Imp. scrap 6

(1)

Steel Recycling and Reutilization of Alloying Elements

K. Matsubae‐Yokoyama and T. Nagasaka y g

Tohoku University, Sendai, Japan

(2)

Iron and steel cycle in Japan (2003) source:JISF

Imp. scrap 6

Crude steel Obsolete scrap

Domestic scrap Crude steel

83 Obsolete scrap 34

Accumulation Consumption

127

46 ccu u a o 1263

Exp. commodity 22

Exp. steel products 35

Imp. commodity 4

Imp. steel products

4

(3)

Iron and steelmaking process

Basic oxygen furnace: BOF (Converter)

(steelmaking)

Iron ore Coke

i

Continuous casting: CC (solidification)

Lime 1400

^o

C

1600

^o

C 1600 C

1600

^o

C

Blast furnace: BF (ironmaking)

1600

^o

C

El t i f EAF

Refining

(composition

control) 1000

^o

C

Electric arc furnace: EAF (steelmaking)

)

Rolling

Steel

1000

^o

C

Rolling

(shaping and

Microstructure control)

scrap Human economic

activities

(4)

Coke P, Si

Lime P

Iron ore Mn, P, Si

Steel scrap Al, B, Cu, Cr, Co, Mn, Mo, Nb, Ni, P,

Si, Sn, V, W, Zn Coke

P, Si

Lime P

Si, Sn, V, W, Zn

Blast furnace (ironmaking)

Slag Mn

Ordinary steel products DRI

Mn, P, Si

major flow

Blast furnace (ironmaking)

Slag Mn

Ordinary steel products Ordinary steel products DRI

Mn, P, Si

major flow

Steelmaking, casting

Human i

Slag Mn, P, Si

Special steel products

Sheet and coil Heavy plates major flow

Steelmaking, casting

Human i

Sheet and coil Heavy plates

BOF economic

activities

Rods and bars Pipe and tube

Cast steel products Piles and shapes Dust, sludge

Zn

CIF EAF

BOF economic

activities

Cast steel products Piles and shapes Rods and bars Pipe and tube

Zn

CIF EAF

Non-ferrous metal Al, Cr, Sn, Zn

Ferro-alloy B, Cr, Mn, Mo, Nb, Ni, Si, V, W

Waste Al, Si, W

Surface-coated products Cast steel products

Surface-coated products Cast steel products Surface-coated products Cast steel products

Non-ferrous industry Non-ferrous

industry

Rare metals in the life‐cycle of steel products

(5)

We have three major concerns for the sustainable steel recycling

1) Contamination by or loss of alloying elements, which are mostly important resources in the which are mostly important resources, in the usage of steel scrap as iron resource

l f “ i b d i i ”

2) Significant loss of valuable elements into slag

Development of “scrap soating system based on composition”

during steel refining processes

Development of “slag‐making technology” to recover P, Mn and Cr

3) unefficient intermediate process for dust treatment

treatment

Development of “dust‐making technology” to recover Zn

(6)

Classification of rare metals used in steel

T. Nagasaka: Study on global flow of Metals- An example of material recycling -, Report of ISIJ （2008）

type Element

Well-used ＦｅＣ

Passed through ＳｉＰＳ

One way diffusion ＭｎＭｏＮｂＶ

Partial circulation ＣｒＮｉ

Waste accepted ＷＡｌ* Ｚｎ

MFA is done in Tohoku

＊ including dross

Red：concentrated one in steel industry

(7)

What about “scrap-soating”?

Coke P, Si

Lime P

P, Si

Lime P

Blast furnace (ironmaking)

Slag Mn

Mn, P, Si

major flow

Blast furnace (ironmaking)

Slag Mn

Mn, P, Si

major flow

Steelmaking, casting

Human i

Steelmaking, casting

Human i

BOF economic

activities

Zn

CIF EAF

BOF economic

activities

Zn

CIF EAF

Non-ferrous industry Non-ferrous

industry

Rare metals in the life‐cycle of steel products

(8)

Demand of rare metals in the world

(a)Ni, Consumption(World) : 1 253 ×10

³

Ni t (2004)

(b)Cr, Consumption(World) : 4 695 ×10

³

Cr t (2003)

Large amount of rare metals are consumed in Japan. On the other hand, it is expected to increase consumptions of rare metals in other Asian countries(China, Korea…) with industrial development.

