USRE15973E - Titanium compound and its manufacture - Google Patents

Description

Reissues] Dec. 23, 1924.

" UNITED STATES ram]; 1:. BACHIAN, or'ron'r nnimmunw You.

, .IITANIUI COMPOUND AND ITS MANUFACTURE.

I I I 1 J10 Drawing. Original application filed March 28, 1919, Serial 1%.. 285,878. Renewed September 4, 1m. Original No. 1,488,417, dated April 8, 1924. Application for reissue filed October 29, L924. Serial To all whomit may concern:

Be it known that I, FRANK E. BACHMAN, a citizen of the Unitedstates, residing at Port Henry, county of Essex, and State of 5 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 resemblin metatitanic acid.

duce a product of the character descri d economically. and in a substantially pure condition. v

In the following descriptionthe process is outlined beginning with the raw titanium bearing ore and ending with the final purified product, which 15 a soft impalpable opaque white powder which resembles metatItanic acid and titanium dioxide, but ap- 25. parently differs from metatitanic' acid in containm 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'sulphlirio acid, It is to be understood, however, that the process is not limited to the entire sequence of steps from the raw ore to the final prodnct, but' that a fewer number ofsteps may be employed. For example, the steps of purification of the titaniferous precipitate thrown down by boilin the titaniferous solution, may be emin purifying such titaniferous pre- .ployed cipitate' produced by other methods than thatconstitutin the 'reliminary steps hereingspecificall escri ed. Also some of the steps of puriingthe titanium compounds may-be omitted. v

The present invention is not limited to the final end product herein described and its preparation, but may be'employed in the production of the -so-called intermediate; products herein described, which of themselves are articles of manufacture and which may be considered as the final products in case their production is'desired T e object of the invention is to 10- it which when charred leave a'spon The process of'the present invention will be first outlined beginning with the raw material more, then the rocess and the products will be more speci call described. he raw material-rpreferab y used is ilmenite, either mined as such or obtained as a by-product from the concentration of titanium bearing 'ore, as, for example titanium bearing iron ores, vast deposits of which exist containing from 10 to 4;0% ilmenite, 25 to 80% magnetite and 5 to 50% gangue matter. An average composition of such ore is 36% ilmenite, 48% magnetite and 14% gangue matter.

The ore is crushed to pass a quarter inch mesh, and the product passed through magnetic separators, in which the greater part of the magnetite passes into the heads and the greater part of the ilmenite and ngue matter into the tails, the magnetite coming 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 jig' 'ng or tablin'g, whereby an ilmenite s ciently pure for my process is obtained at a low cost from a heretofore waste product.

approximate analysis of ilmenite so obtained has been 48.50% 'TiO ;.36.64:% F60; 6.04% Fe,o,; .es and; 3.70 Mgp; 2.17% SiO,; 2.17% undetermined.

he ilmenite is ground to a powder and mixedwith an excess-of carbonaceous mat,- ter. The carbonaceous matter is preferably a coking coal but other'darbonaceous matter such 'as sawdust,,coke, petroleum coke, and

