Solvent extraction of uranium from acidic sulfate media by Alamine~R 336: computer simulation and optimization of the flow-sheets

摘要

BACKGROUND: A series of nine conventional and non-conventional flow-sheets have been considered for the recovery ofuranium from acidic sulfate solution by liquid-liquid extraction with 0.146 mol 1-1 Alamine~R 336 in kerosene modified with5% w/w 1-tridecanol and stripping with a 199 gL~(-1)Na_2CO_3solution. The reference flow-sheet was a classical counter-currentconfiguration with four mixers-settlers in the extraction stage and three mixers-settlers in the stripping stage. The othersflow-sheets possessing a total of eight mixers-settlers are unusual combined solvent extraction flow-sheets with one or twoindependent extraction stripping loops and with one or two feed inlets. RESULTS: The configuration of the flow-sheets strongly influences the extraction performance of the process depending onthe working conditions (feed, stripping and solvent flow rates). The presence of two independent extraction-stripping loopsmay allow the delay of the saturation phenomenon encountered in the conventional flow-sheet and thus, to operate at higherfeed flow rates without loss of performance, as far as the residual fraction in the raffinate and the concentration factor in thestripping solution are concerned. Furthermore, the presence of a modification in the non-conventional flow-sheets with twoindependent extraction -stripping loops and two feed inlets leads to interesting configurations for uranium recovery from lessconcentrated solutions, such as heap leach solutions. CONCLUSION: The use of non-conventional flow-sheets is interesting as it allows the process of uranium (VI) recovery byliquid-liquid extraction to be improved.