Solidification/stabilization of hazardous materials for recycling the industrial wastes
2006. 4 Ji-Whan Ahn
Korea Institute of Geoscience and Mineral Resource
Categories of wastes in Korea
Wastes
household waste
General industrial waste
Construction waste
Hazardous industrial waste Industrial waste
Sewage sludge
By generated field & industry
Wastes
Waste with high heavy metal content
Waste with low heavy metal content
By content of heavy metals
Recover potential energy value from the wastes Enhance process efficiency
→ Need to new recycling field for the consumption of the wastes
Trend of waste treatment
Many countries recognize that although the recycling is the best solution in their disposal,
it may not be viable, economically or due to the fact that recycling also generates further wastes.
Incineration
Recycling Landfill
- Insanitary - Lack of landfill
- Pollution in underground
- High investment &
operation cost - Air pollution, dioxin - Residue
- Refuse Derived Fuel (RDF)
- Alternative materials - Fertilizer
- More friendly to the environment
- Helpful in recovering energy from
waste
Co-incineration technique in cement industry
The co-incineration technique consists of partial substitution of raw materials or fuel for waste in a high temperature industrial process in such a manner that the waste is destroyed, the generated ash is incorporated in the product, and the product quality is not affected.
The co-incineration process provides an economy to the process in addition to providing a hazardous waste treatment methods
Cement Industry
Cement Industry
Cement industry & incinerator
• high volume and weight reduction
•generation of residues
• secondary pollution
Remarks
20-30wt.% of raw waste Residue
2sec Residence time
above 850oC Temperature
Incineration Item
Incinerator
Comparison cement kiln with incineratorabove 1,450oC
Ædecomposition of hazardous substances
Temperature
None Æ zero pollution Residue
5sec Residence time
• need for homogenizing of components
- control of heavy metals - control of volatile components
• use of present facilities
• mass treatment
Cement kiln
Remarks Item
Cement Industry
Recycling amount of wastes in cement industry
Cement Industry
[Million ton]
5.9 8.4
•Sludge & dust, slag etc
‘99
‘03
[Million ton]
0.1 0.4
• Sewage sludge
‘99 ‘03
Industry
Incinerator
- Iron making industry - Chemical industry - Power plant
[Million ton]
1.5 2.6
•Coal ash
‘99 ‘03 [Million ton]
•MSWI ash
‘99 ‘03 0.0 0.0
Increase rate for waste application in cement industry : about 10%, annually
To increase ratio of recycling amount, the studies on how to reuse as raw material in cement industry Especially, municipal solid wastes have to be used in cement industry
Emerging Technologies for Environmental friendly Materials
• Sewage sludge & Construction waste
• Sludge & dust, slag etc
• Fly & bottom ash
Manufacture Tec. Products Protect Env.
Treatment Tec.
Ordinary Portland Cement Special cement (CSA cement) (Calcium sulfo-aluminate)
Eco-cement (CCA cement) (Calcium chroline-aluminate)
Discharge of hazardous substances
- Dioxin - CO gas - SOx& NOxgas Envir. Stability of Products Volatilization/condensing
of volatile substances Heat distribution change in kiln
incomplete sintering/yellow clinker
Control wastes Tech.
- Mixing & Crushing - Separation - Content of water Storage of wastes
Emerging Tech.
Manufacture Tec. Products Protect Env.
Treatment Tec.
Emerging Tech.
Slag & Dust from POSCO MSWI bottom ash
Behavior of chlorine &
volatile substance in Kiln Produce OPC in Plant
Calcium sulfo-aluminate cement synthesis from slag from iron making industry Calcium chroline-aluminate
cement synthesis from MSWI ash
Ordinary Portland cement Manufacturing from inorganic wastes
Behavior of circulation of toxic gas
Estimation of discharge gas for air environment
Content of our research
Ordinary Portland Cement Special cement (CSA cement) (Calcium sulfo-aluminate)
Eco-cement (CCA cement) (Calcium chroline-aluminate)
Discharge of hazardous substances
- Dioxin - CO gas - SOx& NOxgas Envir. Stability of Products Volatilization/condensing
of volatile substances Heat distribution change in kiln
incomplete sintering/yellow clinker
Control wastes Tech.
