465 



SEA WATER AND ITS MINERALS 



The most abundant and most essential of world resources is the water 

 of the ocean. The accelerating increase in human population, and the 

 soaring demands for industrial and agricultural use of fresh water, 

 have created acute water shortages around the world. The worsening 

 pollution of the fresh-water supply and the demands of arid areas 

 where normal water supplies are nonexistent highlight the need for 

 turning to sea water. 



Desalination — the production of potable water from sea water — 

 is now an active concern, and many countries suffering from water 

 shortages are erecting and utilizing desalting plants for their 

 domestic needs. More than 600 desalting plants of 25,000 gallons 

 per day capacity or greater are in operation or under construction in 

 the world. Their total production of potable water exceeds 200 million 

 gallons per day. It is estimated that by 1975 worldwide utilization 

 of desalting plants will result in the production of 1 billion gallons 

 of fresh water per day. 38 



The sea holds about 330 million cubic miles of water, which contain 

 an average of Sy 2 percent of various elements in solution. Each cubic 

 mile weighs some 4.7 billion tons and holds about 166 million tons 

 of solids. 39 The most abundant of these is common salt — sodium chlo- 

 ride. Its two main elements, sodium and chlorine, constitute more than 

 85 per cent of all the solids dissolved in sea water. Salt has been ex- 

 tracted from sea water since time immemorial and, although some of 

 the machines and tools used today are modern, the basic techniques 

 of salt mining by solar evaporation is still prevalent around the world. 



Besides common salt, sea water contains commercially extractable 

 amounts of magnesium metal and compounds, and smaller amounts of 

 bromine, iodine, calcium, and potassium compounds. There are at pres- 

 ent some 300 near-shore operations in 60 countries engaged in the 

 production of these minerals. 40 Quantitative chemical analyses reveal 

 the presence in sea water of all but about a dozen of the stable ele- 

 ments; advanced analytical techniques may eventually reveal the pres- 

 ence of virtually all known elements in sea water. 



One of the latest milestones in mineral extraction from sea water 

 was the invention of a process for extracting uranium oxide. Developed 

 by N. J. Keen at Britain's Atomic Energy Research Establishment at 

 Harwell, the process promises a final product at $20 per pound. 



Of the more appealing constituents of sea water, precious metals 

 have been the object of unrewarding research and experimentation for 

 some time. Silver is the most abundant precious metal in sea water, but 

 most attempts have concentrated on the extraction of gold. 41 



38 Milton S. Sachs. "Desalting Plants. Inventorv Report No. 1." Report of Office of 

 Saline Water, U.S. Department of the Interior. (Washington, U.S. Government Printing 

 Office, January 1, 1968.) 



30 Mero., op. cit., page 4. 



40 Frank Wane. "Mineral Resources of the Sea." (U.N. Department of Economic and 

 Social Affairs. ST/EPA /125. April 1970. page 4.) This is an updated version of an identi- 

 cal report of the Secretary-General dated February 19, 1968. 



41 Numerous gold extraction processes have be^n patented, but none has yet been found 

 that could be classified as economical. Gold concentration in sea water has been found to 

 vary from 0.001 milligrams per ton to almost 60 mg/ton, with an average about 0.04 mg/ 

 ton. Of all these attempts, only one case is known where anv measurable amount of gold 

 was actuallv obtained. This was done by the Dow Company in their bromine extraction 

 facilitv in North Carolina. Fifteen tons of sea water were processed, producing 0.09 milli- 

 grams of gold, worth about $0.0001. [See John L. Mero. op. cit, page 42.] 



