### Theory:

Chemical method or Leaching:

This method is used when the ore is in a very pure form.

Leaching
• The ore is treated with a suitable reagent such that the ore is soluble in it, but the impurities are not.
• The impurities are removed by filtration.
• The solution of the ore, i.e., the filtrate, is treated with a suitable reagent that precipitates the ore.
Example:
Bauxite $$Al_2O_3.2H_2O$$, (the ore of aluminium).
The extraction of metal from metal oxide can be categorized into three types:

 More reactive metals Medium reactive metals Less reactive metals $$Na$$, $$K$$, $$Ca$$, $$Mg$$, $$Al$$ $$Zn$$, $$Fe$$, $$Pb$$, $$Cu$$ $$Ag$$, $$Hg$$ Electrolytic reduction of metal oxide into metal Chemical reduction of metal oxide into metal using coke Thermal decomposition of metal oxide into metal

Occurrence of ores in Tamil Nadu:

The following minerals can be found in the state of Tamil Nadu.

Lime stone:
• Coimbatore, Cuddalore, Dindugul
Gypsum:
• Tiruchi and Coimbatore Districts
Titanium minerals:
• Kanyakumari, Tirunelveli and Tuticorin.
Chromite:
• Coimbatore and Salem district.
Magnetite:
• Dharmapuri, Erode, Salem, Thiruvannamalai.
Tungsten: