better etp performance in view of zinc technology

8/18/2019 Better ETP Performance in View of Zinc Technology

1/31


2/31

Birla In!tit"te of Technology an$ Science; Pilani

ACKNOWLEDGEMENT

I wo"l$ li/e to e=pre!! my !incere than/! to Birla In!tit"te of Technology an$

Science for giving me thi! won$erf"l opport"nity to "n$ergo a training program at

thi! pre!tigio"! organi>ation8

I wo"l$ li/e to e=pre!! my gratit"$e to :r8 Si$$arth Bener?ee; the 7nit 4ea$ an$

&ra!im In$"!trie! for allowing me to $o thi! pro?ect8

I am than/f"l to .r8 0apil 9hat"rve$i for g"i$ing me thro"gho"t the pro?ect an$

provi$ing me all the nece!!ary $ata an$ al!o coor$inating with other $epartment!

for me8

I am al!o than/ to :r8 Samir 0ale; my in!tr"ctor for hi! g"i$ance $"ring thi!

practice !chool II program witho"t which it wo"l$ not have #een a !"cce!! an$ a!

goo$ a learning e=perience a! thi!8

.eepa/ 0a!hyap

:8E8 9hemical Engineering

.epartment of 9hemical Engineering

Birla In!tit"te of Technology an$ Science; Pilani


3/31

CERTIFICATE

Thi! i! to certify that .eepa/ 0a!hyap have !"cce!!f"lly complete$ the Practice

School II pro?ect on the topic @Better ETP performance in view of Zinc

Technology "n$er o"r &"i$ance a! a part of the partial f"lfillment of the co"r!e8

Dr. Kapil Chaturvedi :anager; Effl"ent Treatment Plant *ETP+

&ra!im In$"!trie!


4/31

BIRLA INSTITTE OF TEC!NOLOG" AND SCIENCE

#ILANI $RA%AS!TAN&

#RACTICE SC!OOL DI'ISION

Stati() &ra!im In$"!trie!


5/31

BIRLA INSTITTE OF TEC!NOLOG" AND SCIENCE

#ILANI $RA%AS!TAN&

#RACTICE SC!OOL DI'ISION RESPONSE OPTION SHEET

Stati()- &ra!im In$"!trie! ation8

Si0)ature (* Stude)t Si0)ature (* #S Fa/ult2

.eepa/ 0a!hyap :r8 Samir R 0ale


6/31

:8E8 9hemical Engg8 BITS PS-II ac"lty

9ontent!

SR8 NO8 PARTI97ation Tan/

581 Ne"trali>ation Tan/

58( Primary 9larifier

585 Aeration Tan/

J

J

J

)

)

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7/31

586 Secon$ary 9larifier

58' Sl"$ge Thic/ener

58 Belt Pre!!

58J Ka!tewater .i!po!al

32

32

32

68 Propo!e$ Zn technology 33

'8 Role of >inc in !pinning proce!! 3(

8 inc "!ing thiopho!phinic e=tractant

12

38 proce$"re for the $etermination of aci$; >inc; an$

magne!i"m in wa!te water

11

3J8 9oncl"!ion 15

3)8 Reference 15

3. Gra+im i)du+trie+ Ltd.


8/31

&ra!im i! a flag!hip company of the A$itya Birla &ro"p an$ i! to$ay a $ominant

player in the man"fact"ring of Gi!co!e Staple i#er *GS+; an e=tremely ver!atile

te=tile fi#re that ha! characteri!tic! !imilar to cotton8 The "nit wa! e!ta#li!he$ in

3)65 with pro$"ction capacity of 36 TP. with Plant E%"ipment importe$ from

.o#!on Barlow of 7808

The plant ha! grown organically with c"rrent in!talle$ capacity of 536 TP.8 Kith

"!e of entirely in$igeno"! re!o"rce! incl"$ing raw material!; /now-how an$

e%"ipment &ra!im ha! emerge$ a! one of the worl$L! mo!t co!t-efficient GS

pro$"cer!8

The man"fact"ring facility i! locate$ clo!e to river 9ham#al at Nag$a *:P+; a

!mall town e=actly mi$ ,way on the rail ro"te from New .elhi to :"m#ai8

The company ha! al!o e!ta#li!he$ an engineering $ivi!ion to man"fact"re the plant

an$ machinery "!e$ for pro$"cing GS an$ i! a ma?or e=porter to !o"th ea!t an$

far ea!tern co"ntrie!8

The 9ompany i! committe$ to innovation an$ creativity an$ ha! !ignificant

!trength! in Re!earch .evelopment8 In colla#oration with the Birla Re!earch

In!tit"te for Applie$ Science! at Nag$a; the 9ompanyL! R. team! en$eavo"r to

ma/e technology wor/8 Thi! i! very important !ince GS man"fact"ring proce!! i!

highly energy inten!ive an$ it! contri#"tion to total co!t of pro$"ction i! appro=83186M8 The company ha! it! own thermal plant for electricity nee$!8

&ra!im to$ay i! a $ominant player in the 'i+/(+e Staple Fi,er $'SF+ !egment an$

thi! i! partic"larly commen$a#le #eca"!e of it! "!e of entirely in$igeno"! re!o"rce!