1,253 ×10

³

Ni-t (2004)

others: 46% China: 12%

Japan: 15%

th 44% China: 13%

South Africa: 14%

4,695 ×10

³

Cr-t (2003)

others: 46%

America: 11%

others: 44%

Kazakhstan : 12%

Korea: 8%

Germany: 8% Germany: 6% Japan: 11%

(c)Mo Consumption(World) : (d)Mn Consumption(World) :

others: 18%

(c)Mo, Consumption(World) : 175 ×10

³

Mo-t (2004)

(d)Mn, Consumption(World) : 19,630 ×10

³

t (2001)

others: 28%

China: 35%

Japan: 6%

China: 13%

America: 21%

EU: 33%

Japan: 15%

8

Ukraine: 14%

India: 8%

South Africa: 9%

(9)

12 14

Stainless steel austenitic

Heat‐resisting steel bars austenitic

High manganese steel castings

Mn Mn

10

Mn

6 8 濃度（mass%）

concentration (mass%)

2 4

Carbon tool steelｓ

general structure steel

鋼鋼材イト系ト系系系系系系系

0 2

生産量（ｔ）

1 10010 000

average percent in steel products steel for building structure

機械構造用鋼ンレス　オーステナイステナイト・フェライトテンレス　フェライトレス　マルテンサイトステンレス析出硬化棒　オーステナイト熱鋼棒　フェライト系棒　マルテンサイト系　オーステナイト系鋼板　フェライト系耐食耐熱超合金棒耐食耐熱超合金板炭素工具鋼鋼材速度工具鋼鋼材耐衝撃工具鋼用ばね鋼鋼材快削鋼鋼材軸受鋼鋼材ガン鋼鋳鋼品用圧延鋼材張力鋼鋼材加工用鋼材器用鋼材築用鋼材道用鋼材管用鋼管用鋼管用鋼管用鋼管線材

1

S1

10

100 生産量（ｔ）

1,000 10,000 100,000 1,000,000 10,000,000 amount in products (t)

ステンステンレスオーススステンレス耐熱鋼耐熱耐熱鋼棒耐熱鋼板耐熱鋼耐耐高合金工具鋼鋼材耐高マンガ一般構造鉄塔用高張一般加圧力容土木建鉄道配管熱伝達構造用特殊用途用ピアノ 100

1,000 10,000

100,00 1 00 , ,

100,000,000

Stainless steel

Heat‐resisting steel bars

鋼種

1,00 10

steel grade general processing steel

(10)

12

Stainless steel austenitic

Mo

Corrosion‐resisting and heat‐

ll b

Mo

8

10 Stainless steel austenitic Heat‐resisting

steel bars austenitic High speed tool steels resisting superalloy bars,

plates and sheets special purpose

steel pipes

Mo

6 濃度（mass%）

concentration (mass%)

Heat‐resisting steel plates and sheets

austenitic steel pipes

2 4

general processing steel

鋼鋼材イト系ト系ト系ト系化系ト系系系系

0 2

生産量（ｔ）

1 10 amount in products (t) 100

average percent in steel products

general processing steel

機械構造用鋼ンレス　オーステナイステナイト・フェライステンレス　フェライトレス　マルテンサイトステンレス析出硬化鋼棒　オーステナイト熱鋼棒　フェライト系棒　マルテンサイト系板　オーステナイト系鋼板　フェライト系耐食耐熱超合金棒耐食耐熱超合金板炭素工具鋼鋼材速度工具鋼鋼材耐衝撃工具鋼用ばね鋼鋼材快削鋼鋼材軸受鋼鋼材ガン鋼鋳鋼品造用圧延鋼材張力鋼鋼材加工用鋼材容器用鋼材建築用鋼材道用鋼材管用鋼管達用鋼管用鋼管用鋼管ノ線材

1S1 10

100 1,000

10,000 100,000 1,000,000 10,000,000 amount in products (t)

