J Electrounal Chem.. 199 (1986) 207-210

Elsewer Sequoia S.A.. Lausanne - Printed m The Netherlands 207

Short communication

ELECTRODEPOSITION OF TITANIUM AND ITS DIOXIDE FROM ILMENITE

L.H. MADKOUR *

Cherntsty Department, Faculiy of Sctence, Tantu lJmaerst&, Tunta (Egvpt)

A.S. FOUDA

Chemtstn Department, Faculty of Sctence, Mansouro Unwerstty, Munsour~~ (Egvpt)

(Recewed 15th April 1985: in revised form 13th September 1985)

INTRODUCTION

The aim of the present work was to develop a simple and rapid electrolytic extraction process of titanium [l-3] and its dioxide from the ilmenite ore of the Eastern Desert. The ore mother liquor used for the electrolysis process is either produced by direct leaching with 98% H,SO, (S/L = 1 : 15), 35% HCl (S/L = 1: 20) and alkaline digestion with caustic soda in a ball-mill autoclave at 175°C under a pressure of 9.5 kg cmP2, or it is prepared through the fusion method using NaOH or Na,S,O, separately as fluxes at 600-700°C.

EXPERIMENTAL

Ti and TiO, were prepared by electrodeposition on platinum sheets as described previously [3-61. All the chemicals used were of BDH Analar grade and were used without further purification; 0.1 M ore leach chloride and sulphate were prepared from doubly distilled water and their concentrations were determined as given by Vogel [7].

RESULTS AND DISCUSSION

Baths suitable for the electrodeposition of Ti and TiO, are indicated in Table 1. The production of titanate and its dissolution are assumed. The effects of current density, complexing agents. ammonium salt, temperature and current efficiency were studied. Also, we confirmed the presence of positively and negatively charged complex species by carrying out experiments using the ion-exchange resin technique

l To whom correspondence should be addressed.

0022-0728/86/$03.50 ‘a 1986 Elsewer Sequoia S.A

TA

BL

E

1

Suita

ble

bath

s fo

r th

e el

ectr

olyt

tc

extr

actio

n of

ttt

aniu

m

and

its d

ioxr

de

from

rl

men

ite

ore

Bat

h C

ompo

sttio

n of

ele

ctro

lyte

so

lutio

n

(in

500

cm3

ore

liquo

r)

PH

Cur

rent

Pr

oduc

t C

ompl

ex

spec

tes

Cur

rent

R

ecov

ery

dens

ity/

efft

cten

cy

/W

mA

cm

e2

/%

Sulp

hate

Chl

orid

e

Am

mon

ia

Bor

ate

Ace

tate

Tar

tara

te

Bro

mid

e

Fluo

ride

Oxa

late

Ure

a

Sodi

um

hydr

oxid

e

Ore

le

ach

sulp

hate

(0

.1

M)

and

20 c

m3

1 M

H

,SO

.,

Ore

le

ach

chlo

ride

(0

.1

M)

and

10 c

m3

perc

hlor

ic

acid

Ore

le

ach

chlo

nde

(0.1

M

),

60 g

NH

,CI

and

NH

,OH

(1

: 1)

Ore

le

ach

chlo

nde

(0.1

M

).

60 g

NH

,CI,

3 g

bora

x an

d N

H,O

H

(1:

1)

Ore

le

ach

chlo

ride

(0

.1

M),

30

g N

H,C

l,

50 c

m3

(1 M

) ac

etic

ac

id

and

NH

,OH

(1

: 1)

Ore

le

ach

chlo

ride

(0

.1

M),

40

g N

H,C

I,

50 c

m3

(1 M

) ta

rtan

c ac

id

and

NH

,OH

(1

: 1)

Ore

le

ach

chlo

ride

an

d 20

cm

3 2

M

HB

r

Ore

le

ach

chlo

ride

(0

.2

M).

50

g

NH

,CI,

N

aF

and

NH

,OH

(1

: 1)

Ore

le

ach

chlo

ride

(0

.1

M).

60

g N

H,C

l,

50 c

m3

(1 M

) ox

alic

ac

id

and

NH

,OH

(1

: 1)

Ore

le

ach

chlo

ride

(0

.1

M)

and

5 g

urea

Ore

le

ach

chlo

nde

(0.1

M

),

60 g

NaO

H

and

15 c

m3

glyc

erol

[Ti(

OH

),HSO

,]‘+

[Tt(

OH

)Cl,

+TI]

‘+

FXN

H3)

,13+

[Ti(

B40

7)12

’

4.0

250

T1

99.3

96

.2

3.8

240

TI

99.4

95

.6

9.0

200

Ti

98.7

97

.1

9.0

400

7.5

230

Tl

TI

99.6

94

.3

99.8

96

.2

5.0

250

TI

[TK

&$H

,)I’

+

99.6

93

.4

4.0

300

Ti

[Tt(

OH

)Br2

+

Ti]

j+

99.4

94

.7

8.0

200

99.2

95

.2

8.0

600

8.0

300

TiO

2

[TC

,)12

-

Ti

[Ti(C

,Q,

)12’

T

i lT

WW

H,)

,),1

3+

99.5

96

.3

98.6

94

.5

10.0

30

0 T

I [T

i(O

H),

]”

99.4

93

.8

209

[8,9]. The structures of titanium complexes of the type [Ti(NH,),13+ were proved [lo]. Also, the tartarate 1111, oxalate 1121, bromide, chloride 1131, perchlorate 1141, sulphate [14], urea [14] and fluoride [15] [Ti(F,)12- complexes of titanium were identified and proved conductometrically. The formation of Ti and TiO, is dis- cussed. The results of chemical and spectrophotometric analyses indicate that the purity of titanium is 99.1%. Also the electron micrograms confirmed by the X-ray standard tables (ASTM) for TiO, coincide well with those given by chemical analysis.

