Table 5.19 lists the uranium mills operating in the United States in January 1977 and their capacity, as reported by the Grand Junction Office of the U. S. Energy Research and Development Administration [Ш]. Table 5.19 summarizes the processes used in the mills, when such information is available from a May 1975 report from the Oak Ridge National Laboratory [S2] and other industry sources. As uranium milling is a dynamic industry, with frequent changes in process technology and mill capacity, Table 5.19 serves more to illustrate the diversity of milling processes than to provide an invariant listing.

Part 1 of Table 5.19 lists mills using carbonate leaching. There is no standard process for recovery of uranium from carbonate leach liquors. The trend is away from precipitation with NaOH as crude Na2U207 toward further purification as by UO4 precipitation at Rio Algom or by ion exchange followed by precipitation as (NH4)2U207 at George West.

Part 2 of Table 5.19 lists mills using acid leaching and solvent extraction. All mills for which process information is available use a long-chain tertiary amine, Alamine-336 or Adogen-364, as extractant, with general features illustrated in Sec. 8.6.

Part 3 of Table 5.19 lists mills using acid leaching and anion exchange. The three types of contactors and the different eluting and final treating processes are described in Sec. 8.7.