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Thread: Cleaning of Belt Conveyor

  1. #1
    Join Date
    Nov 02
    Posts
    7

    Cleaning of belt conveyor

    Hi All,

    We are into production of Primary Aluminium and due to the process requirement lots of bath material is handled, which is abrasive powder but due to operation at high temperature forms into lumps.

    Though we put two to three stages of scrapers, still these material stick to the belts, and is visible under the return belt, where the materials accumulate below the conveyor belt, though we use antistatic belt.

    Any suggestion?

    Sushanta

  2. Dear Shri Shushanta,

    The solution for usual powdery material could be external scraper of proper type followed by rotary nylon brush. However, if the material is very abrasive, rotary nylon brush life may be a question.
    If the conveyor is very long one can also think of belt turnover on the return side.
    The economical / practical solution will depend on conveyor length. If the conveyors are of very short length, one can clean the belt to the extent possible, and then regularly clean underneath area of the belt, may be 2 to 3 times in a day. The material so cleaned could be put back on to the belt.
    I suggest you to refer the matter to manufacturers of the belt cleaners, who may have experience specific to the material mentioned by you and possibly better solution.

    Regards,
    Ishwar G Mulani.
    Author of Book : Engineering Science and Application Design for Belt Conveyor.
    Email : parimul@pn2.vsnl.net.in
    Tel.: 0091 (0)20 5882916

  3. Dear Shushanta,

    After confirming that your present cleaners are, in fact, properly positioned and tensioned, you can consider using one of the following on the underside of the belt - just past the discharge pulley:

    [1] A wash box, which should consist of two to three scrapers plus high intensity water spray.
    [2] A series of spiral lagged return idlers, or worm gear style return roller. These should be positioned slightly high, so that the belt maintains pressure.

    [3] Two "Squeegie" style dual or tri ply rubber blade cleaners, with tensioners to maintain good contact.

    [4] Any other option suggested by your belt or conveyor accessories suppliers.

    Whichever method you choose, it is advisable to install a collection system to handle and dispose of the carryover material - so you do not have to spend manpower on regular clean-ups.

    Some operators have had success with belt beaters (commonly used with sidewall belts) to help loosen the material from the belt. These are installed between return idlers so that the rolls beat the bottom (pulley side) cover of the belt.

    Regards,
    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
    gmahon Guest
    Hi Sushanta,

    What temperature are you conveying the bath at? A number of smelters we service, have exposed their belts to temperatures which have exceeded the belts temperature rating, resulting in belt surface damage, & "crazing" or cracks. Is this occuring in your situation, or does it occur on new conveyor belting as well?

    ADM Consulting has suggested wet belt cleaning (which works very well), however you would need to implement a belt drying station as well, since any moisture which gets into the bath on the carry side of the belt, may cause excess fluoride emissions as a minimum or a large explosion as a worst case, after the bath is reintroduced into the cells.

    Disposal of the wet bath dust (mud) then becomes an issue - as it should not be reintroduced back into the cells. Quantities will amount to the same as is currently picked up off the floor, so it is a significant new waste stream which can't be reprocessed.

    An alternate is the use of an air knife. This allows you to reprocess the dust, but does use quite a bit of air (approx 30 m3/min @ 1 bar) and obviously requires dust collection, but you probably already have that at the head of the belt anyway.

    If you require more help, please advise.

    Best regards
    Geoff Mahon
    Alcan Engineering
    geoff.mahon@alcan.com

  5. #5
    maurice.derks Guest

    cleaning of conveyor belt

    Hi,

    Recently I solved such a problem by shaping only the lower strand into a pipe (like a pipe conveyor). Requires special belting.

    regards

  6. #6
    omlesna aled zurc - Philippines Guest
    Hi Sushanta,

    First we have to find-ou the following information before gone through the proper analysis and concrete recommended action to your concern.
    I understand this conveyor but I can't visualized where this located. Is it from the Alumina Silo going to Pot Room or Inside the Pot Room it self. If it is inside the Pot Room, it will surely affect the belt from heat and electro motive forces (emf). So even you use the Antistatic belt it will a waste and expensive material for that application. Normally Std belt are made up of nylon and rubber, the nylon are re-enforcing the entire belt and the rubber is the one expose to the material being tranported. Any change in temperature (hot or cold), the characteristics of the surface affected. Like for example in hot areas, the surface will be soften and tend to stick your powder material. In long term used the surface become hard (theoretical cured due to the heat) and cracked that tends the powder go through the slot and start to accumulate and become lumps. Scraping is not recommended because you are destroying the belt surface finish either use of soft scraper it just immediately wear the edge based on the lump pattern build-up. Brushing is also not sufficient because it can not remove the powder in between the crack area where the bulid-up starts.
    One achievement design I made with my customer similar to this application is with the use of Air Knife that successfully remove the foreign material and at the same time it cool off the belt during operation. If your concern is the huge dust collector to fit in, I have a bright idea or concept to minimized such concern.
    If you wish to understand more pls let me know.

