Prospects for Rare Earth Elements From Marine Minerals

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ProspectsforRareEarthElementsFromMarineMinerals

Rareearthelements (REEs)composethe lanthanidegroupof15elements in theperiodic table,14ofwhich

occur in nature and one that does not occur in nature, promethium. Scandium and yrium are usually

considered togetherwith theREEsbecauseof their similargeochemical characteriscs.Despite theirname,

REEsarerelavelyabundantintheearth'scrust.However,becauseoftheirgeochemicalproperes,rareearthelementsaretypicallydispersedandnotcommonlyfoundinconcentratedandeconomicallyexploitableforms.

Theirindustrialusesinemerginghigh andgreentechnologyapplicaonsgivethemanimmediatecricaland

strategicimportance.

BriefingPaper02/12

JimHein|May2012

www.isa.org.jm

Table1:RareEarthElements

This paper was prepared for the Internaonal Seabed Authority sensizaon seminar held in New York on 16 February 2012

on the work of the ISA and current issues relang to deep seabed mining. Dr. James Hein is a senior scienst with the United

States Geological Survey (USGS) in California. He is also an Adjunct Professor of Ocean Sciences at the University of California

at Santa Cruz. He has authored or coauthored more than 400 papers and abstracts.

Element Symbol Selected Applicaons

ScandiumSc Superalloys,lightaerospacecomponentsXraytubes,

catalysts

Yrium

Y Ceramics,metalalloys,medicaluses,rechargeable

baeries,phosphorsforTVshightemperature

superconductors

Lanthanum La

Baeries,

opcal

glass,

camera

lenses,

catalysts

for

petroleumrefining

Cerium Ce Catalysts,metalalloys,radiaonshielding

Praseodymium Pr Magnets,lasers,pigments,cryogenicrefrigerant

Neodymium Nd Highstrengthpermanentmagnets,lasers

Promethium Pm Nuclearbaeries,guidedmissiles

SamariumSm Hightemperaturemagnets,reactorcontrolrodsand

neutronshielding,lasers

Europium Eu Liquidcrystaldisplays,fluorescentlighng

GadoliniumGd Magnecresonanceimagingcontrastagent,memory

chips

TerbiumTb Greenphosphors,lasers,fluorescentlamps,opcal

computermemories

DysprosiumDy Permanentrareearthsmagnets,lasers,catalysts,

nuclearreactors

Holmium Ho Lasers,nuclearreactors,catalysts

Erbium Er Lasers,vanadiumsteel,infraredabsorbingglasses

Thulium Tm PortableXraymachines

YerbiumYb Infraredlasers,chemicalreducingagent,rechargeable

baeries

Luteum Lu

PETScan

detectors,

superconductors,

high

refrac

ve

indexglass

Chinacurrentlyproducesover

95percentoftheworld'sREE

supplyandhasrecentlystarted

torestrictexports,becausethe

REEproduconisbeingmore

directedtodomescuseandis

beingconservedforfutureuse.

TheusesofREEinmodern

socieesareextensiveand

includehybridandelectric

cars,windturbines,weapons

systems,motors,magnetsfor

manyapplicaons,andahuge

marketforphosphorsincolour

televisionsandmonitors,

amongmanyother

applicaons.Theautomobile

manufacturersworldwidecannotoperatewithoutthe

availabilityofREEs.Withinthe

groupofREEs,anumberof

elementsareparcularly

cricalandpredictedtobein

deficitontheglobalmarketby

2014,forexampleneodymium,

europium,terbiumand

dysprosium(IMCOA,20111and

othersources).


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Figure1: Historyofrareearthelementproduction (fromUSGS)

g

Figure2:PolymetallicnodulesexplorationlicensesandreservedareasinClarionClippertonFractureZone(MapISA)

richcrustsintheAtlancandIndian

Oceansareexpectedtobeasrichin

REEcontentasinthePacific,butdataandknowledgeforthoseareas

remainpoortodate.

