Download Ti ore chlorination

Iron Removal from Titanium Ore
by Electrochemical Method
Isao Obana1 and Toru H. Okabe2
1Graduate
School of Engineering,
The University of Tokyo
2International
Research Center for Sustainable Materials,
Institute of Industrial Science, The University of Tokyo
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
1
Introduction
Features of titanium
Applications
Lightweight and high strength
Corrosion resistant
Biocompatible
Some titanium alloys： shape memory effect
superelasticity
Aircraft
Spacecraft
Chemical plants
Implants
Artificial bones, etc.
The Kroll process: Currently employed Ti production process
Mg & TiCl4
Feed port
Reaction
Container
Sponge
Titanium
MgCl2
Chlorination
Ti ore + C + 2 Cl2 → TiCl4 (+ FeClx) + CO2
Reduction
TiCl4 + 2 Mg
→ Ti + 2 MgCl2
Electrolysis
MgCl2
→ Mg + Cl2
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
2
Upgrading Ti ore
Others
FeOx
Upgrade
FeOx
TiOx
Upgraded Ilmenite (UGI)
(FeTiOX)
(CaCl2)
Selective chlorination
Upgraded Ti ore
Ti metal
FeClx Ti scrap
(+AlCl3)
Chlorine recovery
Fe
Discarded
Advantages:
Low grade Ti ore MClx
Ti smelting
Chloride
wastes
TiOx
Ti ore (Ilmenite, FeTiOx)
(TiO2)
Others
TiCl4
1． Material cost can be reduced
by using low-grade ore.
2. Chlorine circulation in the Kroll
process can be improved.
3. This process can also be applied
to the new Ti production
processes, e.g., the direct
electrochemical reduction of TiO2.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Previous study
Vacuum pump
Pyrometallurgical de-Fe process
FeOx (s, in Ti ore) + MgCl2 (s, l) → FeClx (l, g) + MgO (s)
Condenser
Deposit
(FeClx)
Susceptor
Mixture of
Ti ore
and MClx
RF coil
Quartz Tube
N2 or N2+H2O gas
CaCl2 (s, l) + H2O (g)
→ HCl (g) + CaO (s)
FeOx (s, in Ti ore) + HCl (g) → FeClx (l, g) + H2O (g)
T = 973~1373 K
The selective chlorination of Ti ore
by MgCl2 or CaCl2 is found to be feasible.
Ref. R. Matsuoka and T. H. Okabe: Symposium on Metallurgical
Technology for Waste Minimization at the 2005
TMS Annual Meeting, San Francisco, California (2005.2.13–17).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Study objectives
Low-grade Ti ore
(FeTiOx)
Fe removal by
selective chlorination
TiO2 + flux
Direct reduction of TiO2
obtained after Fe removal
Application of
electrochemical method
using molten salt
Ti powder
1. Thermodynamic analysis of selective chlorination
2. Fundamental experiments of selective chlorination
by electrochemical methods
3. Reduction experiment for the sample obtained by
selective chlorination
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Thermodynamic analysis (Ti ore chlorination)
Fe-Cl-O and Ti-Cl-O system, T = 1100 K
Oxygen partial pressure, log pO2 (atm)
0
Potential region
for selective chlorination
of iron from titanium ore
Fe2O3 (s)
–10
TiO2 → Stable
FeOx → FeClx (g)
Fe3O4 (s)
CO/CO2 eq.
C/CO eq.
–20
TiO2 (s)
H2O (g)/HCl (g) eq.
FeO (s)
–30
–40
MgO (g)/MgCl2 (l) eq.
CaO (s)/CaCl2 (l) eq.
aCaO = 0.1
FeCl2 (l)
TiO (s)
Fe (s)
FeCl3 (g)
–50
TiCl3 (s)
Ti (s)
–60
-40
Potential region
for chlorination
of titanium
TiCl4 (g)
TiCl2 (s)
-30
-20
-10
0
Chlorine partial pressure, log pCl2 (atm)
Ti ore : FeTixOy
For simplicity, it is
assumed to be a
mixture of TiOx and FeOx
The selective chlorination
of Ti ore by controlling
chlorine partial pressure
may be possible using an
electrochemical technique.
Fig. Chemical potential diagram for Fe-Cl-O and Ti-Cl-O systems at 1100 K
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Chlorination by increasing Cl2 potential
Electrolysis
Cathode：
Fen+ + n e– → Fe
Ca2+ + 2 e– → Ca
FeCl3, AlCl3,
O2, CO2 gas
DC power source
e–
Anode:
2 Cl– (in CaCl2) → Cl2 + 2 e–
FeOx + Cl2
→ FeClx↑ + O2–
Molten salt
(CaCl2, MgCl2, etc.)
Upgraded or
low-grade Ti ore
(e.g., FeTiOx)
Chlorine chemical potential in molten CaCl2 at anode
can be increased electrochemically.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Theoretical decomposition voltage
Table Standard Gibbs energy of decomposition and theoretical voltage of that in several chemical
species at 1100 K.
Reactions
CaCl2 (l) = Ca (l) + Cl2 (g)
D G o/kJ mol-1a
629
FeO (s) = Fe (s) + 1/2 O2 (g)
D E o/Va
3.26
201
1.04
3
0.02
FeO (s) + CaCl2 (l) + C (s) = FeCl2 (l) + CO (g) + Ca (l)
409
2.23
FeTiO3 (s) + CaCl2 (l) + 1/2 C (s)
= TiO2 (s) + FeCl2 (l) + Ca (l) + 1/2 CO2 (g)
438
2.34
FeO (s) + 1/2 C (s) = Fe (s) + 1/2 CO2 (g)
a: I. Barin: Thermochemical Data of Pure Substances, 3rd ed.
(Weinheim, Federal Republic of Germany, VCH Verlagsgesellschaft mbH, 1997)
Under a certain condition,
the selective chlorination of Fe in Ti ore may proceed
below the theoretical decomposition voltage of CaCl2.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Low-grade Ti ore
(FeTiOx)
Fe removal by
selective chlorination
TiO2 + flux
Direct reduction of TiO2
obtained after Fe removal
Iron removal by
selective chlorination
using an electrochemical
method
Ti powder
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Experimental apparatus
(a) Reaction chamber
(b) Reaction cell
V
A
Potential lead (Nickel wire)
Stainless steel tube
(Electrode)
Ar inlet
(a)
O.D. 19 mm
I.D. 17 mm
(b)
Rubber plug
Support rod
(Stainless steel tube)
Wheel flange
Air hole
Thermocouple
Screw (Stainless steel)
Heater
Mild steel crucible (Cathode)
Surface of molten salt
Graphite crucible (Anode)
Sample
Holes for
molten salt diffusion
Molten salt (CaCl2)
Graphite crucible
Ceramic insulator
Sample
(Ti ore, CaCl2, etc.)
Height 40 mm
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Selective chlorination experiments
Experimental conditions：
Temperature:
Atmosphere:
Molten salt:
Cathode:
Anode:
1100 K
Ar
CaCl2 (800 g)
Mild steel crucible (I.D. 96 mm)
Graphite crucible (I.D. 17 mm)
Sample
Mass of sample i, wi/g
Voltage, Time,
Ti ore
Carbon
E/V
t”/h
CaCl2
Exp. No. Ilmenite UGI
powder
A
4.00
ー
ー
ー
1.5
12
B
0.74
ー
2.17
ー
1.5
3
C
0.74
ー
2.17
0.18
1.5
3
D
ー
1.59
1.27
ー
1.5
3
E
ー
1.59
1.27
ー
2.0
3
Voltage monitor
/controller
e–
Molten
CaCl2
Mild steel
crucible
(Cathode)
Graphite crucible
containing Ti ore
(Anode)
Low initial Fe content
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Results of the selective chlorination experiments
XRF analysis
Table Analytical results of the samples obtained
after electrochemical selective chlorination
Sample
Concentration of element
Fe/Ti
i, Ci (mass%)
ratio,
V RFe/Ti (%)
Ti
Fe
Ca
Si
Ilmenite
Exp. A
Exp. B
Exp. C
Exp. X
42.6
45.7
47.2
30.2
45.1
48.7
21.7
3.4
7.5
5.8
0.3
12.3
47.9
42.7
40.6
2.2
1.4
0.0
0.3
0.5
UGI
95.9
1.9
0.1 0.1 0.2
2.00
Exp. D
Exp. E
98.0
96.9
0.2
0.3
0.1
0.2
0.18
0.28
0.6 114
2.7 47.4
0.4
7.2
0.1 24.7
0.1 12.9
0.3 0.5
0.5 0.2
Fe/Ti ratio decreased
from 114% to 7.2% (ilmenite)
and from 2.00% to 0.18% (UGI).
