Some recent improvements in a uranium processing pilot-plant at the Ningyo-toge mine

Since 1964 the uranium processing plant at the Ningyo-toge mine has been modified and extended. In 1970 an ammonium diuranate (ADU) producing process was added to the plant, and a pilot plant with an ore-processing capacity of 50t/d was brought into operation. As a result of this operation the process which produces high-purity ADU was confirmed. An electrolytic reduction plant for the pilot operation was constructed by the Asahi Chemical Industry Co. in 1972. Experiments on the reduction of uranyl chloride solution were carried out with good results. Hydrofluorination facilities were added to the plant in 1974 and experiments on the hydrofluorination of UCl4 started. The experiments also studied the characteristics of hydrated UF4. Preliminary experiments on dehydration from hydrated UF4 were carried out to determine the dehydration conditions and the properties of the UF4 in the laboratory at the Tokai Works, PNC. The results of these dehydration experiments and UF4 conversion tests were excellent. (author)