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Thread: Magnetic Separators

  1. #1
    ravi_aekl - Malaysia Guest

    Magnetic Separators

    Please let me know, the major advantages and disadvantages of magnetic head pulley, permanent magnet and Electro magnet used for seperation.

  2. #2
    George Baker

    George Baker

    Vice President General Manager

    Assinck Ltd.

    Assinck Ltd.

    Professional Experience 41 Years / 0 Month George Baker has 41 Years and 0 Month professional experience

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    head pulley system.......basically delivers non magnetic material to stockpile and holds magnetic material long enough on the drum to drop off and discharge to a slide takeaway chute to the ground into a hopper. This system cheaper than permanent magnet but, can be inefficient depending on BED DEPTH thickness on the belt.....more thick bed of material......less efficient.

    Permanent magnet......runs all the time.....hangs over the conveyor and draws metals up to it.....and holds it.....if lots of metals...must stop ......turn of magnet......drop material and restart....

    Both systems have their own niche application. MUST do a full system application review form prior to deciding....

    Kind Regards, GEORGE BAKER

  3. #3
    Steve Davis

    Steve Davis, B.Eng., P.Eng., CEng, CPEng, FIMechE, FIEAust

    Principal Advisor




    Tramp metal magnet installation effectiveness is dependant on the conveyor system, the material bed depth, conveyor speed, metal particle size, and the pulley configuration, and other issues.
    Magnetised head pullies generally have limitations in the amount of magnetic flux they can generate due to size constraint, and this may limit application. Pullies wear out eventually, and this may take the magnet out of commission also, requiring costly replacement. Overbelt magnets generally have extended lifetimes.
    Overbelt magnets can be permanent or electro magnets, and can be self cleaning or manually cleaned. Electromagnets generally will be able to provide the highest flux. Self cleaning electromagnets will generally be more expensive to buy and install and operate, but do not need constant attention.
    Separation of tramp metal by overbelt magnet is usually best when the material stream is in free fall, such as at the discharge trajectory from a head pulley from a belt moving at 2 to 3m/s plus.
    Overbelt magnets tend to be far less effective when mounted over the belt proper, where tramp has to be pulled through the bed of material.
    The size and location of the magnet in relation to the bulk material stream and tramp particle is critical for best operation. Most magnet suppliers will be able to give guidance in this respect.
    There are many other considerations such as magnet suspension and adjustment method, interference with chutes, cleaners and samplers, provision of non magnetic chutes, safe discharge of tramp material, temperature control and so on.
    You may need to consider installation of metal detectors to detect tramp that has passed the magnet.
    I trust this is of use

  4. #4
    Join Date
    Nov 02

    magnetic pulleys

    Dear Ravi,
    Magnetic pulleys main job is to remove larger magnetic elements from the BOTTOM of the whole burden. Main advantage is that they are working constantly once your system is in operation. Main disadavantage is that they may be used in limited applications i.e. generally only when you want to remove larger magnetic lumps from the material stream. Finer elements and non-magnetics have to be romoved using other methods. Every application requires detail analysis and if you want I can submit you my recommendation once you give me details of your application.

  5. Magnetic Separator

    Dear Ravi

    In any bulk materials handling system, tramp iron (unwanted iron particle / items / lumps) can best be removed when bulk material is conveyed on belt. This you can do by two type of magentic seperators viz permanant magnet and electro magnet.

    Permanant magnet are economical in operation but can only be used for narrow belt-width light duty needs. Electromagnetic type can have very powerful magnetic flux and hence suitable for very poweful effect.

    Permanant magnetic seperator can have sub types magnetic pulley and suspension magnet.

    Electromagnetic type can have subtype magnetic pulley, suspension magnet, cross belt magnetic seperator and overband in-line seperator. Magnetic pulleys are good for removing tramp irons from bottom portion of material bed. All others are effective for upper zone in material layers. Use of both can effectively cover full depth. Overband in-line seperator can also reasonably take care of full depth.

    One opts for pulley + over head seperator when material depth is very large or when very effective result is needed. Generally, one will find over head seperators more.

    Ishwar G Mulani - Author Book Engineering Science and Application Design for Belt Conveyors
    Email ID -

  6. Dear all,

    Suspension electromagnets are less maintenance free but the operators need to have constant watch on them for periodical disposing of scraps attracted by the suspension magnets.

    Overband magnetic seperators are automatically throwing away the steel scraps from the conveyors which need less attention from the operators but more prone for maintenance due to rotating parts, rollers, belts, plummer blocks, drive mechanisms etc.,

    Have you any one see the benefits of both ?

    It is like this : Suspension magnet on motorised movable trolley. After the intervals of predetermined timings, the suspension magnet will be automatiaclly taken out. The scraps will be dropped in the collection chute. Move back to its position. Again getting on for attractin the scraps. Is it known as AOMS ( Auto Over head travelling magnetic Seperator ? )

    Thanks & Regards,

  7. #7
    Join Date
    Mar 03
    This is a real blast from the past.
    Was it necessary to resurrect such an old thread

  8. Dear Mr.Designer,

    I feel it is more logical to continue the old threads when there is any appropriate query is raised in the same line. So I searched old threads instead of making new query and continued an old thread.
    This will give good and complete picture for all the members who had missed or forgot the old contents of the threads again restarted. This will be much beneficial for the newly joined members and learners like me. Hope you ( and Mr.Author ) may agree.

    I am waiting for my quary posted . ( It is like this : Suspension magnet on motorised movable trolley. After the intervals of predetermined timings, the suspension magnet will be automatiaclly taken out. The scraps will be dropped in the collection chute. Move back to its position. Again getting on for attractin the scraps. Is it known as AOMS ( Auto Over head travelling magnetic Seperator ? )

    Thanks & regards,

  9. #9
    Join Date
    Mar 03
    I presume you stop the conveyor while the magnet is removed for cleaning?

  10. Yes!
    Suitable interlocks will be required either for stopping the conveyor or the material when the magnet will be moved out. It may be started again when the magnet is positioned back and energized.

    Do we have such standard equipments already available in the market ?


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