ステステンレスオースステンス耐熱鋼耐耐熱鋼棒耐熱鋼板耐熱耐高合金工具鋼鋼材高マンガ一般構造鉄塔用高一般圧力容土木建鉄配管熱伝達構造特殊用途用ピアノ 100

1,000 10,000

100,00 1,00 10,000,000

100,000,000

Stainless steel

Heat‐resisting steel bars

鋼種

1,00 10

steel grade

High manganese steel casting

steel for building structure

(11)

15 (A) to gas (B) to metal

5 10

Cu A

Ni

a g ) ⁰

5 Cu Ag

Pb Zn Mn

Fe Sn

Cr Ni

Co Si V

Mo Nb

W (B) to metal

g (L M/Sl a -5

Mg V Mn

Ti B Si

Nb

Ta Sr

(C) to slag

lo g

-15

-10 Ca

Al

C Zr U

Distribution model for Fe converter

-20 La

xi(Me) in Fe = 0.01 (mol fraction)

Ce

p_O2= 1.9 x 10^-10(atm)

p_Fe= 8.5 x 10^-5(atm) T = 1873 K

log(L _M/G )

-25

-15 -10 -5 0 5 10

Distribution chart of elements among gas, slag, and metal phases for the metal recovery under the simulated atmosphere of converter of steel making.

log(L _M/G )

(12)

Iron ore

Ferro

alloy Electric Arc Furnace (EAF) Stainless t l

scrap

y ( )

steel

scrap

Human economic activities

Blast Furnace (BF)‐

Converter (BOF)

(13)

Present situation of steel recycling

(14)

What about “slag-making technology”?

Coke P, Si

Lime P

P, Si

Lime P

Blast furnace (ironmaking)

Slag Mn

Mn, P, Si

major flow

Blast furnace (ironmaking)

Slag Mn

Mn, P, Si

major flow

Steelmaking, casting

Human i

Steelmaking, casting

Human i

BOF economic

activities

Zn

CIF EAF

BOF economic

activities

Zn

CIF EAF

Non-ferrous industry Non-ferrous

industry

Rare metals in the life‐cycle of steel products

(15)

to Metal phase

Elements that have distributed

Au Pt

Rh Pd

Ag Ag

Hg Zn

to Slag phase

among the metal phase as a solid or liquid metal

Ag

Sn Bi

Al Ga

Ge

In Cu Se Re

Te Ni

B

Sb

Fe Pb

Sr W

V Sn

Al Cr

Mn Mg

Cu

Co Ca Ni

Fe

Hg Zn

to Gas phase

Elements that have distributed among the slag phase as oxide

Cu

(Converter)

Hg

Al Cr In

Mn

Mg Zn

Fe

Sr

(BOF,EAF)

Ta Nb

V Al

Zr

B U

Si Ce W

Mo Ti La

Hg d

Cd

Elements that have evaporated and distributed among the gas phase .

Al Z &Pb

Pt Au

Cr Pd W

Fe b

In

Bi Pb

Li Sr Yb HgCd Zn

Mg

Recyclable element Alloying element Al

(Remelting)

Zn&Pb

(ISP)

Pd

Ag Sn

Bi Al

Cr Ga

In Mn

Mg

Cu Ni

Pb

Pb Ti

Ho Si

Dy

Cr Ge Cu

SnMn As

GaAg Sb YbSr

AlCa Be

Hg Pb Zn

(Blast furnace)

Al Cr Mg

Au

MoNb La Zr Y CeU V CoB

Ni Pd

Fe Ti Gd Cr

Pt Pd Ag Hg Sn

Cr Ga

In Mn

Cu Ni

Fe W

Pb Zn

Pt Ir TaW Mo

Element distribution metal wheel

Ag Au Bi

(16)

K. Nakajima, K. Yokoyama and T. Nagasaka: Substance Flow Analysis of Manganese Associated with Iron and Steel Flow in Japan, ISIJ International, 48 (2008), 554-558 Y.-S. Jeong, H. Kubo, K. Matsubae-Yokoyama, J.-J. Pak and T. Nagasaka: Substance Flow Analysis of Phosphorus and Manganese Correlated with Korean Steel Industry, Resources, Conservation and Recycling, 53 (2009), 479-489

Ferrous resource

Iron making

(111.1 & 266.2)

Ferrous resource Unit: kt -Mn/yearUnit: kt -Mn/year (South Korea & Japan)

