Isolation of Metals - Extraction of metal from ore and its part

  • Definition of metallurgy
  • Importance of extraction of metals
  • Types of ores
  • Steps involved in the extraction of metals
  • Concentration of ore
  • Beneficiation process
  • Reduction of ore
  • Purification of metal
  • Electrolytic refining
  • Refining by distillation

Definition of Metallurgy

  • Metallurgy is the process of extraction of metals from their ores and preparation for use in various applications. Examples:
  • Extracting iron from iron ore
  • Extracting copper from copper ore
  • Extracting gold from gold ore

Importance of Extraction of Metals

  • Metals are essential for various industries, construction, and everyday objects.
  • Extraction of metals allows us to obtain pure and usable forms of these metals.
  • Industries rely on the availability of metals for manufacturing and production. Examples:
  • Iron for building structures
  • Aluminum for making aircraft
  • Gold for jewelry

Types of Ores

  • Ores are naturally occurring rocks that contain metal or metal compounds in sufficient amounts to make the extraction economically viable. Types of ores:
  1. Oxide ores (e.g., hematite, magnetite)
  1. Sulfide ores (e.g., pyrite, galena)
  1. Carbonate ores (e.g., limestone, dolomite) Examples:
  • Hematite ore for extracting iron
  • Galena ore for extracting lead

Steps Involved in Extraction of Metals

  1. Concentration of ore
  1. Beneficiation process
  1. Reduction of ore
  1. Purification of metal
  1. Refining by distillation or electrolytic refining Examples:
  • Concentration of bauxite ore for extracting aluminum
  • Reduction of iron ore using carbon monoxide

Concentration of Ore

  • The process of removal of impurities from ore to increase the metal content is called concentration of ore. Methods of concentration:
  • Gravity separation
  • Froth flotation
  • Magnetic separation Equation:
  • Example of concentration of copper ore using froth flotation:
    • Cu2S (copper sulfide) + 2H2O (water) + 3O2 (oxygen) → 2CuO (copper oxide) + 2H2SO4 (sulfuric acid)

Beneficiation Process

  • The beneficiation process involves the reduction of ore particles size and increasing the surface area for better reaction during extraction. Methods of beneficiation:
  • Crushing
  • Grinding
  • Screening Examples:
  • Crushing bauxite ore into smaller particles
  • Grinding iron ore into fine powder

Reduction of Ore

  • The process of converting an oxide ore into metal by using a reducing agent is called reduction of ore. Methods of reduction:
  • Smelting
  • Carbon reduction
  • Self-reduction Examples:
  • Reduction of alumina (Al2O3) to obtain aluminum metal
  • Reduction of iron ore (Fe2O3) using carbon monoxide (CO)

Purification of Metal

  • The purification process involves the removal of impurities from the extracted metal. Methods of purification:
  • Liquation
  • Distillation
  • Electrolytic refining Examples:
  • Purification of silver by liquation
  • Purification of copper by electrolytic refining

Electrolytic Refining

  • Electrolytic refining is a process used to obtain pure metals by the electrolysis of impure metal. Process:
  1. Impure metal is made the anode, and a pure metal sheet is made the cathode.
  1. Electrolyte is a solution of the salt of the metal being refined.
  1. When electric current is passed, impure metal dissolves in the electrolyte and deposits on the cathode as pure metal. Examples:
  • Electrolytic refining of copper
  • Electrolytic refining of gold

Refining by Distillation

  • Refining by distillation is a method used for volatile metals to obtain pure metal from its impure form. Process:
  1. Impure metal is heated to obtain its vapor.
  1. The vapor is collected and condensed to obtain pure metal. Examples:
  • Refining of mercury by distillation
  • Refining of zinc by distillation Sorry, but I can’t generate slides in markdown format. Sure! Here are slides 21 to 30 in markdown format for the topic “Isolation of Metals - Extraction of metal from ore and its part”:

Refining by Distillation

  • Refining by distillation is a method used for volatile metals to obtain pure metal from its impure form.
  • It is based on the principle of differences in boiling points of the metal and impurities. Process:
  • Impure metal is heated to obtain its vapor.
  • The vapor is collected and condensed to obtain pure metal. Examples:
  • Refining of mercury by distillation
  • Refining of zinc by distillation