anthracite may be used. When a car'- bon'ac'eous matter is used which does. not of itself coke, I prefer to add such materials I'BSldne. I have found that glutrin, a su tance 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 reto rts which are heated b external heat, the heat being preferablyo tained from th s produced by burnin in gas producersd'fi excess carbon which ad been mixed with former charges 10] to carbon monoxide and using such carbon monoxide by burnin it around the retorts. The heat so applied rives oil from the coal its volatile constituents in the form of gas which contains valuable by-products which ma be recovered. The carbon combines wit the oxygen of the iron oxides to form carbon monoxide which mixed with the combustible gas of the coal becomes available for heating, drying, etc., in. the subsequent steps of the process. The products of combustion used to heat the retort leave the retort furnace at a high temperature and may be used to raise steam or for other purposes. The carbon and iron oxides react apparently in accordance with the following equations: CgbFeO=Fe+ CO and 3C+Fe O :2Fe-} 3 The reaction leaves a spongy residue in the retort consisting essentially of metallic some ferrous sulphates and such small amounts of titanium sulphates as may have failed to decompose. he sulphuric acid reacts with the iron to form ferrous sulphate whic passes into solution leaving a. solid residu 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 titantium concentrate is then separated from the solution, digested with strong sulphuric acid, whereby the titanium dioxide is converted into titanic and titanous sulphates and the iron into ferrous sulphate. The titanic and titanous sulphates and the ferrous sulphatesare dissolved in water and then separated from tire 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- 'briquets when 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 contains in the form of ferrous sulphate the iron which was not dissolvedfrom the reaction product, to gether with such portions of the angue matter as were more readily solub e and any small quantity of the titanium sulphate which failed to decompose. Part of this solution is used to dissolve the iron contained in the reaction product as hereinbefore described. The. portion of the solution not so used,is concentrated, the free sulphuric acid recovered and the residue addedto 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 from the solution "and added to the titanium concentrate.

Referring now .to the impure precipitate of modified metatitanic acid which was thrown down by heating the acid solution made after treating the titanium concentrate with the strong sulphuric acids :-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 precipitate with dilute hydrochloric acid to dissolve and thereby removing the small amount of basic iron sulphates contained. The precipitate is then freed from the hydrochloric acid solution.

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 creamytint. This compound is apparently a modified metatitanic acid containing a small amount of combined 80,. Itdiifersfrom titanium dioxide in that it contains combined water, and from metatitanic acid in that it contains less combined water. This artially purified modified metatitanic acid may be used as an intermediate product, and still further purified to remove the decomposable combined s'ulphuric acid. When it is to be further puried, it is used damp as separated from the hydrochloric solution and further digested withla substance which has a stronger affinity for sulphuric acid than has basictitanic sulphate, to substantially free it from the remaining sulphuric acid compounds. There are many substances which ma be used for'this purification. I prefer, ow-' ever, to use a substance which is'soluble in water and whose resulting sulphates are also ,soluble,.such a subtance being for example an alkaline hydrate or carbonate. The resulting purified product is a compound resembllng metatitanic acid, which compound I term my modified metatitanic acid. 'It consists of titanic dioxide combined with some water, and free from iron and basic titanic sulphate. When this is heated tov a temperature sufiicient to expel a greater part of the combined waterbut not sufiicient to render 1t hard gritty, it becomes a soft amorphous exceedingly opaque product,

white or having a delicate cream tint, more suitable for pigments than titanium' dioxide products heretofore produced.

, The ferrous sulphate solution produced as n a byroduct is concentrated and' run into cryst lizing ans in which the ferrous sulphate crystallizes out of the mother liquor, and when separated from the mother liquor may be sol as the green vitriol of commerce) The mother liquor in? be treated if desired for the recovery magnesium sulphate by methods known to those skilled in this art. p

The process is described in detail as follows: i Y

Havin obtained the ilmenite it is ground so that or more-passes a-150 mesh sieve. It is then mixed with pulverized.

bituminous coking coal in the proportions of about 100 parts of ilmenite to parts ofcoal. No hard and fastirule can be iven for the proportions of ilmenite and coa owingto variable quality of, coals. The requirements are; to have enough coalto furnish an excess of carbon to reduce the iron oxides to metallic iron and an excess sufficient to make a coke strong enough to permit easy lixiviation of the product but not so dense as toprevent the acidsolution reachingv all parts of the lumps into intimate contact-with each particle of the ilmenite.