Iron making

(111.1 & 266.2)

Blast furnace Dust

BF slag (15.9 & 55.4) (0.1 & 1.9)

Blast furnace Dust

BF slag (15.9 & 55.4) (0.1 & 1.9)

Pig iron

Steel making

_Scrap

(95.1 & 208.9) (62.9 & 241.7)

Pig iron

Steel making

_Scrap

(95.1 & 208.9) (62.9 & 241.7)

BOF/EAF

g

Iron -Mn ore /Mn ore Scrap

(158.0 & 450.6)

(5.0 & 92.8) BOF/EAF

g

Iron -Mn ore /Mn ore Scrap

(158.0 & 450.6)

(5.0 & 92.8)

Ladle Ferro -Mn

Si M Steel making

Slag

(243.0 & 577.6) (146.0 & 530.7)

Ladle Ferro -Mn

Si M Steel making

Slag

(243.0 & 577.6) (146.0 & 530.7)

Crude steel

Si -Mn (260.0 & 590.3)

Crude steel

Si -Mn (260.0 & 590.3)

Material flow of manganese in Japanese and South Korean steel industries (2005)

(17)

Why Phosphorus・・・?

An essential element for animals and plants nutrition.

Supply of P often becomes critical for growth of plants

Nutrition barrel

Water level in the barrel, which is determined by the shortest plate, means growth degree of plant.

P , N, K

(18)

About Phosphorus・・・

• Domestic production：none （import only!）

• Main use：raw materials of fertilizer

1600

24%

4%

3%2% 11% United State

Morocco China

24%

1000 1200 1400

Other country Jordan

China

kt/y ea r

17%

5%

5% Russia

Jordan Tunisia Brazil

Total:

44,100 kt

17%

5%

400

%

600 800 1000

South Africa Morocco

U.S.A

h orus ro ck

h h k d

16%

13% Israel

South Africa other countries

16%

13%

0 200 400

1993 1994 1996 1998 2000 2002

Phosp h

Phosphorus rock production rate in the world. (2002)

Ministry of finance Japan “Trade Statistics”

Quantity about phosphorus ore import.

year

Phosphorus ore is a kind of national strategic resources

(19)

Trend in EU

Situation seems to be same in EU! (1000 t, 1995) (reported by European commission in 2000)

USA FSU* Morocco Algeria Tunisia Jordan Israel Togo S. Africa Other

Austria 65.2 4.8 12.8 20.5 10.3 48.0

Belgium 190.8 158.4 514.2 20.5 17.6 629.1

Denmark 67.3 6.4 11.8 5.5 15.5 33.0

Finland 91.3

France 16.9 212.7 110.9 196.5 646.3 103.3 199.9

Germany 78.7 22.2 66.4 67.5 14.6

Greece 19.3 91.4 5.3 155.4 75.9 131.1

Ireland 0.4 10.0

Italy 202.7 3.0 13.8 44.0

Netherl. 269.0 483.6 276.2 447.6 290.1 20.9 88.0

Portugal 6.0 22.9 128.0

Spain 1624.4 13.2 18.2 54.3 49.0

Sweden 70.5 5.0

UK 11.9 8.2 10.4

Total EU 538.9 851.6 3082.2 263.0 273.3 696.5 975.1 233.5 665.4 721.0

(20)

Trend in other country

Brazil was phosphorus exporting country

But now they are importing phosphorus due to bio‐fuel production

p

(21)

Trend of price of phosphate rock

500

600

e) 500

400

($/t ‐or

200

300

t price 200

100

Impor t

0

0 2 4 6 8 10 12

1/06 1/07 1/08

0

(22)

Phosphorus problems

Efficiency of phosphorus as fertilizer strongly depends on the composition of soil and kind of crop

Phosphorus is unsubstitutable element for plants and crops Phosphorus is unsubstitutable element for plants and crops Phosphorus deposits are in very limited area p p y

Phosphate rock mining sometimes causes water pollution

Supply of phosphorus strongly links to the production of food and bio fuel

bio‐fuel

(23)

What’s de-P process?

