U.S. patent application number 14/389142 was filed with the patent office on 2015-02-19 for removal of lead from solid materials.
This patent application is currently assigned to Entegris, Inc.. The applicant listed for this patent is Tianniu Chen, Ping Jiang, Michael B. Korzenski. Invention is credited to Tianniu Chen, Ping Jiang, Michael B. Korzenski.
Application Number | 20150050199 14/389142 |
Document ID | / |
Family ID | 49301072 |
Filed Date | 2015-02-19 |
United States Patent
Application |
20150050199 |
Kind Code |
A1 |
Korzenski; Michael B. ; et
al. |
February 19, 2015 |
REMOVAL OF LEAD FROM SOLID MATERIALS
Abstract
A leaching composition that substantially removes lead from
solid materials and a method of using said composition. Preferably,
the concentration of lead in the solid materials following
processing is low enough that the solid materials can be reused
and/or disposed of at minimal cost to the processor. Preferably,
the solid materials comprise glass, such as cathode ray tube
glass.
Inventors: |
Korzenski; Michael B.;
(Bethel, CT) ; Chen; Tianniu; (Westford, MA)
; Jiang; Ping; (Danbury, CT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Korzenski; Michael B.
Chen; Tianniu
Jiang; Ping |
Bethel
Westford
Danbury |
CT
MA
CT |
US
US
US |
|
|
Assignee: |
Entegris, Inc.
Danbury
CT
|
Family ID: |
49301072 |
Appl. No.: |
14/389142 |
Filed: |
April 5, 2013 |
PCT Filed: |
April 5, 2013 |
PCT NO: |
PCT/US2013/035379 |
371 Date: |
September 29, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61621073 |
Apr 6, 2012 |
|
|
|
Current U.S.
Class: |
423/98 |
Current CPC
Class: |
H01J 9/52 20130101; Y02W
30/60 20150501; Y02P 10/20 20151101; Y02W 30/82 20150501; Y02W
30/828 20150501; Y02P 10/212 20151101; C22B 13/045 20130101 |
Class at
Publication: |
423/98 |
International
Class: |
C22B 3/00 20060101
C22B003/00 |
Claims
1. A method of leaching lead or other heavy metals from solid
materials, said method comprising: pulverizing the solid materials
to size in a range from about 10 microns to about 3 mm; introducing
the pulverized solid materials into a chemical processing vessel
comprising a leaching composition to form a slurry; agitating the
slurry to leach the lead or other heavy metals from the solid
material into the leaching composition, wherein the leaching
composition comprises at least one oxidant, at least one solvent,
optionally at least one metal chelator, optionally at least one
accelerator/NO.sub.x (nitrogen oxide) suppressor, and optionally at
least one etchant.
2. The method of claim 1, wherein the solid material comprises
cathode ray tube glass, soil, paint chips, electronic waste, and
solder sludge.
3. The method of claim 1, wherein the agitation occurs in the
presence of added heat.
4. The method of claim 1, further comprising filtering the solid
material from the leaching composition.
5. The method of claim 4, further comprising rinsing the solid
material with a rinse composition to remove residual leaching
composition therefrom.
6. The method of claim 4, further comprising processing the
leaching composition to recapture the lead or other heavy
metals.
7. The method of claim 1, wherein the material comprises glass and
wherein the lead or other heavy metals on the surface of the
pulverized solid material have been substantially removed.
8. The method of claim 1, wherein the at least one oxidant
comprises ozone, nitric acid, bubbled air, cyclohexylaminosulfonic
acid, hydrogen peroxide, oxone, ammonium peroxomonosulfate,
ammonium chlorite, ammonium chlorate, ammonium iodate, ammonium
perborate, ammonium perchlorate, ammonium periodate, ammonium
persulfate, ammonium hypochlorite, sodium persulfate, sodium
hypochlorite, potassium iodate, potassium permanganate, potassium
persulfate, potassium persulfate, potassium hypochlorite,
tetramethylammonium chlorite, tetramethylammonium chlorate,
tetramethylammonium iodate, tetramethylammonium perborate,
tetramethylammonium perchlorate, tetramethylammonium periodate,
tetramethylammonium persulfate, tetrabutylammonium
peroxomonosulfate, peroxomonosulfuric acid, urea hydrogen peroxide,
peracetic acid, sodium nitrate, potassium nitrate, ammonium
nitrate, sulfuric acid, methanesulfonic acid (MSA), ethanesulfonic
acid, 2-hydroxyethanesulfonic acid, n-propanesulfonic acid,
isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic
acid, and n-octanesulfonic acid, and combinations thereof.
9. The method of claim 1, wherein the at least one oxidant
comprises methanesulfonic acid, nitric acid, or a combination of
methanesulfonic acid and nitric acid.