Polymetallicnodulesaresmallgolf

ballsized concreonsthat sitonthe

sedimentsurfaceondeepwater

(4,5006,500meters)abyssalplainsof

theglobalocean(Figure 4).Theyare

composedpredominantlyof

manganeseandironoxideswith

muchlesseramountsofcopper,

nickel,cobalt,REEs,lithium,and

molybdenum.Themainmetalsare

derivedfromcoldambientseawater

andfromporewatersinthe

sediment. Theminormetalsare

adsorbedontothemajorironand

manganesephases. Crustsformpavementsonhardrocksubstrates

onsubmarineseamountsandridges

throughouttheglobalocean(Figure

5).Thoseofeconomicinterestoccur

atwaterdepthsofabout1,0002,500

meters.Theyarecomposed

predominantlyofmanganeseand

ironoxides,cobalt,nickel,REEs,

tellurium,molybdenum,zirconium,

tanium,bismuth,niobium,planum,

andtungsten.Themetalsofinterestarederivedfromcoldambient

seawaterandareadsorbedontothe

majorironandmanganesephases.

Upunlthe1990s,theUSAwas

themainproducerofREEs,which

camefromtheMountainPass

mineinCalifornia(Figure1). This

mineclosedin2002astheresult

ofcompeonfromtheChinese

BayanObomine,theworlds

largest

REE

deposit.

Because

of

thereduconinexportsfrom

China,theMountainPassmine

willreopenin2013andseveral

newlydevelopingmineswill

comeonlineduringthenext

years,suchasinAustralia,South

Africa,andelsewhere. Itmay

takeunlabout2016beforenew

REEsourcesmakeupforthe

reduconsinChineseexports.

NewconsideraonsfortheaugmentaonofREEsupplies

comefromtheREEsinthevery

largetonnagedeepocean

mineraldeposits,specifically

polymetallicnodulesandcobalt

richcrusts. Bothdeposittypes

haveasignificantpotenalto

supplyREEstothemarketplace

asabyproductoftheextracon

ofcopper,nickel,cobalt,and

manganese.Eventhoughthegrades(concentraonofREEs)of

themarinedepositsaregenerally

lowerthanforthelandbased

deposits,thetonnagesaremuch

greaterthanthelandbased

deposits.Thisistrueeven

consideringthatthereareonly

twoprimemineraldepositareas

inthePacificOcean:TheClarion

ClippertonnodulezoneintheNE

Pacificintheinternaonalseabedarea,wherenine

exploraoncontractsare

presentlyinforce(Figure 2);and

theprimeequatorialPacificcrust

zone,whichincludesboththe

internaonalseabedareaand

ExclusiveEconomicZonesof

PacificIslandcountries(Figure 3).

Crusts,onaverage,exhibitabout

three meshigherREE

concentraonsthannodulesand

someofthedepositshavesimilar

concentraonstothelandbased

oresinSouthernChina.Itis

worthwhilenongthatcobalt


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ProspectsforRateEarth ElementsfromMarineMinerals

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Figure 3:Map of most permissive area for cobaltrich crusts in the global ocean, located in

the western equatorial Pacific (from Hein et al., 2009)2

Figure4: (Left)Polymetallicnodules(fromHeinandKoschinsky,2012)3;Figure 5: (Right) Photo of seabed at 2,000m water

depth showing crust pavement (below) and crusts recovered in the Marshall Islands area (from Hein and Koschinsky, 2012)3

Anaddionaladvantageofthemarinedepositsisthat

itissaidtotake1,000stepstoprocessalandbased

oretoisolateoneoftheHREEs.Incontrast,because

theREEsareadsorbedontothemainironand

manganesephases,theycanbedissolvedfromseabed

oresusingrelavelysimpleprocedures(diluteacid

leach)inamorecostefficientway.

