0

1

2

　 　 　 　 　

Exp. # Chlorinating agent, i

Mass of chlorinating agent i, wi / g

Amount of element in the chlorinating agent j, Mj / mol

Cu Cla CuCl2 4.028 0.03 0.06b CuCl2 5.944 0.06 0.06

CuCl (l)

PtCu (s)

0

-30

-20

-10

0

-30

-20

-10

-20

-10

log

pC

l 2

log a Ptlog a

Cu

PtCl2

Cu-Pt-Cl systemT = 873 K

Pt (s)

Cl2 (g)

Cu (s)

New Separation and Recovery Process of Platinum Using Chlorinating Agents

Chiyoko Horike and Toru H. Okabe* Graduate Student, Graduate School of Engineering, The University of Tokyo; *Institute of Industrial Science, The University of Tokyo,

Introduction(Global scale, 2006) Typical recovery process

Thermodynamic analysis

Results and Discussion Conclusion

Purpose of this study

Development of a new process for an effective recovery of PGMs from scrap

Mg － Pt compounds and Pt were reacted with a chlorinating agent (CuCl2 or CuCl) at 873 K for 3 h.

XRD analysis

・　 Cl can be supplied by dissociation of chloride salts.・　 Mg can be chlorinated faster than Pt.・　 CuCl2 is dissociated into Cl2 and CuCl around 873 K.・　 Vapor pressure of CuCl is lower than 10-4 atm.

Experimental

Demand & Supply

Chlorination apparatusSynthesis of Mg － Pt compounds

Stainless steel reaction vessel

Ta crucible

Pt plate

Stainless steel plate

Ti sponge

TIG welding

Stainless steel cover

Mg block

Pure Pt was reacted with molten Mgat 1173 K for 12 h. → Homogeneous Mg － Pt compounds were formed. (SEM, EDS, XRD)

① 　 Compound formation under a highly 　　 reducing atmosphere　　 →　 Pretreatment for selective and 　 efficient dissolution of PGMs② 　 Chlorination

→ 　 High dissolution efficiency→ Smaller amounts of acids required for dissolution→ 　 Fast dissolution

Che

mic

al p

oten

tial o

f ch

lorin

e

③ 　 [PtCl6]2–

Oxidation/Dissolution

② 　 PtClx 　Chlorination

① 　 R － Pt 　　 (R: reactive metal)

pCl2

Pttprocess

Short dissolution time

South Africa ：165 t (69%)

Automotivecatalyst ：131 t (55%)

Russia ：27 t (11%)

North America ：11 t (4%)

Other

Recovery from automotive catalyst ： 27 t (11%)

Chemical ：11 t (5%)

Electrical ：13 t (6%)

Jewelry ：50 t (21%)

Other

(a) Demand of Pt : 239 t (b) Supply of Pt : 240 t

1980 1990 2000 2010 2020 20300

100

200

300

400

500

600

700

Ma

ss o

f pla

tinu

m, w

Pt /

t

Demand

Recovery

Estimate

Year

World demand and recovery for Pt

Waste solution

Residue

Scraps containing PGMs (M)

Mg vapor treatment

Mg － M compounds

Chlorination

MClx

Dissolution

Solution containing PGMs

PGMs recovery

Pure PGMs

Reactivemetal (R)(R: Mg)

Chlorinating agent (CuClx)(X = 1, 2)

HCl aq.

(M: Pt, etc.)

This study

Flowchart of the new process

Vapor pressure of selected metals and chlorides

Ellingham diagram

0.8 1.0 1.2 1.4 1.6 1.8 -20

-16

-12

-8

-4

0

Reciprocal temperature, 1000 T-1 / K-1

Va

por

pre

ssur

e, l

og

pi (

atm

)

Pt

Cu

CuCl

FeCl3

Mg

873 K 673 K

FeCl2

MgCl2

MgCl2 ・ 6H2O# 25-0515

CuCl # 06-0344

Pt # 04-0802

1 cm 10 20 30 40 50 60 70 80 90

Inte

nsi

ty, I

(a

.u.)

