Exp. # Chlorinating agent, i Mass of chlorinating agent i, w i / g Amount of element in the...
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Transcript of Exp. # Chlorinating agent, i Mass of chlorinating agent i, w i / g Amount of element in the...
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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