1 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Iron Removal from Titanium Ore by Electrochemical Method Isao Obana 1 and Toru H. Okabe

1

Iron Removal from Titanium Oreby 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

2

AircraftSpacecraftChemical plantsImplantsArtificial bones, etc.

Applications

Lightweight and high strengthCorrosion resistantBiocompatibleSome titanium alloys ： shape memory effect superelasticity

Introduction

Ti ore + C + 2 Cl2 → TiCl4 (+ FeClx) + CO2

Chlorination

TiCl4 + 2 MgReduction

MgCl2

Electrolysis

The Kroll process: Currently employed Ti production processMg & TiCl4 Feed port

SpongeTitanium

→ Ti + 2 MgCl2

→ Mg + Cl2

ReactionContainer

MgCl2

Features of titanium

3

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.

Upgrading Ti ore

(CaCl2)

Ti ore (Ilmenite, FeTiOx) Upgraded Ilmenite (UGI)

TiOx

FeOx Others

TiOxFeOx

Others Upgrade Chloridewastes

Discarded

Ti metal

Ti smelting

Low grade Ti ore

Upgraded Ti ore FeClx(+AlCl3)

(FeTiOX)

(TiO2)

MClx

Chlorine recovery

Selective chlorination

Fe TiCl4

Ti scrap

Advantages:1．　Material cost can be

reduced by using low-grade ore.

4

Previous study

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).

The selective chlorination of Ti ore by MgCl2 or CaCl2 is found to be feasible.

Pyrometallurgical de-Fe process

FeOx (s, in Ti ore) + MgCl2 (s, l) → FeClx (l, g) + MgO (s)

CaCl2 (s, l) + H2O (g) → HCl (g) + CaO (s)

FeOx (s, in Ti ore) + HCl (g) → FeClx (l, g) + H2O (g)Susceptor

RF coil

Vacuum pump

Quartz Tube

Deposit

Mixture ofTi oreand MClx

N2 or N2+H2O gas

Condenser

(FeClx)

T = 973~1373 K

5

Study objectives

1. Thermodynamic analysis of selective chlorination2. Fundamental experiments of selective chlorination by electrochemical methods 3. Reduction experiment for the sample obtained by selective chlorination

Application of electrochemical methodusing molten salt

Low-grade Ti ore

TiO2 + flux

(FeTiOx)

Fe removal byselective chlorination

Ti powder

Direct reduction of TiO2

obtained after Fe removal

6

Fig. Chemical potential diagram for Fe-Cl-O and Ti-Cl-O systems at 1100 K

The selective chlorination of Ti ore by controlling chlorine partial pressuremay be possible using an electrochemical technique.

Thermodynamic analysis (Ti ore chlorination)

Ti ore : FeTixOy

For simplicity, it is assumed to be amixture of TiOx and FeOx

TiCl4 (g)

TiCl3 (s)

–40

–10

–30

–20

–50

–60

0

-40 -10-30 -20 0

CaO (s)/CaCl2 (l) eq.aCaO = 0.1

Fe-Cl-O and Ti-Cl-O system, T = 1100 K

Potential regionfor selective chlorinationof iron from titanium ore

Potential region for chlorinationof titanium

Oxy

gen

part

ial p

ress

ure,

lo

g p

O2 (

atm

)

Chlorine partial pressure, log pCl2 (atm)

C/CO eq.CO/CO2 eq.

H2O (g)/HCl (g) eq.

MgO (g)/MgCl2 (l) eq.

TiCl2 (s)

FeO (s)

Fe2O3 (s)

FeCl2 (l)

Fe3O4 (s)

FeCl3 (g)Fe (s)

TiO (s)

TiO2 (s)

Ti (s)

TiO2 →　 Stable

FeOx →　 FeClx (g)

7

2 Cl– (in CaCl2) → Cl2 + 2 e–

Anode:

Chlorine chemical potential in molten CaCl2 at anode

can be increased electrochemically.

Cathode ：

Ca2+ + 2 e– → Ca

Electrolysis

Fen+ + n e– → Fe

FeOx + Cl2 → FeClx↑ + O2–

e–

Molten salt (CaCl2, MgCl2, etc.)

DC power source

Upgraded orlow-grade Ti ore(e.g., FeTiOx)

FeCl3, AlCl3, O2, CO2 gas

Chlorination by increasing Cl2 potential

8

Reactions

CaCl2 (l) = Ca (l) + Cl2 (g) 629 3.26

FeO (s) = Fe (s) + 1/2 O2 (g) 201 1.04

FeO (s) + 1/2 C (s) = Fe (s) + 1/2 CO2 (g) 3 0.02

FeTiO3 (s) + CaCl2 (l) + 1/2 C (s)= TiO2 (s) + FeCl2 (l) + Ca (l) + 1/2 CO2 (g)

438 2.34

a: I. Barin: Thermochemical Data of Pure Substances, 3rd ed. (Weinheim, Federal Republic of Germany, VCH Verlagsgesellschaft mbH, 1997)

FeO (s) + CaCl2 (l) + C (s) = FeCl2 (l) + CO (g) + Ca (l) 409 2.23

Theoretical decomposition voltage

Under a certain condition, the selective chlorination of Fe in Ti ore may proceed below the theoretical decomposition voltage of CaCl2.

Go /kJ mol-1a E o /Va

Table Standard Gibbs energy of decomposition and theoretical voltage of that in several chemical species at 1100 K.

9

Iron removal by selective chlorination using an electrochemical method

Low-grade Ti ore

TiO2 + flux

(FeTiOx)


Ti powder



10

Experimental apparatus

(a) Reaction chamber (b) Reaction cell

Ceramic insulator

Thermocouple

Heater

Rubber plug

Ar inlet

Wheel flange

Stainless steel tube (Electrode)

Molten salt (CaCl2)

Potential lead (Nickel wire)

Mild steel crucible (Cathode)

Graphite crucible (Anode)

Sample

V

A

Height 40 mm

(a) (b)

I.D. 17 mm

O.D. 19 mm

Surface of molten salt

Support rod(Stainless steel tube)

Sample(Ti ore, CaCl2, etc.)

Screw (Stainless steel)

Graphite crucible

Air hole

Holes formolten salt diffusion

11

Selective chlorination experiments

Mass of sample i, wi/g

Ti oreCaCl2

Carbonpowder

4.00 ーーA

B

C

0.74

0.74

2.17

2.17

ー0.18

Voltage,E/V

Time,t”/h

1.5

1.5

1.5

12

3

3

Ilmenite UGI

D

E

1.59

1.59

1.27

1.27

ー 1.5

2.0

3

3

ー

ーー

ーーー

Experimental conditions：Temperature: Atmosphere: Molten salt: Cathode: Anode:

Exp. No.

Sample

MoltenCaCl2

Mild steelcrucible(Cathode)

Graphite cruciblecontaining Ti ore(Anode)

Voltage monitor/controller

e–

Low initial Fe content

1100 KArCaCl2 (800 g)Mild steel crucible (I.D. 96 mm)Graphite crucible (I.D. 17 mm)

12

Results of the selective chlorination experiments

XRF analysis

Fe/Ti ratio decreasedfrom 114% to 7.2% (ilmenite)and from 2.00% to 0.18% (UGI).

