CA2090649C

CA2090649C - A method for the disposal of used ion-exchangers

Info

Publication number: CA2090649C
Application number: CA002090649A
Authority: CA
Inventors: Hasso Von Blucher; Ernest De Ruiter
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-02-28
Filing date: 1993-03-01
Publication date: 1999-02-02
Anticipated expiration: 2013-03-01
Also published as: DE4304026A1; ITMI930386A1; JP2626956B2; GB2265143A; FR2687941A1; KR0125587B1; KR930017632A; CA2090649A1; GB2265143B; ITMI930386A0; IT1264353B1; GB9303956D0; JPH0692615A; FR2687941B1; DE4304026B4

Abstract

The present invention relates to a method for the disposal of used granular organic ion-exchanges. The method comprises carbonizing the ion-exchanges in a substantially inert atmosphere at temperatures of 300°C to 900°C. The ion exchanges are thereafter actuated in an oxidizing atmosphere to convert the ion exchanges into activated carbon spherulets.

Description

'~
A METHOD FOR THE DISPOSAL OF USED ION-EXCHANGERS

SPECIFICATION

The invention relates to a method for the disposal of used up synthetic resin ion-exchangers which mostly occur in the grain form.

Synthetic resin ion-exchangers are porous polymers having numerous chemical groups with exchangeable ions. In general, they consist of a copolymer framework of styrene and divinylbenzene or styrene and acrylic acid, said framework carrying acid groups, in particular sulfonic acid groups, for cation-exchangers and basic groups (amines) for anion-exchangers. Organic ion-exchangers of the kind having a polymer resin matrix selected from the group consisting mainly of polystyrene resins, polyacrylic resins, polyalkyl amine resins or phenol-formaldehyde resins, which may be present as cation- or anion-exchange resins, depending on their functional groups, and as adsorber resins are described in Ullmann's Encyclopedia of Industrial Chemistry, Fifth Edition, Volume A 14, VCH-Verlagsgesellschaft mbH, Weinheim, Germany 1989 in the chapter "Ion Exchangers", in particular on pages 394 - 398, and are commercially available under the trade names Lewatit*, Dowex*, Kasatel*, Diaion*, Relite*, Purolite*, Amberlite*, Duolite*, Imac*, Ionac*, Wofatit*. Numerous applications of the ion-exchange resins are also described on pages 399-448 of the cited chapter.

The main purpose of using ion-exchangers is the exchange of undesirable ions present in water for less noxious ions, and the complete removal of ions. If the ions that produce hardness - basically Ca2+ and Mg2+ - are exchanged for Na+
ions, "hard~ water * Trade-Marks .,.=
~ "

beco~es "soft" ~ter. If ~a~i~ns ~n~ anions are r~
m~ved, one o~tains deminçr~ ed water. Soft ~ter is ne~essary, for ex~mple i~ ~he texkile indus~ry, ~hd deminerali~ed wat~r in the s~eam gener~tion, in partiGI]lar in high-pressure boilers.

In general, ion-~xchan~ers become ineffective hy ob~
~truc~ion, i.e. ~heir pores get blo~ked by suspend~d p~rticles or inorganic residues~ su~h ~s iron compouhds .
The latter a~e re~ularly flu~hed out, ~t wit~ time, more pores heco~e progress~vely blo~ked and fin~lly ~he ~ed has to be replaced. At ~his point, the problem of disposal arises. As long as no ions that polu~
the environment are present, ~he used up ion-~xchan-gers Gan ~e disposed of in waste dumps.

Ina~ive gxanulous organi~ ioh-exc~ange~ resins ~re con~aminat~d with larg~ amoun~s of inorg~nic or orga-~ f~reign ma~t~r, su~h as sus~ended parti~les of ~11 kinds, slud~e, ~icroorganisms ~ ~lg2e and vaxious ca-tions, e.q. sodium, pot~s~ium, iron, and ~alci~m ions The a~ount of these impurlties is usu~lly up to ~ y weight, ~ased on the dry su~stan~e The granular ion-ex~h~nge re~ins ~o be disposed ~f have in ~ost Gas~s a ~a~er ~onte~ which may amount to up to S0~ by weight.

