Condensing phenomenon of moisture in sintering bed and its effect on sintering process were quantitatively studied through a mathematical model and experiments with sintering pot. The results obtained are as follows:
(1) Remarkable reduction of bed permeability after ignition is mainly due to formation of moisture condensation zone in bed. Resistance to gas permeation in moisture condensation zone is higher than that in initial raw mixture zone.
(2) The amount of condensed moisture is determined by the difference between wet-bulb temperature of gas passing through the bed and temperature of raw mixture. The less the difference is, the less the amount of condensed moisture is.
(3) As the amount of condensed moisture reaches a critical level at which sticking force of fine grains in quasi-particles starts to decrease, quasi-particles begin to agglomerate. Thus voidage of bed decreases and resistance to gas permeation increases sharply.
(4) It is proposed that effective means for suppressing moisture condensation after ignition are increase of raw mixture temperature, reduction of humidity in gas passing through bed, addition of moisture-absorber to bed and granulation of raw mixture at lower moisture content, etc.
