Descripsi process Direct Neutralization oe Synthetic Manufacture
Raw materials Basis : 1000 Kg of Ammonium Sulfate Ammonia 30% = 800 kg Sulfur acid (0%! = 00 kg Sources of raw material Silfur acid can "e o"tained "# contact $rocess as descri"ed in module : & 'ecture 18 Reaction : )*3 + *S, -. ()*! S, Ammonium sulfat made wit/ manufactured ammonia is called s#nt/etic ammonium sulf sulfat at Bot/ Bot/ satu satura rato tor rss and and 2r#s 2r#sta tall lli ier erss are are em$l em$lo# o#ed ed in t/e t/e s#nt/ s#nt/et etic ic manuf manufact actur uree of ammonium sulfat 4/e /eat of reaction of an/#drous ammonia and concentrated sulfur acid o"tained "# contact $rocess is 5er# /ig/ *ence water e5a$orated from t/e cr#stallier must "e returned eit/er "# means of a condenser c ondenser or "# addition of water Ammonia and sulfur acid are introduced 5ia t/e slurr# rec#cle line 6/erein t/e# react and su$er/eat t/e rec#cling slurr# 4/e slurr# is su"se7uentl# flas/ed in t/e u$$er c/am"er at a reduc reduced ed $ressu $ressure re
(0 (0 9 80 80 mm of *g! *g! 4/e 4/e eot eot/e /erm rmic ic /eat of rect rectio ion n is remo5e remo5ed d "#
e5a$orating water eit/er $resent in t/e feed acid or added to t/e s#stem for tem$erature control of t/e $rocess 4/e loss of water in t/is one su$ersaturates t/e slurr# w/ic/ recirculates to t/e
lower sus$ension 5essel 5ia an internal $i$e and comes into contact wit/ small cr#stals and nuclei 4/is induces t/ermal s#$son and or "# an eternal $um$ 4/is t#$e of cr#stallier is generall# know as ; kr#stal or ; ,slo unit
n anot/er t#$e of reduced $ressure cr#stallier wit/ a draft tu"e "attle unit& growing r#stals are "roug/t to t/e flas/ing slurr# At t/is surface& su$er saturation induces maimum cr#stal grwt/& and sufficient nuclei are $resent to minimie t/e scale formation inside t/e un it Se5eral t#$es of atmos$/eric $ressure units are $referred to a 5accum cr#stallier "ecause of t/eir sim$licit# and lower ca$ital cost Ammonia is added 5ia a ?et-t#$e mier or a s$arger tu"e >n anot/er design& a sim$le a"sor$tion column incor$orating a few large slotted "u""le 9 /oods is used >n some ot/er case & a single 5essel is em$lo#edfor "ot/ reaction and cr#stalliation and t/e /eat of reaction is remo5ed "# e5a$oration water 4/ere are design w/ere se$arate 5essel for reaction and cr#stalliation are used for eas# o$eration and closer control An o$timum "alance "etween t/e cooling air energ# and t/e #ield of cr#stal is o"tained w/en t/e cr#stalliation tem$erature is in t/e range @3 to @@ 2 >n most case & t/e $roduct is reco5ered from ammonium sulfate slurr# "# continuous or automatic "at/ t#$e centrifuge 4/e $roduct is was/ed wit/ water and 5er# dilute and s$in dried again "efore dr#ing
or small out$ut& to$-feed filters are used since t/e $roduct can "e se$arated& was/ed and dried in single e7ui$ment Ammonium sulfate li7uor is corrosi5e and watted $arts of t/e e7ui$ment are made of stainless steel or ru""er lined mild steel 4o im$ro5e t/e s/a$e and sie& modifiers are used& suc/ as tri5alent metallic salts Small amount of $/os$/oric acid or arsenic com$ounds are added as corrosion in/i"itors Sum"er : Dr. N .K Patel. Ammonium Sulfate . Natubhai V. Patel College of Pure & Applied Sciences B.Sc. Semester V Industrial chemistr !Vocational" #S$%CICV$' (ea) and *ine Inorganic chemicals .modul + lecture ,$. -amis / april $01 pu-ul 0.%+ pm
Ammonium Sulfate Can Be Synthesized Directly or Produced as a Byproduct
