1969 Mining Simulator Eliminated Years of Underground Work Long years spent in underground planning were saved by a big, 7 foot by 11 foot, electrical gadget. Its face covered with 1500 telephone jacks, and the instrument simulated a plan or top view of an underground tabular ore deposit. The "Mines Stress and Convergence Analog" computer, as the instrument was called, was demonstrated at a Rock Mechanics Short Course, conducted in cooperation with the department of conferences and institutes, General Extension Division, at the University of Minnesota. "A whole range of possibilities, in planning the layout and sequence of an underground mine, which ordinarily would take years of actual excavation work, could be explored in a few minutes through simulation with the mine stress and convergence analog," Professor Neville Cook of South Africa, a guest lecturer at the University, explained in demonstrating the device. The first prototype of the simulator, or analog, built by Cook at the Mining Research Laboratory of the South African Chamber of Mines, was used to plan many major gold Mines in South Africa. A "more sophisticated model," built under the direction of Associate Professor David Lacabanne of the School of Mineral and Metallurgical Engineering at the University of Minnesota, was demonstrated at a short course. This mode was the only one of its kind in the United States. Each jack on the face of the instrument represented an underground area or block of earth. When the jack was pulled out, this was equivalent to having "mined out" or removed all the earth from the area. "Change in current and voltage simulate the changes in underground stress and convergence of openings," Professor Charles Fairhurst, former director of various rock mechanics research programs and former head of the School of Mineral and Metallurgical Engineering, explained. "Experience with a certain type of mining problem is thus gained before mining begins. Alternative answers to various mining approaches, which an engineer might be planning to use are provided in advance, forcing him to examine his reasons for any given approach." The most basic design problem in underground excavation—how to extract as much ore as possible, yet leave enough orebody to prevent collapse before mining can be completed—was simplified considerably, if not pre-solved, with this computer method. The more often these computer results are compared with underground observations, the more useful the computer became in actually predicting and planning what will happen in mining. From The Mines Magazine February 1969