Chapter 14.2 Extraction of Iron Flashcards
What does charge have
chemical formula
Iron ore + Limestone + Coke
Fe2O3 + CaCO3 + C
What is coke
Made of coal and is almost pure carbon
What is stage 1 of the extraction of iron
oxidation or reduction?
Endo or exo - why?
Chemical eqn
Coke burns giving carbon dioxide and heat
Carbon + oxygen —> Carbon dioxide
C (g) + O2 (g) —> CO2 (g)
Oxidation
Exothermic - heat given out heats the furnace
What is stage 2 of the extraction of iron
oxidation or reduction
endo or exo - why?
Carbon dioxide is reduced to carbon monoxide
Carbon + Carbon dioxide –> Carbon Monoxide
C (s) + CO2 (g) —> 2CO (g)
Reduction
Endothermic - lowers temp for stage 3
What is stage 3 of the extraction of iron
oxidation or reduction
endo or exo - why?
Carbon monoxide reduces the iron (III) oxide to iron
stage where the extraction happens and the iron trickles down to the bottom of the furnace
Iron (III) Oxide + Carbon Monoxide —> Iron + Carbon Dioxide
Fe2O3 (s) + 3CO (g) —> 2Fe (l) + 3Co2 (g)
Iron (III) oxide is reduced
Carbon monoxide is the reducing agent
Carbon monoxide oxidized to carbon dioxide
What is stage 4 of the extraction of iron
Part 1 - what happens, word eqn, chem eqn
part 2 - what happens, word eqn, chem eqn, is it a salt
Impurities are removed as slag
Thermal Decomposition: first limestone from the charge breaks down in the heat of the furnace
Calcium Carbonate –(heat)–> Calcium Oxide + Carbon Dioxide
CaCO3 (s) –(heat)–> CaO (s) + CO2 (g)
then
Calcium oxide reacts with sand:
Calcium oxide + Silicon (IV) oxide —> Calcium Silicate
CaO (s) + SiO2 (s) —> CaSiO3 (s)
CaO is a basic oxide
SiO2 is an acidic oxide
hence
CaSiO3 is a salt
What is the main impurity in iron ore
chemical formula
Sand - Silicon (IV) Oxide
What is slag
What happens to it
Calcium Silicate ( CaSiO3) - Impurity
Trickles down after formation and floats on the iron (less dense)
It is drained off and then is sold after it solidifies for road building
What happens to the waste gases from the blast furnace
Hot Carbon dioxide + Nitrogen from the air exit from the top of the furnace. Heat is transferred from them to heat the incoming blast of air.
(Nitrogen from air because the oxygen in the air is all used up and reacts with the carbon. Only nitrogen gets left)
What is cast iron
properties
uses
Iron with high carbon content.
Hard but brittle
uses:
Canisters, Bottled gasses, drain covers, etc. Not much stress applied on them
What happens to the iron after extraction
Turned into:
cast iron
steels (usually steels)
iron obtained from the blast furnace is contaminated with what
what removes it
what is also added to remove oxides of phosphorus and silicon
what is the nature of this substance
carbon
oxygen
calcium oxide
basic oxide
Which substance is not involved in the extraction of iron from hematite?
nitrogen
Why must the high levels of carbon be lowered before the iron becomes a useful material?
high lvls of carbon make iron too brittle
How is the excess carbon removed from the iron?
reacted with oxygen / oxygen blown in
