Acid leaching of uranium from a low-grade Indian uranium ore deposit

This paper discusses the leaching behavior of uranium from a low-grade unconformity-related uranium ore occurring in the northwestern part of the Kadapa basin in southern India. This is the major unconformity-related deposit located in India. The U3O8 assay of the ore is about 0.06%. The chief uranium-bearing phase is uraninite, and the ore also has a minor quantity of coffinite. The carbonaceous matter, as well as the porous titanium phases occurring in the ore, is also radioactive. The major gangue mineral is quartz, followed by minor quantities of sericite, chert, chlorite and feldspar. Detailed parametric variation studies were carried out on the ore to optimize conditions for sulfuric acid leaching of uranium values. Based on the laboratory results, preliminary design criteria were developed for process engineering. About 82% of uranium values were leached under conventional atmospheric leaching conditions. Uranium values present in the carbonaceous matter and the other refractory phases were solubilized only after roasting the leach residue. This process improved the overall leach recovery to about 89%. Minerals & Metallurgical Processing, 2012, Vol. 29, No. 3, pp. 165-168. An official publication of the Society for Mining, Metallurgy, and Exploration, Inc.