Electrorefining of Copper and Metal Properties
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Questions and Answers

Which of the following impurities found in the 'tough pitch' copper are NOT dissolved into the solution during the electrolytic refining process?

  • Silver (correct)
  • Zinc
  • Nickel
  • Iron

    • What is the primary function of the graphite coating on the cathodes used in the electrolytic refining of copper?

  • To protect the cathode material from corrosion
  • To prevent the copper from adhering to the cathode (correct)
  • To act as a catalyst for the electrodeposition process
  • To increase electrical conductivity

    • What is the primary reason why the anode mud or slime is considered valuable in the electrolytic refining of copper?

  • It contains a high concentration of copper that can be recovered
  • It is a valuable source of sulfur for further industrial processes
  • It can be used as fertilizer due to its high nutrient content
  • It contains precious metals like silver and gold that can be recovered (correct)

    • Which of the following mechanical properties of metals is defined as the ability to resist permanent deformation under stress?

    <p>Hardness (D)</p> Signup and view all the answers

    Which of the following materials is NOT mentioned in the text as an example of a metal with high hardness?

    <p>Sodium (D)</p> Signup and view all the answers

    In the context of smelting, what is the primary function of coke?

    <p>To act as a reducing agent, converting the metal oxide into metal (A)</p> Signup and view all the answers

    Why is carbon a suitable reducing agent in the carbon reduction process?

    <p>All of the above (D)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the calcination process?

    <p>The process is carried out in a blast furnace (D)</p> Signup and view all the answers

    What role does lime play in the smelting process?

    <p>Lime reacts with impurities in the ore to form slag, which is then removed (A)</p> Signup and view all the answers

    In the alumino-thermic process (thermite), what is the role of the aluminum powder?

    <p>Aluminum powder acts as a reducing agent, converting the iron oxide into iron (B)</p> Signup and view all the answers

    What is the chemical formula for the slag formed when lime reacts with silica?

    <p>CaSiO<sub>3</sub> (D)</p> Signup and view all the answers

    Which of the following metals can be extracted using the carbon reduction process?

    <p>Iron (B)</p> Signup and view all the answers

    What is the primary function of the twyers in a blast furnace?

    <p>Twyers are used to inject hot dry air into the furnace, providing oxygen for the combustion process (A)</p> Signup and view all the answers

    What is the chemical equation for the reaction between iron oxide and carbon in a blast furnace?

    <p>Fe<sub>2</sub>O<sub>3</sub> + 2C → 2Fe + 3CO (B)</p> Signup and view all the answers

    Which of the following elements is NOT a good example of a highly ductile metal?

    <p>Iron (A)</p> Signup and view all the answers

    What is the primary purpose of using flux in the blast furnace during the reduction of haematite?

    <p>To remove impurities by forming slag. (D)</p> Signup and view all the answers

    Which of the following properties does NOT describe malleability?

    <p>The ability to be drawn into wires. (A)</p> Signup and view all the answers

    What is the chemical formula for the slag formed when lime reacts with silica in a blast furnace?

    <p>CaSiO<sub>3</sub> (A)</p> Signup and view all the answers

    In the poling process, what is the role of the green logs of wood?

    <p>To introduce hydrocarbons that reduce metal oxide impurities. (A)</p> Signup and view all the answers

    Which of the following is NOT a common impurity removed during the poling process?

    <p>Copper (C)</p> Signup and view all the answers

    What is the primary function of a perforated ladle in the poling process?

    <p>To remove the oxidized impurities that form a scum on the surface. (C)</p> Signup and view all the answers

    What is the primary purpose of roasting in metallurgy?

    <p>To convert the ore into a form suitable for reduction. (A)</p> Signup and view all the answers

    Which type of ore is specifically treated by roasting?

    <p>Sulphide ores (B)</p> Signup and view all the answers

    What is the main product of roasting zinc sulfide (ZnS)?

    <p>Zinc oxide (ZnO) (B)</p> Signup and view all the answers

    What is the primary difference between brass and bronze?

    <p>Brass contains zinc, while bronze contains tin. (C)</p> Signup and view all the answers

    What is the typical range of zinc content in brass?