94% of Fe in ilmenite
and 92% of Fe in UGI
were successfully
removed.
a: Average values of the samples obtained from
the upper and lower parts of the graphite crucible
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Result of a selective chlorination experiment
Discussion
XRD analysis
Intensity, I(a. u.)
Ilmenite
FeTiO3
FeTiO3 (s) + CaCl2 (l)
→ CaTiO3 (s) + FeClx (l, g)
:CaTiO3
:TiO2
10
20
30
40
50
60
70
80
Angle, 2θ (degree)
90
100
Fig. XRD pattern of the start sample and
the sample obtained after Fe removal (Exp. B)
A mixture of CaTiO3 and TiO2
was obtained after Fe removal.
FeTiO3 (s) + CaCl2 (l) + C (s)
→ TiO2 (s) + FeClx (l, g) + COx (g) + Ca (s)
CaTiO3 can be utilized
as a feed material of
direct TiO2 reduction
processes
(e.g., FFC, OS, EMR-MSE
processes).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Low-grade Ti ore
(FeTiOx)
Fe removal by
selective chlorination
TiO2 + flux
Direct reduction of TiO2
obtained after Fe removal
Ti powder
Direct reduction
of TiO2 after
Fe removal
by electrochemical
method
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Reduction experiment apparatus
Direct reduction by electrochemical method was applied.
Carbon anode
Electrolysis
Cathode:
TiO2 + 4 e– → Ti + 2 O2–
Anode:
CaCl2 molten salt
Ti crucible
C + x O2– → COx + 2x e–
TiO2 feed
Fig. Schematic illustration of the experimental apparatus in this study.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Reduction experiments
Experimental conditions：
Temperature: 1100 K
Atmosphere: Ar
Molten salt:
CaCl2 (800 g)
Cathode:
Ti crucible
(I.D. 18 mm)
Anode:
Graphite rod
(O.D. 3 mm)
Table Analytical results of the sample obtained
after electrochemical selective chlorination
Sample
UGI
Exp. D
Exp. E
Exp.
Fe/Ti
Concentration of element i,
ratio,
Ci (mass%)
Fe Ca Si
Ti
V RFe / Ti (%)
95.9 1.9 0.1 0.1 0.2
2.00
98.0 0.2 0.1 0.3 0.5
0.18
96.9 0.3 0.2 0.5 0.2
0.28
Mass of element i, wi / g
Ti ore CaTiO3 CaCl2
Voltage, Time,
E/V
t”/h
R-1
ー
1.50
2.50
1.5
3
R-2
ー
1.50
2.50
3.0
3
R-3
0.79
ー
2.50
3.0
3
R-4
0.76
ー
2.50
3.0
3
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Result of the reduction experiments
Ti reduction by EMR
XRD analysis
10
: Ti
Intensity, I (a.u.)
Intensity, I(a. u.)
:Ti2O
:CaTiO3
10
20
30
40
50
60
70
80
Angle, 2θ (degree)
Fig. XRD pattern of the sample obtained
after the reduction experiment (Exp. R-2)
CaTiO3 was changed into Ti2O
during this reduction experiment.
A complete reduction was
not achieved in this study.
90
100
20
30
40
JCPDS # 44-1294
50
60 70 80
Angle, 2q (degree)
90 100
Fig. XRD pattern (Cu-K) of the obtained
powder sample after reduction at 1173 K
using the EMR process.
Current monitor
Carbon anode
ee-
CaCl2 molten salt
2500 ppm O
In a previous study,
low oxygen
titanium powder
was obtained.
TiO2 preform (Cathode) Ca-X alloy
Ref. T. Abiko, I. Park, and T.H. Okabe, Proceedings of 10th World Conference
on Titanium, Ti-2003, (Hamburg, Germany, 13–18 July 2003), 253–260.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Summary
Low-grade Ti ore
・The selective chlorination of
Ti ore by using an electrochemical
method was investigated,
and 94% of Fe was
successfully removed directly
from low-grade Ti ore.
・The feasibility of Ti smelting
process for directly producing
metallic Ti from low-grade Ti ore
was demonstrated.
(FeTiOx)
Iron removal by
selective chlorination
TiO2 + flux
Reduction by
electrochemical method
Ti powder
Development of
an industrial scale process
for producing
low-cost titanium
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Question
and
Answer
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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History of Titanium
1791 First discovered by William Gregor, a clergyman and amateur
geologist in Cornwall, England.
1795 Klaproth, a German chemist, gave the name titanium to an
element re-discovered in Rutile ore.
1887 Nilson and Pettersson produced metallic titanium containing
large amounts of impurities.
1910 M. A. Hunter produced titanium with 99.9% purity by the
sodiothermic reduction of TiCl4 in a steel vessel.
(119 years after the discovery of the element)
1946 W. Kroll developed a commercial process for the production of
titanium: Magnesiothermic reduction of TiCl4...
Titanium was not purified until 1910,
and was not produced commercially until the early 1950s.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Titanium Production
China
4 kt
Kazakhstan
9 kt
Russia
26 kt
USA
8 kt
Total
65.5 kt
Japan
18.5 kt (28% share)
(b) Transition of production volume
of titanium mill products in Japan.
Amount of titanium
mill products [kt]
(a) Production of titanium
sponge in the world (2003).
18
16
14
12
10
8
6
4
2
0
1960
17.4 kt (2004)
1970
1980
1990
2000
Year
Fig. Current status of titanium production,
(a) production of titanium sponge in the world (2003),
(b) transition of production volume of titanium mill
products in Japan.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Table Comparison between common metals
and titanium.
Titanium
Symbol
Melting point (K)
Density (g / cc @298 K)
Specific strength
((kgf / mm2) / (g /
Clarke numbera cc))
Price (Yen / kg)
Production volume
(106 ton / year・world)
Aluminum
Iron
Ti
1943
4.5
Al
933.3
2.7
Fe
1809
7.9
8 ~ 10
3~6
4~7
0.46 (rank 10) 7.56 (rank 3) 4.7 (rank 4)
3000
600
50
~ 0.1
20
800
a: Values in parentheses are the
existence rank in the earth’s crust.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Flowchart of the titanium production
Ti feed (TiO2)
Chlorine (Cl2)
Reductant (C)
Chlorination
CO2, FeClx,AlCl3 etc.
Crude TiCl4
H2S etc.
Distillation
Other compounds
Pure TiCl4
Reductant, Mg
Reduction
Sponge Ti + MgCl2 + Mg
Vacuum distillation
Electrolysis
MgCl2
MgCl2 + Mg
Sponge Ti
Crushing / Melting
Ti ingot
Fig. Flowchart of
the titanium production
based on the Kroll process.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Composition of titanium ore
(a) Low grade titanium ore (ilmenite)
Others
10%
FeOx
45%
(b) Up-graded titanium ore (UGI)
Others
3%
FeOx
2%
TiOx
45%
TiOx
95%
Fig. (a) Composition of low grade titanium ore (ilmenite),
and (b) that of up-graded titanium ore
(up-graded ilmenite, UGI).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Upgrading Ti ore for minimizing chloride wastes
Others UpgradeFeOx
FeOx
TiOx
Ti ore (Ilmenite, FeTiOx)
Others
Chloride
wastes
TiOx
Upgraded Ilmenite (UGI)
Discarded
1. A large amount of chloride wastes (e.g., FeClx) are
produced in the Kroll process.
