Extraterrestrial Resources: Implications From Terrestrial Experience STEPHEN L. GILLETT & DAVID L. KUCK SUMMARY Terrestrial mining experience indicates that the overwhelming criterion for a potentially economic deposit is its recoverable concentration of the desired mineral or element. Recovery can be based on contrast in physical and/or chemical properties, but processes based on physical properties are typically less expensive. As several of these processes are usually used in sequence, they have a profound effect on extraction costs. These criteria will also apply to extraterrestrial resources. Although the extreme cost of access to space makes even ordinary materials extremely valuable, this inaccessibility also makes capital and maintenance coSts extremely high. The following four development stages will apply, especially with the additional unknowns of an extraterrestrial environment: (1) Exploration for the highest grade of the mineral or element desired. Because the extraction plant must be simple, cheap, and rugged to minimize capital and maintenance costs, high grade is extremely important. (2) Laboratory testing of various physical and/or chemical separation techniques on the possible ore to determine if the material can indeed be recovered economically. (3) A pilot plant test, in which a large sample is dug from the deposit to determine excavation rates, power requirements, and equipment wear, and then run through a pilot mill. Pilot plant testing must be carried out at increasing scales, but several trials are generally necessary at each scale before the size of operations can be increased. Moreover, pilot testing is necessary for each new mineral deposit. (4) Last is the full-scale mine and plant start-up. New problems invariably occur at this point, but they can be kept to a minimum if the pilot plant tests were realistic. If such a development plan is followed rigorously, major cost overruns, with their potentially disastrous effects on resource development, may be avoided. Introduction The overwhelming criterion of a potentially economic deposit is its economically recoverable concentration of the desired mineral or element (e.g., Gillett, 1991). This criterion stems from the difficulty of separating elements, due to the compositional complexity and heterogeneity of natural materials, which seems Department of Geology, Mackay Schools of Mines, University of Nevada, Reno, NV 89557. Geological & Mining Consultant, P.O. Box 369, Oracle, AZ 85623.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==