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BENEFICIAL USE OF COAL COMBUSTION PRODUCTS

AN AMERICAN RECYCLING SUCCESS STORY

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The American Coal Ash Association was established in 1968 as a trade organization devoted to recycling the materials created when we burn coal to generate electricity. Our members comprise the world’s foremost experts on coal ash (fly ash and bottom ash), and boiler slag, flue gas desulfurization gypsum or “synthetic” gypsum, and other “FGD” materials captured by emissions controls. While other organizations focus on disposal issues, ACAA’s mission is to advance the management and use of coal combustion products in ways that are: environmentally responsible; technically sound; commercially competitive; and supportive of a sustainable global community.

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BENEFICIAL USE OF COAL COMBUSTION PRODUCTS

AN AMERICAN RECYCLING SUCCESS STORYCoal combustion products – often referred to as “coal ash”– are solid materials produced when coal is burned to generate electricity. There are many good reasons to view coal ash as a resource, rather than a waste. Using it conserves natural resources and saves energy. In many cases, products made with coal ash perform better than products made without it.

As coal continues to produce approximately one-third of the electricity generation in the United States, significant volumes of coal ash are produced. Since 1968, the American Coal Ash Association has tracked the produc-tion and use of all types of coal ash. These surveys are intended to show broad utilization patterns and ACAA’s data have been accepted by industry and numerous gov-ernment agencies as the best available metrics of benefi-cial use practices.

Fifty-eight percent of the coal ash produced during 2018 was recycled—down from 64 percent in 2017, but marking the fourth consecutive year that more than half of the coal ash produced in the United States was beneficially used rather than disposed. Use of coal fly ash in concrete declined 11 percent to 12.5 million tons. Concrete producers and consumers indicated a desire to use more fly ash, but several regional markets were affected by shifting supply dynamics associated with closures of coal-fueled power plants. Utilization of a key “non-ash” coal combustion product returned to expected levels. Use of synthetic gypsum in panel products (i.e., wallboard) declined 23 percent to 12.3 million tons. This volume is consistent with utilization volumes in the 2014-2016 period following a 2017 in which users took advantage of an opportunity to increase stockpiles of gypsum for raw material.

All CCPs Production and Use with Percent

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Fly ash is a powdery material that is captured by emissions control equipment before it can “fly” up the stack. Mostly comprised of silicas, aluminas and calcium compounds, fly ash has mechanical and chemical properties that make it a valuable ingredient in a wide range of concrete products. Roads, bridges, buildings, concrete blocks and other concrete products commonly contain fly ash.

Concrete made with coal fly ash is stronger and more durable than concrete made with cement alone. By reducing the amount of manufactured cement needed to produce concrete, fly ash accounts for approximately 12 million tons of greenhouse gas emissions reductions each year.

Other major uses for fly ash include constructing structural fills and embankments, waste stabilization and solidification, mine reclamation, and use as raw feed in cement manufacturing.

Fly Ash

Bottom ash is a heavier, granular material that is collected from the “bottom” of coal-fueled boilers. Bottom ash is often used as an aggregate, replacing sand and gravel. Bottom ash is often used as an ingredient in manufacturing concrete blocks.

Other major uses for bottom ash include constructing structural fills and embankments, mine reclamation, and use as raw feed in cement manufacturing.

Bottom Ash

The American Road & Transportation Builders Association estimates coal fly ash use in roads and bridges saves $5.2 billion per year in U.S. construction costs.

Fly ash ranges in color from gray to buff depending on the type of coal.

Bottom ash is a granular material suitable for replacing gravel and sand.Bottom ash can be used in asphalt paving.

Fly Ash Production & Use 2000 – 2018

Bottom Ash Production & Use 2000 – 2018

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Power plants equipped with flue gas desulphurization (“FGD”) emissions controls, also known as “scrubbers,” create byproducts that include synthetic gypsum. Although this material is not technically “ash” because it is not present in the coal, it is managed and regulated as a coal combustion product.

Scrubbers utilize high-calcium sorbents, such as lime or limestone, to absorb sulfur and other elements from flue gases. Depending on the scrubber configuration, the byproducts vary in consistency from wet sludge to dry powdered material.

Synthetic gypsum is used extensively in the manufacturing of wallboard. A rapidly growing use of synthetic gypsum is in agriculture, where it is used to improve soil conditions and prevent runoff of fertilizers and pesticides.

Other major uses for synthetic gypsum include waste stabilization, mine reclamation, and cement manufacturing.

Synthetic Gypsum

Synthetic Gypsum Production & Use 2002 – 2018

Synthetic gypsum is often more pure than naturally mined gypsum.

More than half of the gypsum wallboard manufactured in the United States utilizes synthetic gypsum from coal-fueled power plants.

Synthetic gypsum applied to farm fields improves soil quality and performance.

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Boiler Slag – is a molten ash collected at the base of older generation boilers that is quenched with water and shatters into black, angular particles having a smooth, glassy appearance. Boiler slag is in high demand for beneficial use as blasting grit and roofing granules, but supplies are decreasing because of the retirement from service of older power plants that produce boiler slag.

Cenospheres – are harvested from fly ash and are comprised of microscopic hollow spheres. Cenospheres are strong and lightweight, making them useful as fillers in a wide variety of materials including concrete, paint, plastics and metal composites.

