A-Blast for Copper

Under its Plowshare program, the Atomic Energy Commission has been investigating the use of nuclear explosives to blast out harbors and canals, to create underground storage cavities, and to release natural gas and oil locked beneath the surface of the earth. Now, in an attempt to do something about growing shortages of copper in the U.S., a team of scientists has worked out a nuclear plan to mine billions of tons of copper-bearing ore too poor to be mined by traditional methods.

Scientists from the AEC, the U.S. Bureau of Mines, the University of California's Lawrence Radiation Laboratory and the Kennecott Copper Corp. have proposed a test (named Project Sloop* by the AEC) near Safford, Ariz. There, under a layer of volcanic rock more than 500 ft. thick, Kennecott test drillings have revealed a 2-billion-ton reserve of ore containing about 4/10 of 1% of copper.

If Congress and the AEC approve, scientists will drill a 20-in. shaft 1,200 ft. down into the ore deposit. They will then lower a 20-kiloton device to the bottom, plug the shaft, and set off a nuclear blast. From experience with previous tests, the AEC knows that the explosion will create tremendous pressures that will literally push the rock away from the blast center, fracturing it in all directions. The result will be a cavity about 200 ft. in diameter; the surface of the earth will quake, but the AEC does not expect any radioactive debris to be vented into the atmosphere. Rock, melted by the explosion and lining the interior of the cavity, will flow down the walls, forming a pool at the bottom that will solidify into a glassy mass containing as much as 90% of the radioactive products of the A-blast. At the same time the roof of the cavern will begin to collapse, eventually forming a 440-ft. cavity filled with fractured copper ore.

After about eight months--enough time for radioactivity to decrease to safe levels--mining engineers will drill three holes from the surface to the top of the "chimney" of fractured rock. Through these holes, sulfuric acid will be poured into the chimney, where it will dissolve copper out of the rock. The solution, containing copper sulfate, will then drain into holes drilled at the bottom of the chimney and be pumped up through a shaft to a precipitation plant at the surface. There the solution will be processed to extract metallic copper, and the recovered sulfuric acid recycled for another trip through the chimney.

Project Sloop will cost an estimated $13 million, and could take 30 months from authorization through evaluation. If it works, technicians using nuclear devices as powerful as 100 kilotons may some day be able to process tens of millions of tons of ore containing copper that is now beyond man's grasp.

*Names of Plowshare projects are not acronyms but tend to have something to do with transportation. Examples: Cabriolet (for excavation), Gasbuggy (for releasing natural gas), Ketch (for underground gas storage).

This file is automatically generated by a robot program, so reader's discretion is required.