US1489417A - Titanium compound and its manufacture - Google Patents

Description

Patented Apr. 8, 1924. v

UNITED STATES TITANIUM COMPOUND ITS MANUFACTURE.

No Drawing. Application filed March 28, 1919,

To all whom it may concern:

Be it known that I, FRANK E. BACHMAN, a citizen of the United States, residing at Port Henry, county of Essex, and State of New York, have invented a new and useful Improvement in Titanium Compounds and Their Manufacture, of which the following is a full, clear, and exact description. The present invention relates to certain titanium compounds and their manufacture.

' These compounds which may be'either the end products or intermediate products in the process are titanium compounds resembling metatitanic acid.

The object of the invention is to pro duce a product of the character described economically and in a substantially pure condition. I i

In the following description the process is outlined beginning with the raw titanium bearing ore and end ng with the final purified product, which is a soft impalpable opaque white powder which resembles metatitanic acid and titanium dioxide, but apparently difi'ers from metatit-anic acid 1n containing less combined water and from pure titanic dioxide, in that it contains some combined water, is free of grit and is more readily soluble in sulphuric acid. It is to be undeistood, however, that the process is not limited to the entire sequence of steps from the raw ore to the final'product, but that a fewer number of steps may be employed. For example, the steps of purification of the titaniferous precipitate thrown down by boilin the titaniferous solution,

, may be employs in purif ing such titaniferous precipitate produce by other methods than that constituting the preliminary steps herein specifically described. Also some ofv the steps of purifying the titanium compounds may be omitted.

The resent invention is not limited to the fina end product herein described and its preparation, but ma be employed in the production of the soeca ledinterediateproducts herein described, which of themselves are articles of manufacture and which may be considered as the final dproducts in case their production is desire The process of the present invention will be .first outlined beginning with the raw material or ore, then the rocess and the products will be more speci cally described.

The raw material preferably used in ilmenite, either mined as such or obtained as PATENT OFFICE.

FRANK E. BACHMAN, 0]? PORT HENRY, NEW YORK.

Serial No. 28 5,873. Renewed September 4, 1923.

a by-product from the concentration of titanium bearlng ore, as, for example, t1- tanium bearmg 110I1 ores, vast deposits of which exist containing from 10 to 40% ihnenite, 25 to 80% magnetite and 5 to 50% gangue matter. An average composition of HEiSSUED' such ore is 36% ilmenite, 48% magnetite and 14% gangue matter.

The 'ore is crushed to pass a quarter inch mesh, and the product passedthrough magnetic separators, in which the greater part of the magnetite passes into the heads and the greater part of the ilmenite and ganguc matter into the tails, the magnetite becoming available for use in blast furnaces for the production of pig iron. The ilmenite.

in the tails is found to be so separated'from the gangue matter -as to be readily recoverable by the well known method of jigging or tabliilg, whereby an ilmenite sufliciently pure for my process is obtained at a low cost from a heretofore waste product.

An approximate analysisof ilmenite so obtained has been 48.50% TiO 36.64%

Fe(); 6.04% Fe O '.68% A1 0,; 3.70%

stance obtained from the waste liquors in making sulphite wood pulp, is useful for this purpose. The mixture of pulverized ilmenite and coal is charged into retorts which are heated by external heat, the heat being preferably obtained from the gas produced by burning in gas roducers the excess carbon which had en mixed with former charges to carbon monoxide and us ing such carbon monoxide by burning it around the retorts. The heat 'so applied drives off from the coal its volatile constituentsin the form of gas which contains valuable. by-products which may be recovered. The carbon combines with the oxygen of the-iron oxides to form carbon monoxide which mixed with the combustiblegas of the coal becomes available for heating, drying, etc. in the subseguent steps of the process.- The products 0 combustionused to heat the retort leave the retort furnace The reaction leaves a spongy residue in the retort consisting essentially of metallic iron, titanium dioxide and carbon, together with gangue matter, and more or less unreduced or partially reduced iron oxides. This reaction product or residue is lixiviated or digested with a dilute solution of the l1q u1d produced in one of the later steps of the process, the liquid being that remaining after the intermediate titanium compound is se1 rated. This liquid consists essentially of di ute sulphuric acid carrying with it some ferrous sulphates and such small amounts of titanium sulphates as may have failed to decompose. The "sulphuric acid reacts with the iron to form ferrous sulphate which passes into solution leaving a solid residue which is a titanium concentrate consisting of carbon, titanium dioxide, some undissolved iron and. iron oxides, and the greater part of the gangue matter. This titanium concentrate is then separated from. the solution, digested with strong sulphuric acid, whereby the titanium dioxide is converted intotitanic and titanous sulphates and the iron into ferrous sulphate. The titanic and titanous sulphates and the ferrous sulphates are dissolved in \vaterand then separated from the solid matter remaining The solid matter remaining consists of carbon and the insoluble portions. of the ilmenite. It is compressed While still damp into briquets which are dried and utilized for fuel. The ash from these briquetswhen pulverized may be used as a paint pigment. The titanium bearing solution is then heated which precipitates the titanium content as an impure modified metatitanic acid which is separated from the liquid. The residual liquid contains the sulphuric acid which was combined with the titanium and containsin the form of ferrous sulphate the iron which was not dissolved from the reaction product, together with such portions of the gangue matter as were more readily soluble and any small quantity of the titanium sulphate which failed to decompose. dissolve the iron contained in the reaction product as hereinbefore described. Theportion of the solution not so used, is concentrated, the free sulphuric acid recovered and the residue added to the ferrous sulphate solution, which is then boiled, whereby the residue is dissolved and the small quantity of titanium sulphate contained therein decomposed, the titanium separating as an impure metatitanic acid, which is separated 'atitanic acid may Part of this solution is used to made after treating the titanium concentrate Y with the strong sulphuric acid :This-precipitate may be used as an article of manufacture and strongly heated to obtain crude titanium dioxide suitable for such purposes as making titanium electrodes, or this precipitate may be further purified. A further purification is had by digesting the preci itate with dilute hydrochloric acid to issolve and thereby removing the small amount of basic iron sulphates contained. The precipitate is then freed from the hydrochloric acid solution. I

