 60 tons of kaolin per hour on a dry basis. When operated at the 4000 liters per minute rate, these five large magnetic filters have a combined capacity approximating the entire waterwashed coating and filler kaolin produced in the U.S. View full abstract»

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  • Direct reduction and magnetic beneficiation of Alabama brown ore with lignite

    Publication Year: 1976 , Page(s): 490 - 492
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    Recent developments in the direct reduction of iron ore and recent growth in its application stimulated the investigation of direct lignite reduction of Alabama brown ore. Essentially complete reduction followed by sufficient agglomeration of the reduced iron was achieved so that grinding followed by magnetic separation appears feasible. The finely divided iron should be especially amenable to high gradient magnetic separation. Initial efforts with a crude electromagnet were promising, but reoxidation of the iron was a problem with the high gradient system. View full abstract»

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  • A superconducting magnet system for a very high intensity magnetic mineral separator

    Publication Year: 1976 , Page(s): 493 - 497
    Cited by:  Papers (1)  |  Patents (1)
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    The basic cryogenic engineering requirements for building a superconducting magnet system for the magnetic separation of minerals are considered. The different construction problems for solenoids and non-circular coils are considered. The solution adopted is epoxy impregnation with high density glass-fibre inserted to control the difference in expansion coefficient between epoxy resins and the winding material of the superconducting magnet. The short hold-time cryostat required for preliminary measurements is described and proposals made for a small scale pilot plant machine with continuous refrigeration. View full abstract»

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  • Beneficiation of selected industrial minerals and coal by high intensity magnetic separation

    Publication Year: 1976 , Page(s): 498 - 502
    Cited by:  Papers (4)
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    This paper presents the results of test work performed with a Pacific Electric Motors (PEM) high intensity magnetic separator (20 kilogauss), a unit capable of separating weakly, as well as strongly, magnetic minerals in the particle size range of sands to clays. Tests were performed on selected industrial minerals and two Indiana coals. With some minerals excellent separations were attained and with others intermediate and poor separations were accomplished. This study is a preliminary survey and many of the intermediate and poor results can be improved as separation problems are worked out with additional test work. View full abstract»

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  • The application of a superconducting magnet system to the cleaning and desulphurization of coal

    Publication Year: 1976 , Page(s): 503 - 506
    Cited by:  Papers (1)
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    The basic requirements for high gradient, high intensity magnetic separation are reviewed and process limitations are emphasized. The principle innovations of the superconducting magnet system design for this work include an annular quadrupole magnet and corresponding slurry channel operating in an open field without secondary poles. The transverse secondary circulation set up in the slurry through the primary orbital flow is used to transport all particles into the region of high field intensity. Two Pennsylvania coals with high pyrite contents were treated. Test conditions and results are described and discussed. One of the coals yielded 81% recovery of "clean" coal and over 85% rejection of pyrite. Possible further improvements are discussed. View full abstract»

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  • High gradient magnetic separation of mineral particulates from solvent refined coal

    Publication Year: 1976 , Page(s): 507 - 510
    Cited by:  Papers (3)
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    Inorganic sulfur and ash-forming mineral matter have been removed from solvent-refined coal by high gradient magnetic separation at temperatures up to 587°F. Reduction in sulfur and ash content is temperature dependent and is correlated with the H/v ratio. View full abstract»

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  • High gradient magnetic separation: Effect of temperature on performance

    Publication Year: 1976 , Page(s): 511 - 512
    Cited by:  Papers (2)
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    A simple model is formulated to determine the effect of temperature on the filtering ability of HGMS devices. An optimum temperature range is observed to exist for which the capture of ash-forming minerals and inorganic sulfur in liquid coal is at a maximum. Model will serve as a framework for analyzing experimental data in future. In the past, some pertinent, independent variables such as particle size, slurry velocity and applied magnetic field which affect the performance of HGMS de-Vices, have somewhat been investigated both theoretically and experimentally. The effects of these important variables have been well established. A program is currently underway at the M.I.T. Francis Bitter National Magnet Laboratory to study the applicability of HGMS to products from coal liquefaction processes. As part of this program, the effect of temperature on the performance of filtering ash-forming mineral impurities and inorganic sulfur from liquefied coal is being explored. This introduces an additional variable- temperature -which is to be investigated among other relevant variables of the system. In particular, by varying the operating temperature the trade-off, between the lowering of the viscosity of the fluid as the temperature is increased and the attendant decrease in the magnetization of magnetic particles, is to be studied. In view of these considerations, a simple model has been formulated to predict the effect of temperature on the filtering ability of HGMS devices. View full abstract»

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  • Pilot-scale studies of sulfur and ash removal from coals by high gradient magnetic separation

    Publication Year: 1976 , Page(s): 513 - 521
    Cited by:  Papers (5)
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    This paper presents the results of pilot-scale studies of sulfur and ash removal from coal by high gradient magnetic separation (HGMS). Work was done on both the liquefied coal and the raw pulverized coal in water slurries. The effects of residence time, field intensity, packing material and density, slurry concentration and recycle on the grade and recovery of the wet separation of sulfur and ash from water slurries of Illinois No. 6 coal were quantitatively examined. The HGMS was effective in reducing the weight percent of total sulfur, ash, and inorganic sulfur by as high as 40, 35, and 80%, respectively; while achieving a maximum recovery of about 95%. The results have also provided the first experimental verification of the applicability of Bean's magnetic filtration model in quantitatively correlating the data obtained from the pilot-scale beneficiation of coal slurries by the HGMS. The successful verification of the model allows one to quantitatively identify the trade-off of operating parameters so as to optimize the magnetic removal of sulfur and ash. A pilot-scale HGMS system for the magnetic sedation of mineral residue from the liquefied coal has been designed and constructed. Typical results from preliminary experiments with the liquefied solvent refined coal (SRC) have been quite encouraging, indicating that the HGMS was effective in reducing the total sulfur and ash contents by as high as 70 and 76%, respectively. Finally, the liquefaction of the magnetically treated Kentucky No. 9/14 coal was studied and compared with that of the untreated coal. It was found that although the mineral matters which had been removed magnetically had a significant catalytic effect on the liquefaction behavior, the organic hydrodesulfurization remained practically the same for both the untreated and treated coals. This suggests that the magnetic removal of mineral matters prior to liquefaction may be advantageous for the SRC and other related liquefaction processes, in which the minimum hydrogenation is especially desired and the hydrodesulfurization is often limiting. View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology