SECTION VI LEAD SMELTING AND REFINING
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SECTION VI
LEAD SMELTING AND REFINING
Chapter 24
THE HERZUWNEUM L'L443 SKELT3R OF
ST. JOE XINEFUiLS CORPORATION Herculaneum, Missouri
Donald H. B e i l s t e i n Chief M e t a l l u r g i s t , Lead Smelting Divis ion
Abs t rac t
The S t . Joe Minerals Sorpora t ion Lead Smel ter and f ief inery have been i n continuous opera t ion a t Herculaneum, IvIissouri s i n c e 1892 a s t h e Herculaneum Lead Smelting Divis ion. Over t h e y e a r s , t n e p l a n t has undergone aany c h a n ~ e s t o i n c r e a s e production, improve t h e technology, reduce t h e c o s t of opera t ions , and produce t n e h i g h e s t grade o f primary l ead .
The l a t e s t a l t e r a t i o n s were beiun i n 1950 and completed i n 1970 and have r e s u l t e d i n t h e ~ H e r c u l a n e h Smel ter ca?acitjl being in- creased t o i n excess of 203,003' tons per y e a r (190,300 met r i c tons ) . This i n c r e a s e has made t h e Herculaneum Smel ter t h e l a r g e s t i n t h e United S t a t e s , and second i a r g e s t i n t h e world.
This Taper w i l i d e s c r i b e tine %erculaneum Smel ter equipment, prozesses , and m a t e r i a l baiances. P a r t i c u l a r emphasis w i l l be given t o t'1e I*:c2owell-;.JelLnan i O t x 100' ( 3 x 30 n e t e r ) up-draft s i n t e r machine a d z n c i l l a r i e s ; t 3 tlne new Heavy Smelting 3eparhnect ( b l a s t f u r i x c e s 2nd d ross ing s e c t i o n ) ; t o t h e new Lead Iiefinery and i t s automatic c a s t i n g equipnent .and t o t h e gas handling system inc lud ing t h e 340 tons ?e r day (305 met r i c ) S u i f a r i c Acid ? l a n t u t i l i z i n g a f o u r pass conver ter .
The d o s c r i p t i o n ,dl1 i n c l u d e ?hotogra?hs, fio:i s h e e t s , tonnages and assays where a p p l i c a b l e .
Fig
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Lead mining i n t h e Southeast Missouri a r e a d a t e s back t o the e a r l y 1700's. Lead metal product ion followed mining, p r imar i ly a t t h e mine s i t e . . Herculaneum, Missour i , approximately 25 miles (40 km) south of S t . Louis on the west bank of the M i s s i s s i p p i River , was the s i t e of sho t towers i n the e a r l y 1 8 0 0 t s , us ing l ead from the Southeast Missouri mines and smel te r s .
I n 1892, t h e p resen t smel te r was e s t a b l i s h e d and has been i n con- t inuous , expanding opera t ion ever s ince . A s technology has changed, the smel ter has changed - from Calcine fu rnaces , t o Savelsburg con- v e r t e r s , t o small down-draft s i n t e r machines, t o a modern up-draft s i n t e r machine; from 36" diameter (.92 meter) cupolas t o 36" x 100" (. 92 x 2.54 meter) b l a s t fu rnaces , t o modern 66" x 336" (1.68 x 8.53 meter) b l a s t furnaces; from mat te r o a s t e r s t o modern dross ing p r a c t i c e ; from rudimentary r e f i n i n g processes t o p resen t r e f i n i n g p r a c t i c e , r e s u l t i n g i n 99.99+% lead.
The Herculaneum Smelter was p r a c t i c a l l y r e b u i l t , department by department, dur ing t h e 1 9 6 0 t s , wi th much of t h e design and engineer- ing provided by Treadwell Engineering Company, New York. A new m a t e r i a l s handling-receiving s e c t i o n , a new up-draft s i n t e r s e c t i o n , new b l a s t fu rnaces , a new Drossing P l a n t , a new Refinery, a new bag- house, and a new S u l f u r i c Acid P l a n t , were a l l constructed i n t h e decade 1960-1969, r e s u l t i n g i n a designed capac i ty of 200,000 tons (180,000 met r i c ) per yea r . The fol lowing d e s c r i p t i o n s represen t cur ren t i n s t a l l a t i o n s , p r a c t i c e , metal lurgy and opera t ions a t t h e Herculaneum Lead Smelting Divis ion of t h e S t . Joseph Lead Company.
RECEIVING AND MATERIALS HANDLING SECTION
The smel te r i s served by the Missouri P a c i f i c Rai l road, which has a switch yard ad jacen t t o t h e smel ter . A l l m a t e r i a l s a r e re- ceived by r a i l , except f o r minor tonnages of f l u x and miscellaneous mate r ia l s .
An i n t e r n a l r a i l system, wi th 9 miles of t r a c k (14.5 km), se rves the smel te r and r e f i n e r y . Equipment f o r t h e r a i l system c o n s i s t s o f :
1 - 95 t o n (85 met r i c ) d i e s e l - e l e c t r i c locomotive 1 - 25 ton (23 metr ic) diesel-mechanical crane 1 - 30 ton (27 met r i c ) diesel-mechanical crane 1 - 40 ton (36 metr ic) d i e s e l - e l e c t r i c crane 25 - 70 ton (63 met r i c ) s t e e l s ide/bot tom dump hopper c a r s 12 - 70 ton (63 metr ic) gondolas 3 - 50 ton (45 metr ic) f l a t c a r s
The l a t t e r t h r e e types of c a r s a r e used f o r in-plant mate r ia l s . A 150 ton (135 met r i c ) r a i l r o a d s c a l e i s used f o r a l l in-bound, out- bound, and i n t e r n a l t r a n s f e r s . The engine crew c o n s i s t s of t h r e e
St. loe Minerals C
o~
p.
Herculuneum
, Missouri, U
SA
Chapter 24, page 702
Am
x-Hom
estake Lead T
ollers B
zsick, Missouri, U
SA
Chapter 25, page 738
Am
erican Smelting &
Refining C
o. G
louer, Missouri, U
SA
Chapter 26, page 777
Broken Hill A
ssociated Smelters P
ty., Ltd.
Port Pirie, So. A
us., Azsstralin
Chapter 27, page 790
N.V
. Metallurgie H
oboken S.A.
Hoboken, B
elgium
Chapter 28, page 824
Mitsubishi-C
ominco Sm
elting Co.
Naoshim
a, Japan C
hapter 29, page 853
Air P
hotograph by Aero-L
ux, Frankfurt/M
ain R
eleased by Reg. P
raes. Wiesbd. N
r. 70
4/6
7
Norddeutsche A
finerie (N .A
.) H
amburg, F
ederal Republic of
Germ
any C
hupter 30, page 867
Cerro de Pasco C
orp. La O
roya, Peru C
hapter 31, page 891
men. The s e l f - p r o p e l l e d crane crew is made up of an o p e r a t o r p lus h e l p e r .
Concentrates a r e received from the Southeast Missouri l ead mines i n 100 t o n capac i ty (90 met r i c ) gondolas. Weighing and sampling i s performed immediately upon a r r i v a l . Excess r e c e i p t s , a f t e r weigh- i n g and sampling, a r e he ld i n the p l a n t swi tch yard . Two thaw houses a r e i n use - an old b r i c k and wood u n i t wi th a 6-car capac i ty , and a new s t e e l u n i t w i t h a 24-car capac i ty . Loaded c a r s a r e a l s o s t o r e d h e r e f o r p r o t e c t i o n from t h e r a i n i n mild pe r iods . During the w i n t e r months these u n i t s func t ion a s t r u e thaw houses , f i r e d by two 4 x 106 Btu/hr ( 1 x 106 kg-cal /hr) forced a i r furnaces .
A l l gondolas, a f t e r weighing and sampling, a r e taken t o t h e Rota- s i d e c a r t i p p l e r . This u n i t handles one c a r a t a t ime; r o t a t e s the c a r and t r a c k approximately 150°, v i b r a t e s t h e c a r u n t i l empty, and r e t u r n s i t t o t h e down p o s i t i o n . The complete cyc le i s about 6 - 8 minutes , which inc ludes c a r movement and dumping.
Figure 2. Rota-side Car Tippler
The Rota-side c a r t i p p l e r i s a Stephens-Adamson u n i t ( b u i l t t o St rachan & Henshaw Ltd. , U .K . des ign) capable of handl ing a 150 ton (135 met r i c ) g ross weight gondola. It i s powered by a 100HP, 720 r.p.m. motor. Braking i s v i a a D. C. twin magnetic type brake. Limits a r e c o n t r o l l e d by a t r a v e l l i n g nu t type switch. Photo-elec- t r i c eye sa feguards a r e provided t o ensure proper c a r l o c a t i o n .
Mater ia l i s dumped i n t o a four compartment bottom-discharge hop- p e r , where i t i s fed on t o a conveyor b e l t f o r t r a n s f e r t o a t r i p p e r loca ted over the s i n t e r p r e p a r a t i o n (mix room) b i n s . On a normal day, 10 concen t ra te c a r s and 4 - 5 miscel laneous m a t e r i a l c a r s a r e unloaded and de l ive red t o the b ins . A three-man crew, working day s h i f t on ly , opera tes t h e unloading system.
I n a d d i t i o n t o t h e above, b l a s t furnace coke and excess s i n t e r product ion is handled by bottom-dump c a r s t o t h e b l a s t furnace r a i l - road t r e s t l e f o r dumping i n t o t h e t r e s t l e b ins .