- Mixing & Crushing - Separation - Content of water Storage of wastes
Applying waste as the raw material to cement industry, it is possible to influence to the cement products and process
→ To use wastes in cement industry, it is necessary to research on the behavior of heavy metals and alkali chlorine, and influence on the cement properties.
Emerging Technologies for Environmental friendly Materials in Korea
A Pretreatment for Cl Removal and Stabilization of Heavy Metal to
Recycle Municipal Solid Waste Incineration Bottom Ash
Disposal situation of municipal solid waste in Korea
z Generation of municipal solid waste in 2003 : about 15 million tons
z Incineration ratio : 5.5(1996) Æ 14.5(2003)
Category of municipal solid waste incineration ash
Fly ash Bottom ash
Korea
Mixed material collected from APC system including fly ash, injected adsorbent, flue gas condensate
Particulate material transported to the top of the incinerator and removed from flue gas.
Particulate material collected from the heat recovery system Material remaining after excluding grate siftings from bottom ash Material dropped through grate
Material discharged from the bottom of incinerator Location
APC Residue Fly Ash
Heat Recovery Ash(HRA) Grate Ash
Grate Siftings or Riddlings Bottom
Ash Category
Grate sifting or Riddlings Ash Fly Ash Boiler
APC residue Heat Recovery Ash(HRA)
Grate Ash
Bottom Ash
Fine particulate removal system Enclosed receiving area
Heat recovery system
1,000 5,000∼20,000
250
Commercial and industrial area HHS/ATSDR(’97)
EPA(’98)
residential district industrial area and road
40 10,000
1,000 1,000
commercial and industrial area
park residential district
playground
farm land 5∼40
1,000 10 1,000
100 (Pg-TEQ/g)
residential district USA
Residential district, farm land, playground
Sweden(’96)
town town
Objects
Netherlands(’97) Germany Countries
0.01 0.14
OCDD
0.04 0.53
1,2,3,4,6,7,8-HpCDD
0.21 0.58
1,2,3,7,8,9-HxCDD
0.29 0.76
1,2,3,6,7,8-HxCDD
0.18 0.26
1,2,3,4,7,8-TCDD
0.00 0.96
1,2,3,7,8-TCDD
0.00 0.77
2,3,7,8-TCDD
1.70 7.44
PCDFs
0.01 0.03
OCDF
0.03 0.05
1,2,3,4,7,8,9-HpCDF
0.03 0.53
1,2,3,4,6,7,8-HpCDF
0.24 0.18
1,2,3,7,8,9-HxCDF
0.22 1.14
2,3,4,6,7,8-HxCDF
0.14 0.87
1,2,3,6,7,8-HxCDF
0.09 0.41
1,2,3,4,7,8-HxCDF
0.92 3.65
2,3,4,7,8-PCDF
0.02 0.14
1,2,3,7,8-PCDF
0.00 0.44
2,3,7,8-TCDF
pg-TEQ/g pg-TEQ/g
Bottom ash D Bottom ash I
2,3,7,8-sustitution
Guidelines for soil pollution of dioxin in various countries
Amount of dioxins in bottom ash of Korea
- - - - - 1,000-500
- - - - 400*10-3-310*10-3
- - - - Mid-Corn
Dry Scrubber1 Dry Scrubber2 Dry Scrubber2 Dry Scrubber3 USA
1.8*10-3 2.0*10-3 0.8*10-3 96*10-3
91*10-3 94*10-3 36*10-3-39*10-3
41*10-3-48*10-3 25*10-3-29*10-3 A
B C Germany
- - - - - ND
ND ND
<0.2*10-3 ND ND
ND ND 400*10-3
ND GVRD
PEI LVH SWARU
QUC Canada
1/TEQ Total Furans
(PCDF) Total Dioxins
(PCDD) Facility
Country
Amount of dioxins and furans in bottom ash in various countries
