CA2104601A1

CA2104601A1 - Methods for processing battery waste and other lead-contaminated materials

Info

Publication number: CA2104601A1
Application number: CA 2104601
Authority: CA
Inventors: Alistair H. Montgomery; Wolfram H. Kube
Original assignee: Individual
Current assignee: NL Industries Inc
Priority date: 1991-02-22
Filing date: 1992-02-21
Publication date: 1992-08-23
Also published as: EP0572552A1; AU1460492A; US5173277A; EP0572552A4; WO1992014797A1

Abstract

The present invention is directed to improved methods for processing battery wastes, battery casing debris and other lead contaminated materials. In another aspect of the present invention ebonite and other hard surface materials to which are adhered lead contaminants are mixed with water and abraded in a high energy scrubber to remove the adhered contaminants prior to separation of the cleaned ebonite from solution. In another aspect of the present invention, plastic and other soft materials contaminated with lead are mixed with a solution to dissolve lead contaminants.
Separation of particulates produces clean scrap or recyclable plastic while carbonation of the wash water permits recovery of lead carbonate. Finally, the present invention provides methods for controlling dust contamination prior to and during processing by spraying the fine raw materials with an aqueous solution of a wetting agent.

Description

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lMPROVED MErHODS FO~ PROCESS~G BA~TERY WASrE

~a~nd Qf.~ln~Qn S Tbe pr~nt in~ don gally re~a~ to mal~ for rcmo~ng l~d f~om lead-c~ ~ast~ ~nd ~cular~y ~om us~ sto~ge ba~ics and ba~ay debris piles.
~lor~ spedfically, the ps~t inve~tion t~ di~ oa p~urality of cn~DDm~tal~y ~aYo~ble 3~hod~ ux:hl to a~ ol dusX and ~mcr~ on and ~ ~e~ thc removod kad, t4gc~h~ with clean ~/re~cl~ble e~nite, hi~d n~s srld pl~ mc~ods of ~ p~ ve~on employ bo~ hydromechania~ on proc~ and ch~nical x~ioa ~ u~ng mo~ en~i~tally 2ccq~blc cbemicals t~an those employe~
in ~e prior ~n.

Lcad ~cid ~tora~c batluioe ~se compnsed of a plusa~ity of Icad pla~s imme~sed in a ~S su~ic ac:id d~lyte 301udon con~iDed w~in a non coaductivc c;~sc, typically cornprisod of pla3~c or ~ n~vba, c.g., ebn~lte. Pl~tcs of opposite polarity ue i~sulated from one another by rnea~s of porws ~ ors. El~hcr~;al power is dr~wn *om thc plates through conductlvo lead a11oys ~orming t~rrr~s and joi~d to thc pla~es. The chcmically ;Icdva ~aterials wc spo~ge lead at the cathodc ant le:~d dio~ide at the anod~. When thcse ~ive matcrials are dect~ically c~ ~n t~bc prcsenx of sulfi~ic acid, an o~idation-roduc~on sea~tion c~s dectrochemical cnergy ar~d ConY~:rtS thc lead mataials ~o insoluble h:ad s~fatc. Watcr, producod as a by~pr~duc~ of thc seac~on, reduccs the conccntra~lon oi sulfu~ic ~id. As thc lead i~ convcned ~ lcad suLFa~e and the concaltration of clectrolyte rsduc~d, Ihe bat~y out~ut wcakcns and Ule used bal~y is scsapped.
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~s re~ult of s~e a~id~ ~on f~osn ~hich elecsricity is produce~, ~ ~pped ba~i~, ~ ~klit~on ~D W~ining le~d u~d ~d dio~idc, nl~o a1ntain ~nif~nt quantities of Icad sulfate in a weak sutfuric acid solu~ion. Scrap ~alteries havc geneTally b~n cons~dcred va~uablc only for thdr lead con~enn Accordingly, many patents are dir~ctcd ~o m~thods for rccovcrin~ thc lcad from sc~p balteries. 3:or e~an~ple, sec U.S. Patcnts Nos.
4,118,219, 3,689,253, 3,393,876 and 3,300,043 which disclose various smelting and . chcmi~ mcthods for recov~ring lead from sclap battuies.
Sepasat~ and ap2rt from Icad recovery are the emiTonmental problcms resulting from used or sc~pped b~ncries, scrap lead and other materials contaminated by lead. As en~ronmentaJ knowlcdge and s~andards haYe increascd, she ne~d So proccss scrap b3ttuie5 and other lead~contanLinated mate~ls has incr~ased. lltese enviTnnmcntal problcms havc 10 incr~asin~ly become imponant in oonnection with the clean-up of manufacttl~ing, slorage and sp sites cont3minate~1 by lead. Thc clean up and rcnloval of lead cont3mination from such s,it s and the materials ~red th~re withou~ producin~ sxondary contarnination through wind-b10wn, lead~taminatod dus~ or discharge of watcr contamir~d with lead or other ~hemicals has ta~cn on a new impot~ance.
Of particular conoern is the desire ~o extract the c~ntaminating leat in a recoverable ~nn whlle producing scrap rnatc~al ha~lng an acccp~abl~ lead contcnt and, particularly, an acceptable ext~actable or leachablc lead content which might perrnit the recovered ma~crials to be rccycled. Aceordingly, a ne~d has developeo fior methods for e~t~acting lead contaminants from the plastic ~nd ebonite portions of uscJ storaEe batteries. Methods to 20 produc~ scrsp matcrials, e.g., ebonitc and plastics, mee~ing more stnngent luchable lead conc~trations, whether mcrely fior scrap or for recycle, have insensified.
The me~hods of she presenl invcntion which provide thc ability ~o recover rccyclablc matcrials during the ctean~up operasions and thus to minimi~e disposal and storage of~cr '. ~ `'1 ~ignificant advantagcs over he prior an. The prcsent invention provides mcthods capable o~