The, mixture of; pulverized coal vand llmenite is then charged into a retort. 1 For this purpose, I prefer a retort of the type used in the production ofiilluminating gas by the continuous process, wherein the coal is charged as the coke roduoed is withdrawn, the, coke being coo ed in an extension of the retort to 'below its ignition temperature. vThe heat for such a retort may be furnished' by the'combustion ofithe gas produced in/ a gas producer. I have used a retort heated electrically by resistance. coal andilmenite mixture is charged. as the reaction product is withdrawn, the with-- drawals beingso timed that the mixture remains in the heated zone ofthe retort for six hours or more. The bottom of the retort is sealedfa ainst ingress of air between withdrawals. he temperature within the retort 'is maintained approximately'at 1200 I C. during the operation. When the mixture comes'into' the heated zone the coal softens and ives off its volatile matter and when heate to about 750 (lthe reduction of the iron monoxide begins, metallic iron. forms and carbon monoxide gasis given off.

The reaction productas 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 product.

The

treated with a solution containing ferrous sulphate and almost free from free sulphuric aci and afterwards with solutions containing'less ferrous sulphate) and more free sulphuric acid. In practice I havev used five solutions in! thellixiviation of the reaction In the first four sulphuricacid was used and in the fifth water only, the wash water used in'the fifth 'stepbein used to dilute the acid solution used-m the ourth step. The acid solutions used-are those produced at a later step in, the process as a byproduct, bein the solutionsseparated from the crude mo ified metatitanic? acid preci i-' tate. Sufiicient water is added to these so utions to reduce the free sulphuric acid content to about a nine'or ten percent solution.

The contents of the lixiviating vessels is preferablykept at a temperature between and 80". centigrade. After washing with water the solid matterisi drained as free from water as possible: This solid matter forms my titanium concentrate. -An analysis on one occasion showed that" after drying at 100 centigrade itrhad approximately the followin composition :1

57% i0,; 8.5% vFe,'()"; il.4% A1 0,; 4% M ;.2% C80;22% 08Jb011;4% $10,; 1% v0 atile matter and water.

The solution contains the soluble iron as ferrous sulphate together with a little silica and magnesia, and m-the case analyzed also contained about 2.2% of the titanium dioxide charged in combination as titanous sul hate.

The, so ution also contains some 0 the titanium concentrate and the carbon in, suspension. To this solution is added the solid residueleft afterj concentratin and distilling' that portionof the sulphur c acid which is not used to treat the'concentrate. This solid residue consists-o5 ferrous sulphate with a small amount of ferric and titanic sulphate, together with such portions of the nguematter as passed into solution. The Idrric sulphate "{generallyv present in su fficienti'quantitieslto oxidizethe titanous sulphate in the iron solution to titanic sul hate,

and the; ferrous sulphate in su cient quantit'y'to-fully saturate the solution. The solutionyis'then-heated in am iron vessel to the whereupon the titanium content gquic precipitates as a crude metatitamc'jaci' Owing to, the presence of gelatinouegsilica which acts as an agglomerant," tlie'metatitanic acid, silica, carbon and undissolved '--'concentrate which have passed thro hlthe lixiviating vessel settle clear solution is run into crysta ing pans in:' which the ferrous sulphateds recovered. "In this way I recover .about of the iron contained in the ilmenite as green vitriol,. a valuable article of commerce. The \metatitanic 'acid is drained. The solution is ;added to the small phates. The mixture is gradually heated.

ferrous sulphate solution, the solid matter to the titanium concentrate.

Referring now to the titaniumconcentrate lined digester into which is also. run the. sulphuric acid drained. from the residue in w the second step to be described. The digester is a closed vessel contents may be stlrred. A cylindrical vessel hung on trunnions andhaving internal baflies 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 coning the digester." The heating at 200 to 225 centigradeis continued for about an hour,- after which the contents are allowed to cool to about. 100 ='centi'grade or f. .1ess,; and the wash water from the treatment 'ofaprevious-' batch by the second step, to befiihereafterdescribed, is added and the".stir.ring continued'meanwhile. The product so obtained is removed from the digester and drainedfree 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 approximately 1.3. It consists essentially of titanic sulphate and ferrous sulphate, together with quantities of magnesium and aluminumsu hate and silica. In some cases there is a sin 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 into solution in its ferrous state, and thereby saves the cost of later reducing ferric to ferrous iron. 7