incl"$ing raw material!; /now-how an$ e%"ipment8 An innovative an$ re!earch-

oriente$ organi>ation; &ra!im ha! emerge$ a! one of the worl$L! mo!t co!t-

efficient GS pro$"cer! $"e to it! integrate$ operation!8

&ra!im i! al!o In$iaL! large!t pro$"cer of So$i"m S"lphate , a #ye-pro$"ct of GS

man"fact"re8 Thi! chemical i! "!e$ wi$ely in paper p"lp; $etergent; gla!! an$

te=tile! in$"!trie!8

P"lp i#er B"!ine!! contri#"te! !ignificantly to the National E=che%"er #y way

of E=ci!e $"ty an$ al!o to In$iaL! foreign e=change re!erve! thro"gh e=port of P"re

an$ Blen$e$ arn a! well a! fa#ric! an$ :a$e-"p! #a!e$ on GS8


9/31

ig83 :an"fact"ring Proce!! of GS

4. Ba+i/ #ri)/iple+ (* Ra2() Fi,er #r(du/ti()

Rayon i! man"fact"re$ #y three $ifferent chemical proce!!e!; namely the vi!co!e

proce!!; the cell"lo!e acetate proce!!; an$ the c"prammoni"m proce!!8 In In$ia

mo!t of the "nit! pro$"ce vi!co!e rayon8 In the pro$"ction of rayon; p"rifie$ cell"lo!e i! chemically converte$ into a !ol"#le compo"n$8 A !ol"tion of

thi! compo"n$ i! pa!!e$ thro"gh the !pinneret to form !oft filament! that are then

converte$ or @regenerate$ into almo!t p"re cell"lo!e8 Beca"!e of the reconver!ion

of the !ol"#le compo"n$ to cell"lo!e; rayon i! referre$ to a! a regenerate$ cell"lo!e

fi#er8

There are !everal type! of rayon fi#er! in commercial "!e to$ay; name$ accor$ing

to the proce!! #y which the cell"lo!e i! converte$ to the !ol"#le form an$ then

regenerate$8 Rayon fi#er! are wet !p"n; which mean! that the filament! emerging

from the !pinneret pa!! $irectly into chemical #ath! for !oli$ifying or regeneration8

Gi!co!e rayon i! ma$e #y converting p"rifie$ cell"lo!e to =anthate; $i!!olving the

=anthate in $il"te ca"!tic !o$a an$ then regenerating the cell"lo!e from the pro$"ct

a! it emerge! from the !pinneret8 :o!t rayon i! ma$e #y the vi!co!e proce!!8

5. 'i+/(+e #r(/e++

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10/31

:o!t commercial rayon man"fact"ring to$ay "tili>e! the vi!co!e proce!!8 Thi!

proce!! $ate! to the early 3)22!; with mo!t of the growth in pro$"ction occ"rring

#etween 3)16 an$ 3)668 In the early perio$; pro$"ction wa! mainly te=tile

filament; altho"gh the fir!t !taple wa! pro$"ce$ in 3)3'8 4igh performance rayon!;

!"ch a! tire cor$; $i$ not appear "ntil the late 3)(2!; with the a$vent of hot-

!tretching an$ a$$ition of larger amo"nt! of >inc to the !pin #ath8 Invention of

mo$ifier! in 3)5 #ro"ght on !"per tire cor$! an$ mar/e$ the #eginning of the

high-performance rayon fi#er!8

All of the early vi!co!e pro$"ction involve$ #atch proce!!ing8 In more recent

time!; proce!!e! have #een mo$ifie$ to allow !ome !emi-contin"o"! pro$"ction8

or ea!ier "n$er!tan$ing; the vi!co!e proce!! i! a #atch operation8 9lic/ on each

proce!! !tep for a #rief e=planation8

5.3 Cellul(+e

P"rifie$ cell"lo!e for rayon pro$"ction "!"ally come! from !pecially proce!!e$

woo$ p"lp8 It i! !ometime! referre$ to a! @$i!!olving cell"lo!e or @$i!!olving

p"lp to $i!ting"i!h it from lower gra$e p"lp! "!e$ for paperma/ing an$ other

p"rpo!e!8 .i!!olving cell"lo!e i! characteri>e$ #y a high -cell"lo!e content;i.e8;

it i! compo!e$ of long-chain molec"le!; relatively free from lignin an$

hemicell"lo!e!; or other !hort-chain car#ohy$rate!8

ig81 9ell"lo!e

5.4 Steepi)0

The cell"lo!e !heet! are !at"rate$ with a !ol"tion of ca"!tic !o$a *or !o$i"m

hy$ro=i$e+ an$ allowe$ to !teep for eno"gh time for the ca"!tic !ol"tion to

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11/31

penetrate the cell"lo!e an$ convert !ome of it into @!o$a cell"lo!e; the !o$i"m !alt

of cell"lo!e8 Thi! i! nece!!ary to facilitate controlle$ o=i$ation of the cell"lo!e

chain! an$ the en!"ing reaction to form cell"lo!e =anthate8

*9'432O6+n nNaO4 *9'4)O5ONa+n n41O

5.5 #re++i)0

The !o$a cell"lo!e i! !%"ee>e$ mechanically to remove e=ce!! ca"!tic !o$a

!ol"tion8

5.6 Shreddi)0

The !o$a cell"lo!e i! mechanically !hre$$e$ to increa!e !"rface area an$ ma/e the

cell"lo!e ea!ier to proce!!8 Thi! !hre$$e$ cell"lo!e i! often referre$ to a! @white

cr"m#8

5.7 A0i)0

The white cr"m# i! allowe$ to !tan$ in contact with the o=ygen of the am#ient air8

