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# OAR Box 

# 1814
Prepped by Ollie Stewart



### Document

Number: 

# 43 ) ll-B-2 1
Docket Number: 

# A-88-0 2

Printed 11/7/2008 7:22:08 AM

Sheet 43 of 63( ^ ) P. 2 

## A-88-0 2 "j£ - & - Z. \

MIDWES T RESEARC H INSTIT U 450 5 Creedmoo rH

e Raleigh

. N C Telephon e (919 ) 7

8

Date : Marc h16 , 198 7

(Finalize d Apri l 2 , 1987 ) Subject : Sit e Visit—Reliabl e Platin g Company

Chromiu m Electroplatin g NESHA P EP A Contrac t 68-02-3817 ; ESE D Projec t 85/02 a MR I Projec t 7717- K
From : Robi nBarker j^VTo : A l Vervaer t

ESED/ISB/SS S (MD-13 ) U . S . Environmenta l Protectio nAgenc y Researc hTriangl e Park , N.C . 2771 1
I . Purpos e Th e purpos e o f thi s sit e visi t wa s t o gathe r backgroun d Informatio n abou t th e chromi c aci d anodizin g operatio na t thi s plan t an d t o asses s visuall y th e amoun t o f mistin g from th e chromi c ad d anodizin g tank . II . Plac e an

d Dat e Reliabl e Platin g an

d Polishin g Company , Inc . Pos t Offic e Bo

x421 7 8 0 Bisho p Avenu e Bridgeport , Connecticu t 0660 7 (203 ) 366-526 1 Decembe r 18 , 198 6
III . Attendee s Reliabl e Platin g Company Bo bMorris , Plan t Maintenanc e Auggl e Dattolo , Proces s Enginee r U . S . Environmenta l Protectio nAgenc y (EPA )
A l Vervaert , IS B Midwes t Researc hInstitut e Robi nBarke r

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IV . Discussio n Th e plan t visi t bega nwit ha discussio nabou t th e chromi c ad d anodizin g operation . Th e discussio nwa s followe db y a tou r o f th e facility . A . Genera l Reliabl e Platin g Company 1 s a jo bsho pengage dprimaril y 1 nchromi c aci danodizin g o f aircraf t an dmiscellaneou s parts . Decorativ e chromiu m platin g an

dothe r platin g operation s ar e als o performe da t thi s plant . Reliabl e Platin g Compan y 1 s a certifie dUnite dState s militar y contractor . Th e platin g sho p1 s operate d8 hour s per day , 5 day s per week . B . Proces s Descriptio n Th e on e chromi c ad danodizin g tank a t thi s facilit y 1 s configure d a s show n1 nFigur e 1 . Th e chromi c ad danodizin g proces s consist s o f th e followin g steps : alkalin e cleaning , col dwate r rinse , nitri c ad ddip , col dwate r rinse , anodizing , an dnicke l acetat e sealin g and/o r ho t wate r sealing . Th e aluminu

m frequentl y

1 s dye dafte r sealing . Th e anodizin g H n e 1 s equippe dwit ha nautomati c hois t t o transfe r part s int o an dou t o f th e proces s tanks . Th e anodizin g solutio ncontain s chromi c aci d1 na concentratio no f approximatel y

6 0 t o 7 5 gram s pe r lite r ( 8 t o 1 0 ounce s per gallon ) o f water . Th e operatin g temperatur e range s fro m 35 ° t o 38° C (95 ° t o 100°F) . Th e anodizin g tank 1 s 3. 5 meter s (m ) (11. 5 fee t [ft] ) long , 0.6 1 m (2. 0 ft ) wide , an

d0.9 1 m (3. 0 ft ) dee pan

dha s a capacit y

o f approxi matel y 1,89 3 liter s (50 0 gallons ) o f anodizin g solution . Th e tank 1 s equippe dwit ha 4,000-amper e rectifier . Th e voltag e 1 s applie dstep-wis e unti l a leve l o f 4 0 volt s i s reached . Thi s leve l 1 s applie dfo r th e remainde r o f th e anodizin g time . Th e curren t typicall y range s fro

m 20 0 t o 30 0 amperes , an

dth e anodizin g time 1 s approximatel y 1 hour . C . Emissio nContro l Th e anodizin g tank 1 s equippe dwit ha double-side ddraf t hoodt o captur e th e chromi c ad dmist . Th e ventilatio nhood1 s ducte dt o a we t scrubbe r manufacture db y Neihau s Brothers , Inc . Th e scrubbe r 1 s locate d adjacen t t o th e anodizin g tank . Th e Niehau s scrubbe r 1 s a fume exhaus t an dseparatin g uni t develope d primaril y

fo r th e electroplatin g an dchemica l industries . Th e scrubbin g actio n1 s achieve db

y a combinatio no f wate r absorptio nan dcentrifuga l separation . Figur e 2 i s a schemati c o f th e Niehau s scrubber . It s operatio ni s describe db y Niehau s a s follows :-= » => DRAI N LEGEN D AIRFLO W

