Permeability measurement of individual iron ore pellet
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Permeability Measurement of Individual Iron Ore Pellet S. B. SARKAR T h e b u r d e n p e r m e a b i l i t y in i r o n m a k i n g has d r aw n much a t t e n t i o n of r e s e a r c h w o r k e r s and d e s i g n e r s in r e c e n t y e a r s . P e r m e a b i l i t y of the p e l l e t i t s e l f is a l s o i m p o r t a n t b e c a u s e it d e t e r m i n e s flow of g a s e s t h r o u g h a p e l l e t or o r e p a r t i c l e d u r i n g r e d u c t i o n . An idea about the a m o u n t of p o r e s of a p e l l e t can be obtained ind i r e c t l y by the a p p a r e n t d e n s i t y m e a s u r e m e n t s . P o r o s i m e t e r m e a s u r e m e n t s on the o t h e r hand would indicate the a m o u n t of open p o r e s in the p e l l e t o r i r o n o r e particle. Permeability of a pellet represents that fraction of the open pores that are interconnected and continuous. The pores act as passages for the transport of reducing gas and product of reduction. Hence permeability measurements can be utilized in understanding reduction characteristics of iron ore pellets. The author has successfully used a sand permeability meter, with little modification, for measuring permeability of an iron ore pellet. The apparatus consists of a sand permeability meter used in sand laboratory, with a special type of specimen holder for iron ore pellets (Fig. 1). Cylindrical specimens of 1 cm diam and 1.5 cm height, as shown S. B. SARKAR is Lecturer, Metallurgical Engineering Department, Indian Institute of Technology, Kharagpur 721302, India. Manuscript submitted June 17, 1976.
316-VOLUME 9B, JUNE 1978
2000 I. AtR
DRUM
2. CUP FOR
FILLPNG
MANOMETER
3, WATER S E A L 4- MANOMETER
5. P E L L E T , b' S P E C I M E N
HOLDER
7' N O Z Z L E e. MERCURY
SEAL
i
____-__
Fig. 1--Set up for measuring permeability of iron ore pellet.
Table I. Permeability and Apparent Density of Noamundi (India) Iron Ore Pellets Containing Various Amounts of CaO and Bentonite and Fired at 1100~
Pellet
Permeability
Apparent Density g/cc
A
16 20 21 15 12
3.50 3.17 3.23 3.42 3.89
B
C D E
in F i g . 1, w e r e m a d e out of i r o n o r e p e l l e t s by g r i n d ing t h o se on e m e r y p a p e r . T h e top and b o t t o m s u r f a c e s of the p e l l e t w e r e left untouched b e c a u s e g r i n d ing of t h e s e s u r f a c e s might c a u s e chocking of the fine p o r e s . Th e s p e c i m e n was then pushed inside the s p e c i m e n h o l d e r and the p e r i p h e r y of the s p e c i m e n was s e a l e d off by a c h e m i c a l a d h e s i v e . Th e p e r m e a b i l i t y of the p e l l e t was then c a l c u l a t e d f r o m the following f o r m u l a : VH
Permeability - pAt
[11
where, V = 2000 cu c m of a i r p a s s i n g t h r o u g h the s p e c i m en H = Height of the s p e c i m e n p = P r e s s u r e = 10 g / c m z A = C r o s s s e c t i o n a l a r e a of the s p e c i m e n t = T i m e , s, f o r 2000 cu c m a i r to p a s s through the s p e c i m e n . T h e table g i v e s p e r
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