Environmental hazardousness - dioxin
z Amount of dioxin in bottom ash satisfies environmental guidelines for soil pollution of dioxin
z Amount of dioxin in bottom ash satisfies environmental guidelines for soil pollution of dioxin
(unit:pg/g)
Removal & Solidification of chloride in MSWI bottom ash
- Synthesis of calcium chlorine-aluminate cement (CCA cement) -
• heavy metals and its compound
• • battery battery
• • vinyl vinyl
• • ceramics ceramics
• • food waste food waste
Adsorption Adsorption
• • clay clay
• • Fe/Mn Fe/ Mn Oxide Oxide
• • organic matter organic matter
→ → soil pollution soil pollution Cd Cd
2+2+Pb Pb
2+2+Cu Cu
2+2+Zn Zn
2+2+Metal Oxide Metal Oxide
Metal Hydroxide Metal Hydroxide
Al(Mn Al( Mn, Fe) , Fe)
ㆍㆍ M M
(z-(z-)+)+O O
Soil Soil Soil incineration
incineration
Environmental harmfulness of chloride
Municipal solid waste Municipal solid waste
incineration incineration
• chloride and salts NaCl NaCl
KCl KCl
CaCl CaCl
22ㆍㆍ 6H 6H
22O O
+ H + H
22O ⇒ O ⇒
Cl Cl
--Cl Cl
--• • Chloroform Chloroform
• • Chlorite Chlorite
• • Chlorate Chlorate
→ → synthesis synthesis poisonousness poisonousness poisonousness
Cl Cl
--• ionization
Volume-rate garbage disposal system
Removal of chloride
(L/S ratio : 10, Temp. : 20oC)
z chloride removal of above 85% within 30minutes
z residual chloride content of bottom ash : 0.2-0.3%R esidu al chlorid e content(%)
9 The sintering temperature of CCA clinker y Ordinary cement approximately 1,450oC y Ecocement approximately 1,350oC
9 Reduction of CO2emission
9 Application: Soil stabilization projects Calcium-chloroaluminate(11CaO·7Al2O3·CaCl2) cement
Characteristics of CCA cement
Soil stabilizer
Application field of CCA cement
2.5 2.7 Cl 1.10 5.75
0.21 1.65
3.47 23.29
2.21 8.78
1.07 10.27
24.70 Bottom ash I
Bottom ash D 2.20
MgO
0.98 TiO2
27.50 SiO2
1.20 ZnO
4.70 P2O5
2.50 Na2O
9.48 Fe2O3
2.00 K2O
25.49 CaO
8.50 Al2O3
0.25 MnO Sample
Chemical composition of Municipal solid waste incineration bottom ash
(Unit : wt.%)
20 30 40 50 60
z
z
z z z
z
z z z z z
zz z z
z z
z
: larnite : quartz
: calcite : C11A7CaCl2 : lime z
1,000oC
800oC
600oC
400oC
200oC
Int.
2θ
20 30 40 50 60
z
zz z z
z
z z
z z z
z z z
: lime
: larnite
: C11A7CaCl2
: quartz
zz z z
z z
z
: calcite z
1,000oC
800oC
600oC
400oC
200oC
Int.
2θ
(a) (b)
Synthesis of calcium chloroaluminate : above 1,000
oC
XRD patterns of (a) bottom ash I and (b) bottom ash D with various temperatures
ND 0.055
0.011 0.065
ND 0.030
1 20
ND ND
0.007 0.030
ND 0.012
28
0.005 3
0.3 1.5
3 1.5
Environmental criteria
Hg Pb
Cd As
Cu Cr
0.011 0.031 0.027 0.037 0.028 0.03
ND 0.041 0.015 0.027 0.011 0.028 0.037 0.028 ND 0.010
Concentration of heavy metal in leaching (ppm)
ND 0.035
0.005 0.054
ND 28
ND 0.034
0.014 0.063
ND 28
ND 0.007
0.008 0.054
ND 28
ND ND
ND ND
ND 28
ND ND
ND 0.050
ND 28
ND 0.010
0.005 0.022
ND 28
ND 0.046
ND 0.067
ND 28
ND ND
ND ND
ND 28