~3~ ,~ ~ U'l~01 ~ducing ~he Icachabie lead cont~t of sclap ebonite and plastic below S ppm whcn dctcrrnined by the Ex~ction Procedure Toxicity t~st tEPTox). The EPTox t~t pr~urc is s~t fonh at EPA Mc~hod 1310. Thc present invention offer, melhods for meaing e~cn morc rigorous s~ndards, c.g., leachabl~ lead dc~nninc~ by the Toxicity Charactens~c Lcachlng Procedure 5_ ~1I~P)t which may be applicd in thc future, Thc TCLF~ t~st pr~xdure (EP'A Method 13 11 ) is set forth at 40 C.P.R. Part ~6I, Appendix 11.
Ac~rdingly, thcpre~cnt i~vend~n has pt~-~ided metho~s fior m~dng the long felt bu~
~mfu}filled neod for cmironmentally sa~e methods of proccssing lead~ont;aminatcd materials and riucing the lcad and leachable l ad ~on~nt o} va~ious mstenaJs, e.g., ~crap plastics, 10 e~onile, other hard rub~rs ~nd o~her Icad-con~aminatod mat~rials, to providc clcan scrap or recyclable mat4s3al5.

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4 ~1~46 - Sulnmarv of ~he Invcntion Thc present invcn~ion is directefl to simple and environmcntally prcfcrred methods for processing Icad oontaminated matcrials to reduce the lead and Icachable lead cont~ thereof and lo se~a~ately rcmovc therefrom lcad and scsaplrecyclable ebonite and pl . ~tic rnat~rials.
~_~e pr~sent inverltion includcs me~hods for improving d~Jst control, for hydnomech~nical sepaIation and cleaning and for chemical sepa~tion cmploying environmentally favored ~ge~ts. The me~hods of the pr~sent inven~ion are particu3arly llseful in the proccssing of use~ s~orage batt,ies and battcry dcbris pilcs including ~ariouC plastic, ~onite ~nd otber hard ~ubber matcrials contaminaled with lead and lead compounds.
1~ . In th~. methcd~ of Ihe present u~vention Ihe le~d ~Con~minat nat~nals to bC proccss~i are initially crushed or ~round. l~esc matcrisls generally includc plas~i~s, cbonite and other hard nJbbers in addition to lead and various lead compounds. The crushed or ground materials ar~ sized by convcnti~nal mcthods to pro~ide raw, contaminated matcrials which will pas.s through a 4 inch scre~n. This rnaterial is conveye~ to a t~ommel scrubber where 15 thc Icad fincs arc washed from thc la~,er casing fragmcnts with watcr. On discharge from thc trommcl, thc rna~erial is sizc~ using scrxns ~o betwecn about 10 mcsh and about l.S
inches for funher proccssing. Oversize materiaLs are retumcd to ~he crushcr. The undersi2c material consists of lead concentra~e ~rorn which thc Icad is easily r~movcd by convcntional rnethods The materials which have ~een sizcd for furthcr proccssing comprise eboni~e, hard 20 rubbers and plastics witn a roduced l~ad con~en~. It has becn found that malsrials betwe~:n aboul 10 mcsh snd about 1.5 inches improve the handling and yield, particularly Or clcan, scr~p or recyclable ebonite snd plastic rnalerials, whilc reducing fines which mus: be stabili~ed for disposal.

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After 5epa~ation of ~hc trommcl scrubbcr wash solu ion containing the Icad fincs comprising most of Lhe contaminating lead, lhc remaining (10 mesh lo 1.5 inchcs) solid matcrials compnse mostly plastics, ebonilc and o!her hard rubbers still contaminated wilh lcad and lead compounds. ~ mi~cture of this contaminaled material comprising prcfcrably ~om about 30 to about 80 pcrcenl-by-wcigh~ solids in water is vigorously mi~ed in a high encrgy S ~ bcr such 85 a~ itic~n scrubbu. Hi8h encrgy scr~bbing abradcs Lhc lead contaminanLs fr~m the surfac: of tho ebonite, hard rubbcrs and otha hard surfacc, polymenc rndtcrials, ~he clcaned ebo~it and other harq~s~lrface matcrials are uhen scpara~ ~rom the wash liquid by conv~ntional ~c~ecnin~ oataLion ~par~n m~lhods.
Anothcr fea~: of the presant invcntion are mc~ods ~D ~ducc thc lead and Icac~able 10 lesd OODWlt of sc~ap/~cyclable plastics and other soft polymaic matuials. Yrhile athition scrubbing in wa~er rnoves the ~dhenxl lead contamin~nts from ebonites and other hard rubbs mere attrition scrubbing i5 insufficient to clc~n so~cr rnaterials e.g. the v~nous pl~stics oflen u~ed in the construction of balteries. rbe present inven~ion offers methods capable of reducing the lead and leachab]e lead contcn~ of Ihese soft rna~ls. The lead-15 contamlnated plasdcs and oth~ soft rnaterials are cont~ac~ed with an agueous sotution havinga pH gr~aler than 7 prefaably gn a~ Ihan 10 lo dissolve the lead contarninants ~hercfrom.
P~fcrred solutions ase aqucous allc~li atltatine earlh or amrnonium hydroxidc solutions in concentra~ions of from about 1.0 lo about 10 pelcenl-by-weighl of the chosen caustic compound. ~os~ prcfertod is an ~qucous solution comprising about 2 per~nt-by-w~i~h~
20 soJium hydroxide. The contamina~c~ pl8stics and other soft mattrials conveniently arc mixcd with the aqueous causlic solulion in the gntition scrubber. Ttl4 clcaned plastic is rccovered using convcntional screcning and floa~lion scparation methods. The dissolvcd l~ad is rocovercd as Icad carbonatc by oonventional ca~ona~ion of uhe filtJale.
,..j Wind blown contsmination of off-site s~ils by lcad fines and lead-containin~ tusts is -6- ~lUll601 a significant problem. Another featute of Ihe proccsscs of the present invention are me~hods for reducing contamin~tion from lead fincs and lead-containing dusts dispsed Srom ~hc raw materials prior to wct processing. It has been ~ound that such contamination is prcvented or at lea~ ~ratly rcdu~d by the application of a wctting agent to the piles of excavated S - ~Is and to the grizly, crushe~, feeder and trommcl scrubbcr. F~vorable rcsults have been achieve~ by sp;aying a dilute, aqueous solution of an inorganic wetting agent ovcr the crushed or ground s~w roaterials. ~Prcferred wctting agcnts ioclude alkali, alkalinc ea~h and ammonium car'oon~tes, bic~ubonates and sesquiG~onat~s. The most prcfcrrcd solution is an squeoUs soludDn cotnpl sing about 2 perænt-by-w~ight sodium car~onate or sesquicas~ona~e.
10 ~n ~ddi~on t~ controlling dùst and ~ind blown ]ead c~ntasnina~i~n, applicatiDn of a dilute solutioo of such wetting agents impro~cs Ute proeessing of rnaterials in uhe t~ommel serubbcr ~nd m~y iolprC~Ye scparatlon of ]ead nnes, thus belping to reouce tbe lead content of the remaining plastics, 'ebonite r~nd h~rd rubbers prior to funher pr~ccssing.
Tbe pro~csses of tbe present invendon provide various methods for reducing the lead lS and le~chable lead contcnt of Icad~ontamin~te~ mat~rlais, particularly the ebonites, hard rubbers ar3d plastics associated with uscc sto~,e batteries. Wbiîc producing clcaned maleriais of aoccptablc quality, t~3e methods of t~c prcsent invention employ hydromechanical and chcmical scpar~tion methods dxm~d environment~lly favorable relatjvc to thosc of ~he prior art, Purlher, tho methods of the presenl invcntion minimize further envjronmental 20 conlamislation by p~vidin~ improved dusl control ~nd by ra:ycllng uash solutJons. Tbesc and othcr mu~torious features and advantages of the prescnt inyes~tion will be more fully apprecialod from thc followin~ detaiiod descnption and claims.