10. The method of claim 1, wherein the leaching composition
comprises the at least one metal chelator, wherein the at least one
metal chelator comprises a species selected from the group
consisting of acetylacetonate, 1,1,1-trifluoro-2,4-pentanedione,
1,1,1,5,5,5-hexafluoro-2,4-pentanedione, formates, acetates,
bis(trimethylsilylamide) tetramer, glycine, serine, proline,
leucine, alanine, asparagine, aspartic acid, glutamine, valine, and
lysine, citric acid, acetic acid, maleic acid, oxalic acid, malonic
acid, succinic acid, phosphonic acid, hydroxyethylidene
diphosphonic acid (HEDP), 1-hydroxyethane-1,1-diphosphonic acid,
nitrilo-tris(methylenephosphonic acid), nitrilotriacetic acid,
iminodiacetic acid, etidronic acid, ethylenediamine,
ethylenediaminetetraacetic acid (EDTA),
(1,2-cyclohexylenedinitrilo)tetraacetic acid (CDTA), uric acid,
tetraglyme, pentamethyldiethylenetriamine (PMDETA),
1,3,5-triazine-2,4,6-thithiol trisodium salt solution,
1,3,5-triazine-2,4,6-thithiol triammonium salt solution, sodium
diethyldithiocarbamate, disubstituted dithiocarbamates, ammonium
sulfate, monoethanolamine (MEA), Dequest 2000, Dequest 2010,
Dequest 2060s, diethylenetriamine pentaacetic acid,
propylenediamine tetraacetic acid, 2-hydroxypyridine 1-oxide,
ethylendiamine disuccinic acid (EDDS),
N-(2-hydroxyethyl)iminodiacetic acid (HEIDA), sodium triphosphate
penta basic, ammonium chloride, sodium chloride, lithium chloride,
potassium chloride, ammonium sulfate, hydrochloric acid, sulfuric
acid, and combinations thereof.
11. The method of claim 1, wherein the leaching composition
comprises the at least one metal chelator, wherein the at least one
metal chelator comprises ammonium chloride, sodium chloride,
lithium chloride, potassium chloride, ammonium sulfate,
hydrochloric acid, sulfuric acid, and combinations thereof.
12. The method of claim 1, wherein the leaching composition
comprises the at least one accelerator/NO.sub.x (nitrogen oxide)
suppressor, wherein the at least one accelerator/NO.sub.x
suppressor comprises a species selected from the group consisting
of ascorbic acid, adenosine, L(+)-ascorbic acid, isoascorbic acid,
ascorbic acid derivatives, citric acid, ethylenediamine, gallic
acid, oxalic acid, tannic acid, ethylenediaminetetraacetic acid
(EDTA), uric acid, 1,2,4-triazole (TAZ), benzotriazole (BTA),
tolyltriazole, 5-phenyl-benzotriazole, 5-nitro-benzotriazole,
3-amino-5-mercapto-1,2,4-triazole, 1-amino-1,2,4-triazole,
hydroxybenzotriazole, 2-(5-amino-pentyl)-benzotriazole, 1
-amino-1,2,3 -triazol e, 1 -amino-5-methyl-1,2,3-triazol e,
3-amino-1,2,4-triazole, 3-mercapto-1,2,4-triazole,
3-isopropyl-1,2,4-triazole, 5-phenylthiol-benzotriazole,
halo-benzotriazoles (halo=F, Cl, Br or I), naphthotriazole),
4-amino-1,2,4-triazole (ATAZ), 2-mercaptobenzimidazole (MBI),
2-mercaptobenzothiazole, 4-methyl-2-phenylimidazole,
2-mercaptothiazoline, 5-aminotetrazole (ATA),
5-amino-1,3,4-thiadiazole-2-thiol,
2,4-diamino-6-methyl-1,3,5-triazine, thiazole, triazine,
methyltetrazole, 1,3-dimethyl-2-imidazolidinone,
1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole,
diaminomethyltriazine, imidazoline thione, mercaptobenzimidazole,
4-methyl-4H-1,2,4-triazole-3-thiol,
5-amino-1,3,4-thiadiazole-2-thiol, benzothiazole, tritolyl
phosphate, imidazole, indiazole, benzoic acid, boric acid, malonic
acid, ammonium benzoate, catechol, pyrogallol, resorcinol,
hydroquinone, cyanuric acid, barbituric acid,
1,2-dimethylbarbituric acid, pyruvic acid, adenine, purine,
phosphonic acid and derivatives thereof, glycine/ascorbic acid,
Dequest 2000, Dequest 7000, p-tolylthiourea, succinic acid,
phosphonobutane tricarboxylic acid (PBTCA), sodium molybdate,
ammonium molybdate, salts of chromate (e.g., sodium, potassium,
calcium, barium), sodium tungstate, salts of dichromate (e.g.,
sodium, potassium, ammonium), suberic acid, azaleic acid, sebacic
acid, adipic acid, octamethylene dicarboxylic acid, pimelic acid,
dodecane dicarboxylic acid, dimethyl malonic acid, 3,3-diethyl
succinic acid, 2,2-dimethyl glutaric acid, 2-methyl adipic acid,
trimethyl adipic acid, 1,3-cyclopentane dicarboxylic acid,
1,4-cyclohexane dicarboxylic acid, terephthalic acid, isophthalic
acid, 2,6-naphthalene dicarboxylic acid, 2,7-naphthalene
dicaroxylic acid, 1,4-naphthalene dicarboxylic acid,
1,4-phenylenedioxy diacetic acid, 1,3-phenylenedioxy diacetic acid,
diphenic acid, 4,4'-biphenyl dicarboxylic acid, 4,4'-oxydibenzoic
acid, diphenylmethane-4,4'-dicarboxylic acid,
diphenylsulfone-4,4'-dicarboxylic acid, decamethylene dicarboxylic
acid, undecamethylene dicarboxylic acid, dodecamethylene
dicarboxylic acid, orthophthalic acid, naphthalenedicarboxylic
acid, paraphenylenedicarboxylic acid, trimellitic acid,
pyromellitic acid, sodium hexametaphosphate, sodium silicates,
1-arginine, adensosine, adenine, and combinations thereof.