1 1 1 1 1 1 1 1
Curing time(day)
ND ND ND ND ND ND ND ND
0.055 0.036 0.017 0.010 0.041 0.025 0.022 ND
0.055 0.066 0.048 0.057 0.069 0.056 0.032 ND
ND ND ND 0.003
ND ND 0.004
ND
0.007 13
0.011 11
0.009 9
0.008 7
0.013 5
0.013 3
ND 0
0.010 15
Additive ratio of CCA(%)
Leaching of heavy metals from manufactured cement
z It satisfies the environmental standard and regulation
Solidification & stabilization of heavy metals
in MSWI bottom ash
• heavy metals and its compound
• • battery battery
• • vinyl vinyl
• • ceramics ceramics
• • food waste food waste
Adsorption Adsorption
• • clay clay
• • Fe/Mn Fe/ Mn Oxide Oxide
• • organic matter organic matter
→ → soil pollution soil pollution Cd Cd
2+2+Pb Pb
2+2+Cu Cu
2+2+Zn Zn
2+2+Metal Oxide Metal Oxide
Metal Hydroxide Metal Hydroxide
Al(Mn Al( Mn, Fe) , Fe)
ㆍㆍ M M
(z-(z-)+)+O O
Soil Soil Soil incineration
incineration
Environmental harmfulness of chloride
Municipal solid waste Municipal solid waste
incineration incineration
• chloride and salts NaCl NaCl
KCl KCl
CaCl CaCl
22ㆍㆍ 6H 6H
22O O
+ H + H
22O ⇒ O ⇒
Cl Cl
--Cl Cl
--• • Chloroform Chloroform
• • Chlorite Chlorite
• • Chlorate Chlorate
→ → synthesis synthesis poisonousness poisonousness poisonousness
Cl Cl
--• ionization
Volume-rate garbage disposal system
Aging of Bottom Ash for stabilization of heavy metals
X X Objectives Objectives
y Stabilization of soluble salts
y Stabilization of hydrogen-forming metals (such as aluminum) y Proper maintenance of moisture
y Control of pH by carbonization reaction and stabilization of heavy metals y Time requirement for 3-6 months
X U.S
y ageing for 60 days for using as aggregates of concrete y ageing for 30 days for using as pavement materials X France
y ageing for 3-6 months X Germany
y ageing for 3 months for recycling of bottom ash X England
y ageing for 3-6months for using as aggregates of concrete MM••(OH)(OH)nn
MMxx++
(At 850℃, about pH 12) (At 850
(At 850℃℃,,about pH 12) about pH 12)
M•M•COCO33 M
M••OO
• Oxidation
••OxidationOxidation
M
M••(OH)(OH)nn CO CO22
••CarbonationCarbonation
(M: metal(Al, Fe, Cu etc)) (M: metal(Al, Fe, Cu etc))
M M••OO
HH22OO
•
•HydrolysisHydrolysis
Temperature
TemperatureTemperature pHpHpH
Volume
VolumeVolume
VolumeVolume
Temp & pHTemp & pH
Aging requirement of bottom ash for road materials
Stabilization/conversion of bottom ash during aging
••Ion solidification Ion solidification
•• CaSOCaSO44••1/2H1/2H22O + 1O + 111//22HH22O O
→→CaSOCaSO44••2H2H22OO Gypsum Gypsum
••αα--FeFe22OO3 3 →→FeOOHFeOOH
→
Ageing for several years Ageing for several years
- - Stable - Stable -
•
•CaO + HCaO + H22O →O →Ca(OH)Ca(OH)22 Calcium oxide
Calcium oxide PortlanditePortlandite
••CaSOCaSO44 + 1/2H+ 1/2H22O →O →CaSOCaSO44••1/2H1/2H22OO
••Dissolution of saltsDissolution of salts
Quenching of bottom ash Quenching of bottom ash
--Unstable -Unstable -
••Ion sIon solidification olidification
•
