Dear Hua,

I cannot co-relate any machine & so un-able to answer. For example- a bridge reclaimer is used where blending is required & the same is used in base mix yard. Where as bucket wheel reclaimer is used for reclaiming the material where blending is not required.

Portal scraper is used to reclaim very sticky material . So selection of machine is based on application. So advantages /disadvantages cannot be done. Please specify catagorically.

Regards.

A.Banerjee ■

Dear Mr. Hua,

The answer to your question could be very lengthy and it cannot be written in this forum.

Briefly, various types of reclaimers have evolved during long history of bulk material handling. Today we are using certain type of reclaimers which have passed the test of their evolution. Other types might have been also designed but have gone in oblivion.

Presently used each type of reclaimer must be having certain edge over the others for a particular function and only then it can survive in the competitive business world for the application. Therefore, firstly it cannot be said that particular type of reclaimer is the best etc.

The “bestness” is always in context of price and operational needs. Presently following types of reclaimers are commonly used, and I am mentioning its widely used applications only :

1) Bucket wheel on slewing and luffing boom. This machine is widely used for reclaiming operation. Its reclaiming element is buckets which is of solid heavy plate without any complex parts coming in contact with the material during reclaiming.

2) Bucket wheel on bridge : This machine is widely used for reclaiming wherein simultaneously it has to blend the material. Here also the reclaiming element is bucket which is of solid plates without intricate items coming in contact with material. This machine does blending along with reclaiming but compared to bucket wheel on slewing lufffing boom it may have certain disadvantages when purely reclaiming operation is needed.

3) Scraper reclaimer machines : These are in various versions such as side scraper reclaimer which can be pylon type reclaimer, side scrapers reclaimer but reclaiming boom supported by the portal etc. The portal type of reclaimer can have much longer boom. The side scraping operation allows the machine to reclaim any portion of the stockpile because machine is riding over the stockpile. The bridge type scraper reclaimer is used when requirement for blending ratio is very high. This machine is moving though the stockpile (while reclaiming), therefore, it can reclaim only the open end of the stockpile. So the minus point is that it cannot reclaim any arbitrary portion of stockpile, compared to side scraper. It is also susceptible to variation in material flowing characteristics. The scraper reclaimers reclaim by scraper flights mounted on chain. All these items come in direct / indirect contact with the material.

4) There is also barrel type reclaimer. It is used when one wants to blend the material while reclaiming. It gives excellent blending ratio. The reclaiming arrangement is bucket of solid steel without intricate items coming in contact with the material.

There are manufacturers for all these types of machines and it will be improper to discuss your question in further detail as statements are always in context. Each type or reclaimer has its own merits with respect to application and price. There may be other types of reclaimers also, and their manufacturers can put their views.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

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 ■

Blending with a side scraper depends as much on the harrow as it does on the buckets. A deficient harrow will cause erratic fines flux into the bucket paths. There can be fluctuations of fines flooding or coarse bedpile starvation if the machine is left to its own devices.

The geometry of a side scraper leaves a lot to be desired. Wide buckets only contact the pile face along a wall equal to the bucket height. Sometimes a much higher wall of large bedpile lumps is developed. This wall periodically collapses to flood the buckets with coarse material. Whither the blending in those times?

To prevent the wall formation it would be necessary to direct some tines directly down into the space one lump size above the bucket height. That's not an easy thing to do & I've not yet seen it done. But if somebody has pushed a tine to those depths then the blending will be as good as they claim.

I'm a bucket wheel fan. My own design of portal stacker reclaimer isn't bad either.

Barrel reclaimers have been known to crack in the middle of the shell.

It depends on how much money you have.

The best is the one that does what you want for the lowest price! ■