Abstract
Based on design of uranium recovery process from sea water, total cost for uranium production was estimated. Production scale of 1,000 ton-uranium per year was supposed, because of the big demand for uranium in the second age, i. e., fast breeder reactor age.
The process is described as follows: Fluidized bed of hydrous titanium oxide (diameter is 0.1 mm, saturated adsorption capacity is 510 μg-U/g-Ad, adsorption capacity for ten days is 150 μg-U/g-Ad) is supposed, as an example, to be utilized as the primarily concentration unit. Fine adsorbent particles can be transferred as slurry in all of the steps of adsorption, washing, desorption, washing, regeneration. As an example, ammonium carbonate is applied to desorb the adsorbed uranium from titanium oxide. Then, stripping method is adopted for desorbent recovery. As for the secondary concentration, strong basic anion exchange method is supposed.
The first step of process design is to determine the mass balance of each component through the whole process system by using the signal diagram. Then, the scale of each unit process, with which the mass balances are satisfied, is estimated by detailed chemical engineering calculation. Also, driving cost of each unit operation is estimated. As a result, minimum total cost of 160,000 yen/kg-U is obtained. Adsorption process cost is 80 to 90% of the total cost. Capital cost and driving cost are fifty-fifty in the adsorption process cost. Pump driving cost forms a big part of the driving cost.
Further concentrated study should be necessary on the adsorption process design. It might be important to make an effort on direct utilization of ocean current for saving the pump driving cost.
