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HWAHAK KONGHAK,
Vol.37, No.1, 14-20, 1999
Vol.37, No.1, 14-20, 1999
비등온 열중량법에 의한 AUC분말의 열분해 특성해석
Thermal Decomposition Characteristics of AUC Powder by Non-Isothermal Method
AUC(ammonium uranylcarbonate) 분말의 배소·환원에 대한 연구를 수소분위기에서 TG-DTA를 사용하여 수행하였다. AUC 분말의 열분해 과정 중 다양한 상 변화 특성을 XRD로 확인하였다. AUC 분말의 열분해 반응 메카니즘은
(NH4)4[UO2(CO3)3]→UO3+3CO2+4NH3+2H2O
3UO3+H2→U3O8+H2O
U3O8+H2→3UO2+H2O
와 같은 3단계로 나타났다. AUC 분말의 배소·환원 속도는 비등온 열중량법으로 구하였으며, 데이터해석은 Osawa 방법과 Zsako 방법으로 구하였는데 다음과 같다.
(NH4)4[UO2(CO3)3]→UO3+3CO2+4NH3+2H2O
3UO3+H2→U3O8+H2O
U3O8+H2→3UO2+H2O
와 같은 3단계로 나타났다. AUC 분말의 배소·환원 속도는 비등온 열중량법으로 구하였으며, 데이터해석은 Osawa 방법과 Zsako 방법으로 구하였는데 다음과 같다.
| Reaction | Mechanusm | E(Kcal/mole) |
|---|---|---|
| AUC→UO3 | 2nd nucleation and growth | 19.5 |
| UO3→U3O8 | 3nd nucleation and growth | 30.12 |
| U3O8→UO2 | 4th nucleation and growth | 31.43 |
Calcination and reduction of AUC(ammonium uranylcarbonate) have been carried out by using TG-DTA in H2 atmosphere. Phases of various intermediates obtained during thermal analysis of AUC were confirmed by XRD. As results, AUC was calcined and reduced by three steps as follows;
(NH4)4[UO2(CO3)3]→UO3+3CO2+4NH3+2H2O
3UO3+H2→U3O8+H2O
U3O8+H2→3UO2+H2O
The calcination and reduction kinetics of AUC have been also determined by non-isothermal method and the analysis of kinetic data was made by Osawa and Zsako methods. The results were as follows;
(NH4)4[UO2(CO3)3]→UO3+3CO2+4NH3+2H2O
3UO3+H2→U3O8+H2O
U3O8+H2→3UO2+H2O
The calcination and reduction kinetics of AUC have been also determined by non-isothermal method and the analysis of kinetic data was made by Osawa and Zsako methods. The results were as follows;
| Reaction | Mechanusm | E(Kcal/mole) |
|---|---|---|
| AUC→UO3 | 2nd nucleation and growth | 19.5 |
| UO3→U3O8 | 3nd nucleation and growth | 30.12 |
| U3O8→UO2 | 4th nucleation and growth | 31.43 |
Keywords:
Ammonium Uranylcarbonate; Calcination; Reduction; Non-Isothermal Method; Hydrogen Atmosphere
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