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Treatment Technologies of Fly Ash from WtE Incineration in Japan
Hirofumi SakanakuraNational Institute for Environmental Studies (NIES)
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2020-10-07IEA Bioenergy
Webinar: Valorisation of fly ash from Waste-to-Energy
MSW treatment stream in Japan
In addition to the above figures, 1.5% of "fuel", 0.5% of "compost", 0.03% of "livestock feed", and 0.2% of "methane fermentation". As a result, partially incinerated and partially landfilled.
Combustibles Incineration and Melting
Ash and Slag
(Combustibles)
Landfill76%
3%
7%
Recycle
10%
Total: 43 million tons in FY 2017
Total 9%Total 79%
Incombustibles
Resource wastes
Crush and Sorting(Incombustibles)
Regional collectionRecycle5%
5%
Bulky wastes
7%
6%
5%
Total 17%
1%
1%
Mixed waste, Incombustibles
3%
2Ministry of the Environment
Factors affecting characteristics of ashes
3
Quenching
Small particlesEvaporates• Acid gas• Low B.P. Heavy metals
Fly ash with APC Residue
Neutralization Adsorption Filtration
Coagulation
Lime (Excessive)Activated Carbon
Landfill orRecycling
Bottom ash
Gas cooling(Boiler, water)
Landfill or Recycling
High pH, Ca, Cl, heavy metals
High pH, wide range of particle [email protected]
Discharge from bottom outlet
Treatment Technologies of Fly Ash in Japan
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ThermalTreatment
Stabilizationand
Solidification
- Melting (Vitrification)- Sintering- Raw material of cement
- Chemical stabilization- Organic agent- Inorganic agent
- Cement solidification
Fly ash
Landfill
Construction materialSecondary fly ash and metal (Raw material of smelting)
内津山北最終処分場
エコパークかごしま
大阪沖埋立処分場 岡崎市北部一般廃棄物処分場
浜松市平和最終処分場
写真：各最終処分場のホームページから
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Typical municipal waste landfills (controlled landfill) in Japan
Regulation on Fly Ash• Fly ash is designated as a specially controlled waste
(1991); fly ash must be treated to meet the waste landfill criteria– Heavy metals and inorganics (Pb, Cd, Cr(VI), Hg, As, Se)
• Evaluation: Leaching test – Mixing with pure water under L/S 10 for 6 hours and filtration
– VOC, Fertilizers• Evaluation: Leaching test
– Dioxins• Evaluation: Total content
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Sieve 0.5-5.0 mm
1
Leachant (water)
3
Weigh > 50 g
2
Japanese Environmental Agency Notification No.13, 1973 (JLT13)
Add water L/S = 10 (L/kg)
4
5
Shaking 6 hours
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Centrifugation
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Liquid-solid separationusing 1.0 ummembrane filter
Leaching Test
Env. Standard for Soil*
(Leaching test)
Soil Contamination Countermeasure Act Landfill
(Leaching test)Leaching test Acid extraction
Test method JLT46 (1991) MOE Ntf. No.18 (2003)
MOE Ntf. No.19 (2003) JLT13 (1973)
Unit mg/L mg/L mg/kg mg/LCadmium
LeadCr(VI)
ArsenicTotal-HgAlkyl-HgSeleniumFluorine
Boron
0.003**0.010.05
0.01***0.0005
Not detected0.010.81
0.0030.010.050.01
0.0005Not detected
0.010.81
4515025015015-
15040004000
0.090.31.50.3
0.005-
0.3--
* Natural source, stock yard and waste landfill are excluded** Agriculture field: 1 mg/kg-rice*** Rice field: 15 mg/kg-soil
Environmental Standard for Soil, Criteria in Soil Contamination Countermeasure Act, and Landfill Criteria (Metals)
• Immobilize heavy metals in ash by chemical agents • Various types
• Organic chelator (Dithiocarbamate, Piperazine)• Phosphoric acid• Iron hydroxide• etc.
• In Japan, organic chelators are the mainstream for landfill disposal, but there are doubts in long-term stability.
• Long-term COD loads and ecotoxicological effects are also suspected.
Chemical stabilization
9http://www.fujisash.co.jp/hp/business/environment/dest/dust/
to Landfill only
Cement Solidification• Mixing fly ash with cement and
water• The treated ash is not hard enough
to have strength. • Not an instant reaction. The
leaching of heavy metals decreases slowly.– Better to think that heavy metals are
fixed by the chemical reaction of cement.
