MINING OF SULPHUR

               MINING OF SULFUR  (FRASH PROCESS)

PROPERTIES OF SULFUR:

• Symbol: S
• Atomic Number: 16
• Atomic Weight: 32.06
• Classification: Nonmetal
• Phase at Room Temperature: Solid
• Density: (alpha) 2.07 grams per cm cubed
• Melting Point: 115.21°C, 239.38°F
• Boiling Point: 444.6°C, 832.3°F

  FRASH PROCESS:

Superheated water at 170°C and hot compressed air are forced 

underground through pipes, forcing water and molten sulphur to the 

surface. Sulphur is insoluble in water and so the two substances emerging 

from the pipes are easily separated. The sulphur is kept molten and sold in 

this form. The sulphur obtained from this process is about 99.5% pure.

- Most sulphur is extracted from mineral deposits using the Frasch process. 

Superheated stream is pumped down the outer of 3 concentric pipes into the 

sulphur deposit, and since sulphur has a low melting point (119) it is readily 

melted. At the same time, compressed air is blown down the inner pipe, and 

because sulphur has a relatively low density, the air is able to force the molten 

sulphur up the middle pipe to the surface where it resolidifies. The insolubility of 

sulphur in water means that it separates from any water, leaving 99.5% pure 

sulphur.

- Sulfur is also obtained from hydrogen sulphide in natural gas and petroleum. 

Incomplete combustion of H2S in a furnace produces SO2 and S. 

3H2S(g) + O2(g)  H2S(g) + 3S(g) + SO2(g)

The mixture is cooled to condense the sulphur.

- Sulfur is also released as sulphur dioxide when metal sulphide ores are smelted.

Eg. ZnS(s) + O2(g)  Zn(s) + SO2(g)

Environmental Issues:

- Sulfur is easily oxidised to sulphur dioxide or reduced to hydrogen sulfide, both 

of which are serious air pollutants at quite low concentrations. Care is needed to 

ensure that there is no inadvertent oxidation or reduction of sulphur

- It is very difficult to back-fill the underground caverns left by extraction of SULFUR

A 'striking surface' is made of sand, powdered glass and a chemical called 'red phosphorus'. The head of matchstick is made of sulfur, glass powder .