A Study Of Oxidation And Cyanide As An Oxidation Catalyst In Pressure Leaching Of Uranium ? Introduction

Early studies in the carbonate leaching of uranium ores led to the investigation of pressure leaching as a method to enhance the dissolution of the metal values in this system. The initial investigations conducted at the University of British Columbia supplemented by the work done by the group at the A.E.C. Grand Junction pilot plant, all established the higher efficiency and better economics of the alkaline pressure leaching system. This work was conducted either in laboratory autoclaves using oxygen overpressures, or in pilot plant sized horizontal autoclaves with air as an oxidant. Both of these testing vehicles utilized agitation provided by relatively high speed impellers (300 to 700 rpm), which apparently enhanced the oxidation of the uranium to the hexavalent state. The installation of vertical autoclaves on a production scale, which through design considerations require relatively slow agitator speeds (68 rpm), led to the studies of the utilization efficiency of the air addition and the use of catalytic type oxidants to effect a greater usage of the oxygen added through the aeration system. In addition to investigating the effects of the chemical additives, studies were also conducted on the effect of different impeller configurations on the extraction of uranium, which in itself is a measure of oxidation efficiency. The material presented in this paper was compiled in the Ambrosia Lake district of New Mexico, and the majority of the data was obtained in the Homestake- Sapin Partners mill, located at Grants, New Mexico.