The precipitate as thus purified may be dried and used as an article of manufacture. It is a soft opaque amorphous powder, white or of a creamy tint. This compound is apparently a modified meta-titanic acid containing a small amount of combined S0 It differs from titanium dioxide in that it contains combined water, and from meta-titanic acid in that it contains less combined water. This partially purified modified metbe used as an intermediate product, and still further purified to remove the decomposable combined sulphuric acid. When it is to be further purified, it is used damp as separated from the hydrochloric solution and further digested with a substance which has a stronger atfinity for sulphuric acid than has basic titanic sulphate, to substantially free it from the remaining sulphuric acid compounds. There are many substances which may be used for this purification. I prefer, how.-

ever, to use a substanc which is soluble in water and whose resulting sulphates is also soluble, such a substance being for example an'alkalme hydrate or carbonate. The resulting purified productis a compound resembling metatitanic acid, which compound I term m modified metatitanic acid. 'It consists of titanic dioxide combinedwith some water, and free from iron and basic titanic sulphate. When this is heated to a temperature sufficient to expel a greater part of the combined water but not sufficient to render it hard and gritty, it becomes a'soft amorphous exceedingly opaque product, white or having a delicate creamy tint, more suitable for pigments than titanium dioxide products heretofore produced. v

The ferrous sulphate solution produced as a by-product is concentrated and runinto crystallizing pans in which the ferrous sulphate crystallizes out of the mother liquor, and when separated from the mother liquor may be sold as the green vitriol of commerce. The mother liquor may be treated if desired for the recovery of magnesium sulduring the operation.

i to dilute the acid solution used in the step. The acid solutions used are those prophate by methods known to those skilled in portions of ilmenite and coal owing to vari-- able quality of coals. The requirements are to have enou h coal to furnish an excess of carbon to re uce the iron oxides to metallic iron and an excess suflicient to make a coke strong enough to permit easy lixiviation of the product but not so dense as to prevent the acid solution reaching all parts of the lumps into intimate contact with each particle of the ilmenite.

.The mixture, of pulverized coal and ilmenite is then charged into a retort. For this purpose I prefer a retort of the type used in the production of illuminating gas by the continuous process, wherein the coal is charged as the coke produced is withdrawn, the coke being cooled in an extension of the retort to below its ignition temperature. The'heat for such a retort may be furnished by the combustion of the gas produced in a gas producer. I have used a retort heated electrically by resistance. The coal and ilmenitemixture is charged as the reaction product is withdrawn, the withdrawals being so timed that the mixture remains in the'heated bone of the retort for six hours or more. .The bottom of the retort is sealed against ingress of air between withdrawals. The temperaturewithin the retort is maintained approximately at 1200 centigrade When thetmixture comes into the heated zone the coal softens and gives off its volatile matter, and when heated to about 750 centigrade the reduction of the iron oxide begins, metallic iron forms and carbon monoxide gas is given off.

