Yb. Hahn et Ks. Chang, MATHEMATICAL-MODELING OF THE REDUCTION PROCESS OF IRON-ORE PARTICLES IN 2 STAGES OF TWIN-FLUIDIZED BEDS CONNECTED IN SERIES, Metallurgical and materials transactions. A, Physical metallurgy andmaterials science, 29(5), 1998, pp. 1107-1115
Citations number
19
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science","Metallurgy & Metallurigical Engineering
A mathematical model is presented to describe the reduction process of
iron ore particles in two stages of twin-fluidized beds (TFBs) connec
ted in series: prereduction and final reduction stages. Main features
of the model are the inclusion of particle degradation phenomenon to a
ccount for its effect on reduction of iron oxides and reduction kineti
cs for multiparticles having a wide size distribution. It was found th
at about 90 pct of overall particle degradation occurs in the prereduc
tion stage mainly due to thermal stress and volume expansion. The redu
ction degree of particles larger than 1 mm decreased fast with increas
ing particle size in both the prereduction and final reduction stages.
However, the particles sized between 0.2 and 1 mm showed mild increas
e in reduction degree, and steep increase for the fines smaller than 0
.2 mm. The reduction degree was also gradually decreased with increasi
ng the gas oxidation degree of feed gas in both the prereduction and f
inal reduction stages. It was found that to obtain a desired reduction
degree, it is of great importance to control the bed temperature in s
tage I rather than in stage II. The optimum range of residence time wa
s 15 to 20 minutes in the prereduction stage and 30 to 35 minutes in t
he final reduction stage.