Mining Paper 2 May/June 2015

Question 13

  1. (a)        Define extractive metallurgy.
    (b)        List two branches of extractive metallurgy.
    (c)        Explain the two branches of extractive metallurgy listed in (b) above.

Observation

This question was not very popular among the candidates and the performance of
the candidates who answered the question was poor.
Extractive metallurgy is the branch of metallurgy concerned with the production   
of metals from their ores. The branches of extractive metallurgy are pyrometallurgy, hydrometallurgy and electrometallurgy.

Pyrometallurgy

  • Involves thermal treatment
  • Thermal treatment leads to purification of ores or alloys
  • The process involves high degree of heat
  • The source of heat is either fossil fuels or electricity
  • Could involve roasting
  • Involves smelting
  • Involves refining
  • Metals that could be produced using pyrometallurgy include iron, zinc chromium, tin etc.
  • Carried out in furnaces

Hydrometallurgy

  • Involves the use of aqueous solution
  • Chemical reaction leads to dissolution of ores or alloys
  • Could involve use of other solvents apart from water
  • Metals are recovered from solutions
  • Could involve leaching
  • Involves pollution purification
  • Involves metal recovery
  • Metals that could be extracted through hydrometallurgy include copper, gold,  zinc etc

Electrometallurgy

  • Involves use of aqueous solutions
  • Could involve use of other solvents
  • The metallic solution is fed into electrolytic cell
  • Electric current is applied
  • The ionized metals are separated from other impurities
  • It includes electro-refining
  • Metals that could be separated using this method include gold, silver, zinc, aluminium, cobalt etc