SAMPLING SECTION
A new sample room was b u i l t i n 1969 and is equipped wi th t h e fol lowing:
1 - 8" x 10" Denver Jaw c rusher (20 x 25 cm) 2 - i/00 S tu r t evan t automat ic c o a l c r u s h e r s , which a r e
b a s i c a l l y 20 1/2" (52 cm) cone c r u s h e r s , max. feed 3" (7.6 cm)
1 - Bedeck Gyratory c rusher , max. feed 1" (2.5 cm) 3 - Bico-Braun model UA d i s c p u l v e r i z e r s wi th 8"
(20 cm) d i s c s 1 - Massco/McCool p u l v e r i z e r - 9" (23 cm) d i s c s 2 - Michigan Oven Company /I334 d ry ing ovens - 71" x 48" x
93", r a t e d a t 110,000 ~ t u / h r , n a t u r a l gas f i r e d (180 x 120 x 235 em, r a t e d a t 27,500 kg-cal /hr)
Sampling and sample p r e p a r a t i o n i s handled by f i v e men working day s h i f t . I n a d d i t i o n t o incoming and outgoing m a t e r i a l s , a l l t h e s l a g , ma t t e , d r o s s , fume and d u s t , and o t h e r i n t e r n a l miscel laneous m a t e r i a l s a r e sampled f o r assay.
The Yard Department s u p p l i e s a genera l l a b o r poo l , and is respon- s i b l e f o r rubber- t i red t r a n s p o r t a t i o n , change house and laundry f a c i l i t i e s , j a n i t o r i a l s e r v i c e , watchman s e r v i c e , r a i l r o a d t r a c k r e p a i r s , and a garage f o r s e r v i c i n g and l i g h t r e p a i r s .
SINTER PLANT
The new S i n t e r P l a n t a t Herculaneum, which went on s t r eam i n January, 1966, i s of t h e up-draft des ign , r e p l a c i n g f i v e smal le r down-draft machines. Design cons ide ra t ions were t o i n c r e a s e capac- i t y , produce h igh grade SO2 f o r a c i d product ion, produce more s i n - t e r more economically, and improve hygiene cond i t ions . A l l of t h e s e requirements have been met by t h e new i n s t a l l a t i o n .
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C l a w Brlokn D h e ? Col lestton
SINTER PLANT FLOW SHEET
Propor t ioning System and Feed Prepara t ion .
The mix room (propor t ioning system) has 23 concre te , vee-bottom b i n s a s fo l lows:
No.of Bins Contents 5 Granulated b l a s t furnace s l a g
12 Lead concen t ra tes 1 Sand 1 Crushed l imestone 1 Crushed i r o n o r e 1 Secondary m a t e r i a l s ( i n p l a n t ) 2 Baghouse fume and d u s t
Concentrate capac i ty i n these b i n s is 3,000 tons (2,700 m e t r i c ) ; s l a g capac i ty is 850 tons (770 met r i c ) . A l l m a t e r i a l s e n t e r the b i n s v i a an overhead t r a v e l l i n g t r i p p e r conveyor. Below each b i n , an apron feeder con t inua l ly withdraws m a t e r i a l and d i scharges i t onto a c o l l e c t o r conveyor. Manually opera ted , pre-se t g a t e s de te r - mine t h e r a t i o of t h e charge components. The tonnage de l ive red by the p ropor t ion ing system can be va r i ed by means of remote c o n t r o l frequency regu la ted d r i v e motors on t h e apron feeders . The weight of t h e raw feed p r o p o r t i o n a t e l y c o n t r o l s the weight of r e t u r n s in - t e r f e d from a s e p a r a t e 150 ton (135 met r i c ) b i n loca ted wi th in the s i n t e r machine bu i ld ing . A b e l t s c a l e weighs t h e raw feed and e lec - t r o n i c a l l y c o n t r o l s a weigh feeder below t h e r e t u r n s b i n according t o a r a t i o s e t by t h e c o n t r o l room o p e r a t o r . The mixed feed e n t e r s a Gundlach Cage-Paktor where i t i s mixed and crushed t o approximately 85% -114" ( . 6 cm). From the Cage-Paktor, the mixed feed i s moistened
Figure f t . P e l l e t i z i n g Drum
and p a r t i a l l y p e l l e t i z e d i n a 9 ' x 30' (2.75 x 9.15 meter) A l l i s - Chalmers v a r i a b l e speed drum. The p e l l e t i z i n g drum i s f i t t e d wi th a d j u s t a b l e water sp rays and a r e c i p r o c a t i n g c u t t e r ba r .
Machine Feed and S i n t e r i n g .
The mixed f e e d , l eav ing t h e p e l l e t i z i n g drum, is d i r e c t e d by an e l e c t r i c a l l y pos i t ioned f l o p g a t e i n t o one of two divergent chutes . The smal le r p o r t i o n ( l o % ) , con ta in ing somewhat smal l e r p e l l e t s , i s fed onto a h y d r a u l i c a l l y operated r e c i p r o c a t i n g b e l t f eeder which d i scharges i n t o t h e 10' x 2' i g n i t i o n l a y e r hopper ( 3 x .61 meter) . The balance (90%) i s s i m i l a r l y fed i n t o a 10 ' x 4' (3 x 1 . 2 meter) main l a y e r hopper. The i g n i t i o n l a y e r i s c u t o f f and l e v e l l e d by a s t a i n l e s s s t e e l back p l a t e a t approximately 1 1/411 (3.2 cm).
Down-draft i g n i t i o n i s accomplished i n 84 inches (2.13 meter) of t r a v e l through a n a t u r a l gas-f i red muff le , 9 ' x 10' x 4 '(2.75 x 3 x 1 .2 me te r ) , us ing f o u r burners . Af te r i g n i t i o n , the main l a y e r i s l a i d down and l e v e l l e d t o 10" - 14" (25 - 35 cm) by a s t a i n l e s s s t e e l back p l a t e . Up-draft s i n t e r i n g s t a r t s immediately and burn- through is accomplished i n about 30' (9.15 meter) . The remaining 70' (21.4 meter) a r e used t o cool t h e cake wi th up-draft a i r .
F igure 5. S i n t e r Machine Hood and Off-takes
S i n t e r gases from t h e f i r s t 30 ' (9 .15 meter) of the s i n t e r machine con ta in ing 6% - 8% SO2 by volume, a r e s e n t t o the Acid P l a n t . The balance of t h e gases go t o the r e g u l a r baghouse.
Crushing and Returns System.
S i n t e r drops o f f t h e p a l l e t s a t the d i scharge end of the machine a s a l a r g e cake, on to a r a i l r o a d r a i l c rash deck. The cake s l i d e s on t o an 8" (20 cm) g r i z z l y , through which i t i s crushed by a claw b r e a k e r , wi th 18" ( . 4 6 meter) claws. A Traylor 42" x 48" (1.0 x 1 .2 meter) toothed r o l l reduces the m a t e r i a l t o -5" (12.7 cm). A Ross Rol l s sc reen i s used t o c o n t r o l t h e amount of r e t u r n s i n t e r . The a p e r t u r e i s remotely c o n t r o l l e d and i s u s u a l l y s e t a t 2". F i n a l s i n t e r , +2" (5 cm); then t r a v e l s by conveyor b e l t t o one of t h r e e s i n t e r s t o r a g e b i n s ( see Lead Blas t Furnace Department). Excess s i n t e r product ion goes t o r a i l r o a d c a r s f o r d i scharge on the b l a s t furnace charge b i n t r e s t l e , o r yard s to rage .
Figure 6 . S i n t e r Machine Operating Floor
Return s i n t e r , -2" (5 cm), which was separa ted by t h e Ross R o l l s , i s conveyed t o a 7 ' x 20' (2.14 x 6.1 meter) L o u i s v i l l e coo l ing drum. Thickened scrubber s ludge i s used t o coo l t h e r e t u r n s i n t e r . The cooled r e t u r n s a r e f u r t h e r crushed t o -112" (1.2 cm) by a Traylor 42" x 36" (1.0 x .92 meter) smooth r o l l be fo re being conveyed t o t h e 150 ton (135 met r i c ) r e t u r n s i n t e r b in . Rota t ing paddles i n t h e b i n i n d i c a t e b i n l e v e l t o the opera to r i n t h e c o n t r o l room, and guide h i s s e t t i n g of t h e Ross R o l l s opening.
Typical Operating Data.