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~ 7 -- Bnef l:)~Dtion of thc~ )in~ 1 . Othcr feature~ and int~ndcd advan~ages of thc prcscnl invention will bc more readily apparent by the references to ~hc follo~4ing dctail~ dcscnption in conncction wi~h ~'ne sccompanying drawings, wher~in: . .
'.! 5 Fig. 1 is a ~ch¢matic re~re~E~tion o~ thciniLial pordon of the proc~ of Ihe pr~nt in~a~tian illus~ting dust oontrol with an aqueous soludon of a wetting a~ent, the sizing of U~e fee~ rnaterial and ~he initial scpa~don of lead fines following mixing in a ~ommcl ~ubb~s:
Fig. 2 is ~ schema~c rcpres0tation of lhe middle portion of the proccsscs of thc~0 prescnt invendon illus~ratin~ an a~i~on scrubber as~d to ab~asively and hydromechanical]y clcan adhenng lead ContaminanLs from e~onite, ha~d rubbers and other low density, hard ~rface rnatcrials; and Fig. 3 is a schcmatic represent~, ion of thc lat~r portion of thc prttcesses of the present inveDtion iillustrating the cleaning of la~d contamiDatet p~stic~ by mixing in an attrition scnJbber with ~n aqueous caustic soludon, rocovcry as 1~d car'oo~a~ of the Icad removet in the clcaning p~ocss and ~ecycle of Ihe wa~h solution for dl!st con~ol.
Whilo the invention will ~oe tescribed in coM~ion with the presently preferred cm~odimen~ wil] b~ understood tha~ it Is not intendcd to llm~t the invention to t~s ea~bodimcn~. ~)D the con~ry, it i3 intended lo ~ove~ a~l ~lternatives, modifications and ~0 iui~alcnls as may l~c i~cluded in the Spiril of the Invention as defined in thc appcndcd claims.

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I2~ailc~D~s~on oflhe Prererre~ Embodiment In the methods of tne prescnt invcn~ion lead~ontamina~ed maleria]S, particularly vaste ba~teries and battery casing dcbris are pr~ess~d to reduce the lead and lcachablc lead content thcreof. The pr~ccsses of the p~nt inven~ion offer methods for wntrolling lead dust S ~ sions and t`or reducing the ~ead and ~eachable l~d content of plastics, e~onites and oLner l~rd rubbers lo accep~ble en~vironmerltal levels ~hile providing melhods for recovering Lhc scmoved lead.
Thc meIh~. of She prescnt invention are employable with any lead~ontaminated ~te~ials. However, thcse rne~. haYe be~n par~cularly designed for use with waste 10 s~,e bsttcries, batt~ casing dcbn3 and o~hcr materials from 3ead~on~minatcd sites.
The Icad contaminan~ are generally pre~ent in the form of lead sulfate, l~d oxidcs, lead G~Onate and metallic lead.
l`ho wast~ battcrics, casi~g d~ris and o~her lead contaminated matcr~als are initially gtour,~d or crushcd to producc T3~W mateTia.ls of a dcsirab]c size for processing. 1~ has been 15 found that raw mat~rials which are t40 large are difficu1t t4 pl~;S, destTuctive of thc mi~ing apparatus and produ~o unsatisfac~oTy rcsults. On the other hand, rnatcTials which arc too small, i.e., include too rnany fines, pr,csent olher processing dimcultics, parliculaT]y ;ncreased dust arld unr,ecyclable materials which musl~be slabilizecl for dispos~l, The m~thods of thc prcsat in\~ention will first be descTibcd with respect ~o Fig. 1.
~0 Thc ground or crushed lead-contaminalod malenals, e.g., wastc batterics, battery casing debris and o~her e~tcavalod fe~d matelia!s, are delivered to gr~ly screcn ~0 for si~in~. Thosc materials which do not pass through thc 4 inch screen or gri7~1y 10 arc transported via line I2 to cn~sher 170 for appropriale gnnding or crushing. Thc malerials passing l,hrough gri221y " 1 10 move along path 14 to iecder scrcen 16. Maler;als which pass through the 4 inch scre~n :: ' `