    <p>40% to 60% (D)</p> Signup and view all the answers

    Which of the following properties is NOT characteristic of brass?

    <p>High electrical conductivity (D)</p> Signup and view all the answers

    What is the primary use of Dutch metal or low brass?

    <p>Jewellery and musical instruments (B)</p> Signup and view all the answers

    What is the key characteristic of a metal that makes it suitable for use in electrical transmission cables?

    <p>High electrical conductivity (A)</p> Signup and view all the answers

    What is the purpose of adding other metals like tin, manganese, aluminum, or iron to brass?

    <p>To improve the mechanical properties of the alloy. (A)</p> Signup and view all the answers

    Study Notes

    Electrorefining of Copper

    • Tough pitch copper (99.2-99.6% Cu) can be refined to 99.98% purity using electrolysis.
    • Anodes are thick plates of tough pitch copper.
    • Cathodes are thin plates of pure copper coated with graphite.
    • Refining tank is a wooden vat lined with lead sheets.
    • Electrolyte is 15% CuSO₄ solution and 5-10% sulphuric acid.
    • Copper ions are discharged at the cathode, forming pure copper.
    • Sulphate ions react with copper at the anode, forming copper sulphate.
    • Impurities like Zn, Fe, Ni, Se, Te, and Pb go into solution as sulphates and don't deposit on the cathode.
    • Gold and silver create insoluble deposits (anode mud/slime).
    • Precious metals (Ag, Au, Pt) are recovered from the anode mud.

    Mechanical Properties of Metals

    • Metals have various physical and mechanical properties important in engineering.
    • Hardness is the resistance to wear, penetration, and scratching. Sodium and potassium are soft, while iron and tungsten are hard.
    • Ductility is the ability to be stretched into wires without breaking. Gold, silver, and platinum are highly ductile.
    • Malleability is the ability to be hammered into shapes without cracking or rolled to thin sheets. Gold, silver, platinum, aluminium, and copper are malleable.
    • Toughness is a combination of strength and elasticity.
    • Brittleness is the tendency to break easily.
    • Tensile strength is the maximum stress a material can withstand before breaking.
    • Weldability is the ability of a material to fuse together.
    • Machinability is the ease with which a material can be shaped.
    • Tenacity refers to strength and persistence.

    Other Refining Methods

    • Poling: Uses wood to oxidize impurities, making the metal purer.
    • Aluminothermic: Uses a mixture of aluminium and metal oxide (thermite) to reduce the metal oxide. Magnesium wire involved.
    • Carbon reduction: Used for metals with high atomic weights, involves high temps. Oxides are converted to metal using a reducing agent (e.g., carbon), typically in blast furnaces, mixing ore, coke, and flux (like limestone).

    Chemical Processes

    • Calcination: Heating ore in limited air, removes moisture and decomposes some compounds.
    • Roasting: Heating ore in air, mainly for sulphide ores to form oxides.
    • Reduction: A process of converting metal oxides into the free metal (usually using carbon or another reducing agent). Done in blast furnaces, reverberatory furnaces, or other heating systems.

    Various Steels and Alloys

    • Different types of steel and alloys have various properties and uses.
    • Mild steel is soft, tough, easy to weld, and used for wires and sheets.
    • Medium carbon steel is harder than mild steel, heat-treatable, and used for various structures.
    • High carbon steel is hard, tough, and resistant to wear, with a keen cutting edge.
    • Brass is an alloy of copper and zinc, used for many applications. The composition greatly determines the strengths and weaknesses.
    • Bronze is an alloy of copper and tin, with specific strength and corrosion resistance.
    • Solders are alloys used for joining metals.
    • Duralumin is an alloy of aluminum, copper, magnesium, and manganese, it's corrosion-resistant, strong, and lightweight.
    • Wood's Metal is a low-melting fusible alloy, used in safety devices and other applications.

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    Applied Science PDF - Mechanical Properties of Metals

    Description

    This quiz covers the processes of electrorefining copper, including the role of anodes, cathodes, and electrolytes. Additionally, it explores the mechanical properties of metals, such as hardness and ductility, which are essential in engineering applications.

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