Sub ject ma~teL of the inv ntion is a me~hod for the dispos~l o~ used up granular or~ant c ion-exchangexs of ~h~ afore~entione~ kind ~o~prising c~r~onizing 1~ ~re-dominantly inert a~mosphere at temper~ture$ of ~rom 300~~ t~ gO~~~ ~nd subseq~entl~ acti~ating in ~n oxi.c~
~in~ a~mosphere~ t~s co~ve~ting said ~ exc~an~c~rs in~o acti~ted car~on spherul~ts.

-It is known in the ar~ to convext specifically d~fined poly~lfon~ted ~a~roporous ~ross-linked vinyl aromatic poly~ers into carbonaceous adsorber par~i~les by ~e~tinq to ~emperatures of up to 1200~ 5~PS 4,9$7,897)~ The ul~onic a~id groups are xeleased during pyrolysis, ra~
di~al sites are genexated whi~h le~d to str~ngly cross-link~d stru~tures that ~re not meltable and c~ontain little volatile ~arbo~.

Howe~er, i~ ~s surprisin~ that hi~h qualit~ a~rasion-pro~f aGtiv~ted ~arbo~ ~herule~s c~n be produ~ed also from strongly cont~minat~d ~sed up synth~ti~ resin ion~
exchan~e~s ~y pyrolysis and ~h~t the various foreign s~bstan~es do not impair the quality and st~bility of ~e adsorbe~ Surpri~inqly enough, th~ macro- ~nd m~-sopore struc~ure of ~he feed~ock is m~intained d~rin~
the disi~tegra~ion of the impurities ~nd ~he c~rboni-zation. The accummul~ed org~nic and biolo~ical pro-duc~s are de~troyed or escape wi~hou~ ~orming ~ny pro-nounced ~ar~on residues, in parti~ular if the ca~bo-nlzation is ~ondu~ted in weakly oxidiziny atmosphere~

In the used up cation-exçh~nger xesins r the ca~ion~
are usually ~onded to sulfonic ~cid groups ~d a~e su~stantially con~erted into sulfates at temperatures ~f up to 40~ t higher ~emperatures, they are re-duced by carbon r resulting in con~ider~ble amoUFIts of s~lfld~. It is, therefore, advantageous to firs~
convert catio~-exchan~er resi~s into th~ ~ ~orm prior to c~r~onization. This is prefer~bly done L~y washing the still moist materi~l with an acid~ i e. prior ~o dryin~.

20906~9 -- s ~

In order ~ rem~e the wa~er con~ent, whi~h as ~lready ~en~ione~ ~y ~moun~ to up to ~0~ o~ the ~ranul~r org~-n~ ion-~xcha~ge resin, i~ is recommend~d to dry the used up granular xesin to ~ disposed of, preferably in a rot~ry drier or in a fluidized bed. Prio~ to ining the softening point and usually after dry-ing, the syn~h~tic resin ion-ex~han~ers ~re prefer~ly powdered with an iner~ inorg~ic powde~, preferably carbon powder, to prev~nt agglomeration and ~o main-t~in the gran~l~r structure during the entire treat-ment .

~p to d te~peratur~ of 400~C, pre~erably ~p to about 300~ to 350~C, the iner~ ~tmosphexe of the carb~ni~~-~ion step ~n co~t~in 0.2 ~o ~ Yolume~ oxygen. The oxygen content is prefex~bly controlled by the addi ~ tion of air~ This preoxid~tion is ~e~ommended not only in ~iew of the des~ruction of the or~nic imp~ri~ie~, bu~ also, t~gether with the powdering and/or slow rise in temper~ture, i~ view of reduction of vol~tile c~r-b~n by oxygen ~ridg~s ~nd r~di~l sites, and ( ih view of) preventing meltin~ or sticking toge~h~r. In par-~icul~r, ~he preoxidation i5 ~ery l~port~nt when he resins do no~ ~ontain sulfonic acid grGups, e.g.
anion-ex~han~ex resins or ~dsorber resins. It iS re-~ommended ~o pro~ess ~h~se resin types ~ogether with ~tion-exch~nger resins co~ ining sulfonic ~id groups.