Ammonium sulfate was one of t/e first $o$ular fertiliers& $rimaril# "ecause it was $roduced as a "#$roduct of coke o5ens as earl# as 183 6/ile it is still widel# used& it /as "een su$$lanted somew/at "# urea and ot/er fertiliers t/at $romote green growt/ in $lants >t is still often used as a com$onent in man# fertilier "lends Ammonium sulfate can "e $roduced as a "#$roduct of ca$rolactam (see Section & 4/e B4 2/ain!& as a coke o5en "#$roduct& or "# direct s#nt/esis A t#$ical flow diagram for t/e s#nt/etic $rocess is s/own in igure -@ >n t/is $rocess& an/#drous ammoia and sulfur acid are com"ined in a $i$e reactor A /ig/l# aot/ermic reaction occurs& $roducing ammon ium sulfate and a "isulfate solution
Ammonium sulfate cr#stals are formed "# circulating t/e solution t/roug/ an e5a$orator w/ere it t/ickens A centrifuge se$arates t/e cr#stals from t/e mot/er li7uor 4/e cr#stals contain 1 $ercent to $ercent moisture& and are dried in a fluidied "ed or rotar# drum dr#ert s/ould "e dr# and $refera"l# /a5e "elow 01% free moisture )o free acidit# s/ould "e cooled wit/ dr# air under controlled condition after dr#ing& $articularl# w/en t/e am"ient tem$erature and /umidit# are sufficient /ig/ to cause su"se7uent moisture condensation after cooling in a "ulk storage $ile or in sealed "ags Ammonium sulfate is commonl# s/i$$ed in $ol#et/#lene or $a$er "ags
4/e ma?orit# of its $roduction is coming from coking of coal as a "#$roduct Ammonium sul$/ate is $roduced "# t/e direct reaction of concentrated sul$/uric acid and gaseous ammonia and $roceeds according to t/e following ste$s 1. Reaction of Ammonia and Sulphuric Acid:
'i7uid ammonia is e5a$orated in an e5a$orator using 1@ "ar steam and $re/eated using low $ressure steam 4/e stioc/iometric 7uantities of $re/eated gaseous ammonia and concentrated sul$/uric acid (8% wtEwt! are introduced to t/e e5a$orator 9 cr#stalliser (o$erating under 5acuum! 4/ese 7uantities are maintained "# a flow recorder controller and $ro$erl# mied "# a circulating $um$ (from u$$er $art of t/e cr#stalliser to t/e e5a$orator! 2. Crystallization
4/e reaction takes $lace in t/e cr#stallier w/ere t/e generated /eat of reaction causes e5a$oration of water making t/e solution su$ersaturated 4/e su$ersaturated solution settles down to t/e "ottom of cr#stalliser w/ere it is $um$ed to 5acuum metallic filter w/ere t/e A S cr#stals are se$arated& w/ile t/e mot/er li7uor is rec#cled to t/e cr#stalliser 3. Dryin of the !et Ammonium Sulphate Crystals
4/e wet AS cr#stals are con5e#ed ("# "elt con5e#ors! to t/e rotar# dr#er to "e dried against /ot air (steam /eated! and t/en con5e#ed to t/e storage area w/ere it naturall# cooled and "agged 4/e following $resents t/e $rocess "lock diagram for ammonium sul$/ate $roduction
Ammonium sulphate containing 21% nitrogen is anot/er im$ortant nitrogenous
fertilier >t can "e o"tained as a by-product or ma# "e manufactured synthetically Ammonium sul$/ate is o"tained as a "#-$roductF in t/e steel industr# in w/ic/ ammonia (anot/er "#-$roduct!-from coke o5ens is a"sor"ed in sul$/uric acid Ammonium sulphate is also manufactured "# reacting s#nt/etic ammonia wit/
sul$/uric acid Waste streams from 5arious c/emical and metallurgical industries are ot/er sources of ammonium sul$/ate eg ammonia leac/ing of ores& $roduction of $igments and s#nt/etic fi"res& manufacture of ca$rolactam etc $roduce "# $roductF solutions containing ammonium sul$/ate
lue gases are anot/er source of t/e ammonium sul$/ate 4/e metallurgical smelters and
