Ural Federal University—UrFU, member of the Nedra Consortium—scientists have figured out how to process radioactive uranium-containing sludge. The uranium content in the waste was merely 0.1%.
It is the kind of waste that requires large-scale recycling, accumulated in huge quantities at the nuclear industry enterprises. The research team has already tested the technology that will provide uranium to the nuclear industry, UrFU Press Office informs.
"Our method allows to solve several important problems when applied on an industrial scale: to process radioactive waste and obtain valuable uranium and associated useful materials," explains Ksenia Nalivaiko, a graduate student and engineer at the Department of Rare Metals and Nanomaterials at UrFU.
The new method consists of three stages. At the first stage, sludge samples are subject to leaching with sulphuric acid. The researchers found that the most effective uranium leaching from waste is when the sulphuric acid concentration is 200 g/l, and the solution temperature is maintained at 80 °C for four hours. In this case, the degree of uranium extraction reaches maximum values and amounts to 99.98%.
Next, the obtained uranium-containing sulphuric acid solution is passed through ion-exchange resins of various industrial grades. The resin is washed with distilled water, and uranium is desorbed from the saturated ion-exchange resin by a mixed sulphuric acid and ammonium nitrate solution. Due to this, the uranium concentration increases 3–8 times.
Finally, neutralisation of the concentrated uranium solution results in the concentrated solid uranium precipitate. Its uranium content is 68.54%; the content of impurities meets the international quality standard ASTM C967-13.
Aside from uranium, the technology helps obtain gypsum, carbonate and calcium fluoride, silicon oxide, thaumasite—all having multiple uses in the industry.
Let us recall that last April, UrFU presented a new technology for producing hydrochloric acid and alkali. The core of this method is in processing liquid waste accumulating over potash fertiliser production—a sodium chloride solution. The strength of the solution exceeds that of seawater by almost ten times, with the sludge containing unextracted residues of potash salt and rock material.
