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Barium Carbonate-Metal Oxide 혼합물에 의한 휘발성 루테늄 제거
Volatile Ruthenium Removal by the Mixture of Metal Oxide and Barium Carbonate
HWAHAK KONGHAK, August 1988, 26(4), 351-363(13), NONE
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Abstract
235U 핵연료 재처리가공이나 핵폐기물 처리시 휘발된 루테늄을 제거하는데 있어서 휘발된 루테늄을 제거할 뿐만 아니라 뒤이어 일어나는 재휘발을 방지하기 위하여 안정한 화합물로 변형시키는 것이 중요하다. 하소온도와 공기유속을 변화시켜 모의루테늄 질산폐액을 증발시키는 동안 하소로 off-gas로부터 발생된 루테늄종（species）의 휘발도를 관측하였다. Fe2O3, TiO2, MnO2, BaCO3와 BaCO3-Fe2O3, BaCO3-TiO2, BaCO3-MnO2 혼합물 등의 흡착제를 사용하여 기상 루테늄종을 제거하였고 각 흡착제에 대한 제거율을 측정, 비교하였다. 하소로 off-gas로부터 발생된 휘발하는 루테늄을 제거하기 위하여 사용된 흡착제중에서 BaCO3-Fe2O3, BaCO3-TiO3, BaCO3-MnO2 등의 혼합물이 각각 500 ℃-750 ℃, 650 ℃, 550 ℃에서 휘발하는 루테늄을 효율적으로 제거하였다. 루테늄은 금속산화물과 바륨 카보네이트와의 혼합물과 같은 담체위에 결합되어 RuO4로의 휘발이 효과적으로 방지될 수 있고 500 ℃ 이상의 온도에서 안정한 혼합금속 루테네이트를 생성하도록 흡착제와 자발적으로 반응할 수 있는 것으로 생각된다. UV와 IR분석결과 휘발하는 루테늄종은 NOx의 존재하에서 RuO4보다는 더 안정한 nitrosyl ruthenium gas complex라고 생각된다. 그러므로 흡착메카니즘은 nitrosyl ruthenium complex가 흡착되고 루테늄 위의 nitric oxide촉매분해반응에 의해 N2가 탈착되면서 안정한 상태로 전환하는 것으로 추론된다.
In removing the ruthenium volatilized during the 235U nuclear fuel reprocessing and waste treatment, it is important to not only to trap volatilized ruthenium but also to transform it into stable compound to prevent subsequent revolatilization.
A calcination temperature and air velocity were varied to observe the volatility of ruthenium species from calciner off-gas during the evaporation of simulated ruthenium nitric acid solution. The adsorbents such as ferric oxide, titanium dioxide, manganese dioxide, barium carbonate and the mixtures of barium carbonate and above metal oxide were used to remove gaseous ruthenium species and also removal efficiencies for each adsorbents were measured. The mixture adsorbents removed effectively volatiole ruthenium.
It is considered that ruthenium can be effectively preverted from volatilizing as RuO4 by being bonded to a support such as the mixture of barium carbonate and the metal oxide and that volatile ruthenium species spontaneously can react with the above adsorbents to yield the stable mixed metal ruthenates at temperatures over 500 ℃. The spectra of UV-visible and IR may be suggested that volatile species is a more stable nitrosyl ruthenium gas complex than RuO4 in the presence of NOx. There fore the mechanism of adsorption is deduced that the nitrosyl ruthenium complex is adsorbed, then it converts to the stable state, N2 being desorbed by catalytic decomposition of nitric oxide on ruthenium.
A calcination temperature and air velocity were varied to observe the volatility of ruthenium species from calciner off-gas during the evaporation of simulated ruthenium nitric acid solution. The adsorbents such as ferric oxide, titanium dioxide, manganese dioxide, barium carbonate and the mixtures of barium carbonate and above metal oxide were used to remove gaseous ruthenium species and also removal efficiencies for each adsorbents were measured. The mixture adsorbents removed effectively volatiole ruthenium.
It is considered that ruthenium can be effectively preverted from volatilizing as RuO4 by being bonded to a support such as the mixture of barium carbonate and the metal oxide and that volatile ruthenium species spontaneously can react with the above adsorbents to yield the stable mixed metal ruthenates at temperatures over 500 ℃. The spectra of UV-visible and IR may be suggested that volatile species is a more stable nitrosyl ruthenium gas complex than RuO4 in the presence of NOx. There fore the mechanism of adsorption is deduced that the nitrosyl ruthenium complex is adsorbed, then it converts to the stable state, N2 being desorbed by catalytic decomposition of nitric oxide on ruthenium.
