Modern methods of solution mining are typically accompanied by gains and losses of mass via reagent consumption by rock-forming minerals and subsequent clay-mineral formation. A systematic approach to alleviation of such problems involves the application of leach solutions which are in equilibrium with the host-rock minerals but in disequilibrium with the ore-forming minerals. This steady state can be achieved by solution composition adjustments within the systems K₂O-Al₂O₃-SiO₂-H₂O and Na₂O-Al₂O₃-SiO₂-H₂O. Uranium ores from the Grants mineral belt of New Mexico containing 0.15 to 1.0% U₃O₈ were collected for investigation. Small-scale (<= 1 kg) column leaching experiments have been conducted to compare results of conventional leaching systematics with those obtained with solutions in equilibrium with the matrix minerals. Application of these principles will have considerable bearing on future in-situ leaching of uranium ores.

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