Characteristics of uranium ores from Tono Mine viewed from ore dressing and refinement

The concentration of uranium was found in the Tsukiyoshi deposits of Tono Mine in Japan, where uranium is adsorbed by zeolite. This type of the enrichment mode in such large scale seems to be the first case not only in Japan but also in the world. Experiment was performed to study the uranium adsorption by zeolite, and it was found that the maximum adsorption rate was seen in the range of pH4 - 8.5 of solution, uranium distribution coefficient was about 700, and the maximum amount of adsorption was 0.9 - 1%. From these results, the processes of ore formation are presumed in this paper. Leaching test was also carried out, and it was concluded that leaching is rather easy with either sulfuric acid or alkalies, and 91% of leaching rate was obtained by six hour treatment with the acid and 80% by twenty hour treatment with the alkalies. The conditions of the ore leaching test are summarized in a table. (Aoki, K.)