FRASCH PROCESS.

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• Sulphur occurs about 200M underground .A strata of loose clay and sand above the sulphur deposits make ordinary mining impossible.A special method of mining called the Frasch process is therefore employed.

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• The process is based on the low melting point of sulphur which ranges from 113 degrees Celsius to 119 degrees Celsius.
• In this process,three concentric pipes of different diameters 2 cm, 8cm and 15 cm are sunk into the sulphur deposits underground as shown in the next slide.

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• Water is heated to about 170 degrees Celcius under pressure of 10 atmospheres and is forced down the outermost pipe.
• The pressure ensures that the water remains in liquid state at such high temperature.

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• Hot air at a pressure of 15 atmospheres is forced down the innermost pipe.
• This produces a light froth consisting of a mixture of molten sulphur and water.The high pressure forces the mixture up the middle pipe.
• The mixture is run into large tanks on the surface where the sulphur solidifies at 115 degrees Celsius, Separates from the water and is stored.
• Sulphur obtained in this way is usually over 99% pure.