materials processing: ore refining

For blast iron furnace making, name the three material inputs

iron ore, limestone, coke

For a blast furnace, name the two material outputs

liquid pig iron, slag

what is the reducing agent in chemical reactions for a blast furnace

carbon monoxide

why is coke used instead of coal?

it has a higher % of carbon, more porous (more surface area)

how is a blast furnace heated

preheated pressurized air blown at bottom

____ is used to capture impurities to help purify and generate liquid pig iron, like ____ and _____

slag, silicon dioxide and sulfur

which is put in a blast iron furnace first, scrap or pig iron?

scrap

What is the main difference between steel and pig iron that necessitates BOF processing?

pig iron has 4%C, steel has 2%C

Which process is most commonly used to make intermediate solid forms from the molten steel produced by the basic oxygen furnace (BOF)?

continuous casting

The main products of the continuous caster are

• _____ (square or round sections up to 150 mm)

• _____ (square or round sections >150 mm)

• _____ (>600 mm by >40 mm)

billets, blooms, slabs

when refining aluminum metal, what is reduced at the cathode and what is oxidized at the anode?

aluminum gains e- (reduced) and oxygen loses e- (oxidized)

The microstructure of a plain carbon steel consists of ___________ and _____

proeutectoid ferrite and pearlite

it is a two-phase lamellar (parallel layers) mixture of ferrite and iron carbide (Fe3C).

pearlite

a blast furnace makes ______, not ______

pig iron, steel

what furnaces can steel be made in?

BOF and EAF

does EAF turn pig iron into steel?

no, only uses scraps

The steps in the Bayer process include _____ → _____ → _____ → _____

digestion, clarification, precipitation, calcination

what is the starting ore used in the bayer process?

bauxite

what is aluminum metal refined from?

aluminum oxide

what is the voltage needed for aluminum refining?

3-5V

low carbon steels use less that ___ %C

0.2%C

medium carbon steels use between ___ %C and ____ %C

0.2%C and 0.5%C

high carbon steels use between ___ %C and ____ %C

0.5%C and 2%C

Precipitation hardening in aluminum alloys

A=solutionising, B=quenching

Overaging occurs due to ________

precipitate growth

what does the clarification of bauxite produce?

red mud

what are the primary components of slag? and from which materials are they from?

SiO2 from iron ore and CaO from limestone

Aluminum oxide needs to be dissolved in ______ to reduce the melting temperature during refinement

cryolite

for a basic oxygen furnace (BOF), what are the primary material inputs?

pig iron, scrap steel

for a BOF, what are the primary material outputs?

liquid steel, slag

alloying elements are added into the BOF after the ___ stage, why?

blow, more reactive than iron and will be lost in slag

molds for steel ingots are made of _______ iron

high carbon

introduces atom-size obstacles to molecular motion

solution hardening

Cr content in stainless steels is normally above ___%

12

yield losses in fabrication depend on required change in _____ from stock to finished product

geometry

_____ is added to flux the removal of impurities such as SiO2, sulfur, and Al2O

limestone (CaCO3)

A=2FeO, B=Fe

what are the seven end of life alternatives for manufactured goods?

Reuse, refurbish, upgrade, recycle, downcycle, combust, landfill

In _____, a new purpose for contaminated material is found instead of reusing for its original purpose, only delaying the end of life. On the other hand, _____ doesn’t degrade the properties of the product after repeated life cycles

downcycling, recycling

liquid pig iron is more/less dense than slag?

more

what is the function of the double bell system in a blast furnace?

minimize escape of gases and dust

pig iron contains over ___%C

4

A cupola furnace converts _____ to ____

pig iron, gray cast iron

horizontal line connecting the intersections of the solidus and solvus lines from both sides

eutectic line

cycle time of a basic oxygen furnace is approximately ___ minutes

45

Out of CO, CO2, and CO3, which of the two are removed as gases during the BOF process?

CO and CO2

cycle time of an electric arc furnace (EAF) ranges from ___-___ hours

1-4

Compared to a BOF, EAF produces _____ but is ____

better quality steel, more expensive per ton

During continuous casting, molten metal is poured into a _____ and then into a water-cooled mold → solidifies as it travels down in the mold

tundish

Austenite has ___ crystal structure

Ferrite has ____ crystal structure

Cementite (or iron carbide) has an _____ crystal structure

FCC, BCC, orthorhombic

Low-carbon steel has high ____ while high-carbon steel has high _____

ductility, strength

Low alloy steels are not easily welded at ____ and _____ carbon contents because of martensite formation

medium and high

Why do we alloy iron instead of using just pure iron?

pure iron has very low strength

slip plane becomes stepped and threaded with ‘forest’ dislocations

work hardening

presents larger dislocation obstacles

precipitation hardening

only resistance is the intrinsic strength of the crystal

perfect

low alloy steels often require ____ for their properties to be realized

heat treatment

tool steels are ____ carbon and ____ alloy, usually containing what 4 alloys?

high, high, chromium, vanadium, tungsten, and molybdenum

Austenitic Stainless steels: Usually ___% Cr and ___%Ni . Nickel stabilizes austenite at room temperature. Low carbon, very ductile. Used in chemical and food industries, etc

18,8

Ferritic stainless steels: ___ to ___% Cr, no nickel, low carbon. Used for many applications, from kitchen utensils to jet engines

15 to 20

austenitic SS is ___ corrosion resistant than ferritic SS

more

The ____ process refines aluminum oxide from bauxite and then aluminum oxide is smelted to aluminum using the _______ process

bayer, hall-heroult

Fill in the blank for EAF flow diagram

A=close furnace by replacing cover

B=tap liquid steel into ladle

fill in the blanks for the bayer process

A=wash and crush bauxite

B=purified Al2O3 product

Low alloy steel is a carbon steel containing additional alloying elements with a total less than __ wt%.

5

What is the process that produces titanium metal?

Kroll

What is the byproduct of the Kroll process that needs to be removed after titanium metal is produced?

magnesium chloride

Which process is more sensitive to the composition of scrap steel added, EAF or BOF?

EAF

Which is more commonly used to convert pig iron into steel, BOF or EAF?

BOF

What is the reducing agent is used in the Kroll process to produce titanium metal?

magnesium

fill in the blank for the BOF process

A=add fluxes to furnace

B=tap slag from furnace