The reaction product as withdrawn from. the retort consists of metallic iron, carbon, titanium dioxide gangue matter and some coal ash. This reaction product is charged into lixiviation vessels preferably so arranged that the reaction product is first treated with a solution containing ferrous sulphate and almost free from free sulphuric acid and afterwards with solutions contain ing less ferrous sulphate and more free sulphuric acid. In solutions in the lixiviation of the reaction product. In the first four sulphuric acid was used and in the fifth .water only, the wash water used in the fifth step being used ourth duced at a later step in the process ass byproduct, being the solutions separated from ractice I have used five the crude modified metatitanic acid precipitate. Sufiicient water is added to these solutions" to reduce the free sulphuric acid content to about a nine or ten percent solution.- The contents of the lixiviating vessels is preferably kept at a temperature between and 80 centigrade. After washing with water the solid matter is drained as free from water as possible. This'solid matter forms my .titaniumconcentrate. An analysis on one occasion showed that after drying at 100 centigrade it had approxi: mately the following composition: I

57% TiO 8.5% Fe o 1.4% A1 0 4%v MgO: 2% CaO; 22% carbon; 4% SiO,; 1% volatile matter and water.'

The'solution containsthe soluble iron as ferrous sulphate, together with a little silica and magnesia, and in the case analyzed also contained about 2.2% of the titanium dioxide charged. in combination as titanous sulphate. The solution also contains some of the titanium concentrate and the carbon in suspension. To this solution is added the solid residue left after concentrating and distilling that portion of the sulphuric acid which is not used to treat the concentrate. of ferrous sulphate with a small amount of ferric and titanic sulphate, together with such portions of thegangue matter as passed into solution. The ferric sulphate is generally present in sufficient quantities to oxidize the titanous sulphate in the iron solution to titanic. sulphate, and the ferrous sulphate in sufficient quantity to fully saturate the solution. The solution is then heated in an iron vessel to theboiling point where upon the titanium content quickly precipitates as a'crude metatitanic acid. Owing to the presence of gelatinous silica which acts as an agglomerant, the metatitanic acid, silica, carbon and undissolved concentrate which has passed through the lixiviating vessel, settles rapidly. The clear solution is run into crystallizing pans in which the ferrous sulphate is recovered; In this way I recover about 90% of the iron contained in v the ilmenite as green vitriol, a valuable article of commerce. The metatita'nic acid is drained. The solution is added to the fer- This ,solid residue consists rous sulphate solution, the solid matter to.

the titanium concentrate.

Referring now to the titanium concentrate remaining after the acid lixiviation of the retort reaction product This titanium concentrate is brought into resisting pressure and so arranged that the contents may be stirred, a cylindrical vesgester.

sel hung on trunnions and having internal battles has been found suitable. The contents of the digester are heated, 'preferably by a gas flame which may be readily controlled, until the temperature of the contents reaches 165 to 175 centigrade, whereby the excessive water is expelled. The digester is left open up to this point, thenthe digester is closed and the heating continued under pressure until the temperature of the coin tents reaches 200 to 225 centigrade. During this heating the contents of the digester is stirred, preferably by rocking the di- The heating at 200 to 225 centigrade is continued for about an hour, after which the contents are allowed to cool to about 100 centigrade or less, and the wash water from the treatment of a previous batch by the second step, to be hereafter described, is added and the stirring continued meanwhile. The product so obtained is removed from the digester and drained free from the solid matter. This solution contains the titanium content with the exception of such titanium content as may remain in the solid matter. The solution thus obtained has a specific gravity of approximately 1.3. It consists essentially of titanic sulphate and ferrous sulphate, together with small quantities of magnesium and aluminum sulphate and silica. In some cases there is a small amount of titanous sulphate, while in other cases I have obtained solution free from titanous sulphate but containing small amounts of ferric sulphate.

The digestion under pressure brings the iron 1nto solution n its ferrous state, and thereby saves the cost of later reducing ferric to ferrous iron.

The solid matter remaining after the first step j ust' described, is further treated to recover the remaining titanium content. This solid residue while still damp and contain- I ing 30 to 40% of water, is transferred to an iron vessel to which is added sufficient sul phuric acid to theoretically convert the iron, titanium, magnesium, and aluminum contained in the concentrate into sulphates. The mixture is gradually heated with occasional stirring to 200 centigrade or over, which temperature is held for sometime,

about one-half hour generally being sufficient. By this means the greater part of the titanic dioxide and iron not converted into sulphates in the first step, are converted into sulphates and pass into the solution, together with a portion of the magnesia and alumina.

I Some of the silicates are decomposed, the silica becoming gelatinous. The acid is then drained from thesolid matter, preferably on an asbestos suction filter. The sulphuric acid drained off is used in the first step of digesting the titanium concentrate. The solids are washed with water using about three and onehalf times by volume of the After drying the briquets to about 325 Centigrade they were found by one analysis to have approximately the following com position: 5% volatile matter and water; fixed carbon; and 35% ash.

