Dissolution and Separation of Aluminum and Aluminosilicates

Abstract

Selection of an aluminum alloy for target cladding affects post-irradiation target dissolution and separations. Recent tests with aluminum alloy 6061 yielded greater than expected precipitation in the dissolver, forming up to 10 wt.% solids of aluminum hydroxides and aluminosilicates. Aluminosilicate dissolution presents challenges in a number of different areas, including metals extraction from minerals, flyash treatment, and separations from aluminum alloys. We present experimental work that attempts to maximize dissolution of aluminum metal in caustic, along with silicon, magnesium, and copper impurities, through control of temperature, the rate of reagent addition, and incubation time. Aluminum phase transformations have been identified as a function of time and temperature, using X-ray diffraction. Solutions have been analyzed using wet chemical methods and X-ray fluorescence. These data have been compared with published calculations of aluminum phase diagrams. Approaches are given to enhance the dissolution of aluminum and aluminosilicate phases in caustic solution.

Keywords:

• aluminosilicate dissolution
• aluminum alloy 6061
• plutonium for RTGs

ACKNOWLEDGEMENTS

The authors want to thank Dr. Michael Hu for the particle size analysis, Dr. Roberta Meisner for the XRD analysis, and Drs. Huimin Luo and Laetitia Delmau for reviewing the manuscript.

Notes

¹ Experiments 1-6 are the small scale tests that were discussed in Section titled “Small Scale Survey Experiments.” They have not been included in Table 4 as fewer analyses were performed than for the larger scale tests.

Additional information

Funding

This work was supported by the Pu-238 Production Project. This manuscript has been authored by UT-Battelle, LLC, under Contract No. DE-AC0500OR22725 with the U.S. Department of Energy.