Minor amounts of ç~tions, su~h ~s alkal7 me~ nd ~1-~aline e~r~h me~al ions r ~le~ted f~om the group ~o~-sistin~ o~ sodium, pot~ssium et~. ur cal~um, ~hich were alre~dy con~erted into sulf2~es ~t t~le ~in~ing of the- pyrolysis, dcl not ~istur~ ~he ~ar~oni~a~l~n and ~ctivati~n, s~-~prisirlgly ~nQu~h, they ev~n pr~mote the ac~ tiQn step.

_ ~;

The activation o~ ~he ~rbonized material follo~s upon ~h~ c~r~onization a~ about 700~. Analogo~s to t~e car~oni~tion, i~ eah be conducted in a rotary drier or e~en better in a f luidized ~ed . To ~ctivate the materi~l, steam and/or ~arbon dioxide is ~dded in ~n ~mo~nt of 3 to 50, preferably 3 ~o 15 ~olume%, to the su~s~antially inert atmosphere. The ac~ivation tem-per~ture can be up to 900 ~C . ~o save energy, $he a~-tivation ~an be ~ondu~ed in the same app~ratus ~f~er the car~onization~ Howe~er, it mi~t be advantageous for spe~ific ~echnical and pro~dural ~easons t~ con-du~t ~he ~tivati~n in ~n independ~nt separate step, ~ll the more sin~e the ~arbonizati~n up to ~emperatures of a~out 5Q0~~ already entail~ a consider~ble ~hrinkage and a wei~ht loss of ~he feedstock of from ~0 to ~0~.
The ~r~on ~anten~ of the a~lvated ~rbon spherule~s after ac~ivation is more than 90~ by weiqht, Example 1:
1 kg of an m~cxoporous ion-exchAnger consisting mainly of ~yre~e ahd divinylbenzene~ which ~s present ih the H form ~nd was ~sed in ~he synthesls of f~el addi~ives (MTBE~ an~ had hec~me inactive, was ~rie~ in ~ r~ta~y drier at 110~~. Th~ loss in weigh~, c~used by vaporiza-tion of hydroca~bons and so~e moisture, was approxi~tel~
13%. T~ere~fter~ it w~ heated up to 30~~~ in an atmos-phere consis~ing of BQ~ inert ~as and 15~ ~ir and m~
~ined th~rein f~r on~ hour. The ~in in weight w~s a~out ~. Wher~p~n ~he tempe~ture w~ r~ised to 700~C
in inert ~tmosph~re with~n 3 hour~. 5~ ste~m were added in the r~n~e of 700~ to 900~~. The temperature rise from 700~ to ~0~¢ lasted for ~hirt~ ~inute~, the ~00~~ were ~a~hed in ~en fur~her mi~ut~s~

The y~eld w~s ~ b, b~ed on the feeds~ock. An agglorn~-ration of the spherule~ did not occux at any time.
A shrin}~ge of d}~met~r of from approximately ~ . 8 mm ~o O . ~ to O ~ 7 nnm, was o~ser~ed. The app~rent densi~y cf th~ spheru1et~ was l . 08 ~ m3 ~t a po~e volume of more th~n 0.9 ~ g, of which 0~55 mll~ w~re micropo~es~
A spe~ sur~ace of 10~ Itl2J~ was determined };~y ~he BET me~h~d~ ~ O . 5~ sphexul et could be loaded p~ncti-form with 3 0 0 ~ without bre~kage .

m~l~ ~ 2 -1 3cg of a gel-~ype cation-exchanqe~ ~hi~h had been us~d for ~he so~nin~ ~f wate~ and had no suffi~ient ac~ivi~y w~s ~onvex~ed into ~he H+ form l~y means of a hydrochlori~ a~i d solu~ion. Af~er superficial air-dryin~, the mois~uxe w~s about 50~. Af~er drying a~
1104C, oxidatio~ was carried ou~ in air ~t 300~C fo~
6 h~urs. The pro~edure of E~mple 1 was ~ereafter ~pli~d. The yield was 31~, based on the feeds~oc~.
~he spherulets were partly ~gglomerat~d.