•Ca(OH)Ca(OH)22+ CO+ CO22 →→CaCOCaCO33 Portlandite
Portlandite CalciteCalcite
•
•FeFe33OO44→→γγ--FeFe22OO33→→αα--FeFe22OO3 3
••Expansion of aluminum Expansion of aluminum
Ageing for 3months
Ageing for 3months
- - Semi- Semi -stable & stable stable & stable - -
Cd
Cd
2+2+ CdCd
2+2+ CdCOCdCO
33Pb
Pb
2+2+Pb
Pb2+2+Cu
Cu
2+2+Cu
Cu
2+2+Zn
Zn2+2+Zn
Zn
2+2+PbCO
PbCO33CuCO
CuCO
33 COCO
22CO
CO22CO
CO22 COCO
22ZnCO
ZnCO33Cd
2++ CO
2→ CdCO
3Cd Cd
2+2++ CO + CO
22→ → CdCO CdCO
33Zn
2++ CO
2→ ZnCO
3Zn Zn
2+2++ CO + CO
22→ → ZnCO ZnCO
33Pb
2++ CO
2→ PbCO
3Pb Pb
2+2++ CO + CO
22→ → PbCO PbCO
33Cu
2++ CO
2→ CuCO
3Cu Cu
2+2++ CO + CO
22→ → CuCO CuCO
33Low s olub ility Low s olub ility
K K
spsp=2.6× =2.6 ×10 10
-1-1K K
spsp=3.8× =3.8 ×10 10
-2-2K K
spsp=7.5× =7.5 ×10 10
-1-1K K
spsp=2.4× =2.4 ×10 10
-1-1Carbonation for Fixation of Metals in MSWI Bottom Ash
0 2 4 6 8 10 12 14
1ppm
Cr3+
Fe2+
As3+
Pb2+
Zn2+
Cd3+
Cu2+
Hg2+
Fe3+
Cr3+
0
-2
-4
-6
-8
-10 log m M(M/L)
pH 2.4 10-1
4.3 10-1 5.2 10-1
3.0 10-2
ZnCO3 ZnS
Zn(OH)2 Zn3(PO4)2
Zn+2
7.5 10-1 1.6 10-11
1.1 10-2 3.1 10-3
CuCO3 CuS
Cu(OH)2 Cu3(PO4)2
Cu+2
1.2 10-11 8.1 10-3
Cu2S Cu+ CuOH
1.3 10-21 2.4 10-1
HgS Hg(OH)2
Hg+2
5.4 10-11 1.1
Hg2CO3 Hg2S
Hg2HPO4 Hg2+2
2.6 10-1 2.5 10-9
4.1 10-2 1.1
CdCO3 CdS
Cd(OH)2 Cd3(PO4)2
Cd+2
3.8 10-2 2.1 10-9
7.1 10 2 2.3 10-4
PbCO3 PbS
Pb(OH)2 Pb3(PO4)2
Pb+2
2.3 10-1 3.1 10-2
2.3
MnCO3 MnS
Mn(OH)2 Mn+2
6.3 10-4 2.5 10-7
Cr(OH)3 CrPO4
Cr+3
7.1 10-7 Cr(OH)2 Cr+2
Carbonate Carbonate Sulfide
Sulfide Hydroxide
Hydroxide Phosphate
Phosphate IonIon
Solubility of heavy metals hydroxides Solubility product constant of heavy
metals compount(25℃)
10.2 11.8
12.0 12.2
12.5 bottom ash D
9.4 11.1
11.3 11.5
12.3 bottom ash I
6 3
2 1
0
Aging period(month) Samples
3.0 0.3
1.5 3.0
1.5 Leaching criteria of Korea
0.06 ND
ND 1.731.73
0.03 9.4
6
0.06 ND
0.05
4.414.410.15 12.5
bottom ash D 0
0.05 ND
0.02
1.81.8
0.10
10.2 6
0.08 ND
0.06 3.26
3.26 0.13
12.3 bottom ash I 0
Pb Cd
As
CuCr
Concentration (mg/L) Aging period pH
(month) Sample
Leaching concentration of heavy metals pH change
Stabilization of heavy metals during aging
bottom ash I
bottom ash D
3.0 0.3
1.5 3.0
1.5 Criteria of leaching
0.55 ND
ND 3.40
0.50 12.2
0.34 0.150
0.6 3.68
0.0043 6.8
0.84 0.710
4.4 32.37
1.80 4.0
1.73 0.976
27.6 141.75
12.94 1.8
0.40 ND
ND 3.25
9.4 0.48
Leached heavy metals(
Leached heavy metals(ppmppm, As : ppb), As : ppb) pHpH
2.83 ND
ND 5.26
0.50 13
0.59 0.005
0.6 3.40
0.27 8.3
PbPb CdCd
AsAs CuCu
CrCr
3.0 0.3
1.5 3.0
1.5 Criteria of leaching
5.49 ND
ND 3.49
13 0.3
0.67 ND
ND 2.45
0.3 12
0.25 ND
ND 1.77
0.03 9.1
0.51 0.0016
1.6 1.67
7.7 ND
0.44 0.34
3.3 2.97
ND 5.7
0.90 0.90
5.4 17.12
0.30 3.8
1.98 1.26
30.0 94.45
2.3 3.57
Pb Pb Cd
Cd As
As Cu
Cu Cr
Cr
Leached heavy metals(
Leached heavy metals(ppmppm, As : ppb), As : ppb)
pHpH
Leaching of heavy metals with pH
Stabilization of heavy metals by carbonation
1.5 0.3
1.5 3.0 3.0
criteria
ND ND ND ND ND As