Beca"!e of the high al/alinity of white cr"m#; the cell"lo!e i! partially o=i$i>e$

an$ $egra$e$ to lower molec"lar weight!8 Thi! $egra$ation m"!t #e caref"llycontrolle$ to pro$"ce chain length! !hort eno"gh to give managea#le vi!co!itie! in

the !pinning !ol"tion; #"t !till long eno"gh to impart goo$ phy!ical propertie! to

the fi#er pro$"ct8

5.8 9a)thati()

The properly age$ white cr"m# i! place$ into a ch"rn; or other mi=ing ve!!el; an$

treate$ with ga!eo"! car#on $i!"lfi$e8 The !o$a cell"lo!e react! with the 9S1 to

form =anthate e!ter gro"p!8 The car#on $i!"lfi$e al!o react! with the al/alineme$i"m to form inorganic imp"ritie! which give the cell"lo!e mi=t"re a

characteri!tic yellow color , an$ thi! material i! referre$ to a! @yellow cr"m#8

Beca"!e acce!!i#ility to the 9S1 i! greatly re!tricte$ in the cry!talline region! of

the !o$a cell"lo!e; the yellow cr"m# i! e!!entially a #loc/ copolymer of cell"lo!e

an$ cell"lo!e =anthate8


12/31

*9'4)O5ONa+n n9S1 *9'4)O5O-S9-SNa+n

5.: Di++(lvi)0

The yellow cr"m# i! $i!!olve$ in a%"eo"! ca"!tic !ol"tion8 The large =anthate

!"#!tit"ent! on the cell"lo!e force the chain! apart; re$"cing the interchain

hy$rogen #on$! an$ allowing water molec"le! to !olvate an$ !eparate the chain!;

lea$ing to !ol"tion of the otherwi!e in!ol"#le cell"lo!e8 Beca"!e of the #loc/! of

"n-=anthate$ cell"lo!e in the cry!talline region!; the yellow cr"m# i! not

completely !ol"#le at thi! !tage8 Beca"!e the cell"lo!e =anthate !ol"tion *or more

acc"rately; !"!pen!ion+ ha! a very high vi!co!ity; it ha! #een terme$ @vi!co!e8

5.; Ripe)i)0

The vi!co!e i! allowe$ to !tan$ for a perio$ of time to @ripen8 Two important

proce!!e! occ"r $"ring ripening Re$i!tri#"tion an$ lo!! of =anthate gro"p!8 The

rever!i#le =anthation reaction allow! !ome of the =anthate gro"p! to revert tocell"lo!ic hy$ro=yl! an$ free 9S18 Thi! free 9S1 can then e!cape or react with

other hy$ro=yl on other portion! of the cell"lo!e chain8 In thi! way; the or$ere$; or

cry!talline; region! are gra$"ally #ro/en $own an$ more complete !ol"tion i!

achieve$8 The 9S1 that i! lo!t re$"ce! the !ol"#ility of the cell"lo!e an$ facilitate!

regeneration of the cell"lo!e after it i! forme$ into a filament8

*9'4)O5O-S9-SNa+n n41O *9'432O6+n n9S1 nNaO4

5.< Filteri)0


13/31

The vi!co!e i! filtere$ to remove "n$i!!olve$ material! that might $i!r"pt the

!pinning proce!! or ca"!e $efect! in the rayon filament8

5.3= De0a++i)0

B"##le! of air entrappe$ in the vi!co!e m"!t #e remove$ prior to e=tr"!ion or they

wo"l$ ca"!e voi$!; or wea/ !pot!; in the fine rayon filament!8

5.33 Spi))i)0 *Ket Spinning+

The vi!co!e i! force$ thro"gh a !pinneret; a $evice re!em#ling a !hower hea$ with

many !mall hole!8 Each hole pro$"ce! a fine filament of vi!co!e8 A! the vi!co!e

e=it! the !pinneret; it come! in contact with a !ol"tion of !"lf"ric aci$; !o$i"m

!"lfate an$; "!"ally; Zn ion!8 Several proce!!e! occ"r at thi! point which ca"!e

the cell"lo!e to #e regenerate$ an$ precipitate from !ol"tion8 Kater $iff"!e! o"t

from the e=tr"$e$ vi!co!e to increa!e the concentration in the filament #eyon$ the

limit of !ol"#ility8 The =anthate gro"p! form comple=e! with the Zn which $raw

the cell"lo!e chain! together8 The aci$ic !pin #ath convert! the =anthate f"nction!

into "n!ta#le =antheic aci$ gro"p!; which !pontaneo"!ly lo!e 9S1 an$ regenerate

the free hy$ro=yl! of cell"lo!e8 *Thi! i! !imilar to the well-/nown reaction of

car#onate !alt! with aci$ to form "n!ta#le car#onic aci$; which lo!e! 9O1+8 There!"lt i! the formation of fine filament! of cell"lo!e; or rayon8