Chemical Analys is
Mate r i a l Lead % S u l f u r % New feed 40-45 9-13 Returns 43-45 1.2-1.7 Machine feed 40-45 4.7-7.0 F in i sh S i n t e r 45-50 1.0-1.5
Typical F i n i s h S i n t e r Analys is - %
CaO S Pb Cu I n s o l a FeO - - - - .- 4 8 1 10 9 15 5 1 .4
S i z i n g
Mate r i a l +1" (2.5 cm) +3/4'; (1.9 cm) +.37 (.94 cm) +3 mesh +6 mesh +14 mesh +35 mesh -35 mesh
% Returns 3
% Machine Feed - 3 4 7 15 20 30 21
Typical ly the S i n t e r P l a n t Operates wi th :
New feed 50% Returns 50% Machine feed 100%
Machine Operat ing l ia ta
P a l l e t speed 45-55"Imin (114-140 cmlmin) I g n i t i o n bed depth 1 114" + 118" (3.2 cm + . 3 cm) To ta l bed depth 10-14" (25-35 cm) Down-draf t a r e a 70 s q . f t . (6.5 sq.meter)
( inc lud ing dead-plate) Up-draf t a r e a 1040 s q . f t . (96.7 sq.meter)
( inc lud ing dead-pla te) No. of up-draft windboxes 1 3 To ta l number of p a l l e t s 104
Operat ing Tonnages
Tons Per Hour (me t r i c ) To ta l machine feed 160 - 180 (145 - 160) F in i sh S i n t e r 75 - 100 (68 - 90)
Windbox No. 1 2 3 4 5 6 7 8 9
10 11 12 1 3
Down- d r a f t
To ta l
Air D i s t r i b u t i o n
Volume 8000 cfm (226 cu meter) 8500 " (240 " ) 9000 " (254 " ) 15000 " (425 " ) 15000 " (425 " ) 15000 " (425 " ) 15000 " (425 " ) 7000 I' (200 ) 7000 I' (200 " )
Not i n use a t p r e s e n t 11
I I
I I
7200 cfm (204 cu meter) 106,700 " (3024 " )
Pressure - 15 20 20 2 0 15 10 1 0
5 5
Inches Water Gauge
(38 cm) (51 " ) (51 " ) (51 I' ) (38 " ) (25 " ) (25 " ) (12 l1 ) (12 " )
-2 t o -3 (-5 t o -7 cm)
Fuel Requirements
Natural gas ( i g n i t i o n ) 85,000 Btu/ton f i n i s h e d s i n t e r (19,400 kg-cal lmetr ic ton)
Labor Requirements
The S i n t e r P l a n t o p e r a t e s wi th s i x men and one foreman on each s h i f t . I n a d d i t i o n , t h e r e a r e t e n men i n the maintenance crew who
work day s h i f t , f i v e days a week. Maintenance i s performed, on sched- u l e , f o r e i g h t hours each Monday and Wednesday. Add i t iona l mainten- ance personnel a r e a v a i l a b l e , a s needed, from t h e main shops. Minor s p a r e p a r t s , such a s vee b e l t s , p u l l e y s , i d l e r s , e t c . , a r e kep t with- i n t h e S i n t e r P l a n t , wh i l e l a r g e r p a r t s a r e k e p t i n c e n t r a l s t o r e s .
Ins t rumen ta t ion .
The S i n t e r P l a n t c o n t r o l room h a s many ins t rumen t s and t h e i n f o r - mation provided by them has been a major f a c t o r i n r each ing t h e p r e s e n t h igh l e v e l of ope ra t ion . The c o n t r o l room conso le c o n t a i n s :
Mix room b i n s t a r v a t i o n alarms and r e c o r d e r s , w i th l o c a l alarms i n t h e mix room.
Feed r a t e i n d i c a t o r s and t o t a l i s e r s f o r new f e e d , r e t u r n s and f i n i s h s i n t e r .
Returns r a t i o c o n t r o l l e r . Air volume c o n t r o l l e r s and recorde r s on each
windbox and blower. Windbox p r e s s u r e r e c o r d e r s , w i t h a c o n t r o l l e r
only on t h e down-draft windbox. Temperature c o n t r o l l e r s on a c i d and exhaust
gases which o p e r a t e water sp rays v i a s t ep -con t ro l l ed so leno id v a l v e s .
Miscel laneous temperature r e c o r d e r s . Ross R o l l s a p e r t u r e c o n t r o l l e r . Level moni tors on t h e r e t u r n s b i n and a h igh
l e v e l monitor on t h e f i n i s h s i n t e r b i n . Water volume r e c o r d e r and p r e s s u r e i n d i c a t o r
f o r t h e machine hood sprays . Cooling and p rocess water c o n t r o l l e r s . E l e c t r i c a l i n t e r l o c k s , ammeters, speed
c o n t r o l l e r s and o t h e r e l e c t r i c a l moni tors throughout t h e p l a n t .
Continuous r ecorde r f o r SO2, 02, and N2 i n Acid P l a n t gas v i a an L & N chromatograph.
Various p r e s s u r e and temperature alarms.
Dust Control .
Every e f f o r t has been made t o minimize t h e contaminat ion of t h e a r e a by d u s t . A l l t r a n s f e r p o i n t s and major d u s t producers a r e hooded and vented t o an e l a b o r a t e scrubbing system. There a r e s i x wet s c r u b b e r s , w i th a t o t a l c a p a c i t y o f 185,400 cfm (5,250 cu meter / min). T o t a l i n s t a l l e d horsepower f o r t h e s e u n i t s i s approximately 650. Scrubber e f f l u e n t i s th ickened i n a 20' (6 .1 meter) Denver t h i c k e n e r . Thickened s ludge is pumped t o t h e r e t u r n s coo l ing drum, and overflow water i s r e t u r n e d t o t h e sc rubber s .
Genera l Equipment Data.
Conveyor B e l t s . A l l conveyor b e l t s a r e 30" ( .76 me te r ) w ide , ex- c e p t t h e c o l l e c t o r b e l t i n t h e mix room which i s 24" ( . 6 1 m e t e r ) , and t h e b e l t s between t h e r e and t h e machine, which a r e 36" ( .92 me te r ) . B e l t s p e e d s a r e u s u a l l y 150' p e r minute (46 m e t e r ) , u s i n g Fa lk r e d u c e r s . Conveyor b e l t i n g is g e n e r a l l y 4 p l y , 1 /4" t o p ( . 6 3 cm) and 1 /16" bottom ( . I 6 cm).
Weighers. A l l we ighe r s a r e "ABC" by McDowell-Wellman.
Feeders . Feede r s i n s i n t e r p r e p a r a t i o n a r e a l l 3 ' x 5 ' ( .92 x 1 . 5 me te r ) ap ron f e e d e r s .
S i n t e r Machine. The s i n t e r machine i s a Dwight-Lloyd type sup- p l i e d by t h e McDowell-Wellman Eng inee r ing Company. The machine p a l l e t s a r e 10 ' wide ( 3 m e t e r ) , and up -d ra f t l e n g t h is 100' (30 me te r ) . The machine s t r u c t u r e i s independent of t h e b u i l d i n g .
There a r e t h i r t e e n up -d ra f t windboxes - twelve 10 ' x 8 ' ( 3 x 2.4 m e t e r ) , and one 10 ' x 6 ' ( 3 x 1 . 8 1 me te r ) . (The down-draft windbox, i n t h e i g n i t i o n s e c t i o n , h a s a 10 ' x 4 ' [ 3 x 1 .2 me te r ] open ing . ) Access doo r s f o r p e r i o d i c c l e a n o u t a r e provided i n each windbox. The down-draft windbox and t h e d i s c h a r g e end of t h e machine have a screw conveyor f o r s p i l l a g e removal.
P a l l e t s a r e d u c t i l e i r o n , and t h e g r a t e b a r s a r e m a l l e a b l e c a s t i r o n . The p a l l e t wheels a r e s o a r r anged t h a t f r o n t and r e a r wheels d e s c r i b e s e p a r a t e a r c s a t t h e end c u r v e s , r e s u l t i n g i n a " r o l l " a c t i o n a t p a l l e t - t o - p a l l e t c o n t a c t , r a t h e r t h a n s l i d i n g a c t i o n , which minimizes wear . A s l i d i n g s e a l is provided by wear p l a t e s on t h e machine r a i l s and t h e u n d e r s i d e of t h e p a l l e t s . These r e p l a c e - a b l e p l a t e s a r e l u b r i c a t e d a u t o m a t i c a l l y by h i g h t e m p e r a t u r e , h i g h p r e s s u r e g r e a s e .
There i s a g ' ( 2 . 7 5 me te r ) dead p l a t e p rov ided between i g n i t i o n and up -d ra f t s e c t i o n s ; an 18" dead p l a t e ( .46 me te r ) between each up -d ra f t windbox; and a 6 ' dead p l a t e (1 .8 me te r ) a t t h e end of t h e machine. A l l a r e 314" t h i c k (1 .9 cm).
A g r a t e b a r l e v e l l e r i s i n s t a l l e d i n f r o n t of t h e i g n i t i o n hop- p e r , a s w e l l a s a l i f t e d g r a t e b a r alarm. On t h e u n d e r s i d e of t h e r e t u r n s t r a n d t h e r e i s a g r a t e b a r r a p p e r t o c l e a n t h e g r a t e s . A p a l l e t r e t a r d e r , on t h e r e t u r n s t r a n d , e l i m i n a t e s p a l l e t gap a t t h e d i s c h a r g e end.
Machine speed i s con t inuous ly v a r i a b l e between 20" and 80" p e r minute (50 - 200 cm/min) by a f requency r e g u l a t e d d r i v e .
A c o l l e c t i n g hopper and conveyor b e l t r uns t h e l e n g t h of t h e machine, below t h e r e t u r n s t r a n d , t o c o l l e c t any s p i l l a g e and
de l i ve r i t t o t he r e tu rn s c i r c u i t .
LEAD BLAST FURNACE DEPARTMENT
The Blast Furnaces and Blast Furnace Operations a t Herculaneum a r e c l a s s i c a l examples of lead smelting prac t ice . The copper, an t i - mony, and a r s en i c contents a r e low and do no t produce furnace matte o r spe i s s . The z inc content is s u f f i c i e n t t o make a normal zinc- bear ing s l a g , bu t not so high as t o requ i re any spec i a l considerat ion.
Storage System.
The main s to rage system fo r s i n t e r and coke i s i n b ins below the high l i n e r a i l r oad t r e s t l e . I n add i t ion , these b ins s t o r e f luxes and secondaries. Storage capaci ty is 1600 tons of s i n t e r (1400 met r ic ) , 350 tons of coke (310 met r ic ) , and 500 tons of miscellaneous mater- i a l s (450 metr ic) .
Each b in is constructed of concrete with a steel vee bottom lead- i n g . i n t o a rec iproca t ing p l a t e feeder. These p l a t e feeders a r e hy- d r a u l i c a l l y operated, ind iv idua l ly o r i n p a i r s , by four hydraul ic power un i t s . The rec iproca t ing ac t ion i s cont ro l led by a p i l o t valve actuated by the t r a v e l of the feeder pan. A l l reciprocat ing feeders discharge on t o the main co l l e c to r conveyor b e l t . Only one type of mate r ia l i s fed a t any time.
