In-situ leaching of Crownpoint, New Mexico Ore. VI--The section 9 pilot test

Mobil has successfully recovered uranium by insitu leaching from a depth of 2000 feet in the Westwater Canyon Member of the Morrison Formation near Crownpoint, New Mexico. This was the deepest in-situ uranium leach successfully carried out in the United States, and the first in-situ uranium leach accomplished in New Mexico. Using a hydrogen peroxide/alkaline bicarbonate leachate, an average uranium level of slightly greater than 100 ppm was produced during the 10 month leaching phase. The leachate flow was confined to the selected ore zone within the Westwater Canyon Member by careful reservoir management. High levels of molybdenum were also produced during leaching. This complicated the functioning of the ion-exchange and precipitation circuits, but methods to control these problems were evolved. The leaching demonstration period was insufficient to fully extract the uranium, and leaching was terminated after only a part of the uranium resource was recovered so that restoration could proceed. During the first 12 months of restoration, all 27 water quality parameters (New Mexico state standards) except molybdenum were reduced below the required limits. In commercial operation, both uranium and molybdenum would be fully depleted during the leaching phase and should present little problem during restoration. The relatively lowmore » front-end capital requirements of in-situ leaching, with its potentialities for development in a stepwise, modular manner, reduce the risk of its implementation in an unstable yellowcake market environment.« less