~1U'160~
o~ fca~cr 16 aTe tJansportcd along line 18 lo ~rommel scrubber 20. In tromm~l scrubber 20 the materials are weuod and admi~ed with watcr or an aqueous solution. l~e avcrage r~sidence time in scrubber 20 is about 30 minutcs and can vaJy from about tcn minuteS lo an hour or more. Mixing typic~lly is pcrforJned at ambient p.~ssuse and tempcrat~c, i,~, about SOP to z~out 80F. No e~fon i5 rnade to con~l ~he tempcratare. The ~lurTy e~its trommcl scn~bb 20 through scr~n 22. Material which will not pass through this 1;5 inch screen is rct~ m~d via line 26 t~ cn~sher ~70 fivr ~urLher sizing. Malenal which p~ses Ihrough s~een 22 tS convcy~ a line 28 to s~cn ~0, a 10 mesh scpaIator. Scteens ~ and 30 3~e washed vrith wa~er or ~ctting ~oludon from lincs 24 and 32, rcspectively.
1~ Thc fine rnatcrial passlng ~ugh s~n 30 is less than a~ou~ 10 mesh This fine rnatcrial is conveyed Yia line 34 to conventiona~ scrcw classifier 36 whcre the lar~er, i e., ... .
greater than about 100 mcsh sands are ca~ied via line 38 for collxlion of a Icad fincs conc~ntsaIe. Most of the lead origiMîly contaminating thc raw materlals is removed at this st~p. Lead is r~coverable, generally by conv~nsional srnel~n~ and r~fining proccsscs, from IS this lead fincs product. The small materials, i.e., Icss than ~bout 100 mesh fincs, a~re conv~yed ~ia line 42 to ~nk 40 for ~ickcning. Tl~c very fine m~eri~ls are thickencd by scttling, preferably wi~h the ~dditional o~ a convcntional tloccu3ent, c.g., a polymcnc flocallcn~ such as Bet~ polymer l IS9. Il~e thickenod fincs ~re dcliverod from hnS: 40 to filter S0 via 1ine 46. The filter caluc 52 from fil~cr S0 is added ~o ~he lead fines product. The flltratc from filter S0 i~ returncd vi~ line 48 ~o Ihe Inpul ~o tank 40. Clarifiod aqueous solu~on f~om tank 40 is re~trne~ ~ia line 44 to screcns 22 and 30 for r~cycle or lo we~tin~
~olution tank 172.
It llas boen found tha~ con~nina~ion cf ~hc emironment by ~ind blDwn dus~ and fines ~; iJ psc~ented or a.t Icast grcatly reducod ~y Uhe appll~tion of a dilute ~queous solution of a : .

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wctting agent. The ~xcavat~d mat~r.ial maimainod in slDragc piles a~oul Ihc sitc should be so wctte~l. Weltin~ is achie~cd by sp~ying or misting the ~w maleria~S with a dilute aqueous solulion of a we~ting agent until visibly cs~ated and wetled. Further, it has bxn found bcneficial to spray or mist the ~vetting soh~tion onto the materisls ~n the gr;izz~y, c~usher, S fe~,d aDd trommel ~ubbes to minimuc dust and achie~e Dlaxitnum bcnefit. Contact of the raw m~tcrials with the dilL~ us solution of a we~ing a~ent pr.ior to sepa~ion ia bommel ~ubber 20 may also~improve r~mo~al of Icad cont~minants into the lead fincs pr~duc~ portion e~ ng the scsubber.
lbc wcsting SOJtltiOn i3 p~ed ~ld ~ in lank In. n~e solution is prcpared 10 using m~up or ~ocyclc ~$er delivered ~hrough line 44 for m~ing with a Wcttillg agcnt.
Additionally, ~e wash wat~r f~m the iina3 plastic cleanin~ pro~s p~oduoed at 168 (Fig. 3) '~ 1. .
may also be used fior r~-up. The w~ing solution is appli~d by oon~ tional sprayers or misters 174 to thc ~scava~ed feet n~terial, griz~ly 10, crush 1~0, f~des 16 and tsommel 20. While convcnd4~ul organic ~urfi~cnnts, e.~., dsrgents, r~y bc used as wetting agents, 15 thcy are not prcf~ed duc tO ft~l~8 ~istics and ~ desire to minimi~e the cnvlronmental impact of the wash soludons. Bccause of their compatibility with the remaining stcps of the p~cess and bocaus~ of lhe ability to nxycle process soludons.
inorganic wetting ~gen~ arc preferred. Recycle of these solutions significa~ntly reduces Lhc volume of waste ~vakr which mu~t ~e discharged off si~e and ther~by imp.ovcs the20 cn~ironmental s~tability of t~e pro~sses of ~he p~s~s invenù~n. Pref~rcd wettin~ agcnts includc thc ~l~li, alhline carth and ammonium cart~onatcs, bica~onales and scsquicart~ona~cs. Aqueous soludons compnsjng ~bout 0.5 pesccnt-by-wcig~ or morc wct~in~
~ent in water ~ave k~n found efftive. Beeau~e liltlc improvcmcs~t is obser~/cd a~
ConoentraLiions ~reatcr ~ bout 3 pera~t-by~wci~h~, psefcrred concentrations arc about I

iU~Ul to abou~ 3 percent by-weigh~. On the basis of fiJeld observauons, the most prefe~ed solution is prcsently believod ~o be an aquo~us solu~ion comprising about 2 percent by-s~eight so~ium uicarbo~ute.
The Improvunent in dust cootrol achi~ved by usin~ dilute solutions of ~n inorganic -S wet~ng ~ent wa8 dnon~ate~l by ~ simple esperimenl. Powdc~d ebonitc was pr~pare~ by grinding ~nd s~ing ~ e~onite sample IO less than aboul 65 me~h. Thc sizal samplc was dried and stored in ~ seaJed co~ltainer. Sodium carbonate solutions of ~ing concentra~ions (O.S, 1.0, 2.0, 3.0 and 6.0 pu~ -by-weight) werc preparcd by combining tilC appropnatc ~ght of sodium ~onate witb dchnized wa~r. Tests we~ conductecl with a s~lid:liquid ~o to p~dc a 20 p~t 501ids ~IU~. Tcs~s werc c~nducted in 400 ml gl~ss bcakess with a J~lagnetiC stil~ ~ct al a constant speod so pro~ide ~igorous stimng. Each sample was test~d by first placine 125 grams of the sodium rbonate test solution In the beakcr, adding the stirs~ng bar and ~iva~ng the sdr~er ~o thc prcde~ernuned spxd. l~rcnty-fiYe grams of drie~
~nd sizod, powese~ ebonito w~s w~ully placed on the surfax of the sdrnng solution. The IS timc from placi~ng the po~d~r d e~on{te on the solution until the ebonitc was completely dtawn into solution, i.e., complctoly wested, v~as meas~r~d, Deionizod wa~er wa~ run a~ a control. The rc~ulL~ are illus~a~ in ~ab1c ~.

