Innovation for Cool Earth Forum (ICEF)
9th Annual Meeting

REE-rich mud:An innovative seafloor resource
for Sustainable Development Goals
Yasuhiro Kato

Vice Dean / Professor
School of Engineering, The University of Tokyo

Rare-earth elements (REE) as a key material for SDGs
Electrification of vehicles
Reuters(2019.7.11)
BBC NEWS(2017.9.10)

Bloomberg(2020.9.24)

Reuters(2020.12.3)

NIKKEI Asia
(2021.7.15)

Rapid growth of wind power generation
Reuters(2020.11.29)

Reuters(2021.11.14)

The Japan Times(2020.12.16)

Reuters(2022.3.21)

Principal uses of REE

EV/HVLED

Fuel cellwind power
generation

MRI

optical glass

Smartphone

Phosphorescentpigment

laminatedceramic capacitor

Optical fiber

Catalyst forpharmaceutical

Coating materialfor semiconductor

REE are strategic materials crucial for Green-energy technologies
 Novel electronic equipment
 Aerospace instruments etc…

Problems on the current REE resources
Serious environmental problems
with onshore REE deposits
LREE deposits

ion-absorption-type
deposits in southern China

Bayan Obo (China)(hydrothermal Fe-oxide)

Protest against REE
refinery in Malaysia

High Th and U concentrations cause
serious problems of radioactive waste

HREE deposit Mt. Pass mine (US) is partly funded by a Chinesecompany and its ores are smelted in China
 Ores from Myanmar are smelted in China

Almost all deposits are of LREE
Industrially critical HREE are exclusively producedby ion-absorption-type deposits in southern China

Longnan (China)(ion-absorption-type)River pollution byin-situ leaching

Outflowing of the leaching acids causesa severe environmental pollution

The most important
problem to be solved

“The rare-earth crisis”
Bloomberg(2019.6.5)

REUTERS(2019.5.29)

AFP(2019.5.30)

Bloomberg(2019.6.4)

The Mainichi(2019.6.9)
Reuters(2021.2.19)

REUTERS(2019.5.30)

REUTERS(2019.6.6)

Bloomberg(2022.9.10)

The U.S. is seeking a way to strengthen its supply chain
by getting rare-earths from sources other than China,
but is not successful until now…

REUTERS(2022.7.18)

Discovery of a new REE resource
1. High REE (HREE) contents

3. Easy exploration

4. Easy leaching by
dilute acids

REE-rich mud

50% of REE in the mud are HREE, which
is highly profitable as a mineral resource

REE resource can be
simply estimated by taking
piston cores from the four
corners of the area

>97% of REE are easily
extracted by dilute acids
under a room temperature
within 1−3 hours

2. Enormous resource potential

5．Low contents of radioactive elements (Th & U) On-land deposits
show very highcontents ofradioactiveelements
 REE-rich mud hasvery low Th & U~1,000 times larger than the world’s
current land reserves of REE

Kato et al. (2011 Nature Geoscience)

REE-rich mud is a clean and harmless resource

Discovery of extremely REE-rich mud in the Minamitorishima EEZ
Biogenic Calcium
Phosphate (BCP; fishbones and teeth)

KR13-02
PC05(JAMSTEC)

extremely
REE-rich
mud layer
Extremely REE-rich
mud area
Nakamura et al. (2016 Geochemical Journal)
REE-rich mud
Extremely
REE-rich mudEEZ

500 µm(Iijima et al., 2016
Geochemical Journal)(Ohta et al., 2016 Geochemical Journal)>7,000 ppm of total REE
in bulk sediment(JAMSTEC)(~20 times higher than on-landdeposits in southern China)
Extremely REE-rich mud is also enriched in scandium(JAMSTEC)

KR13-02
PC05

High-performance alloy

Solid-oxide fuel cell(JAMSTEC)

Resource potential of REE in the Minamitorishima EEZ(Takaya et al., 2018 Scientific Reports)
Nakamura et al. (2016 Geochemical Journal)

Effective separation by hydrocyclone

Experiment of hydrocyclone The most promising area (105 km2) can provide
 50 to 800 times of the Japanese annual REE demand 1,400 to 2,400 times of the global annual supply (15–25 t) of Sc

REE-rich mud is a unique resourcethat can serve both HREE and Sc

Grain-size separation enables
 to improve REE grade by 2.6 times to reduce mud volume to 20–50%

Development system of REE-rich mud
Transportation(Leaching solution,Residual mud, etc.)

REE FPSO(Floating Production Storageand Offloading System）

TankerSupport vessel

Leaching of REE by HCl
Acid diluted with seawater
Leaching on the ship

Residual mud is used for
landfill of remote islands

Airlift system tolift REE-rich mud

Neutralization with NaOH
turns remaining acid into “salt”
HCl + NaOH → “NaCl” + H2O

AUV

ROV

Under water backhoe
Subsea mining byUnder water backhoeConsortium for promotion of REE-rich mud development
Development systemof REE-rich mud
The Universityof Tokyo

Mitsui Ocean
Development& Engineering

SANTOKU

Shin-Etsu
ChemicalTOA
Corporation

IHI

Mitsui
Mining &Smelting

FURUKAWA

Nippon Yusen
Kaisha LINE

Komatsu

Showa
Denko

TOYOTA
MOTOR

MitsuiO.S.K.
Lines

Kawasaki
Kisen
Kaisha

FUKADA
Salvage &Marine Works

Sumitomo
MitsuiConstruction

KAJIMA
Corporation

Taiheiyo
CementJX Nippon
Mining &Metals/ENEOS

JAPAN
NUS

Industrial
GrowthPlatform

Nippon Steel
ResearchInstitute

PwC

The Japan
Research anddevelopment
Center for Metals

UACJ

AGC

TDK

NEMOTOYAMAGIWA

Mitsubishi
Heavy
Industries

applause

The Ota City
IndustrialPromotion
Organization

Office of
DesignatedRemote Island
Ports, MLIT

Chiba
Institute ofTechnology

Tokyo
Institute ofTechnology

AoyamaGakuinUniversity

Japan Agency forNational
Japan Oil, Gas
Development
Marine-Earth
Maritimeand Metals National
Bank of Japan
Science andResearch Institute Corporation[Observer]
Technology[Observer][Observer]

40 Japanese major companies and agencies join with great expectations
toward the first development of deep-sea mineral resources in the worldToward a “truly” sustainable development of mineral resources
On-land deposits can be easily mined by anyone⇒ Illegal and unregulated mining has occurred
Environmental pollution

Low environmental impact ofREE-rich mud development

Human rights violation(Child labor)

Hydrothermal vent(Seafloor sulfide deposit)Reuters(2020.6.28)

Reuters(2019.12.17)
Seafloor resources can be developed only by national agencies
and/or companies with high-level technologies and compliance

Pelagic seafloor(REE-rich mud)

Commonspecies(probablynoendemic species) live in pelagic areas⇒ Ecosystem can recover after mining

The mud itself is harmless, in contrast
to deep-sea oil, methane hydrate, orseafloor sulfide deposits
Effective airlift system can inhibit
spreading mud into surrounding
seawaterDevelopment of REE-rich mud is in line with the directionof the international community and the SDGs

Advanced REE materials will open the way to the future
Al-Sc alloy

SOFC

Gd-fullerenols
Luminescent
REE complexes

3D printed bike by
Al-Sc-Mg alloy

High-luminance long afterglow

phosphorescent pigment

Polarized
luminescence film

Oxide Scintillator

Toward a sustainable future with REE-rich mud