2. Chloride waste treatment is costly, and it causes
chlorine loss in the Kroll process.
Importance
1. Reduction of disposal cost of chloride wastes
2. Minimizing chlorine loss in the Kroll process
3. Improvement of environmental burden
4. Reduction of material cost using low grade ore
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Refining process using FeClx
Advantages:
This study
Low-grade Ti ore MClX
(FeTiOX)
(Cl2)
Selective chlorination
Upgraded Ti ore
(TiO2)
FeClx
(+AlCl3)
Carbo-chlorination
TiCl4 feed
COx FeClx
(+AlCl3)
FeClx
Ti scrap
1. Utilizing chloride wastes
from the Kroll process
Chlorine recovery
2. Low cost Ti chlorination
Fe
TiCl4
3. Minimizing chlorine loss
in the Kroll process
caused by generation
of chloride wastes
Ti metal or TiO2 production
Effective utilization of chloride wastes
Development of a new environmentally
sound chloride metallurgy
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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The Benilite process
Ilmenite
Reductant (Heavy oil etc.)
Fe2+ / TiFe = 80~95%
Reduction (in kiln)
Reduced ore
HCl aq.
HCl vapor
(18~20% HCl)
Leaching (in digestor)
145C° (2.5 kg/cm2) *4 hr
*2 step
Leached ilmenite Water
Spray acid
Roasting
Filtration
TiO2
Fuel
Sol.
Calcination
(Synthetic rutile)
TiO2 95% TiO
2
1% TiFe
Iron oxide
(90% purity)
HCl
Absorber
HCl aq.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Fig. Flowsheet of
the Benilite process.
27
The Beacher process (WLS)
Ilmenite
Coal (low ash)
Air
Reduction (in kiln)
Reduced ore
Gas + particle
Screen
+1 mm
-1 mm
Cyclone
Particle
Gas
Mag. separator
Waste (Non. mag.)
Reduced ilmenite
NH4Cl
Air
Leaching
TiO2
H2SO4 aq.
Acid Leaching
TiO2
Iron oxide + Sol.
Thickener
Iron oxide
Filtering / Drying
Sol.
TiO2 (Synthetic rutile) TiO2 92~93%
TiFe 2.0~3.5%
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Fig. Flowchart of
the Beacher process.
28
Thermocouple
Cathode (stainless steel)
Ceramic tube
Alumina tube
TiO2 (CaCl2) + 4 e- → Ti + 2 O2- (CaCl2)
Anode lead wire (W)
Fused CaCl2 bath
or TiO2 (CaCl2) + 2 Ca → Ti + 2 CaO
Alumina crucible
TiO2 powder
Graphite crucible (anode)
Electric furnace
Fig. Electrochemical reduction of TiO2 in CaCl2.
(Ref. Mem. Fac. Eng., Nagoya Univ., 19, (1967) 164-166.)
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Carbon anode
Ti cathode
e-
Cl2
e-
COX
Ca2+
O (in Ti) + 2
e-
→
O2-
Cl-
(in CaCl2)
[O]
O2C
Cl-
O2-
Ca
Ca2+
O2Ca
Ca Ti
Ca2+
O2Ca2+
[O] in Ti
Ti
Ca2+
Cl-
CaCl2 molten salt
Fig. The principle of electrochemical deoxidization of titanium.
(Ref. Met. Trans. B, 24B, June, (1993) 449-455.)
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Titanium ore
Titanium reduction by FFCprocess
TiO2
Chlorination or
sulfate method
COx
C
Titanium oxide
TiO2
Molten salt
Cathode
Mixing with
Binder
Anode
TiO2 + 4 e- → Ti + 2 O2 (in CaCl2)
Recovery of
titanium electrode
Cathode
formation
Crushing
and leaching
Calcination
(TiO2 electrode)
Fig. Schematic illustration of
the procedure of the FFC process.
FFC titanium
(Ref. Nature, 407, 21, Sep. (2000) 361.)
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
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Production process under investigation
FFC Process (Fray et al., 2000)
OS Process (Ono & Suzuki, 2002)
TiO2 powder
e-
e-
Carbon anode
Carbon anode
Ca
TiO2
preform
CaCl2
molten salt
CaCl2
molten salt
TiO2 + 2 Ca → Ti + 2 O2- + Ca2+ (b1)
Electrolysis
Cathode:
Electrolysis
Cathode:
TiO2 + 4 e- → Ti + 2 O2Anode:
C + x O2- → COx + 2x e-
(a1)
(a2)
Ca2+ + 2 e- → Ca
Anode:
C + x O2- → COx + 2x e-
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
(b2)
(b3)
32
Production process under investigation
EMR / MSE Process (Electronically Mediated Reaction / Molten Salt Electrolysis)
Current monitor
/ controller
Carbon anode
e-
ee-
TiO2
e-
CaCl2 -CaO
molten salt
(a) TiO2 reduction
Ca-X alloy (X = Ag, Ni, Cu,・・・)
(b) Reductant production
Cathode:
TiO2 + 4 e- → Ti + 2 O2Anode:
Ca → Ca2+ + 2 e-
(c1)
(c2)
Electrolysis
Cathode:
Ca2+ + 2 e- → Ca
(c3)
Anode:
C + x O2- → COx + 2x e- (c4)
Over all reaction
TiO2 + C → Ti + CO2
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
(d)
33
(a) FFC Process (Fray et al., 2000)
(b) OS Process (Ono & Suzuki, 2002)
(C) EMR / MSE Process (Okabe et al., 2002)
TiO2 powder
Carbon
anode
e-
e-
Carbon
anode
Current monitor
/ controller
e-
e-
e-
Carbon anode
Ca
CaCl2
molten salt
CaCl2
molten salt
TiO2 preform
TiO2 + 2 Ca → Ti + 2 O2- + Ca2+ (b1)
Electrolysis
Electrolysis
Cathode:
Cathode:
TiO2 + 4 e- → Ti + 2 O2-
(a1)
Anode:
Ca2+ + 2 e- → Ca
(b2)
(a2)
C + x O2- → COx + 2x e-
Ca-X
alloy
Cathode:
TiO2 + 4 e- → Ti + 2 O2-
(c1)
Anode:
Ca → Ca2+ + 2 e-
(c2)
Ca2+ + 2 e- → Ca
(c3)
Electrolysis
Anode:
C + x O2- → COx + 2x e-
TiO2 EMR CaCl2
MSE
feed
molten salt
(b3)
Fig. Schematic illustration of experimental apparatus
for titanium smelting in the future.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Cathode:
Anode:
C + x O2- → COx + 2x e- (c4)
Over all reaction
TiO2 + C → Ti + CO2
(d)
34
Features of several titanium production process
Kroll Process
◎
◎
○
○
○
FFC Process
◎
○
Advantages
High purity titanium available
Easy metal / salt separation
Established chlorine circulation
Utilizes efficient Mg electrolysis
Reduction and electrolysis operation
can be carried out independently
Simple process
Semi-continuous process
◎ Simple process
○ Semi-continuous process
PRP (Preform ◎ Effective control of purity
and morphology
Reduction
◎ Flexible scalability
Process)
◎ Resistant to contamination
○ Small amount of fluxes necessary
◎ Resistant to iron and carbon
EMR / MSE
contamination
Process
○ Semi-continuous process
○ Reduction and electrolysis operation
can be carried out independently
OS Process
Disadvantages
× Complicated process
× Slow production speed
× Batch type process
× Difficult metal / salt separation
× Reduction and electrolysis have to be
carried out simultaneously
△ Sensitive to carbon and iron contamination
△ Low current efficiency
× Difficult metal / salt separation
△ Sensitive to carbon and iron contamination
△ Low current efficiency
× Difficult recovery of reductant
× Environmental burden by leaching
× Difficult metal / salt separation when oxide
system
× Complicated cell structure
△ Complicated process
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
35
Product Ti pellets
Ti (+ CaO + CaCl2)
Carbon anode
Feed preform
(TiO2 + CaCl2)
Current monitor
/ controller
A
A
Vn
e-
CaCl2-CaO
e- Ca
V
e-
COx gas
e-
CaCl2-CaO molten salt
O2- , Ca2+
Ca-X reductant alloy
Ca (Ca-X alloy)
TiO2 + 4 e- = Ti + 2 O2-
C + x O2- = COx + 2x e-
Ca (Ca-X alloy) = Ca2+ + 2 e-
Ca2+ + 2 e- = Ca (Ca-X alloy)
Daytime reduction
Nighttime electrolysis
Fig. Conceptual image of
the new titanium reduction
process currently
under investigation
(EMR / MSE process,
Oxide system).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
36
Preform Reduction Process (PRP)
TIG weld
Stainless steel cover
Stainless steel
reaction vessel
MOx + R → M + RO
Feed preform
(MOｘ + flux)
Stainless steel plate
R reductant
M = Nb, Ta, Ti
R = Mg, Ca…
Ti sponge getter
Fig. Schematic illustration of the experimental apparatus for producing
titanium powder by means of the preform reduction process (PRP).