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TAB~E 1 - ~ . - .
l 80diu~ C~rbon~te Concentrat~on Settling ~im~
: 25 (percont-by-weig~t) ~inutes) __ _ O ~ ' 19.~
0.5 7.5 . 1 0 3 0 3.o 2 .S
6.0 2 .S
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- 12 ~ 6 0 1 This test illush~s the remarkablc improvemer~ in wetting achievcd by using a dilulc a~ueous solution of an inorganic wetting agenL. This lest further illus~ates that llo significant improvement is achieve~ at conccntrations grcatcr than about 2 perc~nt-by weight.
ring now to Pi~. 2, ~e output frorn screen 30 comprising matcri21 from which - 5 mo~ ut not all the kad ~maminaLion h~ be~n removed and which has bæn size~ to buwoen a~out 10 mesh aJld abou~ 15 ir~ch is deJivercd via line 54 to hetvy media s~rator ~0 fot separation of metallic lead and oth heavy materials using magnetite delivcrcd via line 58. Make up ~a~r ~s delivere~ via lines ~6 to separator 60 and scre~n 62. Thc mat~s lea~ing beavy me~ia separator 60 a~ hrough sc~en 62 with thc oversized rnatcrials 0 ~CiDg ~emoYed by screcn 6~ and canied away via ~inc ~4. The fincs from the wash arc deli~eseci via line 66 to the lead fines product or to stabilization, dcpending on the Icad content. ~he remainin~ float ma~rials compris~ e~sentially the plastics, e. g, ~ polypropylcnc, polycthylene, PVC ard other relat*ely soh polymen~a~ion products, ~ogcther with low de;nsity, i~rd surfac4, hard polyme~stion produc~s, e.g., eboni~e and other hard rubbers.
15 Th~e mascnals are ddivcred via line 68 to atttition scrubber 70.
Bocauso attrition scrubbing abrades not only thc lead contsminants adhercd to the surfac~ of th¢ hard polymeric maleriais, but also a por~ion of the surfacc of those materials, si~e of the staning ms~erials, along wilh lhe scrubblng conditions, includin~ scrubbing speed arld rcsidence ~Imc in the scrubber, are ImporL~nt faetors. Psopcr sizing of t~lc materials, 20 p~nicularly the hard polymeric materials, hat bccn found lo bc panicularly important in raxlvy of improYed yields of recyclable eboni~e and o~her hard rubbcrs~ Minirnization of the ebonitc hnes which must bc slabilizcd for di~posal and ma~imiz.ation of cluni, ~cyclablc cboni~c Is important to the cconornics of these cleaning processcs~ ~n the p~st, attriLion ~cmbbers usod for processing other malerials geneRlly employed smaJler mat~rials, .,, ~

~ ~1U i6o1 i.e., ma~erials sized to be less ~han about 0.375 inch. ll has becn found in ~he present methods that those small s~rting maLerials yroduce an unacceptably low ratio of rccyclable scrap to fines which must be s~abilized for d;sposal. Use of larger materiaTs, preferably those as large as about I inch to about 1.5 inch increascs lhc ratio of recyclable cbonilc to fines.
5 - W~th materials sized to less than aboul 0.375 inch, ~hc ratio of recyclable ebonite to rmcs was about 1:1; with materials si~cd to less than about I inch, the ratio of recyclable ebonite to fines inct~ascd to about 4:1; and w.ith materials sized to less than about I .S inch, the ra~io of recyelable ebonit~ to fines was at ieas~ about S~
AttnLion serubber 70 provides a hi~h energy scrubber for vigorous scrubbing of the 10 rnaterials delivere~ via line 68 from heavy rnodia separator 60. Exemplary attrition scrubbers are manufactured by Denvcr Equipment Co. in various size5 and with various mixing powels.
Aurition scrubber 70 includes a plurality of agitators 12 turned by a plurality of mo~ors 7~.
In order to achieve s~igorous scrubbing it is been found desirable to ope ate a~tridon scNbber 70 at betwecn about 800 to about ]500 rpm. Makc up water is added to attrition scrubber l5 70 ViA line 76. While satisfactory results have been obtained with solid concentra~ions as high as about 80 percent-by-weight in water and as low as about 30 percent-by-weightj it has been found desirable to operale attrition scrubber 70 wi~h solu~ions comprising from about 60 to about 80 perccnt-by-weight solids in water. It is desirable lo mninLain a high conccn~radon of solids ~o iner~se ~he~ efficiency of the abrasive scrubbing. However, concentradons which 20 are too hlgh will slow or damage the scrubber. On ~he o~her hand, coneen~rations which are too low do not provide lhe rcquite~ abrasive contact. Surficient lead removal is obtained with residence times in a~tridon scrubber 70 as low as IS minutes. While residence limes may bc up to ~wo hours or morc, it has been ~ound desirable to maintain residence ~imes belween :~ ~ about 15 minutes and I hour, preferably a~ou~ 30 minutes. While the scrubbing lempera~ure .. . .