Table Analytical results of the samples obtained after electrochemical selective chlorination

0.295.9 1.9 0.1 0.1 2.00

94% of Fe in ilmenite and 92% of Fe in UGI were successfully removed.

Exp. D 0.598.0 0.2 0.1 0.3 0.18

Exp. E 0.296.9 0.3 0.2 0.5 0.28

UGI

0.642.6 48.7 0.3 2.2 114

Exp. A 2.745.7 21.7 12.3 1.4 47.4

Exp. B 0.447.2 3.4 47.9 0.0 7.2

Exp. C 0.130.2 7.5 42.7 0.3 24.7

Ilmenite

a: Average values of the samples obtained from the upper and lower parts of the graphite crucible

Concentration of elementi, Ci (mass%)

VTi Fe Ca Si

Fe/Tiratio,

RFe/Ti (%)

Sample

Exp. X 0.145.1 5.8 40.6 0.5 12.9

13

10 20 30 40 50 60 70 80 90 100

XRD analysis

A mixture of CaTiO3 and TiO2

was obtained after Fe removal.

Fig. XRD pattern of the start sample and the sample obtained after Fe removal (Exp. B)

:CaTiO3

:TiO2

Angle, 2θ (degree)

FeTiO3 (s) + CaCl2 (l)

→ CaTiO3 (s) + FeClx (l, g)

FeTiO3 (s) + CaCl2 (l) + C (s)

→ TiO2 (s) + FeClx (l, g) + COx (g) + Ca (s)

Discussion

CaTiO3 can be utilized as a feed material of direct TiO2 reduction processes(e.g., FFC, OS, EMR-MSE processes).

Inte

nsity

, I(a

. u.)

Ilmenite FeTiO3

Result of a selective chlorination experiment

14

Low-grade Ti ore

TiO2 + flux

(FeTiOx)


Ti powder



Direct reductionof TiO2 afterFe removal by electrochemicalmethod

15

Reduction experiment apparatus

Fig. Schematic illustration of the experimental apparatus in this study.

C + x O2– → COx + 2x e–

Anode:

Cathode:

TiO2 + 4 e– → Ti + 2 O2–

Electrolysis

CaCl2 molten salt

Ti crucible

Carbon anode

TiO2 feed

Direct reduction by electrochemical method was applied.

16

Reduction experiments

Mass of element i, wi / g

Ti ore CaCl2

2.50R-1

R-2

R-3 0.79

2.50

2.50

Voltage,E/V

Time,t”/h

1.5

3.0

3.0

3

3

3

CaTiO3

R-4 2.50 3.0 3

1.50

1.50

ー

0.76

Exp.

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)

ー

ー

ー

Table Analytical results of the sample obtained after electrochemical selective chlorination

0.295.9 1.9 0.1 0.1 2.00

Exp. D 0.598.0 0.2 0.1 0.3 0.18Exp. E 0.296.9 0.3 0.2 0.5 0.28

UGI

Concentration of element i,Ci (mass%)

VTi Ca SiFe

Fe/Tiratio,

RFe / Ti (%)

Sample

17

10 20 30 40 50 60 70 80 90 100

Result of the reduction experimentsXRD analysis

Fig. XRD pattern of the sample obtained after the reduction experiment (Exp. R-2)

Angle, 2θ (degree)

:Ti2O:CaTiO3

Inte

nsity

, I(a

. u.)

CaTiO3 was changed into Ti2O during this reduction experiment.

Fig. XRD pattern (Cu-K) of the obtained powder sample after reduction at 1173 K using the EMR process.

Inte

nsi

ty,

I (a

.u.)

9070503010

: Ti JCPDS # 44-1294

Angle, 2 (degree)

Ti reduction by EMR

In a previous study,low oxygentitanium powderwas obtained.

2500 ppm O

40 60 80 10020

A complete reduction was not achieved in this study.

e-

Carbon anode

TiO2 preform (Cathode)

e-

Current monitor

CaCl2 molten salt

Ca-X alloyRef. 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.

18

Summary

Ti powder

Reduction byelectrochemical method

Low-grade Ti ore

TiO2 + flux

(FeTiOx)

Iron removal byselective chlorination

Development ofan industrial scale process for producing low-cost titanium

・ 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.

19

Questionand

Answer

20

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.

21

024681012141618

1960 1970 1980 1990 2000

(a) Production of titanium sponge in the world (2003).

(b) Transition of production volume of titanium mill products in Japan.

Year

Am

ou

nt

of

tita

niu

m m

ill p

rod

uct

s [k

t]

17.4 kt (2004)

Fig. Current status of titanium production,

Total65.5 kt

USA8 kt

Japan18.5 kt (28% share)

Russia26 kt

Kazakhstan9 kt

China4 kt

(a) production of titanium sponge in the world (2003),(b) transition of production volume of titanium mill products in Japan.

Titanium Production

22

Melting point (K)Density (g / cc @298 K)

Specific strength((kgf / mm2) / (g / c

c))

Price (Yen / kg)

Titanium

Ti

19434.5

8 ~ 10

3000

~ 0.1

Aluminum

Al

933.32.7

3 ~ 6

600

20

Iron

Fe

18097.9

4 ~ 7

50

800

Symbol

Production volume(106 ton / year・ world)

Table Comparison between common metals and titanium.

Clarke numbera 0.46 (rank 10) 7.56 (rank 3) 4.7 (rank 4)

a: Values in parentheses are the existence rank in the earth’s crust.

23

Fig. Flowchart of the titanium production based on the Kroll process.

Ti feed (TiO2)

Chlorine (Cl2)

Sponge Ti

Ti ingot

MgCl2 + Mg

CO2, FeClx,AlCl3 etc.

Other compounds

MgCl2

Chlorination

Distillation

Reduction

Vacuum distillation

Crushing / Melting

Electrolysis

Crude TiCl4

Pure TiCl4

Sponge Ti + MgCl2 + Mg

H2S etc.

Reductant, Mg

Reductant (C)

Flowchart of the titanium production

24

(a) Low grade titanium ore (ilmenite) (b) Up-graded titanium ore (UGI)

Fig. (a) Composition of low grade titanium ore (ilmenite), and (b) that of up-graded titanium ore (up-graded ilmenite, UGI).

FeOx

2%

Others3%

TiOx

95%

TiOx

45%FeOx

45%

Others10%

Composition of titanium ore

25

Importance

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.

