Recovery of Palladium VIA a Vitrification Process

Abstract

The Savannah River National Laboratory (SRNL) has developed a process to recover, decontaminate, and reuse Pd from a radioactive waste (referred to as Pd/K) resulting from the tritium production process. The feasibility of efficiently recovering Pd was demonstrated through a series of tests based on the use of a simple additive followed by thermal processing and mechanical separation. More specifically, 10 mole borax (Na 2 B 4 O 7 • 10H 2 O) was added to deuterium-cycled Pd/K material on a 1:1 mass basis and heated at 1575°C for 4 hours. The diatomaceous earth reacts with the borax to produce a borosilicate glass product. At temperature, the Pd melts and coalesces to form an ingot which settles to the bottom of the crucible due to density differences. After cooling, the glass can be mechanically fractured and the Pd ingot separated and recovered. Based on the initial weight of Pd/K material used, the weights of the recovered Pd ingots, and assuming the Pd/K was 40 - 50% Pd by weight, it was estimated that approximately 95 - 99% of the Pd was recovered. The recovered Pd was determined to be substantially free of deuterium after isotopic exchange with high purity protium meeting programmatic objectives.