The ash was about 8% by weight of the ilmenite and its composition was found to be in the oase analyzed about 38.5% SiQ 48% TiO 3.5% A1 0,; 8% Fe O and 1.8% MigO. The ash left after burning the briquets is a yellow brown powder, slightly gritty, which when ground with a drying oil forms a'paint especially suitable for application to metallic surfaces.

In the first step it was found on one analysis that about 86% of the titanium content of the ilmenite passed into a solution, and in the second step about 6% passedinto a solution, leaving about 8% undissolved in the residue. On other occasions I have obtained as high as.96% of titanium in the solution, leaving less than -i% in the residue.

Referring now to the sulphuric acid solution containing the titanium content digested from the titanium concentrate: If this solution contains titanous sulphate in excess, the greater part or all of it is oxidized to titanic sulphate, the titanic sulphate thus produced is normal titanic sulphate having the formula Ti(SO,),. For this purpose the solution is aerated until the characteristic color of titanous sulphate has almost but not entirely disappeared. Air is used in preference to oxidizing chemicals on account of its lesser cost. If ferric sulphate is presout it is reduced to ferrous sulphate, preferably by electrolysis, carrying the reduction to a point where traces of titanous sulphate show. A small quantity of sulphurous acid basic iron sulphates and basic titanium 5111-- phate precipitated in the next step in which the crude metatitanic acid is precipitated. I When heated to its normal boiling temperature the titanium content of this solution is not precipitated as a titanic hydrate or as a basic titanic sulphate. The titanium content is precipitated by heating the solution to above its normal boiling point. 7

The solution is then run into a'lead vessel enclosed in a boiler containing a small quannium compound, which resembles metatitanic acid, and which I call my modified metatitanic acid.- The temperature necessary for the decomposition of the titanic sulphate into sulphuric acid and my new titanium compound varies, being dependent upon the percentage of free sulphuric acid contained in the solution and the quantity of sulphuric acid set free by the titanic sulphate. F or example, a titanic sul hate solution of 1.3 specificgravity containing .0792 grams TiO and .0149 grams Fe per cubic centimeter was not completely decomposed when heated for' two hours at 147 centigrade, but when a like solution was heated to 160 centigrade for thirty minutes, the

titanium was completely separated from the solution. A like solution diluted with water to 1.1 specific ravity was completely freed from TiO aft r heating for thirty minutes at 135 centigrade It is to be understoodtherefore, that the above temperature may be varied to meet the conditions encountered. Heretofore it has been customary to dllute I the sulphuric acid solution of the titanium and afterwards to heat such dilute solution to its atmospheric boiling point. The dilution has been necessary in order to permit the precipitation to take place. when so heated. The precipitate thus obtained by heating the dilute solution has been metatitanic acid. In myprocess instead of diluting the solution, I take the solution'as formed by the previously described steps, which solution may have a specific gravity as high as 1.3, or even as high as 1.42, and heat such solution in the closed vessel above its atmospheric boiling point to precipitate the titanium content. The heating above the atmospheric boiling point permits a' more concentrated solution to be employed than heretofore used, and thereby reduces the amount of solution to be heated to from one-fifteenth to one-eighth of that necessary under the former practice of using dilute solutions and heating them to the atmosphcric boiling point. My process also results in the formation as the precipitate of my new titanium compound hereinafter described which has less combined water than the metatitanic acid heretofore precipita'ted by heating the dilute solutions.

The titanium compound is then separated from the liquid b filtration or otherwise. The compound w en dried forms a soft opaque amorphous powder which is white or of a creamy tint when derived from so lutions containing a large proportion of iron. An analysis of a typical sample of this compound showed it to contain .08% Fe O 2.68% 80,; 7.75% combined water and 89.59% TiO When this titanium compound is dried at 100 (1, it has a definite composition ranging between 84 to 94% TiO,,, 1 to 5% S0 traces to 2% Fe O and 4 to 10% H O.

This new titanium compound produced may be used as an article of manufacture, or it may be still further purified as hereinafter described. Also the following steps may be used to purify metatitanic acid or modified metatitanic acid produced by other processes, the steps of purification process not being dependent upon the specific process employed for producing the metatitanic or modified metatitanic acid.