0.2 0.1 0.1 0.2 0.2
Cr Cd
Pb Cu
ND 0.7
1.3 8
ND 1.1 0.5
9
ND 1.3 0.5
10
ND 0.5
4.0 11
ND 0.6
5.1 12.3
Concentration of leached heavy metals(mg/L) pH
Concentration of leached heavy metals with pH change by carbonation
z pH 10-8 satisfied the environmental standards and regulation
Leached Cu concentration with carbonation time and CO
2flow rate
(temp. : 20oC, L/S ratio : 10(v/w))
z Cu leaching by carbonation
- diminishment above 50%(3.7ppm Æ 1.3ppm)
0.05 0.05 0.100.10 0.15 0.15
Comparison of natural weathering and carbonation
10.2 11.8
12.0 12.2
12.3 D bottom ash
9.4 11.1
11.3 11.5
11.7 I bottom ash
6 3
2 1
0
Aging period(month) Samples
0.06 ND ND 1.731.73
0.03 9.4
6
0.06 ND 0.05 4.41
4.41 0.15
12.5 D bottom ash 0
0.08 ND 3.26 0.06
3.26 0.13
12.3 I bottom ash 0
Pb Cd As Cu
Cr
Concentratiom(mg/L) Aging period pH
(month) Sample
Leaching of heavy metals Natural weathering Natural weathering pH
Stabilization period of heavy metals
1.5 0.3
1.5 3.0
3.0 criteria
ND ND ND ND ND As
0.2 0.1 0.1 0.2 0.2
Cr Cd
Pb Cu
ND 0.7
1.3 8
ND 0.5
1.1 9
ND 0.5
1.3 10
ND 0.5
4.0 11
ND 0.6
5.1 12.3
Leached heavy metals(mg/L) pH
Carbonation Carbonation
Natural weathering
: 3-6months
Carbonation :
Within 2 hours
Characteristics of wastewater after treatment
<40 57.3
COD
5.8-8.6
<0.3
<0.1
<0.003
<3,000
<5
<400
<15 criterion
<10
<0.5
<1
<0.5
<1
<0.005
<3
<5 criterion
<0.1
<10
<30
<1 M* : <5 O **: <30
<5
<8
<60 criterion
9.5 ND ND ND
<2 0.56
42 0.30 Waste
water
pH PCE TCE PCB E.Coli
ABS Color
F Sample Items
0.02 ND 0.09 0.001
ND ND 0.05 0.03 Waste
water
Mn Cr Pb As Organophosph
orus Hg Cu Zn
Sample Items
ND 0.05 42.5 0.002
ND ND 7.03 12.1 waste water
Cd Fe BOD
CN N-hexane
extracts Phenol
T-P T-N
Sample Items
* : Mineral oil
** : Oil and fat of animals and plants
z Quality of wastewater satisfies the environmental standard and regulation
Carbonation process for capsulation
1. CO2diffusion
2. Permeation CO2to solid waste 3. Dissolution of CO2(g)(CO2(aq)) 4. Hydration of CO2(aq)to H2CO3. 5. Ionization of H2CO3(pH 8) 6. Decomposition of C3S and C2S 7. Nucleation of CaCO3
8. Precipitation of Calcite, vaterite
9. Secondary carbonation(S-H, CaCO3 등)
Waste Gas phase
Pore fluid
Solid phases CaCO
3
CO2 1
8 9
6
Calcium silicate
2
3 4 5
7
SH
Increase of volume/gravity : Ca(OH)2+ CO2Æ CaCO3+ H2O : 11.8%
(Ca(OH)2gravity(volume) : 2.24g/mol(33.0ml), CaCO3gravity(volume) : 2.71(36.9ml)
Decrease of porosity, enhancement of strength : formation of C-S-H gel, Calcite, ettringite
Formation of stable heavy metal compounds - Pb : formation of PbCO3
- Cd : formation of hydroxicarbonates - Ni, Co : substitution of Ca in C-S-H - Ba : formation of BaCO3, BaSO4
CO2diffusion
Carbonated zone
Unaltered wasteform Heavy metals
Heavy metals
Carbonation process
Capsulation effect : immobilization of heavy metals
Decrease of pH : pH of lowest solubility for metal hydroxides(pH 8-9.5)
Before carbonation
After carbonation