*9'4)O5O-S9-SNa+n Cn41SO5 *9'432O6+n n9S1 CnNa1SO5

5.34 Dra>i)0

The rayon filament! are !tretche$ while the cell"lo!e chain! are !till relatively

mo#ile8 Thi! ca"!e! the chain! to !tretch o"t an$ orient along the fi#er a=i!8 A! the

chain! #ecome more parallel; interchain hy$rogen #on$! form; giving the filament!the propertie! nece!!ary for "!e a! te=tile fi#er!8

5.35 Wa+hi)0

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14/31

The fre!hly regenerate$ rayon contain! many !alt! an$ other water !ol"#le

imp"ritie! which nee$ to #e remove$8 Several $ifferent wa!hing techni%"e! may #e

"!e$8

5.36 Cutti)0

If the rayon i! to #e "!e$ a! !taple * i.e.; $i!creet length! of fi#er+; the gro"p of

filament! *terme$ @tow+ i! pa!!e$ thro"gh a rotary c"tter to provi$e a fi#er which

can #e proce!!e$ in m"ch the !ame way a! cotton8

ig8( 9hemical Reaction involve$ in GS Proce!!

6. ET# pre+e)t +tatu+


15/31

Effl"ent! get generate$ in the proce!! at !everal point! an$ can #e cla!!ifie$ "n$er

three #roa$ hea$!; i8e8 al/aline; aci$ic an$ ne"tral8 The ma?or !o"rce! of

wa!tewater generation from plant incl"$e proce!!; cooling; #oiler fee$; cleaning;

floor wa!hing an$ $ome!tic $i!charge!8 Total wa!tewater generate$ from all the

a#ove !o"rce! for e=i!ting pro$"ction i! 16;222 mQF$8 The contaminant! from thevario"! !o"rce! "n$ergo change! when the effl"ent !tream! merge with one

another8 The merger of aci$ic an$ al/aline effl"ent! re!"lt! in partial ne"trali>ation

of aci$ity8 9ell"lo!e pre!ent in a $i!!olve$ !tate in the al/aline effl"ent i!

regenerate$ an$ remain! a! !"!pen$e$ matter in the a#ove effl"ent8 The "nit ha!

in!talle$ a f"ll-fle$ge$ Effl"ent Treatment Plant *ETP+ #a!e$ on primary treatment

of ne"trali>ation an$ clarification followe$ #y !econ$ary treatment $e!igne$ on the

principle of e=ten$e$ aeration activate$ !l"$ge proce!!8 Thi! i! !"pplemente$ with

a ca!ca$e aerator an$ a poli!hing pon$8 The effl"ent generate$ from $ifferent!tream! i8e8 aci$ic; al/aline an$ ne"tral !tream i! ta/en to the e%"ali>ation tan/

thro"gh preliminary treatment8

6.3 E?uali@ati() Ta)

9om#ine effl"ent from preliminary treatment i! ta/en to the e%"ali>ation tan/ of

$iameter 3(86 m an$ !i$e water $epth (82 m8 :ain p"rpo!e of e%"ali>ation i! to

ta/e care of variation in flow an$ characteri!tic! of $ifferent !tream! #y mi=ing the

effl"ent!8 The e%"ali>e$ flow i! ta/en to the ne"trali>ation tan/8

6.4 Neutrali@ati() Ta)

The e%"ali>e$ flow i! ne"trali>e$ in thi! tan/8 A tan/ of $iameter 3'8J m an$ !i$e

water $epth 18( m i! "!e$ for thi! p"rpo!e where a$e%"ate %"antity of lime i!

a$$e$8 .o>ing of -32 M lime !l"rry i! reg"late$ to maintain p4 of 82 to 868

9alci"m !"lphate form! in accor$ance with the following reaction

41SO5 9a *O4+ 1 9aSO5 141O

The !l"rry containing precipitate$ calci"m !"lphate goe! to !l"$ge Thic/ener an$

i! then mi=e$ with !l"$ge of Primary clarifier8 The overflow i! ta/en to the primary

clarifier for f"rther treatment8

6.5 #rimar2 Clari*ier


16/31

Two n"m#er! of primary clarifier! are in!talle$ for primary treatment8 The flow

from ne"trali>ation tan/ i! ta/en to the primary clarifier 3 for removal of !ettla#le

!oli$!8 The $iameter of primary clarifier 3 i! (586 m an$ !i$e water $epth i! (85 m8

The !l"$ge !ettle$ at the #ottom of the tan/ i! contin"o"!ly ta/en to !l"$ge

thic/ener for thic/ening with the help of !crapper!8 Scrapper! p"!h the !l"$gealong the tan/ #ottom to collecting channel8 Primary clarifier 1 i! /ept a! a !tan$#y

