What did the magsep manufacturers say: or couldn't you be bothered to ask them for the definitive answer?

Think like an ejecting fighter pilot and that should give you some clue. ■

Originally Posted by A.Banerjee

Dear Sir,

What should be the speed of belt for magnetic separator mounted on belt conveyor for separation of tramp iron? Is it more than belt speed of conveyor or little slower than belt conveyor?

Regards.

A.Banerjee

Dear Sir,

I had modified the drive of few over band magnetic separators, because exact spares were not available. I did not face any problem, when I put them in service.

The nonmagnetic "ridges or cleats" of magnetic separator belt are more important for throwing away the attracted ferrous scraps to the collecting chute.

For your question, I think that the magnetic separator's belt speed is slightly higher than that of the main conveyor, from which scraps need to be picked up and thrown away. Higher speed may give the advantage of throwing the scrap for a longer distance, thus keeps the main conveyor area and its nearby are cleaner, thus safer.

Thanks & Regards, ■

Hello,

When a space-craft lands on moon, its velocity component along moon surface (periphery) has to be very close to zero, or else it will tumble or skid. Its velocity component along moon radius has to be also very close to zero. The difference in this velocity will cause bumpy / jumpy landing. Well, it should also not be rotating on its own axis. Above is for landing without run-way.

As for the magnetic separator, there are 2 versions of its placement, viz. in-line and cross belt.

The magnet pulls up the tramp iron imparting velocity perpendicular to magnet / belt surface. So, it will have bumpy / jumpy landing, whether it is in-line separator or cross belt separator. There is no remedy to this, and magnetic force will be strong enough to catch it back from rebound, and keep it adhered to the belt.

The tramp iron was moving along the belt, and therefore it has velocity magnitude and direction accordingly. In case of in-line separator, if its belt velocity is also same as main conveyor belt velocity, the tramp iron will have soft landing with respect to this direction (without tendency to skid or tumble). So, it is good / preferred situation. Therefore, in-line arrangement is more effective, better and preferred for higher speed conveyors. Equal or nearly equal velocity of the belts is good enough as per available ratio, pulley, etc. and no need to make extraordinary efforts to match them.

In case of cross belt, it is not possible to make the landing velocity equal to zero along separator belt, because both are at right angles. So tramp iron will tumble / skid which will tend to weaken the magnetic grip somewhat, but magnet design will not allow it to fall down most of the time; if this type of separator is used for comparatively lesser belt speed of main conveyor and / or magnet is wide enough to take care of this situation.

Regards,

Ishwar G. Mulani

Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.

Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India. Tel.: 0091 (0)20 25871916

Email: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

Dear Mr.Mulani Sir,

Thanks a lot for your detailed reply. The drives modification, I had done were for cross band separators only.

I understood from your post that the in-line belts life would be better than that of cross belt separtors. However due to space constraints, the population of in-line band separators might be less than that of cross-band separators. Requesting your comment please.

Thanks a lot & High regards, ■

Hello,

Referring to my earlier reply, I add / rectify following information:

In case of in-line separator, the tramp iron pick-up is from material discharge trajectory, immediately after discharge at head pulley (as against from belt as mentioned earlier).

The tramp iron will have certain velocity (magnitude and direction), at mean pick-up point on trajectory. Now tramp iron motion will deflect as a sharp curve toward magnet under influence of resultant force arising due to gravity and magnetic force. The gravity force is constant whereas magnetic force is increasing rapidly as the tramp iron approaches the magnet. Finally the tramp iron strikes at velocity say Vf to magnetic separator belt. The velocity Vf component value along the magnetic separator (MS) belt, signifies the MS belt matching velocity to avoid tramp iron tumbling / skidding.

It appears that the in-line MS belt matching velocity could be somewhat less / more compared to main conveyor, depending upon application features (MS position / inclination, main conveyor velocity, etc.).

It also appears that the material / tramp iron trajectory has shallow angle to horizontal near discharge point, particularly for higher speed belt conveyors, and thereby the magnetic force is acting nearly perpendicular to the original motion which will result that the tramp iron final velocity component along the MS belt will be close to tramp iron original motion in trajectory.

The magnetic force action occurs in a defused manner according to the flux lines. However for simplicity its effect has been mentioned here as from single mean point.

This reply will primarily help to understand the phenomena. It is better to rely on those who regularly tackle this issue and who have necessary data i.e. competent manufacturers of magnetic separators.

Regards,

Ishwar G. Mulani

Author of Book: ‘Engineering Science And Application Design For Belt Conveyors’. Conveyor design basis ISO (thereby book is helpful to design conveyors as per national standards of most of the countries across world). New print Nov., 2012.

