Topic 6.1 Iron and Steel

3 Types of Metals

1. Ferrous

2. Nonferrous

3. Superalloys

Ferrous

based of iron

ex. steels & cast iron

Nonferrous

other metals that are not iron

• aluminum, magnesium, copper, nickel, etc.

Superalloys

combination of metals

Three classifications:

1. Iron-based

2. Nickel-based

3. Cobalt-based

Ore

Metals come from rocks in the ground called ____

Hematite

Main Iron Ore in production of iron and steel (Fe2O3).

Magnetite (Fe3O4)

Siderite (FeCO3)

Limonite (Fe2O3 - xH2O ; x ≈1.5)

other iron ores

raw materials of Steel production

• Iron Ore/Hematite

• Limestone

• Coke (Carbon)

Iron Making

Iron reduced from its ores

Steel Making

Iron refined to obtain desired purity and composition (alloying)

Alloying

• adding metals together

• more than one metal/element

Steel

Iron-Carbon alloy

• contains 0.02% to 2.1% carbon

Cast Iron

an iron-carbon alloy containing from 2.1% to about 4% or 5%

carbon

Iron Ore

• rock containing iron combined with oxygen (iron oxide)

• Iron ores contain from 50% to around 70% iron, depending on grade (hematite is almost 70% iron).

• Scrap iron and steel are also widely used today as raw materials in iron- and steel making.

Coke

• supplies heat for chemical reactions

• produces carbon monoxide (CO) to reduce iron ore

• during this process, coke is produced

other Raw materials in Iron Making

• Coke

• Hot Gases (CO, H2, CO2, H2O, N2, O2, and fuels)

• Flux

Flux

• minerals used to collect impurities

• causes a chemical reaction to collect elements/impurities to form slag

Blast Furnace

• refractory-lined chamber with a diameter of about 9 to 11mm at its widest and a height of 40m

What is Coke made from?

Coal

Step 1 of Blast Furnace

Charging the Blast Furnace

(1) Charging the blast furnace

• happens at the top of the furnace

• raw iron is blended with other ore

• iron, limestone, coke, scrap metal feed

• hot air blown through nozzles

• oxygen reacts with CO2 and pure iron

Step 2 of Blast Furnace

Separating the iron from the slag

(2) Separating the iron from the slag

• melted iron sinks to the bottom of furnace

• limestone combines with the rock & other impurities to form slag

• slag is lighter than iron and floats on top

• drawn off the iron and slag separately from the bottom

• casting iron into an alloy called pigs iron

Step 3 of Blast Furnace

Treating the gases

(3) Treating the gases

• Hot gases produced in the chemical reactions raise to the top of the furnace

• Gas treating plant to clean the gas

• Carbon monoxide is useful for chemical reactions

Products and By-products of Blast Furnace

• Molten Iron (Product)

• Molten Slag (Byproduct)

Reducing agent

Carbon Monoxide (from Coke) is the reducing agent

• reduces Iron Ore to Iron

• Carbon is above Iron in Reactivity series

Impurities taken from Hematite/Iron Ore

Silica - sand, soil, rock, etc.

Slag

Calcium Silicate (CaSiO3)

Cast Iron

• cheap and easily moulded

• used for drainpipes, engine blocks

Pig Iron

• Pig iron is raw iron in an ingot form.

• It is a hard but brittle mix of iron (90% or more) and carbon (typically 4-5%), manganese, sulphur, phosphorus, and silicon (roughly 3% in total).

How is Pig Iron made

• Special rail cars bring the Molten Iron away

• The liquid iron typically flows into a channel and indentations in a bed of sand then cooled

Why is it called Pig Iron

• The name is derived from the time when the iron ran into moulds. A row of moulds was said to resemble a litter of suckling pigs, so the single ingots were referred to as pigs.

To create a Ton of Pig Iron

We start with

• 2 tons of ore,

• 1 ton of coke and

• ½ ton of limestone

• The fire consumes 5 tons of air

• The temperature reaches almost 1600 degrees C at the core of the blast furnace