13. The method of claim 1, wherein the leaching composition
comprises the at least one accelerator/NO.sub.x (nitrogen oxide)
suppressor, wherein the at least one accelerator/NO.sub.x
suppressor comprises ATAZ, TAZ, triazole derivatives, or
combinations thereof.
14. The method of claim 1, wherein the solvent comprises water.
15. The method of claim 1, wherein the leaching composition
comprises the at least one etchant, wherein the at least one
etchant is selected from the group consisting of at least one
carbonate species, at least one hydroxide species, at least one
fluoride species, and any combination thereof.
16. The method of claim 15, wherein the at least one etchant
comprises a species selected from the group consisting of sodium
carbonate; potassium carbonate; sodium hydrogen carbonate; LiOH;
NaOH; KOH; RbOH; CsOH; Mg(OH).sub.2; Ca(OH).sub.2; Sr(OH).sub.2;
Ba(OH).sub.2; NR.sub.4OH, wherein R can be the same as or different
from one another and include H, C.sub.1-C.sub.6 alkyl,
C.sub.6-C.sub.10 aryl, and combinations thereof; xenon difluoride;
HF; pentamethyldiethylenetriammonium trifluoride; ammonium
bifluoride; triethylaminogallate trihydrofluoride; alkyl hydrogen
fluoride (NRH.sub.3F), wherein each R is independently selected
from hydrogen and C.sub.1-C.sub.4 alkyl; dialkylammonium hydrogen
fluoride (NR.sub.2H.sub.2F), wherein each R is independently
selected from hydrogen and C.sub.1-C.sub.4 alkyl; trialkylammonium
hydrogen fluoride (NR.sub.3HF), wherein each R is independently
selected from hydrogen and C.sub.1-C.sub.4 alkyl; trialkylammonium
trihydrogen fluoride (NR.sub.3:3HF), wherein each R is
independently selected from hydrogen and C.sub.1-C.sub.4 alkyl;
ammonium fluorides of the formula R.sub.4NF, wherein each R is
independently selected from hydrogen, C.sub.1-C.sub.4 alkyl, and
C.sub.1-C.sub.4 alkanol; and combinations thereof.
Description
FIELD
[0001] The present invention relates generally to a composition
that substantially removes lead from solid materials, and a method
of using said composition.
DESCRIPTION OF THE RELATED ART
[0002] As the world transitions to flat panel televisions and flat
panel computer monitors, more and more cathode ray tubes (CRTs) are
being discarded. The safe disposal of CRTs present a serious
environmental challenge since they contain leaded glass (primarily
in the funnel, neck and frit) which may be readily leached from a
landfill by acidic water. The lead content in the glass of a CRT
can be as high as 20%, which means that a single 34'' television
might contain more than 1 kg of lead. Lead is toxic and is known to
damage the body's nervous and reproductive systems and kidneys. It
can also cause high blood pressure and anemia. Lead is especially
harmful to the developing brains of fetuses and young children and
to pregnant women. As a result, lead has been banned from fuel,
paint, pipes and all new electronics.
[0003] Recycling glass is manually intensive and expensive. This is
so because one vendor of glass may use different concentrations of
lead or other metals in their glass products than another glass
vendor. Waste disposal facilities receive glass waste that is not
separated, and the waste disposal facilities have no effective
techniques for automatically separating different glass wastes from
one another. Because of the expense and time consuming nature
associated with recycling glass waste, many waste disposal
facilities have resorted to the illegal disposal of glass
waste.
[0004] In the past, the most popular and legal technique for
disposing of CRTs is a smelting technique, wherein the glass of the
monitor is melted at an extremely high temperature and the lead
extracted off the top of the liquid produced. A literature survey
indicates that smelting recovers only 50% of the lead in the glass,
produces toxic vapors and a contaminated toxic slag that is either
landfilled (at high cost) or used as a low-value aggregate.
Therefore, the EPA realizes that it cannot permit the smelting
process to continue indefinitely and is actively pursuing and
promoting research to replace the process. Currently, CRT waste is
the number two contributor to hazardous lead waste in the United
States.
[0005] Since no truly viable solution to this problem exists,
millions of tons of waste glass are being stockpiled by electronics
recyclers looking for a solution. Reuse is not a real option since
relatively few new CRTs are being manufactured. This problem will
only get worse as liquid crystal and/or plasma screen technology is
integrated into the industry and the at least 1.9 billion CRTs
still in use worldwide are systematically disposed of.
[0006] Accordingly, there is a need for improved techniques to
extract heavy metals from glass waste products and other materials
comprising said heavy metals. The techniques should be
environmentally safe, efficient, and practical so that the
techniques are readily embraced and adopted by waste disposal
facilities.
SUMMARY
[0007] The present invention generally relates to a composition
that substantially removes lead from solid materials, and a method
of using said composition. Preferably, the concentration of lead in
the solid materials following processing is low enough that the
solid materials can be reused and/or disposed of at minimal cost to
the processor. Preferably, the solid materials comprise glass, such
as cathode ray tube glass.
