Mining The Ocean With “Dry-Land” Technique

Press, Volume CX, Issue 32361, 29 July 1970, Page 11

Mining The Ocean With “Dry-Land” Technique

(Bp MONTY HOYT, in the "Christian Science Monitor")

“Ocean mining in the future will employ the Red Sea approach. The waters will be pushed back and men go down in a shirt-sleeve atmosphere to mine the valuable minerals of the Continental Shelf,” predicts Mr J. Leslie Goodier, former chief of Marine Mining Systems Development for the United States Bureau of Mines.

Dangling strings, dropping buckets, or sending men to the sea floor in diving suits is hardly suitable mining procedure, says Mr Goodier, who now serves as oceans engineer with Arthur D. Little, Inc., in Cambridge, Mass. "We will have to aim at developing the same environment as on land” if offshore mining is to be economically feasible. The development of a bubble atmosphere, or habitat on the sea bottom, may not be more than a decade or so away, he projects. Demand for minerals and land mining costs will determine how soon. “AU you need Is one successful mine offshore to have everyone jumping in the ocean," Mr Goodier claims. Unlike gas and oil,which have been drilled on the Continental Shelf for the last 30 years, hard minerals have only recently become the object of mining efforts. Offshore Minerals Out of $1 billion world offshore mineral production in 1967, three-fourths came from coal recovered through tunnels from shore and chemicals taken from water. Eliminate sand, gravel, oyster shells, and sulphur from the remaining total, and there remains a sum of $5O million—the annual value of tin, iron, heavy minerals, and diamond production taken from the sea floor. While ocean mining figures are small, world demand for many minerals is expected to double by 1986 and triple by the end of the century. Coal has been mined from onshore shafts or artificial reefs off the coasts of the United Kingdom, Canada, Japan, and Taiwan for some time. Iron ore has been mined off Newfoundland and Finland; tin off Indonesia. Similar onshore deposits along the coastline of Alaska, California, and New England suggest these formations project out on to the shelf. “Most people have a mental block that mineral resources come to the water’s edge and stop,” Mr Goodier says, “but the geology doesn’t end there.” Problems Faced Four factors militate against mining offshore re-

sources in the United States in the near future: Little exploration has been undertaken to determine the location and extent of offshore hard mineral deposits. The Stratton Commission report "Our Nation and the Sea” prepared for the President call for a "decade of o-ean exploration” in the '7o’s. The report states, however, that "the value of these (offshore mineral) resources is at this time entirely speculative because of the lack of any systematic knowledge of their location or composition.” It is paradoxical that a large proportion of available sea floor pictures of the deep ocean off United States coasts come from Soviet sources. Russian hydrographic “fishing” trawlers have travelled up and down the Atlantic Coast in legitimate areas of investigation sounding and profiling the ocean bottom, taking great numbers of oceanographic pictures. Incentives for private companies to explore offshore areas are minimal. Present federal law (now under revision) and many coastal state laws do not quarantee an original exploring agent a mining licence once a prospective site has been discovered. The land is first advertised for sale and then opened to competitive bidding. Risk Higher Alaska is an exception. Exploratory permits in state waters can be converted into mining licences. The state further encourages exploration by waiving all royalties, content with revenues from leasing the land. A higher risk and cost exists for off-shore mining than land operations.

Modern technology has not solved all the problems of off-shore mining.

Dredging Improved

Mr Goodier, who participated in the United States Navy Sealab 2 project (an underwater habitat), says none of the undersea mines, bottom crawlers, and deepdiving submersibles has a proven capability for recovery of minerals evep from shallow depths of 200 feet. The dredging industry, however, has developed this capacity, he states. One of the most successful models is an air lift dredge. A cutting shaft can mine compacted sand and bedrock from the ocean floor, while a mobile suction head vacuums the material into a waiting barge.

Further studies are necessary for de-watering systems capable of retaining solids and discbarging water overboard, according to Mr Goodier. Present de-watering plants are too large to be manageable.

It is estimated that ocean mining even in shallow waters is more than double the cost of equivalent landbased operations. The ratio of exploration costs' to potential profit, the Stratton report relates, is much larger with most hard minerals than with oil. Ashore, the ratio of targets explored to deposits recovered is 1000 to 1; it is generally conceded the ratio is higher in the off-shore environment