1. Amount of flux (molten salt) is small.
2. Easy to prevent contamination
from reaction vessel and reductant.
3. Highly scalable.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
37
(a) Conventional Metallothermic Reduction
(b) Preform Reduction Process (PRP)
Feed powder
Feed preform
Reductant vapor
Reductant vapor
Reductant (R = Ca, Mg)
Reductant (R = Ca, Mg)
Fig. Metal powder production process:
(a) conventional metallothermic reduction,
(b) preform reduction process (PRP).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
38
Selective chlorination using MgCl2
Vacuum pump
Glass flange
Glass beads
Chlorides
Condenser
Stainless steel net
Deposit
FeOx (s) + MgCl2 (l)
= FeClx (l) + MgO (s)
(FeClx．．．)
Stainless steel susceptor
Carbon crucible
Chlorination
Reactor
Mixture of
Ti ore
and MgCl2
RF coil
Quartz flange
Ceramic tube
N2 or N2+H2O gas
(Fe-free Ti ore)
Experimental condition
T = 1100 K, t’ = 1 h,
Atmosphere : N2,
Ti ore (UGI) : 4 g, MgCl2 : 2 g
Fig. Experimental apparatus for selective-chlorination of titanium ore using MgCl2 as a chlorine source.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
39
Results of previous study
FeOx (s) + MgCl2 (l) = FeClx (l, g) + MgO (s)
XRD analysis
XRF analysis
Intensity, I (a. u.)
Deposit obtained after selective
-chlorination. → FeCl2 was generated.
: FeCl2
Residue after selective-chlorination.
→ Fe was selective chlorinated.
Table Analytical results of titanium ore,
the residue after selective chlorination,
and the sample after reduction.
These values are determined by XRF analysis.
Concentration of element i, Ci (mass %)
Ti
Fe
Si
Al
V
10 20 30 40 50 60 70 80 90 100 Ti ore (UGI from Ind.) 95.10 2.29
0.41 0.12 0.75
96.45
0.43
0.44 0.37 1.50
After reduction sample 98.30
0.05
0.38 0.12 0.52
Angle, 2θ (deg.)
Fig. XRD pattern of the deposit
at chlorides condenser.
The sample powder was sealed
in Kapton film before analysis.
After heating sample
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
40
Chlorination of Ti using FeCl2
Quartz tube
Sample mixture:
(e.g., FeCl2+Ti powder)
Ti (s) + 2 FeCl2 (s)
= TiCl4 (g) + 2 Fe (s)
Sample deposits
Heater Carbon crucible
(on Si rubber, NaOH gas trap and quartz tube)
Fig. Experimental apparatus for chlorination of titanium using FeCl2 as a chlorine source.
XRF analysis
Table Analytical results of the samples before and after heating and the sample
deposited on quartz tube and Si rubber. These values are determined by XRF analysis.
Concentration of element i, Ci (mass %)
Residue before heating
Residue after heating
Dep. on quartz tube after heating
Dep. on Si rubber after heating
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Ti
18.4
Fe
45.3
Cl
36.2
9.8
3.5
80.1
50.4
9.0
46.1
64.9
0.9
34.1
41
This study
Low-grade Ti ore MClx
(FeTiOx)
(CaCl2)
Selective chlorination
by electrochemical method
Upgraded Ti ore FeClx
(TiO2)
FeClx Ti scrap
Chlorine recovery
Fe
TiCl4
(+ AlCl3)
Ti smelting
by electrochemical method
Ti metal
Fig. Flowchart of new titanium smelting process
from titanium ore discussed in this study.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
42
Iron removal process by electrochemical method
Selective chlorination・Iron removal process
Cathode： Fen+ + n e- → Fe
Ca2+ + 2 e- → Ca
Anode ：
e-
2. TiO2 reduction process
(e.g. EMR-MSE process)
Cathode： TiO2 + 4 e- → Ti + O2-
2 Cl- → Cl2 + 2 eFeOx + Cl2 → FeClｘ(l, g) + O
Anode ： Ca（or Ca-X） → Ca2+ + 2 e-
A
V
Ti ore（TiO2 + FeOｘ）
A
e-
e-
Reference electrode
e-
Mild steel crucible（Cathode）
TiFeOX
O2-
Carbon electrode
TiO2 Ti
Ti crucible（Cathode）
Molten CaCl2
Molten CaCl2-CaO
Carbon crucible(Anode)
Ca-X alloy
Ti reduction
Production of reductant
Establishment of a new up-grading process
of Ti ore by electrochemical method.
Direct reduction process from Ti ore to Ti metal can be achieved.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
43
(a) Iron removal process
(b) FFC process (Fray et al., 2000)
e-
Carbon crucible containing
Ti ore + CaCl2 mixture (Anode)
e-
Carbon anode
CaCl2
molten salt
Molten CaCl2
Sample
Mild steel crucible (Cathode)
Electrolysis
Cathode: Ca2+ + 2 eAnode:
2 Cl-
TiO2 preform
Electrolysis
→ Ca
(a1)
Cathode: TiO2 + 4 e- → Ti + 2 O2-
→ Cl2 + 2 e-
(a2)
Anode:
FeOx + Cl2 + C → FeClx + COx
C + x O2- → COx + 2x e-
(b1)
(b2)
(a3)
Fig. Schematic illustrations of the processes
investigated in this study.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
44
Potential of several reaction
@1100 K
2CaCl2 + O2 → 2CaO ＋ 2Cl2
log pCl22 / pO2 = -8.29
2MgCl2 + O2 → 2MgO ＋ 2Cl2
log pCl22 / pO2 = 0.48
4HCl + O2 → 2H2O ＋ 2Cl2
log pCl22 / pO2 = 1.49
2CO + O2 → 2CO2
log pO2 = -17.74
2C + O2 → 2CO
log pO2 = -19.85
e.g.
FeO + MgCl2 → FeCl2 + MgO
ΔG = -0.28 kJ < 0
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
45
Table Gibbs energy change of formation in the Fe-Ti-O system.
