Gas composition, temperature and pressure measurements in a lead blast furnace
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T HE i n d u s t r i a l w i n n i n g of lead f r o m mixed sulfide o r e i n v o l v e s the following steps: 1) The c r u s h e d ore is t r e a t e d in flotation c e l l s to achieve a p a r t i a l s e p a r a t i o n of lead s u l f i d e . 2) The lead sulfide c o n c e n t r a t e , mixed with l i m e , s i l i c a sand, and r e c y c l e s i n t e r , is oxidized with a i r to f o r m the lead oxide s i n t e r . 3) The c r u s h e d s i n t e r is c h a r g e d with coke to a b l a s t f u r n a c e w h e r e i n the s i n t e r is r e d u c e d by the a s c e n d i n g g a s e s to m e t a l l i c lead b u l l i o n . 4) The m o l t e n lead b u l l i o n is r e f i n e d to p u r i f y the lead and r e c o v e r d i s s o l v e d m e t a l s . A m a j o r e n e r g y r e q u i r e m e n t of the o v e r a l l p r o c e s s is r e p r e s e n t e d by the coke feed to the b l a s t f u r n a c e . At the lead b l a s t f u r n a c e of B r u n s w i c k M i n i n g and S m e l t i n g Ltd., B e l l e d u n e , N.B., Canada, the coke to s i n f e r r a t i o is t y p i c a l l y 0.18 to 0.20 on a weight b a s i s ; m u c h g r e a t e r than the r a t i o 0.10 to 0.11 r e p o r t e d as t y p i c a l for other furnaces.1 A t t e m p t s to r e d u c e this r a t i o at the B e l l e d u n e f u r n a c e have r e s u l t e d in " f r e e z i n g " of the f u r n a c e , i.e. s o l i d i f i c a t i o n at v a r i ous points in the f u r n a c e of the b u r d e n . In o r d e r to d i a g n o s e the p r o b l e m , m e a s u r e m e n t s of the t e m p e r a t u r e , gas c o m p o s i t i o n and p r e s s u r e w e r e made at v a r i o u s depths within the f u r n a c e . P r e l i m i n a r y m e a s u r e m e n t s were made by Ho, K a r m a n and Lee; 2 this p a p e r r e p o r t s the m e a s u r e m e n t s by Chao 3 and offers an i n t e r p r e t a t i o n . THEORY The m a j o r r e d u c i b l e c o n s t i t u e n t s of the s i n t e r feed to the b l a s t f u r n a c e a r e the oxides or s i l i c a t e s of lead, i r o n and z i n c . P o s s i b l e r e d u c t i o n r e a c t i o n s by the a s c e n d i n g c a r b o n monoxide gas a r e : PbO + C O = P b + C O 2 3Fe203 + CO = 2Fe304 + CO2
[1] I2]
Fe304 + CO = 3FeO + CO2
[3]
FeO+CO=
Fe+CO2
ZnO+CO=
Zn+CO2
[4] [5]
M2SiO4 + 2CO = 2M + SiO2 + 2CO2
[6]
JOHN T. CHAO is Graduate Student, DAVID R. MORRIS is Professor, and FRANK R. STEWARDis Professor and Chairman, all with the Department of Chemical Engineering,University of New Brunswich, Fredericton, N.B., Canada E3B 5A3. PETER J. DUGDALE is Technical Superintendent, BrunswickMining and Smelting Co., Belledune, N.B., Canada E0B 1G0. Manuscript submitted November 2, 1977. METALLURGICALTRANSACTIONS B
w h e r e M =- Pb, Fe(II) or Zn. T y p i c a l a n a l y s e s of the s i n t e r , s l a g and b u l l i o n a r e given in T a b l e I; the i r o n content of the s i n t e r is r e l a t i v e l y high. 1 T h e r m o d y n a m i c and s t o i c h i o m e t r i c c a l c u l a t i
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