Nuclear technology and mineral recovery

The particular aspect of nuclear technology most applicable to the mineral field, as has been pointed out by various authors, is nuclear blasting. The prime target for this nuclear blasting has usually been a large disseminated deposit of copper mineralization which, because of large dimensions, employs the nuclear devices most effectively. From the work of the AEC we know that the larger nuclear devices fragment rock for a lower energy cost per unit of ground broken than do smaller nuclear devices or chemical explosives. A mineralized deposit near the surface is usually not amenable to nuclear fragmentation, nor are the more deeply buried thin deposits. Also, one would not anticipate fragmenting a zone of excessively erratic mineralization with nuclear devices. Many of our mineralized areas would be eliminated using the above criteria, so at this point you are well aware that my self-imposed limitation is to nuclear blasting and large disseminated copper deposits. As with most other industries, copper mining faces rising costs and greater demands for its products. One of the rising cost features peculiar to extractive industries is the reliance placed on production from lower grade deposits as the higher grade deposits are depleted. As the grade or metal content of an orebody decreases more material must be handled to produce a given amount of metal. The increased volume of ore which must be handled as the grade declines requires expansion of facilities and higher capital expenditures. Expansion of facilities for mining, milling, and concentrating of the ore increases the per unit capital cost of the end product--copper. Increased copper consumption will aggravate this situation with demand for more metal, much of which will have to be obtained from lower grade deposits. As the higher grade deposits are depleted, future production will come from those deposits which cannot be exploited economically today. Most familiar of the proposed new methods for copper mining is in situ leaching, often mentioned in conjunct with nuclear blasting. In situ leaching has been practiced for years in underground copper mines throughout the world. Ground which has been fragmented due to subsidence over old mined-out areas and low-grade mineralization, which has remained after block caving operations, has been leached successfully. In a nuclear in situ operation we intentionally fragment the rock and then leach it to extract the values. Most of the development work for a solution collection system in old mine areas and block caved areas had been done during the original mining operations, which paid for driving these openings. In virgin ground, the cost of this development work must be borne by the in situ leaching operation. We know that in situ leaching as a method for the extraction of copper values is physically feasible. We need to know if the nuclear in situ method is economically feasible. The answers to questions of total recovery, rate of recovery, contamination, etc., must be found so that we know if we are talking of mineralized zones or orebodies