Page 89 - MetalForming Magazine June/July 2022 80th Anniversary Issue
P. 89
Metal Matters
New production techniques for steel and aluminum rely on hydrogen rather than carbon to reduce iron oxide to iron and aluminum oxide to aluminum. Note: Shown here are the reactions; they are not chemically balanced equations.
IRON OXIDE
HYDROGEN
IRON OXIDE
ENERGY
ALUMINUM OXIDE
IRON WATER
C COAL
ALUMINUM OXYGEN
C
GRAPHITE
aluminum to supple- ment the recycled con- tent. Beverage cans have a relatively short turn- around time, unlike automotive aluminum where it may take sev- eral decades until that aluminum content becomes available for recycling. By 2035, some projections indicate that available automotive scrap will still meet less than 50 percent of demand.
Green Steel Production
Two production routes exist. One: inte- grated mills, which pro-
duce molten iron in a blast furnace (BF), followed by conversion of iron to steel in a basic oxygen furnace (BOF). An alternate approach is compact strip pro- duction (CSP), occurring in minimills that use an electric arc furnace (EAF) to melt primarily steel scrap. In the United States, the BF-BOF route represents 30 percent of production, with the remain- der EAF-CSP. In the rest of the world, the percentages essentially are reversed due to the relatively lower availability of scrap for melting. Even with BF-BOF, the BOF charge uses approximately 25- percent scrap in addition to the iron comingfromtheBF.
Scrap-based steel production requires substantially less energy and emits less carbon dioxide than the inte- grated approach that starts with taconite. Although some minimills melt nearly 100-percent scrap, the products they
IRON
CARBON
DIOXIDE
ALUMINUM OXIDE
ALUMINUM
CARBON DIOXIDE
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