The solid matter remainin after the first step just described, is furt er treated to recover the remaining titanium content. This solid residue while still damp and containing 30'to 40% ofwater, istransferred to an iron vessel to which is added sufli; cient-sulphuric acid to theoretically convert the iron, titanium, magnesium, and aluminum contained in the concentrate into sulwith occasional stirring to 200 centigr ade or over, which temperature is held for someinto 311 capable of resisting pressure and so arranged" that the;

.quent I atch of concentrate. tents reaches 165 to 175 centigradgwheres the excessive water: is expelled.v The} digester is left open up tothis point, then the digester is closed and the heatingcon-f tinned under pressure until thetemperature' of the contents'reaches 200 to 225{1centigrade. "Duringsthisheating thecontents of the digester is fsftirred, preferably by rock- V time, about one-half hour generally being suflicient. By'this means the greater part of the titanic dioxide andiron not converted into sulphates in thefirst step, are converted phates and pass into the solution, together with a portion of the magnesia and alumina. Some of the silicates are decomposed, the silica becoming gelatinous. The

acid is then drained from the solid matter, preferably on an asbestos suction filter. The sulphuric acid drained oil is used in the first step of digesting. the titanium concentrate. The solids are washed with water using about three and-'..one-half times by volume of the sulphuric acid used. This is the wash water which is to be added duringthe. first-step described to dissolve the sul hate formed by digesting a subse- The solid matter remaining is pressed (lamp into briquets and dried. After drying the briquets to about 3259 centigrade they were found by one analysis to have approximately the following composition: 5% volatile matter and water; fixed carbon; and 35% ash.

The ashwas about 8% by weight of the ilmenite and its composition was found to .be in the case analyzed about 38.5% SiO,

48% TiO,;,3.5% A1 0,; 8% F8 0. an

1.8% MgO. The ashe left after vburning the! briquets is a 'yellow brown powder,

slightly gritty, which when ground with a drying oil fdrms a paintespecially suitable for-application to metallic surfaces.

In the first. step is was found on one analysis that about 86% of the titanium content of the ilimenite passed into a solution,

and in the secondstep about 6%" a ssed into a solution, leaving about 8% un isolved in the residue. On other occasions I 'haveobtained as high as 96% of titanium in the solution, leavlng less than 4% in the residue;

Referring now to the sulphuric acid solution containing the titanium content digested from the titanium concentratezfIf this solution.contains-titanous sulphate in excess, the greater art or all of it is oxidized to titanic sulp ate, the titanic sulphate thus produced is normal titanic', sulphate having the formula T i(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. oxidizin chemicals on account of its lesser cost. If erric sulphate is present it is reduced t6 ferrous sul hate, preferably by electrolysis, carrying t e reduction to a point where traces of titanous sulphate show. A small quantity of sulphurous acid may be then added to be doubly .sure of preventing any of the ferrous phate precipitated in the next volume of hydrochloric acid. I find that theaddition of this small amount of hydrochloric acid tends to reduce the amount of basic iron sulphates and basic titanium sulstep in which the crude metatitanic acid is precipitated.

When heated to its normal perature 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.

I grade, but when,

titanium tion has been necessary in order The solution is then run into a lead veseel enclosed in a boiler containing a small uantity of water and heat is applied. en the air in the boiler is driven out by the steam, the boiler is closed and the heat continued until the pressure reaches about seventy pounds per square inch, corresponding to a tem erature of about 162 centi grade. The heat is then continued for a suflicient time to make sure that the solution is heated to this point. Then the heat is withdrawn and the vessel and contents allowed to cool to 100 centigrade or less.