Chemical composition of bottom ash
43 35 33 24 22 28 12 Cd
137 135 167 145 171 133 112 Ni
985 1075 1202 1412 1849 880 618 Pb
394
1602Under 0.15
378
18180.15-0.3
489
25920.3-0.6
442
22990.6-1.18
496
35111.18-2.36
327
25922.36-4.75
333
2938Over 4.75
Cr
CuContent of heavy metals (mg/kg) size (mm)
ppm Size (mm)
11.74 22
171 496
1849 3511
4.35 0.6
4.55 17.4
1.18-2.36
Cd pH Ni
Cr Pb
Cu Na(%)
Zn(%) Al(%)
Ca(%)
The content of Cu and Pb in bottom ash
Chemical composition and pH in fresh and carbonated bottom ash
Carbonation reactor
Reactor of carbonation process
• CO
2flow rate: 1.0 L/min
• Water content : 20%
• Liquid/Solid: 10
• CO
2flow rate: 1.0 L/min
z Condition of wet carbonation z Condition of dry carbonation
• Dry reactor
• Wet reactor
• Dry reactor
• Wet reactor
• CO2gas
• Gas flowmeter
Leaching amount of Heavy metals & pH according to wet/dry carbonation
9.02 7.96
11.74 pH
<0.01
<0.01 1.54(3.0)
Pb (ppm)
<0.01 0.01
3.26(3.0) Cu (ppm)
bottom ash after dry carbonation bottom ash after wet
carbonation fresh bottom ash
(St. Limited)
z Leaching amounts of Cu and Pb decrease with the wet/dry carbonation
z pH of MSWI bottom ash also decreases via the wet/dry carbonation
0.000154 0.000401
0.00046 pore size (cm
3/g)
0.3317 0.7587
0.1047 volume (m
2/g)
2.3892 3.5269
1.2233 BET surface area
(m
2/g)
bottom ash after dry carbonation
bottom ash after wet carbonation
fresh bottom ash
Change in surface area, volume, and pore Size of MSWI bottom ash via wet/dry carbonation
z Surface area, and volume increase with the wet/dry carbonation z Pore size decreases via the wet/dry carbonation
z In particular, the pore size is drastically decreased by dry carbonation
Surface Analysis of MSWI bottom ash with SEM
without carbonation with wet carbonation with dry carbonation
•Products (Calcium carboantes)
•Capsulation effect : immobilization of heavy metals
• Wet carbonation < Dry carbonation
Carbonated zone
Unaltered wasteform Heavy metals
Heavy metals
Stability of Heavy metals
Wet carbonation system with dry carbonation
• Carbonation process effects the pH of solution : 11.9 →7.9
• Change in solubility of Cu and Pb
• Leaching amounts of Cu and Pb decrease
• Carbonation process forms carbonates on the surface of MSWI bottom ash
• Capsulation effect
• Leaching amounts of Cu and Pb decrease
A Long term stability
Wet carbonation < Dry carbonation
Stabilization of heavy metals Stable properties
Weathering Problems in recycling of bottom ash
• leaching of Cu, Pb, Cd
• instable physical properties (expansion)
• high chloride content
Need of long period for 3
Need of long period for 3-6months-6months Lack of stockpile
Lack of stockpile
Low effect of chloride removal Low effect of chloride removal
Pretreatment using in U.S and European countries
-
-Stabilization of heavyStabilization of heavy metals
metals
--Stable propertiesStable properties
--Shortening of stabilizationShortening of stabilization period