"nit8 The overflow from primary clarifier n"m#er 3 i! ta/en for a com#ine$

#iological treatment after a$$ition of "rea an$ .AP a! n"trient! for the meta#olic

activitie! of the micro-organi!m!8

6.6 Aerati() Ta)

Biological treatment a$opte$ i! activate$ !l"$ge proce!! with e=ten$e$ aeration

!y!tem compri!ing of an aeration tan/ of !i>e J'82 m = 56 m = ( m having thirteenn"m#er! of 12 hp an$ nine n"m#er! of 52 hp !"rface aerator!8 Ka!tewater with p4

val"e aro"n$ 82 having n"trient! in the ratio of BO. N P *32263+ i! fe$ to

aeration tan/8 Re%"ire$ concentration of @:i=e$


17/31

Settle$ !l"$ge from primary an$ !econ$ary clarifier i! ta/en to the !l"$ge thic/ener

for re$"ction of vol"me8 Thi! !l"$ge generate$ i! con!i!ting mainly of cell"lo!ic

matter an$ contain! heat potential8 The thic/ene$ !l"$ge i! tran!ferre$ to the #elt

pre!! for f"rther $ewatering8

6.: Belt #re++

The!e are the !l"$ge $ewatering $evice! that involve the application of chemical

con$itioning; gravity $rainage an$ mechanically applie$ pre!!"re to $ewater the

!l"$ge8

9on$itione$ !l"$ge i! fir!t intro$"ce$ on a gravity $rainage !ection where it i!

allowe$ to thic/en8 ollowing the gravity $rainage; pre!!"re i! applie$ in a low-

pre!!"re !ection; where the !l"$ge i! !%"ee>e$ #etween oppo!ing poro"! cloth

#elt!8 The final $ewatere$ !l"$ge ca/e i! remove$ from the #elt! #y !craper #la$e!8

Two "nit! of #elt pre!! are provi$e$ in the ETP8

6.; Wa+te>ater Di+p(+al

The Treatment Plant i! f"nctioning on contin"o"! #a!i!8 The %"antity of the

effl"ent treate$ in the Effl"ent Treatment Plant for e=i!ting pro$"ction i!

16222mQF$8 after en!"ring the %"ality of water it i! relea!e$ in the 9ham#al River8


18/31

ig85 low $iagram of ETP

7. #r(p(+ed ) te/h)(l(02

There i! the compari!on #etween the two chemical al"m an$ >inc "!e$ in

man"fact"ring vi!co!e rayon

Al"m ZincEco-frien$ly 4a>ar$o"!

cheap 9o!tly


19/31

ig86 9ro!! !ectional view of the fi#er! of al"m proce!!

ig8' 9ro!! !ection view of the fi#er of >inc proce!!

8. R(le (* @i)/ i) +pi))i)0 pr(/e++


20/31

The !e%"ence of phy!ical an$ chemical tran!formation! ta/ing place at !pinning

i! e=tremely comple= an$ !till not f"lly characteri>e$8 The main reaction i! clearly

reformation of cell"lo!e from !o$i"m cell"lo!e =anthate #y the action of !"lph"ric

aci$;

1 cell"lo!e,O 9S1 Na 41SO5 1 cell"lo!e,O4 Na1SO5 19S1

4owever; thi! follow! the tran!ient formation of the more !ta#le >inc cell"lo!e

=anthate in certain region!; with a$$itional more comple= !pecie! al!o #eing

forme$ if vi!co!e mo$ifier! are "!e$8 Zinc !"lphate i! !ol"#le "p to aro"n$ p4 J86;

!o thi! material penetrate! into the forming filament! ahea$ of ne"trali>ation

*reaction (85 a#ove+8 4owever; after the initial formation of >inc cell"lo!e =anthate

*followe$ rapi$ly #y regeneration to cell"lo!e+ in the o"ter region! of the filament!;

f"rther penetration i! #elieve$ to #e impe$e$ #y the formation of other >inc !pecie!

!"ch a! Zn*O4+1 an$ ZnS8 4ence the formation of a tran!ient region of >inc

cell"lo!e =anthate i! overta/enL #y the penetration of aci$8

The region in which >inc cell"lo!e =anthate ha! forme$ i! #elieve$ to #e

re!pon!i#le for the !/in effect which can #e !een in rayon fi#re cro!!-!ection!8

The !/in region retain! $ye #eca"!e of a greater $egree of cry!tal !tr"ct"re relative

to the core8 The tran!ient >inc comple= i! #elieve$ to ai$ the formation of greater

cry!tallinity #y $elaying regeneration relative to !o$i"m cell"lo!e =anthate *the

>inc variant i! more !ta#le+; an$ po!!i#ly al!o #y cro!!-lin/ing #etween

neigh#oring cell"lo!e chain!; allowing greater orientation to #e achieve$8

Beca"!e of the effect of >inc on cry!tallinity; which "ltimately tran!late! to

improve$ ten!ile !trength; the pro$"ction of high !trength rayon "!"ally involve!

high level! of >inc in the !pin#ath8 :o!t plant! "!e #etween 286 an$ 386M >inc

!"lphate in the !pin#ath for reg"lar !taple pro$"ction8 Below 286M; a !ignificant

$eterioration in fi#re ten!ile re!"lt! which can to !ome e=tent #e recovere$ #y

rai!ing !o$i"m !"lphate concentration an$ re$"cing the aci$ concentration8 At very

low level! of >inc in the !pin#ath; the filament cro!!-!ection #ecome! very

irreg"lar; with only a !mall amo"nt of !/in #eing apparent8

:. Literature +urve2


21/31

The ."tch 4olima proce!! precipitate! the >inc a! the car#onate on inert n"clei

which can #e !creene$ off an$ $i!car$e$8 A patent $e!cri#e! the "!e of !o$i"m

car#onate or #icar#onate to precipitate >inc car#onate8 It i! recommen$e$ for

vi!co!e rayon !ol"tion! in which the ratio of the weight percentage! of >inc an$

!"lph"ric aci$ i! at lea!t 3(8

Precipitation of the >inc "!ing lime i! well /nown an$ ha! #een "!e$ in plant !cale

for year! in E"rope an$ the 78S8 B"t; a $en!e; recovera#le >inc precipitate ha!

