Partic. vol. 22 pp. 107-113 (October 2015)
doi: 10.1016/j.partic.2014.11.005

Decomposition of ammonium sulfate residue in a high solid/gas ratio suspension state with an industrial-scale reactor system (production line)

Qi Li^a, Delong Xu^a, Yanxin Chen^a, Yanfei Yao^a, Zhi Sun^b, Songxiong Ding^a,c,*

songxiong.ding@uia.no

Abstract

Ammonium sulfate residue is a particulate solid and is produced during the manufacture of ammonium sulfate fertilizer. The residue used in this study contained a large portion of calcium carbonate, from which active lime (CaO) was recovered via thermal decomposition. We used a purpose-built device to decompose the residue in a semi-suspension state. We found that CaO had the highest activity when residue was decomposed at 850–900 °C. Our experiments indicated that ammonium sulfate residue should be decomposed in a suspension state to produce active CaO. Based on our laboratory test findings, an industrial-scale production line with a high solid/gas ratio in a suspension state was devised. The optimal operating conditions for the decomposition of the ammonium sulfate residue to produce high quality CaO were also investigated. We found that the CaCO₃ decomposition rate was high and the CaO product was highly active, averaging 170 s by the citric acid method. Morphology measurements showed that the CaO product had a porous structure and a large specific surface ensuring high activity.

Graphical abstract

Keywords

Ammonium sulfate residue; Particulate solids; Active CaO; Suspension decomposition; High solid/gas ratio