Chapter 19:Extraction of Metals

Extraction of metals

• The Earth’s crust contains metals and metal compound
  • [ ] such as gold, copper, iron oxide and aluminium oxide
• A metal ore is a rock that contains enough of the metal to make it worthwhile extracting
• They have to be extracted from their ores through processes
  • [ ] such as electrolysis, using a blast furnace or by reacting with more reactive material
• Obtaining from ores is a reduction process
• Middle order metals like iron are extracted by reducing with carbon in the blast furnace.
  • [ ] Blast furnace uses three raw materials (coke ,limestone and iron) .
  • [ ] Coke burns to produce carbon monoxide and heat producing Pig Iron-
• Iron ore+ carbon monoxide ➡️iron + carbon dioxide
• Limestone ➡️lime + carbon dioxide
• Lime + sand ➡️calcium silicate
• Aluminium ore is called bauxite .
  • [ ] The bauxite is purified to produce aluminium oxide.
  • [ ] The extraction is done by electrolysis.
  • [ ] The ions in the aluminium oxide must be free to move so that electricity can pass through it

Rusting

• Reaction of iron with air /oxygen and water to form rust.
• Rusting is a redox process.
• You can prevent it by panting or coating with oil or grease, metal or electroplating.