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Thread: Generation of Dust

  1. #1
    sudipkgh Guest

    Generation of Dust

    In our Reduction lines ( Aluminium Smelter) we have flourinated alumina and bath material being fed to pots for the smelting operation . In one pot room there are 144 such pot . The bulk material are stored in individual silo . The flourinated alumina is fed on a chain conveyor and the bath is fed on a dense phase airslide system . They are delivered in a chute which has three concentric section . From the inner circle the flourinated alumina flows , the crushed bath flows from the central one and the dedusting extraction is from the outer ring .

    The PTA crane comes below this chute and the hopper in the PTA gets filled up with the mix . When the hopper is full the PTA crane moves out . There is dusting during the filling as well as when the PTA leaves the filling chute .


    What are the points to be checked for resolving this issue . This is a long outstanding issue .

  2. #2

    Alumina dust control

    Keep the telescoping chute close to the material in the pot so that it does not have far to fall.

    You must check the design airflow flow of the dust collection system and measure it to see if it is being maintained.

    Is the bagfilter blinded? Are the ducts blocked?

    Do not move the crane too soon after filling a pot, allow the dust to clear.

    It sounds to me to be a lack of airflow.

    Michael Reid.

  3. sudipkgh,

    The comments given by Mr. Reid are all valid.

    However, can you supply additional information: such as drop height, retention time after transfer before the crane is moved, type of dust collection system used (if any), orifice size, chute/pot skirting size, et cetera.

    As Kieth indicated, airflow, air pressure, and filters are important for dust containment. Depending on your chute design, there may be some simple means of managing the dust.

    Suggest you visit the website of Martin Engineering (www.martin-eng.com) to see some of their solutions.

    Good luck in "clearing the air".
    Dave Miller
    ADM Consulting
    10668 Newbury Ave., N.W.,
    Uniontown, Ohio 44685 USA
    Tel: 001 330 265 5881
    FAX: 001 330 494 1704
    E-mail: admconsulting@cs.com

  4. #4
    sudipkgh Guest

    Alumina Dust Control

    Thanks for your reply . While I will focus on the issues identified by you may I also describe the dust extraction system ducting arrangement . The suction duct ( 150 NB ) from the chute gets divided into two separate ducts ( 150 NB each ) . The ducts are then terminated on the top of the a) Chain conveyor and b) airslide respectively . There are suction points at the other end of the chain conveyor and airslide respectively ( 10 metre distance ) and individual ducts then travel vertically upwards to the top of the silo . There are individual dust extractors on the top of silo
    It looks to me a bit odd since the ducts are not directly connected to the dust extractors and travel through different media .

    There is another issue which is a gut feeling of mine . When the PTA crane comes for filling the hopper top of the PTA may

    i) either contact the chute bottom to reduce spillage during filling
    In this case the entrapped air inside the hopper need to escape and it can escape only if the dust extraction fans can remove this air . Otherwise this air will cause a lot of turbulence inside the chute and even extending within the airslide and the chain conveyor . The moment the hopper contact is released and the crane moves the dust /air which was under turbulence finds the easiest route through the opening of the chute

    ii) remain at a gap since during filling of the hopper the entrapped air inside the hopper need to escape and it finds the easiest escape route through the gap

    So in both options there is dusting which we have found for ourselves .

    The other issue could be the flow rate of flourinated alumina and crushed bath which at their maximum value could have some significance on the size of the hopper in the PTA crane . Does sizing of hopper depend on the incoming material flow rate .

  5. #5
    Your description indicates an inadequately designed system. 150 dia. ducts do not carry much exhaust air.
    It seems that the crane hopper has no exhaust at all. I assume that the silo filters provide all the exhaust air. Is this correct?
    I can offer more detailed comment if I can see a drawing of the system.

    Michael Reid.

  6. #6
    Lawrence K. Nordell

    Lawrence K. Nordell

    President and CEO

    Conveyor Dynamics Inc. [eDir]

    Conveyor Dynamics Inc.

    Professional Experience 58 Years / 8 Month Lawrence K. Nordell has 58 Years and 8 Month professional experience

    Discussions 2608 Lawrence K. Nordell acceded to 2608 discussions, Articles 0 Lawrence K. Nordell wrote 0 articles, Publications 0 Lawrence K. Nordell Nordell released 0 publications

    Searching nothing specified

    Know-How Design (1521) Lawrence K. Nordell used this tag 1521 times, Pipe Conveyor (238) Lawrence K. Nordell used this tag 238 times, Chutes (119) Lawrence K. Nordell used this tag 119 times

    As Mr. Reid and Miller have pointed out, more information is needed to give a proper comment.

    1. A picture is worth a thousand words
    2. Particle size distribution is needed to define the level of dusting
    3. You need an engineering tool that provides the gas dynamic velocity gradients, in all dimensions, produced from the granular flow field, including the areas of escaping dust.
    4. This tool exists - see our website: www.conveyor-dynamics.com

    Lawrence Nordell
    Conveyor Dynamics, Inc.

  7. #7
    sudipkgh Guest

    Dust control

    The drawing requested is attached .

  8. Dear sudipkgh,

    In general, dust emission containment means (equipment) are there; and on that account remedies are very much available.

    However, solution to your problem possibly is more concerned with how to incorporate these means in to your existing set-up / equipment, without hindrance o your main function.

    It is difficult to make real practical suggestion without seeing or exactly knowing your equipment in engineering terms. I suggest you to involve bulk material handling expert and dust control expert (competent company) to find out joint solution, after seeing your equipment and studying your needs.

    You have to also see how to implement the solution without discontinuation of your plant operation, in predefined timeframe and modality.

    Regards,
    Ishwar G Mulani.
    Author of Book : Engineering Science and Application Design for Belt Conveyor
    Advisor / Consultant for Bulk Material Handling System & Issues.
    Email : parimul@pn2.vsnl.net.in

  9. #9
    Join Date
    Apr 03
    Posts
    11
    Dear sudipkgh,

    There is a company called Air Control Science, which has an extensive experiance in dust controls and Aluminium Smelter like Alcoa and others.

    I would give them a call and see if you can some help:

    303-530-2108 and you might like to talk with Steve or Ingo.

    Best regards,

    Grzegorz

  10. #10
    Lawrence K. Nordell

    Lawrence K. Nordell

    President and CEO

    Conveyor Dynamics Inc. [eDir]

    Conveyor Dynamics Inc.

    Professional Experience 58 Years / 8 Month Lawrence K. Nordell has 58 Years and 8 Month professional experience

    Discussions 2608 Lawrence K. Nordell acceded to 2608 discussions, Articles 0 Lawrence K. Nordell wrote 0 articles, Publications 0 Lawrence K. Nordell Nordell released 0 publications

    Searching nothing specified

    Know-How Design (1521) Lawrence K. Nordell used this tag 1521 times, Pipe Conveyor (238) Lawrence K. Nordell used this tag 238 times, Chutes (119) Lawrence K. Nordell used this tag 119 times

    Another Reference:

    Benetech, Inc. is an international supplier of:

    Total Dust Management,
    Process Gas Conditioning,
    Combustion Enhancement, and
    Material Flow Control Systems

    Their contact details are:

    Attention: Mr. Chris Blazek
    Vice President
    blazekc@benetechusa.com
    www.benetechusa.com

    1851 Albright Rd
    Montgomery, Il, 60538
    USA

    ph: 630-844-1300
    fx: 630-844-0064

    Wishing You Success,

    Lawrence Nordell
    Conveyor Dynamics, Inc.

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