Phosphorus is a kind of natural enemy for

BOF or TPC

Phosphorus is a kind of natural enemy for steel product

One of the main objectives of steel-making One of the main objectives of steel making process is “dephosphorization”

before 0.1～0.15％P

Slag

Molten P

after 0.02～0.01％P Molten

iron

P Typical de-P flux

CaO-FeO-SiO

₂

-P

₂

O

₅

system

Ladle

(24)

Phosphorus and the Titanic

K. Felkins, H.P. Leighly, Jr., and A. Jankovic:

The Royal Mail Ship Titanic: Did a Metallurgical Failure Cause a Night to Remember?

Journal of Metals, 50 (1) (1998), pp. 12‐18.

Figure 1. The Titanic under construction at the Harland and Wolff shipyard in

Ireland. (Photo courtesy of the Titanic Historical Society.)

(25)

Phosphorus and the Titanic

Table The Composition of Steels from the Titanic, and ASTM A36 Steel

C Mn P S Si Cu O N MnS: Ratio

Ti i H ll Pl 0 21 0 4 0 04 0 069 0 01 0 024 0 013 0 003 6 8 1

Titanic Hull Plate 0.21 0.47 0.045 0.069 0.017 0.024 0.013 0.0035 6.8:1

ASTM A36

0.20 0.55 0.012 0.037 0.007 0.01 0.079 0.0032 14.9:1

The presence of relatively high amounts of phosphorous, oxygen, and sulfur has a tendency to embrittle the steel at low temperatures.

There is a high probability that the steel used in the Titanic was made in an acid‐lined open‐

hearth furnace, which accounts for the fairly high phosphorus and high sulfur content.

(26)

Phosphorus and the Titanic

Low

ss rit tlena B r

High

Effect of P on brittleness factor

(27)

That’s why phosphorus should be removed from steel

Topedo‐car （→）

transporter of 300 ton of hot metal transporter of 300 ton of hot metal (molten pig iron) produced by BF to BOF shop

Slag generated on the surface of hot metal （↓）

Generally CaO‐FeO‐SiO

₂₂

‐P

₂_{2 5}

O

₅

P content :1～5

CaO and Fe

₂

O

₃

(or O

₂

) are injected into hot metal

to oxidize phosphorus in iron and formed P

₂

O

₅

is

stabilized in slag as calcium‐phosphate g p p

(28)

Tragedy of phosphorus in slag

“We are producing high quality steels, not slag”, steelmaker said.

(29)

Tragedy of phosphorus in slag

Slag is well recycled as road construction materials.

“After all slag is slag” steelmaker said

“After all, slag is slag”, steelmaker said.

(30)

Recent topics on phosphorus

(31)

Recent topics on phosphorus

Env. Sci. Tech., (2007), pp.2078.

(32)

Trend of steelmaking slag generation in Japan

170

160 e el to

n 150

/c ru d e st e

140 kg

120 130

89 90 95 00 05 07

Year

(120 million ton of crude steel) x 160 kg/crude steel t = 19 million ton of slag

(33)

In short…

• Phosphorus is very important and strategic

resource for us while it is a kind of a natural enemy for steelmaker.

for steelmaker.

• We don’t know exactly how much phosphorus goes

• We don t know exactly how much phosphorus goes through our society.

• On the other hand…., the amount of phosphorus

which goes through steelmaking industry should be

very large.

(34)

Domestic material flow of phosphorus

River/

Trade/ Fishery Unit：1000t （P mass）

Fertilizer

173.4

Food & Feed Livestock

F /R River/

Coast area

Fertilizer Food & Feed

Fertilizer

Chemical industry

141.3

395.2

111.6

miscellaneous drainage

Phosphorus

ore Livestock

Human Farm/R

anch

Human

Waste

110.6 129.3

224.9 54.5

Sludge

57.5

Chemical industry

miscellaneous drainage Soil

accumulation

155.9 356.1 145.2 42.8 ^Fertilizer

Other industry

Products/ by- products

Oth i l

River/

Coast area Sludge

Steelmaking industry

157 2

63.9 88.2 10.5

Steelmaking industry Other mineral

resources

D ti

Nature

Farm/Ranch

Steel

Human Sludge

Fertilizer Waste

157.2

103.6

96.4

^54.5

industry Domestic

products Slag Waste

Food & Feed Livestovk Chemical

industry

Yokoyama, Kubo, Okada, Takeuchi, Nagasaka:ISIJ Intern., 92(11) (2006), .pp.683

(35)

O h i

Material flow of P among countries

Y.-S. Jeong, H. Kubo, K. Matsubae-Yokoyama, J.-J. Pak and T.

