. ‘Re. 17,430v

' Reissued Sept. 10,1929.

PATENT OFFICE.

UNITED; STATES

JOSEPH momentum), or rARrs, FRANCE, ASSIGNOR, BY mnsnn ASSIGNMENTS, To 1

ooIrmnnoIAL rremnn'rs CORPORATION, A‘ CORPORATION or DELAWARE. PREPARATION or rirANIuM nrnaoxrnn; No Drawing. Original 1T0.~ 1,504,672, dated August 12, 1924, Serial No. 690,658, ?led {February 4, 1924. _ '

Application for reissue ?led June 12, 192B.

Seria1.No.'284,679..

>

'

DmsIoN B. by diffusion of titanium from one The invention relates to the hydrolytic cipitation solution into another under the action of . treatment of solutions of titanium oxide in sulfurio?acid with the object of preparing diiferential concentration and preferably also the hydroxide of’ titanium. ' a v further consists ‘in prepar 5 Such vsolutions are obtained by treating ingTheinvention titanium-oxide or hydroxide by hydroly titaniferou's products orwminerals, such as tic precipitation by diliusion of titanium ilnienite, with sulfuric acid. The chemical composition of these solu from one solution into another accelerated temperature.

‘

>

'

'

.

55

‘ by mixing.

tions may vary within fairly wide limits. 1 v The invention also consists in applying the 60' 10 The two most important variables are the above processes in‘the presence of other sub

concentrations of TiO2 and H280‘.

Solutions containing from‘ 100 to 400 grams stances so that intimately mixed precipitates obtained. _ ' ‘ . \ '. TiO2 per liter are of the usual strengths to areGenerally, the methods employed are as _be treated. For a molecule of'TiO2 the solu 65 15 tion should, contain 1—21/2or even more mole ‘cules oi; H2SO4. "

follows:

-

'

a

'

(1) The solution obtained by reacting on -

titanium material with‘ sulphuric acid, It has now‘been found that the yield of the heated to a temperature excee'ding?O? 0., is titanium hydroxide obtained by hydrolytic covered‘with a layer of cold water or hot precipitation of such solutions (heated to water, ‘either (pure or containing ' such I sub~

10 about 100° C. during a certain time) as well ‘stances as may favor the ‘process such,yfor, as its properties, such as the rate of decanta

70'

as H2504, H3PO,, A1;, (S0,) 3, S0,, tion, ?ltrability, state of subdivision of grain, example, or: even a solution of titanium salt of a differ color after calcination, etc., depend not only ent concentration. The quantity ‘of the 1iq-,, on‘ the ?nal state of the system subjected to added is calculated so, as to produce on Z5 hydrolytie treatment but they depend also uid diffusion or mixing together the desired con upon certain transformations which the con centration. The liquid is introduced in such stituents of the solution undergo before and .a' manner that the two liquids 'may mix to during the precipitation ‘of the titanium gether only gradually, and thus within a cer

I

_ dioxide and- also upon'the way in which this ’ timethere will be a di?t'erence in concen 30 ?nal state of reaction is brought about. In tain trations in di?erent parts of the solution as ‘ e?ect, the solution of TiO; in HZSOU brought regardsHZSO4 and TiOz. -_ / to a desired concentration either b dilu _ tion or byconoentration, is heatedto'the boil-, i (2) vIn another or modi?ed method the

75

st

is concentrated by evaporatin or ing point in ‘order- to produce thev'hydrolysis ‘solution boiling and may even become thick 1i e a '85

35 and becomes opaque after a comparatively paste. _ When the necessary quantity of water -,

long time, but if the content in H,,S_OM com~ has been eliminated according to the object, ' bined'with T102, neglecting other bases, is

_

V

equal to or exceeds 100 grams per litre, a very '

‘the solution is mixed with a smaller, equal

quantity of water than that elimi npoor yield in titanium hydroxide is obtained. 'or largerOne of the liquids must be at that n6 40 Moreover, the precipitate thusobtained, even nated. time atla temperature above 60°v C.—-usually

if possible,'is only ?ltered with great di?i

culty.