Ti ore (Ilmenite, FeTiOx) Upgraded Ilmenite (UGI)

TiOx

FeOx Others

TiOxFeOx

Others Upgrade Chloridewastes

Discarded

1. Reduction of disposal cost of chloride wastes2. Minimizing chlorine loss in the Kroll process3. Improvement of environmental burden4. Reduction of material cost using low grade ore

Upgrading Ti ore for minimizing chloride wastes

26

This study Advantages:1. Utilizing chloride wastes

from the Kroll process

2. Low cost Ti chlorination

3. Minimizing chlorine loss

in the Kroll process

caused by generation

of chloride wastes

Development of a new environmentally sound chloride metallurgy

Effective utilization of chloride wastes

Ti metal or TiO2 production

TiCl4 feed FeClx (+AlCl3)

Carbo-chlorination

COx

Low-grade Ti ore

Upgraded Ti ore FeClx(+AlCl3)

(FeTiOX)

(TiO2)

MClX

Chlorine recoverySelective chlorination(Cl2)

Fe

FeClx

TiCl4

Ti scrap

Refining process using FeClx

27

Reduction (in kiln)

Fe2+ / TiFe = 80~95%

145C° (2.5 kg/cm2) *4 hr*2 step

(90% purity)

Ilmenite Reductant (Heavy oil etc.)

Reduced ore HCl vapor

Leached ilmenite Water Spray acid Fuel

(Synthetic rutile)95% TiO2

1% TiFe

TiO2 HCl aq.

Leaching (in digestor)

Filtration Roasting

HClSol.TiO2 Iron oxide

Calcination Absorber

HCl aq.(18~20% HCl)

Fig. Flowsheet of the Benilite process.

The Benilite process

28

Gas + particle Particle

Ilmenite

Gas

Reduced ilmenite

TiO2

(Synthetic rutile) TiO2 92~93% TiFe 2.0~3.5%

TiO2

TiO2

Reduction (in kiln)

Leaching

WasteMag. separator

Acid Leaching

Filtering / Drying

Screen

-1 mm+1 mm

Cyclone

Reduced ore

Coal (low ash) Air

NH4Cl

H2SO4 aq.

Air

Iron oxide + Sol.

Iron oxide Sol.

Thickener

Fig. Flowchart of the Beacher process.

(Non. mag.)

The Beacher process (WLS)

29

Thermocouple

Ceramic tube

Fused CaCl2 bath

TiO2 powder

Cathode (stainless steel)

Alumina tube

Anode lead wire (W)

Alumina crucible

Graphite crucible (anode)

Electric furnace

TiO2 (CaCl2) + 4 e- → Ti + 2 O2- (CaCl2)

Fig. Electrochemical reduction of TiO2 in CaCl2. (Ref. Mem. Fac. Eng., Nagoya Univ., 19, (1967) 164-166.)

or TiO2 (CaCl2) + 2 Ca → Ti + 2 CaO

30

Fig. The principle of electrochemical deoxidization of titanium. (Ref. Met. Trans. B, 24B, June, (1993) 449-455.)

Cl2 COX

CaCl2 molten salt

O2-

[O] in Ti

Ti

C

e-

Ti

Ca[O] O2-

Carbon anode Ti cathode

e-

O2-

Ca2+ Cl-

Ca2+

Ca2+

Cl-

Cl-

Ca2+

O2-

Ca2+

Ca

CaO (in Ti) + 2 e- → O2- (in CaCl2)

31

TiO2 + 4 e- → Ti + 2 O2 (in CaCl2)

Fig. Schematic illustration of the procedure of the FFC process. (Ref. Nature, 407, 21, Sep. (2000) 361.)

Titanium ore

Chlorination orsulfate method

Titanium oxide

Mixing withBinder

Cathodeformation

Calcination

Titanium reduction by FFC process

Recovery oftitanium electrode

Crushingand leaching

FFC titanium

AnodeCathode

Molten saltTiO2

(TiO2 electrode)

TiO2 C

COx

32

FFC Process (Fray et al., 2000)

C + x O2- → COx + 2x e-

Anode:

Cathode:

TiO2 + 4 e- → Ti + 2 O2-

Electrolysis

(a1)

(a2)

OS Process (Ono & Suzuki, 2002)

C + x O2- → COx + 2x e-

Anode:

TiO2 + 2 Ca → Ti + 2 O2- + Ca2+

Cathode:

Ca2+ + 2 e- → Ca

Electrolysis(b1)

(b2)

(b3)

e-

CaCl2 molten salt

TiO2

preform

Carbon anode e-

TiO2 powder

CaCl2 molten salt

Carbon anode

Ca

Production process under investigation

33

EMR / MSE Process (Electronically Mediated Reaction / Molten Salt Electrolysis)

Production process under investigation

TiO2 + C → Ti + CO2

Over all reaction

(d)

Ca → Ca2+ + 2 e-

Anode:

Cathode:

TiO2 + 4 e- → Ti + 2 O2-

C + x O2- → COx + 2x e-

Ca2+ + 2 e- → Ca

Cathode:

Anode:

Electrolysis

(c4)

(c1)

(c2)

(c3)

(a) TiO2 reduction (b) Reductant production

e-

Carbon anode

TiO2

e-

Ca-X alloy (X = Ag, Ni, Cu,・・・)

e-e-

CaCl2 -CaO molten salt

Current monitor / controller

34

(a) FFC Process (Fray et al., 2000)

C + x O2- → COx + 2x e-

Anode:

Cathode:

TiO2 + 4 e- → Ti + 2 O2-

Electrolysis

(a1)

(a2)

(b) OS Process (Ono & Suzuki, 2002)

C + x O2- → COx + 2x e-

Anode:

TiO2 + 2 Ca → Ti + 2 O2- + Ca2+

Cathode:

Ca2+ + 2 e- → Ca

Electrolysis

(b1)

(b2)

(b3)

e-

CaCl2 molten salt

TiO2 preform

Carbonanode

e-

TiO2 powder

CaCl2 molten salt

Carbonanode

Ca

e- Carbon anode

CaCl2molten salt

TiO2 feed

e-


Ca-X alloy

e-

EMR MSE

Fig. Schematic illustration of experimental apparatus for titanium smelting in the future.

(C) EMR / MSE Process (Okabe et al., 2002)

TiO2 + C → Ti + CO2

Over all reaction

(d)

Ca → Ca2+ + 2 e-Anode:

Cathode: TiO2 + 4 e- → Ti + 2 O2-

C + x O2- → COx + 2x e-

Ca2+ + 2 e- → Ca Cathode:

Anode:

Electrolysis

(c4)

(c1)

(c2)

(c3)

35

Advantages Disadvantages

Kroll Process ◎ High purity titanium available × Complicated process◎ Easy metal / salt separation Slow production speed○ Established chlorine circulation Batch type process ○ Utilizes efficient Mg electrolysis○ Reduction and electrolysis operation

can be carried out independentlyFFC Process ◎ Simple process Difficult metal / salt separation

○ Semi-continuous process Reduction and electrolysis have to becarried out simultaneously

△ Sensitive to carbon and iron contamination △ Low current efficiency

OS Process ◎ Simple process Difficult metal / salt separation○ Semi-continuous process △ Sensitive to carbon and iron contamination

△ Low current efficiency PRP (Preform ◎ Effective control of purityDifficult recovery of reductant

◎ Flexible scalability

Environmental burden by leaching

◎ Resistant to contamination○ Small amount of fluxes necessary

EMR / MSEProcess

◎ Resistant to iron and carbonDifficult metal / salt separation when oxide

○ Semi-continuous process Complicated cell structure○ Reduction and electrolysis operation

△ Complicated process can be carried out independently

××

×

×

×

××

×

×

ReductionProcess)

