The use of turnings and
borings varies from mill to mill, depending on the melter's
experience and preference. But for all mills, chemistry is
Some mills might use only a small
fraction in their melt, or they'll specify alloy-free turnings
in the scrap purchased from outside suppliers. Still others
have different ways of buying, storing and charging turnings
and borings into their electric-arc furnaces.
There are two different types of
briquetting. One is specifically for borings, while the other
can be used for combinations of borings and turnings. Hot
briquettes are made at Ferrous Processing & Trading Co.'s
Zalev yard in Windsor, Ontario. Louis Padnos Iron & Steel
Co. also makes both hot and cold briquettes at its facility in
Holland, Mich. Many more scrapyards and industrial plants make
the cold-pressed briquettes.
Some melters prefer the hot briquette
over the colder puck because it has better physical properties,
holds together much better and is a more robust product,
travels better and doesn't disintegrate and fall apart as
easily as the cold briquette. But many of the cold briquettes
are made at steel mills and, thus, don't have far to go to the
What they give up with the hot
briquetting process is some part of the carbon, one scrap buyer
said. It is oxidized in the process, so while loose borings
typically have a 2- or 2.5-percent carbon content, hot
briquettes of borings range from 1.9- to 2-percent carbon.
"That's one of the key reasons we melt borings," he said. "We
are after the carbon."
What separates iron from steel is the
carbon level. Borings come from cast iron, so typically they
are 2.5 percent or higher in carbon than steel turnings. By
using the more carbon-rich borings, mills hope to reduce some
of the charge carbon that must be added to meet specifications.
Also, the carbon combines with oxygen and creates energy, thus
saving the melt shop a little on its fuel wattage
But borings and turnings in loose form
are lower yielding, according to Rob Whistle, purchasing
manager at Gerdau Ameristeel Corp.'s recycling division in
Whitby, Ontario. "The melters gain some advantages with the
briquette, but it is just minimal. It is nothing like what the
scrap dealers suggest," he said.
Not all steelmakers and scrap
processors are fond of hot briquettes. Some, like Fort Wayne,
Ind.-based Steel Dynamics Inc. (SDI), use cold briquettes, and
avoid the problem of keeping the hockey puck-sized briquettes
from falling apart by using a binder to hold the material
Some mini-mills used to be big users of
both briquetted borings and turnings and loose turnings, but
have cut back consumption of those grades. In some instances
last year, better industrial steel scrap grades like No. 1
bundles and No. 1 bushelings were available at lower prices
while some briquetters were being offered higher prices for
Where were those turnings and borings
going? The dealers found homes among mills in the United
States, where some paid prices that were close to those of
plate and structural scrap. Plate and structural scrap normally
commands a premium of at least $10 per long ton over No. 1
heavy melting steel and a $50-per-ton premium over the more
common grades of turnings and borings.
But the idea of marketing briquettes as
a plate and structural scrap substitute doesn't make much sense
to Whistle and other scrap buyers.
"The chemistry is still just mixed
machine shop turnings, so you are never sure what the chemistry
is in those briquettes," one Ohio-based scrap buyer said.
One explanation for the price spike was
an apparent short supply of turnings and borings, one SDI
manager said. "The manufacturing economy got so slow that the
output of turnings and borings was way down. Most of the
turnings SDI uses come from industrial plants like screw and
Gerdau Ameristeel stopped using
briquettes and sacrificed the density its melters desired. The
primary benefit of using briquettes at its Canadian mills was
the density, particularly at the Cambridge, Ontario, operation,
where it has a small 50-ton-per-heat electric-arc furnace.
But for all the mills, chemistry is the
most critical problem. SDI uses turnings and borings only at
its bar-making plant in Pittston, Ind., and not at its
flat-rolled mills. Still, it carefully separates the turnings
and borings into bins that represent different dealers and
industrial sources. Others, like ArcelorMittal's mill in
Coatesville, Pa., have been doing the same for years. Both
mills have separate bins in the mill scrapyard and a clear idea
of the chemistries in each bin.
Moisture content is less of a problem.
When turnings and borings are sitting in a dealer's yard the
cutting fluids drain off or evaporate. Also, some scrapyards
have installed large centrifuges that further dry out the
turnings and borings.
Moisture is often more of a problem at
some industrial plants and might be as high as 5 or 6 percent
of the weight in the collection hopper. That's where the
economics of a smaller briquetting machine can make a
difference, Whistle said, noting that a wise scrap dealer will
explain to the plant manager that they should put in a small
briquetter. First, the plant can recapture and possibly reuse
some of the cutting fluids; second, the turnings and borings
will be worth more because the scrap dealer will reduce the
discount for moisture in each load; and lastly are the
idiosyncratic decisions that melters make for charging turnings
and borings into the furnace. Some that use loose turnings put
them at the bottom of the charge bucket to serve as a cushion
and protect bottom refractories in the furnace. Still others
layer the charge and put the briquettes between two other
grades of heavier scrap. A few put the briquettes on the top of
the charge, but one scrap buyer said most melters avoid that
practice because the briquettes loosen up and the smaller
turnings can be blown out into the baghouse and start a
"That's a major reason why a lot of shops
turn away from turnings because there is a major potential for
that," one scrap buyer said.