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Describe extraction of Sulphur by Frasch process | web4study
Describe extraction of Sulphur by Frasch process
EXTRACTION OF SULPHUR (FRASCH PROCESS):
Most of the world’s sulphur is obtained from underground, deposits which may be more than 200 metres below the surface of the earth. About 60- 70% native sulphur occur deep below the earth’s surface. For this reason, sulphur cannot be dug out directly by ordinary mining. For the extraction of sulphur an ingenious method was discovered by Herman Frasch, an American en inner, known a!’l Frasch Process.
In this process, a hole about 30cm in diameter is drilled through the soil layers to the sulphur bed. Three concentric iron pipes are sunk into the bore or hole. The outer most pipe. (20 cm diameter) is sunk up to the deposits and the next inner pipe (10 cm diameter) is held a little above the surface of the sulphur deposits. Superheated water at about 170°C and 100 atmospheric pressure are forced through the outermost pipe to the sulphur bed to melt sulphur (m.p = 115°C) of the sulphur bed. Hot compressed air at a pressure of 15 atm is then flown down the innermost pipe 5cm diameter to force the molten sulphur up through the middle tube or pipe.
This sulphur is prevented from solidifying by the high temperature of the middle pipe whose temperature is maintained by the heat of the super-heated water in the outer side and also hot compressed air on the inner 1 side.
The molten sulphur is continuously pumped into a receptacle at the surface where it is allowed to solidify in large wooden tanks. The sulphur obtained is bout 99.5% pure.