[0008] In one aspect, a method of leaching lead or other heavy
metals from solid materials, said method comprising:
[0009] pulverizing the solid materials to size in a range from
about 10 microns to about 3 mm;
[0010] introducing the pulverized solid materials into a chemical
processing vessel comprising a leaching composition to form a
slurry;
[0011] agitating the slurry to leach the lead or other heavy metals
from the solid material into the leaching composition, wherein the
leaching composition comprises at least one oxidant, at least one
solvent, optionally at least one metal chelator, optionally at
least one accelerator/NO.sub.x (nitrogen oxide) suppressor, and
optionally at least one etchant.
[0012] In another aspect, a leaching composition is described, said
leaching composition comprising at least one oxidant, at least one
solvent, optionally at least one metal chelator, optionally at
least one accelerator/NO.sub.x (nitrogen oxide) suppressor, and
optionally at least one etchant.
[0013] Other aspects, features and advantages of the invention will
be more fully apparent from the ensuing disclosure and appended
claims.
DETAILED DESCRIPTION AND PREFERRED EMBODIMENTS THEREOF
[0014] The present invention generally relates to a composition
that substantially removes lead from solid materials, and a method
of using said composition to remediate lead from said solid
materials. Preferably, the concentration of lead in the solid
materials following processing is low enough that the solid
materials can be reused and/or disposed of at minimal cost to the
processor. Preferably, the solid materials comprise glass, such as
cathode ray tube glass. It is also contemplated that the
compositions described herein can be used to remove lead from soil,
electronic equipment, solder sludge, and paint chips.
[0015] As defined herein, "substantially devoid" corresponds to
less than about 2 wt. %, more preferably less than 1 wt. %, and
most preferably less than 0.1 wt. % of the composition, based on
the total weight of said composition.
[0016] "Substantially removed" is defined herein to mean that more
than 95 wt. % of the heavy metal originally present is dissolved or
otherwise solubilized, preferably more than 98 wt. %, more
preferably more than 99 wt. %, and most preferably more than 99.9
wt. %.
[0017] As used herein, the term "leaches" corresponds to the
complete removal or extraction of the lead or other metals from the
material into the leaching composition or the partial removal or
extraction of the lead or other metals from the material into the
leaching composition. The lead or other metals is dissolved or
otherwise solubilized in the leaching composition, preferably
dissolved.
[0018] As defined herein, the "material" corresponds to any solid
that requires lead or other metal remediation including, but not
limited to, CRT glass waste, soil, paint chips, electronic waste,
and solder sludge.
[0019] As has been discussed in detail above, glass waste,
particularly glass waste associated with CRT monitors or
televisions, includes unacceptable levels of lead, or other heavy
metals (e.g., cadmium, mercury, selenium, arsenic, and the like),
that need to be removed or decreased to acceptable levels before
the glass waste can be disposed of in a landfill. Using the
composition and method described herein, glass waste can
economically and safely be disposed of well within the current EPA
standards by safely and efficiently removing lead and other heavy
metals from the glass waste. Alternatively, the glass can safely be
recycled for reuse as glass or for incorporation into other
products such as concrete or asphalt.
[0020] The material, such as CRT glass waste, soil, paint chips,
electronic waste, and solder sludge, can be pulverized using means
suitable for crushing or grinding said materials to variable
particle sizes. For example, CRT glass waste can be fed to a
grinding device such as a high-speed hammer mill, grinder, or any
other size reduction means. Preferably, the material is pulverized
to size in a range from about 10 microns to about 3 mm. As the
material leaves the grinding means, preferably a separation device
classifies the material particles by size. For example, the
separation device can be configured to classify the material
particles into sizes between less than 3 mm and sizes greater than
approximately 10 microns. Material particles have a desired
diameter size between about 10 microns and about 3 mm or less,
although it should be appreciated that diameters less than 10
microns and greater than 3 mm can be processed as well using the
composition and method described herein.
[0021] The pulverized material particles are then introduced into a
chemical processing vessel comprising a leaching composition, which
will be described below. The chemical processing vessel can be a
drum set-up, a tumbler system, a mixing apparatus, or an equivalent
thereof. The leaching composition in combination with the
pulverized material particles results in the formation of a slurry,
which can be agitated by stirring, mixing, tumbling, shaking, etc.,
in the presence or absence of added heat. Preferably, the
temperature of the slurry during agitation is about 30.degree. C.
to about 150.degree. C., preferably about 30.degree. C. to about
70.degree. C. The slurry can alternatively be circulated using a
pumping system. In still another alternative, a feed-and-bleed
system is contemplated whereby some amount of the leaching
composition is removed for processing and fresh or recycled
leaching composition added to the chemical processing vessel.
[0022] The slurry can be agitated for time in a range from about 5
min to 6 hr, depending on the volume of leaching composition and
the amount of pulverized material particles added. Upon completion
of the leaching process, the leaching composition is removed from
the vessel and/or the material particles are filtered from the
leaching composition. Following filtration, the material particles
are preferably rinsed with water to remove residual leaching
composition from the material particles. Thereafter, the material
particles can be filtered again. The leaching composition can be
reused for another cycle of material particle treatment or treated
for disposal.