Reactions
Fe (s ) + Cl2 (g ) = FeCl2 (s )
Fe (s ) + Cl2 (g ) = FeCl2 (l )
Fe (s ) + 1.5 Cl2 (g ) = FeCl2 (g )
Fe (s ) + 1.5 Cl2 (g ) = FeCl3 (g )
Fe (s ) + 0.5 O2 (g ) = FeO (s )
2 Fe (s ) + 1.5 O2 (g ) = Fe2O3 (s )
3 Fe (s ) + 2 O2 (g ) = Fe3O4 (s )
Ti (s ) + Cl2 (g ) = TiCl2 (s )
Ti (s ) + Cl2 (g ) = TiCl2 (g )
Ti (s ) + 1.5 Cl2 (g ) = TiCl3 (s )
Ti (s ) + 1.5 Cl2 (g ) = TiCl3 (g )
Ti (s ) + 2 Cl2 (g ) = TiCl4 (g )
Ti (s ) + 0.5 O2 (g ) = TiO (s )
Ti (s ) + 0.5 O2 (g ) = TiO (g )
Ti (s ) + O2 (g ) = TiO2 (s )
2 Ti (s ) + 1.5 O2 (g ) = Ti2O3 (s )
3 Ti (s ) + 2.5 O2 (g ) = Ti3O5 (s )
4 Ti (s ) + 3.5 O2 (g ) = Ti4O7 (s )
Gibbs energy change, ΔG
900 K
1100 K
-228.93
-212.65
-183.14
-190.89
-236.41
-231.45
-213.15
-200.71
-585.32
-535.98
-821.79
-762.36
-370.38
-340.24
-258.15
262.11
-526.31
-485.79
-495.25
-485.30
-654.50
-630.68
-455.54
-437.16
-32.67
-50.63
-780.23
-744.91
-1267.35
-1215.50
-2052.96
-1969.32
-2838.53
-2718.92

f
(kJ/mol) Ref.a
1300 K
[1]
[1]
-194.39 [1]
-225.62 [1]
-188.00 [1]
-486.33 [1]
-702.25 [1]
-310.26 [1]
-265.30 [1]
[1]
-474.73 [1]
-606.36 [1]
-418.80 [1]
-67.66 [1]
-709.30 [1]
-1163.77 [1]
-1885.27 [1]
-2599.03 [1]
a: References
[1] I. Barin, Thermochemical Data of Pure Substances, 3rd ed., (Weinheim, Federal Republic of Germany,
VCH Verlagsgesellschaft mbH, 1997).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
46
Temperature, T / K
2000
0
1000
500
400
Vapor pressure, log pi (atm)
-2
Region suitable
for vaporization
of chlorides
-4
-6
-8
-10
Fig. Vapor pressure of iron, calcium,
magnesium and titanium chlorides
-12
as a function of reciprocal temperature.
0.5
1.0
1.5
2.0
2.5
Reciprocal temperature, 1000 T-1 / K-1
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
47
Thermodynamic analysis (FeOx chlorination)
Fe-Cl-O system, T = 1100 K
Oxygen partial pressure, log pO2 (atm)
0
CaO (s) / CaCl2 (l)
aCaO = 0.1
Fe2O3 (s)
-10
-20
Fe3O4 (s)
H2O (g) / HCl (g)
Ti ore :
mixture of TiOx and FeOx.
CO / CO2 eq.
C / CO eq.
FeO (s)
MgO (g) / MgCl2 (l) eq.
-30
FeCl2 (l)
FeOX (s) + MgCl2 (l)
-40
Fe (s)
FeCl3 (g)
e.g.
-50
-60
-40
-30
-20
-10
→ FeClX (l, g)↑ + MgO (s, l)
0
FeOx can be chlorinated
by controlling oxygen
and chlorine partial pressure.
Chlorine partial pressure, log pCl2 (atm)
Fig. Chemical potential diagram for Fe-Cl-O system at 1100 K.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
48
Thermodynamic analysis (TiOx chlorination)
Ti-Cl-O system, T = 1100 K
Fe / FeCl2 eq.
CaO (s) / CaCl2 (l)
aCaO = 0.1
Oxygen partial pressure, log pO2 (atm)
0
-10
TiO2 (s)
H2O (g) / HCl (g)
Ti ore :
mixture of TiOx and FeOx.
CO / CO2 eq.
C / CO eq.
-20
Ti3O5 (s) Ti4O7 (s)
Ti2O3 (s)
-30
MgO (g) / MgCl2 (l) eq.
TiO (s)
-40
TiCl3 (s)
-50
-60
-40
Ti (s)
TiCl2 (s) TiCl4 (g)
-30
-20
-10
0
Since TiCl4 is
highly volatile species,
chlorine partial pressure
must be kept
in the oxide stable region.
Chlorine partial pressure, log pCl2 (atm)
Fig. Chemical potential diagram for Ti-Cl-O system at 1100 K.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
49
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
50
This chapter
Low-grade Ti ore MClx
(FeTiOx)
(CaCl2)
Selective chlorination
by electrochemical method
Upgraded Ti ore FeClx
(TiO2)
FeClx Ti scrap
Chlorine recovery
Fe
TiCl4
(+ AlCl3)
Ti smelting
by electrochemical method
Ti metal
Fig. Flowchart of the new titanium smelting process
discussed in this study.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
51
Ti ore
Flux
Binder
Mixing
Flux :
CaCl2, MgCl2
Binder:
Collodion
Slurry
Preform fabrication
Feed preform
Calcination / Iron removal
FeClx
Sintered feed preform
Fig. Flowchart of the procedure of preform fablication
supplied for Fe removal experiment.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
52
Table Composition of titanium ore (ilmenite)
and up-graded ilmenite (UGI) used this study.
Sample name
Composition (mass%)
TiO2
ilmenaiteb
d
UGI
UGIe
Total Fe
Fe2O3 FeO
52.55 20.91 15.27
1.22
95.20
96.46 1.60
-
MnO Al2O3 SiO2
1.91c
0.99 0.77 0.63
0.03 0.28 0.52
a
MgO Nb2O5 P2O5 Moisture
0.21 0.11
0.61
0.61 0.27 < 0.01 0.10
0.03
0.15
a: Nominal value.
b: Natural ilmenite ore produced in Australia.
c: This is value as Mn.
d: Up-graded ilmenite by the Beacher process (see Fig. 1-7). The ore was produced in Australia.
e: Up-graded ilmenite by the Benilite process (see Fig. 1-6). The ore was produced in India.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
53
Table Starting materials used in this study.
Materials
Form
Purity or
conc. (%) Supplier
Collodiona
Liquid
5.0
Wako Pure Chemical., Inc.
CaCl2
Powder
95.0up
Kanto Chemicals, Inc.
Ca
Chip
98.0up
Ti
Sponge
98.0up
Osaka Tokusyu Goukin
Co., Ltd.
Toho Titanium Co., Ltd.
CH3COOH
Liquid
99.7
Kanto Chemicals, Inc.
HCl
Liquid
35
Kanto Chemicals, Inc.
2-Propanol
Liquid
99.5up
Kanto Chemicals, Inc.
Aceton
Liquid
99.0up
Kanto Chemicals, Inc.
Graphite
Crucible
99.98
Kanto Chemicals, Inc.
a:
5 mass% nitro cellulose, 23.75 mass% ethanol,
71.25 mass% diethylether.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
54
Experimental apparatus
Electrochemical interface
Sample
Voltage monitor
/ controller
e-
Furnace
Molten
CaCl2
10 A
power
source
Holes on
crucible
Mild steel crucible Graphite crucible
(Cathode)
containing Ti ore
(Anode)
Electrochemical
control unit
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
55
V1
V2
A1
A2
Potential lead (Nickel wire)
Stainless steel tube
Ar inlet
Rubber plug
Wheel flange
Reaction chamber
Thermocouple
Heater
Mild steel crucible
Graphite crucible
Ti ore, sample
Preform containing Ti ore
Molten salt (CaCl2)
Ceramic insulator
Fig. Schematic illustration of the experimental apparatus
in a voltage measurement.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
56
(a)
O.D. 19 mm
I.D. 17 mm
(b)
Support rod
(Stainless steel tube)
Air hole
Screw (Stainless steel)
Surface of molten salt
40 mm
Inlet of molten salt
Graphite crucible
Sample
(Ti ore, CaCl2 etc.)
