Scrap Metals Supplement--Cleaning Up

In North America, Hydro Aluminum NA is one of several aluminum producers competing for aluminum scrap. The company has been focusing research and technology efforts on ways to use additional scrap grades—such as forms of obsolete aluminum scrap—in the production of higher-end finished aluminum products.

"Our challenge as an industry is to dig deeper into the scrap supply and use it effectively," the company’s Lynn Brown told attendees of the Aluminum Roundtable at the 2004 ISRI Commodity Forum, held in September in Chicago.

When industrial production slumped in the United States in 2001 and 2002, aluminum scrap consumers began counting on auto shredder scrap and demolition scrap as two sources to replace the lack of plant stampings and trimmings.

Purifying and using aluminum scrap from the obsolete stream could be an important new challenge for scrap processors and consumers if the volume of clean scrap trimmings remains restricted.

THE SQUEEZE IS ON. Among the most desirable grades of scrap sought by some consumers are prompt grades produced during the extrusion process. Brown says that, fundamentally, "What everyone would like to have for remelt operations is clean process scrap from extrusion plants."

Brown says of such factory-generated grades of scrap: "They are nicely segregated by alloys, clean, easy to handle, and the logistics of collecting and processing them are fairly easy."

On the plus side, extrusion is a process that, relative to some other forms of metalworking, generates a lot of scrap. Brown estimates extruders generate anywhere from 18 percent to 28 percent scrap at their presses.

This generation occurs as heated billets are pushed through shaping dies and then as the extruded shapes are clamped to be stretched. The shape of the extrusion is ruined at the clamped ends, so these ends are trimmed and scrapped. "The nature of the operation is such that even our best operations probably only use 82 percent of the metal," notes Brown.

But even this steady production of extrusion scrap goes only a short way toward providing scrap needed as feedstock by remelt furnace operators. Brown says that if a remelt operator wants to produce new billets for one of ifs extrusion customers, that same customer’s scrap produces only about one-third of the scrap material needed.

"If you want to produce a billet that is 75 percent scrap and 25 percent primary aluminum, but you only get one-quarter of the prior billet back, you have to fill that gap," says Brown.

PROBLEMS TO BE SOLVED. The need for a large volume of scrap to feed a scrap-dependent production process is not unique to aluminum remelters. Steel mills using the electric arc furnace (EAF) method have long had to explore how to use a broad range of ferrous scrap grades in their processes.

The development of auto shredding plants and their downstream separating systems have gone a long way toward filling the ferrous scrap demand of EAF steelmakers by digging into the obsolete scrap stream.

Shredding plants produce grades of aluminum scrap as well, but most remelt operators are not able to use the mixed-alloy "twitch" grade produced through this process.

Several barriers restrict the grades remelt operators can use:

• Molten aluminum is much more volatile than molten steel, so some contaminants do more than spoil the chemistry. Some are categorized as "volatiles," meaning they can cause explosions at
the remelt plant.

• Emissions at remelt shops are being closely monitored with the enactment of the maximum achievable control technology (MACT) requirements is sued and revised by the U.S. EPA
earlier this decade. The presence of paint on scrap can be a particular dilemma from this respect.

• Even if volatiles can be avoided and emissions standards met, it is still important to meet narrow chemistry speci-
fications to produce the precise alloy demanded by customers.

CAPITAL IDEAS. If remelt operators wish to broaden their scrap range, they are thus faced with several investment and spending scenarios.