Addit ional ly , there is l i v e s i n t e r s to rage i n the s i n t e r p l a n t , cons i s t ing of th ree s t e e l b ins with s t e e l vee bottoms. Each has a capaci ty of 350 tons (310 metr ic) . These b ins discharge, by v i - b ra t ing feeders , t o a c ross conveyor b e l t which empties onto the main co l l e c to r b e l t .
Charge System.
The charge system has t h r ee b ins which contain, respec t ive ly , 150 tons of s i n t e r (135metr ic1, 30 tons of coke (27 met r ic ) , and 30 tons of gravel o r secondary mater ia l (27 metr ic) . These b ins a r e fed from the top by a s h u t t l e b e l t which receives mate r ia l from an ex- tension of the main co l l e c to r b e l t . The s h u t t l e b e l t , i n one posi- t i o n , feeds t he coke b in , and, i n another pos i t ion , can feed e i t h e r the s i n t e r o r gravel b in using a f lop gate . The th ree b ins a r e f i l l e d i n t e rmi t t en t l y a s needed.
Below the coke b i n is a v ib r a t i ng feeder , discharging onto, and cont ro l led by, a b e l t weigher. When the pre-determined weight of coke has been de l ivered , the v ib r a t i ng feeder s tops. The mater ia l is de l ivered , by conveyor b e l t s and a t r a v e l l i n g t r i p p e r , t o the proper s i d e of whichever furnace has been designated. Upon a r r i v a l
Fig
ure
8
. B
las
t Fu
rna
ce
F
low
S
heet
a t t h e fu rnace , t h e charge i s d e l i v e r e d t o a s h u t t l e conveyor which t r a v e l s back and f o r t h over t h e l e n g t h of t h e furnace d i s t r i b u t i n g t h e charge i n a minimum of t h r e e passes . I n l i k e manner, s i n t e r is a l s o f ed t o t h e furnace . The charge man i n i t i a t e s t h e complete c y c l e by pushing t h e bu t ton . Manual o v e r r i d e f o r s h u t t l e t r a v e l is pro- vided t o c a t e r f o r charge d i s t r i b u t i o n and i r r e g u l a r charge descent . Charge make-up is determined and s e t i n t h e system c o n t r o l c a b i n e t by supe rv i s ion .
B l a s t Furnace.
The p r e s e n t p l a n t c o n s i s t s of t h r e e b l a s t fu rnaces , two of which a r e u s u a l l y i n ope ra t ion . No two fu rnaces a r e a l i k e i n dimensions o r c o n s t r u c t i o n , r e f l e c t i n g a c o n t i n u a l program t o develop t h e most e f f i c i e n t des ign. A l l fu rnaces a r e of the "Aust ra l ian" type w i t h two rows of tuye res . Dimension d e t a i l s a r e a s i n Table I.
A l l f u rnaces have 6'' t h i c k (15 cm) wa te r cooled s t e e l (thermo- s iphon) j a c k e t s w i t h i n 5' (1.52 meter) of t h e charge f l o o r . Above t h e j a c k e t s , t h e fu rnaces a r e f i r e c l a y b r i c k , 1 3 1 /2" t h i c k (. 34 meter) . The o f f - t ake from each fu rnace i s of t h e thimble type and i s wa te r cooled. It d i scha rges c e n t r a l l y t o a c i r c u l a r s t e e l gooseneck, 72'' i n d iameter (1.83 m e t e r ) , which connects t o t h e main f l u e system.
Each fu rnace ope ra te s wi th a cont inuous s l a g t a p p e r , t h e o u t l e t of which flows i n t o a 9 ' x 3'6" x 3' (2.75 x 1.07 x . 9 1 meter) gas - f i r ed s e t t l e r l i n e d wi th f i r e b r i c k . Molten s l a g overf lows t h e s e t t l e r i n t o a g r a n u l a t i n g system. Furnace b u l l i o n l e a v e s t h e s e t t l e r , v i a a l eadwel l , i n t o a 10 t o n (9 m e t r i c ) r e f r a c t o r y - l i n e d t r a n s f e r l a d l e on a wheeled motorized c a r r i a g e . The l eadwel l is served by a "Y" t r a c k , w i t h one l a d l e and c a r r i a g e i n p l a c e and a s p a r e s i t t i n g on one arm of t h e "Y". The l a d l e s a r e moved t o t h e d ross ing s e c t i o n by one of two 20 t o n (18 m e t r i c ) P & H overhead cranes .
Some t y p i c a l ana lyses a r e a s fo l lows :
COMPONENTS Pb Cu I n s o l Si02 FeO CaO S MgO
V o l a t i l e Ash Fixed Carbon
SINTER 4 8
COKE - -
BLAST FURNACE DIMENSION DETAILS
C r u c i b l e Dep th
Width a t t o p t u y e r e s
Width a t b o t t o m t u y e r e s
Length
H e i g h t
Number o f t u y e r e s
Diamete r o f t u y e r e s
Area a t b o t t o m t u y e r e s
F u r n a c e 1 18" (. 46 m e t e r )
10'6" (3.20 m e t e r )
66" (1.67 m e t e r )
28'1" (8.55 m e t e r )
18' 3" (5.5 m e t e r )
44
4 3/4" ( . I2 m e t e r )
1 5 5 ~ ' (14.4O m e t e r )
F u r n a c e 2 24" ( . 6 l m e t e r )
10'6" (3.20 m e t e r )
66" (1.67 m e t e r )
24'2" (7.30 m e t e r )
16'9" (5.10 m e t e r )
3 8
4 3/4" ( . I 2 m e t e r )
133O' (12.4O m e t e r )
TABLE I
F u r n a c e 3 24" ( .61 m e t e r )
10'6" (3.20 m e t e r )
66" (1.67 m e t e r )
28'1" (8.55 m e t e r )
15 ' 3" (4.65 m e t e r ) 52
3 4 3/4" ( . I2 m e t e r ) w
155O' (14.4- m e t e r ) 5 2 L- r zn 0
% F e * 3
Typical furnace opera t ing d a t a a r e shown below:
Tons s i n t e r smelted124 hours
S ize of charge, s i n t e r , tons
% coke on charge Air volume cfm Air b l a s t oz (kg p e r
sq . cm) Tons s i n t e r / s q . f t / d a y (Metric tons l sq .
meterlday) Tons s in te r /1000 cfm (Metric tons1100 M3/day) S i n t e r s i z e
Coke s i z e
Furnace 1 900 (803 met r i c )
10 (9 met r i c )
9.0 10,500 (298 M ~ ) 35 ( . I54 met r i c )
5 .8 (55.7 met r i c )
90 (28.4 met r i c ) +2" -5"
(+5 -12.7 cm) +1" -4"
(+2.5 -10.0 cm)
Furnace 2 850 (770 met r i c )
10 (9 met r i c )
9.0 9,000 (255 M3) 45 ( . I98 met r i c )
7.2 (68.0 met r i c )
9 5 (30 met r i c )
Air b l a s t i s supp l ied by t h r e e Rootes Connersvi l le c e n t r i f u g a l blowers, each r a t e d a t 15,000 cfm (425 cu meter) @ 63 ozlsq. i n . (. 277 kglsq. cm) , and d r iven by a 350HF' motor. They a r e in tercon- nected by a manifold and va lve system. For t h e upper row of tuyeres , a i r i s supp l ied by Allis-Chalmers c e n t r i f u g a l blowers r a t e d a t 6,000 cfm (170 cu meter) @ 48 oz l sq . i n . (.210 kglsq. cm) d r iven by a lOOHP motor.
Slag Handling System.
Since t h e s l a g handl ing system a t t h e Herculaneum Smelter evolved i n s e v e r a l s t a g e s , i t i s somewhat unusual. A d e t a i l e d d e s c r i p t i o n follows.
Each furnace has i ts own c y l i n d r i c a l g ranu la t ing tank wi th a cone bottom. A toothed d i s c type crusher-feeder , mounted h o r i z o n t a l l y opera tes wi th in the cone bottom, discharging v e r t i c a l l y downward i n t o a h o r i z o n t a l l i n e , j u s t upstream from a v e n t u r i . Overflow s e t t l e r s l a g , which has been granulated by water (1,000 gpm a t 60 p s i g ; 3750 l i t r e / m i n a t 4.2 kg/sq. cm), f a l l s i n t o t h i s crusher i n t h e cone bottom.
S lu ic ing water a t 880 gpm and 275 p s i g (3300 l i t r e / m i n and 19.3 kglsq. cm) flows through t h i s h o r i z o n t a l l i n e and v e n t u r i , p ick ing up t h e g ranu la ted and crushed s l a g . This t h i n s l u r r y is c a r r i e d by abras ion r e s i s t a n t p ip ing t o one of two e leva ted dewatering b ins .
In normal opera t ion , t h e s l u r r y flows i n t o t h e dewatering b i n s and s l a g f a l l s t o the bottom. Overflow water r e t u r n s t o t h e concrete
sump of t h e water c i r c u i t (25,000 cu f t . capac i ty o r 707 cu meter) . Adequate b a f f l i n g i n t h i s sump provides water t o each of t h e t h r e e s l u i c i n g wa te r pumps. Overflow water from t h i s sump a l s o s u p p l i e s t h e g ranu la t ing water pumps.