Author of Book: ‘Belt Feeder Design And Hopper Bin Silo’

Advisor / Consultant for Bulk Material Handling System & Issues.

Pune, India. Tel.: 0091 (0)20 25871916

Email: conveyor.ishwar.mulani@gmail.com

Website: www.conveyor.ishwarmulani.com ■

Originally Posted by A.Banerjee

Dear Mr. John,

I asked you a simple question. Why every time you give a twisted reply? Is it by nature?

Then what for FORUM?

A.Banerjee

Originally Posted by I G Mulani

Hello,

.......... It is better to rely on those who regularly tackle this issue and who have necessary data i.e. competent manufacturers of magnetic separators.

Ishwar G. Mulani

After much preamble I have agreement on my first sentence. My second sentence appears valid vis a vis the preceding sentence.

What for the forums? I ask myself that every time I read threads that could be better answered and quicker by clicking the manufacturer's website 2 or 3 times. The process often involves clicking 'products' and then 'literature'. Try it sometime and save the forums the entertainment. I for one would miss the fun. Sometimes I look up a website because I haven't a clue what the thread starter is about. I very soon find the information that answers the thread lock stock and barrel. It is surely just as easy for the thread starter(s) to do likewise. These forums started, I thought, to provide expertise and advice not normally available on other websites. I and many other respondents read threads that have often been self contradictory, incomplete, irrational or all three and more. I urge thread starters to confine questions to real issues or endure the consequences in good spirits. And, yes it is my nature.

Regarding 'twisting', I would successfully challenge in court that my analogy about an ejector seat is more near the mark than the space odyssey analogy. ■

Originally Posted by A.Banerjee

Dear Sir,

What should be the speed of belt for magnetic separator mounted on belt conveyor for separation of tramp iron? Is it more than belt speed of conveyor or little slower than belt conveyor?

Regards.

A.Banerjee

I handle Marketing Communications for Eriez, so I can't help with the technical aspects of this that others are obviously proficient in. I did however, get this quote is from Eriez' Market Manager for Heavy Industries:

"In general, we normally furnish our cross-belt magnets with belt speeds of 275 to 375 FPM. Our in-line magnets are normally furnished with belt speeds of 450 FPM. Obviously, the application could require different magnet belt speeds but these our standard speeds."

Here's a photo of one of our installs:

I would think that the original manufacturer could give you a recommendation on the best speed for your application.

Best of luck,

John ■

Following discussion with our specialist here at Eriez Europe, I'd like to add to Jblicha's reply. Generally speaking the speed of the belt of the magnet installed in-line with the conveyor is always slightly higher than the speed of the conveyor belt itself. When it comes to a cross-belt installation of the suspended magnet, the belt speed of the magnet will depend how far and fast you want the tramp iron to be thrown and therefore will depend on the weight,...

Should you need assistance in specifying an overband magnet for one of your project, you can provide us your applications parameters. Eriez has 12 affiliates around the world who will be able to assist. Addition information on suspended permanent magnets could be found in Eriez operation manuals that can be downloaded on our website.

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Originally Posted by A.Banerjee

Dear Sir,

What should be the speed of belt for magnetic separator mounted on belt conveyor for separation of tramp iron? Is it more than belt speed of conveyor or little slower than belt conveyor?

Regards.

A.Banerjee

 

Originally Posted by jblicha

I handle Marketing Communications for Eriez, so I can't help with the technical aspects of this that others are obviously proficient in. I did however, get this quote is from Eriez' Market Manager for Heavy Industries:

"In general, we normally furnish our cross-belt magnets with belt speeds of 275 to 375 FPM. Our in-line magnets are normally furnished with belt speeds of 450 FPM. Obviously, the application could require different magnet belt speeds but these our standard speeds."

Here's a photo of one of our installs:

I would think that the original manufacturer could give you a recommendation on the best speed for your application.

Best of luck,

John

Following discussion with our specialist here at Eriez Europe, I'd like to add to Jblicha's reply. Generally speaking the speed of the belt of the magnet installed in-line with the conveyor is always slightly higher than the speed of the conveyor belt itself. When it comes to a cross-belt installation of the suspended magnet, the belt speed of the magnet will depend how far and fast you want the tramp iron to be thrown and therefore will depend on the weight,...

Should you need assistance in specifying an overband magnet for one of your project, you can provide us your applications parameters. Eriez has 12 affiliates around the world who will be able to assist. Addition information on suspended permanent magnets could be found in Eriez operation manuals that can be downloaded on our website.

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