coal "urning $ower $lants li"erate large 7uantities of S, t/at $ollute t/e atmos$/ere 4/e sul$/ur dioide is collected and con5erted into sul$/uric acid& Ammonium sul$/ate is t/en $roduced "# $assing ammonia gas t/roug/ @0% sul$/uric acid $laced in lead lines 5ats at a"out @0G2 t/e cr#stals of ammonium sul$/ate se$arate out on cooling )*,* + *S, ()*!S, + *, -
Manufacture
rom by-product
Hanufacture of "#-$roduct ammonium sul$/ate ma# "e carried out "# $assing cleaned co!e e"en gases into an absorption column& counter current to a re-circulating stream of
saturated solution of ammonium sul$/ate A #$-#% sulphuric acid is now introduced into t/e stream at anot/er $oint 4/e neutralisation takes $lace and t/e effluent solution containing ammonium sul$/ate is $assed to a crystalliser & w/ere cr#stals of ammonium sul$/ate se$arate out on cooling 4/e cr#stals are se$arated eit/er "# filtering or "# centrifuging and t/en dried 4/e mot/er li7uor o5erflowing from t/e cr#stalliser is acidified and rec#cled to t/e a"sor"er >n an old saturation process ammonium sul$/ate is $roduced "# $assing coke o5en gas and sul$/uric acid into a 5at containing a saturated solution of ammonium sul$/ate and t/en setting out t/e cr#stal Synthetic Manufacture& Ammonium sul$/ate made 'ith manufactured ammonia is
called synthetic ammonium sul$/ate Bot/ saturator(s and crystallizers are also em$lo#ed in t/e s#nt/etic manufacture of ammonium sul$/ate 4/e /eat of reaction of an/#drous ammonia and concentrated sul$/uric acid o"tained "# contact $rocess is 5er# /ig/ *ence water
e5a$orated from t/e cr#stallier must "e returned eit/er "# means of a condenser or "# addition of water Sulphuric acid ma# also "e o"tained as a "#-$roduct from alco/ol manufacture& nitrating
$rocess& alk#lation in $etroleum refining and "enene $roduction 4/e acid o"tained "# suc/ $rocesses is called s$ent acid and contains a large num"er of im$urities Ammonium sul$/ate is dried t/roug/outl# to $re5ent caking ree sul$/uric acid is remo5ed eit/er "# was/ing on a centrifuge or filter or "# neutralising wit/ weak ammonia solution
"anufacture
4/e $rinci$al met/od for t/e $roduction of ammonium sulfat /as long "een "# t/e reaction of "#-$roduct ammonia from coke o5en wit/ sulfuric acid Because of t/e demand for
ammonium sulfate as fertilier ingredient& and t/e limitations in su$$l# from t/e a"o5e sources & additional amounts /a5e "een increase igl# $roduced "# t/e reaction of s#nt/etic and sulfuric acid #rom Synthetic ammonia and Sulfur Acid
>n t/e $ast ten #ears& increasing amounts of /ig/t-grade ammonium sulfat /a5e "een $roduced directl# from s#nt/etic ammonia and concentrated sulfur acid 4/e $rocess is essentiall# t/e same as t/e one descri"ed $re5iousl# & using coal gas as one te raw materials 4/e actual $rocess details 5ar# among different manufacturers ,ne $lant $roduces a /ig/-grade ammonium sulfate as follow : An/#drous ammonia is dissol5ed in water and $um$ed as an 18 to 8 $er cent solution to a reactor w/ere it meets a stream of sulfuric acid 4/e solution of ammonium sulfat (maintained at 3 / ! t/at form is $um$ed into dou"le-effect cr#stalliiers *ere t/e water is e5a$orated under 5accum lea5ing a metasta"le& su$ersaturated solution& w/ic/ readil# cr#stallier 4/e cr#stals grow in sie until t/e# are /ea5# enoug/ to settle to t/e "ottom of t/e cr#stallier A slurr#& containing to @0 $er cent "# 5olume of cr#srals& is disc/arged into automatic centrifuges 4/e cr#stals& o"tained in $racticall# t/eoretical #ield& are $ackaged in multiwall $a$er "ags 4/e mot/er li7uor from t/e centrifuges is returned to t/e cr#stallier