Fig. Schematic illustration of the graphite crucible
used in this experiment, (a) appearance, (b) inner content.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
57
e-
A
i
CaCl2
molten salt
Immersion current,i / mA
8
6
TiO2 preform
(Cathode)
Carbon crucible
containing Ti ore (Anode)
4
2
0
-2
-4
0
500
1000
1500
Immersion time, t / s
2000
2500
Fig. Variation of the external current from the dipped preform
to the graphite crucible.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
58
V
CaCl2
molten salt
120
TiO2 preform
(Cathode)
Immersion voltage, V / mV
100
Carbon crucible
containing Ti ore (Anode)
80
60
40
20
0
-20
-40
0
500
1000
1500
2000
2500
Immersion time, t / s
Fig. Electromotive force between the dipped preform
and the graphite crucible.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
59
Table Analytical results of various samplesa.
Concentration of element i, Ci (mass%)b
Sample #
Ti
Fe
Ca
Cl
Si
Al
Cr
Fe / Ti ratioc,
RFe / Ti (%)
A
50.6 33.7
7.1
0.0
5.3
2.7
0.6
66.6
B
41.9
41.4
9.6
0.0
4.3
2.5
0.3
98.8
C
50.1
42.2
0.1
0.0
4.0
3.3
0.3
84.3
D
50.4
42.4
0.2
0.0
3.7
2.4
0.9
84.1
E
40.7
36.1 10.8
8.7
2.0
1.3
0.3
88.7
a:
Ilmenite (FeTiOx) produced in China.
b: Determined by X-ray fluorescence analysis.
This value excludes carbon and gaseous elements.
c: Indicator of iron removal from titanium ore.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
60
800
Temperature, T / ℃
782℃
Liquid
700
674℃
592℃
600
0
CaCl2
20
40
60
FeCl2 content, xFeCl2 (mol%)
80
100
FeCl2
Fig. Phase diagram for the CaCl2-FeCl2 system [2].
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
61
V2
V1
Potential lead (Nickel wire)
A
Stainless steel tube
Ar inlet
Rubber plug
Wheel flange
Reaction chamber
Thermocouple
Heater
Mild steel crucible (working)
Nickel quasi-reference electrode
Graphite crucible (counter)
Ti ore
Molten salt (CaCl2)
Ceramic insulator
Fig. Schematic illustration of the experimental apparatus
for cyclic voltammetry in molten CaCl2.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
62
2
(a)
1
Current, i / A
0
-1
2
(b)
Ca2+ + 2 e- = Ca (on Fe)
1
0
3.2 V
-1
2 Cl- = Cl2 + 2 e- (on C)
-2
-1
0
1
Potential (vs Ni quasi-ref.), E / V
2
Fig. Cyclic voltammograms for molten CaCl2 at 1100 K
(a) before pre-electrolysis, (b) after pre-electrolysis,
cathode sweep; working: Fe rod; counter: C rod,
anode sweep; working: C rod; counter: Fe rod,
scan rate: 100 mV / s, immersion length: 4 cm.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
63
Table Standard Gibbs energy of formation and
theoretical voltage for reactions in this study.
Reactions
Fe (s ) + Cl2 (g ) = FeCl2 (l )
Fe (s ) + 1.5 Cl2 (g ) = FeCl2 (g )
Fe (s ) + 1.5 Cl2 (g ) = FeCl3 (g )
Fe (s ) + 0.5 O2 (g ) = FeO (s )
2 Fe (s ) + 1.5 O2 (g ) = Fe2O3 (s )
3 Fe (s ) + 2 O2 (g ) = Fe3O4 (s )
Ti (s ) + 0.5 O2 (g ) = TiO (s )
Ti (s ) + 0.5 O2 (g ) = TiO (g )
Ti (s ) + O2 (g ) = TiO2 (s )
2 Ti (s ) + 1.5 O2 (g ) = Ti2O3 (s )
3 Ti (s ) + 2.5 O2 (g ) = Ti3O5 (s )
4 Ti (s ) + 3.5 O2 (g ) = Ti4O7 (s )
Ca (s ) + Cl2 (g ) = CaCl2 (l )
Ca (s ) + 0.5 O2 (g ) = CaO (s )
CaO (s ) + C (s ) = Ca (s ) + CO (g )
CaO (s ) + 0.5 C (s ) = Ca (s ) + 0.5 CO2
C (s ) + 0.5 O2 (g ) = CO (g )
C (s ) + O2 (g ) = CO2 (g )
Fe (s ) + Ti (s ) + 1.5 O2 (g ) = FeTiO3
2 Fe (s ) + Ti (s ) + 2 O2 (g ) = Fe2TiO4
Gibbs
energy
change,
ΔG f / kJ
-212.65
-190.89
-231.45
-200.71
-535.98
-762.36
-437.16
-50.63
-744.91
-1215.50
-1969.32
-2718.92
-629.11
-520.78
-312.00
-323.00
-209.06
-395.92
-956.61
-1164.70
Theoretical
voltage
Temperature,
Ref.a
for reactions, T / K
ΔE of / V
1.10
0.99
1.20
1.04
0.93
0.99
2.27
0.26
1.93
2.10
2.04
2.01
3.26
2.70
1.62
1.67
1.08
1.03
1.65
1.51
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
1100
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
[1]
a: References
b: DE o = -DG o / nF, where n is electron transfer number, and F is Faraday constant.
[1] I. Barin, Thermochemical Data of Pure Substances, 3rd ed., (Weinheim,
Federal Republic of Germany, VCH Verlagsgesellschaft mbH, 1997).
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
64
(a)
2
Ca2+ + 2 e- = Ca (on Fe)
1
0
3.0 V
-1
2 Cl- = Cl2 + 2 e- (on C)
(b)
Current, i / A
2
Ca2+ + 2 e- = Ca (on Fe)
1
0
1.7 V
-1
C + x O2- = COx + 2x e- (on C)
(c)
2
Ca2+ + 2 e- = Ca (on Fe)
1
0
1.7 V
-1
C + x O2- = COx + 2x e- (on C)
-2
-1
0
1
2
Potential (vs Ca / Ca2+ ref.), E / V
3
Fig. Cyclic voltammograms for molten CaCl2
at 1100 K after Ca deposition
using various carbon electrode,
(a) C rod, scan rate: 100 mV / s,
(b) C crucible, scan rate: 100 mV / s,
(c) Ti ore holding C crucible,
scan rate: 20 mV / s,
cathode sweep; working: Fe rod; counter: Carbon,
anode sweep; working: Carbon; counter: Fe rod,
immersion length: 2 cm.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
65
120
0
Temperature, T’ / ˚C
1100
Liq.
Two liquids
1000
900
825˚
800
828˚
767˚
700
0
CaCl2
20
40
60
80
Ca content, xCa (mol%)
100
Ca
Fig. Phase diagram for the CaCl2–Ca system [3].