never #een mentione$8 7!"ally; com#ine$ plant wa!te! are treate$ with lime; an$

the re!"lting !l"$ge containing >inc; calci"m; cell"lo!e; etc8; i! $i!car$e$ to

lagoon!8

Ion e=change proce!!e! appear fre%"ently in the literat"re8 Some of their $i!a$vantage! are

38 The effl"ent; !till highly aci$; ha! to #e ne"trali>e$ anyway #efore $i!charge8

18 Aci$ an$ !o$i"m ion! compete for the a$!orption of >inc on the re!in;

re$"cing it! capacity a! m"ch a! 62M when the !o$i"m an$ hy$rogen ion!

amo"nt to 36 gram!Fliter8 A !pill of concentrate$ aci$ #ath m"!t #e collecte$ an$

$il"te$ with !oft water #efore it reache! the re!in8

(8 9ertain amine! an$ !pinning agent! poi!on the re!in an$ re$"ce it! capacity8

58 Efficient a$!orption of imp"ritie! !"ch a! calci"m; magne!i"m; iron; lea$;

copper; etc8; often prevent re"!e of the >inc witho"t f"rther chemical !eparation!8

68 The efficiency of >inc removal i! low8 By "!ing a recycle re-generation !y!tem;

the efficiency of recovery will average )1M8

A R"!!ian proce!! may #e mentione$8 It precipitate! an$ $i!car$! the >inc a! >inc

!"lfi$e #y "!ing hy$rogen !"lfi$e from the wa!te rayon !pinning ga!e!8

A &erman proce!! "!e! an activate$ !l"$ge !y!tem to re$"ce the >inc content of

wa!te water! to ' - 32 mg8 Fl8 It wa! more effective in har$ water!8 The >inc i!

$i!car$e$ together with the #iological !l"$ge8


22/31

An$; of co"r!e; if the concentration of >inc an$ other chemical! warrant! it; the

aci$ wa!te !ol"tion! can #e concentrate$ #y evaporation an$ then re"!e$8 or

!team economy; m"ltiple effect evaporator! are prefera#ly employe$8

;. Re/(ver2 +2+tem (* i)/

Zinc i! "!e$ a! regeneration retar$ant in the aci$ !pinning #ath8 Beca"!e it i! not

con!"me$ in any of the vi!co!e reaction!; the "!e$ >inc repre!ent proce!! lo!!e!;

thro"gh $rag o"t #y the filament! to the !"#!e%"ent wa!h !tream!; filter

#ac/wa!hing; !pla!he!; lea/!; an$ the wa!hing of e%"ipment8 The effect! of >inc a!

a poll"tant are well $oc"mente$8 9oncentration! a! low a! 382 mgF< have #een

!hown to #e harmf"l to fi!h8 In a$$ition; there i! !ome evi$ence in$icating that >inc

ha! a !ynergi!tic property when a!!ociate$ with copper8

Altho"gh it ha! #een /nown that >inc can #e precipitate$ from aci$ wa!te !tream!

#y the "!e of lime; the re!"ltant !l"$ge ha! #een of low >inc a!!ay; contaminate$

with other compo"n$!; an$ with very poor !ettling characteri!tic!8 In commercial

operation!; the !l"$ge pre!ente$ a $i!po!al pro#lem an$ recovery of >inc !"ita#le

for recycle wa! impo!!i#le8

The >inc in the !l"$ge wa! recovere$ an$ recycle$ to the rayon man"fact"ring

plant8 Thi! recycling of >inc wa! !hown to have no ill effect! on the rayon yarn8

Thi! proce!! greatly enhance! the economic! of removing thi! !o"rce of >inc

poll"tion; allowing ne"trali>ation of the aci$ !tream an$ recovery of the >inc while

generating a goo$ profit for in$"!trial yarn! an$ at a mo$erate co!t for te=tile

yarn!8

#r(/e++

The /ey to thi! >inc recovery proce!! i! a two-!tage precipitation; with the !econ$ precipitation ta/ing place "n$er caref"l p4 control; "!ing !o$i"m hy$ro=i$e in

contact with circ"lating !l"rry of >inc hy$ro=i$e cry!tal!8 All of the >inc

precipitate! in the !econ$ !tep; mo!t of the imp"ritie! in the fir!t8 The element! of

the proce!! are a! follow!8 Aci$ an$ al/aline wa!te !tream! are collecte$ in a

ne"trali>ation tan/8 4ere !"fficient lime i! a$$e$ to rai!e the p4 to '828 At thi!


