Optimization of low-temperature pyrolysis process equipped with a two-stage non-flame oxidation system for the treatment uranium-bearing spent TBP

This study develops new pyrolysis process that can safely burn out organic constituents in the uranium-bearing spent TBP without problems associated with phosphate condensation. Based on the results of thermal analysis of spent TBP, we proposed a low-temperature pyrolysis process equipped with a two-stage oxidation system. The proposed process mainly consists of a low-temperature pyrolyser, steam reformer and catalytic oxidizer. The optimum operating conditions for the pyrolyser were determined as a temperature of 530 K and LHSV of 0.2 h(-1), based on the thermal analysis of spent TBP. A parametric model study of the steam reformer and catalytic oxidizer was performed to determine their optimized design and operating conditions. A bench-scale pyrolysis process with a capacity of 1 kg spent TBP per hour was installed based on the results of the optimization study. We successfully demonstrated the improved performance of phosphate retention in the pyrolysis residue and that of destruction and oxidation of organic constituents in the spent TBP under the optimized conditions. (C) 2015 Elsevier B.V. All rights reserved.