Features of several titanium production process

and morphology

contaminationsystem

36

Fig. Conceptual image of the new titanium reduction process currently under investigation (EMR / MSE process, Oxide system).

e-

Carbon anode

CaCl2-CaO molten salt

e-


Ca-X reductant alloy

e-

A

A

V

e-

Feed preform(TiO2 + CaCl2)

Product Ti pelletsTi (+ CaO + CaCl2)

VnCOx gas

CaCl2-CaO

TiO2 + 4 e- = Ti + 2 O2-

Ca (Ca-X alloy) = Ca2+ + 2 e-

C + x O2- = COx + 2x e-

Ca2+ + 2 e- = Ca (Ca-X alloy)

O2- , Ca2+

Ca (Ca-X alloy)

Ca

Nighttime electrolysisDaytime reduction

37

Stainless steel cover

Stainless steel plate

R reductant

Stainless steel reaction vessel

Ti sponge getter

Feed preform (MO ｘ + flux)

TIG weld

Fig. Schematic illustration of the experimental apparatus for producing titanium powder by means of the preform reduction process (PRP).

MOx + R → M + RO

1. Amount of flux (molten salt) is small.

2. Easy to prevent contamination

from reaction vessel and reductant.

3. Highly scalable.

M = Nb, Ta, TiR = Mg, Ca…

Preform Reduction Process (PRP)

38

Reductant vapor

Feed powder

Reductant (R = Ca, Mg)

(a) Conventional Metallothermic Reduction (b) Preform Reduction Process (PRP)

Reductant vapor

Feed preform

Reductant (R = Ca, Mg)

Fig. Metal powder production process: (a) conventional metallothermic reduction, (b) preform reduction process (PRP).

39

FeOx (s) + MgCl2 (l) = FeClx (l) + MgO (s)

T = 1100 K, t’ = 1 h,Atmosphere : N2,Ti ore (UGI) : 4 g, MgCl2 : 2 g

Experimental condition

Fig. Experimental apparatus for selective-chlorination of titanium ore using MgCl2 as a chlorine source.

Carbon crucible

Stainless steel susceptor

Glass beads

Stainless steel net

RF coil

Ceramic tube

Glass flange

Vacuum pump

Quartz flange

Deposit

Mixture ofTi oreand MgCl2

ChloridesCondenser

ChlorinationReactor

(FeClx ．．． )

(Fe-free Ti ore)

N2 or N2+H2O gas

Selective chlorination using MgCl2

40

FeOx (s) + MgCl2 (l) = FeClx (l, g) + MgO (s)

Inte

nsity

, I (

a. u

.)

10 30 40 50 60 70 8020

Fig. XRD pattern of the deposit at chlorides condenser. The sample powder was sealed in Kapton film before analysis.

XRD analysis

Deposit obtained after selective-chlorination. → FeCl2 was generated.

90 100

: FeCl2

XRF analysis

Residue after selective-chlorination.→ Fe was selective chlorinated.

Angle, 2θ (deg.)

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 ore (UGI from Ind.)

After heating sample

V

0.75

1.50

Ti

95.10

96.45

Fe

2.29

0.43

Si

0.41

0.44

Al

0.12

0.37

98.30 0.05 0.38 0.12 0.52After reduction sample

Results of previous study

41

Fig. Experimental apparatus for chlorination of titanium using FeCl2 as a chlorine source.

Heater

Quartz tube

Sample deposits(on Si rubber, NaOH gas trap and quartz tube)

Carbon crucible

Sample mixture:(e.g., FeCl2+Ti powder)

Ti (s) + 2 FeCl2 (s) = TiCl4 (g) + 2 Fe (s)

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

Ti

18.4

9.8

Fe

45.3

80.1

Cl

36.2

9.0

Dep. on quartz tube after heating

Dep. on Si rubber after heating

3.5 50.4 46.1

64.9 0.9 34.1

Chlorination of Ti using FeCl2

42

Fig. Flowchart of new titanium smelting process from titanium ore discussed in this study.

(CaCl2)

Ti metal

Ti smeltingby electrochemical method

This study

Low-grade Ti ore

Upgraded Ti ore FeClx(+ AlCl3)

(FeTiOx)

(TiO2)

MClx

Selective chlorinationby electrochemical method

Chlorine recovery

Fe

FeClx

TiCl4

Ti scrap

43

Iron removal process by electrochemical method

Direct reduction process from Ti ore to Ti metal can be achieved.

Establishment of a new up-grading processof Ti ore by electrochemical method.

Ae-

TiO2 Ti

e-

e- O2-

Ca-X alloy

Molten CaCl2-CaO

Carbon electrode

Ti crucible（Cathode）

Ti reduction Production of reductant

Ti ore（TiO2 + FeOｘ）

Molten CaCl2

V

Mild steel crucible（Cathode）

Carbon crucible(Anode)

A

TiFeOX

Reference electrode

e-

2. TiO2 reduction process

TiO2 + 4 e- → Ti + O2-

Ca（or Ca-X）Cathode：Anode ：

(e.g. EMR-MSE process)

→ Ca2+ + 2 e-

Selective chlorination・Iron removal process

Fen+ + n e- → Fe

2 Cl- → Cl2 + 2 e-

FeOx + Cl2

Cathode：

Anode ：Ca2+ + 2 e- → Ca

→ FeClｘ(l, g) + O

44

Fig. Schematic illustrations of the processes investigated in this study.

(a) Iron removal process

2 Cl- → Cl2 + 2 e-

FeOx + Cl2 + C → FeClx + COx

Anode:

Cathode: Ca2+ + 2 e- → Ca

Electrolysis

(a1)

(a2)

(a3)

e-

Carbon crucible containingTi ore + CaCl2 mixture (Anode)

SampleMolten CaCl2 Mild steel crucible (Cathode)

(b) FFC process (Fray et al., 2000)

C + x O2- → COx + 2x e-Anode:

Cathode: TiO2 + 4 e- → Ti + 2 O2-

Electrolysis

(b1)

(b2)

e-

CaCl2 molten salt

TiO2 preform

Carbon anode

45

@1100 K

2CaCl2 + O2 → 2CaO ＋ 2Cl2

2MgCl2 + O2 → 2MgO ＋ 2Cl2

4HCl + O2 → 2H2O ＋ 2Cl2

2CO + O2 → 2CO2

FeO + MgCl2 → FeCl2 + MgO

2C + O2 → 2CO

log pCl22 　 / 　 pO2

= -

8.29

log pO2 = -17.74

log pO2 = -19.85

e.g.