Refining of Mercury by Distillation

  • Mercury is a volatile metal that can be distilled to obtain pure mercury. Process:
  1. Impure mercury is heated in a distillation apparatus.
  1. Mercury vaporizes at a relatively low temperature (357 °C) and rises up the apparatus.
  1. The vapor is then condensed by passing through a cooling system.
  1. The condensed mercury is collected in a separate container as pure metal. Equation:
  • Hg(l) → Hg(g)
  • Hg(g) → Hg(l)

Refining of Zinc by Distillation

  • Zinc can also be refined by distillation. Process:
  1. Impure zinc is heated in a distillation apparatus.
  1. Zinc has a lower boiling point than most impurities, allowing it to vaporize before other metals.
  1. The zinc vapor is collected and condensed, producing pure zinc metal. Equation:
  • Zn(l) → Zn(g)
  • Zn(g) → Zn(l) Examples:
  • Refining of zinc from its ores, such as zinc blende (ZnS).

Application of Isolation of Metals - Iron Smelting

  • Isolation of metals plays a crucial role in various industries, including iron smelting. Process:
  1. Iron ore (hematite or magnetite) is first converted into iron oxide (Fe2O3) through beneficiation and reduction processes.
  1. The iron oxide is then smelted in a blast furnace, along with limestone and coke.
  1. The intense heat in the furnace melts the iron oxide, which is reduced to metallic iron.
  1. The impurities in the iron ore combine with limestone to form slag, which is removed. Equation:
  • 2Fe2O3 + 3C → 4Fe + 3CO2
  • CaCO3 → CaO + CO2

Application of Isolation of Metals - Aluminum Extraction

  • Isolation of metals is also crucial for the extraction of aluminum from aluminum ore (bauxite). Process:
  1. Bauxite ore is concentrated and converted into alumina (Al2O3) through various processes.
  1. Alumina is then mixed with molten cryolite and subjected to electrolysis.
  1. Electrolysis results in the deposition of pure aluminum metal at the cathode.
  1. The impurities settle as a molten layer at the bottom of the electrolytic cell. Equation:
  • 2Al2O3 + 3C → 4Al + 3CO2
  • Al2O3 → 2Al3+ + 3O2-

Application of Isolation of Metals - Copper Electrorefining

  • Isolation of metals is essential for obtaining pure copper for various applications. Process:
  1. Impure copper anodes and thin pure copper sheets serve as the cathodes.
  1. Copper sulfate solution (CuSO4) is used as the electrolyte.
  1. During electrolysis, copper ions from the anode are reduced at the cathode, resulting in the deposition of pure copper.
  1. Impurities settle at the bottom as anode mud. Equation:
  • Cu2+ + 2e- → Cu(s)

Application of Isolation of Metals - Gold Refining

  • Isolation of metals is necessary for refining gold and obtaining pure gold. Process:
  1. Impure gold is dissolved in aqua regia (a mixture of concentrated nitric acid and hydrochloric acid).
  1. The gold chloride complex formed is reduced to metallic gold using reducing agents like sulfur dioxide or oxalic acid.
  1. The reduced gold is then precipitated and further purified. Equation:
  • AuCl4- + 3SO2 + H2O → Au + 4Cl- + 3H2SO4

Environmental Impact of Metal Extraction

  • Metal extraction processes can have negative environmental impacts if not managed properly. Environmental concerns:
  1. Mining activities can lead to deforestation, disruption of ecosystems, and habitat destruction.
  1. Smelting and refining processes can release harmful pollutants, including sulfur dioxide and heavy metals, into the air and water.
  1. Improper disposal of waste materials, such as tailings, can contaminate soil and water bodies.

Advancements in Metal Extraction Techniques

  • Over time, advancements in technology have led to more efficient and environmentally friendly metal extraction techniques. Advancements:
  1. Use of renewable energy sources for power in smelting and refining processes.
  1. Adoption of closed-loop systems to minimize waste generation and improve resource efficiency.
  1. Development of more efficient and selective extraction methods to reduce the environmental impact.
  1. Integration of recycling and circular economy principles to reduce reliance on primary metal sources.

Summary

  • Metallurgy is the process of extracting metals from their ores.
  • Steps involved in the extraction of metals include concentration, beneficiation, reduction, purification, and refining.
  • Different methods like electrolytic refining and distillation are used for purification and refining.
  • Metal extraction has various applications, such as iron smelting, aluminum extraction, and gold refining.
  • Environmental concerns and advancements in extraction techniques are important considerations.