A laboratory method for the simulation of in-situ leaching of uranium was developed under contract to the Interior Department’s Bureau of Mines. Simulation tests using sulfuric acid, ammonium bicarbonate and sodium carbonate as reagents, and hydrogen peroxide as oxidant were carried out with representative ores from Texas and Wyoming. The tests not only yielded recovery rates of uranium and permeability changes, but also qualitative inferences on the chemical and physical phenomena which occur underground. Leaching with basic solutions was found to be kinetic constrained and with acid solutions, equilibrium constrained. The rapid permeability changes observed when leach solutions were introduced, were probably caused by gas blockages in the packing. Precipitation of calcite or gypsum and the reaction of clay to leach solutions had slow and gradual effect on the packing permeabilities.
The In-Situ Simulation System
The following features were considered in arriving at an acceptable design:
- Ore sample container of representative geometry (cylindrical, rectangular slab, etc.) capable of operating at temperature and pressure constraints occurring in in-situ leaching, o Adequate sampling ports for obtaining solution and ore samples for analysis and characterization.
- Sufficient Instrumentation to monitor all operating parameters (flow, pressure, temperature, etc.) and to allow identification of the state