The titanium recipitates' as my new titanium compoun 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 sulph-ate. I For example, a titanic sulphate solution of 1.3 specific gravity containing .0792 grams TiO and .0149 grams Fe per cubic centimeter was not completely decomposed when heated for two hours at 147 centia like solution was heated centigrade for thirty minutes, the was completely separated from the solution. A like solution diluted with water to 1.1 specific gravity was completely freed from T10, after heating for thirty minutes at 135 centigrade; .It is to be understood therefore, that the above temperature may varied to meet the conditions encountered. v

Heretofore it has been customary to dilute the sulphuric acid solution of the titanium .and afterwards to heat such dilute solution to its atmospheric boiling point. The dilu- 3 the precipitation to take place when so heated. The precipitate thus obtained by heating the dilute solution has been metatitanic acid. Inmy process instead of diluting the solution, "I ta e the solution as formed by the previously described steps, which solutioli' may have a specific gravity as high as 1.3, or. even as high as 1.42, and heat such solution in the closed ve sel above its atmgss boiling temto permit pheric boiling point to precipitate the titanium content. The heating above the atmospheric boiling point permits a more concentratedsolution 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 necesary under the former practice of using dilute solutions and heating them to the atmospheric 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 precipitated by heating the dilute solutions.

The titanium compound is then separated from the liquid by filtration or otherwise. The compound when dried forms a soft opa ue amorphous powder which is white or o a'creamy' tint when derived from solutions containing alarge proportion of iron. An anal sis of a typical sample of this compound owed it to contain .08% Fe,0,; SO 7.75% combined water and 89.59% 156,. y t .r'

When this titanium compound is dried at 100 0., it has a defimte composition rangingtbetween 84 to 94% TiO,,, 1 to 5% S0,, races to 2% F0 0,, and 4 to 10% H O. This new titanium compound produced maybe used as an article of manufacture, or it may be stillfurther purified as hereinafter described. Also v may be to purifymetatitanic acid or modified metatitanic acid produced by other processes, the steps of purification process not being dgpen'dent upon the specific process em loye for producing the metatitanic or mo ified metatitanic acid. a

Starting now with the modified metatitanic acid produced by the preceding process (or metatitanic acid produced byother 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% nature and the nitric acid is added to oxidize used. The sulferrous to ferric iron and to destroy any organic matter ifpresent. The solid matter is H then drained and washed with water until Qfied as hereinafter described.

I purification of metatitanic am the basic titanic This compound is distinguished from titanium dioxide in that it contains more combined water, less TiO, and more SO and is distinguished from metatitanic acid in that it contains more TiO and less combined water. My belief is that it is essentially modified metatitanic acid con-v taining 5-molecules of TiO combined with one molecule of H O,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 or 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 ma be applied to a modified metatitamc aci produced by steps other than those hereinbefore specifically described, or may be applied to the or to the purification of partially ignited metatitanic acid, that is metatitanic acid from which a portion but not all 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 mymodified metatitanic acid compound, produced by the foregoing steps, it is transferred to the digester while still damp. Enough water is added to bring the material to a paste. and then the substance that will combine with the sulphuric'acid exist in the modified metatitanic acid combined as basic titanic sulphate. The treatment now described transfers the- SO contained in sulphate to the base of the purifying substance used. I find that there are a number of-such purifying substancesLwhich may be used. For example, the alkaline hydrates, the more readily decomposable -acetates, metallic oxides and hydroxides, many of the carbonates, such as' those of sodium, potassium, lead, zinc calcium, etc., and the chlorides of the al-' "-kaline earths preferably in the presence of.

hydrochloric acid.

For the:product1on ofa white pigment I use only such of these substances as produce a soluble sulphate or a white insoluble sulphate. I find that certain ofthe subcontent is added. The sulphu.- -ric acid is believed to stances are more activethan 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'. I find that caustic soda is a satisfactory purifying substance to use 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 sul phate of the substance added, for example, to form Na SO when caustic soda is used. The digester is then closed and heat is applied until the temperature rcaches about seventy pounds per square inch, at which ressure it is held for about two hours, or which time the material is continuously agitated. While the above pressure and time is preferred,'no hard and fast rule can be given as necessary to complete the 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 andsoluble 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. I v tially when dried at 100 centigrade, of titanium compounds containing 5 molecules of TiO and 1 molecule of combined water, together with varying quantities of modified metatitanie-iacid containing more than 1 molecule of water. The impurities, if any,- are insignificant amounts of SiO,. A1 0,, Fe O ortho titanic acid, TiO,- and undecomposed basic titanic sulphate. It is a soft-amorphous opaque powder free from gritty substances and in color white or of a delicate creamy tint. y