When a s u f f i c i e n t amount of s l a g b u i l d s up i n the b i n , t h e s l u r r y i s d i r e c t e d t o the o t h e r b i n , and the dewatering cyc le commences. Dewatering i s on a scheduled, automatic cyc le . Numerous screened p o r t s on t h e s i d e s and c o n i c a l bottom of t h e dewatering b i n pass the dra inage water back t o t h e sump when t h e d r a i n va lve i s au tomat ica l ly opened. When d ra ined , a h y d r a u l i c a l l y operated s e a l g a t e a t t h e b i n bottom is opened and t h e dewatered s l a g i s presented t o a r e v e r s i b l e b e l t f eeder . This d i scharges on t o a conveyor system e i t h e r t o t h e S i n t e r P l a n t mix room, o r t o a r a i l r o a d c a r f o r d i s p o s a l on t h e s l a g dump. When the dewatering b i n is empty and ready f o r normal opera- t i o n , the s e a l g a t e and the d r a i n valve a r e c losed ; s l a g s l u r r y flows i n t o i t , and the overflow cyc le begins again . Various p o r t i o n s of t h e c y c l e can be performed manually, i f necessary . The system was supp l i ed by, and is t h e des ign o f , United Conveyor Corporation.
When necessa ry , molten s l a g can b e drawn from t h e s e t t l e r t o wheeled s l a g p o t s , and then hauled t o a dump s i t e by an e l e c t r i c locomotive.
Figure 9. Dewatering Bins
DROSSING SECTION
The d r o s s i n g s e c t i o n c o n s i s t s of f o u r 250 t o n (225 m e t r i c ) capac- i t y hemisphe r i ca l steel k e t t l e s , t h r e e of which a r e used f o r b l a s t fu rnace b u l l i o n , and one of which s e r v e s f o r f i n a l decopper ing of t h e product of t h e f i r s t t h r e e . Dross i s smel ted i n a r e v e r b e r a t o r y fu rnace , 12 ' x 25' (3.65 x 7 . 6 me te r ) , wa te r j acke ted a t t h e s l a g l i n e . The fu rnace a r c h and s i d e w a l l s a r e chrome-magnesite; t h e in - v e r t is s u p e r du ty f i r e c l a y and chrome-magnesite. Two fu rnaces a r e i n s t a l l e d ; on ly one i s i n use a t any t i m e .
A modified soda ash p rocess is used. Bu l l ion is s t i r r e d w i t h soda a s h , s and , and coke u n t i l cooled t o below 950°F (510°C). The d ry d r o s s is removed by a p e r f o r a t e d scoop, u s ing an overhead c rane , and charged d i r e c t l y t o t h e d r o s s r eve rbe ra to ry . The drossed me ta l is then t r a n s f e r r e d , by b a i l i n g i n a 10 t o n (9 m e t r i c ) s teel bucket , t o t h e f o u r t h k e t t l e , where f i n a l decopper ing is done w i t h s u l f u r . This d r o s s i s r e t u r n e d t o one of t h e primary d r o s s i n g k e t t l e s . Oc- c a s i o n a l l y , some r e f i n e r y high-copper p roduc t s from t h e d e s i l v e r i n g o p e r a t i o n a r e a l s o r e t u r n e d t o t h e s e k e t t l e s .
P i g u r e 10. Dross ing K e t t l e s and Reverbera tory i n Background
The d r o s s e s smel ted i n t h e r e v e r b e r a t o r y y i e l d m a t t e , b u l l i o n , and a s m a l l amount of s l a g . Occas iona l ly , a l a y e r of n i cke l -bea r ing m a t e r i a l (which has b u i l t up s lowly a t t h e matte-lead i n t e r f a c e ) is a l s o tapped o u t . The m a t t e , s l a g , and n i c k e l p roduc t s a r e granu- l a t e d , and e i t h e r s o l d o r r e c i r c u l a t e d . Lead meta l i s tapped i n t o
one of the d ross ing k e t t l e s , e i t h e r d i r e c t o r v i a a 12 ton l a d l e (10.7 m e t r i c ) .
Sulfur Droa,
B F Lead B I
DROSSING PLANT FLOW SHEET
Figure 11. Drossing P l a n t
Typical Assays of Dross Sec t ion Feed and Products
Reverb. Copper N i Bul l ion Matte Matte Dross - Lead
% FeO - - - 1.5 -
Some t y p i c a l o p e r a t i n g d a t a a r e shown below:
Weekly Summary of Reverbera tory Opera t ions
M a t e r i a l Charged Dross Soda Ash Coke b reeze S i l i c a sand
M a t e r i a l Tapped Lead b u l l i o n Copper ma t t e S lag N i b e a r i n g m a t e r i a l
Tons (Metr ic) % of Charge 835 (750) 92
Na tu ra l gas is used f o r f u e l . The r e v e r b e r a t o r y fu rnace consumes 500,000 cu f t l d a y (14,150 cu m e t e r ) , and t h e d r o s s i n g k e t t l e s con- sume 90,000 cu f t / d a y (2,550 cu me te r ) .
LEAD REFINERY
The Herculaneum Lead Ref ine ry was r e b u i l t du r ing t h e y e a r s 1960- 1964, i n c o r p o r a t i n g 250 t o n (225 m e t r i c ) k e t t l e s throughout. A l l a r e ar ranged i n l i n e from t h e #1 r e c e i v i n g k e t t l e t o t h e /I11 c a s t i n g k e t t l e . The i n c r e a s e i n k e t t l e c a p a c i t y and t h e number of k e t t l e s has enabled t h e Ref inery t o p rocess i n ' excess of 23,000 tons (21,000
F igure 12. Typ ica l Re f ine ry and Dross P l a n t K e t t l e I n s t a l l a t i o n
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m e t r i c ) of l ead i n a ca l endar month. I n a d d i t i o n t o the " ~ o e Run" and "St. Joe" brands , v a r i o u s a l l o y s a r e produced. A smal l s e p a r a t e a l l o y p l a n t was cons t ruc ted i n 1969 f o r s p e c i a l t y a l l o y s .
A s i l v e r s e c t i o n , us ing r e t o r t s and a cupe l , o p e r a t e s i n t e r m i t - t e n t l y t o produce semi-refined s i l v e r .
Lead me ta l i s c a s t a s 25 l b . (11 kg) plumbers l e a d l i n k s , 100 l b . (45 kg) p i g s , 1,000 l b . (450 kg) i n g o t s , and 2,000 l b . (910 kg) i n g o t s . S i l v e r is produced a s a g ranu la t ed product .
Crane s e r v i c e i n the Refinery i s by two 15 x 3 ton (13.5 x 2.7 me t r i c ) and one 25 x 5 (22 x 4.5 me t r i c ) Shaw Box c ranes , and two 25 x 5 ton (22 x 4.5 m e t r i c ) P & H cranes . A l l c r anes ope ra te on t h e same overhead r a i l s .
F in ished me ta l i s shipped by r a i l , t r u c k , and o c c a s i o n a l l y , by barge on t h e M i s s i s s i p p i River.
Equipment.
K e t t l e s . The k e t t l e s i n the Ref inery a r e cons t ruc ted of grade C f i r e b o x s t e e l (ASTM A-285), 1 114" (3.2 cm) t h i c k . K e t t l e s a r e hemispher ica l w i th a 6 '9" (2.06 meter) r a d i u s , surmounted by a 12" h igh (30.5 cm) c y l i n d r i c a l s e c t i o n , capped wi th a r o l l e d l i p of 5 318" r a d i u s (13.6 cm). Kettles a r e s t r e s s - r e l i e v e d a t 1,600°F (870°C) by the manufacturer.
Each k e t t l e s e t t i n g i s a s t e e l s h e l l , l i n e d wi th 4 112" (11.4 cm) of i n s u l a t i n g b r i c k , w i th another 4 112" (11.4 cm) of f i r e b r i c k on the f i r e f a c e . The bottom of t h e s e t t i n g is formed by a 5" (12.7 cm) tamped l a y e r of mixed asbes tos and cement on top of r e in fo rced concre te . A l a y e r of rammed r e f r a c t o r y , a t l e a s t 5" (12.7 cm) t h i c k , c o n s t i t u t e s the bottom f i r e f ace . The bottom s l o p e s toward a d r a i n ho le . The low p o i n t of t h e k e t t l e i s 30" (76 cm) above t h e r e f r a c - to ry .
Heat is provided by t h r e e Maxon Premix burne r s p e r k e t t l e , set a t 120° , and f i r i n g t a n g e n t i a l l y . Each burner is 24" (61 cm) above t h e bottom and is r a t e d a t 2.6 x l o 6 ~ t u / h r (655 x 103 kg-ca l fh r ) us ing n a t u r a l gas. P rov i s ion i s a l s o made f o r emergency f u e l o i l f i r i n g . Sa fe ty p i l o t l i g h t s and automat ic temperature c o n t r o l s a r e i n s t a l l e d on each k e t t l e .
S t i r r e r s , Pumps, Dezincing and Cast ing Machines. A l l stirrers use f o u r b laded i m p e l l e r s , v e r t i c a l l y mounted on a frame t h a t s i ts on t h e k e t t l e r i m . Power is supp l i ed by a 40HP motor. The impe l l e r is 22" i n d iameter (56 cm) and o p e r a t e s w i t h i n a. 30" d iameter basket - type shroud (76 cm). The b a s k e t i s 34" (86 cm) high and extends upward from t h e lowest p o i n t of t h e impe l l e r .
A l l l e a d pumps a r e c e n t r i f u g a l , w i t h curved i m p e l l e r s . Three s i z e s of i m p e l l e r s a r e i n u se : 6" d i ame te r , 8" d i a m e t e r , and 8 318" d iameter (15 cm, 20 cm, and 21 cm). The p e r i p h e r a l d i s c h a r g e o f t h e i m p e l l e r i s t o 1" o r 1 114" (2 .5 o r 3.2 cm); 2" (5 cm); and 3" (7.6 cm) p i p e , r e s p e c t i v e l y . Dr ive motor s i z e i s v a r i e d , depending on i m p e l l e r and d i s c h a r g e p i p e s i z e s . The l a r g e r pumps a r e used f o r t r a n s f e r from one k e t t l e t o a n o t h e r , a t a r a t e of 300 t o n s p e r hour (270 m e t r i c ) , w h i l e t h e s m a l l e r pumps a r e used f o r f eed ing l e a d t o t h e v a r i o u s c a s t i n g machines a t a much lower r a t e .