[0023] With regards to additional cycles, the leaching composition
can be reused until the leaching composition is saturated with lead
and other metals and no longer efficiently solubilizes lead into
the leaching composition. Ion-exchange resins selective to lead can
be used in combination with the leaching composition to further
extend the life of the bath. Moreover, as will be discussed below,
the leaching composition can be recycled using diffusion dialysis
and reused. With regards to disposal procedures, when no longer
viable, the leaching composition can be rendered essentially
non-toxic by electrowinning or precipitating the Pb and
neutralizing the excess acidity.
[0024] At this point, particles consisting of glass (e.g., CRT
glass) are substantially devoid of lead and other heavy metals on
their surface due to the mixing cycles with the leaching
composition. Moreover, any lead or heavy metal remaining within the
filtered glass particles cannot be extracted from the filtered
glass particles because of the size of the glass particle and the
fact that the remaining heavy metals are sequestered in the core.
Products, such as road materials and others, can include the
filtered glass particles with assurance that lead or other heavy
metals (e.g., cadmium, mercury, arsenic, selenium, and others) will
not be released. Therefore, the particles consisting of glass can
be used for other products such as foundations for roads, mixtures
for concrete, etc.
[0025] Preferably, all of the lead is removed from the material.
For example, when the material comprises soil or some other
amorphous solid, the leaching composition can penetrate the entire
material and the lead can be substantially removed from the
material. When the material comprises glass, only the lead on the
surface of the glass is removed. This is advantageous because the
lead in the core of the particle is sequestered and not easily
removed if disposed of in a landfill. That said, it is theorized
that if the leaching composition can solubilize the glass particle
then substantial removal of the lead can be effectuated and
substantially lead-free glass re-precipitated and sold for reuse.
As defined herein, "substantially lead-free" corresponds to a
concentration of lead in the material less than about 5 wt %,
preferably less than about 2 wt %, and even more preferably less
than 1 wt %, based on the total weight of the solid glass.
[0026] The leaching composition is formulated to oxidize and
sequester the lead thereby removing same from the material. The
leaching composition comprises, consists of, or consists
essentially of at least one oxidant, at least one solvent,
optionally at least one metal chelator, optionally at least one
accelerator/NO.sub.x (nitrogen oxide) suppressor, optionally at
least one etchant. In one embodiment, the leaching composition
comprises, consists of, or consists essentially of at least two
oxidants, at least one solvent, and at least one
accelerator/NO.sub.x (nitrogen oxide) suppressor. In another
embodiment, the leaching composition comprises, consists of, or
consists essentially of at least one oxidant, at least one solvent,
at least one metal chelator, and at least one accelerator/NO.sub.x
(nitrogen oxide) suppressor.
[0027] The components of the leaching composition comprising,
consisting of, or consisting essentially of at least two oxidants,
at least one solvent, and at least one accelerator/NO.sub.x
(nitrogen oxide) suppressor can be present in the following
amounts, based on the total weight of the leaching composition:
TABLE-US-00001 Component weight % oxidizing agent(s) about 6 wt %
to about 85 wt % accelerator/NO.sub.x suppressor(s) about 0.1 wt %
to about 10 wt % solvent(s) about 5 wt % to about 93.9 wt %
[0028] The components of the leaching composition comprising,
consisting of, or consisting essentially of at least one oxidant,
at least one solvent, at least one metal chelator, and at least one
accelerator/NO.sub.x (nitrogen oxide) suppressor can be present in
the following amounts, based on the total weight of the leaching
composition:
TABLE-US-00002 Component weight % oxidizing agent(s) about 5 wt %
to about 20 wt % metal chelator(s) about 10 wt % to about 65 wt %
accelerator/NO.sub.x suppressor(s) about 0.2 wt % to about 10 wt %
solvent(s) about 5 wt % to about 84.8 wt %
[0029] Oxidizing agents are included in the leaching composition to
oxidize the metals to be removed into an ionic form and accumulate
highly soluble salts of dissolved metals. Oxidizing agents
contemplated herein include, but are not limited to, ozone, nitric
acid (HNO.sub.3), bubbled air, cyclohexylaminosulfonic acid,
hydrogen peroxide (H.sub.2O.sub.2), oxone (potassium
peroxymonosulfate, 2KHSO.sub.5.KHSO.sub.4.K.sub.2SO.sub.4),
ammonium polyatomic salts (e.g., ammonium peroxomonosulfate,
ammonium chlorite (NH.sub.4ClO.sub.2), ammonium chlorate
