Metallurgy

Synopsis

• Comparison of Metals and Non-Metals
  Physical Properties of Metals and Non-Metals
  
  

Chemical Properties of Metals and Non-Metals:

     Occurrence of Metals

• The Earth’s crust is the major source of metals.
• Most of the metals are reactive and hence they do not occur as free elements in nature.
• Less reactive elements such as copper, silver, gold and platinum occur in a free state as metals.
• Copper and silver metals also occur in the combined state in the form of compounds.

• Mineral & Ores
  Minerals: The naturally occurring compounds of metals, along with other impurities are known as minerals.
  Ores: The minerals from which metals are extracted profitably and conveniently are called ores.
  Gangue: Earthly impurities including silica, mud, etc. associated with the ore are called   gangue.
  Metallurgy: The process used for the extraction of metals in their pure form from their ores is referred to as metallurgy.

•  Extraction of Metals

• The reactivity of elements differs for different metals.
• Metals at the top of the reactivity series (K, Na, Ca, Mg, Al, etc.) are reactive and they are never found in nature as free elements.
• Metals in the middle of the reactivity series (Zn, Cu, Pb, etc.) are moderately reactive.
• Metals at the bottom of the series (Au, Ag, Pt, etc.) are the least reactive and occur in a free state.
  
   

• Three major steps involved in the extraction of metals from its ore are
  
  

• Enrichment of Ores

• The ores of metal are usually contaminated with a large amount of impurities such as sand, soil, etc. called gangue.
• Before extracting the metal from an ore, it is necessary to remove these impurities.
• The method used for removing gangue from the ore depends on the differences between the physical and chemical properties of the gangue and the ore.

• Conversion of Concentrated ore into Metal

• The extraction of a metal from its concentrated ore is essentially a process of reduction of the metal compound present in the ore.
• The method of reduction to be used depends on the reactivity of the metal to be extracted.