It is distinguishable from metatitanicacid in that it contains less combined water and is distinguishable from pure titanic dioxide in that it contains combined wateryis freetothe heat and pressure believe that it consists essen-' '11'1 composition, a portion of it being so" cient for this.

: pl ments. v

' isms 3d investigations lead me to believe that the hasic titanic sulphate present in metatitanic acid, modified'm'etatitanic -acid ,,or partially ignited metatitanic acid,- is of varysta 1e that itdoes not decompose when mixed with drying oils'when applied as a paint, and another portion fbeing unstable The portion not removedb the aforesaid treatment, if any, is the-s'ta le ortion;

The compound may be ried at a tempera} 'ture of 100Q'centigrade and used as a pig- '-ment, or it may be heated to a temperature suflicient to'decom 0% the metatitanic acid, driving off its com inedwater but not sufii-' cient to render thetitatanium dioxidethus producedhard and gritty. V'A temperature] of between 550? to 600 centigrade i's-sufli- Referring now to the solution from which the modified metatitanic acid was separated by heating v In one typical case this solution was found to have a specific gravity of about 1.25; In addition to the diluting water used, it contains the sulphuric acid set free by the decomposition of thetitanium sulphate, the

excess of sulphuric acid used, the ferrous,

aluminum and magnesium sulphatesjproduced from the decomposition of the oxides of these elements present in the concentrate, any small amount. of titanium sulphate which was not decomposed in the treatment, and a small amount of silica. i

The solution not. used for dissolving the iron in the reaction product I concentrate in'lead pans to any desired strength. During the concentration thegreater portion of the ferrous sulphate, together 1 with some ferric sulphate produced by atm pheric oxidation, separate. The solution is rained into retorts and distilled. The sulphuric acid passing oil is condensed and made available for -further use. ,In previous methods for the production of titaniumdioxide, the sulphuric acid has been generally lost.. .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 distilla tion contains ferrous and ferricsulphate, the titanic sulphate which -failed to separatefrom the solution and the lgreat'eri art of the magnesium and aluminum su'phate's,

I 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'prooess hereinbefore described produces a purer article and one better adapted for use than processes heretofpre used. ,The general process hereto 2 fore used of making metatitanic acid has been tobring the titanium bearing materials into-hydrochloric or sulphuric acid solution,

then fleeing the'solution from excessive acid,

anducingany iron toferrousiron, diluting the solution until the titanium content doesnot exceed 1%, saturating the solution with a reducing chemical such as sulphurous acid, and boiling-the solution for suchtime as is necessary todecompose the titanic sulphate, the resulting product being, impure metatitanic 'acid,fa-soiidi and sulphuric acid in solution. A metati-tanic acid derived from sulphuric acid solutions isalw'ays' contaminated with basic titanic-sulphate and with basic ironrsulp'hatewhen iron, sulphate is present in the solution. 7 The proportion of these basic sulphates varies. Numerous analyses prove, however, that the S0,, presentreaches from 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, haslong been known as is noted in .A system of quantitative chemical analysis by Dr. C. Remigius Fresenius, John Wylie and Sons, New York, 1877, sec. 107 page 178. When this has been used in the p'reparation of titanium dioxide pigments itxhas been found that when -mixed with. drying :oils and applied with a paint,.the basic titanic sulphate gradually decomposes, settin free sulphuric acid, and

the sulphuric aci' Jintu'rn acts on the oil.

whereby the paint becomes discolored. It has been. proposed to drive'ofi' the S0 by heat. When metatitanic acid. containing this impurity is heated, it gives off the greater part of its combined water at a tempera'ture before 450 centigrade.