JUL-2a-1993 14:25 FROM 3ROWi`llNG. 8US~ RS TO 16a~443~136 P,e4 - 13 ~ 6 U 1 may range between the fræzing and boiling points of the scrubbing solution, i.c. wa~et~
sclubbing typically is performecl at ambient temperalure and pr~ure. 8ccausc heat is Rene~t~ by the vigorous scrubbing and abrasivc action and no cf}ort is madc lo control the ~emp~ature, tem~cr~sures gbovc ~bient are oommon in scrub~er 70.
Thc ~utput from at~;ition sc~ubber 70 is delive~d ~r.ia line 78 to scr~n 8~. Using make-up ~atc~ delivcrod f~m line ~2, the cl~n~ ebon;te and plastic mat~ials greau r than about 10 mcsh aro passe~ ~a li~e~g6 to conventional watcr sc~ator 100 whcnc Lhc plastics float hi8h~r ti an the e~onites and ~ readily s~ated and rnoved by convcntional mcans.
The clea~ e~onite is removed f~m water separator 100 v~ lino 104 whi~e thc plastic is removed ~ line 10~ hr further prooessing. Line 84 delivers the wash wat~r from scr~n 80, incluting thc lead contarninants ab~aded from the e~onite and the ha~i rubbers to tank 84 for thickening. Thtckening is achicwd by settling, pr~ferably with addition of a standard no~culcnt, e.g., a polymeric flocculent such as Betz po1ym 1154. ~e thickened sludge, including ab~ded ~cad contaminants, is conveyed via line 88 to filtcr 90 fr~m which ~he filter 15 cake 9~, containing the ab~aded lcad ccntaminants and cbonit~ fines is remo-ed ior stabilization Ihe filtratc from filter 90 is tecyclcd via linc g4 to thickening unk 84 ~ifled solution from tank 84 is delivcrcd via line 86 for recycle via inlcts ~6, 76 or 82 to, respcctively~ the heaYy media sepa~tor 60, attrition scrubbcr 70 or scrcen 80.
Thc plastic recovete~ at 102 aftcr attrition scn~bbing wilh wat r rcmains con~aminated 20 with lead, l~ is bclieved lhat attridon scrubbcr 70 is able to effec~i~ely clcan hard surfacc materials, e.g., ebonitc ar,d hard rubbcrs, bccause the contaminating lead which is adhcrcd to ant in the porous sur~acc thcteo~ is readily abraded by the ~dgorous admixing in the at~ition scrubbcr. On lhe olher hand, a~ ion scmbber 70 is unable lo runove suffiden~ lead!
contaminan~ from sof~ ma~erials, e.~., plastic5, ~hich are apparen~ly not readily abrad~d by ~UL 2~1. '93 15:32 713 266 5169 P~GE.004 4 6 ~ 1 the v;gorous scrubbing action. Accordingly, i~ has bxn found n~y to ~unhcr pT~CCSS
plastic and olher sof~ materials. An &~ditional proccssing unil may bc cmployod or thc mate~ial may simply bo stockpiled and r~ through at~i~ion scrtbber 70. This ~ddidonal prooessing involv~s contac~ng thc soft, plastic rnaterials with a basic aqueous ~olution to dissolve lhc cont~inati~ lead.
Fig. 3 lllustratcs in delail ~he mcthod for furthcr procasing the~ Icad contaminated plastic ma~erials~ L~ead-contar~nQte~l plastic in s~ckpilc 110 is delilrercd ~ria convcyor 112 to attrition scrubber 120 for v.i~orous, high energy scrubbing. ~ttsition scrubber 120 is equipped w~th a plu~ality of ~gitato~ 1~ drivcn by a plurality of motors 1~4. ScnJbbing 10 conditions, i.e., snLlong spee~, ternp~ature, prcssur~, residence time and ~he like arc lhe same as discussed abovc with respect to scru~bcr 70. ~ccause of thc lower density of plastic, i~
may not be possible to ~chieve thc solids rl~io pr~ferred with the ebonites and hard rubbers.
A~tntion scrubber 120 should be operatcd wi~h ~ solids ratio of about 30 ~o about 80 perccnt-b~ wdgh~ solids, ~nd prefe~ably abou~ 30 ~o about ~0 p~nt-by-wei~:hl solids to achieve 15 maximurn cfficiency of lead dissolution.
~ he UlUSliC leach solution is prepared in mi~in~ ~ank 130 and delivered via pump 126 lhough linc 128 ~o ~taition scrubbcr 120. The leach solution should be at a p~ greater than about 7 and prefes~bl~ grea~cr than about 10. The prcfcrrcd lchin~ solu~ion is an aqucous ,hydroxj~e solution, prefe~bly an alhli, alkaline ca~th or ammonium hydroxidc, and most ~0 prefe~rably sodium hydroxlde. Thecaustic compound, pneFe~ably sod;um hydroxide, i5 present ~etwecn about 0.5 and about ~ O or mor~ per~ent by-weight in wa~, more preferably betwecn about 1 and aboul S perccnt by-wcight, most prefably about 2 pcrccnt-by~weighl in a4u~ous solution. 'rhc mi~ture of plas~ic and solution from attrition sc-ubbcr 120 i5 dcl;vered via line 132 to wash ~creen 134. 'rhe pli~stic is removed to convenLional screw classlflcr 140 wherc .
~UL 2EI ' 93 15: 33 713 Z66 5169 PF~GE . 005 ` I . ,.

JUL-20--L993 L4:26 FROM i3ROlJ~llN;. 13USHt1~ D-RS TO L63::44323E!~ R ~6 - 15 ~ ,J L~
2ny resid~al insolublc materials with densides grca~er Ihan water arc rcmoved via line 138.
Ftom classifier 140, t~c clcaned, plastic rna~crial is dclivered via linc 142 lo second screen 150 where wash water from sourcc l44 is added. The cleaned, plastic ma~erial floa~ing on screen lSO ~ remov~ via line 146 ~o a clean product rec~ptaclc.
1~ ~ash vva~er from scseen IS0 is dr~unod through line 148 ~nd p-lmped v;a pump 152 Shrough line 148 for combination u~ith ~he wa~h watcr ftom screen l34 pumped ~da line 154 uQng pump 1~6. This filbate comprises the aqueous hydro~ide solution containing d~ssol~i lead. This solution ~s deliYcred to carbonatot 160 where car~on dio~idc from tank lS8 is ~ded via line 162 to convert the lead so Icad ca~bonate for precipilation and rcmoval.
10 The output of Glsbona10r 160 is ddivered via line 164 to tank 170 for thickcning by precipitation. The scttlod l~d carbonatc may be recovcred via.linc 16~ while the clarified soluti~D is d~wn from tank 170 via linc 168 f~r use in silc dust con~ol (Fig. 1).
Effectivencss of the pn~ccsses of the prcscnt inYcntion may ~e seen by ~hc following cxarnplc wherdn several diffcrcnt ~ng Tnatcrials vve t~ated by the proccsscs of thc lS prcsen~ invention. rhe re~uldng ebonl~e and plas~c materials w~ analy~od ~r leachablc lead in accord with thc ~ o~ p~cedure and ~c results ~eportod in Tables 11 and 111, respocdvcly.