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
66
e-
Mild steel crucible
(Cathode)
Carbon crucible containing
Ti ore + CaCl2 mixture
(Anode)
Sample
Molten CaCl2
Fig. Schematic illustration of experimental apparatus
for iron removal by electrochemical method.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
67
V
Potential lead (Nickel wire)
A
Stainless steel tube
Ar inlet
Rubber plug
Wheel flange
Stainless steel reaction chamber
Thermocouple
Heating element
Mild steel crucible (Cathode)
Graphite crucible (Anode)
Ti ore
Molten salt (CaCl2)
Ceramic insulator
Fig. Schematic illustration of the experimental apparatus
for iron removal by electrochemical method.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
68
Ti ore ( + Fe2O3 etc)
CaCl2
Electrochemical iron removal
TiO2 + CaCl2
Distilled water
CH3COOH aq.,
HCl aq.,
Distilled water,
Isopropanol,
Acetone
CaCl2
Separation
TiO2
Leaching
S
L
Waste
solution
Vacuum drying
TiO2 powder
Fig. Flowchart of the procedure for iron removal experiment
by electrochemical method.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
69
Experiment 1
Experimental condition：
Temperature: 1100 K
Atmosphere: Ar
Molten salt: CaCl2 (800 g)
Cathode:
Mild steel crucible (I.D 96 mm)
Anode:
Graphite crucible (I.D 17 mm)
Mass of Ti ore
Exp. No. (Ilmenite), w / g
A
B
C
4.00
4.00
4.00
Sample
Voltage monitor
/ controller
e-
Voltage,
E/V
Time,
t’ / h
2.5
2.0
1.5
6
3
12
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Molten
CaCl2
Mild steel
crucible
(Cathode)
Graphite crucible
containing Ti ore
(Anode)
70
Result 1
Disscussion
XRF analysis
Table Analytical results of the sample obtained
after the electrochemical selective chlorination.
Sample
Concentration of element i,
Ci (mass %)
Ti
Ti ore
Exp. A
Exp. B
Exp. C
42.6
64.2
55.4
45.7
Fe
Ca
48.7 2.2
29.6 0.5
25.3 13.8
21.7 12.3
Si
2.2
1.8
1.1
1.4
Ti ore (Ilmenite, FeTiOx)
Fe / Ti
ratio,
e-
V RFe / Ti (%)
0.6
0.9
1.2
2.7
114
49.5
45.6
47.4
a: Average of the samples obtained from
the upper part and lower part of the graphite crucible.
Molten CaCl2
Unreacted part
After the electrochemical treatment,
Fe in the Ti ore was selectively
chlorinated and removed.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Graphite crucible
(Anode)
Unreacted part was
remained at the bottom
of the graphite crucible.
71
Table Experimental condition for iron removal from Ti ore by electrochemical methodc.
Exp.
Mass of feed
materials i, wi / g
UGIa
Voltage,
V / volts
Reaction
time,
t / hr
Exp.
Ilmeniteb
Mass of feed
materials i, wi / g
UGIa
Voltage,
V / volts
Reaction
time,
t / hr
Ilmeniteb
A
2.76
2.0
1.0
I
4.00
2.5
3.0
B
2.82
1.2
1.0
J
4.03
1.5
3.0
C
2.92
1.0
1.0
K
4.01
1.5
6.0
D
2.91
0.5
1.0
L
3.99
1.0
6.0
E
2.88
2.0
3.0
M
4.00
0.5
6.0
F
2.81
1.0
6.0
N
3.93
ー
6.0
G
2.75
0.5
0.5
O
4.01
1.5
9.0
H
1.42
1.2
1.0
P
4.00
2.0
13.0
a: Upgrade ilmenite by the Benilite process (see Fig.1-6 ).
The ore was produced in India (see Table 3-1).
b: Ilmenite (FeTiOx) produced in China.
c: Temperature: 1100 K, Ar atmosphere.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
72
10 A
Power
Source
20 cm
Fig. Schematic illustration of electrochemical interface in this experiment.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
73
2.0
Current, I / A
1.5
Exp. K
1.0
Exp. L
0.5
Exp. M
0
Exp. N
-0.5
0
10000
20000
Time, t / second
Fig. Current generated by imposed each voltage.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
74
Table Analytical results of the samples obtained after iron removal by electrochemical method.
a
Exp.
Composition i , C i / mass %
#
Al
Si
S
Cl
Ca
Sc
Ti
V
UGIc
0.0 0.1 nd 0.0
0.1 nd 96.3 0.2
c
0.4 1.1 0.5 nd
0.1 0.4 92.8 1.2
UGI
A
0.2 0.4 0.0 nd 38.8 0.2 55.4 1.1
B
nd
nd
nd
nd
nd
nd
nd
nd
C
0.3 1.1 0.1 nd 15.3 0.1 80.2 1.4
D
0.2 0.9 0.0 nd
5.3 0.3 90.1 1.0
E
0.2 0.4 0.0 0.0 45.7 0.2 49.8 1.5
F
0.2 0.8 0.0 nd 30.4 0.1 66.4 1.1
G
nd
0.1 0.1 nd 11.3 0.1 86.5 1.5
H
0.1 0.2 0.0 nd 21.4 0.1 76.4 1.1
d
1.8 1.8 0.0 nd
0.2 0.2 44.8 0.7
Ilmenite
d
2.6 2.6 0.0 nd
0.5 0.2 40.4 0.6
Ilmenite
d
0.8 2.0 0.0 nd
0.2 0.3 45.7 0.5
Ilmenite
d
1.0 1.4 nd
nd
0.2 0.4 45.0 0.5
Ilmenite
I
1.1 0.5 0.0 0.1 9.0 0.3 53.8 0.9
J
0.9 1.5 0.1 nd
6.4 0.2 56.0 0.7
K
1.0 6.2 0.1 nd
8.1 0.1 58.1 1.1
L
1.3 4.5 0.1 nd 21.5 0.1 56.7 1.2
M
1.2 2.8 0.1 0.4 20.2 nd 46.7 0.8
N
1.2 1.9 0.0 1.7 35.4 0.1 37.7 0.7
O
0.1 0.2 0.0 0.2 35.3 0.3 49.1 1.0
P
0.1 0.5 0.0 0.1 28.5 0.2 41.4 0.8
Q
0.6 0.6 0.0 0.2 33.4 0.2 52.2 1.2
a: Determined by XRF analysis.
b: Experimental date.
c: Upgraded ilmenite produced in Australia.
d: Ilmenite (FeTiOx) produced in China.
nd: not detected. Below detection limit of XRF (< 0.01%)
Mn
1.0
1.3
0.4
nd
0.3
0.9
0.6
0.4
0.2
0.2
3.3
2.9
3.2
3.0
0.9
0.7
0.9
0.8
1.6
0.6
1.0
1.5
0.7
Fe
1.9
2.3
2.6
nd
1.3
1.3
1.6
0.6
0.2
0.4
47.2
50.2
47.2
48.5
33.3
33.5
24.0
12.8
26.1
20.5
12.8
26.7
10.8
Ni
0.0
0.0
0.8
nd
0.0
0.0
0.1
nd
nd
0.0
0.0
0.1
0.0
0.1
0.1
0.1
0.5
0.9
0.1
0.0
nd
nd
nd
Fe / Ti
/%
2.00
2.45
4.65
nd
1.63
1.40
3.27
0.98
0.24
0.56
105.3
124.4
103.2
107.9
61.9
59.9
41.3
22.6
55.8
54.6
26.0
64.6
20.7
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
Note
b
051227-UGIAUS
050125_UGI
050125_UGI_P04_1
050119_UGI_P02
050125_UGI_P05_2
050125_UGI_P06_1
050125_UGI_P07_2
050127_UGI_P10_1
050119_UGI_P01_1
050119_UGI_P03_1b
050420_ilmenite
050420_ilmenite
050615_ilmenite
050607_ilmenite
050425_ilmenite_P33_2
050428_ilmenite_P38_1
050217_ilmenite_P15_1
050217_ilmenite_P14_1
050216_ilmenite_P13_3
050216_ilmenite_P12_2
050517_ilmenite_P46_2
050516_ilmenite_P45_1
050502_ilmenite_B_1
75
100 mm
V1
V2
A1
A2
Potential lead (Ni wire)
Stainless steel tube
(Electrode)
Ar inlet
Rubber plug
Wheel flange
Thermocouple
Heater
Mild steel crucible (Cathode)
Graphite crucible (Anode)
Ti ore + CaCl2 mixture
Molten salt (CaCl2)
Ceramic insulator
Fig. Schematic illustration of experimental apparatus in this experiment.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
76
3
Current
Current / A
10
Voltage
8
2.5
2
6
1.5
4
1
2
0.5
0
0
3000
6000
Time / s
9000
Voltage / V
12
0
12000
Fig. Current value passed by imposed certain voltage,
and voltage in this experiment, Exp. F.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
77
Intensity, I (a. u.)