Starting now with the modified metatitanic acid produced'by the preceding process (or metatitanic acid produced by other processes), the modified metatitanic acid is first purified by hydrochloric acid treatment to remove iron impurities. The modified metatitanic acid compound is transferred .while still damp, into a hydrochloric acid resisting digester and to it is added a small quantity of hydrochloric acid 25% by volume of its liquid contents being ample, and

if not already contained approximately 2% by volume of the liquid of sulphuric acid,

sulphuric acid is added to make up this percentage. The material is then digested with occasional stirring at a temperature of about 80 to 100 centigrade until the basic iron sulphates pass into the solution. The

material during digestion is of the consis tency of thick cream. During digestion I prefer to make successive additions of nitric acid to the amount of about a to 1% by volume of the hydrochloric acid used. The sulphuric acid is added to prevent titanium compound from becoming of a colloidal nature and the nitric acid is added to oxidize ferrous to ferric iron and todestroy any organic matter if present. The solid matter is then drained and washed with water until free from the dissolved iron. The compound so purified may be used as an article of manufacture, or may be still further purified as hereinafter described.

This coin ound is distinguished from titanium dioxi e in that it contains more combined water, less TiO and more S0 and is distinguishedfrom metatitanic acid in that it contains more TiO 'and less' combined water. My belief is that it is essentially modified metatitanic acid containingfi molecules of TiO combined with one molecule of H 0, a lesser quantity containing 5 molecules of TiO and more than 1 molecule of H 0, together with basic titanic sulphate in varying quantities and small amounts of impurities.

It is of especial value as an intermediate compound from which may be produced the titanium pigment on titanic dioxide hereinafter described.

The compound above described is next still further purified by the removal of combined sulphuric acid therefrom. The step now to be described of removing the combined sulphuric acid may be applied to a modified metatitanic acid produced by steps other than those hereinbefore specifically described, or maybe applied to the purification of metatitanic acid, or to the purification of partially ignited metatitanic acid, that is metatitanic acid from which a portion but notall of its combined water has been expelled. The material to be purified is transferred to a digester capable of resisting pressure. If the material to be purified is my modified metatitanic acid compound, produced by the foregoing steps, it is transferred to the digester while still damp.

' bined as basic titanic sulphate.

- use only such of these substances as roduce Enough water is added to bring the material to a paste and then the substance that will combine with the sulphuric acid content is added. The sulphuric acid is believed to exist in the modified metatitanic acid com- The treatment now described transfers the SO, contained in the basic titanic sulphate to the base of the purifying substance used. I find that there are a number of such purifying substances which may be used. For examgle, the alkaline hydrates, the more readily ecomposable acetates, metallic oxides and hydroxides, many of the carbonates, such as those of sodium, potassiunnlead, zinc calcium, etc., and the chlorides of the alkalineearths preferably in the presence of hydrochloric acid.

For the production of a white pigment I a soluble sulphate or a white insolu lesulphate. I find that certain of the substances are more active than the others, in that they will combine with a portion of the S0 at the temperatures obtainable at atmospheric pressures. I find. however, that to obtain a satisfactory result, it is preferable to conduct the digestion at temperatures above 100 centigrade. 'is a satisfactory purifying substance to use I find that caustic soda for this purpose. Enough water is added to the solids to make a paste of about the consistency of thick cream. Then a slight excess of the purifying substance such as caustic soda is added above the theoretical amount necessary to combine with the S0 present to form a sulphate of the substance added, for example, to form Na S'O, when caustic soda is used. The digester is then closed and heatis applied until the temperature reaches about seventy pounds per decomposition of the titanium sulphate, and

it may be determined by trial for the particular conditions encountered. When the titanium compound acted on contains an excess of' combined water, the water content is reduced during the above operation. After cooling, the solid matter is washed free from alkali and the sodium sulphate and then dried. By this treatment, when caustic soda is used, the basic titanic sulphate is decomposed apparently forming titanium dioxide, ortho titanic acid and soluble sodium sulphate, which is removed by the washing.

The resultant product of this purifying treatment is my modified metatitanic acid freed from the deleterious basic titanic sulphate. when dried at centigrade, of titanium compounds containing 5 nioleculcs of Ti() and 1 molecule of combined water, together with varying quantities of modified metalltanic acid containing more than 1 molecule '7 of water. The impurities, if any, are 111- significant amounts of 810,, A1 0,, Fe.

I believe that it consists essentially v ortho titanic acid, TiO and undecomposed basic titanic sulphate. It is a soft amorphous opa ue powder free from gritty substances an in color white or of a delicate creamy tint.

It is distinguishable from metatitanic acid in that it contains less combined water and is distinguishable from pure titanic dioxide in that it contains combined water, is free from grit and is more readily soluble in sulphuric acid. \Vhen used as a pigment it has greater covering and hiding qualities than lead and zinc pigments. It is not poisonous, it is not discolored by sulphureted hydrogen and it will carry a larger proportion of inerts than will lead or zinc piiments.