Athirdadvantagerelatestoseveralenvironmental

consideraons.Themajorlandbaseddepositshave

highconcentraonsoftoxicwasteproducts(thorium)

thatneedtobecarefullymanaged. Apossible

advantageofseabeddepositsistheabsenceofsuch

radioacvecomponentsinthedepositsthat

significantlyincreasethetechnologicalcomplexityand

costsofREEprocessingonland.Amoveablemining

plaormformarinedepositsallowfortheminingof

justthehighgrade,hightonnagedepositsthereby

impacngtheleastamountofseabednecessarywithin

acrustornodulezone.Deepoceananimalpopulaon

densiesarealsogenerallylow.

Anotherenvironmentaladvantageisthatlandbased

minesleaveasubstanalfootprintintermsof

infrastructureattheminesite,whereasmarine

depositsdonothaveseabedinfrastructureandonly

theseabedminerimpactstheseabed.Landbased

minescommonlyrequiretheremovalofsignificant

amountsofbarrenoverburdenrock,24 mesmore

thanthesizeoftheorebodyitself.Incontrast,marine

depositssitattheseabedwithnooverburdento

remove.

Thereareseveralpossible

advantagestominingthe

marinedepositsinorderto

augmenttheproducon

fromlandbaseddeposits.

Themainmessageisthatthe

economical,geologicalandenvironmentalfactorsfor

landbasedandmarine

depositsneedtobe

evaluatedonequalfoong.

Economically,therelave

contentoftheparcularly

interesngheavyREEs

(HREEs)ishigherinseabed

depositsthaninthelargest

landbasedREEmines,for

examplethelargestREE

mine,BayanObo(China)and

thesecondlargest,Mountain

Pass(USA).Bothlandbased

depositsmenonedabove

containlessthan1%HREEs

(percentageoftotalREEcontent),

whereastheCCZnoduleshavea

relavecontentof10%HREEsandPacificcrustsaveragemorethan6.3%

HREEs.ThesmallerlandbasedREE

deposits,forexampletheion

adsorponclaysinSouthernChina,

havesimilarHREEconcentraonsas

foundinthemarinedeposits.

ComparingtheCCZnodulesandPacific

primecrustswiththesetwolargest

exisnglandbasedREEmines,thelandbaseddepositsaregenerallyhigherin

gradebutlowerintonnageofore.

Howeverthecontainedmetal(REEs)in

thecrustsandnodulesiscomparableto

thoseintheBayanOboandMountain

Passdeposits,respecvely.


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Endnotes1 IndustrialMineralsCompanyofAustralia.(2011).In:Smith,M. Rare earth minerals: The indispensable resource for clean energy

technologies.2 Hein,J.R.,T.A.Conrad,andR.E.Dunham.(2009). Seamountcharacteriscsandminesitemodelappliedtoexploraon andmining

leaseblockseleconforcobaltrichferromanganesecrusts. Marine Georesources and Geotechnology, 27 (2), 160176.3 Hein,J.R.andA.Koschinsky.(2012).Deepoceanferromanganesecrustsandnodules. InSco,S.,(ed.)The Trease on

Geochemistry,v.12.Elsevier(inpress).4

Halbach,P.,G.FriedrichandU.vonStackelberg(1988).The Manganese Nodule Belt of the Pacific Ocean.Stugart:FerdinantEnke.5 Mukhopadhyay,R.,A.K.GoshandS.D.Iyer.(2008).The Indian Ocean Nodule Field: Geology and Resource Potenal.London:

Elsevier.

ISATechnicalStudyDeepocean deposits may offer a paral soluon to

projected shortages of REEs. In 2011 the Authority

commenced work on a technical study designed to

address the queson of whether sea floor deposits

have the potenal to become an alternave source of

REEs. During the first phase of the project, the

geochemical properes of REEs and their geographic

variaon are being examined in detail. Inially, a

global geochemical database of trace metal grades

with approximately 2,000 analysed samples, thereof

about 700 REE samples has been compiled from

various sources, covering the major geographic areas

of interest for cobaltrich crusts and the major

polymetallic nodule provinces, including the Central

Pacific, the Central Indian Ocean, the Peru Basin, the

Penrhyn Basin, the Manihiki Plateau, the Rio Grande

Seamounts and other areas of potenal interest. The

geochemical analyses of metal contents carried out to

date in the context of the project are promising, not

considering metallurgical factors and processing costs

in detail at this stage.