10http://www.fujisash.co.jp/hp/business/environment/dest/dust/
to Landfill only
Actual situation of fly ash treatment
11
0
100
200
300
400
500
600
700
Mel
ting
Cem
ent s
olid
ifica
tion
Chem
ical
sta
biliz
atio
n
Oth
ers
Mel
ting
and
Che
mic
al
Mel
ting
, Cem
ent,
Chem
ical
Cem
ent,
Chem
ical
Chem
ical
, Oth
ers
Oth
er c
ombi
nati
on
No
trea
tmen
t
Single Combination
Num
ber
of fa
cilit
ies
Stoker Fluidized bed Gasification-melting Others
?
13 41 614 32 15 10 133 25 9 88
980 in total
“No treatment” probably include “Raw material of cement” and “Melting at private plants”.As of FY2017Ministry of the Environment
Melting (Vitrification)
Takuma corporation
• Ashes are melted at high temperature and cooled down to obtain “MSW Slag”
• Feeds: BA and FA. Characteristics of slag from ash melting direct melting and are basically similar.
• Slag is recycled as construction material.
• About 540,000 tons of slag (Feed: BA, FA, raw MSW) are recycled from about 200 facilities.
• By products of Metal and Secondary fly ash can be recycled as metal resources.
Plasma arc melting
Surface meltingMetal
FeCu
MSW Slag
SiO2, Al2O3, CaO
1250-1400oC
1300-1400oC
Ash
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Fly ash
Recycling
JIS A 5031 “Melt-solidified slag aggregate for concrete”
Coverage: Precast concrete Coarse aggregate (MG20-05, MG20-15,
MG15-05) Fine aggregate (MS5, MS2.5, MS1.2, MS5-0.3)
Quality General Environmental Safety (Leaching and
Content) Chemical composition (CaO, S, SO3, Fe) Expansiveness Physical properties (Density, Water
absorption, Stability, Solid content, and Amount of minute grain)
Alkali silica reactiveness Granularity and fineness modulus
JIS A 5032 “Melt-solidified slag material for road construction”
Coverage: Hot asphalt mixture and base material For hot asphalt mixture (SM-20, -13, -5,
FM-2.5) For base course material (MM-40, -30, -25) For subbase course material (CM-40, -30, -
20)
Quality Externals Environmental Safety (Leaching and
Content) Physical properties (Granularity, Density,
Water absorption, and Abrasion loss) Corrected CBR (for base and subbase only)
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Leaching Test for SlagJIS K 0058-1 clause 5 Mixing Blade Method
Vessel
Sample
Sample pretreatment:- Granular material: without size reduction- Monolith material:
Concrete: 100 mm-D x 200 mm-H test pieceAsphalt: 100 mm-D x 63.5 mm-H test pieceA product 5 kg or less: as it is
L/S = 10 L/kg, Leachant: pure waterStir 200 times/min for 6 hours
Propeller
Raw material of cement
15Taiheiyo Cement Corporation
Bottom ash
Fly ash
MSW
Washing process
Sorting process
Cement production
Since the components of the ashes are close to cement, they can be accepted as cement raw material in ~1% of the total feed materials.Pretreatment: Bottom ash : removal of big sizes, metals and crushing. Fly ash : washing out of chlorine.About 380,000 tons/year (BA+FA) are recycled in almost all (~30) cement factories (FY2017).
Recycling
Raw material of metal smelting• Fly ashes generated from melting furnace are
accepted as a raw material of metal smelting.– They have a high concentration of metals such as Zn (~5%)
and Pb (~1%)– There are several smelting companies in Japan that accept
metal-rich waste including fly ashes.– Fly ash from incinerators is also accepted (but not the
main target).
• Municipalities pay the processing fee to the metal smelting companies.
• Metal smelting companies perform pretreatmentsuch as desalination before putting them into the furnace.
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Ca
Cl
NaK
SZn
PbOthers
Element composition of Fly ash from melting furnace
Recycling
Fly ash can/should be recycled?• In Japan, recycling of fly ash is limited to thermal technologies;
• Melting (vitrification); Slag to construction. Metal and fly ash to smelting• Cement raw material
– The amount recycled would be limited compare to bottom ash.• High content of heavy metal and salt, resulting high cost
– Other stream is difficult• Designated as specially controlled waste due to high concentration and releasability of heavy
metals. • Recycling in construction without removing heavy metals should be avoided.
• Most fly ashes are landfilled after chemical treatment to (apparently) stop the elution of heavy metals using chelating agents.– However, organics eluted from the agent has become a new problem in landfill. Long-
term stability is also worried.
• I'm looking for a clue to solve the fly ash problem, and I wish information exchange with you for future.
17
![Welcome []...10 An electromagnetic overband separator removes metal from the ash. The metal is delivered to local companies for recycling. 11 Ash from the incineration process goes](https://img.pdfslide.us/doc/110x75/5f2cf8f969a71e25b05d3709/welcome-10-an-electromagnetic-overband-separator-removes-metal-from-the.jpg)