(NH.sub.4ClO.sub.3), ammonium iodate (NH.sub.4IO.sub.3), ammonium
perborate (NH.sub.4BO.sub.3), ammonium perchlorate
(NH.sub.4ClO.sub.4), ammonium periodate (NH.sub.4IO.sub.3),
ammonium persulfate ((NH.sub.4).sub.2S.sub.2O.sub.8), ammonium
hypochlorite (NH.sub.4ClO)), sodium polyatomic salts (e.g., sodium
persulfate (Na.sub.2S.sub.2O.sub.8), sodium hypochlorite (NaClO)),
potassium polyatomic salts (e.g., potassium iodate (KIO.sub.3),
potassium permanganate (KMnO.sub.4), potassium persulfate,
potassium persulfate (K.sub.2S.sub.2O.sub.8), potassium
hypochlorite (KClO)), tetramethylammonium polyatomic salts (e.g.,
tetramethylammonium chlorite ((N(CH.sub.3).sub.4)ClO.sub.2),
tetramethylammonium chlorate ((N(CH.sub.3).sub.4)ClO.sub.3),
tetramethylammonium iodate ((N(CH.sub.3).sub.4)IO.sub.3),
tetramethylammonium perborate ((N(CH.sub.3).sub.4)BO.sub.3),
tetramethylammonium perchlorate ((N(CH.sub.3).sub.4)ClO.sub.4),
tetramethylammonium periodate 4N(CH.sub.3).sub.4)IO.sub.4),
tetramethylammonium persulfate
((N(CH.sub.3).sub.4)S.sub.2O.sub.8)), tetrabutylammonium polyatomic
salts (e.g., tetrabutylammonium peroxomonosulfate),
peroxomonosulfuric acid, urea hydrogen peroxide
((CO(NH.sub.2).sub.2)H.sub.2O.sub.2), peracetic acid
(CH.sub.3(CO)OOH), sodium nitrate, potassium nitrate, ammonium
nitrate, sulfuric acid, and combinations thereof. Although not
oxidizing agents per se, for the sake of the present disclosure,
oxidizing agents further include alkanesulfonic acids (e.g.,
methanesulfonic acid (MSA), ethanesulfonic acid,
2-hydroxyethanesulfonic acid, n-propanesulfonic acid,
isopropanesulfonic acid, isobutenesulfonic acid, n-butanesulfonic
acid, and n-octanesulfonic acid). The oxidizing agents can include
a combination of the any of the species defined herein as oxidizing
agent. The oxidizing agent may be introduced to the first
composition at the manufacturer, prior to introduction of the
leaching composition to the particles, or alternatively in situ.
Preferably, the oxidizing agent comprises methanesulfonic acid,
nitric acid, or a combination of methanesulfonic acid and nitric
acid.
[0030] When present, it is thought that an effective amount of
nitric acid serves as an accelerator of the leaching process.
Accordingly, in some embodiments, the oxidizing agent in the
leaching composition preferably comprises an alkane sulfonic acid
(e.g., MSA) and nitric acid, wherein the alkane sulfonic acid is
present in an amount ranging from 0.1 to 85 wt %, more preferably
from 5 to 45 wt %, and the nitric acid is present in an amount of
about 0.1 to 80 wt %, preferably from about 1 to 40 wt %.
[0031] Metal chelators are included to complex the metal ions
generated by the oxidizing agent. Metal chelators contemplated
herein include, but are not limited to: .beta.-diketonate compounds
such as acetylacetonate, 1,1,1-trifluoro-2,4-pentanedione, and
1,1,1,5,5,5-hexafluoro -2,4-pentanedione; carboxylates such as
formate and acetate and other long chain carboxylates; and amides
(and amines), such as bis(trimethylsilylamide) tetramer. Additional
chelating agents include amines and amino acids (i.e. glycine,
serine, proline, leucine, alanine, asparagine, aspartic acid,
glutamine, valine, and lysine), citric acid, acetic acid, maleic
acid, oxalic acid, malonic acid, succinic acid, phosphonic acid,
phosphonic acid derivatives such as hydroxyethylidene diphosphonic
acid (HEDP), 1-hydroxyethane-1,1-diphosphonic acid,
nitrilo-tris(methylenephosphonic acid), nitrilotriacetic acid,
iminodiacetic acid, etidronic acid, ethylenediamine,
ethylenediaminetetraacetic acid (EDTA), and
(1,2-cyclohexylenedinitrilo)tetraacetic acid (CDTA), uric acid,
tetraglyme, pentamethyldiethylenetriamine (PMDETA),
1,3,5-triazine-2,4,6-thithiol trisodium salt solution,
1,3,5-triazine-2,4,6-thithiol triammonium salt solution, sodium
diethyldithiocarbamate, disubstituted dithiocarbamates
(R.sup.1(CH.sub.2CH.sub.2O).sub.2NR.sup.2CS.sub.2Na) with one alkyl
group (R.sup.2=hexyl, octyl, deceyl or dodecyl) and one oligoether
(R.sup.1(CH.sub.2CH.sub.2O).sub.2, where R.sup.1=ethyl or butyl),
ammonium sulfate, monoethanolamine (MEA), Dequest 2000, Dequest
2010, Dequest 2060s, diethylenetriamine pentaacetic acid,
propylenediamine tetraacetic acid, 2-hydroxypyridine 1-oxide,
ethylendiamine disuccinic acid (EDDS),
N-(2-hydroxyethyl)iminodiacetic acid (HEIDA), sodium triphosphate
penta basic, sodium and ammonium salts thereof, ammonium chloride,
sodium chloride, lithium chloride, potassium chloride, ammonium
sulfate, hydrochloric acid, sulfuric acid, and combinations thereof
Preferably, the metal chelator comprises ammonium chloride, sodium
chloride, lithium chloride, potassium chloride, ammonium sulfate,
hydrochloric acid, sulfuric acid, and combinations thereof, most
preferably sodium chloride, sulfuric acid, or a combination of
sodium chloride and sulfuric acid.