Generally, the extracon of REEs from tailings and

interim products may represent a costefficient way to

produce REEs compared to landbased producon,

without a negave effect on the producon of the main

metals because iron is not a target metal; REE by

product operaons could turn such residues into

profits. An important working hypothesis is that REEs

might be parcularly enriched in ironhydroxide

bearing tailings and the grades in these tailings may

exceed the grades of the REE deposits mined in China.

Relevant nodule processing flowsheets with interim

products can be found in Halbach et al. (1988)4

and in

Mukhopadhyay et al. (2008)5.

InternaonalSeabedAuthority,1420PortRoyalStreetKingston,Jamaica

Tel:+18769229105 |Fax:+18769220195

Website:www.isa.org.jm

The Internaonal Seabed Authority is an autonomous internaonal organizaon established under the 1982 United Naons

Convenon on the Law of the Sea and the 1994 Agreement relang to the Implementaon of Part XI of the United Naons

Convenon on the Law of the Sea. The Authority is the organizaon through which States Pares to the Convenon shall, in

accordance with the regime for the seabed and ocean floor and subsoil thereof beyond the limits of naonal jurisdicon (the

Area) established in Part XI and the Agreement, organize and control acvies in the Area, parcularly with a view to adminis

tering the resources of the Area.

As part of its mandate to conduct resource assessments of prospecve mineral deposits in the Area, the Authority, together

with its contractors and sciensts, joined forces with a group of technical experts to establish and develop a Geological Modelof polymetallic nodule deposits in the ClarionClipperton Fracture Zone. The publicaon (A Geological Model of Polymetallic

Nodule Deposits in the ClarionClipperton Fracture Zone: ISA Technical Study No. 6) is available online on www.isa.org.jm/files/

documents/EN/Pubs/GeoModweb.pdf.

The Geological Model consists of a set of digital and hard copy maps and tables describing the predicted metal content abun

dance of deposits in the CCZ, along with associated error esmates. The Prospectors Guide examines all potenal proxy data

variables idenfied as important indicators of metal content and abundance, and outlines specific data sets that qualify for use

in the Geological Model.

The Internaonal Seabed Authority is an autonomous internaonal organizaon established under the 1982 United Naons

Convenon on the Law of the Sea and the 1994 Agreement relang to the Implementaon of Part XI of the United Naons

Convenon on the Law of the Sea. The Authority is the organizaon through which States Pares to the Convenon shall, in

accordance with the regime for the seabed and ocean floor and subsoil thereof beyond the limits of naonal jurisdicon (the

Area) established in Part XI and the Agreement, organize and control acvies in the Area, parcularly with a view to adminis

tering the resources of the Area.

As part of its mandate to conduct resource assessments of prospecve mineral deposits in the Area, the Authority, together

with its contractors and sciensts, joined forces with a group of technical experts to establish and develop a Geological Modelof polymetallic nodule deposits in the ClarionClipperton Fracture Zone. The publicaon (A Geological Model of Polymetallic

Nodule Deposits in the ClarionClipperton Fracture Zone: ISA Technical Study No. 6) is available online on www.isa.org.jm/files/

documents/EN/Pubs/GeoModweb.pdf.

The Geological Model consists of a set of digital and hard copy maps and tables describing the predicted metal content abun

dance of deposits in the CCZ, along with associated error esmates. The Prospectors Guide examines all potenal proxy data

variables idenfied as important indicators of metal content and abundance, and outlines specific data sets that qualify for use

in the Geological Model.

The area of interest for this study is 110o160

oW longitude and 0

o20

oNorth latude

Prospects for Rare Earth Elements From Marine Minerals

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