23/31

point; no >inc hy$ro=i$e will precipitate #"t a portion of the iron; calci"m !"lfate;

an$ other imp"ritie! will form a light precipitate8 Kith a coag"lant ai$; the mi=t"re

i! !ent to a clarifier where a clear overflow containing the $i!!olve$ >inc i!

o#taine$8

Thi! clear overflow i! contacte$ in a reactor with a circ"lating !tream of previo"!ly

precipitate$ !l"$ge containing >inc hy$ro=i$e8 The p4 i! rai!e$ !"#!e%"ently to )86

to 3282 with !o$i"m hy$ro=i$e8

The #"l/ of the >inc precipitate! onto the e=i!ting cry!tal! in the circ"lating !l"rry8

At !tea$y-!tate con$ition!; the with$rawal rate of the circ"lating !l"rry !tream i!

ma$e e%"ivalent to that of the >inc #eing a$$e$8 Thi! $en!e !l"$ge i! then !ettle$8

The !ettle$ !l"$ge of 5 to M >inc a!!ay i! converte$ #ac/ to >inc !"lfate with

!"lf"ric aci$ an$ !ent #ac/ to the !pinning #ath8 If $e!ire$; the !l"$ge can #efiltere$ or centrif"ge$ to 3JM !oli$! #efore $i!!olving with aci$8

The >inc content of the overflow water from the $en!ator-reactor i! !et #y the p4,

!ol"#ility relation!hip of >inc in water an$ re!"lt! in >inc content of 286 to 3 mgF<

at p4 328 Once the precipitate$ >inc i! remove$ from the wa!tewater; the p4 can

#e rea$?"!te$ to a lower val"e8


24/31

ig8 .en!ator

3=. The E/()(mi/+

The conventional techni%"e for removing >inc from the !pinning aci$ wa!te !tream

ha! #een $irect lime precipitation to Up4 32; with no >inc recovery8 The economic!

of recovery are a very !trong f"nction of the amo"nt of >inc "!e$ in the preparation

of the yarn an$ the ratio of aci$ to >inc in the !pinning #ath8 In man"fact"ring

in$"!trial yarn! an$ tire cor$!; it i! common to "!e 586 to 86 /g of >inc per 322 /g

of yarn8 Thi! high concentration of >inc ma/e! recovery e=tremely attractive8

Te=tile yarn! "!e le!! >inc; an$ altho"gh recovery i! !till the mo!t economic

!ol"tion; it offer! le!! of a ret"rn8 The!e two ca!e! are pre!ente$ a! e=treme!; with

many plant! falling #etween the two val"e!8

33. Area+ (* Appli/ati()

Thi! technology; with only !mall mo$ification! to conform to local plant

con$ition!; co"l$ have imme$iate application in any vi!co!e rayon plant with


25/31


26/31

The concentration of >inc in !pin#ath i! aro"n$ 5622ppm8 After the generation of

fi#er !ome amo"nt of >inc carryover to ne=t !tage with fi#er8 rom the e=periment

it !how! it i! 62ppm that come! in ETP after fir!t wa!h8

or 3 ton of fi#er; it re%"ire 32 m

(

water for wa!hing

or 522 ton of fi#er; it re%"ire 5222 m( water for wa!hing

That 5222 m( effl"ent come in ETP that contain 62ppm >inc a! >inc !"lphate

Amo"nt of >inc

5222=62122222 gm Zn 122/g Zn a! ZnSO5F$ay

The main reaction

ZnSO5 1NaO4 Zn *O4+1 Na1SO5

The reaction !how! that J2gm of NaO4 re%"ire reacting with 3'385gm of ZnSO5

in that >inc i! '68(Jgm; to give ))8(Jgm of Zn *O4+1 a! precipitate 8

or 122/g Zinc or 5)(8)5/g ZnSO5 it re%"ire! 15685(J/g of NaO4 to give

(2582'J/g of Zn *O4+1 a! precipitate8

If the efficiency of that proce!! i! )2M mean! 12/g or 6ppm >inc will #e there after

treatment; that will #e $il"te$ to 6 time! *3ppm+ after mi=ing with other !tream of 12222m(F$ay

The efficiency of the >inc recovery proce!! $epen$! on the concentration of the

!ol"#le >inc in the aci$ fee$8 Thi! i! $"e to the fact that "nle!! there i! an

a#normality in the .en!ator operation; !"ch a! an acci$ental low p4; the !ol"#le

>inc in the clear effl"ent remain! e!!entially con!tant8 Therefore; the higher the

!ol"#le >inc concentration in the fee$; the higher the percent efficiency of >inc

recovery8

35. ET# AFTER MODIFICATION


27/31

ig8) mo$ifie$ ETP

36. EFFLENT WATER ALIT"

The effl"ent water i! normally very clear8 It $oe! contain a#o"t 1;222 - 1;622 ppm

of $i!!olve$ !o$i"m !"lfate; which i! pre!ent in the fee$ to the plant; an$

!omewhat le!! than 1;222 ppm of $i!!olve$ calci"m !"lfate; cor- re!pon$ing to the

!ol"#ility of gyp!"m in the pre!ence of thi! amo"nt of !o$i"m !"lfate8 Thi! water i!