The reaction of ilmenite ore with NaOH and its dissolution in H,SO, and WC1 can be represented as follows:

FeTiO, + 2 NaOH + Na zTiO, + Fe0 +H,O

(1) NaZTiO, C 3 H,S04 -+Ti(SO,),+Na,SO,+3 H,O

Ti(SO,), + H,O + TiOSO, + H *SO,

(2) Na,TiO, + 4 HCI -+Ti(OCl)z+2 NaCl +2 Hz0

Ti The following equation represents the mechanism of formation of the element

from the different baths used 1161:

Ti(L)“++ ne”-+Ti+L

where L is the ligand of the complex species and n is the number of positive charges on the species. Adsorption of hydrogen ions and complex species on the surface of Ti protects it from oxidation.

During the deposition of TiO,, the complex species [TiF612- migrated towards the anode, where it loses its negative charge and dissociates yielding Ti4’ ions. These ions are oxidized by the OH. radicals at the anode to form TiOz [17].

[TiF612- +Ti4++6 F-

Ti4++ 2 H,O~TiO~+4 H” i

Effect of current density At low current density (200 mA cme2}, only a thin layer of Ti was deposited and

an oxide with low oxygen content was obtained in the case of TiO, deposition. At higher current densities (> 400 mA cm-‘), a non-adherent and randomly oriented deposit [18] of Ti and an oxide with higher oxygen content were obtained. Suitable current densities for cathodic and anodic deposition are shown in Table 1.

Effect of complexmg agent/metal ion ratto

Smooth deposition of bright grey-silver Ti was obtained at low concentration ( = 0.1 M) of complexing agent. Also, the adsorption of complexing agents at the cathode prevents the oxidation of Ti.

Effect of ammonium salt Ammonium salt acts as a buffering medium for the bath; it assists the stability of

the Ti complexes. prevents the precipitation of Ti hydroxide as the pH is raised. and increases the conductance of the solution.

Effect of temperature Increasing the temperature from 25 to 50°C favours the deposition of Ti and TiO,

owing to the acceleration of both the ionic migration of the complex species and the oxidation of Ti” at the anode.

Current efficiency In the ammonia and urea baths the current yield is nearly 99%. The platinum

plate and the dilute solution of Ti are responsible [19] for the current yield being

slightly lower than 100%.

ACKNOWLEDGEMENT

The author would like to thank the Egyptian Geological Survey and Mining Authority. A.R.E.. for kindly supplying a sample of the title ore.

REFERENCES

1 T. Hammada. Japanese Patent. 2357 (55). 11 Apnl (1957) 51.

2 N.T. Kudryavtsev and R.G. Golovchanskaya, USSR Patent 127. 10 March (1960) 121.

3 AS. Fouda. M.M. Elsemongy and I.M. Kenawy, Indtan J. Technol.. 20 (1982) 139.

4 AS. Fouda, J. Electroanal. Chem.. 110 (1980) 357.

5 AS. Fouda and M.M. Elsemongy. J. Electroanal. Chem.. 122 (1981) 279.

6 L.H. Madkour. J. Chem. Tech. Biotechnol., 35 A (1985) 108.

7 A. Vogel. Quantitative Inorganic Analysis, Wiley. New York, 1975, pp. 6088615.

8 A.S. Fouda. 3. Electroanal. Chem., 110 (1980) 357. 9 M.M Elsemongy, M.M. Gouda and Y.A. Elewady, J. Electroanal. Chem., 79 (1977) 376.

10 D. Negoiu, Acad. Repub Pop. Rom. Stud. Cercet. Chim., 11 (1963) 71.

11 S.P. Biswas, T.S. Krishnamoorthy and C. Venkateswarlu. Indian J. Chem., 14 (1976) 592.

12 Ya. S. Kamenlsev, Probl. Sovrem. Anal. Khim., 1 (1976) 60.

13 A.G Stromberg and A.I. Kartushmskaya. Fiz. Khtm. Anal.. Akad. Nauk SSSR. Sibirak Otd Inst

Neorgankhrm., (1963) 315.

14 F.A. Cotton and G. Wilkinson, Advanced Inorganic Chemtstry, 3rd ed.. Wiley. New Delhi. 1976, p.

810

15 Ya.A. Buslaev, V.A. Boekbareva and N.S. Nikolaev, Izv. Akad. Nauk SSR Otd. Khim. Nauk. 3 (1962) 388.

16 M.M. Elsemongy, Y.A. Elawady. M.M Gouda and A. Elasklany. J. Electroanal. Chem., 84 (1977) 359. 17 AS. Fouda, J. Electroanal. Chem., 114 (1980) 83.

18 I.F. Ntchkov. S.P. Paspopin and V.I. Devyakkin, Tr. Ural. Politekh Inst., 121 (1962) 18.

19 AS. Fouda and M.M. Eisemongy, J. Electroanal. Chem.. 124 (1981) 301.