Re-use of EAF Slag into Ceramic Floor Tile

By

Assoc. Prof. Dr. Nurulakmal Mohd Sharif

School of Materials & Mineral Resources Engineering, USM

CONTENTS

1.0 Introduction

2.0 Experimental Work

3.0 Result & Discussion

4.0 Conclusion

Problem Huge annual EAF slag waste generated in steel industries created disposal problem.

Initiative USM and Southern Steel Berhad collaboratively find a way to re-use the EAF slag waste.

Solution Re-use of EAF slag waste as partial replacement of raw materials in tile making. GREEN HDTile

Statistics of Steel Production (EAF Route)

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100

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400

500

2009 2010 2011 2012 2013 2014 2015

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Oceania

Middle East

SouthAmericaNorthAmericaEurope

C.I.S

Asia

Africa

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5

6

7

2009 2010 2011 2012 2013 2014 2015

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Year

Source: World Steel Association, 2016

Statistics of EAF Slag Waste Generated

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2009 2010 2011 2012 2013 2014 2015

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2009 2010 2011 2012 2013 2014 2015

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WORLDWIDE (2009 – 2015) MALAYSIA (2009 – 2015)

WORLDWIDE (2009 – 2015) MALAYSIA (2009 – 2015)

RECYCLING OF EAF SLAG WASTE

EAF SLAG

Ceramic Floor Tile

Fertilizer / Soil conditioner

Aggregate for structural concrete & road pavement

Portland cementing material

Adsorbent for waste water treatment

Preliminary : XRF Chemical Composition of Slag

Preliminary study : XRF to analyse chemical composition,

leaching test & XRD : assess variation in composition

between different batches.

Oxide

Chemical Composition (wt.%)

Batch A (Aug 2013)

Batch B (Dec 2013)

Batch C (Apr 2014)

Batch D (Aug 2014)

Batch E (Dec 2014)

Batch F (Apr 2015)

Range MeanStd. Dev.

Al2O3 9.14 8.77 8.97 8.52 8.76 8.65 8.52-9.14 8.80 0.22

CaO 26.41 26.80 27.49 27.18 26.71 29.75 26.41-29.75 27.39 1.22

Cr2O3 1.21 1.27 1.11 1.01 1.26 1.04 1.01-1.27 1.15 0.11

MgO 3.60 2.03 3.13 3.64 2.06 3.13 2.03-3.64 2.93 0.72

MnO 4.05 4.24 3.99 4.09 4.25 3.83 3.83-4.20 4.08 0.16

SiO2 20.37 19.91 20.71 20.17 19.99 20.21 19.91-20.71 20.23 0.29

Total Fe

33.24 35.11 32.52 33.75 35.18 31.36 31.36-35.18 33.53 1.49

Ceramic Floor Tile

EAF

Slag

Clay

Typical Composition

Oxide wt. %

Total Fe 30 – 35

CaO 25 – 30

SiO2 18 – 21

Al2O3 8 – 9

MgO 2 – 4

Filler

(Silica)

Flux

(Feldspar)

XRD profile for EAF Slag :

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

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100

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800

LLLG

G LGG

G

G

G

LLGG

G

G

G

GG

GG

L

G

G

G

G

G

G

GG

GG L

L

LLL

LLL

L

L

L

L

LLLL

LL

L

LL

LL

L

L

LLL

L

LLL

L

L

L

L

L

LL

L

L

L

LLL

L

W

W

W

W

W

W

In

tensi

ty (

a.u.)

2()

G

WL

GL

GL

G: Gehlenite, Al2O3.2CaO.SiO2

(ICSD No: 98-001-7144)

L: Larnite, 2CaO.SiO2

(ICSD No: 98-000-5670)

W: Wustite, FeO(ICSD No: 98-008-8080)

Drying of green body (110°C/24 hours)

Firing (1125°C, 1137°C &

1150°C)

Crushing of EAF slag into micron size powder

Mixing of raw powders & Ball milling (5 hours)

Drying of slurry (120°C/24 hours)

Milling of dried slurry

Moistening & Granulation

(5 – 6 wt.% of water)

Powder mixture

Compaction (40 MPa)

Methodology

Characterization of fired tile : density, XRD, MOR, water

absorption

Table 1: Composition of EAF slag added ceramic tile

Composition

Weight percentage (wt. %)

EAF slag Ball clay K-feldspar Silica

0F0S 50 50 0 0

0F10S 50 40 0 10

10F0S 50 40 10 0

10F10S 50 30 10 10

5F5S 50 40 5 5

Run

order

Factors Responses

wt. % of K-

Feldsparwt. % of Silica

Firing

TemperatureWater Absorption MOR

1 5 5 1137 0.29 97.85

2 10 10 1125 0.18 82.51

3 5 5 1137 0.34 97.48

4 0 10 1150 0.04 88.66

5 10 10 1150 0.03 94.68

6 0 0 1125 8.92 50.63

7 0 0 1150 2.91 63.07

8 10 0 1150 5.55 59.50

9 0 10 1125 0.10 96.79

10 10 0 1125 9.45 44.45

11 5 5 1137 0.20 98.17

Mineral Phase Presence

Percentage(%)