JUL S~ 93 15 33 713 266 5169 P~GE . 006 'i '! ' . u_--~a--. 77J ~ cr~r r<ul I r,r~ , U ~r._;,~.,--, ., ~.. .__ _ _ . _ _ _ . . _ _ _ __ . _ W V ~ v ~ _ ~v -~6- ~6()l ~` . - ;, ;
I'P,BLE: I I
~I'rS0?~ 8C:RUg131NG 0~ EBOr~lTl!: W~TH 'i1A~R-S ~ ~ _ _ S~DP1~ A SU~P1Q B S~p1e C
S~d~ox L~ad Lelld PTox Le~ ~oad ~SP~ox 5~ad ~PP~) tPF~) ~PE~) ~P~) (PE~) (pEm) :' 1~- _ . ~ . :'.
t: 4503.5 ~80 1.~ 310 C.2 ,-~llot ~t~ 3003.6 _ _ _ _ .,, 15~ullc Skoe~ nq:~00 i3 6 320 3 . B490 ~ . 4 Oaoon~ts~lon: S~0 ~ . 4 _ _ _ _ . ' _ __ ., .~bon~t~ w~~uh2~cd ln ~ter ~t 60-70 par~ent-by-welgh'~ ~011~19 ~bonlt~ or 30 ~ln~t~.
- 25 - ' ' "
S~B~ ~ l5I
Am~$10N SC~98ING oP P~AST~C ~H cAt~s$I
. _ somp1~ D S~ pl~ ~:
3060ruh~lng Sltae Le~d ~P~o~ ~ad ~e~d ~o~ Leiad ~ln. ~ ~ pPs~) tPF~n~ (P~) __ _ 35 0 3290 23.3-36.7 26~0 ~9~5 490 lO.0 ~oO 2.1 950 3.2 480 0.6 :
40~0 500 0 . 9 710 - ~
_ . ' ~.
~P1-~tLo ~7~e oc~ bbcd ln 2 p-~rc-r~t-by-welght odlum hydrox~de ~t 35 pe~cerlt-45 by-wol~ht ~olld~ ~pl~-~lc~

The fotegoing dcscription of the inv~n~ion has bcen direcled in prima~y part ~o a panicul~r prcferred em~odiment in accordance with ~hc requirements of the ptent staNtes and ~r pu~poses of explanatios~ and illustration. 1~ will be apparcnt, howcver, to ~hose s~]lod in " l!

JUL 20 '93 15:33 713266 5169 P~GE.0E~7 .. -.

.... . .

.
~ - ' , , .
. .`:: . . .

JUL-Z2-1993 14:27 FROIl 8ROWNING, BUSHrl~N. P~ S TO 160 '14~C~ r,28 ..~, ,_ ._,,, - 17- ~lU~Ol thc a~ ~hat many modifications and chan~s in ~he specifically descr`ibed syst~m m~y be made ~ithout dcpaJting from the true scop~ and spiri~ of the imention. ThercSore, ~e invcn~ion iS DO~ resb-ictet to the prefersed embo~iments describ~d, but covers all modifications which may fàll within the ~cope of tbe following claims. -- :
.: ~

~ . .

713 Z66 5169 PRGE . 0a3 JUL 20 ' 93 1 5: 34 .. . . .

Claims

1. A method for controlling airborne spreading of lead and lead-contaminated fines and dust from materials including said fines and dust, comprising:
wetting the surface of said materials with an aqueous solution including an effective amount of a wetting agent.

2. The method of Claim 1 wherein said wetting agent is an inorganic wetting agent.

3. The method of Claim 2 wherein said wetting agent is selected from the group consisting of the carbonates, bicarbonates, sesquicarbonates and mixtures thereof.

4. The method of Claim 3 wherein the cation of said wetting agent is selected from the group consisting of the alkali metals, the alkaline earth metals, ammonium and mixtures thereof.

5. The method of Claim 1 wherein said wetting agent is selected from the group consisting of sodium carbonate, sodium sesquicarbonate and mixtures thereof.

6. The method of Claim 1 wherein said solution comprises from about 0.5 to about 3 percent-by-weight wetting agent.

7. The method of Claim 5 wherein said solution comprises about 2 percent-by-weight sodium sesquicarbonate.

8. The method of Claim 1 wherein said materials are wetted by spraying with said aqueous solution.

9. The method of Claim 1 wherein said materials are selected from the group consisting of plastics, ebonites, hard rubbers and mixtures thereof.

WO 92/14?9? 20 PCT/US?2/?????

10. A method for reducing the lead and leachable lead content of lead-contaminated materials, comprising:
contacting said lead-contaminated materials with an aqueous solution of a soluble inorganic salt which forms a stable, insoluble lead salt in said solution; and separating the cleaned materials from said lead salt.

11. The mehod of Claim 10 wherein insoluble lead salt is lead carbonate.

12. The method of Claim 10 wherein said soluble inorganic salt is selected from the group consisting or the soluble carbonates, bicarbonates, sesquicarbonates and mixtures thereof.

13. The method of Claim 10 further comprising vigorously mixing said materials with said aqueous. solution in a scrubber to enhance leaching and dissolution of said contaminants.

14. The method of Claim 13 further comprising separating said cleaned materials from said lead said by washing with an aqueous wash selected from the group consisting of water and said aqueous solution.

??????? ?? ????????