[0032] When nitric acid is included in the leaching composition,
nitrogen oxides (NO.sub.x) are generated. Accordingly, NO.sub.x
suppressors are preferably included when the leaching composition
includes nitric acid. Surprisingly, however, the NO.sub.x
suppressors are also accelerators of the metal etch rates so they
can be added even if the leaching composition does not include
nitric acid. NO.sub.x suppressors/accelerators contemplated
include, but are not limited to, ascorbic acid, adenosine,
L(+)-ascorbic acid, isoascorbic acid, ascorbic acid derivatives,
citric acid, ethylenediamine, gallic acid, oxalic acid, tannic
acid, ethylenediaminetetraacetic acid (EDTA), uric acid,
1,2,4-triazole (TAZ), triazole derivatives (e.g., benzotriazole
(BTA), tolyltriazole, 5-phenyl-benzotriazole,
5-nitro-benzotriazole, 3-amino -5-mercapto -1,2,4-triazole,
1-amino-1,2,4-triazole, hydroxybenzotriazole,
2-(5-amino-pentyl)-benzotriazole, 1-amino -1,2,3-triazole,
1-amino-5-methyl-1,2,3 -triazole, 3-amino -1,2,4-triazole,
3-mercapto-1,2,4-triazole, 3-isopropyl-1,2,4-triazole,
5-phenylthiol-benzotriazole, halo-benzotriazoles (halo=F, Cl, Br or
I), naphthotriazole), 4-amino-1,2,4-triazole (ATAZ), 2-mercaptob
enzimidazole (MBI), 2-mercaptobenzothiazole,
4-methyl-2-phenylimidazole, 2-mercaptothiazoline, 5-aminotetrazole
(ATA), 5-amino-1,3,4-thiadiazole-2-thiol,
2,4-diamino-6-methyl-1,3,5-triazine, thiazole, triazine,
methyltetrazole, 1,3-dimethyl-2-imidazolidinone,
1,5-pentamethylenetetrazole, 1-phenyl-5-mercaptotetrazole,
diaminomethyltriazine, imidazoline thione, mercaptobenzimidazole,
4-methyl-4H -1,2,4-triazole-3-thiol, 5-amino-1,3
,4-thiadiazole-2-thiol, benzothiazole, tritolyl phosphate,
imidazole, indiazole, benzoic acid, boric acid, malonic acid,
ammonium benzoate, catechol, pyrogallol, resorcinol, hydroquinone,
cyanuric acid, barbituric acid and derivatives such as
1,2-dimethylbarbituric acid, alpha-keto acids such as pyruvic acid,
adenine, purine, phosphonic acid and derivatives thereof,
glycine/ascorbic acid, Dequest 2000, Dequest 7000, p-tolylthiourea,
succinic acid, phosphonobutane tricarboxylic acid (PBTCA), sodium
molybdate, ammonium molybdate, salts of chromate (e.g., sodium,
potassium, calcium, barium), sodium tungstate, salts of dichromate
(e.g., sodium, potassium, ammonium), suberic acid, azaleic acid,
sebacic acid, adipic acid, octamethylene dicarboxylic acid, pimelic
acid, dodecane dicarboxylic acid, dimethyl malonic acid,
3,3-diethyl succinic acid, 2,2-dimethyl glutaric acid, 2-methyl
adipic acid, trimethyl adipic acid, 1,3-cyclopentane dicarboxylic
acid, 1,4-cyclohexane dicarboxylic acid, terephthalic acid,
isophthalic acid, 2,6-naphthalene dicarboxylic acid,
2,7-naphthalene dicaroxylic acid, 1,4-naphthalene dicarboxylic
acid, 1,4-phenylenedioxy diacetic acid, 1,3-phenylenedioxy diacetic
acid, diphenic acid, 4,4'-biphenyl dicarboxylic acid,
4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid,
diphenylsulfone-4,4'-dicarboxylic acid, decamethylene dicarboxylic
acid, undecamethylene dicarboxylic acid, dodecamethylene
dicarboxylic acid, orthophthalic acid, naphthalenedicarboxylic
acid, paraphenylenedicarboxylic acid, trimellitic acid,
pyromellitic acid, sodium phosphates (e.g., sodium
hexametaphosphate), sodium silicates, amino acids and their
derivatives such as 1-arginine, nucleoside and nucleobases such as
adensosine and adenine, respectively, and combinations thereof.
Most preferably, the NO.sub.x suppressor/accelerator comprises
ATAZ, TAZ, triazole derivatives, or combinations thereof, most
preferably ATAZ.
[0033] Solvents contemplated herein include water, preferably
deionized water, as well as organic solvent such as alcohols,
glycol ethers, glycols, and carbonates, including, but not limited
to, methanol, ethanol, isopropanol, butanol, and higher alcohols
(including diols, triols, etc.), ethylene glycol, propylene glycol,
butylene carbonate, ethylene carbonate, propylene carbonate,
dipropylene glycol, diethylene glycol monomethyl ether, triethylene
glycol monomethyl ether, diethylene glycol monoethyl ether,
triethylene glycol monoethyl ether, ethylene glycol monopropyl
ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl
ether (i.e., butyl carbitol), triethylene glycol monobutyl ether,
ethylene glycol monohexyl ether, diethylene glycol monohexyl ether,
ethylene glycol phenyl ether, propylene glycol methyl ether,
dipropylene glycol methyl ether (DPGME), tripropylene glycol methyl
ether, dipropylene glycol dimethyl ether, dipropylene glycol ethyl
ether, propylene glycol n-propyl ether, dipropylene glycol n-propyl
ether (DPGPE), tripropylene glycol n-propyl ether, propylene glycol
n-butyl ether, dipropylene glycol n-butyl ether, tripropylene
glycol n-butyl ether, propylene glycol phenyl ether, and
combinations thereof, and combinations thereof Preferably, the
solvent comprises water.