ΔG = -0.28 kJ < 0


= 1.49


=

0.48

Potential of several reaction

46

Ref.a

900 K 1100 K 1300 KFe (s ) + Cl2 (g ) = FeCl2 (s ) -228.93 [1]Fe (s ) + Cl2 (g ) = FeCl2 (l ) -212.65 [1]Fe (s ) + 1.5 Cl2 (g ) = FeCl2 (g ) -183.14 -190.89 -194.39 [1]Fe (s ) + 1.5 Cl2 (g ) = FeCl3 (g ) -236.41 -231.45 -225.62 [1]Fe (s ) + 0.5 O2 (g ) = FeO (s ) -213.15 -200.71 -188.00 [1]2 Fe (s ) + 1.5 O2 (g ) = Fe2O3 (s ) -585.32 -535.98 -486.33 [1]3 Fe (s ) + 2 O2 (g ) = Fe3O4 (s ) -821.79 -762.36 -702.25 [1]Ti (s ) + Cl2 (g ) = TiCl2 (s ) -370.38 -340.24 -310.26 [1]Ti (s ) + Cl2 (g ) = TiCl2 (g ) -258.15 262.11 -265.30 [1]Ti (s ) + 1.5 Cl2 (g ) = TiCl3 (s ) -526.31 -485.79 [1]Ti (s ) + 1.5 Cl2 (g ) = TiCl3 (g ) -495.25 -485.30 -474.73 [1]Ti (s ) + 2 Cl2 (g ) = TiCl4 (g ) -654.50 -630.68 -606.36 [1]Ti (s ) + 0.5 O2 (g ) = TiO (s ) -455.54 -437.16 -418.80 [1]Ti (s ) + 0.5 O2 (g ) = TiO (g ) -32.67 -50.63 -67.66 [1]Ti (s ) + O2 (g ) = TiO2 (s ) -780.23 -744.91 -709.30 [1]2 Ti (s ) + 1.5 O2 (g ) = Ti2O3 (s ) -1267.35 -1215.50 -1163.77 [1]3 Ti (s ) + 2.5 O2 (g ) = Ti3O5 (s ) -2052.96 -1969.32 -1885.27 [1]4 Ti (s ) + 3.5 O2 (g ) = Ti4O7 (s ) -2838.53 -2718.92 -2599.03 [1]

[1] I. Barin, Thermochemical Data of Pure Substances, 3rd ed., (Weinheim, Federal Republic of Germany, VCH Verlagsgesellschaft mbH, 1997).

Reactions Gibbs energy change, ΔG

f (kJ/mol)

a: References

Table Gibbs energy change of formation in the Fe-Ti-O system.

47

0.5 1.0 1.5 2.0 2.5

0

-2

-4

-6

-8

-10

-12

Reciprocal temperature, 1000 T-1 / K-1

Vap

or p

ress

ure

, lo

g p i

(at

m)

Temperature, T / K

Ti (s,l)

Fe (s,l)

TiC

l2 (s)

TiCl3 (s)

TiCl4 (l)

FeC

l2 (s,l)

FeCl3 (s,l)

1000 500 4002000

MgC

l2 (s, l)

CaC

l2 (s, l)

Region suitablefor vaporizationof chlorides

Fig. Vapor pressure of iron, calcium, magnesium and titanium chlorides as a function of reciprocal temperature.

48

e.g.-40

-10

-30

-20

-50

-60

0

-40 -10-30 -20 0

Fe-Cl-O system, T = 1100 K

CaO (s) / CaCl2 (l) aCaO = 0.1

C / CO eq.CO / CO2 eq.

Oxy

gen

part

ial p

ress

ure,

lo

g p

O2 (

atm

)


FeO (s)

Fe2O3 (s)

FeCl2 (l)

Fe3O4 (s)

FeCl3 (g)

Fig. Chemical potential diagram for Fe-Cl-O system at 1100 K.

FeOx can be chlorinatedby controlling oxygenand chlorine partial pressure.

Ti ore :mixture of TiOx and FeOx.H2O (g) / HCl (g)

MgO (g) / MgCl2 (l) eq.

Fe (s)

FeOX (s) + MgCl2 (l)

→ FeClX (l, g)↑ + MgO (s, l)

Thermodynamic analysis (FeOx chlorination)

49

Fig. Chemical potential diagram for Ti-Cl-O system at 1100 K.

-40

-10

-30

-20

-50

-60

0

-40 -10-30 -20 0

TiO (s)

TiO2 (s)

TiCl4 (g)

Ti2O3 (s)

TiCl3 (s)

Ti3O5 (s)

Oxy

gen

part

ial p

ress

ure,

lo

g p

O2 (

atm

)Ti-Cl-O system, T = 1100 K


CaO (s) / CaCl2 (l) aCaO = 0.1

C / CO eq.CO / CO2 eq.

Fe / FeCl2 eq.

Since TiCl4 ishighly volatile species,chlorine partial pressuremust be keptin the oxide stable region.

TiCl2 (s)

H2O (g) / HCl (g)

MgO (g) / MgCl2 (l) eq.

Ti4O7 (s)

Ti (s)

Thermodynamic analysis (TiOx chlorination)

Ti ore :mixture of TiOx and FeOx.

50

51

(CaCl2)

Ti metal


This chapter

Low-grade Ti ore


(FeTiOx)

(TiO2)

MClx


Chlorine recovery

Fe

FeClx

TiCl4

Ti scrap

Fig. Flowchart of the new titanium smelting process discussed in this study.

52

Sintered feed preform

Feed preform

Mixing

Slurry

Preform fabrication

Ti ore Flux Binder

Calcination / Iron removal

Flux : CaCl2, MgCl2

Binder: Collodion

FeClx

Fig. Flowchart of the procedure of preform fablication supplied for Fe removal experiment.

53

Table Composition of titanium ore (ilmenite) and up-graded ilmenite (UGI) used this study.

Sample name

TiO2 Fe2O3 FeO MnO Al2O3 SiO2 MgO Nb2O5 P2O5 Moisture

ilmenaiteb 52.55 20.91 15.27 1.91c - - - 0.21 0.11 0.61

UGId 95.20 0.99 0.77 0.63 0.61 0.27 < 0.01 0.10

UGIe 96.46 1.60 - 0.03 0.28 0.52 0.03 - - 0.15a: 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.

Composition (mass%)a

Total Fe

1.22

54

Table Starting materials used in this study.

Form

Liquid

Supplier

5.0

Chip 98.0up

Powder 95.0up

Collodiona

Ti

CH3COOH

CaCl2

Ca

Purity orconc. (%)

Wako Pure Chemical., Inc.

Osaka Tokusyu GoukinCo., Ltd.

Kanto Chemicals, Inc.

Sponge 98.0up Toho Titanium Co., Ltd.

Liquid 99.7 Kanto Chemicals, Inc.

Materials

a: 5 mass% nitro cellulose, 23.75 mass% ethanol, 71.25 mass% diethylether.

HCl

2-Propanol

Liquid 35 Kanto Chemicals, Inc.

Liquid 99.5up Kanto Chemicals, Inc.

Aceton

Graphite

99.0up

99.98

Liquid

Crucible



55

Experimental apparatus

Electrochemical interface

Electrochemicalcontrol unit

10 Apowersource

Sample

MoltenCaCl2

Mild steel crucible(Cathode)


Voltage monitor / controller

e-

Holes oncrucible

Furnace

56

Ceramic insulator

Thermocouple

Heater

Rubber plug

Ar inlet

Wheel flange

Reaction chamber

Preform containing Ti ore

Stainless steel tube

Molten salt (CaCl2)


Graphite crucible

Mild steel crucible

V1V2

A1A2

Fig. Schematic illustration of the experimental apparatus in a voltage measurement.