    rgds,

  7. #7
    rekhawar Guest

    Cleaning of Belt Conveyor Return side

    Dear Mr. Omlesna aled Zurc,

    Your idea of using Air Knife appears to be useful since there will not be any physical contact of blade and the belt.

    We too face similar problem in our Cross Country Conveyor, by which we carry Iron Ore, Pellets, Lime Stone, Dolomite and Coke. the problem of carry over material is severe. Lot of manpower is needed for continuous cleaning of piled up spillage below every return idlers.

    We have tried Tungsten Carbide tip belt cleaners, however they do not last very long and eventually becomes ineffective.

    At present we are trying to put a set of 8 -10 return idlers at a gap of 300 mm near to the discharge pulley. With this arrangement at least the spillage problem will get confined to a particular location.

    We do not have any plant air line available near by. For air requirement, we may have to install a dedicated air compressor.

    Will you please elaborate more on the concept of air Knife?

    Regards

  8. Dear Mr. Shusanta,

    Earlier respondents have given interesting information. In my earlier reply I had suggested use of scraper, rotary nylon brush and belt turnover.
    Additional suggestion / opinion are as below :
    1) Having placed proper scraper and nylon brush (if permitted considering the material), one can place flapping action return idlers for 10 to 12 m length from head end. The flapping idlers will help to dislodge most of the material in this zone, which can be collected and placed back onto the belt.
    2) Proper grade HR belt could be one solution if belt is cracking and the material is penetrating in to the belt structure. The HR belt, as the name signifies should not crack / deteriorate with temperatures, for design service life.
    3) Air knife will certainly clean the material. However the dust so dislodged will spread into environment and may also amount to loss of material. Please see whether this is allowed. How about placing the air knife after the flapping return idler zone?

    Regards,
    Ishwar G Mulani.
    Author of Book : Engineering Science and Application Design for Belt Conveyors.
    Advisor / Consultant for Bulk Material Handling System & Issues.
    Email : parimul@pn2.vsnl.net.in
    Tel.: 0091 (0)20 25882916

  9. All interesting stuff, I would be keen to learn what U test and try out and how it performs.

    From the cement industry side, we have simil. issues and we can not use wash boxes and have to be wary of moisture effects on the carried material.

    Air knifes are OK in used in the head chute. If the belt is cracked and the material is in the cracks, then the best place to remove this material is when the cracksa re opened up ie when going around the head pulley > so place the air knife there. U will need dust collections syetms to counter the added air and dust generation.

    An Aussie co. is pushing a push/pull system - enclosed box on the ret, side with air knife and dust extraction...on Al. industry...I do not know how well this works...try Northern Conveyor Alliance...GULF group.

    Air knifes uses energy, if using comp. air, then expenive and if using small side channel blower - noisy.

    If the air knife is out of action ,material will sit on the knife and it the material reacts and hardens with moisture..the nozzle will get clogged up....prob. with cement.

    We have used Rema rubber brushes at high speeds - creates an air draft whirl as well....works OK...but need to adjust as rubber bristles wear...can get anti static brushes.

    We have tried to look for charged static knifes/rods to remove by elec. sttraction the dust...but can not find a product to test....

    We have used plain steel idler rolls with steel round bars welded on.....create the flapper effect as decribed earlier....OK...but can get fatigue issues.

    My favourite solution is to install several rubber lagged plain ret. idlers (small diamter for higher spin speed) just after the head chute to fling the material off and install a covered drag chain to return the material to the head chute...The idlers are set up a bit to deflect the belt to break up the surface carryback....ie same as bend pulley does.

    After that, U could use RDRT type rubber disc return idlers...U can get custom made ones with the rubber dics in the positions that U wnat ie not in the middle where the carryback is most likely to be.

    Hope this helps


    James M

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