A technique was developed for simulation of heap leaching uranium ores in 2-ft-diam columns constructed such that ores as coarse as minus 4-in could be treated in bed depths from 8 to 18 ft with test condition variations. The technique consisted of the separate steps of ore preparation, column loading, charge wetting, leaching, washing, and residue recovery. For the ores studied, sulfuric acid was found to be generally superior to alkaline lixiviants. The rate of uranium extraction by acid leaching proved to be primarily a function of percolation rate, alkalinity of the ores, and oxidant requirements of the ores. Column leaching was closely comparable to field-scale heap leaching terms of uranium extraction rate and recovery results. Acid and oxidant requirements were lower for the field-scale operation. All column tests, as well as the field-scale heap, achieved in excess of 96-pct uranium extraction on a Bear Creek, Wyoming, ore.