Kinetics of oxidation of CaS particles in the regime of low SO2 release

Citation
G. Marban et al., Kinetics of oxidation of CaS particles in the regime of low SO2 release, CHEM ENG SC, 54(1), 1999, pp. 77-90
Citations number
41
Categorie Soggetti
Chemical Engineering
Journal title
CHEMICAL ENGINEERING SCIENCE
ISSN journal
00092509 → ACNP
Volume
54
Issue
1
Year of publication
1999
Pages
77 - 90
Database
ISI
SICI code
0009-2509(199901)54:1<77:KOOOCP>2.0.ZU;2-8
Abstract
The influence of temperature and oxygen partial pressure on the oxidation o f pure CaS particles (empty set = 18.6 mu m) in the regime of low SO2 relea se (T < 890 degrees C for p(O2,O) = 0.21 atm, or T < 840 degrees C at any o xygen partial pressure) has been studied by means of thermogravimetric anal ysis. The kinetics of the process was analysed with the unreacted core mode l. After a short period of chemical control, the process is governed by sol id-state diffusion through the product layer. The effective diffusivity of oxygen in the CaSO4 lattice decreases with conversion and is a function of temperature and oxygen partial pressure. This dependence can be explained b y a grain boundary diffusion mechanism. This is thought to proceed via migr ation of Ca2+ and S2- ions from the CaS/CaSO4 interface to the particle sur face, where the ions are oxidised to CaSO4 by gaseous oxygen. (C) 1998 Else vier Science Ltd. All rights reserved.