Before commenting I'd need a few more details -

Material and density

Material flowability

Relationship between the belt conveyor and the 6 outlet points ■

My inclination would be to discharge the belt conveyor into a chain conveyor. Under the chain conveyor there would be 5 'robbing' or 'bleed' conveyors (chains or screws) each of which would remove on sixth, the final sixth being discharged from the final outlet of the chain conveyor.

No doubt others will post alternative suggestions. ■

If the pan feeders are set to deliver 200tph then there is no problem!■

Is the reclaim rate as constant as the feed rate for all ports

Curragh's 20 km overland (OLC) discharges into a large receiving hopper or bin at up to 2500 t/h. The bin is partioned to feed any one of five reclaim locations: wash plant and storage stockpiles, at programmable rates to each.

We have assisted in the design and simulation of its single entry and five exit port storage hopper. Each of the five exit ports can be reclaimed at its desired reclaim rate. The feed to each partion is regulated by bin level. The single feed point has a programmable distributor to feed the partion who's level is lowest or has not been programmed to skip. This sequence allows for non-uiniform feed and reclaim of any partion in the bin.

Works quite well. You can obtain more information from Laing O'Rourke in Australia attention to Mr. Brad Lawson: lawson@laingorourke.com.au ■

Preferred method is as described to feed from one bin, so arrange the feeders in 2 rows of 3 so that the bin area is as small as possible.

Failing that, use a slow moving radial slewing belt that moves back & forth like a clock pendulm to distribute the material between smaller bins. Bins must be big enough to hold a buffer greater than the time for the slewing belt to get back to it in the cycle. ■

There are many solutions. The solution must fit the objective and the givens of the problem.

You could have very diverse demands on the singular feed. For each there is a preferred solution. This forum is limited in speculations, and we try not to indulge in far reaching variances to an identifiable problem yet undefined.

Hyperbole is a difficult domain for simple-mind engineers. KISS it. ■

As you seen to asking for real world answers to a stockpile problem and simply told us next to nothing about it:

The use of a manually controlled tripper feeding a 6 section/drawpoint surge bin using single speed apron feedefrs are the simplest and least expensive way of doing things in my opinion and the least troublesome in my experince.

The drawpoints would be active with apron feeders properly sized or the 200 tons per hour of drawdown per the weight of the material per cubic foot feeding six belts.

Our single apron feeder which we have almost zero problems with over 23 years was 36 inches wide feeding 450 TPH ROM Halite 24 hours per day from a 75 ton nin with an inverted cone sized for 80 percent of the apron feeder width and using skirt boards and a metering gate at the discharge end.

You have to help us to help you to help us to help you! and we can collectively try to solve your problem if possible.

If you want real world examples of iron ore look at the loading docks used for loading iron ore on Lake Superior in the United States.

The hopper cars or snmall ore jennies in winter are pushed by locomotives on to the loading dock which is high over the quay and the ore is dumped into the bins and simply gravity fed using a balanced gate chute when an ore boat docks to be loaded.

The old methodologies still work and haves worked for over one hundred years.

lzaharis ■

The six partitions can be fitted with vibratory feeders, apron feeders or belt feeders. Each can do a reasonable job.

My personal vote in belt feeder. The Rio Tinto Iron Ore Ranges in Western Australia are almost all fitted with belt feeders. I have not checked, but since BHP copy many of Rio's methods, I suspect they do also. This allows elimination of one tier of conveyors, when you try to apply magnets and metal detection cleaning, prior to stockpiling or placing on the OLC.

Coal is ofter done by vibrating feeders.

If you want highest maintenance and highest cost own and operate, go for the apron feeder.

The six partitions can be designed to have fixed, variable, dynamic and accurate (+/-<1% error)programmable reclaim rates. This technology is well known.d

Those that say not so, have not done it. Many others have done it for sufficient years to make it common practice. ■

Dear Mohandes,

You can divide the receiving bin into 1-10 or more depending on your real estate.