Iv investigations lead me to believe that the basic titanic sulphate present in metatitanic acid, modified metatitanic acid, or partially ignited metatitanic acid. is of varying composition, a portion of it being so stable that it does. not decompose when mixed with drying oils when applied as a paint, and another portion being unstable. The portion not removed by the aforesaid treatment, if any, is the stable portion.

The compound may be dried at a temperature .of 100 centigrade and used as a pigment, or it may be heated to a temperature sufiicient to decompose the metatitanic acid. driving off its combined water but not suflicient to render the titanium dioxide thus produced hard and gritty. Atemperature of between 550 to 600 centigrade is suflicient for this.

Referring now to the solution from which the modified metatitanic acid was separated by heating I In one typical case this solution was found to have a specific gravity of about" sulphate which was not decomposed in the treatment, and a small amount of silica.

The solution-not used for dissolving the iron in the reaction product I concentrate in lead pans to any desired strength. During the concentration the greater portion of the ferrous sulphate,together with some forric sulphate produced by atmospheric oxidation, separate. The solution is drained into retorts and distilled. The sulphuric acid passing off is condensed and made available for further use. In previous methods used for the production of titanium dioxide, the sulphuric acid has been generally 10st. By my method 85 to 90% is recovered and utilized in the production of useful products, such as green vitriol, which are recovered for future use. The solid matter remaining-in the retort after distillationcontains ferrous and ferric sulphate, the

titanic sulphate which failed to separate from the solution and the greater part of the magnesium and aluminum sulphates, and some gelatinous silica. This solid matter is added to the iron solution. The sulphate of magnesium remaining in the mother liquor may be recovered if desired.

As will be readily appreciated by those skilled in this art, the process hereinbefore described produces a purer article and one better adapted for use than processes heretofore used. The general process heretofore used of making metatitanic acid has been to bring the titanium bearing materials into hydrochloric or sulphuric acid solution, then freeing the solution from excessive acid, reducin any iron to ferrous iron, di-

-- luting the so ution until the titanium con- Analysis The proportion of these basic sulphates varies. Numerous analysis proye, however, that the S0 present reachesfrom 5 to 10% and the Fe O present from a trace to 5%.

The presence of S0,, in metatitanic acid thus separated from sulphuric acid solutions, has long been known as is noted in A System of Quantitative ,Chemical y Dr. C.'Remigius Fresenius, John Wylie and. Sons, New York,1877,' sec.

107, page 178. When this has been used in the preparation of titanium dioxide. pigments it hasbeen found that when mixed with drying oils and applied with a paint, the basic titanic sulphate gradually decomposes, setting free sulphuric acid, and thes'ulphuric acid in turn acts on the oil whereby the paint becomes discolored. It has been proposed to drive off the S0 by heat.

When metatitanic acid containing this impurity is heated, it gives oil the greater part of its combined water at a temperature below 450 centigrade. At 550 centigrade the basic sulphates begin to decompose, SO being volatilized and TiO re-' maining. The sulphates continue to be decomposed until the temperature reaches about 850- centig-rade, at which there is little or no further ,'deco1nposition by heat alone, although an'appreciable quantity of SO still remains. When the metatitanic acid is thus heated, it. rapidly loses its pigment qualities about 600 centigrade by changing from a soft amorphous powder to a hard gritty substance, relatively unsuitedfor use as a pigment. On the other hand,

when heated to a temperature which is sufficient .to remove relatively all of the combined Water but not all of the S0 if ground in oil, it will, if sufliciently free from iron, produce a paint which will be white when applied but gradually change color to a dirty yellow. This change in color I believe to be due to the action of the I sulphuric acid set free by the decomposition.

of the basic titanic sulphate remaining.

Paint made from my modified metatitanic acid or-from my titanic dioxide purified as hereinbefore described, is free from any deleterious amounts of basic titanic sulphate, and retains its original color. The pigment is free from any gritty matter and has as great,'if not greater, hiding capacity than any paint heretofore known.

While the process has been fully and specifically described in all its steps, begln ning with the treatment of the titanium bearing ore to the final purification, it is to be understood that the process is not lim ited to one having all of the steps specifically set forth, but that fewer number of steps may be applied. Also the proportions; temperatures, etc., may be varied as found desirable. It is to be understood, therefore, that the present invention is not limited to the details set forth in tlie'foregoing description, but may be otherwise employed within the scope of the following claims.

I claim:

1. Those stepsiof the herein described which dissolves the iron leaving the titanium content in the residue, digesting the residue with an acid of sufiicient strength to dissolve the titanium content and forming a solution I i of the titanium content, and heating the solution to precipitate the titanium content, substantially as described.

