Thermal Decomposition of Potassium Titanium Hexacyanoferrate(II) Loaded with Cesium in a Fixed Bed Calciner

• Published in: Chinese journal of chemical engineering 2007-03, Vol.15 (2), p.184-189
• Main Authors: FENG, Xiaogui, JING, Shan, WU, Qiulin, CHEN, Jing, SONG, Chongli
• Format: Article
• Language: English
• Subjects: agglomerate; fixed bed calciner; potassium titanium hexacyanoferrate (II) (KTiFC); thermal decomposition
• ISSN: 1004-9541; 2210-321X
• DOI: 10.1016/S1004-9541(07)60056-1

The thermal decomposition of potassium titanium hexacyanoferrate(II) (KTiFC) loaded with cesium (referred to as Used Exchanger, or UE) was studied at different flow rate of air in a fixed bed calciner. The calcination process consisted of four stages: ambient temperature—180°C (stage I), 180–250°C (stage II), 250–400°C (stage III), and constant 400°C (stage IV). The most intense reaction occurred in stage II. The rate of thermal decomposition was controlled, depending on the O 2 flux, by O 2 or CN concentration in different stages. Results from differential thermal analysis (DTA) showed that the calcination reaction of the anhydrous UE was exothermic, with an approximate heat output of 4.6kJ.g -1, which was so large to cause the possible agglomeration of calcined residues. The agglomeration could be avoided by enhancing heat transfer and controlling the O 2 flux. It was found that there was no cyanides in the calcined residues and no CN-bearing gases such as HCN and (CN) 2 in the off-gas. It seemed that the catalytic oxidation furnace behind the fixed bed calciner could be cancelled.