Application of Computers in the Analysis of in situ Leach Mining Hydrology

An investigation of in situ leaching hydrology is being conducted by the US Bureau of Mines at the Cyprus Casa Grande mine. Desktop microcomputers and relevant softwares are used to advance understanding of the complex hydrologic setting that exists during leaching of a fractured copper ore deposit. The ongoing investigation has thus far involved the application of seven different software packages. Four of these were developed at the Bureau of Mines, Twin Cities Research Center. Specialized data acquisition and data reduction software is used to generate an extensive hydrologic database, and to isolate intervals of steady-state flow conditions. Analytic element modeling software is used to describe spatial and temporal variations in hydraulic conductivity in the deposit during leaching, and to pose a transmissivity inverse problem. A statistical package is used to describe the magnitude of changes in transmissivity that occur during leaching, and to isolate two major influences: variations in in situ stress and geochemical precipitation. A geostatistical package is used to solve the transmissivity inverse problem and to krig the transmissivity data, as a basis for developing a continuum model of heterogeneities in the deposit A finite element modeling package is used to ascertain the influence of unsaturated conditions on hydraulic conductivity. The potential of an object-oriented (computer-aided design) interface for a hydrology model is also illustrated. The integration of these software packages is facilitated by the desktop computing environment that exists at the Bureau’s Twin Cities Research Center. This environment includes desktop microcomputers with multitasking operating system capability, a common storage buffer accessible from within all software applications, and a local area network (LAN) which links the computers to a large database containing all of the mine hydrologic and geochemical data. In the future, a microcomputing environment that facilitates the integration of results from several different software packages, including hydrologic, geochemical, and geomechanical models, will be most valuable in building insight and understanding of this complex mining system.