The San Francisco Operations Office of the United States Atomic Energy Commission, the Lawrence Radiation Laboratory, the United States Bureau of Mines, and the Kennecott Copper Corporation, with the technical assistance of the Oak Ridge National Laboratory, have cooperatively investigated the feasibility of fracturing low-grade copper deposits with nuclear explosives in preparation for extracting copper by in-place (in-situ) leaching methods.

The study was conducted as part of the U.S. Atomic Energy Commission's Plowshare Program. It includes detailed investigations of both the explosive fracturing and the leaching aspects, and includes the design of an experiment (Project Sloop) to field test the application.

If successful, the utilization of nuclear explosives for this application would:

1. Allow recovery of copper by in-situ leaching methods and eliminate the necessity of mining and bringing to the surface huge quantities of material for recovery treatment.

2. Increase the Nation's available domestic copper supply by allowing the economic development of vast resources of low-grade copper deposits now beyond the scope of conventional mining processes.

3. Permit large scale mining operations on a number of deep low-grade deposits with a minimum disturbance of the natural landscape.

A low-grade copper deposit near Safford, Arizona, was investigated as a possible site to test the concepts. Under the most advanced conventional mining and treatment methods, the copper in this deposit cannot currently be recovered at an attractive profit. Nevertheless, the deposit contains millions of tons of copper. The study indicates that a deeply buried nuclear explosive can adequately fracture a portion of the deposit for the test. Based on previous test work, the ore mineralization should respond favorably to leaching recovery methods. The study also concludes that an effective experiment at the Safford site can be designed which would satisfy both the technical objectives and meet all safety requirements.

Possible radioactive contamination of the copper is considered to be a manageable problem both for the experiment and for general application. Radioactivity in the leaching solutions should be at low enough levels that shielding should not be required for personnel protection.

The report recommends a field experiment to test the concepts. The estimated total cost of an experimental test, including one year of continuous leaching, is $13,175,000. It is emphasized in the report that Sloop is an experiment to test the combining of two technologies into a new mining concept and that additional experiments may be necessary before the technique can be developed into general commercial practice.

A. General

The gradual evolution of the development of explosives has historically led to new and more efficient applications of blasting in the modern mining industry. Since the crude beginning with the discovery of black powder, the entire field of explosive technology has steadily improved. The significant resulting effect on costs has contributed to the mining of increasingly lower grade mineral deposits. With the atomic age more than two decades old, the utilization of the world's most powerful explosive offers the promise of further substantial reductions in the costs of mining the earth's mineral resources.

Fracturing copper bearing orebodies with nuclear explosives and leaching the copper minerals fron, the ore in place appears to present a low-cost method for recovering copper from deposits that are not economically minable by other methods. Development of such a method could offer the means for recovering millions of tons of copper for the uses of industry and the Nation.

The Sloop feasibility study was undertaken as a detailed investigation of this concept. The investigations are a joint effort of the Atomic Energy Commission, the U.S. Bureau of Mines and the Kennecott Copper Corporation. This report presents the conclusions of the studies by these organizations and includes an evaluation of a proposed test site located near Safford, Arizona.

The Lawrence Radiation Laboratory, which is operated for the Atomic Energy Commission by the University of California, provided the technical design of the pre- and post-shot exploration program, the nuclear detonation, and the prediction of hazards involved in the experiment described in this report. The Nevada Operations Office of the AEC provided the operational safety plan and the preliminary cost estimate. The Oak Ridge National Laboratory provided consulting services to determine methods of preventing or eliminating radioactive contamination of the copper. The USBM investigated the domestic reserves of copper orebodies that could utilize such an in-place (in-situ) mining and leaching method. The Bureau of Mines also explored the projected impact on the Nation's available copper resources which might result from development of this technique. Kennecott Copper Corporation provided the geologic and environmental studies of the proposed test deposit and developed the design for the leaching portion of the

experiment.

The primary purpose of this study report is to provide Kennecott, the AEC and the USBM with information upon which to evaluate this concept.

No authorizations or approvals have been given or sought for initiating work on the experiment described in this study report. Before such an experiment could be initiated an acceptable proposal would be required by the AEC from Kennecott, and subsequently would involve a number of government approvals and authorizations. The first step must be a determination by the policy making bodies of both the AEC and Kennecott that this experiment is a worthwhile project in the Nation's interest for sponsorship under the Plowshare Program.

B. The Plowshare Program

The Plowshare Program was established by the U.S. Atomic Energy Commission in 1957, to investigate and develop peaceful uses for nuclear explosives. Primary research and development for the Atomic Energy Commission is carried out by the Lawrence Radiation Laboratory. Other research work is conducted by the Oak Ridge National Laboratory; the Sandia Corporation; the Los Alamos Scientific Laboratory; the Savannah River Laboratory; the U.S. Bureau of Mines; and the U.S. Geological Survey. In addition to government organizations, several private industrial companies have cooperated with the AEC in carrying out Plowshare research work.

As a result of the nuclear experiments conducted by the AEC a significant body of information and understanding pertaining to the physical effects which are produced by nuclear explosions in various types of rock has been accumulated. 3, 4, 5, 6, 7, 8, 10 The data obtained from these field experiments, when combined with laboratory experiments and theoretical investigations, provides the Plowshare Program with the capability to predict certain physical effects of a nuclear explosion with fair accuracy. While such data provides a substantial base for screening possible industrial applications, only an actual field experiment with the explosive in the specific industrial situation can effectively evaluate a proposed application.

C. Availability of Explosives

At the present time the AEC is not authorized to supply explosives and the required support services on a commercial basis. The AEC can, however, under the Atomic Energy Act of 1954, utilize nuclear explosives in cooperative research and development