Question

Which of the following is extracted through underground mining?

• A. Tin
• B. Gold
• C. Iron ore
• D. Sulphur

Answer 1

Answer: (D)

Sulphur

• The Frasch process is a method to extract sulfur from underground deposits.
  
• It is the only economic method of recovering sulfur from elemental deposits.
  
• In the Frasch process, superheated water is pumped into the sulfur deposit; the sulfur melts and is extracted.
  
• The Frasch process is able to produce high purity sulfur.
  
• In the Frasch process, three concentric tubes are introduced into the sulfur deposit. Superheated water (443k,165 °C, 2.5-3 MPa) is injected into the deposit via the outermost tube. Sulfur (m.p. 115 °C) melts and flows into the middle tube.
  
• Water pressure alone is unable to force the sulfur into the surface due to the molten sulfur's greater density, so hot air is introduced via the innermost tube to froth the sulfur, making it less dense, and pushing it to the surface.
  
• The sulfur obtained can be very pure (99.7 - 99.8%).
  
• In this form, it is light yellow in color