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. ■
Re: Generation Of Dust
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". ■
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 . ■
Re: Generation Of Dust
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. ■
Re: Generation Of Dust
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. ■
Dust Control
The drawing requested is attached . ■
Re: Generation Of Dust
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 ■
Re: Generation Of Dust
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 ■
Re: Generation Of Dust
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. ■
Dust
There is a book called Industrial Ventilation - good read.
In general, dust extraction volumes should cater for:
Material displacement
Entrained air in the falling material stream - less fall equals less entrainment
Expansion due to thermal effects
Creating an inflow thru all possible openings - say 1.5 -2.5m/sec,
The above book has some rules of thumb - estimation is abit of black art.
Next is the system design > ductwork and the filter/fan.
It is best to have a custom designed dust network with duct velocities carefull selected - also do not have duct runs of greatly varying lenght ( the shorter runs will always pull more air). For duct networks - use a program/software to do the calcs.
Do not use other equipment as "inter connector" ducts as described.....
Do not use blast gates for flow control...flow control is achived by duct diameter sizing.
The dust collector / fan then need to be sized correctly.
For the loading spout - consider a vibrator to help clean the cones and also a plus to stop spillage when the cones are being raised. Also - alway run the duct collection system before and run on after using the loading spout.
Cheers
James Morrish
Australia ■
Re: Generation Of Dust
G'day James,
After reading your testimonial on Industrial Ventilation, I thought I would give it a "good read". The google search turned up the five following. I think one is repeated. Can you help and tell which is your candidate?
1. HISTORY OF INDUSTRIAL VENTILATION DESIGN GUIDE BOOK (DGB), Esko Tähti, Suomen
Talotekniikan Kehityskeskus Oy (TAKE) Chairman of EUROVENT WG13 There is a ...
www.take-finland.com/tiedostot/kirjainfodgb.pdf - Similar pages
2. industrial exhaust ventilation systems. The book features tables ...
www.acgih.org/resources/press/NewTitles.htm - 36k - Cached - Similar pages
3. Industrial Ventilation: Engineering ...
Working from an engineering approach based on fundamental
concepts, it explores the design and function of industrial ventilation ...
cart.barnesandnoble.com/textbooks/booksearch/ isbnInquiry.asp?isbn=0471637033 - 45k - Cached - Similar pages
4. Design of Industrial Ventilation Systems: ...
... How to Design, Build, or Buy Industrial Ventilation Systems ... John L. Alden, John
M. Kane. Textbook Paperback - 5th ed, September 1998. New Book Price: $37.95. ...
cart.barnesandnoble.com/textbooks/booksearch/ isbnInquiry.asp?isbn=0831111380 - 42k - Cached - Similar pages
5. ACGIH Industrial Ventilation Manual CD-ROM description. Prices. Canada and
USA. CD-ROM $270 CDN or $174.90 US, CD-ROM plus book $340 CDN or $218.90 US. ...
www.ccohs.ca/products/ordering/acgih.html - 17k - Jul 9, 2003 - Cached - Similar pages
Appreciatively,
LK Nordell
Conveyor Dynamics, Inc. ■
Generation Of Dust
I think James is refering to "Industrial Ventilation-A Manual of Recommended Practice" published by The American Conference of Governmental Industrial Hygienists. It is a well used manual but needs some experience for proper application.
The problems described by the thread starter need hands-on investigation and analysis by an experienced consultant.
Michael Reid. ■
Re: Generation Of Dust
Mr. Reid:
I believe the reference you speak of is NO. 5 on my list of sources.
Ah, the second paragraph! I have pasted on references and technical capabilities of sources that may meet needs of the thread starter. Your are welcome to do the same.
We do practice in the science of air flow turbulence, have written our own Finite Volume and Lattice-Boltzman codes. We are able to do the science of problems Mr. Morrish eludes to as "black art". The codes incoporate solid, gases and fluids, to study the behavior of fugitive dust and other applications.
No further response is necessary.
Lawrence Nordell ■
Re: Generation Of Dust
Hi Lawrence,
Yes the book ref. is right, I have designed over 30 dust collections systems, mainly for conv. belt transfers.
The book was well used as were other references/papers - they all seem to have rule of thumb approaches.
In my experience, no one will thank U for a borderline system , adequate provisions should be made where ever possible (within reason) plus using gained or available experience.
A dust collection system on the whole is unstable, any single problem will usually initiate others.
It is pleasing to see someone in the Middle East attacking a work environment dust issue. I hope that they succeed.
Cheers
James ■
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 . ■