Curragh’s receiving bin was about 500 T, allocated among the five partitions, by memory. The reclaim rates were not the same for feed to wash plant or stockpiles. As I said the feed conveyor was operated at a peak flow of 2500 t/h. However, when the bins become critically full, the 20 km OLC is first reduced in speed in stages of 7.5, 6.0, 4.5, and 3.0 m/s to continue to operate the overland before its shutdown.

The speed ranges were selected to minimize belt and structural return strand vibration modes. Commissioning was done in 2007. The specified speeds were found to be the best, for the range of tonnages commensurate. ■

Dear Mr. Mohandes,

Earlier respondents have already given useful guidance / information. Some addition from my side is as below:

It seems you have one incoming conveyor bringing iron ore at the rate of 1200 mtph. This material is to be subdivided into 6 flows, each of 200 mtph. It is not possible to give specific solution here but I would mention about basic consideration or governing aspect.

1) This issue pertains to system engineering.

2) The hopper feeding system (item), hopper arrangement and outgoing system arrangement is decided in a comprehensive manner. I mean to say whether the 6 lines are feeding into 6 crushers or 6 screens etc. and their best possible arrangement (placement), considering in totality the influence on hopper arrangement, the accessibility / maintenance aspects of the screens or crushers, and again the outgoing system from these items, i.e. whether all 6 are again merging into one or they are going in different direction.

3) The important issue is placement of the equipment dealing with 6 flows and total arrangement considering performance, reliability, ease of maintenance and price. The solution is subjective to engineering competence, preferences / prejudices and so many things and cannot be quantified. Distribution of material into hopper or division etc. have routine solutions.

I dealt with one lignite handling plant where there was this type of problem because of the limited capacity of the screens as compared to the inflow. Possibly it had 6 screens. So arrangement of screen house along with the hopper etc. was the dominant issue and not how to distribute and recollect the material.

Hope information may be of some use.

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

Email: parimul@pn2.vsnl.net.in ■

Split feed six ways

Without site details, this is a generalised problem calling for a fundamental review of options. Unless a receiving hopper can be used with six vibrator feeder outlets, it would seem that there are three basic issues to consider. The first is a problem of dividing the flow in a controllable manner. The second is the logistics of transferring the streams to the required dispensing points and the third is balancing the output of the final dispensers to match the total input from the belt conveyor.

If a common hopper can be used, the division can be met by using six feeders. Either all the feeders need to be variably controlled to increase or decrease output according to the supply changing the level of the bin, or some feeders can be set to a chosen output and one or more either take all the rest as an overspill, So much for the simple solution.

Separating a heavy flow stream of abrasive material needs to be done with the minimum contact surface pressure or by utilising a ‘dead bed’ of product to avoid excessive wear on the impact region. To create six streams, the belt discharge can be collected on a flat chute incline to the tangent of the trajectory at a slope on which the material will slide on itself, having up-stands to retain a dead bed of product. A dead pocket of material at the end of the chute that is movable across the flattened flow stream can be made to give a 1/3, 2/3 split onto side chutes. The 2/3 side have a similar arrangement to form three equal streams, which are then spilt again to form six. (perhaps awkward, but so is the task).

Assuming these streams can be directed to the required feed point, the final requirement is to balance the rates. Clearly, all that is delivered has to be cleared so objective must be for equal rates of each feeder, or set some and let the rest take the balance. There are still two choices: - Accept a rough, but adjustable, division, in which case each feeder has to clear what comes, with division trimming to adjust gross discrepancies, or set the feeders all to vary simultaneously and trim the divisions continuously to avoid excess difference in the levels in the six feed hoppers.

This approach assumes plenty of headroom and some clever control guys to accommodate the feedback delay between bin level and division adjustment, but if you set a challenging question you may receive a demanding answer.

Interestingly, a bin screw discharge method developed by Ajax Equipment to feed to two locations will extract live flow from a mass flow bin to deliver a pre-set or adjustable rate to either outet, or both outlets at the same time. An extended version will feed One, Two, Three or Four outlets at the same time in any combination, i.e, any one, any two, any three or all four independently controllable, whilst each time extracting over the total area of the bin outlet from the one bin discharge unit. ■