Angle 2θ / degree

Exp. # (a) Chlorination by CuCl2 for Mg － Pt

10 20 30 40 50 60 70 80 90

Exp. # (b) Chlorination by CuCl for Mg － Pt

Inte

nsi

ty, I

(a

.u.)

1 cm Angle 2θ / degree

　 　 　 　 　 　 　

Exp. # sample Chlorinating agent, i

Composition of element k, Ck (mass%)*

Mg Pt Cu Cl

－ Mg － Pt － 13.6 67.0 00.0 －

aChlorinated

Mg － PtCuCl2 10.7 47.6 04.8 Bal.

bChlorinated

Mg － PtCuCl2 07.1 36.1 17.0 Bal.

Composition analysis

* Determined by ICP-AES analysis.

The amount of Pt with an oxidation state of two was determined by calculation.　　 Exp. # (a) 　 20%Pt　　 Exp. # (b) 　　　78%Pt

Pt can form complex compounds.

Sta

nd

ard

Gib

bs e

ne

rgy

of f

orm

atio

n, Δ

Gf゜

/ k

J・

(mol

・C

l 2)-1

Temperature, T / K

400 500 600 700 800 900 1000-600

-500

-400

-300

-200

-100

0

PtCl3 PtCl2CuCl2

FeCl3

FeCl2

CuCl

MgCl2

673 K 873 K

・　 Reaction temperature was determined at 873 K.

・　 CuCl2 and CuCl were selected

for the chlorinating agent.

Potential diagramWeight measurement

Rat

io o

f w

eigh

t, R

Comparison of weight change

Ratio of weight, R = wo,i / wf,i

wf,i : Weight of the feed sampleswo,i: Weight of the obtained samples

Mg alloying of Pt was clearly effective for the reaction with CuClx (x = 1, 2).

Mg － Pt PtMg － Pt Pt

Exp. # (a)CuCl2

Exp. # (b)CuCl

0.4

03

g

0.3

99

g

0.3

98

g

0.4

01

g

0.6

28

g

0.3

98

g

0.7

51

g

0.4

75

g

Chlorination condition

Pyrometallurgical process ○ High efficiency & speed × High energy cost & large facilitiesHydrometallurgical process ○ Low energy cost & easy handling × Long processing time & generation of a large amount of waste solution

Cu3Pt # 35-1358

A fundamental technique that utilizes the

selective alloying of PGMs with collector

metals followed by chlorination/oxidation was

studied.

・　 Mg － Pt compounds and Pt were

chlorinated by using a chlorinating agent

(CuCl2 or CuCl) at 873 K for 3 h.

・　 Mg alloying of Pt was clearly effective for

the reaction with CuClx (x = 1, 2).

・　 After chlorination for Mg － Pt by CuCl2,

MgCl2 and pure Pt were formed, and the

obtained sample was contaminated by CuCl.

・　 After chlorination for Mg － Pt by CuCl,

Cu3Pt was formed.

・　 Development of new supplying method of

CuClx (x = 1, 2) for more effective

chlorination of Pt.

・　 Integration of the proposed chlorination

method with the conventional dissolution

methods in order to investigate practical

processes.

Future work

vacuum

Quartz tube

Heater

Glass wool Quartz crucible

Powder of Mg － Pt

Pt powder

Chlorination agent (CuCl2 or CuCl)

300

600

900

873 KTe

mpe

ratu

re,

T /

K

Scrap containing precious metals (M)

Pretreatment (Crushing, etc.)

Cu, Pb, Fe, etc.

Extraction by collector metals

Collector metal containing M

Dissolution in acid

Separation and purification

Recovered precious metals

Dire

ctly

dis

solv

ed in

aci

d

Pyrometallurgical

process

Hydrometallurgical process