USRE17430E - Preparation of titanium hydroxide - Google Patents

Description

' 45 (from thepoint Reissued Sept. 10,1929.

UNITED; STATES PATENT OFFICE.

JOSEPH momentum), or rARrs, FRANCE, ASSIGNOR, BY mnsnn ASSIGNMENTS, To 1 ooIrmnnoI L 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, filed February 4, 1924.

' Application for reissue filed June 12, 192B. Seria1 No. 284,679..

DmsIoN B.

The invention relates to the hydrolytic treatment of solutions of titanium oxide in sulfurio acid with the object of preparing the hydroxide of titanium. a v 5 Such solutions are obtained by treating titaniferou's products or minerals, such as ilnienite, with sulfuric acid.

The chemical composition of these solutions may vary within fairly wide limits. The two most important variables are the concentrations of TiO and H 80 Solutions containing from 100 to 400 grams TiO per liter are of the usual strengths to be treated. For a molecule of'TiO the solution should contain 12 or even more molecules oi; H SO It has nowbeen found that the yield of titanium hydroxide obtained by hydrolytic precipitation of such solutions (heated to 10 about 100 C. during a certain time) as wellas its properties, such as the rate of decantation, filtrability, state of subdivision of grain, color after calcination, etc., depend not only on the final state of the system subjected to Z5 hydrolytie treatment but they depend also upon certain transformations which the constituents of the solution undergo before and during the precipitation of the titanium I dioxide andalso upon the way in which this final state of reaction is brought about. In efiect, the solution of TiO; in H SO brought to a desired concentration either b dilution or byconoentration, is heatedto'the ing point in orderto produce the 'hydrolysis and becomes opaque after a comparatively long time, but if the content in H,,S O combined'with T10 neglecting other bases, is

equal to or exceeds 100 grams per litre, a very V npoor yield in titanium hydroxide is obtained.

40 Moreover, the precipitate thusobtained, even if possible,'is only filtered with great difliculty.

fore is tov obtain a satisfactory precipitate of. view .ofyield', I filtra ility v and other roperties) in' a shorttiine from solutions 0 the type mentioned above even in Y high concentrations. i

The invention cons stsinpre aring P lium oxideor hydrox de by,

boil-, i

. the concentrated solution.

The object of the present inventionptlierel mixing. The mixin 1y quickly in order t cipitation by diffusion of titanium from one solution into another under the action of diiferential concentration and preferably also temperature.

Theinvention further consists in preparing titanium-oxide or hydroxide by hydrolytic precipitation by diliusion of titanium from one solution into another accelerated by mixing.

1 v The invention also consists in applying the above processes inthe presence of other substances so that intimately mixed precipitates are obtained.

Generally, the methods employed are as follows: a

(1) The solution obtained by reacting on the titanium material with sulphuric acid, heated to a temperature excee'dingfiO? 0., is coveredwith a layer of cold water or hot water, either pure or containing such I substances as may favor the process such, for example, as H 50 H PO,, A1;, (S0,) S0,, or: even a solution of titanium salt of a different concentration. The quantity of the 1iq-,, uid added is calculated so as to produce on diffusion or mixing together the desired concentration. The liquid is introduced in such .a' manner that the two liquids 'may mix together only gradually, and thus within a certain timethere will be a difit'erence in concentrations in diflerent parts of the solution as regardsH SO and TiO (2) In another or modified method the solution is concentrated by evaporatin or boiling and may even become thick 1i e a paste. When the necessary quantity of water has been eliminated according to the object, the solution is mixed with a smaller, equal 'or larger quantity of water than that eliminated. One of the liquids must be at that time at a temperature above 60 C.-usually The water may be 'pureorfcontaining some substances, such as titanium salt or the like. The proportions of v the two liquids are selected so as to have the desired concentration, both in 'TiO and H,SO in the final state after the complete at the titanium hydroxide does noflprecipitate appreciably etore should be efiected fair the homogeneity of the solution is achieved and heating continued.

In both cases the hydrolytic precipitation is terminated at a temperature not far from .the boiling point of the solution and in a titanium hydroxide is precipitated. in presence of other substances adapted to serve as constituents of paint pigments, (such as BaSO CaSO SiO and the like) with which it is desired to mix it very intimately. The added substances may be prepared separately or in the same apparatus in which the hydrolysis takes place.

ing temperature, eva oration being Example 1. The solutioncontaining Gr. per litre. TiO ".225 Fe 50 H,SO tota1 44.0

isheated to 9598 and alayer of cold water is placed on the top in quantity correspond ing to about 20 per cent of its volume. This amount of water is suflicient to reduce the total H 80 content to about 367 rams per litre. The mixture of the liquid is acilitated by a gentle agitation. The liquid becomes titanium sulfate with a solution of lesser concentration, and retarding the rate of admixture so that the composite 1i uid first becomes gradually turbid and therea r throws down the desired precipitate.

2. The preparation of titanium dioxide or hydroxide by hydrolytic precipitation which comprises bringing together a solution of titanium sulfate with water, and retarding the rate of admixture so that the composite liquid first becomes gradually turbid and thereafter throws down the desired precipitate. 1

3. The preparation of titanium dioxide or hydroxide by hydrolytic precipitation, which fate with a layer of solution o'flesser concentration so that the composite liquid becomes gradually turbid and thereafter throws down the desired precipitate.

4. The'preparation of titanium dioxide or hydroxide by hydrolytic precipitation, which comprises introducing cold water into a Warm solution of titanium sulfate in that proportions of about 20% of the volume of the titanium sulfate solution and in such 'a manner as to form a layer of-water upon the titanium sulfate solution.

JOSEPH BLUMENFELD. T

gradually turbid and then a precipitate falls down. By the end of a few hours the yield of titanium hydroxide is about 94: per cent.

Example Q. The solution containing:

Gr. per litre. Ti0 Fe 4:2 H SO, 460

is concentrated by evaporation to half its volume. It then has the consistency of a paste. It is introduced into about twice its own volume of boiling hot water so that the concentration finally will be 300-310 gr. H SO per litre. The mixing is effected in'such a manner as to avoid the immediate coagulation (precipitation) by delaying the mixing from 3 to 5 minutes. It is maintained at boilrevented. In-about hal an hour a yield? of 85-95 percent of titanium hydroxide is obtained. 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 comprises covering a solution of titanium sul