Questions and Answers
What is the primary function of the haematite lining in the production of wrought iron from cast iron?
What is the composition of blast furnace gas?
What is the byproduct of iron extraction used for making cement?
What is the primary purpose of steel making?
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What is the reaction that produces slag?
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What is the purpose of the blast furnace gas?
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What is the composition of slag?
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What is the purpose of the reaction 3C + 2Fe2 O3 ® 2 Fe + 3CO -?
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What is the significance of the reaction 3Si + 2Fe2 O3 ® 4Fe + 3SiO2?
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What is the reaction that produces FePO4?
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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
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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.