period
--chloride removalchloride removal
Weathering effect
CO2 gas
Developing technology
1
2 3
1
2 3
rotation type 3
agitator type treatment of wastewater 2
1
Pilot scale(60L)
Lay-out of pilot plant
Magnetic Magnetic separator
separator FeedFeed hopper hopper
Non Non--ferrousferrous
separator separator
Rotary Rotary kilnkiln
Coarse aggregate silo Coarse aggregate silo
Fine aggregate silo Fine aggregate silo
Vibrating Vibrating screen screen Vibrating
Vibrating screen screen
FeedFeed hopper hopper Incineration
Incineration plant plant
Trommel Trommel
Wastewater Wastewater treatment treatment
Equipment for Fixation of Equipment for Fixation of heavy metals & Removal of heavy metals & Removal of ClCl
Capacity : 100kg/hr
• Clinkering Reaction • Hydration Reaction
Solidification of Heavy metals in Cement Process
Solidification of Heavy metals in Cement industry Solidification of Heavy metals in Cement industry
Future works of emerging technologies of recycling for inorganic wastes
• Clinkering Reaction • Hydration Reaction
Solidification of Heavy metals in Cement Process
Solidification of Heavy metals in Cement industry Solidification of Heavy metals in Cement industry
Future works of emerging technologies of recycling for inorganic wastes
Clinkering Reaction
2CaCO3+CA→C3A+CO2 2CaCO3+SiO2→C2S+CO2 CaCO3→CaO+CO2
2CaO+SiO2→C2S CaO+C2S →C3S 2CaO+C2F→C4AF Breakdown of clays and iron ore
350 ∼ 800 ℃
Carbonation of SiO2+CaO 900 ∼ 1200 ℃ Carbonate dissociation
800 ∼ 1000 ℃ Release of SiO2Al2O3of clays
700 ∼ 900 ℃
Liq. formation 1200 ∼ 1280 ℃
C3S formation 1300 ∼ 1380 ℃ Kaoline+CaCO3→2C2S+CA+H2O+5CO2
2CaCO3+Fe2O3 →C2F+CO2
▶C3S : Tricalcium Silicate- Alite
(Ca0.98Mg0.01Al0.0067Fe0.0033)3(Si0.97Al0.03)O5
▶C2S : Dicalcium Silicate- Belite Ca2Fe0.05Al0.05Si0.90O3.95
▶C3A: Aluminate Phase
K0.03Na0.06Ca2.76Mg0.08Ti0.01)(Fe0.22Al1.60Si0.18)O6
▶C4AF : Ferrite Phase- Celite Ca2AlFe0.6Mg0.2Si0.15Ti0.05O5
■ Main minerals of clinker
■ Clinkering reaction in kiln
Tricalcium silicate (Alite)
Solidification of heavy metals in Clinkers
(a) (b)
Substitution of Si4+ion by Ti4+in tetrahedral site [B. V. volkonskkii, et al., Tsement 6 (1974) 17-19]
Substitution of Zn2+for Ca2+ site
[I. Odler et al., J. Am. Ceram. Soc., 63 (1980) 519-522]
Substitution of Cr3+for Ca2+ site
[A. I. Boykova, Dokl. Chem. Techonl., 156 [6] (1964) 90 -92]
Twin Plane 100
Twin Plane 100
C a
Calcium silicate networksretain large amount ofCd, Pb, Crand Zn
[M. A. Trezza et al., Cem. Con. Res. 30 (2000) 137-144]
Dicalcium silicate (Blite)
: Ca106Mg2(Na0.25K0.25Fe0.5)(Al2Si34)O180 : Ca87MgAlFe(Na0.25K0.25)(Al3Si42)O180
Alitecontaining small amounts of iron, magnesium, potassium, sodium, aluminumand titaniumoccurs in Portland cement
Bilte
Biltecontaining small amounts ofmagnesium, aluminum, iron, magnesium, aluminum, iron, sodium
sodium andpotassiumpotassiumoccurs in Portland cement clinker