Design of 2500 t Steel Bin for Iron Ore

Posted in: , on 11. Aug. 2010 - 22:55

Design of Cylinder and Cone junction of 2500t Steel Bin for Iron Ore

One of our project involves design of a large steel bin of 11m diameter for Iron Ore storage.The height of barrel (cylinder) is only about 6.5m and the cone is about 22m.The weight of stored material is 2500t.The ring girder of bin is proposed to be supported on on eight columns provided on the periphery of a square.

I would like to know weather a welded joint of cone with the skirt(web of ring girder) would be sufficient for such a big load at the junction (transition) of the cylider and cone.

What special care is to be taken in terms of weld quality, its inspection and tests ?

Should additional supports be considered at cone ?


Re: Design Of 2500 T Steel Bin For Iron Ore

Posted on 11. Aug. 2010 - 11:06

If you don't have the skills then employ a designer with a proven record in silo design, don't rely on web sites.

The last thing you want is having to explain to your boss why there's 2500 te on the floor

Re: Design Of 2500 T Steel Bin For Iron Ore

Posted on 12. Aug. 2010 - 03:36

Thanks for your reply.

We do have structural engineers with experience. As the bin is quite big I want to know what are other possibilities and practices for ensuring a sound joint at the transition of cylinder and hopper cone.

The cylinder of bin is on vertical ring girder and cone is connected to its web.The

girder is supported on eight columns.The capacity of 2500t is the requirement.


Bin Design

Posted on 12. Aug. 2010 - 03:00

The basic specificationis interesting as it indicates that the minimum inclination of the cone angle will be at least 76 degrees to the horizontal, which implies a Mass Flow construction to deal with a poor flow bulk condition of the ore. If the ore is not free flowing, the proportion of the cylindrical portion would seem barely adequate to give wall contact from a central fill, so the 'kick' pressure normally associated with mass flow will be neglible and the hoop stress in the bulk very low, particully given the velocity gradient that will be generated in the conical portion, at least relieving the hip joint of serious flow and wall pressure stresses.

As virtually the total weight of the bin and contents will be carried by the shell at the hip joint, I would have thought it easy to calculate the stress on the 34.5 metre circumfence of the welded joint and most likely find it to be high in relation to the bin wall thickness. In any case, the cost of a number of ribs would be trivial in this general construction.

However, it is presumed that this flow regime has been selected on the basis of material tests indicating the outlet size and wall angle necessary for reliable discharge, rather than a for a first-in, first-out requirement of an inert material. One may therefore query the basic design concept and whether an expanded flow construction would be more appropriate, with the transition at a diameter larger than the critical rathole size and using a self-clearing inclination on the upper cone section to reduce wear on the main storage region.


Posted on 13. Aug. 2010 - 04:10

Dear Mr.Bates

Thank you for your views.

Doubtless the hip joint at transition is the only support for the entire load of filled up material and cone self weight.I would appreciate if I get the typical welding detail at the joint for such a connection of vertical plate and inclined plate of cone.What precautions should be taken during fabrication for making such a joint and what tests should be conducted to ensure quality of the weld?



Hip Joint

Posted on 13. Aug. 2010 - 10:15

This is a big silo and carrying a heavy load on the hip. Support from the ring beam and connection to the cone requires a thorough structural analysis. Standard welding proceedure would apply to the joint, according to the thickness of plate adopted, but lap plates or vertical rib supplementary support can be given if required. Having in this case discounted additional stresses due to flow behaviour, the situation reduces to a structural engineering problem and I suggest that basic engineering design and workshop practice are beyond the scope of this forum as they are craft, rather than bulk technology issues.