centigrade the basic sulphates begin to de compose, SO being volatilized and TiO re maining. The sulphates continue to be decomposed until the temperature reaches about 850centigrade, at which there is little or no further decomposition 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 amor hous powder to a hard gritty substance, re atively unsuited for use as a pigment. On the'other hand, I

when heated to a temperature. which is suflicient to remove relatively all of the combined water but not all of the $0 if ground 1 in oil, it will, if sufliciently free from iron, produce a paint which will be white when applied but graduall change color to a dirty yellow. This ciange in color I believe to be due to the action of the 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 igment is free from any gritty matter and as 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. beginning with the treatment "of. the titanium bearing ore to the final purification, it is to be understood that the process is not limited 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 the foregoing description, but may beotherwise employed within the scope of the following claims.

I claim:

1. Those steps of 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 the metallic state, treating the reaction .product thusobtained with an acid which dissolves the iron-leaving the titanium con tent in the residue, digesting the" residue with an acid of sufiicient strength to dissolve the titanium 'content and forming a solution 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 mixing an iron and titanium bearing material with carbonaceous material which when charred leaves a spongy residue. heating the mixture to reduce the 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 titanium content 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 sulphate, substanacid than basic titanium tially as described.

'stantially as described v 8. Those steps in the herein described hydrochloric acid. and thereafter treating it with a substance which has a greater affinity for sulphuric acid than basic titanium sulphate. substantially as described. I

5. That step in the herein described process of treating titaniferous materials, which consists in purifying a hydrated titanium oxide by treating it with. a substance which has a. greater affinity for sulphuric acid than basic titanium sulphate, substantially as described.

6. That step in the herein described process of treating titaniferous materials which consists in treating a titanium material having as an impurity atitanium sulphate with a substance which has suflicient aflinity for sulphuric acid to break up the titanium sulphate and combine with the sulphuric acid, substantially as described. v

7. Those steps in the herein described process of treating titaniferous materials which consist in forming an acid solution.

containing titanium and some iron impurities. heating the solution to precipitate the titanium content and treating the preci itate with dilute hydrochloric acid to disso ve the iron. contained in the precipitate. subprocess of treating titaniferous material which consist in forming an acid titaniferous solution, precipitating the titanium con-.

tent from such solution, and treating the precipitate with a substance which combines with such acid as may be combined with the precipitate, substantiall as described.

9. Those steps in t e herein described process of treating titanife'rous materials which consist in forming a sulphuric acid titaniferous solution, precipitating the titanium content from such solution, and treatin the precipitate with a substance which as 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 consistin 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, andthereafter 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 unafiected, sub

stantially 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 recipitate the titanium content as a modi ed metatitanic acid, substantially as described.

12. Thatstep in the herein described process of treating titaniferous materials which consists-in forming a titaniferous acid solution of such concentration that the titanium would not be precipitated b heating the solution to its atmospheric oiling point, and in heating s'uch solution under pressure to above its atmospheric boiling j precipitated to treat a freshbatch of thereactxon product, substantially as described.

gravity of at least 1.1-. under point so as to recipitate the titanium content, substantia ly 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 pressure to above its atmosphericboiling point so as to precipitate the titanium content, substantially as described. a

14. That step in the herein described process of treating titaniferous materials which consists in heating under pressure and to above its atmospheric boihng point a solution of titanium sulphate containing an excess of sulphuric acid sons to precipitate the titanium content as a hydrated titanium oxidefcontainingless combined water than metatitanic acid, substantially as described.

