Page 107 from: May 2008

May 2008 107

S h r e d d e d S c r a p

In addition, when mixed with other feedstock,

the shredded scrap fi lls the voids to provide a

more dense mix. Also, shredded scrap lends

itself to better material handling techniques.

One of the disadvantages of shredded scrap is

that it contains tramp elements such as copper.

For EAF steelmakers to become more effi –

cient, more shredded will be used while the

cost of shredding will be reduced through use

of larger, tougher shredders. Furthermore,

more scrap sold by the processor to the con-

sumer will have been blended for charging

purposes. Over the last seven years, more

material has been blended at steel mills which

buy their specifi cation scrap through out-

sourced contractors like Tube City.

Forward-looking processors
A number of forward-looking scrap processors

are selling blended steel scrap to consumers.

Traditionally, the steel mill has blended differ-

ent grades of scrap steel to provide the lowest

cost raw material to satisfy melters’ require-

ments. The melter obtains exactly the blend

required for the product to be produced; in

this way, he does not pay for better grades of

scrap than required or spend a lot of time

diluting/refi ning the molten steel. However,

the emerging view is that it is less expensive to

perform the blending process at the scrap

facility such that, when the material arrives at

the steel mill, it can be fed directly from the

rail car or delivery truck into the charging

bucket. The scrap processor may even guar-

antee the chemical composition by offering to

pay any lost melt costs.

Delivery of the correct blend of scrap to the

furnace eliminates several process steps and

achieves savings that can be divided between

the scrap processor and the steel mill.

Scrap processors are also attempting to fi nd

ways to reduce mounting freight costs. One

option is to increase the density of the scrap

steel to boost the amount of material that can

be carried in each rail car or truck. It is also

possible to: arrange with steel mills to accept

deliveries in dump trucks on a 24-hour basis

to avoid traffi c peaks; and to negotiate with

railroad companies to use unit trains to move

large amounts of scrap at one time. For exam-

ple, if 10 rail cars can be covered by the same

bill of lading, these can be picked up and

delivered simultaneously using the same rail

crew. The cost of delivering the 10 rail cars is

about the same as for one rail car.

Copper residuals and cooling scrap
With the new designs of shredder, it is possi-

ble to produce shredded steel scrap with lower

copper residuals, thereby adding value to the

product. This is achieved by selecting the

materials to be shredded or by size separating

the shredded steel scrap so that the lower cop-

per residual materials can be sold separately.

This material normally sells for a premium of

US$ 7-20 per tonne over normal shredded

steel scrap.

Cooling scrap also attracts premium prices

and is introduced into molten steel to cool it

to the proper temperature for use in the con-

tinuous casting machine. The modern shred-

der has major potential to produce cooling

scrap because of its ability to process heavy

scrap into a very dense product.

Also envisaged are further improvements in

the separation of non-ferrous metals from

the waste material. New separation systems

allow a much better recovery of non-ferrous

metals because of tremendously improved

recovery of the ‘fi nes’ and better techniques

for recovery of small copper wires which

could not be recovered in the past.

The author of this
article, Scott Newell,
is President of The
Shredder Company,
LLC, based in
Canutillo, Texas, USA.
Mr Newell has been
operating and building shredding equip-
ment since 1959. He can
be reached at e-mail: theshredderco@the

shredderco.com

www.theshredderco.com

Continuous feeding
It is our belief that shredded steel scrap will

be continuously fed into EAFs in much the

same way that directly reduced iron ore pel-

lets are introduced to the furnace through a

fi fth hole in the roof of the furnace.

A number of benefi ts await the operator who is

able to solve handling problems. For example:

• Tap-to-tap times should be reduced because

less time will be spent with the roof off the

furnace.

• Total energy used to melt each tonne of

material should be lower through heat con-

servation resulting from leaving the roof in

place longer.

• It should be possible to pre-heat the scrap

with exhaust gases, thereby further reducing

energy requirements.

To achieve this, shredded steel scrap must be of

suffi ciently uniform size to fl ow smoothly out

of hoppers, which usually means that it must be

dense enough to make the pieces uniform. We

believe this is achievable at about 120 pounds

per cubic foot (1.85 tonnes per cubic metre).

In conclusion
The scrap processing and steelmaking indus-

tries are really one industry which will become

ever more effi cient through reducing costs and

adding value. We will shred more of the scrap

steel used in steelmaking, and we will shred it

more effi ciently in larger, tougher and smarter

machines. We will create more types of shred-

ded steel scrap that will have higher values, such

as low copper residual scrap, cooling scrap and

higher-density special grades.

All of us will learn to eliminate steps in the pro-

cess, thereby reducing handling and freight

costs. We will learn how to blend a more value-

added package of scrap for use in the EAF. And

we will learn how to use steel scrap in our fur-

naces in a more effi cient manner.

Adams Steel’s downstream system.Super Double-Feed Roller System.

RI_061_Shredded Scrap.indd 5 14-05-2008 14:04:45