Chapter 12

Question 1

Do pure iron exist in nature?

Answer 1

Nope

Question 3

Where are iron ores concentrated in the US?

Answer 3

Midwest and Southeast

But mostly in mines in the Great Lakes.

Question 4

What does hematite look like as a compound?

Answer 4

Fe2O3

Question 5

What does magnetite look like as a compound?

Answer 5

Fe3O4

Question 6

As iron ore reserves shrink, what do we rely on for iron?

Answer 6

Taconite: siliceous rock containing fairly low-volume concentrtions of iron.

Question 7

How do they extract taconite and what do they do to lighten the load for shippment?

What’s the final percentage?

Answer 7

They strip mine and crush it, separate the iron-rich stuff with floatation, and sinter then into 0.5 in diameter balls (AKA pelletizing).

The balls have about 70% iron

Question 8

Why are steels mills typically on water ways?

Answer 8

Because ore is usually transported via “ore boats”.

Question 9

What is the first step of making steel after extraction and shippment to the mill?

Answer 9

Blast Furnace: impure ore, limestone (to remove phosphourous), and coke are poured into top and come out pure on the bottom with continous temp in furnace.

Question 10

Iron ore cannot be formed into a metallic iron until the _ _ _ _ _ _ _ is removed.

Answer 10

Oxygen!

Question 11

What is the fourth hidden ingredient in a blast furnace?

Answer 11

Air! It is used as oxygen for combustion of coke, as well as reduction of the iron oxide.

Question 12

Production of reducing gas equations:

Answer 12

1) C (coke) + O2 (air) –> CO2 (carbon dioxide)
2) CO2 +C (excess coke) –> 2CO (carbon monoxide)

Question 13

Reduction of the iron oxide:

they’re concurrent!

Answer 13

3a) 2Fe2O3 (ore) + 3C (coke) –> 4Fe + 3CO2
3b) Fe2O3 + 3CO –> 2Fe + 3CO2

Question 14

Which product of air and coke help to reduce oxygen from ore: CO or CO2?

Answer 14

Both! They each have their own equaiton but both help make pure iron from iron oxide.

Question 15

What is the name of the iron that comes out of the blast furnace?

Answer 15

Pig Iron! It has a high carbon content (v brittle)

Question 16

What can the slag be used for after the blast furnace phase?

Answer 16

Earth fill or concrete aggregate.

Question 17

What are direct reduction processes (DRI)?

Answer 17

New and improved ways of doing what the bals furnace does:
1) Iron ore + coal + oxygen in single melting vessel go directly into ingots or continuous casting machine.
2) Iron Carbide: reacts iron ore with methane and hydrogen to make iron carbide, then to BOF to remove excess carbon.

Question 18

What’s the problem wit hrecycling steels?

Answer 18

The more recycling, the more impurities in the steel.

Mostly copper, antimony, and tin.

Question 19

What do minimills do?

Answer 19

Add fresh virign iron to recycled to help with impurities.

Question 20

What percent of carbon does a carbon iron alloy need to be below to be considered pure iron? (at room temp)

Answer 20

0.005% carbon

Question 21

Why is the 2% cutoff for carbon content called cast iron?

Answer 21

Because the only useful way to use something so brittle is by casting.

Question 22

From a commercial standpoint, steels have a low carbon limit of what percentage?

What ‘s the whole steel range?

Answer 22

0.06%

0.06% to 2.0%

Question 23

What is the carbon content range of pig iron?

Answer 23

4% to 5%

But pig iron also has a bunch of things not in steel! (Si, S, P, Mn)

Question 24

What are the 2 types of steel refining?

Answer 24

Basic Oxygen Furnace (BOF) and Electric Arc Furnae (EAF).

Question 25

What year was the last open-hearth furnace (in the US) decommissioned?

Answer 25

1991

Question 26

Though BOF and EAF are smaller in size (<350 tons) then open-hearth (450 tons), why are BOF and EAF used more?

Answer 26

The open-hearth would take 10 kWh to do a job that would take the BOF 20 minutes to do :/ "more economical"

Question 27

Why not ingot anymore?

Answer 27

Continuous casting skips ingot step. | Make steel --> **tundish** (intermed reservoir) --> "continuous mold"

Question 28

Why can minimills be built anywhere while integrated mills have to be by waterways?

Answer 28

Bc do recycled steel and dont need imported iron ore or even have big blast furnaces

Question 29

Is recycling steel still uncool?

Answer 29

Nah fam! It used to be uncool and only used for barbded wire and highway guard rails, but now it's the "norm"!

Question 30

What is the Bessemer Converter? How does it work? Around when did it decline?

Answer 30

First model of BOF! It purified steel by blowing air through a vessel filled with molten iron to reduce carbon and make steel. Replaced by 1870 open hearth by 1910 until 1960 when BOF and EAF took over.

Question 31

What is the difference between the Bessemer Converter and the BOF?

Answer 31

The BOF is lined with refractory material that can be tipped to pour.

Question 32

What is the BOF process?

Answer 32

Scrap, pig iron flux agents, and moltent pig iron melt together and oxygen enters (w/ argon sometimesto help) to reduce C, S, and P. Steel pours, cover refractory in nitrogen spray to prevent lining wear, alloy additions in laddle outside of BOF, and sometimes sent to **vaccuum degassing** for further refining.

Question 33

What is the specialty of EAFs?

Answer 33

They can be turned on and off (don't have to stay hot to melt stuff).

Question 34

Secondary steel-making processes are done in the _ _ _ _ _ _.

Answer 34

Laddle

Question 35

What is an example of a secondary steel making process?

Answer 35

Vaccuum degassing: uses argon and oxygen to remove impurities. | Kew word: deoxidization