Frasch Process
Definition and meaning of Frasch Process in chemistry.
Frasch process is an industrial method for extracting elemental sulfur from underground deposits by melting it in place with superheated water and pushing the liquid sulfur to the surface with compressed air.
In more detail
Developed by Herman Frasch in the 1890s, the process uses three concentric pipes sunk into a sulfur-bearing deposit. Superheated water (around 160-170°C, kept liquid under pressure) is pumped down the outer pipe to melt the sulfur, which has a melting point of only about 115°C. Compressed air forced down the central pipe then whips the molten sulfur into a low-density froth that rises through the middle pipe to the surface. Because the sulfur melts and rises with little contact with rock, the recovered product is typically 99.5-99.9% pure, needing no further refining.
Key facts
| Field | Inorganic Chemistry |
|---|---|
| Developed by | Herman Frasch, 1891 |
| Key materials | Superheated water (~160-170°C) and compressed air |
| Product purity | ~99.5-99.9% elemental sulfur (S8) |
The Frasch process was used extensively to mine sulfur from salt-dome deposits along the Gulf Coast of Texas and Louisiana throughout much of the 20th century.
Frequently asked questions
Why is compressed air needed in the Frasch process?
Compressed air pumped down the innermost pipe aerates the molten sulfur, creating a frothy sulfur-water-air mixture that is buoyant enough to rise through the extraction pipe to the surface.
Is the Frasch process still used today?
Rarely. It has largely been displaced by recovering sulfur as a byproduct of removing hydrogen sulfide from natural gas and petroleum via the Claus process, which is cheaper and produces most of the world's sulfur today.