VENTILATIO N HOOD S AI RSTREA M OUTLE T

AI RSTREAM INLE T SCRUBBE R

Figur e 1

. Schemati c o f chromi c aci d anodizin g tank

.



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WATE R INLE T

INTAK E STAC K SPRA Y CHAMBE R

SEPARATIN G CHAMBE R

BLOWE R

DRAI N OUTLE T

Figur e 2 . Centrifugal-flo w scrubbe r manufacture db y Niehau s Brothers , Inc .



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".. . contaminate dai r i s draw ni nthroug hth e Intak e duc t Int o whfc hspray s o f wate r ar e introduced . Thes e sprays , upo nImpingin g o nth e highspee dblowe r whee l ar e reduce dt o fo g whic hIntimatel y mi xwit hth e contaminate dair , dissolvin g th e contaminants . Th e blowe r whee l bein g axlall y locate dwithi nth e separatin g chambe r als o act s a s th e Impelle r o f a centrifuge , thereb y separatin g th e wate r entraine dcontaminant s whic har e draine da t th e botto m o f th e unit . Th e cleane dai r spiral s ou t th e discharg e locate da t th e top. " Th e desig nga s flow

rat e o f th e scrubbe r 1 s 8 5 cubi c meter s pe r minut e (3,00 0 cubi c fee t pe r minute) . Th e desig nwate r flow rat e range s from

7. 6 t o 11. 4 liter s pe r minut e ( 2 t o 3 gallon s pe r minute) . Th e scrubbe r wate r 1 s no t recycle dan

dth e scrubbe r 1 s continuousl y spraye dwit hfres h water . Th e scrubbe r wastewate r 1 s combine dwit hothe r wast e stream s an d1 s draine dt o a wastewate r treatmen t system . Sulfu r dioxid e 1 s use dt o pretrea t th e wastewate r t o reduc e th e hexavalen t chromiu m t o trivalen t chromium . Afte r pretreatment , th e wastewate r 1 s pumpe dt o a clarifie r wher e a polyme r 1 s adde dcausin g th e heav y metal s t o precipitat e a s sludg e an dsettl e t o th e botto

m o f th e tank . Clea nwate r 1 s the ndraw nof f th e top . Th e sludg e 1 s pumpe dt o a pres s wher e 1 t 1 s compresse dInt o a cake . V . Observation s A smal l amoun t o f gassin g occurre da t th e side s o f th e tank (cathode ) an

daroundth e workpiec e (anode ) whil e th e tank wa s 1 n operation . However , th e ga s di dno t appea r t o be breakin g throug hth e platin g solutio nsurface . Ther e wa s n o chromi c ad dvisibl e o na piec e o f clea nwhit e pape r tha t wa s hel dove r th e bat hfo r a shor t perio do f time . VI . Conclusion s Th e Reliabl e Platin g Compan y plan t 1nBridgeport , Connecticut , 1 s representativ e o f a smal l jobsho ptha t perform s chromi c ad danodizin g o f aircraf t an

dmiscellaneou s parts . T o determin e th e desirabilit y o f performin g emission s testing , i t 1 s recommende dtha t a chromiu m mas s balanc e b e performe do nth e chromi c aci danodizin g operatio nb y collectin g sample s o f th e once-throug hscrubbe r wate r t o determin e 1 f th e quantit y o f chromi c ad dtake nup1 nth e scrubbe r wate r Indicate s whethe r emission s appea r t o b e significant . I f th e result s o f th e mas s balanc e sho w tha t chromi c ad demission s fro m anodizin g tank s ar e negligible , no furthe r testin g woul db e performed . However , 1 f th e result s o f th e mas s balanc e indicat e tha t chromi c ad demission s ma y b e significant , emission s testin g o nth e anodizin g bat hwil l b e recommended . VII . Referenc e 1 . Niehau s Brothers , Inc. , Neihau s Fum e Separators , Indianapolis , Indiana . 1986 .