Nagasaka: Substance Flow Analysis of Phosphorus and Manganese Correlated with Korean Steel Industry, Resources, Conservation and Recycling, 53 (2009), 479-489

Other countries

Fertilizer Phosphate

rock

Soil Sewage

Sludge

15994

Unit: 1000t (P mass)

rock Sludge

Japan

87 73 141

Fertilizer Phosphate

rock

Soil Sewage

Sludge

87 23 110

Slag 474 96

Korea

42

69 Fertilizer Phosphate

rock

Soil Sewage

Sludge

136

154 Slag 142 38

China

Soil Fertilizer

Phosphate rock

Soil Sewage

Sludge

4885 4195

(36)

Micro-structure of slag after cooling

(37)

Rare metals （Cr+Mn+Zn) balance in EAF process

Average of three steel works which produce about 1000 k‐ton/year

Dust: 18 Slag 115.5

Zinc concentrating process

Cr+Mn: 0.15 Zn: 4 05

g

Cr+Mn: 6.3

Scrap 1050

Zn: 4.05

Steel products: 1000

EAF

Accumulation of rare metals in steel products

Scrap 1050 Cr+Mn: 9.1

Steel products: 1000 Cr+Mn: 13.5

EAF

Zn: 4.2

Slag loss of rare metals

Ferro‐alloy Cr+Mn: 10.85

Unit: k‐ton

(38)

Micro‐structure of slag for special bar steel

I C Si Al

100 μm

Image Ca Si Al

Fe Mn Cr Mg

(39)

Possibility of magnetic separation

Matrix phase FeO CaO SiO (MnO) Matrix phase FeO-CaO-SiO

₂

(MnO)

Calcium phosphate

(I f )

(Iron free)

MnO-FeO

(40)

Trial of magnetic separation

< Wet High Intensity Separators > Mn rich phase and

- Eriez Series L Model 4 Laboratory -

P rich phase Matrix phase

Mag.

Un mag.

Stainless filter

(41)

results

FeO CaO SiO

₂

P

₂

O

₅

MnO

22 51 42 36 11 05 2 24 3 49

22.51 42.36 11.05 2.24 3.49

P

8

MnO

MnO, P₂O₅in recovered slag [wt%]

4

6

P₂O₅

3

4

M

MnO wt%

2

Mn

2 1

0

0.03Ｔ 0.05Ｔ 0.10Ｔ 0.20Ｔ 0.30Ｔ非磁着物

0

unmagnetized

(42)

What about “dust-making technology”?

Coke P, Si

Lime P

P, Si

Lime P

Blast furnace (ironmaking)

Slag Mn

Mn, P, Si

major flow

Blast furnace (ironmaking)

Slag Mn

Mn, P, Si

major flow

Steelmaking, casting

Human i

Steelmaking, casting

Human i

BOF economic

activities

Zn

CIF EAF

BOF economic

activities

Zn

CIF EAF

Non-ferrous industry Non-ferrous

industry

Rare metals in the life‐cycle of steel products

(43)

Rare metals （Cr+Mn+Zn) balance in EAF process

Average of three steel works which produce about 1000 k‐ton/year

Dust: 18 Slag 115.5

Cr+Mn: 0.15 Zn: 4 05

g

Cr+Mn: 6.3

Scrap 1050

Zn: 4.05

Steel products: 1000

EAF

Scrap 1050 Cr+Mn: 9.1

Steel products: 1000 Cr+Mn: 13.5

EAF

Zn: 4.2

Ferro‐alloy Cr+Mn: 10.85

Unit: k‐ton

(44)

EAF process

(45)

Carbon electrode

Pressed scrap

Heavy scrap

(46)

dust

(47)

dust

l b d

EAF Dust: Zn 20‐30%, Fe 25‐35%, Cl+F 5‐15%, Pb, Cd, etc.