H – Hematite (Fe2O3)M – Magnetite (Fe3O4)A – Anorthite(Al2O3.CaO.SiO2)W – Wollastonite(CaO.SiO2)

TOTAL A & W

2.08.3

46.8

42.9

89.7

XRD PHASE ANALYSIS RESULT

XRD Peak: Composition I (50 wt.% EAF slag – 50 wt.% ball clay), fired at 1180 ˚C;

Lowest water absorption & highest MOR

10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90

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M

M

M

M

M

W

W

W

W

W

WW

W

WWWA

W

W

W

W

W

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WW

W

A A

AA

A

AA

A

A

A

A

A

A

AA

A

A

In

ten

sit

y (

a.u

.)

2()

A

AW

Hump (presence of glassy phase)

Rietveld Refinement:

Agreement indices:

Weighted R Profile (Rwp):

10.38

Goodness of Fit (GOF): 3.31

Both Rwp and GOF were lower

than 20 and 5, respectively

Phase identification &

quantification performed

were mostly reliable

Weight Percentage (wt.%)

Anorthite Wollastonite Magnetite

70.10 18.10 11.80

A: AnorthiteW: WollastoniteM: Magnetite

Correlation between total wt.% of anorthite and wollastonite, and

MOR of ceramic tile

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A B C D E F

MO

R (

MP

a)

We

igh

t P

erc

en

tage

(w

t.%

)

Composition

Total Anorthite and Wollastonite MOR

DSC : Sintering Mechanism

Stage 1: 100 ˚C – 250 ˚C

Free water on particle surfaces of tile powder

mixture was removed

Stage 2: 450 ˚C – 600 ˚C

Kaolinite in clay decomposed into metakaolin

(dihydroxylation of clay)

6Al2Si2O5(OH)4 [kaolinite] → Al2O3.2SiO2

[metakaolin] + 2H2O [water]

Stage 3: 1100 ˚C and above

FeO (in slag) reacted with silicates & alumina-

silicates (in mixture) form compound the

compound melted into glassy phase (proven by

hump peak in XRD profile)

Concurrently, metakaolin (from Stage 2) transformed

into ϒ – Al2O3 & highly reactive SiO2. Subsequently,

gehlenite (from slag) & larnite (from slag) reacted

with them, forming anorthite & wollastonite

crystalline phases in the tile.

Stage 1

Stage 1

Stage 1

Stage 1

Stage 2

Stage 2

Stage 2

Stage 2

Stage 3

Stage 3

Stage 3

Stage 3

Phase transformation of clay:

i. At 420 - 660ᵒC:

Si2Al2O5 (OH)4 (kaolinite) → Al2O3.2SiO2 (metakaolinite) + 2H2O

ii. At 900ᵒC:

Al2O3.2SiO2 (metakaolinite) → SiO2 (silica) + Al2O3 (alumina)

Formation of anorthite & wollastonite:

i. 2[Al2O3.2CaO.SiO2] (gehlenite, from EAF slag) + Al2O3 (from

clay) + SiO2 (from silica & clay) → 3[Al2O3.CaO.2SiO2]

(anorthite) + CaO.SiO2 (wollastonite)

ii. 2CaO.SiO2 (larnite, from EAF slag) + SiO2 (from silica & clay)

→ 2[CaO.SiO2] (wollastonite)

MOR (modulus of rupture)

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Composition F(Prelimary

Study)

Composition F(EAFS: 6 µm)

Composition F(EAFS: 3 µm)

Composition I(Sintering

Study)

Alpha Guocera Venus White Horse

MO

R (

MP

a)

XX YY ZZ XYZ

Conclusion

Amount of EAF slag influence properties of tile, as also

the body composition.

Suitable sintering temperature is important.

Strong correlation between body composition and

sintering temperature with the amount of resultant

phases (anorthite + wollastonite) and final properties of

tile (MOR, water absorption).

Potential re-use of EAF slag into ceramic floor tile.

Source: D. Gabaldón-Estevan, E. Criado & E. Monfort, 2014. The green factor in European manufacturing: A

case study of the Spanish ceramic tile industry, Journal of Cleaner Production, 70, 242-250

GREEN CERAMIC TILE from EAF SLAG

Industrial’s waste as raw

material

Non-hazardous

Recyclable

Cost Effective

Thank Yousrnurul@usm.my