Long-term storage solutions for bulk materials?

Posted in: , on 19. Sep. 2007 - 23:02

I am a new to bulk material handling engineering as I have just (about 8 months) been assigned to a bulk material system in a grout making process. The system employs 3 silos with a capacity of ~30000 cu. ft. yet no silo is filled past 50% due to geometry concerns. All silos are identical in geometry, yet they all contain a different material (Slag, Flyash, and Cement).

The system was designed and installed by a engineering/construction firm ~15 yrs old and is suffering from a host of problems. Our most concerning problem is our inability to recover from extended system shutdowns, ie periods great than one month. The problem we are experiencing is loss of flow in the slag silo. Once this has occured the bridges are broken by mechanical agitation. I've read countless times the best solution is to keep the material moving, this is not viable in my situation as my facility is a government owned nuclear facility and the process can be shutdown on whim for any amount of time.

Are there long term storing solutions or will compaction and cohesion always win out in these situations? Is there a certain technology that I can use to help? Any other suggestions please let me know or if I have been too vague in my description I'll be happy to answer any questions concerning the system.



Re: Long-Term Storage Solutions For Bulk Materials?

Posted on 21. Sep. 2007 - 05:06

Tell us more about the silo geometry.

Dia, height, cone angle, bottom opening size, discharge feeder type & size.

You are describing materials which like to absorb mositure from the air & consolidate in storage.

Many silos are built like hourglasses, great big diameter with tiny little opening at the bottom. Then people wonder why nothing comes out of it. I have made a decent living some years cutting open the silo bottoms with tiny openings & installing big mass flow screw feeders.

If you can recirculate material, ie discharge it then refill it you might be able to keep it active during extended shutdowns. (but at a great cost in energy)

RPD - Invista (UK) Ltd., U.K.
(not verified)

Re: Long-Term Storage Solutions For Bulk Materials?

Posted on 21. Sep. 2007 - 01:17

If you talk to a company who make vibratory bin dischargers, they may be able to offer you some equipment that you could retrofit.

I am surprised that you want to do that though, I assume that you are talking about grout for nuclear waste. I thought that for this sort of systems the nuclear industry had very tight controls on product quality.

My experience is that that for materials to make grout for this purpose there should be controls on the maximum shelf life of the materials, close controls to prevent segregation, etc.

For this application I would have thought you would want small mass flow silos to minimise segregation and to empty the silos at the end of each campaign.

Not to leave material in clearly poorly designed, large silos, with the increased risk of segregation, moisture absorbtion, characteristics changing with age, etc.......that worries me.

Silo Re-Design

Posted on 21. Sep. 2007 - 07:09

Hello Chris

We have pleasure in inviting you to browse through our website. It shall be our pleasure to work with you to work out a feasible solution for your problem. Please be so kind to send us the silo GA drg with it's associated equipments and a layout drg. We have done many such re-engineering projects for steel & RCC silos for the cement industry

Thanking you in advance and with bets regards from India

Anirban Bhattacharya Managing Director HP # +91-99-1025-8259 Frigate Teknologies Pvt Ltd E-Mail : office@frigate.in Web : www.frigate.in

Re: Long-Term Storage Solutions For Bulk Materials?

Posted on 21. Sep. 2007 - 10:05


Anytime materials are stored for an extended period of time, moisture, vibration, temperatures, etc. cause materials to pack and "bridge over" any typical opening in the silo.

We engineer, and manufacture fully automated mechanical reclaim systems designed to rotate 360 degrees in the bottom of silos to reclaim materials and deliver to your process on demand.

I will just need a more detailed description of the silo sizes, floor designs, desired discharge rates, and a description of the various materials being stored.


Re: Long-Term Storage Solutions For Bulk Materials?

Posted on 24. Sep. 2007 - 07:23

Hi Chris!

The BinEX rotary bin discharger sounds like it would be a perfect fit to your problem.

We have many installations in the cement industry handling flyash, slag and cement.

Please feel free to visit our website for more information or contact us at 705-749-3544.




Re: Long-Term Storage Solutions For Bulk Materials?

Posted on 24. Sep. 2007 - 08:18

First off thanks for everyone's help. I really appreciate the feedback.

JD - I made a rough sketch of the silos, I think I got all of the important dimensions. One thing that might be of interest, the very bottom cone has an air gap along the cone wall with a polyester membrane. I am thinking this is what might be causing my flyash to flow extremely, almost too well, fluidizing the material.

We are currently pursuing recirculation of the dry materials. The transfer line does a have diverter valve, intended for truck unloading, which would be ideal for this application, however we are trying to overcome safety concerns with the use of flexible hose for the transfer.

Each silo discharges into an airslide which feeds a weigh hopper where the dry materials are measured per the recipe. From the weigh hopper, the material enters 1 of 2 air blenders, and then pneumatically conveyed into another smaller holding silo.

RPD - You are correct this is a grout making process for nuclear waste or what we call 'saltstone'.


silobmh (JPG)

Dome Structures

Posted on 22. Dec. 2007 - 03:55

Hello Chris,

If you don't yet a solution, you can check our web site www.dome-structures.com or www.haring.ch, we have several solutions for bulk storage buildings and for example the dome solution can have +-200m diameter and +-60m height in the middle. It's possible to apply cranes in the roof structure.

The structure is in timber (glulam) and the fire resistence can be 30m, 60m or more. The hazard conditions of the storage material isn't normally a problem has you can see for example in one of the buildings done, the salt storage in Switzerland www.saldome.ch

I hope this could help you.

Best regards,

Sergio Lucas