[0034] When present, the at least one etchant can include at least
one carbonate species, at least one hydroxide species and/or at
least one fluoride species. Carbonates include, but are not limited
to, sodium carbonate, potassium carbonate, sodium hydrogen
carbonate, and combinations thereof Hydroxides contemplated
include, but are not limited to, alkali hydroxides, alkaline earth
metal hydroxides, metal ion-free hydroxides, and combinations
thereof such as LiOH, NaOH, KOH, RbOH, CsOH, Mg(OH).sub.2,
Ca(OH).sub.2, Sr(OH).sub.2, Ba(OH).sub.2, NR.sub.4OH, wherein R can
be the same as or different from one another and include H,
C.sub.1-C.sub.6 alkyl (e.g., methyl, ethyl, propyl, butyl, pentyl,
hexyl) or C.sub.6-C.sub.10 aryl (e.g., benzyl), and combinations
thereof. The at least one fluoride species may comprise a species
selected from the group consisting of xenon difluoride; HF;
pentamethyldiethylenetriammonium trifluoride; ammonium bifluoride;
triethylaminogallate trihydrofluoride; alkyl hydrogen fluoride
(NRH.sub.3F), wherein each R is independently selected from
hydrogen and C.sub.1-C.sub.4 alkyl (e.g., methyl, ethyl, propyl,
butyl); dialkylammonium hydrogen fluoride (NR.sub.2H.sub.2F),
wherein each R is independently selected from hydrogen and
C.sub.1-C.sub.4 alkyl; trialkylammonium hydrogen fluoride
(NR.sub.3HF), wherein each R is independently selected from
hydrogen and C.sub.1-C.sub.4 alkyl; trialkylammonium trihydrogen
fluoride (NR.sub.3:3HF), wherein each R is independently selected
from hydrogen and C.sub.1-C.sub.4 alkyl; ammonium fluorides of the
formula R.sub.4NF, wherein each R is independently selected from
hydrogen, C.sub.1-C.sub.4 alkyl, and C.sub.1-C.sub.4 alkanol (e.g.,
methanol, ethanol, propanol, butanol) such as ammonium fluoride,
tetramethylammonium fluoride, triethanolammonium fluoride,
tetraethylammonium fluoride; and combinations thereof. Preferably,
the fluoride source comprises HF, ammonium fluoride, or
combinations thereof When present the amount of etchant is
preferably in a range from about 0.01 wt % to about 10 wt %, based
on the total weight of the composition.
[0035] It is also contemplated herein that the combination of low
energy sonication or megasonics with leaching formulations also can
accelerate lead removal from CRT glass.
[0036] Advantageously, an easily recyclable leaching composition
can be employed in a closed-loop process generating minimal waste.
For example, when the leaching composition includes MSA, the MSA is
easily recycled using diffusion dialysis.
[0037] Most preferably, the leaching composition comprises,
consists or consists essentially of MSA, nitric acid, and ATAZ. In
another preferred embodiment, the leaching composition comprises,
consists of, or consists essentially of MSA, sulfuric acid, ATAZ,
and NaCl.
[0038] In another aspect, the leaching composition and the
pulverized CRT glass can be placed into a high pressure autoclave
for the leaching process. Water is known to have very strong
oxidizing properties at hydrothermal (>100.degree. C. and
>100 psi) conditions and near critical conditions
(>300.degree. C. and >3000 psi). Accordingly, at these
hydrothermal conditions, water alone may be strong enough to
oxidize the lead so that the chelator can extract the lead.
Suitable chelators include chloride, iodide, hydroxide, or sulfate
salts (e.g., as described herein), wherein hydroxide or sulfate are
preferred because they will not corrode steel vessels required for
high pressure applications and they will readily precipitate from
solution upon cooling and depressurizing of the vessel.
[0039] The resulting lead-free glass may be remelted for reuse
(e.g., bricks, tiles, foam), mixed into, for example, asphalt or
cement as a filler, or sent to a landfill for safe disposal. Lead
can be removed from the solution in the form of an oxide or salt
and may be resold. The system is closed so that no vapors escapes
and all of the chemistry and the rinse water are recycled for reuse
in the process. Small amounts of rinse water are discharged, but it
is first neutralized and has less than part-per-million trace
metals and no organics.
[0040] Although the invention has been variously disclosed herein
with reference to illustrative embodiments and features, it will be
appreciated that the embodiments and features described hereinabove
are not intended to limit the invention, and that other variations,
modifications and other embodiments will suggest themselves to
those of ordinary skill in the art, based on the disclosure herein.
The invention therefore is to be broadly construed, as encompassing
all such variations, modifications and alternative embodiments
within the spirit and scope of the claims hereafter set forth.
* * * * *