Results 1 to 8 of 8

Thread: Limitation of induced air in a transfer chute below a belt magnet

  1. Limitation of induced air in a transfer chute below a belt magnet

    We've got a transfer chute with a drop height of about 1,6m and conveyor capacity of abotu 600t/h on a 1400mm belt. There's a up to 4m long wire bolts coming with the rock from the crusher from to the belt. The most efficient and about the only way to pull these long wires (d=20mm) out, is to have an inline magnet on the discharge end.
    This then causes that we have a reasonably big opening on the magnet entrance and an even bigger on the scrap metal chute side.
    We will need to use dedusting units, but the induced air in the chute is a very big one due to the large openings.
    As we are dealing with fibers, the water fog does a certain job, not all of it.

    Housing basically would do, but with d=20mm and 4m long wires...there's always trouble.

    Does somebody have good ideas on limitign the induced air in transfer chute below a belt magnet installed inline with the belt on the discharge end?

  2. #2
    Gary Blenkhorn
    Bulk Handling Technology Inc.

    Professional Experience 40 Years / 4 Month Gary Blenkhorn has 40 Years and 4 Month professional experience

    Discussions 99 Gary Blenkhorn acceded to 99 discussions, Publications 0 Gary Blenkhorn Blenkhorn released 0 publications

    Know-How Design (315) Gary Blenkhorn used this tag 315 times, Belt Conveyors (135) Gary Blenkhorn used this tag 135 times, Software (55) Gary Blenkhorn used this tag 55 times

    Use an electro magnet as close as possible to the source of the bolts. HangHthe magnet in a tower that allows the magnet to straddle the belt. The magnet needs to be strong enough to pull the material up through the product in the belt. Run the magnet on a motorized trolley and when the conveyor shuts down it automatically moves out from the conveyor, trips a travel switch that deenergizes the magnet and drops the metal into a collection bin. The trolley can also be set at specific time intervals to ensure the magnet does not get too full.

    You also should have a metal detector downstream of the magnet that will trip and stop the belt if any metal gets by the magnet. This will require someone to lock out the conveyor and go to the downstream side of the metal detector and remove the metal. To test how far the belt travels after stopping, place a piece of metal on the belt and let the metal detector trip the conveyor, then paint a strip on the conveyor or place a sign at the spot the material has stopped at. This allows you to go directly to the metal. Sometimes a hand held metal detector helps to locate the metal under the product.

    The conveyor components below the magnet should be as non metallic as possible. Then your transfer chute can be of a normal design and metal free.
    Gary Blenkhorn
    President - Bulk Handling Technology Inc.
    gblenkhorn@bulkht.ca
    http://www.bulkht.ca

    Offering Conveyor Design Services, DEM Flow Simulation Services, Conveyor Transfer Design Services, SolidWorks Design Services for equipment layouts and Software for the Bulk Material Industry.

  3. Hi,
    Thanks Gary for your comments.
    The magnet part is clear and "simple" thing.
    The problems come, when we try to limit the openings, so that we would not allow air to be induced to the chute and finally exhaust the dust out after the transfer point.
    The stiff and long wires tend to rip everything apart and therefore normal rubber skirts before the discharge end do not work.
    We are using belt magnets, which require belt changing also occasionally. Basically housing is possible, but will naturally then make the belt change, maintenance and inspections harder to do.

    Petteri

  4. wire debris

    Is this reinforcing bar(rebar) that you are dealing with?

    Would it be at all possible for the material to be crushed or broken smaller by a crawler mounted hydraulic breaker claw
    and employing an electromagnet used on the material on a second crawler excavator before it is dumped into the conveyor
    transfer system??

    Short of that if you what you are doing is reclaiming concrete to make new aggregate you have very few options.

  5. #5

    Talking Whiplash!

    Four metre long by 20 dia. roof bolts are quite a hazard for conveying purposes.

    In one breath the magnet is described as a 'clear and simple thing' and in the next sentence the severe belt damage is acknowledged.

    Belt magnets are, of necessity, violent gadgets. In earlier days I spotted a brand new shovel on the belt. I could have used that discarded tool myself except for it having had the handle worn away before I could shut down and retrieve the shovel. If you have roof bolts exposed to a belt magnet your downtime will be very frustrating.
    Your post is excellent because it highlights the intermittent operation of some conveyor belts which are supposed to be continuously operated. Consider an examination of the crusher. It is probably a Blake (Jaw) type: otherwise the crusher would also experience downtime when the wire became wrapped around rotating surfaces. Crusher exit would be a more convenient site for a very strong fixed magnet like the one Gary mentions. At the crusher exit the nip has reduced the opening, that's what nips do, to the limit size of any, rarely, attached rock. This would make it possible to extract the bolt in less active, nearly said calm, airflow.

