Frasch

Frasch refers to the Frasch process, a method for mining elemental sulfur, named after Rudolf Hugo Frasch. Frasch (1851–1914), a German-born American chemical engineer, developed the process in the late 19th century. The technique enabled exploitation of sulfur deposits that lay deep underground or beneath insoluble rock by melting the sulfur in place and lifting it to the surface.

The process uses drilling into sulfur beds and circulating superheated water down into the deposit, melting the sulfur in situ. A separate supply of air or gas creates pressure to lift the molten sulfur up through the well to the surface, where it is collected and cooled into solid form. The system typically employs concentric pipes: one for delivering hot water, another for lifting the melt via gas or air, and a third for returning the sulfur to surface.

Commercial adoption began in the early 20th century, with major production concentrated in the Gulf Coast region of the United States and other sulfur-bearing areas worldwide. The Frasch process was especially advantageous for deposits that were deep, covered by impermeable layers, or otherwise difficult to mine using conventional methods. However, it is energy- and water-intensive, and as mining technologies evolved, open-pit and other methods became more economical. The use of the Frasch process declined in many regions after the mid-20th century, though it remained in use in some locations where traditional mining was impractical.