Vacuum d e z i n c e r s a r e of t h e well-known S t . Joseph Lead Company des ign - a submerged b e l l and water cooled condensing top . Impe l l e r s i z e i s s i m i l a r t o s t i r r e r s , b u t a 60HP motor i s used. S e a l i n g of t h e i m p e l l e r s h a f t is accomplished by a v e r t i c a l t u b e d i p p i n g i n t o t h e l e a d b a t h . Vacuum i s provided by a 14" x 14" (36 x 36 cm) Kinney DVD vacuum pump, d r i v e n by a 25HP motor. Vacuum l i n e s a r e s t e e l p i p e and r e i n f o r c e d rubber hose , bo th 3" (7.6 cm) i n d i ame te r . O i l r e - c lamat ion i s done wi th a l o c a l l y des igned u n i t .
F in i shed me ta l i s c a s t on e i t h e r Newnam wheels o r s t r a i g h t l i n e machines. One t o n ( .9 m e t r i c ) i n g o t s a r e c a s t on a 26' d i ame te r (7 .8 meter ) wheel c o n t a i n i n g 25 molds. Vacuum l i f t e r s remove t h e i n g o t s a f t e r a mechanical s tamper h a s i d e n t i f i e d t h e me ta l . A 19 '9" d i ame te r (6 meter ) wheel i s equipped t o c a s t 100 l b . p i g s (45 k g ) . P i g s a r e removed by a mechanica l p i c k e r a f t e r t h e l o t number h a s been stamped. A Sheppard s t r a i g h t - l i n e c a s t i n g machine i s used t o c a s t p lumber ' s l e a d i n 25 l b . (11 kg) l i n k s . A Treadwel l de s igned , s t r a i g h t - l i n e c a s t i n g machine f o r 100 l b . (45 kg) p i g s has a l s o been i n s t a l l e d . The machine c a s t s f o u r p i g s a t once , u s i n g a four- t rough t u n d i s h synchronized wi th mold t r a v e l . Af t e r c a s t i n g and skimming, t h e p i g s a r e cooled by running t h e molds half-submerged through a wa te r b a t h con ta ined i n a pan underneath t h e mold s t r a n d . A f t e r l o t number i d e n t i f i c a t i o n , t h e p i g s a r e a u t o m a t i c a l l y s t a c k e d i n b a t c h e s of 25, 5 t i e r s of 5 each , w i t h a l t e r n a t e t i e r s p l aced a t 90" t o each o t h e r . By p rope r programming, s t a c k s o f 4 , 5 , 6 , o r 7 t i e r s may b e made, and a l t e r n a t e p i g s may b e i n v e r t e d . A f t e r t h e s t a c k i s formed, i t i s d e l i v e r e d a u t o m a t i c a l l y t o a f o r k - l i f t pick-up s t a t i o n . Capac- i t y of t h e u n i t i s 60 t o n s (54 m e t r i c ) p e r hour .
S i l v e r Sec t ion . The s i l v e r recovery s e c t i o n a t Herculaneum pro- duces f i r e r e f i n e d s i l v e r . S i l v e r skims a r e r e t o r t e d i n f o u r tilt- i n g f u r n a c e s u s i n g No. 11 g r a p h i t e r e t o r t s and c a s t i r o n condensers . The r e t o r t f u r n a c e s a r e 5 ' x 6 112' h igh x 4 ' deep (1.5 x 2.0 x 1 .2 me te r ) . Each i s f i r e d by two n a t u r a l gas bu rne r s r a t e d a t 750 x l o 3 B tu /h r (190 x l o 3 kg -ca l /h r ) . The f u r n a c e s a r e l i n e d w i t h 4 112'' (11.5 cm) f i r e b r i c k , backed up by 2" (5 .1 cm) of a s b e s t o s .
The cupe l pan , 44" x 132" x 7" deep (112 x 335 x 1 8 cm), has a c a s t s t e e l p l a t e bottom, water - jacketed s i d e s , and i s comple te ly l i n e d w i t h magnes i te b r i c k . The pan i s enc losed i n a f i r e b r i c k - l i n e d f u r n a c e which i s f i r e d w i t h two n a t u r a l ga s b u r n e r s r a t e d a t
1 . 5 x l o 6 Btu/hr each (378 x l o 3 k g - c a l l h r ) . Bu l l i on is s idecha rged through a t rough. Approximately 2,500 cfm (71 cu meter ) of cupe l l a - t i o n a i r i s s u p p l i e d by a S t u r t e v e n t 114 b lower , powered by a lOHP motor. The depth of t h e b a t h is c o n t r o l l e d by a cha in b lock which t i l t s t h e f u r n a c e , u s i n g t h e t app ing end a s t h e fulcrum.
M a t e r i a l Handling. A l l l e a d shapes a r e handled by f o r k - l i f t t r u c k a f t e r c a s t i n g . Loading equipment c o n s i s t s of e l e v e n b a t t e r y powered o r g a s o l i n e - e l e c t r i c u n i t s .
A major p o r t i o n of t h e l e a d p roduc t ion is banded t o customer s p e c i f i c a t i o n s , u s i n g 314" x .02511 h igh t e n s i l e s t e e l s t r a p p i n g (1.9 x .063 cm), which i s z i n c coa t ed .
Opera t ions .
Two major b rands of l e a d a r e produced a t Herculaneum - "St . Joe" and "Doe Run". The "St . Joe" brand l e a d , c o n t a i n i n g copper and s i l v e r a s t h e major a l l o y i n g e l emen t s , i s t h e n a t u r a l l y o c c u r r i n g a l l o y of l e a d sme l t ed from unblended o r e . The "Doe Run" brand is f u l l y r e f i n e d l e a d of 99.99+% p u r i t y ( s e e Table 11).
S t . J o e Brand Lead. The S t . Joe brand l e a d r e q u i r e s ve ry l i t t l e r e f i n i n g . A normal s u l f u r t r e a t m e n t f o r copper removal t o 0.05% Cu i s s u f f i c i e n t . S i l v e r c o n t e n t is s a t i s f a c t o r y w i t h no t r ea tmen t .
F igu re 14. R e t o r t i n g Opera t ion
Thi s me ta l i s g iven a f i n a l s t i r r i n g w i t h a c a u s t i c soda and n i t r e mix tu re ( 4 : l ) and i s ready f o r c a s t i n g i n t o t h e d e s i r e d shape .
Doe Run Brand Lead. B u l l i o n i s r ece ived from t h e d r o s s p l a n t w i t h .010% o r l e s s coppe r , and about .030% s i l v e r . The s i l v e r con- t e n t ha s been r a i s e d t o t h i s l e v e l by r e c i r c u l a t i o n of r e f i n e r y r e s i d u e s and o t h e r mi sce l l aneous m a t e r i a l .
D e s i l v e r i n g is accomplished by use of a modi f ied Pa rkes p r o c e s s , which i n v o l v e s r e c i r c u l a t i o n of s i l v e r sk ims w i t h i n t h e Re f ine ry . High t empera tu re s i l v e r - d e f i c i e n t skims and low t empera tu re z inc - r i c h skims a r e r e c i r c u l a t e d . A "middling" skim, h i g h i n s i l v e r , 800 - 1 ,000 o z / t o n (approximate ly 3% Ag) i s removed and s tocked . When a s u f f i c i e n t q u a n t i t y h a s accumula ted , i t i s b a t c h - t r e a t e d i n a k e t t l e , and h igh g rade s i l v e r sk ims a r e produced f o r r e t o r t i n g , a s s a y i n g about 1 ,500 o z / t o n (5% Ag). Des i l ve red l e a d c o n t a i n s approximate ly .0003% Ag. New z i n c consumption i s about 21 l b s . / t o n , o r 1%.
Des i lve red me ta l i s pumped t o one of t h e d e z i n c i n g k e t t l e s , hea t ed t o 1 ,050°F (565°C) and vacuum dez inced a t 50 microns Hg. f o r about f i v e hou r s . Feed t o t h e d e z i n c i n g o p e r a t i o n a s s a y s 0.55% Zn, and dez inced l e a d c o n t a i n s about 0.05% Zn. The d e z i n c i n g b e l l i s used o n l y once and t h e d e p o s i t i s removed f o r re-use.
The r e s i d u a l z i n c and o t h e r remain ing i m p u r i t i e s a r e removed i n t h e c a s t i n g k e t t l e s by m u l t i p l e a d d i t i o n s of 100 l b s . NaOH p l u s 25 l b s . NaN03 (45 kg , 11 k g ) .
The m e t a l is now ready f o r c a s t i n g , o r a l l o y i n g , as, customer needs d i c t a t e .
TABLE I1
T y p i c a l Ana lys i s of Lead
S i l v e r copper A s + Sb Zn Fe B i N i + Co Cd
Doe Run (%) S t . Joe (Z)
Treatment of s i l v e r skims f o l l o w s g e n e r a l i n d u s t r y p r a c t i c e . Charges t o t h e r e t o r t s a r e 1 ,200 l b s . skims (550 kg) and 5 l b . coke b r e e z e (2 .3 k g ) . Zinc i s d i s t i l l e d o f f a t 2,000°F (1,090°C) and r eused i n t h e d e s i l v e r i n g o p e r a t i o n . B u l l i o n , c o n t a i n i n g more t h a n
Figure 15. Finished Lead Storage and Shipment Area
2,000 o z / t o n ( 7 % ) , is c a s t f o r cupe l l ing . The r e t o r t cyc le i s 8 - 10 hours.