FBC Ash – is a category of ash from Fluidized Bed Combustion power plants. These plants reclaim waste coal for fuel and create an ash by-product that is most commonly used to reclaim abandoned surface mines and abate acid mine drainage. Ash from FBC power plants can also be used for waste and soil stabilization.

Other Products and Uses

New beneficial uses for coal ash are continually under development. Researchers and ash marketers are currently focusing heavily on the potential for harvesting ash that has already been disposed for potential beneficial use. There is also renewed interest in the potential for extracting strategic rare earth minerals from ash for use in electronics manufacturing.

New Uses on Horizon

Nearly 90 percent of all boiler slag is beneficially used.

Because of their high value, cenospheres – seen here in a microscopic view – are measured by the pound rather than by the ton.

This regional park was constructed with FBC ash on the site of a former waste coal pile.

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2018

CC

P C

ateg

orie

sFl

y A

shB

otto

m A

shB

oile

r Sla

gFG

D G

ypsu

mFG

D M

ater

ial W

etSc

rubb

ers

FGD

Mat

eria

lD

ry S

crub

bers

FGD

Oth

erFB

C A

sh

Tota

l CC

Ps P

rodu

ced

by C

ateg

ory

36,1

78,4

279,

197,

362

1,53

4,94

532

,783

,995

4,73

2,90

02,

154,

301

121,

126

15,5

71,8

24

Total CCP

s Used by

 Category

20,0

81,3

304,

350,

321

1,03

6,91

918

,337

,477

91,0

3649

8,53

20

15,0

45,2

25

1.   Co

ncrete/Con

crete Prod

ucts /G

rout

12,5

20,4

9258

2,01

00

235,

578

00

093

,555

13,4

31,6

35

2.   Blen

ded Ce

men

t/ Feed for C

linker

3,12

7,44

71,

218,

581

167,

996

1,86

5,27

90

00

5,58

56,

384,

889

3.   Flow

able Fill

83,7

610

00

00

00

83,7

61

4.   Structural Fills/Em

bankmen

ts1,

515,

590

1,32

0,43

90

1,73

5,00

80

00

04,

571,

036

5.   Ro

ad Base/Sub‐base

234,

798

160,

061

04,

978

01,

159

00

400,

997

6.

Soil

Mod

ifica

tion/

Stab

ilizat

ion

245,

197

2,07

00

00

00

024

7,26

7

7.

Min

eral

Fille

r in

Asph

alt

10,4

240

00

017

30

010

,597

8.

Snow

and

Ice

Con

trol

013

4,50

311

,018

00

00

014

5,52

1

9.

Blas

ting

Grit

/Roo

fing

Gra

nule

s0

27,1

4846

8,36

50

00

00

495,

513

10. M

inin

g Ap

plic

atio

ns53

0,44

40

020

,487

00

014

,827

,122

15,3

78,0

5311

. Gyp

sum

Pan

el P

rodu

cts

(form

erly

W

allb

oard

)0

00

12,2

82,8

700

00

012

,282

,870

12. W

aste

Sta

biliz

atio

n/So

lidifi

catio

n95

3,23

510

1,89

00

34,0

680

19,7

460

90,7

531,

199,

692

13. A

gric

ultu

re0

00

918,

386

085

,671

00

1,00

4,05

7

14. A

ggre

gate

02,

927

00

00

00

2,92

7

15. O

il/G

as F

ield

Ser

vice

s39

,400

00

00

13,5

580

052

,958

16. C

CR

Pon

d C

losu

re A

ctiv

ities

600,

861

732,

022

389,

539

1,03

5,61

291

,036

378,

224

00

3,22

7,29

5

17. M

isce

llane

ous/

Oth

er21

9,68

168

,669

020

5,21

00

00

28,2

1052

1,77

1

CCP Categorie

sFly Ash

Bottom

 Ash

Boiler S

lag

FGD Gy

psum

FGD Material W

etScrubb

ers

FGD Material

Dry Scrubb

ers

FGD Other

FBC Ash

Totals by

 CCP

 Type/Ap

plica

tion

20,0

81,3

304,

350,

321

1,03

6,91

918

,337

,477

91,0

3649

8,53

20

15,0

45,2

25

Cat

egor

y U

se to

Pro

duct

ion

Rat

e (%

)55

.51%

47.3

0%67

.55%

55.9

3%1.

92%

23.1

4%0.

00%

96.6

2%20

18 C

enos

pher

es S

old

(Pou

nds)

1,19

2,56

8D

ata

in th

is s

urve

y re

pres

ents

127

.524

9915

2 G

Ws

of N

ame

Plat

e ra

ting

of th

e to

tal i

ndus

try

wid

e ap

prox

imat

e 24

8.92

8 G

W c

apac

ity b

ased

on

EIA

's J

uly

2018

Ele

ctric

Pow

er M

onth

ly.

59,4

40,8

39

America

n Co

al Ash Associatio

n      Pho

ne: 720‐870

‐789

720

18 Coa

l Com

bustion Prod

uct (CC

P) Produ

ction & Use Surve

y Re

port

Bene

ficial U

tiliza

tion versus Produ

ction To

tals (Sho

rt Ton

s)CC

P Prod

uctio

n / 

Utilizatio

n To

tals

102,

274,

881

Summary Utilizatio

n to Produ

ction Ra

te

CC

P U

tiliz

atio

n To

tal

59,4

40,8

39

58.1

2%

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720-870-7897 • www.ACAA-USA.org

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