Ti ore, sample

57

Surface of molten salt

Support rod(Stainless steel tube)

Sample(Ti ore, CaCl2 etc.)

Inlet of molten salt

Screw (Stainless steel)

Graphite crucible

Air hole

Fig. Schematic illustration of the graphite crucible used in this experiment, (a) appearance, (b) inner content.

I.D. 17 mmO.D. 19 mm

40 mm

(a) (b)

58

Fig. Variation of the external current from the dipped preform to the graphite crucible.

-4

-2

0

2

4

6

8

0 500 1000 1500 2000 2500Immersion time, t / s

Imm

ersi

on c

urre

nt,

i / m

A Carbon cruciblecontaining Ti ore (Anode)

CaCl2molten salt


e-AAi

59

Fig. Electromotive force between the dipped preform and the graphite crucible.

-40

-20

0

20

40

60

80

100

120

0 500 1000 1500 2000 2500

Immersion time, t / s

Imm

ersi

on v

olta

ge,

V /

mV

Carbon cruciblecontaining Ti ore (Anode)

CaCl2molten salt


VV

60

Table Analytical results of various samplesa.

Concentration of element i, Ci (mass%)b

Fe

42.4

33.7

Ti

50.4

50.6

Ca

0.2

7.1

41.441.9 9.6

RFe / Ti (%)

84.1

66.6

98.8

AlSiCl Cr

0.90.0

0.0

3.7

5.3

2.4

2.7

0.0 4.3 2.5

0.6

0.3

40.7 36.1 10.8 88.78.7 2.0 1.3 0.3

50.1 42.2 0.1 84.30.0 4.0 3.3 0.3

Fe / Ti ratioc,

Sample #

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.

A

B

D

C

E

61

Fig. Phase diagram for the CaCl2-FeCl2 system [2].

Liquid

674℃

592℃

782℃800

700

600Tem

per

atur

e, T

/ ℃

0 100CaCl2 FeCl2FeCl2 content, xFeCl2

(mol%)20 40 60 80

62

Ceramic insulator

Thermocouple

Heater

Rubber plug

Ar inlet

Wheel flange

Reaction chamber


Molten salt (CaCl2)


Nickel quasi-reference electrode

Mild steel crucible (working)

Graphite crucible (counter)

Ti ore

A

Fig. Schematic illustration of the experimental apparatus for cyclic voltammetry in molten CaCl2.

V1 V2

63

-2

Potential (vs Ni quasi-ref.), E / V

-1 0 1

Cu

rre

nt,

i /

A

2

1

0

-1

2

1

0

-1

2

3.2 V

2 Cl- = Cl2 + 2 e- (on C)

Ca2+ + 2 e- = Ca (on Fe)

(a)

(b)

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.

64

Table Standard Gibbs energy of formation and theoretical voltage for reactions in this study.

Reactions

Gibbsenergychange,

ΔG

f / kJ

Theoreticalvoltagefor reactions,

ΔE of / V

Temperature,T / K Ref.a

Fe (s ) + Cl2 (g ) = FeCl2 (l ) -212.65 1.10 1100 [1]Fe (s ) + 1.5 Cl2 (g ) = FeCl2 (g ) -190.89 0.99 1100 [1]Fe (s ) + 1.5 Cl2 (g ) = FeCl3 (g ) -231.45 1.20 1100 [1]Fe (s ) + 0.5 O2 (g ) = FeO (s ) -200.71 1.04 1100 [1]2 Fe (s ) + 1.5 O2 (g ) = Fe2O3 (s ) -535.98 0.93 1100 [1]3 Fe (s ) + 2 O2 (g ) = Fe3O4 (s ) -762.36 0.99 1100 [1]Ti (s ) + 0.5 O2 (g ) = TiO (s ) -437.16 2.27 1100 [1]Ti (s ) + 0.5 O2 (g ) = TiO (g ) -50.63 0.26 1100 [1]Ti (s ) + O2 (g ) = TiO2 (s ) -744.91 1.93 1100 [1]2 Ti (s ) + 1.5 O2 (g ) = Ti2O3 (s ) -1215.50 2.10 1100 [1]3 Ti (s ) + 2.5 O2 (g ) = Ti3O5 (s ) -1969.32 2.04 1100 [1]4 Ti (s ) + 3.5 O2 (g ) = Ti4O7 (s ) -2718.92 2.01 1100 [1]Ca (s ) + Cl2 (g ) = CaCl2 (l ) -629.11 3.26 1100 [1]Ca (s ) + 0.5 O2 (g ) = CaO (s ) -520.78 2.70 1100 [1]CaO (s ) + C (s ) = Ca (s ) + CO (g ) -312.00 1.62 1100 [1]CaO (s ) + 0.5 C (s ) = Ca (s ) + 0.5 CO2 -323.00 1.67 1100 [1]C (s ) + 0.5 O2 (g ) = CO (g ) -209.06 1.08 1100 [1]C (s ) + O2 (g ) = CO2 (g ) -395.92 1.03 1100 [1]Fe (s ) + Ti (s ) + 1.5 O2 (g ) = FeTiO3 -956.61 1.65 1100 [1]2 Fe (s ) + Ti (s ) + 2 O2 (g ) = Fe2TiO4 -1164.70 1.51 1100 [1]

[1] I. Barin, Thermochemical Data of Pure Substances, 3rd ed., (Weinheim, Federal Republic of Germany, VCH Verlagsgesellschaft mbH, 1997).

a: Referencesb: E o = -G o / nF, where n is electron transfer number, and F is Faraday constant.

65

-1 0 1 2-2 3

Cu

rre

nt,

i /

A

-1

-1

2

1

0

2

1

0

-1

2

1

0

3.0 V

2 Cl- = Cl2 + 2 e- (on C)

Ca2+ + 2 e- = Ca (on Fe)

1.7 V

C + x O2- = COx + 2x e- (on C)

Ca2+ + 2 e- = Ca (on Fe)

1.7 V

C + x O2- = COx + 2x e- (on C)

Ca2+ + 2 e- = Ca (on Fe)

(a)

(b)

(c)

Potential (vs Ca / Ca2+ ref.), E / V

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.

66

Fig. Phase diagram for the CaCl2–Ca system [3].

Te

mp

era

ture

, T

’ / ˚

C

1200

1100

900

800

1000

700

CaCl2 Ca content, xCa (mol%) Ca20 40 600 80 100

Liq. Two liquids

825˚ 828˚

767˚

67

Sample

Molten CaCl2

Mild steel crucible(Cathode)

Carbon crucible containingTi ore + CaCl2 mixture(Anode)

e-

Fig. Schematic illustration of experimental apparatus for iron removal by electrochemical method.

68

Fig. Schematic illustration of the experimental apparatus for iron removal by electrochemical method.

