if you know the angle of repose it should then tell you all you need to know about the characteristics of the ore pellets behavior and how well it packs etc. ■

Dear Friend.

Iron ore pellets ar in general good behaved materials.

The angle of repose is in general 32 degrees.

density 2.6

composition varies .

in general lime , and dolomite some alumina can be found in them.

depending what are they for.

Direct reduction or blast furnace .

What source are your pellets.

The local suppliers can give you all kind of data . like percentaje of fines and internal friction angles.

Can you elaborate on your paper, maybe we can help you out.

Regards

Marco

Try a searc on

LKV or

CVRD ■

let me see if this helps.

the way pellets perform in storage means how they move ?

Iron ore pellets in open flat bottom storage form a conical flow channell.

This chanell depends on your internal friction angle, now if you want to trace the movements of the pellets , you are in for a good challenge .

the center goes as youw might guess faster, in what is known as funnel flow, once the funnell brakes the surface the slope flows in small avalanches, this avalanche are severall pellets deep and can satr anywhere in the slope , so locating traces in the open surface will give you a large spread . as two mechanisms are present, the slope stability and the funnel flow .

Also segregation will play a role changing the friction angles , once you have a pile of small size the loading system , unless you are using a stacker, will result in segregation . the next point is time , if your stack is there for a large time , it can generate a hard crust.

Sand models and unexpanded poliurethane .5 mm pellets can give you an idea of how this flows .

Try not to use bidimensional models , but if you doo remenber that the material will wedge in the corners reducing the apparent Flow velocity

Good luck

Marco ■

Silva

unexpanded poliethilene spheres are used in all factories that manufacture poliethilene. Here is call expansor. Th spheres ara subsecuently heated and expanded into molds. This is the white very lighth isulation you find in almost all packings .

Locate any factory and ask them to give you some 20 kg of the stuff.

But you can also use millet, we used millet in a recent project to simulate iron ore, as far as the information required millet worked very well.

Cream of wheat is another choice,

coloring is done with vegetable tints available for cakes and food stuf. use very little and miix rapidly.using rubber gloves.

Good luck

marco.

And please hurry , experimental prjects thend to be more elaborate than what is seen from the star point, also your customer , once ist stars to see results he can correlate , will ask for more. ■

Dear Silva,

You have not told of:

1. type of reclaim system - surface wheel or underground slots?

2. need to blend material in storage pile?

3. size and configuration of pellets and fines together with moisture that alter storage and reclaim behavior?

4. cohesive and adhesive strength loci ( J & J ) with moisture of granular field and if segragation is to be considered in documenting behavior of flow?

5. tracers to study pile size distribution?

6. tracers to study flow from pile and through reclaim method?

Sand prototypes can have variable flow behavior depending on whether they are:

1) river (round shapes) or, 2) crushed or broken rock (angular shapes).

Be careful that prototype material is free of static electricity buildup such as plastics.

You might consider using DEM to give some insight on the results and test program you wish to implement. DEM can give valuable information on how to structure a good test procedure. It can provide information of the above 6 points.

Lawrence Nordell

Conveyor Dynamics, Inc.

email: nordell@conveyor-dynamics.com ■

Dear Silva,

The angle of repose of pellet is ranginging from 26 to a max. of 30 deg.& its bulk density is 1.8 - 2.0 t/cub. m. In this respect I suggest you to read a book By KURT MAYOR. About pellet you will get every thing in this book.

The compressive strength is 250 KG/Pellet & during storing by STACKER there is hardly few generation of fines. We build pellet pile height of about 10 M. Pellet is normally reclaim by Payloader or by Bucket wheel reclaimer.

For storage of pellet for long duration in a pile, then coating to be provided in the same.

The above information is applicable for fired pellet only.

Silva, write me exactly what you want to know?

Regards.

A.Banerjee ■

If you are reclaiming with an open wheel .

There are two types of wheel reclaimers . that i have known.

the mounted in a bridge and the mounted in a boom.

bridge mounted machines are normaly used for blending .

you see not only the material characteristics vary from suoplier to supplier , not the solids flow in open strorage , but the chemicall and plastic properties when subject to high temperature .

there are severall indexes to descrive the process performance of pellets ,

swelling index

wal to solid friction coefficient.

sticking index

melting point.

iron content

type and coposition of the gange

acid pellets

basic pellets

dolomitic pellets

lime based pellets

organic binded pellets .

internal friction angle ,

just to mention some.

by the way the bulk density of the Alzada CVRD and LKV pellet is 2,6 tons per cu mt

if I recall well. It might have changed now but you can check with them .

pellet flow in open storage , flows in avalanches .

the shape and height of the avalancge us ruled by severall factors being one of them the particle size , a second one is the form of hill buildup, and the percentahege of fines in the feed.

humidity content becomes importan in the zones with greater fines content.

shape of the reclaim front sometimes affects the height if the avalanche.

there is an old article on the fines distribution of fines in a fix-tripper formed hill , maybe one of the readers can send you a copy.

Jerry Johansen had some articles in this respect if I recall well.

he did extensive work for US Steel.

By the way how did you plan to validadte your modeling ?

Regards

Marco ■

by the way if you are going to use tracers . do not , repeat do not feed them with the stacker.

set them at a depth of 5 to 10 patricles ftrom the surface.

try not to distrurb the pile , use a ladder over the pile , do not step on the pile.

regards

marco ■

Dear Mr. Marco,

We often argru with the bulk density of pellet. LISCO / QASCO is getting pellet from CVRD & LKV also. The bulk density of pellet as stated by them is maximum 2.3 ton. cub. m . 2.6 t/cub.m is too high a figure. Kindly let us know the exact figure of the same.

Regards. ■

well for 25 years it was 2.6

It is simple to measure , get a 1 ltr plastic container and weigh it.

take 10 samples and average them , or get a 200 ltr drum fill it with pellets and weigh it.

1.8 tons per cu mts will be abouth the density of sponge iron , ( DRI) from 1.6 to 1.8 .

But If CVRD is giving you that number that number it is , they might have changed the average pellet diameter , that is all.

It is in the advantage of the pellet maler to reduce the average pellet size , you can increase production proportionaly to the cube of the diference of diameters. But that will give you more density ?

they might have increasd the internal porosity, or added lighter gangue .

a smaller pellet will have some effect in the pressure drop.

If your process can take the slight differential pressure increase (HYL and MIdrex ) procesess will have little problem with the diferential pressure , the fluidization factor in the cooling sections will be more afected and some reactors might experience shakeouts , from moderate to severe . but your metalization might improve , (Otherwise you need to improve your loading train.) and you might be able to increase production.

if your process is hot discharge you might not have noticed .

Internal friction angle will increase and wall to solid friction also.

be carefull with the sticking . and piroforicity .

either ask for precoated pellets or add an appropiate makup.

I might be obsoloete in my numbers as it is five years since I have been involved in steel making.

So, simple enough have your lellets characterized CVRD will do it by default. Just ask for the numbers.

Marco

I would use 2.6 as design factor anyway . ■

Hello Silva

(or should that be "Hi - Ho Silva"?)

For what it is worth, there is a steel plant at Saldanha here in RSA which has an iron ore pellet handling facility.

I was called to inspect it and found that:

The belts at 11 degrees were still too steep, and the pellets often tend to roll back and cause spillage

The chutes wore out extremely quickly and low transfers are mandatory. Cascades are required in storage bins

Some pellets stuck to overband tramp magnets and caused a huge mess

The behaviour of the pellets in the stockpile was a pleasure, as they flow nicely

Careful design of the reclaim system is required for the control of spillage

Good Luck

LSL Tekpro ■