ExaInpl~ 3:
The proçess of ~xa~nple ~ was applied in ~he s~me manner arld with the same feeds~ock, ~owever, a~ter oxida~iorl at ~00~C, powdering was ~onducetd with 5% carbor~ powder ~nd the temper~tUL~ was r~ised to 700 ~C with~n 6 hours .
The agglomer~tion of ~h~ spherulets and the fo~ ti on of ~ ~listered stru~tur~ could ~hus be preven~ed. ~he in~er surface of the ob~ined a~ivated ~a~ on p~xti~les 2mounted to ~pproa~ima~el~r lOQOm~J~r ~B;E~T) ~nd ~he yield w~,s 40~; b~sed on 1~hA~ feedstock. The ~ver~ge ~urst~ng pressur~ was 2~0 g at ~ di~e~er of O . 5 mm.

~ 2090649 Also macropor~us ~ds~r~er resins ~on~istin~ ~ainly of ~ di~inyl~enzenP-~opolymer w~re pro~ssed in the $ame manner to yi~ld ac~i~ated c~rbon, said resins had been ~lready used up and 5~ con~ained adsor~ed organic su~s~ances. Sin~e these prod~cts do not c~nt~in any sulfoni~ acid g~oups t a preoxidation is particul~rly iml?ort~nt .

Claims

1. A method for treating used granular organic ion-exchangers comprising the steps of drying the used granular organic ion exchangers and subsequently heating the granular ion exchangers in an inert atmosphere at temperatures in the range of 300°C to 900°C to carbonize the granular ion exchangers, adjusting the temperature of the carbonized granular ion exchangers to a temperature below 400°C and adding to an inert atmosphere in contact with the carbonized granular ion exchangers 0.2 to 4% by volume of oxygen, thereafter activating the carbonized granular ion exchangers by heating thereof to a temperature above 700°C in an inert atmosphere to which steam and/or carbon dioxide has been added in an amount of 3 to 50% by volume to change the granular ion exchangers into activated carbon spherulets.

2. A method as claimed in claim 1 wherein said step of adjusting the temperature of the carbonized granular ion exchangers adjusts the temperature to be in the range of 300°C to 350°C.

3. A method as claimed in claim 1 or claim 2 wherein the amount of steam and/or carbon dioxide added to the inert atmosphere is in the range of 3 to 15% by volume.

4. A method as claimed in claim 1, 2 or 3 wherein said used granular ion exchangers are cation exchangers.

5. A method as claimed in claim 4 wherein said cation exchangers are made of sulfonated styrene-divinylbenzene copolymers or styrene-acrylic acid copolymers.

6. A method as defined in claim 4 or 5, wherein the cation-exchangers are in the H+ form.

7. A method as claimed in claim 1, 2 or 3 wherein said used granular ion exchangers are anion-exchanger resins.

8. A method as claimed in claim 7 wherein said anion-exchanger resins are made of polystyrene resins or polyacrylic resins with tertiary or quaternary amine groups.

9. A method as claimed in claim 1, 2 or 3 wherein said used granular ion exchangers include granular organic adsorber resins.

10. A method as claimed in claim 1, 2 or 3 wherein the step to activate the carbonized granular ion exchangers is an independent step in the method.

11. A method as claimed in claim 7, 8 or 9 wherein the granular ion-exchanger resins are mixed with an inert powder prior to attaining the softening point of the ion exchanger resins.

12. A method as claimed in claim 11 wherein the inert powder is powdered carbon.

13. A method as claimed in claim 1, 2 or 3 wherein said method uses a fluidized bed or in a rotary drier for carrying out the step of the method.