: CaTiO3
(JCPDS #42-0423)
: TiO2
(JCPDS #21-1276)
10
20
30
40
50
60
70
80
90
100
Angle, 2θ (degree)
Fig. XRD pattern of the obtained sample
after selective chlorination experiment.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
78
Table Experimental condition and analytical results of the chlorination experiment using ilmenite.
Obtained
Mass of feed material i , w i / g CaCl2 / FeOx Imposed Reaction Average Fe / Ti
ratio,
voltage,
time,
current,
sample,
ratioa,
Exp. Ilmemite Carbon CaCl2
Noteb
M Ca / Ti / V / volts.
t / hr
I / A R Fe / Ti / %
w /g
c
Ilmenite
105.5
050420_ilmenite
A
1.25
1.80
2.0
1.5
3
2.52
54.8
0.85
050610_P48
1
B
1.87
1.33
1.0
1.8
6
1.72
74.8
1.26
050613_P49
C
1.47
1.60
1.5
1.8
8
2.83
19.3
0.52
050614_P50
2
D
0.75
2.19
4.0
2.0
3
1.59
96.2
0.63
050624_P53
E
0.79
2.00
3.7
2.0
6
5.09
050725_P55
F
0.87
2.35
3.7
5.91
7.2
0.97
050803_P56
c
c
G
3.99
2.0
3
3.60
54.9
2.60
050811_P57
3
H
0.77
2.18
4.0
1.5
3
5.87
57.4
0.48
050811_P58
(Old)
I
0.77
0.18
2.14
4.0
1.5
3
3.09
24.7
0.03
050814_P59
J
0.74
2.12
4.0
1.5
3
4.49
48.8
0.76
050816_P60
K
0.74
2.17
4.0
1.5
3
5.00
3500
0.02
050816_P61
L
0.72
2.19
4.0
6
34.2
0.55
051014_P62
M
0.73
2.20
4.0
0.0
6
-0.004
48.7
0.55
051014_P63
N
0.62
2.26
5.0
1.5
3
0.68
46.2
0.37
051017_P64
O
0.61
2.25
5.0
1.5
6
0.42
37.7
0.41
051018_P66
P
0.74
1.5
3
0.47
72.7
0.56
051019_P67
Q
0.73
0.16
2.00
3.7
2.5
6
1.95
051020_P69
4
R
0.74
2.17
4.0
2.5
6
1.81
12.4
0.42
051021_P70
S
0.60
2.26
5.0
1.5
3
1.27
107.0
0.31
051025_P72
T
0.60
2.21
5.0
2.0
6
0.79
126.8
0.59
051025_P73
U
0.60
2.21
5.0
d
d
4.10
354.4
0.02
051026_P74
V
0.67
2.37
5.0
e
e
12.9
0.38
051114_P75
a: Indicator of iron removal from titanium ore.
b: Experiment number
c: Ilmenite (FeTiOx) produced in China.
d: 2.0 volts 20 minutes, and 1.5 volts 3hours
e: 1.8 volts 6 hours, and 3.0 volts 3 hours
f: 2.0 volts, 1.5 volts, 1.8 volts, and 2.0 volts, 1 hour respectively
Use
bath #
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
79
Table Experimental conditions and analytical results of the chlorination experiment using UGI.
Use Mass of feed material i , w i / g CaCl2 / FeOx Imposed Reaction Fe / Ti Obtained Mass decrease of
b
sample, carbon crucible,
bath
ratio,
voltage,
time,
ratio ,
a
c
CaCl2
Exp.
UGI
Note
w2 / g
#
M Ca / Ti / V / volts t / hour R Fe / Ti / % w 1 / g
051227_UGIAUS
2.00d
A
1.55
1.27
20
2.0
3
051219_P77
A
1.59
1.26
20
2.0
3
0.28
0.09
0.13
051222_P89
B
2.08
0.84
10
2.0
3
051219_P79
B
2.07
0.83
10
2.0
3
4.70
0.15
0.20
051221_P87
C
2.46
0.49
5
2.0
3
051220_P82
C
2.46
0.49
5
2.0
3
7.41
0.42
0.25
051221_P86
5
D
1.59
1.27
20
1.5
3
0.18
0.49
0.35
051220_P81
E
2.11
0.85
10
1.5
3
0.59
0.55
0.14
051219_P78
F
2.45
0.48
5
1.5
3
051220_P84
F
2.45
0.48
5
1.5
3
0.83
1.11
0.29
051221_P85
G
2.12
0.58
7
1.5
9.5
0.33
0.76
0.16
051220_P80
e
H
0.83
10
1.5
10
051222_P88
2.08
4
I
1.57
1.28
20
f
f
2.20
0.02
0.42
051115_P76
J
1.59
1.24
20
0.0
3
2.63
1.95
0.05
051220_P83
5
g
K
1.27
20
2.0
6
0.43
0.31
0.15
051222_P90
1.59
a: Up-graded ilmenite by the Beacher process (see Fig. 1-6). The ore was produced in Australia.
b: Indicator of iron removal from titanium ore.
c: Experiment date and number
d: Reference
e: Mixture 2.08 g of Ti ore and 0.08 g of carbon powder
f: 2 volts 2 hours, and 2 volts 2hours
g: Up-graded ilmenite by the Benilite process (see Fig. 1-5). The ore was produced in India.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
80
Low-grade Ti ore MClx
(FeTiOx)
(CaCl2)
Selective chlorination
by electrochemical method
Upgraded Ti ore FeClx
(TiO2)
FeClx Ti scrap
Chlorine recovery
Fe
TiCl4
(+ AlCl3)
Ti smelting
by electrochemical method
Ti metal
This chapter
Fig. Flowchart of new titanium smelting process
from titanium ore discussed in this chapter.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
81
V
A
Potential lead (Nickel wire)
Stainless steel tube
Ar inlet
Rubber plug
Wheel flange
Reaction chamber
Thermocouple
Heater
Mild steel crucible
Ti crucible (Cathode)
Graphite rod (Anode)
Mixture of Ti ore
after Fe removal and CaCl2
Molten salt (CaCl2)
Ceramic insulator
Fig. Schematic illustration of the experimental apparatus
for electrochemical reduction of Ti ore after Fe removal.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
82
Ti ore (+Fe2O3 etc)
CaCl2
Mixing
Mixture
CaCl2
CH3COOH aq.,
HCl aq.,
Distilled water,
Isopropanol,
Acetone
Electrochemical reduction
Ti + CaCl2
Leaching
S
L
Waste solution
Vacuum drying
Ti powder
Fig. Flowchart of the experimental procedure for
electrochemical reduction of Ti ore after Fe removal.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
83
Table Experimental conditions for electrochemical
reduction of Ti ore after Fe removal.
Exp. No.
Mass of feed material i, Ci / g
Voltage, Time,
E/V
t” / h
Ti ore
CaTiO3
CaCl2
R1
ー
1.50
2.50
1.5
3
R2
ー
1.50
2.50
3.0
3
R3
0.79a
ー
2.50
3.0
3
R4
0.76b
ー
2.50
3.0
3
a: The sample obtained by selective chlorination exp. A.
b: The sample obtained by selective chlorination exp. D.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
84
1000
Temperature, T’ / ˚C
950
900
1150 K
85
0
800
75
0
700
0
CaCl2
10
20
30
CaO content, xCaO (mol%)
CaO
Fig. Phase diagram for the CaCl2–CaO system.
2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006
85