2. Those steps in the herein described process of treating titaniferous materials which consist in mixin an iron and titanium bearing material with carbonaceous material. which when charred leaves a spon 'y residue, heating the mixture to reduce t e contained iron to a metallic state, and leaching the reaction product thus obtained with an acid which dissolves the iron and leaves the titanium content, substantially as described.

3. Those steps in the herein described process of treating titaniferous materials which consist in mixing an iron and titanium bearing material with carbonaceous material, heating the mixture to reduce contained iron to a metallic state, treating the reaction product thus obtained with an acid which dissolves the iron and leaves the titanium content in the residue, digesting the residue with strong sulphuric acid to dissolve the titaniumcontent and forming a solution of the titanium content, heating the solution to precipitate the titanium content, treating the precipitate with dilute hydrochloric acid and'with a substance -which has a greater aflinity for sulphuric acid than basic titanium sulphate, substantially as described. I

4. Those steps in the herein described process of treating titaniferous materials which consist in purifying a hydrated ti-.

taniumoxide by treating it with dilute hydrochloric acid, and thereafter treating it with a substance which has a greater aflinit for sulphuric acid than basic titanium su phate, substantially as described.

5. That step in the herein described process of treating titaniferous materials which ing as an impurity atitanium sulphate with a substance which has suflicient afiinity for sulphuric acid to break up the titanium sulphate and combine with the sulphuric acid,

substantially as described.

7. Those steps in the herein described process of treating titaniferous materlals which (-onsistsin forming an acid solution containing titanium and some iron impurities, heating the solution to precipitate the titanium content and treating the precipi- 'tate with dilute hydrochloric acid to dissolve the iron contained in the precipitate, substantially as described.

8. Those steps in the herein described process of treating'titaniferous materials which consist in forming an acid titaniferous solution, precipitating the titanium content from such solution, and treating the precipitate with a substance which combines with suchacid as may be combined with the precipitate, substantially as described.

9. .Those steps in the herein described process of treating titaniferous materials which consist in forming a sulphuric acid titaniferous solution, precipitating the titanium content from such solution, and treating I the precipitate with a substance which has a greater afiinity for sulphuric acid than basic titanium sulphate, substantially as described.

10. Those steps in the herein described process of treating titaniferous materials which consist in digesting a titanium bearing material with strong sulphuric acid and then treating the mixture with water to form a dilute sulphuric acid titaniferous solution, heating the solution to precipitate the titanium content as a hydrated titanium oxide, and thereafter treating the precipitated hydrated titanium oxide with a dilute acid which will dissolve iron impurities in the precipitate but leaves the hydrated titanium oxide substantially unafl'ected, substantially as described.

11.. That step in the herein described process of, treating titaniferous materials which consists in heating a titaniferous solution containing an excess of free acid under pressure so as to precipitate the -titanium content as a modifiedmetatitanic acid, substantially as described.

12. That step in the herein described r process of treating titaniferous materials which consists in forming a titaniferous acid solution of such concentration that the titanium would not be precipitated by heating the solution to its atmospheric boiling point, and in heating such solution under pressure to above its atmospheric boiling point so as to precipitate the titanium content, substantially as described.

13. That step in the herein described process of treating titaniferous materials which consists'in heating a titaniferous sulphuric acid solution having a specific gravity of. at least 1.1 under pressure to above its at mospheric boiling point so as to .1 recipitats the titanium content, substantia ly scribed. v

' 14. That step in the herein-described process oftreating titani'ferous materials which and in such a manner as-to preci itate the titanium content, substantially as escribed. 16. Those steps in the herein described process of treating titaniferous materials which consist in forming a titaniferous reaction product containin metallic iron, treating such reaction pro uctwith acid to dissolve the iron, digesting the residue with acid to dissolve the titanium content, treat-' ing this solution to precipitate the titanium content therefrom,,and using the acid solution from which the titanium content was precipitated to treat a fresh batchof the reaction product, substantially-as described.

17. Those steps in the herein described process of treating titaniferous materialswhich consist in forming a titauilerous re action product containing reduced metallic .iron, treating this reaction product with which consist in puri sulphuric acid to dissolve the reduced iron, digesting the residue with strong sulphuric acid to dissolve the titanium content, thereafter so manipulating this titaniferous solution as to precipitate the titanium' con tent therefrom, and using the waste sulphuric acid solution from which the titanium content has been precipitated to treat a "fresh batch or the reaction product, substantially as described.

18. These steps in the herein described process of treating titaniferous materials a hydrated titanium oxide of combine sulphuric acid, and thereafter heating the purified hydrated titanium oxide to drive ofi the combined water; substantially as described.

19. That step in the .herein' "described process of treating titaniferous materials process of treating titaniferous materials .which consists in digesting a ferrugiuous titaniferous material with strong sulphuric acid'under heat and pressure in a closed vessel whereby the titamum content is dissolved and the iron content is dissolved as ferrous sulphate, substantially as described.

