Recovery of CaO by Reductive Decomposition of Spent Gypsum in a CO-CO 2-N2 Atmosphere

Satoshi Okumura, Naoto Mihara, Ken Kamiya, Shoji Ozawa, Maurice S. Onyango, Yoshihiro Kojima, Hitoki Matsuda, Kyaw Kyaw, Yoshimi Goto, Tetsushi Iwashita

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37 Citations (Scopus)


Reductive decomposition of spent CaSO4 was studied using a packed-bed reactor to regenerate an alternative CaO sorbent. The reactor was operated at various process conditions including an increasing CO concentration, CO/CO2 concentration ratio (0.067-1), and temperature (1123-1273 K). In all cases, N2 was used as a balancing gas. The regeneration of CaO from CASO4 was found to be most effective in the CO-CO 2-N2 atmosphere and strongly depended on the CO/ CO 2 concentration ratio. At 1273 K, an apparent conversion value of 0.91 for the decomposition of CASO4 to CaO was obtained in a 2 vol % CO and 30 vol % CO2 atmosphere. On the other hand, in a CO-N 2 atmosphere, CaS was predominantly produced. The SO2 absorption capacity of CaO regenerated from CASO4 was higher than that of limestone-calcined CaO. A larger pore diameter of the regenerated CaO was considered to be responsible for the higher SO2 absorptivity.

Original languageEnglish
Pages (from-to)6046-6052
Number of pages7
JournalIndustrial and Engineering Chemistry Research
Issue number24
Publication statusPublished - 26-11-2003

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • General Chemical Engineering
  • Industrial and Manufacturing Engineering


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