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Thread: Magnetic separator for ferrous raw materials

  1. Magnetic separator for ferrous raw materials

    Dear experts,

    We have many conveyors for conveying sinter or CDRI ( cold direct reduced iron ) pellets.
    OBMS ( Overband Magnetic Separators ) could not be used to remove the scrap ferrous materials above these conveyors.
    How to remove the ferrous scraps (from these conveying materials), which are potentially dangerous to slit the conveyor belts?
    Also will metal detector work, to trip the belt, if any scrap is missed by OBMS ?

    Thanks in advance & regards to all,

  2. #2
    Join Date
    Mar 14
    Posts
    3
    Dear Mr. Ganesh,
    I think, a combination of a metal detector and an overband magnetic separators with non-permanent magnet can be used in this case. When the metal detector sense a ferrous scraps, a starting command will send to the separator.

  3. Quote Originally Posted by samad View Post
    Dear Mr. Ganesh,
    I think, a combination of a metal detector and an overband magnetic separators with non-permanent magnet can be used in this case. When the metal detector sense a ferrous scraps, a starting command will send to the separator.
    Dear Mr.Samad,
    OBMS is attracting the sinter and DRI materials also, which are having more ferrous. Is there any other method?

    Regards,

  4. #4
    Join Date
    Mar 14
    Posts
    3
    Quote Originally Posted by sganesh View Post
    Dear Mr.Samad,
    OBMS is attracting the sinter and DRI materials also, which are having more ferrous. Is there any other method?

    Regards,
    Dear Mr. Ganesh
    In my suggested method, when the metal detector sense a ferrous scraps and send starting command to OBMS, it removes everything on the belt (since all is magnetic) for a short period (one second for example). The point is: "magnet of the OBMS should be non-permanent magnet" and it is off (it is not magnet and does not attract) when there is no command from the metal detector. Obviously, it can not be used when the ferrous scraps are too many since the OBMS will remove all the load. Also, it is not efficient for high capacity conveyors. I have seen this method in high grade iron ore and pellet conveying systems. I do not know any other method and I am curious about it.

  5. #5

    Unhappy Once Upon a Time.

    This problem/story is as old as belt conveying of iron ore and therefore older than steel chord belting.
    Separating materials of similar magnetic susceptibility is not really conducive to magnetic separation methods. Prevention is better than cure and implies that screening out is a remedy: once the point of introduction of tramp iron has been identified.
    It was implied, by agreement, in a recent thread that metal detectors are just a chocolate tea pot looking for a more durable chocolate. The sensitivity of any detector must be set so that the induced magnetic, radiometric or optical variation does not shut down the conveyor until it is absolutely certain that tramp iron has been encountered within the other ferrous material. Because of the variation in tramp iron this is practically impossible. The conveyor will trip frequently and the maintenance personnel will soon dispense with the sensor.
    Some sample cutters could be adapted to identify and remove tramp iron from the conveyor discharge. Such a system would have the same confusion in identifying the tramp iron but the isolating method would not stop a belt and enable material to be returned back to the mainstream. This would not protect the upstream conveyor and the earlier mentioned screening would still be a helping hand.
    John Gateley
    johngateley@hotmail.com
    www.the-credible-bulk.com

  6. Scrap Removal

    Quote Originally Posted by johngateley View Post
    This problem/story is as old as belt conveying of iron ore and therefore older than steel chord belting.
    Separating materials of similar magnetic susceptibility is not really conducive to magnetic separation methods. Prevention is better than cure and implies that screening out is a remedy: once the point of introduction of tramp iron has been identified.
    It was implied, by agreement, in a recent thread that metal detectors are just a chocolate tea pot looking for a more durable chocolate. The sensitivity of any detector must be set so that the induced magnetic, radiometric or optical variation does not shut down the conveyor until it is absolutely certain that tramp iron has been encountered within the other ferrous material. Because of the variation in tramp iron this is practically impossible. The conveyor will trip frequently and the maintenance personnel will soon dispense with the sensor.
    Some sample cutters could be adapted to identify and remove tramp iron from the conveyor discharge. Such a system would have the same confusion in identifying the tramp iron but the isolating method would not stop a belt and enable material to be returned back to the mainstream. This would not protect the upstream conveyor and the earlier mentioned screening would still be a helping hand.
    Dear All,
    Mr.Jone has given the correct advice, however I may add,
    The product being carried is probably produced in house. I have been trying the following measures to minimize belt damage by scrap with successful results.
    1. Better house keeping.
    2. Check the design of discharge chute and skirting to ensure that the chance of scrap sticking in the discharge point is minimized.
    3.Use small size liners which cannot trap and cut belt: also ensure frequent checking of all transfer points to eliminate the liners falling off.
    4. Avoid Plug-welding in case of Iron Ore/pallets and go for conventional bolting with counter sunk bolt head and welding as and when required.
    With the above actions I could almost eliminate the belt tear.
    Our experienced experts can add their suggestions.
    with Regards,
    Narayanan Nalinakshan.

  7. The arrangement proposed by samad generally reflects that I have observed in "similar" [though not identical] applications, though I propose the installation includes adjustability, so that it can be refined during: commissioning, and operation.

    Although preferred if practicable, in some industries it is not possible to remove the tramp [underground rock anchors etc].

    At least one supplier in AU purports to supply metal detectors that can reliably discriminate between: ferrous tramp, and product; however I was not able to obtain: suitable supporting technical data, or any reference installations; to confirm the same.
    Some suppliers recommend "banana" magnets for this duty.

    Graham has previously proposed the concept of transporting the tramp, via suitable infrastructure, that may have merit in your application:

    http://forum.bulk-online.com/showthr...t-Rip-Troubles

    Regards,
    Lyle

  8. #8

    Smile Proof of the Pudding.

    "Belt Rip Troubles

    No elastomeric conveyor belt can be made RIP-proof! Unless you're buying
    thousands of feet of belt, there's nothing we can put into your belt...that
    you can AFFORD...to make it LESS-LIKELY to rip.


    "Big G"
    Manager, Application Engineering
    Scandura Conveyor Belting
    2763 E. Irish Place
    Centennial, CO 80122
    303-773- Big G "

    A worthy statement from an honest manager. We need more of those!
    The tramp must be eliminated or restricted to manageable dimensions.
    John Gateley
    johngateley@hotmail.com
    www.the-credible-bulk.com

  9. Thank you all for contributing in this thread. Thanks a lot to Mr.Lyle for sharing the valuable thread.

    Many Regards,
    S.Ganesh

  10. I don't think I understood the real problem. Where is the tramp materials coming from? Is all of the feed materials laying on the ground and recovered and put on the conveyor system via a hopper? What is the material flow sheet look like? A sketch would be nice. More than likely the sinter is not magnetic, but the DRI is. It would be beneficial to catch the tramp scrap before the DRI is put on the convveyor. Perhaps a redesign of how the materials are put on the conveyor and a screen to eliminate the tramp scrap would work. But any attempt to magnetically separate the tramp scrap from all the product will be a waste of time. Send a sketch or drawing if possible through this media and we will be able to put our heads together or send it directly to us with our email addresses. Mine is: tcinc002@aol.com. If you wish to have my credentials let me know?
    Thomas J Coyne jr., President: T.C.Inc., Oregon, USA

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