(48)

ferro‐

ferro alloys

slag

(49)

slag slag

metal

Tapping ladle

pp g

(50)

Zinc ore,

Zinc flow in Japan

K. Nakajima, K. Matsubae, S. itoh, S. Nakamura and T. Nagasaka:

S 2008

(c) 134.6

Landfill Zinc scrap

, Other zinc

resource

ISIJ Intern, 2008

Import: 45.9

Steel

30.4 (10

³

t‐Zn)

Zinc

m and

304

Export: 53.7

(a) 638.6

mic

Zinc Refinery

Steel scrap

e st ic de m

Import: 2.7

an ec ono activity ^86.5 (10

³

t Zn)

Zinc Recycler

EAF

Dom e

Export: 11.7

123 (b) 36.7

Oth

Hum a a (10

³

t‐Zn)

18.8

3

Recycler

EAF dust

109

Copper and copper

base alloys, Die cast, Zinc plates

Others

56.2 (10

³

t‐Zn)

(10

³

t‐Zn) 1.9

(10

³

t‐Zn) (10 t Zn)

49.5 (10

³

t‐Zn) Cement

Intermediate‐

treatment

Zinc oxide

(51)

N f Crude ZnO Non-ferrous

industry

Crude ZnO

Domestic supply Except for import & export

53.6 Surface coated steel 30.4

Alloy, di-cast

12.1 Others

11.1 Human economic activity Intermediate

treatment (Waelz process)

St l i d t

Steel scrap (Waelz process)

6.0 Steel industry

No recycling

Scrap 1.8

Steelmaking dust

10.2

(52)

Conclusion

EAF acts extremely important role for sustainable steel EAF acts extremely important role for sustainable steel cycle and rare metals consumption.

Understanding and control of substance flow through the life‐cycle of steel products are also very important.

the life cycle of steel products are also very important.

Scrap sorting based on the composition and slag‐making Scrap sorting based on the composition and slag making technology will result in great saving of rare metal

Imp. scrap 6

Steel Recycling and Reutilization of Alloying Elements

K. Matsubae‐Yokoyama and T. Nagasaka y g

Tohoku University, Sendai, Japan

Iron and steel cycle in Japan (2003) source:JISF

Imp. scrap 6

Crude steel Obsolete scrap

Domestic scrap Crude steel

83

Obsolete scrap 34

Accumulation Consumption

127

46

ccu u a o 1263

Exp. commodity 22

Exp. steel products 35

Imp. commodity 4

Imp. steel products

4

Iron and steelmaking process

Basic oxygen furnace: BOF (Converter)

(steelmaking)

Iron ore Coke

i

Continuous casting: CC (solidification)

Lime 1400

C

1600

C 1600 C

1600

C

Blast furnace: BF (ironmaking)

1600

C

El t i f EAF

Refining

(composition

control) 1000

C

Electric arc furnace: EAF (steelmaking)

)

Rolling

Steel

1000

C

Rolling

(shaping and

Microstructure control)

scrap Human economic

activities

Blast furnace (ironmaking)

Blast furnace (ironmaking)

Steelmaking, casting

Human i

Steelmaking, casting

Human i

BOF economic

activities

CIF EAF

BOF economic

activities

CIF EAF

Non-ferrous industry Non-ferrous

industry

Rare metals in the life‐cycle of steel products

We have three major concerns for the sustainable steel recycling

1) Contamination by or loss of alloying elements, which are mostly important resources in the which are mostly important resources, in the usage of steel scrap as iron resource

l f “ i b d i i ”

2) Significant loss of valuable elements into slag

Development of “scrap soating system based on composition”

during steel refining processes

Development of “slag‐making technology” to recover P, Mn and Cr

3) unefficient intermediate process for dust treatment

treatment

Development of “dust‐making technology” to recover Zn

Classification of rare metals used in steel

type Element

Well-used Ｆｅ Ｃ

Passed through Ｓｉ Ｐ Ｓ

One way diffusion Ｍｎ Ｍｏ Ｎｂ Ｖ

Well-used ＦｅＣ

Passed through ＳｉＰＳ

One way diffusion ＭｎＭｏＮｂＶ

Partial circulation ＣｒＮｉ

Partial circulation ＣｒＮｉ

Waste accepted ＷＡｌ* Ｚｎ

a g ) ⁰