    The occurrence of discarded roof bolts was never quoted in texts covering comminution. That is because roof bolts where unheard of until the latter half of the 20th century. Are you crushing underground?
    John Gateley
    johngateley@hotmail.com
    www.the-credible-bulk.com

  6. #6

    Talking Whiplash!

    Four metre long by 20 dia. roof bolts are quite a hazard for conveying purposes.

    In one breath the magnet is described as a 'clear and simple thing' and in the next sentence the severe belt damage is acknowledged.

    Belt magnets are, of necessity, violent gadgets. In earlier days I spotted a brand new shovel on the belt. I could have used that discarded tool myself except for it having had the handle worn away before I could shut down and retrieve the shovel. If you have roof bolts exposed to a belt magnet your downtime will be very frustrating.
    Your post is excellent because it highlights the intermittent operation of some conveyor belts which are supposed to be continuously operated. Consider an examination of the crusher. It is probably a Blake (Jaw) type: otherwise the crusher would also experience downtime when the wire became wrapped around rotating surfaces. Crusher exit would be a more convenient site for a very strong fixed magnet like the one Gary mentions. At the crusher exit the nip has reduced the opening, that's what nips do, to the limit size of any, rarely, attached rock. This would make it possible to extract the bolt in less active, nearly said calm, airflow.

    The occurrence of discarded roof bolts was never quoted in texts covering comminution. That is because roof bolts where unheard of until the latter half of the 20th century. Are you crushing underground?
    John Gateley
    johngateley@hotmail.com
    www.the-credible-bulk.com

  7. The separation of the metals as itself is a pretty clear issue and works fine. Yes, sometimes there are damages, but that belongs to life and the extent is not a problem.
    The roof bolts are wire bolts so they do bend somewhat, but there is naturally also smaller parts and nets with concrete blocks. These are often transferred further and broken up when falling to the silos. Afterwards the loose metals are again easier to take out.

    The crusher is an undergrond gyratory crusher and also the clogged wires are dealt with in a functional way. So on that part there is no real problems.

    The problem what we are having, is that as the belt magnet, which is getting the 600t/h ore from the gyratory, through a vibrating feeder and a short belt feeder, has large opening.
    As we have a dust and fiber issue, in order to reduce the amount of induced air to the discharge chute, I'd need to cover the magnet as well as possible. But with the nets, wire bolts... the risk of getting stuck is always an issue. So hard covers stand the tear better than rubber or other soft covers.

    At the belt feeder discharge end the sides of the feeder as well as the scrap chute have walls up to the magnet. In these locations rubber still works to close the maybe 10-15cm gap between chute wall and magnet.
    But on top of the conveyor belt and at the discharge to the scrap chute, we haven't come up with a good solution to close the area. With a 1400mm belt the opening is such a big one, that the amount of air induced in the chute is very big. If we could limit the openings to maybe 50% that would already cut down the induced air by about 50% from 5,7 m3/s to around 2,9 m3/s.

  8. #8

    Smile The Thot Plickens

    As this thread develops there are underlying contradictions which must be acknowledged.
    If the tramp iron removal is simple and straightforward, belt skirt damage is insignificant & tramp iron can be removed from the silo I cannot understand the rationale of the thread. Further, what is the functional way of removing the clogged wires from the crusher.

    You are already sitting the belt magnet on top of the high chute walls which is already the best solution. You don't need any skirt there, the magnet can be arranged to sit directly on top of the chute sides.
    Upstream removal of the roof bolts & mesh, as suggest by Izaharis, is the only worthwhile improvement you can make. This is because if there is inadequate airflow in an otherwise very good installation the only way to correct this would be to enlarge the airflow. (This assumes that a rubber curtain is already fitted at the feeder exit & the working envelope of the crusher is able to withstand the whiplash.)
    John Gateley
    johngateley@hotmail.com
    www.the-credible-bulk.com

Similar Threads

  1. Goudsmit Magnetics: Chute Magnet for Animal Feed Industry
    By Author in forum Product Presentations
    Replies: 0
    Last Post: 23rd April 2015, 18:53
  2. Induced Air Fan of Cement Kiln
    By taxuantruong in forum Wear & Abrasion Problems
    Replies: 10
    Last Post: 3rd March 2014, 9:53
  3. Particle Size Limitation for Screw Conveyors
    By mohandes in forum Solutions for Screws, Segregation & Solids Flow
    Replies: 2
    Last Post: 27th March 2013, 12:32
  4. Limitation of Steep Angle Conveyor
    By A.Banerjee in forum Steep Angle Conveying
    Replies: 2
    Last Post: 28th January 2008, 9:33
  5. Induced Air Flow
    By john.rz in forum Dust Control & Suppression
    Replies: 0
    Last Post: 29th September 2006, 5:58

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Single Sign On provided by vBSSO