!"ita#le for re"!e wherever the high !"lfate an$ high har$ne!! i! not an

impe$iment for e=ample; a! cleaning an$ fl"!hing water; p"mp !eal water; etc8 It

ha! #een "!e$ for all water nee$! in the >inc recovery plant e=cept for lime !la/ing

an$ $il"ting water; an$ for the !afety !hower an$ eye wa!h !tation8

Any "n"!e$ effl"ent water !ho"l$ #e mi=e$ with other plant effl"ent! to re$"ce it!

p4 of )86 - 3282; or aci$ifie$ in !ome ine=pen!ive way8

37. RESE OF INC


28/31

The recovere$ >inc ha! #een "!e$ for many month! in the rayon plant8 Beca"!e the

>inc contain! !ome magne!i"m; it i! "!e$ in a rayon #ath that contain! #oth >inc

an$ magne!i"m8 Thi! #ath i! the !ame one that contri#"te! the magne!i"m to the

recovery plant fee$8

38. OT!ER #ROCESSES

38.3 S(lve)t e1tra/ti() pr(/e++

Recovery of >inc from the effl"ent ha! !"cce!!f"lly #een accompli!he$ "!ing

!olvent e=traction8 In the proce!!; >inc i! e=tracte$ to more than )6M *p41+ with

$i-ethyl he=yl pho!phoric aci$ *.E4PA+ $i!!olve$ in /ero!ene in two or three

!tage!8 Stripping i! performe$ with a !"lph"ric aci$ !ol"tion8 By a$?"!ting the net

flow rate of the !trip !ol"tion; the concentration of >inc in !ol"tion may #eincrea!e$ to 62 gFl or more8 Th"!; the re!"lting >inc !"lphate !ol"tion can #e re-

"!e$ $irectly in the !pinning #ath8

ig832 E=traction of Zinc from wea/ aci$ effl"ent!

38.4 Re/(ver2 (* @i)/ u+i)0 thi(ph(+phi)i/ e1tra/ta)t


29/31

A proce!! ha! #een $evelope$ for the recovery of >inc from rayon wa!te effl"ent

following !olvent e=traction techni%"e "!ing thiopho!phinic e=tractant! 9yane=

11 an$ (218 Before recycling of >inc !"lphate !ol"tion in !pinning #ath; !ol"tion

m"!t #e free from calci"m; which i! $eleterio"! to the proce!! a! gyp!"m

precipitate! an$ form! !cale8 The e=tractant 9yane= (21 ha! #een fo"n$ !elective

for the recovery of ))8))M of >inc in the form of [R 1Zn org from the effl"ent a#ove

e%"ili#ri"m p4 (85 maintaining the OFA ratio of 3F(2 leaving all the calci"m in the

raffinate8 The >inc from the loa$e$ 9yane= (21 can #e !trippe$ with 32M !"lph"ric

aci$ at even OFA ratio of 328 The !trippe$ !ol"tion th"! o#taine$ co"l$ #e recycle$

in the !pinning #ath of the rayon plant an$ raffinate co"l$ #e $i!po!e$ !afely

witho"t affecting environment


30/31

3:. #ROCEDRE FOR T!E DETERMINATION OF ACID INC AND

MAGNESIM IN WASTE WATER

A9I.

:ea!"re 322 ml8 of !ample into a 162 ml8 Erlentneyer fla!/; a$$ ( or $rop! of

(6M hy$rogen pero=i$e; an$ let !tan$ for ( or 5 min"te!8 A$$ 1 or ( $rop! of

:ethyl Re$ in$icator; an$ titrate with NF32 NaO48

9alc"lation Titration = 283 = 2825) = 322F322 M41SO5

ZIN9

A$$ 32 ml8 of maleic aci$ - !o$i"m maleate #"ffer !ol"tion *p4 '8J+; an$ 5 to J

$rop! of Eriochrome Blac/ T in$icator to the titrate$ !ol"tion "!e$ for aci$

$etermination8 Titrate with 2821 $i!o$i"m ver!enate !ol"tion to a color change

8from p"rple-re$ to p"rple-#l"e8 9alc"lation Titration = '86 p8 p8m8 a! Zn8

:A&NESI7:

A$$ 36 ml8 of ammonia - ammoni"m chlori$e #"ffer !ol"tion *p4 322+ to the

titrate$ !ol"tion from the aci$ an$ >inc $etermination!8 Titrate with 2821 N

$i!o$i"m ver!enate !ol"tion! to appro=imately J2M of the e=pecte$ titration8 A$$

1 to 5 $rop! of Eriochrome Blac/ T in$icator an$ contin"e the titration to a !/y-

#l"e color

9alc"lation Titration = 185 p8p8m8 a! :g8


31/31

3;. C()/lu+i()

The following concl"!ion! can #e $rawn from thi! !t"$y

• The efficient an$ economical recovery an$ re"!e of wa!te !ol"#le >inc from

vi!co!e rayon plant wa!te! ha! #een proven "n$er in$"!trial con$ition!

•

The efficiency of the precipitation an$ recovery of !ol"#le >inc e=cee$!)6M; which i! higher than that of other /nown metho$! !"ch a! ion

e=change8

• The effl"ent water from the recovery plant i! e=tremely clear water of

con!tant; !lightly al/aline p4 an$ it i! e!!entially free of to=ic metal content8

• It can #e re"!e$ to a$vantage where it! high har$ne!! an$ !alt content i! not

an impe$iment; !"ch a! water for fl"!hing an$ cleaning p"rpo!e!; p"mp !eal

water; etc8 It! !ol"#le >inc content i! le!! than 1 ppm8

3inc an$ !eparation of calci"m "!ingthiopho!phinic e=tractant :808 Dha G8 0"mar; .8 Bagchi; R8D8 Singh; Dae-ch"n

better etp performance in view of zinc technology

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