V

A

Ceramic insulator

Thermocouple

Heating element

Rubber plug

Ar inlet

Wheel flange

Stainless steel reaction chamber


Molten salt (CaCl2)




Ti ore

69

S L

Ti ore ( + Fe2O3 etc)

Electrochemical iron removal

Leaching

TiO2 powder

CaCl2

Waste solution

CaCl2

TiO2 + CaCl2

TiO2

Vacuum drying

Separation

CH3COOH aq.,HCl aq.,Distilled water,Isopropanol,Acetone

Fig. Flowchart of the procedure for iron removal experiment by electrochemical method.

Distilled water

70

Experiment 1

Experimental condition：Temperature: 1100 KAtmosphere: ArMolten salt: CaCl2 (800 g)Cathode: Mild steel crucible (I.D 96 mm)Anode: Graphite crucible (I.D 17 mm)

Sample

MoltenCaCl2

Mild steelcrucible(Cathode)


Voltage monitor / controller

Mass of Ti ore(Ilmenite), w / g

A 4.00B 4.00

4.00C

Voltage,E / V

Time,t’ / h

2.52.01.5

63

12

Exp. No.

e-

71

Result 1

XRF analysis

After the electrochemical treatment, Fe in the Ti ore was selectivelychlorinated and removed.

Table Analytical results of the sample obtained after the electrochemical selective chlorination.Concentration of element i,

Ci (mass %)

VTi Fe Ca Si

Ti ore 0.642.6 48.7 2.2 2.2

Exp. A 0.964.2 29.6 0.5 1.8

Fe / Tiratio,

114

49.5

Disscussion

Ti ore (Ilmenite, FeTiOx)

Molten CaCl2

Graphite crucible(Anode)

Unreacted part

Unreacted part wasremained at the bottomof the graphite crucible.

Exp. B 1.255.4 25.3 13.8 1.1 45.6

Exp. C 2.745.7 21.7 12.3 1.4 47.4a: Average of the samples obtained from the upper part and lower part of the graphite crucible.

RFe / Ti (%)

e-Sample

72

Mass of feed materials i, wi / g

Table Experimental condition for iron removal from Ti ore by electrochemical methodc.

UGIa

A

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.

Exp.

B

Ilmeniteb

C

D

E

F

G

2.76

2.82

2.91

2.88

2.81

2.75

2.92

2.0

1.2

0.5

2.0

1.0

0.5

1.0

1.0

1.0

1.0

3.0

6.0

0.5

1.0

Voltage, V / volts

Reaction time,t / hr

H

I

J

K

L

M

N

4.00

4.03

3.99

4.00

3.93

4.01

4.01

2.5

1.5

1.0

0.5

ー

1.5

1.5

3.0

3.0

6.0

6.0

6.0

9.0

6.0

O

4.00 2.0 13.01.42 1.2 1.0 P

Mass of feed materials i, wi / g

UGIa

Exp.

Ilmeniteb

Voltage, V / volts

Reaction time,t / hr

73

Fig. Schematic illustration of electrochemical interface in this experiment.

10 APowerSource

20 cm

74

Fig. Current generated by imposed each voltage.

Time, t / second

Cur

rent

, I /

A

0 10000 20000- 0.5

0

0.5

1.0

1.5

2.0

Exp. K

Exp. L

Exp. M

Exp. N

75

Exp. Noteb

# Al Si S Cl Ca Sc Ti V Mn Fe NiUGIc

0.0 0.1 nd 0.0 0.1 nd 96.3 0.2 1.0 1.9 0.0 2.00 051227-UGIAUSUGIc 0.4 1.1 0.5 nd 0.1 0.4 92.8 1.2 1.3 2.3 0.0 2.45 050125_UGI

A 0.2 0.4 0.0 nd 38.8 0.2 55.4 1.1 0.4 2.6 0.8 4.65 050125_UGI_P04_1B nd nd nd nd nd nd nd nd nd nd nd nd 050119_UGI_P02C 0.3 1.1 0.1 nd 15.3 0.1 80.2 1.4 0.3 1.3 0.0 1.63 050125_UGI_P05_2D 0.2 0.9 0.0 nd 5.3 0.3 90.1 1.0 0.9 1.3 0.0 1.40 050125_UGI_P06_1E 0.2 0.4 0.0 0.0 45.7 0.2 49.8 1.5 0.6 1.6 0.1 3.27 050125_UGI_P07_2F 0.2 0.8 0.0 nd 30.4 0.1 66.4 1.1 0.4 0.6 nd 0.98 050127_UGI_P10_1G nd 0.1 0.1 nd 11.3 0.1 86.5 1.5 0.2 0.2 nd 0.24 050119_UGI_P01_1H 0.1 0.2 0.0 nd 21.4 0.1 76.4 1.1 0.2 0.4 0.0 0.56 050119_UGI_P03_1b

Ilmenited 1.8 1.8 0.0 nd 0.2 0.2 44.8 0.7 3.3 47.2 0.0 105.3 050420_ilmenite



Ilmenited 1.0 1.4 nd nd 0.2 0.4 45.0 0.5 3.0 48.5 0.1 107.9 050607_ilmeniteI 1.1 0.5 0.0 0.1 9.0 0.3 53.8 0.9 0.9 33.3 0.1 61.9 050425_ilmenite_P33_2J 0.9 1.5 0.1 nd 6.4 0.2 56.0 0.7 0.7 33.5 0.1 59.9 050428_ilmenite_P38_1K 1.0 6.2 0.1 nd 8.1 0.1 58.1 1.1 0.9 24.0 0.5 41.3 050217_ilmenite_P15_1L 1.3 4.5 0.1 nd 21.5 0.1 56.7 1.2 0.8 12.8 0.9 22.6 050217_ilmenite_P14_1M 1.2 2.8 0.1 0.4 20.2 nd 46.7 0.8 1.6 26.1 0.1 55.8 050216_ilmenite_P13_3N 1.2 1.9 0.0 1.7 35.4 0.1 37.7 0.7 0.6 20.5 0.0 54.6 050216_ilmenite_P12_2O 0.1 0.2 0.0 0.2 35.3 0.3 49.1 1.0 1.0 12.8 nd 26.0 050517_ilmenite_P46_2P 0.1 0.5 0.0 0.1 28.5 0.2 41.4 0.8 1.5 26.7 nd 64.6 050516_ilmenite_P45_1Q 0.6 0.6 0.0 0.2 33.4 0.2 52.2 1.2 0.7 10.8 nd 20.7 050502_ilmenite_B_1

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%)

Fe / Ti/ %

Composition i , C ia / mass %

Table Analytical results of the samples obtained after iron removal by electrochemical method.

76

Ceramic insulator

Thermocouple

Heater

Rubber plug

Ar inlet

Wheel flange

Stainless steel tube (Electrode)

Molten salt (CaCl2)

Potential lead (Ni wire)


V1V2

A1A2


Ti ore + CaCl2 mixture

100 mm

Fig. Schematic illustration of experimental apparatus in this experiment.

77

Fig. Current value passed by imposed certain voltage, and voltage in this experiment, Exp. F.

0

2

4

6

8

10

12

0 3000 6000 9000 12000Time / s

Curr

ent / A

0

0.5

1

1.5

2

2.5

3

Volta

ge / V

Current

Voltage

78

Fig. XRD pattern of the obtained sample after selective chlorination experiment.