When enough r i c h b u l l i o n has been accumulated, wi th a content of about 200,000 oz. of s i l v e r (6.0 m e t r i c t o n s ) , t h e cupel i s s t a r t e d . Charging and l i t h a r g e removal proceed a s r a p i d l y a s poss ib le . When the s i l v e r assays 900 f ineness o r b e t t e r , c u p e l l a t i o n i s h a l t e d and the metal i s granula ted. The granules a r e d r i e d and then packaged i n 1 ,500 oz. capac i ty buckets f o r shipment (46.5 kg).
Maintenance.
Maintenance i n the Ref inery i s l i g h t e r than t h a t performed i n t h e heavy smel t ing s e c t i o n s of the p l a n t . K e t t l e s a r e welded a s c racks develop, and have a u s e f u l l i f e of about four yea r s . The d e s i l v e r - i n g k e t t l e s t ake the wors t punishment, and a f t e r repeated cracking and r e p a i r , a r e used f o r o t h e r l e s s r igorous opera t ions i n the Refinery. Pumps, s t i r r e r s , and f o r k - l i f t t rucks r e q u i r e h igh main- tenance, whi l e o t h e r u n i t s r e q u i r e somewhat l e s s . The Ref inery mainta ins a l l f o r k - l i f t equipment i n i t s own r e p a i r shop, b u t a l l o t h e r maintenance i s provided by t h e main shops.
FUME AND DUST COLLECTION
The Herculaneum Smelter u t i l i z e s baghouses t o c o l l e c t dus t and fume. Two baghouses, con ta in ing 9,360 bags, handle process gases.
Ventilation 20.000 c f rn (567 cu meter)
144 000 c f m 2-175,000 c t m
(4,080cu meter) ( 4 , 9 5 0 ~ ~ meter] 300 hp
7'01a. (2 . lmeter)~toinless
I S,inter Machine I 5'0ia. (1.5meter)Stainless
60,000 cf m ( 1 , 7 0 0 ~ ~ meter) AC l D PLANT 60 hp
A t h i r d baghouse hand les high-SO2 gases from t h e s i n t e r machine, through 1,152 bags , p r i o r t o e n t e r i n g t h e Acid P l a n t c i r c u i t . The gas hand l ing flow s h e e t i l l u s t r a t e s t h e c i r c u i t .
Number 2 baghouse c o n t a i n s 4,752 bags , 5" i n d iameter x 9 '6" long (12.7 cm x 2.9 meter) , i n 12 c e l l s of 396 bags p e r c e l l . Number 3 baghouse con ta ins 4,608 bags , 8" i n d iameter x 21'6" long (20 cm x 6 .55 m e t e r ) , i n 12 c e l l s of 384 bags p e r c e l l . Number 4 baghouse c o n t a i n s 1 ,152 bags , 8" i n d iameter x 21'6" long (20 cm x 6.55 me te r ) , i n 6 c e l l s of 192 bags p e r c e l l . A l l bags a r e a c r y l i c 2 x 2 t w i l l w i t h an o r i g i n a l p o r o s i t y of 55-65 cfrn p e r 1 /2" water gauge p r e s s u r e (156-184 cu meter p e r minute p e r 1.27 cm water p reksure ) . A l l baghouses were des igned and b u i l t by t h e Wheelabrator Company.
Number 2 baghouse, b u i l t i n 1954, c o n t a i n s 59,675 sq . f t . of c l o t h a r e a t o f i l t e r 136,000 cfrn of gas (5,500 s q . me te r s ; 3,850 cu meter lmin) , f o r a gas:bag r a t i o of 2 .29 : l . Two f a n s , each r a t e d a t 78,000 cfrn (2,200 cu meterlmin) a t 7" wa te r gauge (17.8 cm) running a t 1,200 r.p.m. handle c l e a n gas and keep t h e baghouse under s u c t i o n . The shaking c y c l e and o u t l e t damper o p e r a t i o n a r e au tomat i ca l ly con- t r o l l e d by a programmed timer. Dust is c o l l e c t e d i n i n v e r t e d cone bottom hoppers and removed through a r o t a r y v a l v e and 12" (30.5 cm) screw conveyor.
Number 3 baghouse, b u i l t i n 1962, c o n t a i n s 185,856 sq. f t . of c l o t h t o f i l t e r 350,000 cfrn (17,300 sq . meter ; 9,900 cu meterlmin) f o r a gas:bag r a t i o of 1 .89 : l . Two f a n s , r a t e d a t 175,000 cfrn a t 8" water gauge (4,950 cu meterlmin, 20.3 cm), running a t 880 r.p.m. ex- h a u s t c l e a n gas and p rov ide s u c t i o n . A r e p r e s s u r i z i n g f a n , running a t 2,380 r .p .m. , prov ides 17,000 cfrn a t 11" water gauge (480 cu rneterlmin, 28 cm). Operat ion of t h e o u t l e t dampers, shaking, and r e p r e s s u r i z i n g a r e c o n t r o l l e d a s i n Number 2 baghouse. Hopper con- s t r u c t i o n and d u s t removal a r e a l s o s i m i l a r .
Number 4 baghouse, b u i l t i n 1969, c o n t a i n s 42,240 sq . f t . of c l o t h t o f i l t e r 60,000 cfm (3,940 s q . m e t e r ; 1,700 cu meter) f o r a gas:bag r a t i o of 1 .42: l . The Acid P l a n t blower p rov ides t h e neces- s a r y s u c t i o n . Shaking o p e r a t i o n s and d u s t removal a r e similar t o Numbers 2 and 3 baghouses.
There is no Number 1 baghouse; i t was abandoned and removed i n 1963.
Dust product hand l ing is by screw conveyor from vee bottom hop- p e r s , through a r o t a r y va lve , i n t o c o l l e c t i o n . screw conveyors which move t h e d u s t t o a double s h a f t , b laded pugging u n i t . Water, i n s u f f i c i e n t q u a n t i t y t o p reven t d u s t i n g , i s added t o t h e pugger. The dampened d u s t is bottom-discharged i n t o a r a i l r o a d c a r f o r t r a n s p o r t t o t h e s i n t e r p r e p a r a t i o n s e c t i o n v i a t h e r o t a r y c a r dumper.
P e r i o d i c a s says of dust-make a r e performed. I f t h e cadmium con-
t e n t i s s u f f i c i e n t , t h e m a t e r i a l i s r e se rved f o r cadmium recovery e lsewhere .
Typ ica l a s say of d u s t : Pb - 60% Cd - 3-5% Zn - 10%
A l l baghouse o u t l e t f a n s d i s c h a r g e i n t o t h e b a s e of a b r i c k s t a c k , 352' h i g h w i t h a d i ame te r of 20' (108 x 6 . 1 me te r ) .
ACID PLANT
The new S u l f u r i c Acid P l a n t went on s t r e a m i n J u l y , 1969, and i s o p e r a t i n g a t i t s des igned r a t e , producing up t o 340 t o n s (305 m e t r i c ) p e r day of 100% H2S04 from s i n t e r gas . The f low s h e e t i l l u s t r a t e s t h e equipment and p roces s .
The c o n d i t i o n i n g chamber of r e i n f o r c e d c o n c r e t e , 50' x 20' x 1 2 ' h i g h (15 x 6 .1 x 3.66 m e t e r ) , i s equipped w i t h au toma t i c h igh p re s - s u r e w a t e r s p r a y s t o c o n t r o l t h e tempera ture . The s p r a y s o p e r a t e a t 20 gpm and 500 p s i g (78 l i t r e @ 35 kg/sq . cm). The baghouse is de- s c r i b e d p r e v i o u s l y , b u t i t should be no ted h e r e t h a t t h e i n t e r n a l c o n s t r u c t i o n f e a t u r e s a double w a l l , w i t h c l e a n f i l t e r e d gas p a s s i n g
F igu re 17. Acid P l a n t
A C I D PLANT FLOW SHEET
Figure 18, Acid Plant Flow Sheet
through t h e i n t e r p a c e t o mainta in t h e baghouse s t e e i work above t h e dewpoint of t h e gas. A t e f l o n and b r i c k scrubbing tower, 15' i n d i - ameter x 37' (4.5 x 11.3 me te r ) , is p a r t i a l l y f i l l e d wi th r i n g s and is opera ted w i t h 1 ,500 gpm sp rays a t a 75' head (5,700 l i t res @ 22.8 meter) . Scrubber l i q u o r i s cooled w i t h wa te r i n g r a p h i t e h e a t ex- changers. The scrubbed gas passes through two 132 tube e l e c t r o - s t a t i c m i s t p r e c i p i t a t o r s . Each tube is 10'' i n diameter x 1 5 ' long (25 cm x 4.5 meter) . The m i s t p r e c i p i t a t o r i s l i n e d wi th s h e e t l e a d , and i s se rved by a 60 k i l o w a t t , 500 mi l l iampere t r ans fo rmer r e c t i f i e r . The drying tower, 17 ' i n d iameter x 33' (5.2 x 1 0 me te r ) , is l i n e d wi th 4" (10 cm) of a c i d proof b r i c k , w i th an 8" (20 cm) bottom of the same m a t e r i a l , and is packed w i t h 3" r i n g s (7.6 cm).
