Residual chloride content(%)

58  Download (0)

전체 글

(1)

Solidification/stabilization of hazardous materials for recycling the industrial wastes

2006. 4 Ji-Whan Ahn

Korea Institute of Geoscience and Mineral Resource

(2)

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

(3)

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

(4)

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

(5)

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 incinerator

above 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

(6)

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

(7)

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.

(8)

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

(9)

A Pretreatment for Cl Removal and Stabilization of Heavy Metal to

Recycle Municipal Solid Waste Incineration Bottom Ash

(10)

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)

(11)

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

(12)

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)

(13)

Removal & Solidification of chloride in MSWI bottom ash

- Synthesis of calcium chlorine-aluminate cement (CCA cement) -

(14)

• 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)

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

22

6H 6H

22

O O

+ H + H

22

O ⇒ O

Cl Cl

--

Cl Cl

--

• • Chloroform Chloroform

• • Chlorite Chlorite

• • Chlorate Chlorate

→ → synthesis synthesis poisonousness poisonousness poisonousness

Cl Cl

--

• ionization

Volume-rate garbage disposal system

(15)

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(%)

(16)

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

(17)

Soil stabilizer

Application field of CCA cement

(18)

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

„

„ „

„

Œ

Œ‰

‰

‰ Œ

Œ

Œ

Œ

„

„ „ „ „

„ „ „

„

„ „

„ 





 z

z

z z z

z

z z z z z

zz z z

z z

z

: larnite : quartz ‰

: calcite „: C11A7CaCl2Œ : lime z

1,000oC

800oC

600oC

400oC

200oC

Int.

2θ

20 30 40 50 60

„

„

‰

‰

„

„

„ „

„ „

„

„

„ z „

Œ

Œ

„

„

„

„

‰

Œ

Œ

Œ

Œ

zz z z

z

z z

z z z

z z z







: lime

Π: 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

o

C

XRD patterns of (a) bottom ash I and (b) bottom ash D with various temperatures

(19)

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

(20)

Solidification & stabilization of heavy metals

in MSWI bottom ash

(21)

• 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)

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

22

6H 6H

22

O O

+ H + H

22

O ⇒ O

Cl Cl

--

Cl Cl

--

• • Chloroform Chloroform

• • Chlorite Chlorite

• • Chlorate Chlorate

→ → synthesis synthesis poisonousness poisonousness poisonousness

Cl Cl

--

• ionization

Volume-rate garbage disposal system

(22)

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

ƒTemperature

ƒTemperatureƒTemperature ƒpHƒƒpHpH

ƒVolume

ƒ

ƒVolumeVolume

VolumeVolume

Temp & pHTemp & pH

Aging requirement of bottom ash for road materials

(23)

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 - -

(24)

Cd

Cd

2+2+ Cd

Cd

2+2+ CdCO

CdCO

33

Pb

Pb

2+2+

Pb

Pb2+2+

Cu

Cu

2+2+

Cu

Cu

2+2+

Zn

Zn2+2+

Zn

Zn

2+2+

PbCO

PbCO33

CuCO

CuCO

33 CO

CO

22

CO

CO22

CO

CO22 CO

CO

22

ZnCO

ZnCO33

Cd

2+

+ CO

2

→ CdCO

3

Cd Cd

2+2+

+ CO + CO

22

→ → CdCO CdCO

33

Zn

2+

+ CO

2

→ ZnCO

3

Zn Zn

2+2+

+ CO + CO

22

→ → ZnCO ZnCO

33

Pb

2+

+ CO

2

→ PbCO

3

Pb Pb

2+2+

+ CO + CO

22

→ → PbCO PbCO

33

Cu

2+

+ CO

2

→ CuCO

3

Cu Cu

2+2+

+ CO + CO

22

→ → CuCO CuCO

33

Low s olub ility Low s olub ility

K K

spsp

=2.6× =2.6 ×10 10

-1-1

K K

spsp

=3.8× =3.8 ×10 10

-2-2

K K

spsp

=7.5× =7.5 ×10 10

-1-1

K K

spsp

=2.4× =2.4 ×10 10

-1-1

Carbonation for Fixation of Metals in MSWI Bottom Ash

(25)

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℃)

(26)

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

4.414.41

0.15 12.5

bottom ash D 0

0.05 ND

0.02

1.8

1.8

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

Cu

Cr

Concentration (mg/L) Aging period pH

(month) Sample

Leaching concentration of heavy metals pH change

Stabilization of heavy metals during aging

(27)

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

(28)

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

(29)

Leached Cu concentration with carbonation time and CO

2

flow 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

(30)

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

(31)

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

(32)

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

(33)

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

1602

Under 0.15

378

1818

0.15-0.3

489

2592

0.3-0.6

442

2299

0.6-1.18

496

3511

1.18-2.36

327

2592

2.36-4.75

333

2938

Over 4.75

Cr

Cu

Content 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

(34)

Carbonation reactor

Reactor of carbonation process

• CO

2

flow rate: 1.0 L/min

• Water content : 20%

• Liquid/Solid: 10

• CO

2

flow 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

(35)

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

(36)

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

(37)

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

(38)

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

(39)

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

(40)

1

2 3

1

2 3

rotation type 3

agitator type treatment of wastewater 2

1

Pilot scale(60L)

(41)

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

(42)

• 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

(43)

• 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

(44)

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

(45)

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

수치

Updating...

참조

관련 주제 :