Extraction of Zinc

Questions and Answers

What is the primary function of the haematite lining in the production of wrought iron from cast iron?

To produce iron at a higher temperature

To remove carbon impurities

To increase the blast furnace gas production

To remove impurities and produce iron simultaneously (correct)

What is the composition of blast furnace gas?

50% N2, 30% CO, 10% CO2 and 10% H2

60% N2, 20% CO, 10% CO2 and 10% H2

40% N2, 35% CO, 15% CO2 and 10% H2

58% N2, 25% CO, 10.5% CO2 and 6.5% H2 (correct)

What is the byproduct of iron extraction used for making cement?

Blast furnace gas

Pig iron

CaSiO3

Slag cement (correct)

What is the primary purpose of steel making?

To remove most of the carbon and other impurities from pig iron Signup and view all the answers

What is the reaction that produces slag?

MnO + SiO2 ® MnSiO3 Signup and view all the answers

What is the purpose of the blast furnace gas?

To preheat the air used and for cooking purpose Signup and view all the answers

What is the composition of slag?

CaSiO3 and little Al2(SiO3)3 Signup and view all the answers

What is the purpose of the reaction 3C + 2Fe2 O3 ® 2 Fe + 3CO -?

To remove carbon impurities from cast iron Signup and view all the answers

What is the significance of the reaction 3Si + 2Fe2 O3 ® 4Fe + 3SiO2?

It removes silicon impurities from cast iron Signup and view all the answers

What is the reaction that produces FePO4?

Fe2 O3 + P2 O5 ® 2 FePO4 Signup and view all the answers

Study Notes

Extraction of Zinc

Zinc ores: ZnS (Zinc blende), ZnO (Zincite), ZnO.Fe2O3 (Franklinite), ZnCO3 (Calamine), ZnSiO3 (Willemite), ZnSiO3.ZnO.H2O (Electric calamine)
Zinc blende (ZnS) is the chief ore used for extraction of zinc
Extraction process: Froth floatation, Roasting, Carbon reduction, Electrorefining
Froth floatation: Separates out PbS and ZnS based on their different floating characteristics
Roasting: Converts ZnS into ZnO
Carbon reduction: Reduces ZnO into Zn
Electrorefining: Purifies Zn using electrolysis

Electrorefining of Zinc

Electrolyte: ZnSO4 + H2SO4
Cathode: Al sheet
Anode: Impure Zn
Reactions:
- At the cathode: Zn2+ + 2e → Zn
- At the anode: Zn → Zn2+ + 2e
H2SO4 is added to increase the overvoltage of H+, ensuring deposition of only Zn2+ at the cathode

Extraction of Iron

Iron ores: Fe2O3 (Haematite), Fe3O4 (Magnetite), Fe2O3.3H2O (Brown haematite or limonite), FeCO3 (Siderite or spathic iron ore), FeS2 (Iron pyrite)
Haematite (Fe2O3) is the chief ore used for extraction of iron
Extraction process: Gravity separation, Roasting, Smelting
Roasting: Removes CO2, SO2, and converts Fe2O3 into Fe
Smelting: Reduces Fe2O3 into Fe using coke

Purification of Iron (Wrought Iron)

Process: Puddling process
Reactions:
- S + O2 → SO2
- C + O2 → CO2
- 3S + 2Fe2O3 → 4Fe + 3SO2
- 3Si + 2Fe2O3 → 4Fe + 3SiO2
- 3Mn + Fe2O3 → 2Fe + 3MnO
- MnO + SiO2 → MnSiO3 (slag)
- 3C + 2Fe2O3 → 2Fe + 3CO
Wrought iron contains less than 0.5% impurities, including Mn, Si, P, C, and S

Byproducts of Iron Extraction

Slag: Consists of CaSiO3 and Al2(SiO3)3, used for making cement
Blast furnace gas: 58% N2, 25% CO, 10.5% CO2, 6.5% H2, and hydrocarbons, used for preheating air and cooking

Description

This quiz covers the process of extracting zinc from its ores, including zinc blende, zincite, franklinite, and calamine. It also touches on the role of powdered anthracite and electrorefining in the extraction process.