Dry gas is converted i n a 4-pass conver t e r wi th hea t exchange be- tween each pass . The c a t a l y s t i s V205, and t h e f o u r passes con ta in a t o t a l of 54,500 litres. SO2 gas i s absorbed i n 98% H2S04 i n a 17 ' d iameter x 30' tower (5.2 x 10 meter) s i m i l a r t o t h e d ry ing tower and t h e scrubbing tower. Hot a c i d product ion is cooled i n c a s t i r o n c o o l e r s us ing e x t e r n a l l y c i r c u l a t e d water . The coo l ing wa te r is i n c losed c i r c u i t w i t h a L i l l i e Hoffman induced d r a f t coo l ing tower designed t o cool 4,000 gpm from 100°F t o 86°F (15,000 l i t res from 43°C t o 30°C). D i spe r s ion Strengthened Lead (DSL) has been used i n the p l a n t f o r SO2 sampling l i n e s , and i n t h e l i q u o r c o o l e r and one - m i s t p r e c i p i t a t o r a s c o n s t r u c t i o n m a t e r i a l , t o e v a l u a t e t h e improved p r o p e r t i e s and extended l i f e of t h i s m a t e r i a l .
A n a t u r a l gas f i r e d fu rnace is provided f o r pre-heat be fo re s t a r t - u p s .
The major p o r t i o n o f t h e a c i d is shipped by barge on the Mississ- i p p i River. Barge loads average 1 ,500 tons (1,350 m e t r i c ) . A load- i n g f a c i l i t y has been b u i l t , which can load 500 tons (450 m e t r i c ) p e r hour. Minor tonnages of a c i d a r e shipped i n r a i l tank c a r s and by road t r a n s p o r t .
MAINTENANCE AND ENGINEERING
Maintenance is provided f o r the p l a n t by two types of crews. The S i n t e r P l a n t , B l a s t Furnace-Dross a r e a , and au tomot ive / fo rk - l i f t s e c t i o n have t h e i r own i n t e r n a l maintenance groups. The ba lance of t h e p l a n t u t i l i z e s t h e main shop crews. The shops a r e s t a f f e d w i t h e l e c t r i c i a n s , we lde r s , p a i n t e r s , c a r p e n t e r s , mach in i s t s , p i p e f i t t e r s , b lacksmiths , and s h e e t meta l men. A comprehensive appren t i cesh ip program provides t h e needed t r a i n e d personnel on a cont inuing b a s i s .
Scheduled maintenance is performed i n t h e S i n t e r P l a n t and Blas t Furnace-Dross a r e a s , augumented, a s needed, by shop pe r sonne l , wh i l e t h e balance of t h e p l a n t ope ra te s on a "work r e q u e s t H b a s i s . Af ter - noon and n igh t s h i f t s a r e c a t e r e d f o r by a sma l l crew on each of t h e s e s h i f t s .
The S i n t e r P l a n t has i n s t i t u t e d a "Planned ~ a i n t e n a n c e " schedule incorpora t ing p reven t ive maintenance and c o r r e c t i v e replacement of u n i t s . The rep laced u n i t s a r e renewed i n t h e shops and a r e a v a i l - a b l e f o r t h e nex t changeover. This program has enabled the S i n t e r P l a n t t o o p e r a t e i n excess of 90% of a v a i l a b l e time.
Engineering s t u d i e s a r e performed provided they a r e n o t too l a rge . An engineer ing and drawing o f f i c e is a v a i l a b l e t o make engineer ing drawings. Large s c a l e p r o j e c t s a r e genera l ly con t rac ted wi th out- s i d e c o n s u l t a n t s and engineer ing s e r v i c e companies.
LABORATORIES
A l l chemical l a b o r a t o r i e s a t t h e Herculaneum Smelter a r e housed i n one bu i ld ing . Besides o f f i c e and s t o r a g e a r e a s , t h e r e a r e rooms f o r t h e spectrometer , t h e assay-furnace, t h e atomic-absorption apparatus and t h e a n a l y t i c a l balances . There a r e two wet-chemistry l a b o r a t o r i e s - the l a r g e r l abora to ry performs most of the product ion ana lyses , whi le t h e smal le r l abora to ry handles s p e c i a l analyses .
Four graduate chemists and f i v e t echn ic ians work day s h i f t , seven days a week, t o provide t h e smel te r opera t ing personnel wi th t h e informat ion necessary t o c o n t r o l the p l a n t p rocesses and t h e q u a l i t y of the f i n i s h e d products .
I n a d d i t i o n t o t h e convent ional wet-chemical techniques , the lab- o r a t o r y f o r c e makes use of a Baird-Atomic, 3 meter , model HB-2, Direct-Reading Spectrometer, wi th a model RS-1 Readout Console and a t e l e t y p e p r i n t - o u t ; a model 303 Perkim-Elmer Atomic Absorption Spectrophotometer wi th a Perkin-Elmer Recorder Readout and a Honey- w e l l Electronik-19 Recorder; and a "fire-assay" furnace which uses n a t u r a l gas a s f u e l .
A l l incoming raw m a t e r i a l s a r e assayed as necessary. P a s t ex- pe r ience d i c t a t e s whether every l o t is analyzed o r i f only an oc- c a s i o n a l a n a l y s i s i s necessary. Concentrates ge t t h e g r e a t e s t amount of a t t e n t i o n ; each l o t is analyzed f o r lead. Monthly com- p o s i t e s of each type of concen t ra te a r e analyzed f o r minor elements. Spec ia l a t t e n t i o n is given t o t h e slag-producing elements and those elements which may contaminate t h e f i n i s h e d metal.
Chemical c o n t r o l of t h e b l a s t furnace, d ross fu rnace , and s in - t e r i n g p l a n t is maintained by analyzing t h e s l a g , mat te , and s i n t e r d a i l y . Weekly and monthly composites of t h e d a i l y samples provide an i n t e r n a l check on d a i l y a n a l y s i s , a s w e l l as providing informa- t i o n f o r m e t a l l u r g i c a l balance.
The r e f i n e r y process is almost exc lus ive ly c o n t r o l l e d by u t i l i z i n g t h e spectrometer . S i l v e r , z inc , and copper con ten t s a r e c l o s e l y watched. Finished metal is a l s o analyzed f o r a r s e n i c , antimony, t i n ,
bismuth, cadmium, and i r o n . Analysis of t h e a l l o y i n g elements i s done on t h e spect rometer o r by wet-chemistry, whichever provides t h e necessary accuracy i n meeting customer's s p e c i f i c a t i o n s . De- velopment work i s cons tan t ly be ing done t o improve a n a l y t i c a l curves and sampling procedures i n o rde r t o i n c r e a s e spect rometer pe r fo r - mance. I n i t i a l work has i n d i c a t e d t h a t s i n t e r , ma t t e , and s l a g can be run on t h e spect rometer . Having t h e a b i l i t y t o run such m a t e r i a l s quickly and p r e c i s e l y w i l l i n c r e a s e t h e c o n t r o l of p l a n t opera t ions .
RESEARCH
The Research Department i s made up of graduate engineers and tech- n i c i a n s . The scope of t h e i r a c t i v i t i e s should perhaps be desc r ibed a s development and p i l o t p l a n t work, r a t h e r than pure r e sea rch , be- cause t h e i r p r o j e c t s a r e c l o s e l y t i ed - in t o t h e opera t ion of t h e p l a n t .
I n r e c e n t y e a r s , t h e r e sea rch group has conducted i n v e s t i g a t i o n s i n t o va r ious a s p e c t s of p l a n t metal lurgy, inc lud ing up-draft s i n t e r - i n g , mois ture c o n t r o l of t h e S i n t e r P l a n t charge, gas a n a l y s i s , and sampling systems. Other i n v e s t i g a t i o n s inc lude determining t h e forms of l ead i n b l a s t furnace s l a g and modif ica t ions of p r a c t i c e i n such r e f i n e r y opera t ions a s decoppering, d e s i l v e r i n g , dezincing, e t c .
A f u l l s c a l e r e sea rch and development program was c a r r i e d ou t on d i r e c t smel t ing of concen t ra tes t o produce m e t a l l i c l ead i n a one s t e p conver te r opera t ion . This included a p i l o t s c a l e opera t ion of t h e process and r e s u l t e d i n Pa ten t s being granted f o r t h e process .
The Research Department, i n a d d i t i o n t o tu rn ing ou t smal l quant i - t i e s of s p e c i a l t y a l l o y s where t h e amounts involved a r e too smal l f o r r e g u l a r p l a n t f a c i l i t i e s , s u p p l i e s s t andard a l l o y s f o r t h e spec- t rograph i n the a n a l y t i c a l l abora to ry . A metal lographic and mechan- i c a l t e s t i n g l abora to ry i s used f o r in -p lan t c o n t r o l and product development.
The resea rch group runs gas volume surveys i n va r ious t r a i l s about t h e p l a n t , i n a d d i t i o n t o running dus t burde'ns and ana lyses of t h e gas streams. A s e r i e s of ambient a i r monitoring s t a t i o n s sur- rounding t h e p l a n t is maintained by t h e Research Department, a s w e l l a s a smal l network of in -p lan t a i r sampling s t a t i o n s .
GENERAL
The Herculaneum Lead Smelting Divis ion i s the only l ead smel t ing opera t ion of t h e S t . Joe Minerals Corporation.
The t o t a l complement i s approximately 540 - - 80 s a l a r y and s t a f f employees; 460 hour ly pa id employees. The smel te r opera tes seven
days p e r week, on a 24-hour-per-day b a s i s .
I n 1969, the f i r s t f u l l yea r of opera t ion a t expanded capac i ty , t h e p l a n t produced 223,000 tons (201,000 met r i c ) of r e f i n e d lead.
ACKNOWLEDGEMENT
The au thor wishes t o thank the S t , Joe Minerals Corporation fo r permission t o publish, and the staff a t Herculaneum f o r t h e i r a s s i s t ance .
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