‘

"

'

'

'

‘

"

'

. ‘the concentrated solution. The water may be

some substances, such as The object of the present inventionptliereli" 'pureorfcontaining titanium salt or the like. The proportionsiof

fore is tov obtain a satisfactory precipitate the two liquids are selected so as to have the 51‘‘v of. view .ofyield', I ?ltra ility

' 45 - (from thepoint

_ Y

concentration, both in 'TiOz and . _ . v and other rope’rties) ‘in'la shorttiine from desired _H,SO‘, inv the ?nal state after the‘ complete solutions 0 the type mentioned above even‘ in - mixing. The mixin should be e?ected fairs ; '1 high concentrations. .'

'

i

'

The invention consistsinpre‘ aring ' P0 Ilium‘ oxideor hydroxide by, _

quickly in order t at the titanium hydrox .3 51y ide doesfno?precipitate appreciably etore ,

H- b0 .

2

17,430

the homogeneity of the solution is achieved titanium sulfate with a solution of lesser con ‘ centration, and retarding the rate of admix In both cases the hydrolytic precipitation ture so that the composite 1i uid ?rst becomes

and heating continued.

is terminated at a temperature not far from gradually turbid and therea

.the boiling point of the solution and in a constant volume. The'yield of the precipi

the desired precipitate.

r throws‘ down

.

'

2. The preparation of titanium dioxide or

tate ‘reaches 85-95 per cent in a few hours in hydroxide by hydrolytic precipitation which the ?rst ease and less than in one hour in the comprises bringing together a solution of

10

second. Thevarious properties mentioned titanium sulfate with water, and retarding above are greatly improved, such as ?ltra the rate of admixture so that the composite bility "as Well as the stability of the mother liquid ?rst becomes gradually turbid and liquor at dilution. ‘ ' _ thereafter throws down the desired precipi These methods are equally valid when the

tate.

.

‘

75

1

titanium hydroxide is precipitated. in pres- ' 3. The preparation of titanium dioxide or 15 ence of other substances adapted to serve as hydroxide by hydrolytic precipitation, which 80 constituents of paint pigments, (such as ‘comprises covering a solution of titanium sul— BaSO“ CaSOM SiO2 and the like) with fate with a layer of solution o'f‘lesser concen

which it is desired to mix it very intimately. tration so that the composite liquid becomes The added substances may be prepared sepa gradually turbid and thereafter throws down

2,0 rately or in the same apparatus in which the the desired precipitate. ' hydrolysis takes place. 4. The'preparation of titanium dioxide or

hydroxide by hydrolytic precipitation, which

Example 1. 25

comprises introducing cold water into a Warm solution ofv titanium sulfate in that

, The solutioncontaining : Gr. per litre. TiO2__

Fe__

'__'__'

___

‘

____

.____

85

,

___

__

".225

_____

50

H,SO4tota1____ ____________________ __ 44.0

30 is‘heated to 95—98° and alayer of cold water

is ‘placed on the top ‘in quantity correspond;

proportions of about 20% of the volume of

90

the titanium sulfate solution and in such 'a manner as to form a layer of-water upon the

titanium sulfate solution.

JOSEPH BLUMENFELD. T 95

ing to about 20 per cent of its volume. This amount of water is su?icient to reduce the 35

total H2804 content to about 367 - rams per

litre. The mixture of the liquid is gacilitated by a gentle agitation. The liquid becomes

100

gradually turbid and then a precipitate falls , 40

down. By the end of a few hours the yield of titanium hydroxide is about 94: per cent.

Example Q.

105

The‘ solution containing: _ ‘

'45

.

Gr. per litre.

Fe Ti02 __________________ _.._. ‘ _._ _._| __ __________ __ _.._. _

4:2

HZSO, _~__'___' ____ _; _____ __._ _________ __ 460

50

is concentrated by evaporation to half its vol- ' ume. It then has the consistency of a paste. It is introduced into about twice its own volume of boiling hot water so that the con

no;

115

centration ?nally will be 300-310 gr. H2SO4 perqlitre. The mixing is effected in'such a manner as to avoid the immediate coagula

tion (precipitation) by delaying the mixing from 3 to 5 minutes. It is maintained at boil

120

ing temperature, eva oration being re vented. In-about hal an hour a yield?) of 85-95 percent of titanium. hydroxide is ob 60

tained.

-

,

I

_

. Now, having fully described my invention, I claim the following as new and novel: - 1. The preparation of titanium dioxide or

.hydroxide by hydrol'ytio precipitation which

comprises bringing together a. solution of

130