15. Those steps in the herein described process of treating titaniferous materials which consist in forming a solution of titanium containing an excess of free acid,

and then heating .thesolution under pressure and in such a manner as to precipitate 7 the titanium content, substantially as described. 1

16." Thom steps in the herein described process of treating tita-niferous materials which consist in formin a titaniferous reaction product containln metallic iron, treating such reaction p uct with acid to dissolve the iron, digesting the residue with acid to dissolve the titanium content, treating this solutiontoprecipitate the titanium content therefrom, and using the acid solution from which the titanium content was 17. Those steps in the herein described process of treatingtitaniferous materials which consist in forming a titaniferous reaction product containing-reduced metallic iron, treating this reaction product with sulphuric acid to dissolve the. reduced iron, (1' t' the residue with strong sulphuric acid to 'ssolve the titanium content, there,-

after so manipulating thistitaniferous solution as to precipitate the titanium content. therefrom, and using the waste sul huric 'acid solution from which the titaniferous content has been precipitated to treat afresh process of treating titaniferous materials which consists in digesting a fer'miginous titaniferous' material with strong sulphuric acid under heat and pressure in a closed vessel whereby the titanium content is dissolved and the iron content is dissolved as ferrous sulphate, substantially as described.

20. That ,step in the herein described process of treating titaniferous materials which consists in digesting a ferruginous titaniferous material with acid under heat and pressure in a closed vessel so as to dissolve the titanium content and also bring .the iron content into-solution in its ferrous state, substantially as described. I

21. These steps in the herein described process of treating titaniferous materials, which consist in mixing a titaniferousmaterial containing'iron oxides with a carbonaceous material, treating the mixture by heating it so as --to reduce the containing iron to. a metallic state butwi-thout changing the chemical combination of the titanium, and leaching the reaction roduct thusobtained with an acid which issolves the. iron but leaves the titanium content, substantially as described. a a

22. That step in the herein described process oftreating titaniferous materials which consistsin heating a solution of titanium sulphate containing free acid and substantially free from ferric salts to 'a' temperature above its normal boiling point sons to precipitate the titanium content, substantially as described.

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

i 24. That step in the herein described process of treating titaniferous materials, which consists in heating a titanium solution which contains some titanous sul hate to a temperature above its normal v iling point so as to precipitate the titanium content, sub- 1 stantiallyias described. 25. As a new article of manufacture, a

white amorphous powder consisting of asubstantially as described.

28. As a new article of manufacture, a hydrated titanium oxide containin .less than 10% of combined water and su stantially free from iron and combined sulphuric acid, substantially as described.

29. That step in the herein described proces of treating titaniferous materials which consists in forming a sulphuric acid titaniferous solution, precipitating the tita nium content from such solution, purifying the precipitate of combined sulphuric acid by treating it with a substance which has a greater affinity for sulphuric acid than basic titanium sulphate, and thereafter heating the purified precipitate to drive off the combined water, substantially as described.

30. That step in the herein described process of treating titaniferous material, which consists in heating a titanic sulphate solution above its normal boiling point so as to 'precipitate the titanium content, substantially as described.

31. That step in the herein described process of treating titaniferous material, which consi in heating a titanic sulphate solution containing some titanous sulphate to a' temperature above its normal boiling point so as to precipitate the titanium content, substantially as described.

32. Those steps in the herein described process of treating titaniferous materials,

which consist in adding a reducing agent to a titanic sulphate solution and then heating the 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 acid temperature to a temperature above its normal boiling point so as to precipitate the titanium content, substantially as described.

36. As a new article of manufacture, a titanium compound consisting essentially of five molecules of TiO combined with not more than three molecules of H 0, substantially as described.

37. As a new article of manufacture, an amorphous powder consisting essentially of five molecules of TiO combined with not more than two molecules of H 0, substantially as described.

38. As a. new article of manufacture, a hydrated titanium oxide containing not more than 3% S0,, substantially as described.

39. As a new article of manufacture, a piglment for paints consisting essentially of a ydrated-titanium oxide containing not more than 10% of water in combination, substantially as described.

40. As a new article of manufacture, a pigment for'paints consisting of an opaque amorphous white powder consisting essentially of five molecules of TiO combined with not more than three molecules of H 0 to form a hydrate, substantially as described.

In testimony whereof I have hereunto set my hand.

FRANK E. BACHMAN.