Offshore sulphur mineIn 1960, the first U.S. offshore sulphur mine began extracting sulphur. The Grand Isle offshore mine was built and operated by the Freeport Sulphur company, about 7 miles off the Louisiana coast in the Gulf of Mexico. A steel structure with drilling rigs stood in 50-ft of water to reach the deposit 2,000-ft below the ocean bed. The rig also carries generators and boilers to generate the superheated water injected into the bore in the Frasch extraction process to melt the sulphur and help drive the molten material to the surface. Humble Oil & Refining Co. discovered sulphur-bearing limestone while test drilling for oil in 1949, and within five years had eight more sulphur prospect holes. Freeport Sulphur Co. acquired the mineral rights on 19 Sep 1956. More than $22 million was spent on pre-production construction.« |