15. A method for reducing the lead and leachable lead content of fragments of ebonite, other hard rubbers and mixtures thereof to which are adhered lead contaminants such as lead sulfate, lead oxides, metallic lead and mixtures thereof, comprising:
abrading said lead contaminants from said fragments sized between about 10 mesh and 1.5 inches by scrubbing in a high energy attrition scrubber a mixture comprising from about 60 to about 80 percent-by-weight of said lead-contaminated fragments in water for a time of about 15 minutes to about 2 hours and at a temperature between about 40°F and about 120°F;
transferring the abraded mixture to a floatation tank; and separating clean fragments from water containing the abraded lead contaminants by removing the floating, clean fragments from the surface of the said mixture in said floatation tank.

WO 92/14?9? 22 PCT/US92/0?430

16. A method for reducing the lead and leachable lead content of hard surface materials to which are adhered lead contaminants, comprising:
abrading said lead contaminants from said hard surface materials by scrubbing in a high energy scrubber a mixture of said lead contaminated materials and water; and separating the cleaned hard surface materials from said water containing the abrading contaminants.

17. The method of Claim 16 wherein said hard surface materials are less dense than water.

18. The method of Claim 17 wherein said hard surface materials are selected from the group consisting of ebonites, hard rubbers and mixtures thereof.

19. The method of Claim 16 wherein said abrading is performed in an attrition scrubber and said mixture comprises from about 30 to about 80 percent-by-weight solids.

20. The method of Claim 19 wherein the residence time of said contaminated, hard surface materials in said attrition scrubber is from about 15 minutes to about 2 hours.

21. The method of Claim 16 comprising sizing said hard surface materials to between about 10 mesh and about 1.5 inches prior to said abrading.

??????? 23 ??????????

22. Scrap/recyclable hard surfaces materials comprising ebonites, hard rubbers or mixtures thereof produced by abrading lead contaminants from contaminated hard surface materials by scrubbing in a high energy scrubber a mixture of said lead contaminated materials and water, and separating the cleand hard surface materials from said water containing the abraded contaminants.

23. The scrap/recyclable hard surface materials of Claim 22 further characterized by an extractable procedure toxicity (EPTox) value of less than about 5 ppm lead.

????????? ?? ????????????

24. A method for reducing the lead and leachable lead content of plastic materials containing lead contaminants such as lead sulfate, lead oxides, metallic lead and mixtures thereof, comprising:
leaching said lead contaminants from said plastic materials sized between about 10 mesh and about 1.5 inches by mixing in a high energy scrubber with an aqueous solution comprising from about 1 to about 3 percent-by-weight sodium hydroxide for a time of about 15 minutes to about 2 hours and at a temperature between about 40°F and about 120°F, comprising mixture from about 30 to about 60 percent-by-weight solids;
transferring said mixture to a floatation tank; and separating the clean plastic materials from said aqueous solution containing dissolved lead contaminants by removing the floating, clean plastic materials from the surface of said solution in said floatation tank.

25. A method for reducing the lead and leachable lead content of plastic materials containing lead contaminants, comprising:
leaching said lead contaminants from said plastic materials with an aqueous solution having a pH greater than about 7; and separating the cleaned, plastic materials from said aqueous solution containing the leached contaminants.

26. The method of Claim 25 wherein the pH of said aqueous solution is greater than about 10.

27. The method of Claim 25 wherein said solution comprises an aqueous solution of an hydroxide.

28. The method of Claim 2? wherein said hydroxide is selected from the group consisting of the alkali hydroxides, the alkaline earth hydroxides, ammonium hydroxide and mixtures thereof.

29. The method of Claim 28 wherein said hydroxide is sodium hydroxide.

30. The method of Claim 27 wherein said aqueous solution comprises from about 0.5 to about 10 percent-by-weight of said hydroxide.

??????? ?? ??????????

31. The method of Claim 25 wherein said aqueous solution comprises from about 1 lo about 3 percent-by-weight sodium hydroxide.

32. The method of Claim 25 further comprising mixing said plastic materials and said aqueous solution in a high energy scrubber to enhance said leaching and dissolution of said lead contaminants.

33. The method of Claim 32 wherein said mixing is performed in an attrition scrubber and said mixture comprises from about 30 to about 80 percent-by-weight solids.

34. The method of Claim 25 wherein said plastic materials are leached for about 15 minutes to about 2 hours.

35. The method of Claim 25 further comprising converting the lead which is leached into said aqueous solution to lead carbonate and removing the lead carbonate by precipitation and separation from said aqueous solution.

36. The method of Claim 25 comprising sizing said plastic materials to between about 10 mesh and about 1.5 inches prior to said leaching.

37. Scrap/recyclable plastic materials produced by leaching lead contaminants from contaminated plastic materials with an aqueous solution having a pH greater than about 7, and separating the cleaned, plastic materials from said aqueous solution containing the leached contaminants.

38. The scrap/recyclable plastic materials of Claim 37 further characterized by an extractable procedure toxicity (EPTox) value of less than about 5 ppm lead.

v

39. A method for processing a mixture of lead-contaminated materials, including lead contaminated hard and soft polymeric materials, comprising:
processing the constituents of said mixture to be within a predetermined size;
separating from said mixture said lead-contaminated polymeric materials by mixing said mixture in a trommel scrubber and washing with a wash solution to remove lead fines;
separating said lead fines from said wash solution;
recycling the separated wash solution for use in wetting said lead-contaminate materials;
scrubbing said lead-contaminated polymeric materials in a high energy scrubber with water to abrade lead contaminants from the surface of hard surface polymeric materials;
separating the cleaned, hard surface polymeric materials from said water containing the abraded contaminants;
separating said abraded contaminants from said water;
recycling said separated water for use in said high energy scrubber;
contacting said lead-contaminated soft polymeric materials with an aqueous solution having a pH greater than about 7 to leach said lead contaminants therefrom;

separting the cleaned, soft polymeric materials from said aqueous soltuion containing the leached contaminants;
separing said leached contaminants from said aqueous solution; and recycling the separated aqueous solution for use in wetting said lead-contaminated materials.