20. That step in the herein described v me osis as de the iron content into solution in its ferrous which consists in digesting a ierruginous tita'uiierous material with acid under heat andpressure in a closed vessel so as to dissolve the titanium content and also bring state, substantially as described 21. These steps in the herein described process of treating titanilerous, materials, which consist in mixing a titaniierous material containing iron oxides with a carbo-' naceous material, treating the mixture by heating it so. as to reduce the contained iron to a metallic state but without changing the chemical combination of the titanium, and leaching the reaction product thus obtained with an acid which dissolves the iron but leaves the titanium content, substantially as described.

22. That step in process oil treatin which consists in eatin asolution of titanium sulphate containing free acid and substantially free from ferric salts to a temperature above its normalboiling point so as to precipitate the titanium content, substantia 1y as described.

23. That step in the herein described the herein described titaniferous materials 5 process of treating titaniferous materials which consists in heating a solution of titanium sulphate substantially free from ferric salts and containing hydrochloric acid and a reducing agent to above its normal boiling point, so as to recipitate the titanium content,substantialy as described.

24. That step in the herein described process of treati titanilerous materials,

which consists in lasting a titanium solu tion which contains some titanous sulphate to a temperature above its normal boilin point so as to precipitate the titanium content, substautia ly as described.

25. As a new article or manufacture, a white amorphous powder consisting of a hydrated titanium oxide containing less than 10% of combined water, substantially as described.

26. As a new article of manufacture, a

are

hydrated titanium oxide containing less than 10% of combined water, substantially as described.

27. As a new article or tiallyfreefrom combined sulphuric acid, substantially as described.

llllii I manufacture, a hydrated titanium oxide containing less than 10% of combined water and substan-' 28. As a new article of manufacture, a

hlydrated titanium oxide containing less. 1'.

an 10% of combined water and substantially free from iron and combined sulphuric acid, substantially asdescribed; y

.29. That step in the herein described process of treat" titaniterous materials titani'ferous solution, precipitating the ti tanium content from such solution, puritywhich consists in orminga sulphuric acid.

ing the precipitate of combined sulphuric 26311 by treating it with a substance which has a greater afim'ty for sulphuric acid than basic titanium sulphats, and thcrcaftcr heating the purified precipitate to drivc'ofi the combined Water; substantially as dcscribcd.

30, That star; in the herein described pros css of treating" tits-microns matcrisl, W? 31 consists in heating a titanic solnhats stion above its normal boiling; so as p1 clpitatc the in content, substantially as dcscribcd, o,

3 1. That the heroin dcscribcd PE'GQ ass of trestingtitanifsrcus consists in heating titanic sulphatc solution ontaining so no tits-nous s to a tom raturc shows its normal boiling so as prccioitatc the titanium 'contcnt, substantially ss. described.

32. Those steps in the herein described process of treating titaniferons materials, which consist in adding a reducing agent to a titanic sulphate solution and then heatingthe solution above its normal boiling point so as to precipitate the titanium content, substantially as described.

33. Those steps in the herein described process of treating titaniferous materials, which consist in adding hydrochloric acidto a titanic'sulphate solution and heating the solution above its normal boiling point so as to precipitate the titanium content, substantially as described.

34. Those steps in the herein described process of treating titaniferous materials, which consist in adding hydrochloric acid and a rcducin agent to a titanic sulphate solution, and eating the solution above its normal boiling point so as to precipitate the t'taninm content, substantially as dcscrihed.

35. lhat stop in the herein described process of treating titanifcrous materials, which consists in hosting a titanium solution. which will not precipitate at its normal boil temperature to a temperature abort: its norm boiling point so as to precipitate the titanium content, substantially as desc ibed,

As new article of manufacture, a compound consisting essentially of iivc molcculcs of i0", combined with not mare than thrcs molecules or" H 6, substantially as dcscribcd.

its a new artic's of manufacture, an amorphous powder cons sting Essentially of fitc mclcculss of EEO, combined with not more than two moloculss or" H 6, substantially as dcscribsd.

As a new article of manufacture, a hydrated titanium oxide containing not more than 3% 80,, substantially as described 4 V V 39. As a new article of manufacture, a

pigment for paints consisting-of an opaque amorphous powder consisting essentially of titanic oxide combined with water and subf stantially free from combined sulphuric acid, substantially as described.

40. As a new article of manufacture, a

pigment for paints consistingcssentially ofa hydrated-titanium oxide containing not more than 10% of water in combination, substantially as described.

In testimony whereof, I have hereunto set my hand. I