Closed-loop recycling ofsteel products
Nami Kuwana, Toshio Isohara
日鉄総研株式会社* kuwana.n.tdy@nsri.nipponsteel.com

2022年10月31日

1

Steel Production Process
Steel is made by reducing iron ore (iron oxide) with carbon.

Iron oxide

Sintering furnacecarbonCoke ovens

Blast furnace(reduction・melting)

Recycling

Converter(Impurity removal)

Continuous casting

RollingHeat treatment(Strengthening,etc)

Steel product2

Almost all steel products are recycled
In construction materials, steel is mostly recycled.

What happens to the skeleton when the building is demolished

LandfillDown cycling
Concrete

Incineration
Timber

Reuse
Steel3

What are the requirements for autonomous, sustainable recycling?
Steel meets all these requirements.
1. Easy sorting• Automated• Magnetic
2. Lower environmental impact• Lower environmental impact• Scrap metal recycled simply by melting
3. Valuable• High economic value, worldwide recovery system based on market economy.
4. Easy removal of impurities• Refined during recycling• Steel has low alloy additions to begin with and many impurities can be easily removed byoxidation refining.
4

Steel is easy to remove impurities.
Most impurities can be removed by oxygen blowing, as they are more easily oxidised than iron.

平木岳人也: 第23回廃棄物資源循環学会研究発表会（2012） 23_269を改変

ガス相
Gas state

Ce

スラグ相
Slag state

CaMg

NbMn
V

Ni

Impurities which canbe removed/escapeZn

SiCa

B
Cr

溶融
メタル相
Molten metalstate

Ti

Mg

ZnZn

Pb

Impurities which canbe removed

CaMg
AlCe

Co
Sn

Cu
Mo

Steel

B

Ti

SiVFeCo

Pb

Cr

Sn

NbTi

B

Cu Mn
NiMo

aluminum

AlCeVFeSnSiCrPbCo

Nb
CuNiMnMo

Magnesium

CeCo

PbBSiVFeCrSnAlNbCu
Ni

Mn

Impurities
which remain

MoTitanium

Most of the impurities that cannot be removed can be removed by magnetic sorting in advance.
5Type of recycling
Recycling: CLOSED LOOP and OPEN LOOP
Production

Production

NaturalResourcesUse
in society

ClosedLoopNaturalResources

End of
final products
Thermal Recovery
Cascade Recycling

Usein society

Open
Loop
End offinal products

参考：ISO14044

6

Is this Open loop Recycling？
Steel products can be recycled into the same product or into different products.

Recycled to・・・Recycled to・・・

Steel is steel.

:Recycling

Othersteelproducts

Circulation of steel resources
The life cycle of steel material is endless and circulating in a closed manner
worldsteel, World Steel in Figures 2022
worldsteel, Steel Statistical Yearbook 2021
Bureau of International Recycling:
World Steel Recycling in Figures 2017-2021

Naturalresources

鉄リサイクリング・リサーチ, 調査レポートNo.68
21年末の世界鉄鋼蓄積量推計と電炉シェア
United Nations, World Population Prospects 2019

SteelStockClosed loop and Open loops in the ISO 14044 standard.
Can to can recycling of aluminium is closed loop（both in terms of product and recycling）.
製品システムの技術的な記述(1)Technical description of the product system.

Material from the productsystem is recycled in thesame product system.

ClosedLoop

リサイクルのための配分の手順(2)Allocation procedures for recycling.

ClosedMaterial is recycled withoutchanges to inherent properties.

製品システムからの物質が，同じ製品システムにおいてリサイクルされている。

Material from the productsystem is recycled in adifferent product system.
製品システムからの物質が，異なる製品システムにおいてリサイクルされている。

物質は，固有の特性を変えることなくリサイクルされている。

Open

Loop

LoopOpen
Loop

Recycled material undergoeschanges to inherent properties

Figure-Distinction between a technical description of a productsystem and allocation procedures for recyclingリサイクルされた物質は，固有の特性に対する変化を受ける。

Steel product systems (individual steel products)
In terms of product system, steel pipes become different product(H-beams).
Steel product systems (individual steel products)

CokingCoal

BlastFurnace

転炉
BOF

電炉
EAF

Steel Pipes

PipingH-beams

Buildings

Steel Scrap
Recycled to H-beams

Closed loop and Open loops in the ISO 14044 standard.
Pipe to H-beam can still be considered as closed-loop recycling.
製品システムの技術的な記述(1)Technical description of the product system.

Material from the productsystem is recycled in thesame product system.

ClosedLoop

リサイクルのための配分の手順(2)Allocation procedures for recycling.

ClosedMaterial is recycled withoutchanges to inherent properties.

製品システムからの物質が，同じ製品システムにおいてリサイクルされている。

Material from the productsystem is recycled in adifferent product system.
製品システムからの物質が，異なる製品システムにおいてリサイクルされている。

物質は，固有の特性を変えることなくリサイクルされている。

Open

Loop

Loop

Open
Loop

Recycled material undergoeschanges to inherent properties

Figure-Distinction between a technical description of a productsystem and allocation procedures for recycling

リサイクルされた物質は，固有の特性に対する変化を受ける。

ISO20915 Life cycle inventory calculation methodology for steel products
ISO20915 is considered closed loop recycling.

Production(A)Naturalresources

Steel productmanufacturing

Product use

Use of steel scrap(B1)

Japan Iron and Steel Federation ’ Publication of ISO 20915’
https://www.jisf.or.jp/news/topics/181128.html

End of Productlife

Collection of steel scrap(B2)