Inte

nsity

, I (

a. u

.) : CaTiO3

(JCPDS #42-0423)

Angle, 2θ (degree)

: TiO2

(JCPDS #21-1276)

100908070605040302010

79

Table Experimental condition and analytical results of the chlorination experiment using ilmenite.

Exp. Ilmemite Carbon CaCl2 Noteb

- Ilmenitec- - - - - - - 105.5 - 050420_ilmenite

A 1.25 - 1.80 2.0 1.5 3 2.52 54.8 0.85 050610_P48B 1.87 - 1.33 1.0 1.8 6 1.72 74.8 1.26 050613_P49C 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_P53E 0.79 - 2.00 3.7 2.0 6 5.09 - - 050725_P55F 0.87 - 2.35 3.7 c c 5.91 7.2 0.97 050803_P56G 3.99 - - - 2.0 3 3.60 54.9 2.60 050811_P57H 0.77 - 2.18 4.0 1.5 3 5.87 57.4 0.48 050811_P58I 0.77 0.18 2.14 4.0 1.5 3 3.09 24.7 0.03 050814_P59J 0.74 - 2.12 4.0 1.5 3 4.49 48.8 0.76 050816_P60K 0.74 - 2.17 4.0 1.5 3 5.00 3500 0.02 050816_P61L 0.72 - 2.19 4.0 - 6 - 34.2 0.55 051014_P62M 0.73 - 2.20 4.0 0.0 6 -0.004 48.7 0.55 051014_P63N 0.62 - 2.26 5.0 1.5 3 0.68 46.2 0.37 051017_P64O 0.61 - 2.25 5.0 1.5 6 0.42 37.7 0.41 051018_P66P 0.74 - - - 1.5 3 0.47 72.7 0.56 051019_P67Q 0.73 0.16 2.00 3.7 2.5 6 1.95 - - 051020_P69R 0.74 - 2.17 4.0 2.5 6 1.81 12.4 0.42 051021_P70S 0.60 - 2.26 5.0 1.5 3 1.27 107.0 0.31 051025_P72T 0.60 - 2.21 5.0 2.0 6 0.79 126.8 0.59 051025_P73U 0.60 - 2.21 5.0 d d 4.10 354.4 0.02 051026_P74V 0.67 - 2.37 5.0 e e - 12.9 0.38 051114_P75

a: Indicator of iron removal from titanium ore. b: Experiment numberc: Ilmenite (FeTiOx) produced in China.d: 2.0 volts 20 minutes, and 1.5 volts 3hourse: 1.8 volts 6 hours, and 3.0 volts 3 hoursf: 2.0 volts, 1.5 volts, 1.8 volts, and 2.0 volts, 1 hour respectively

Obtainedsample,w / g

Mass of feed material i , w i / g

1

Usebath #

CaCl2 / FeOx

ratio,M Ca / Ti / -

Imposedvoltage,

V / volts.

Reactiontime,t / hr

Averagecurrent,

I / A

Fe / Ti

ratioa,R Fe / Ti / %

3(Old)

4

80

Table Experimental conditions and analytical results of the chlorination experiment using UGI.

Exp. UGIa CaCl2 Notec

- - - - - - - 2.00d - - 051227_UGIAUSA 1.55 1.27 20 2.0 3 - - - 051219_P77A 1.59 1.26 20 2.0 3 0.28 0.09 0.13 051222_P89B 2.08 0.84 10 2.0 3 - - - 051219_P79B 2.07 0.83 10 2.0 3 4.70 0.15 0.20 051221_P87C 2.46 0.49 5 2.0 3 - - - 051220_P82C 2.46 0.49 5 2.0 3 7.41 0.42 0.25 051221_P86D 1.59 1.27 20 1.5 3 0.18 0.49 0.35 051220_P81E 2.11 0.85 10 1.5 3 0.59 0.55 0.14 051219_P78F 2.45 0.48 5 1.5 3 - - - 051220_P84F 2.45 0.48 5 1.5 3 0.83 1.11 0.29 051221_P85G 2.12 0.58 7 1.5 9.5 0.33 0.76 0.16 051220_P80H 2.08e 0.83 10 1.5 10 - - - 051222_P88

4 I 1.57 1.28 20 f f 2.20 0.02 0.42 051115_P76J 1.59 1.24 20 0.0 3 2.63 1.95 0.05 051220_P83K 1.59g 1.27 20 2.0 6 0.43 0.31 0.15 051222_P90

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 numberd: Referencee: Mixture 2.08 g of Ti ore and 0.08 g of carbon powderf: 2 volts 2 hours, and 2 volts 2hoursg: Up-graded ilmenite by the Benilite process (see Fig. 1-5). The ore was produced in India.

5

5

Mass of feed material i , w i / gUsebath

#

Obtainedsample,w 1 / g

Mass decrease ofcarbon crucible,

w2 / g

CaCl2 / FeOx

ratio,M Ca / Ti / -

Imposedvoltage,V / volts

Reactiontime,

t / hour

Fe / Ti

ratiob,R Fe / Ti / %

81

(CaCl2)

Ti metal


This chapter

Low-grade Ti ore


(FeTiOx)

(TiO2)

MClx


Chlorine recovery

Fe

FeClx

TiCl4

Ti scrap

Fig. Flowchart of new titanium smelting process from titanium ore discussed in this chapter.

82

Ceramic insulator

Thermocouple

Heater

Rubber plug

Ar inlet

Wheel flange

Reaction chamber


Molten salt (CaCl2)


Mild steel crucible

Ti crucible (Cathode)

Mixture of Ti oreafter Fe removal and CaCl2

A

Fig. Schematic illustration of the experimental apparatus for electrochemical reduction of Ti ore after Fe removal.

V

Graphite rod (Anode)

83

S L

Ti ore (+Fe2O3 etc)

CaCl2 Mixing

Electrochemical reduction

Leaching

Ti powder

Waste solution

Mixture

CaCl2

Ti + CaCl2

Vacuum drying

CH3COOH aq.,HCl aq.,Distilled water,Isopropanol,Acetone

Fig. Flowchart of the experimental procedure for electrochemical reduction of Ti ore after Fe removal.

84

Table Experimental conditions for electrochemical reduction of Ti ore after Fe removal.

Mass of feed material i, Ci / g

Ti ore CaCl2

2.50R1

R2

R3 0.79a

2.50

2.50

Voltage,E / V

Time,t” / h

1.5

3.0

3.0

3

3

3

CaTiO3

R4 2.50 3.0 3

1.50

1.50

ー

0.76b

Exp. No.

ー

ー

ー

a: The sample obtained by selective chlorination exp. A.

b: The sample obtained by selective chlorination exp. D.

85

Fig. Phase diagram for the CaCl2–CaO system.

1150 K

1000

950

900

850

800

750

700

CaCl2

10 20

CaO content, xCaO (mol%)30

CaO 0

Te

mp

era

ture

, T

’ / ˚

C

Documents

1 2006 Annual Meeting, San Antonio, TX, U.S.A, March 12–16, 2006 Iron Removal from Titanium Ore by Electrochemical Method Isao Obana 1 and Toru H. Okabe