Processing High-Level Liquid Waste by Super-High-Temperature Method, (III) Reactions of Platinum Metal Oxides with Titanium Nitride
The process constituting the elements of the method for treating high-level liquid waste with addition of reducing agent at temperatures above 1, 873K were examined applying thermogravimetry and X-ray diffractometry to sample mixtures of the platinum metal oxides RuO<SUB>2</SUB>, Rh<SUB>2</SUB>O<SUB>3</SUB>, PdO and of Re<SUB>2</SUB>O<SUB>7</SUB>, with and without addition of TiN as reducing agent. The addition of TiN reducing agent proved to induce reduction of the platinum metal oxides at temperatures far below those of thermal decomposition occurring in the absence of reducing agent. The presence of reducing agent further proved to reduce Re<SUB>2</SUB>O<SUB>7</SUB> to ReO<SUB>3</SUB> at 373K, to ReO<SUB>2</SUB> at 773K and to Re metal at 1, 073K. At around 773K disproportionation reconverted part of the ReO<SUB>3</SUB> formed at 373K to ReO<SUB>2</SUB> and Re<SUB>2</SUB>O<SUB>7</SUB>. Thus, sublimation of the Re<SUB>2</SUB>O<SUB>7</SUB> in starting material which occurs at 523K in the absence of TiN was eliminated, and occurred only at 773K on the Re<SUB>2</SUB>O<SUB>7</SUB> that was regenerated at that temperature by disproportionation of the converted ReO<SUB>3</SUB>. Alloys of Ru, Rh and Pd resulting from the above treatment with TiN proved to agree with what is indicated from phase diagrams. Among the alternative compounds existing in the Rh-Ti and Rh-Ti binary systems, however, solely Ru-Ti proved to have been produced.
- Journal of nuclear science and technology
Journal of nuclear science and technology 33(11), p.879-885, 1996-11-25
Atomic Energy Society of Japan