SE203689C1 - - Google Patents

Description

CLASS INTERNATIONEf.LSVENSK C22 b40 a: 53/00 PATENT AND REGISTRATION AGENCY Ans. 1156/1958 was filed on 6/2 1958 issued on 2/8 196 ARMOR RESEARCH FOUNDATION OF 'ILLINOIS INSTITUTE OF TECHNOLOGY, CHICAGO, ILL. United States of America to produce titanium Inventor: F V Schossberger Priority Begtird from February 8, 1957 (USA) The present invention relates to a method of producing titanium from titanium ores and other titanium-containing raw materials. The invention is more particularly directed to a process in which such a titanium-containing raw material is prepared from a titanium solution which is fed with gaseous chlorine, after which the solution is reacted with an alkali metal halide so that alkali metal halide titanium precipitates.

In recent years, the demand for titanium increased strongly due to the special properties of titanium and titanium alloys. Due to the relatively low density, the good corrosion resistance and high half-strength increase the titanium application range for each day. The Rade use of titanium has hitherto been considerably hindered by the fact that titanium is very black to produce technically and thus hotly priced. This low price has been an obstacle to the widespread use of the metal Wrap.

Many different processes have been proposed for the production of titanium. All of these processes, however, frail the basic Kroll process according to U.S. Pat. No. 2,205,854, essentially involving the reduction with magnesium of titanium tetrachloride in a homo-like container or Van Arkel's 'iodide process'. All of these prior processes are limited to the discontinuous production of titanium. The raw materials are introduced into a reactor, the treatment is genoniforised and the metal is then taken out of the reaction vessel. Due to local overheating, this extraction of the metal is in many cases time consuming and expensive. Although these procedures have been able to satisfy the previously limited demand for titanium, in view of current technological developments and the foreseeable increase in demand in the future, it is essential to provide a simple, relatively inexpensive and continuous method of producing titanium. The present invention is directed to the harp.

In the past, titanium has mainly been produced from titanium tetrahydride, which in turn has been extracted from concentrated, expensive rutile ore. It has been necessary to use rutile in view of the high cost of eliminating the contaminants which occur when using less concentrated ores. Although rutile can be used as a starting material for the present process, it is also possible to use cheaper titanium minerals, such as ilmenite, FeTiO3, ferrous titanium slag and other titanium-containing raw material for the extraction of pure metallic titanium. As will be apparent from the following, the process according to the present invention is joke only continuous but also cheaper with regard to the raw material used and the recovery.

The present invention is based on the fact that, above all, moist potassium chlorotitanate and in general other moist alkali chlorotitanates can be dried to a fine powder by treatment with gaseous chlorine, if they are heated to about 20-300 ° C. water or mother liquor, as Or present in the solid chlorate titanates. According to the process described in more detail below, after a dry alkali chlorotitanate has been obtained, it is possible to reduce it to metallic titanium, while salts are formed by other elements which are derived from the starting material. The metal obtained by reduction of such dry alkali metal chlorotitanate is fully usable for technical purposes and is at least as pure as the normal technical titanium metal which can be obtained at present.

An object of the present invention is to provide a continuous process for the production of titanium. According to the invention, technical grade titanium can be produced by reduction of dry potassium chlorotitanate and in general also other dry alkali chlorotitanates with an alkali metal as reducing agent under much less demanding conditions regarding temperature and pressure than has been possible before. The invention is characterized in that the alkali halo titanate at 20 DEG-300 DEG C. is dried with dry chlorine and then reduced in an inert atmosphere or vacuum with alkali metal in solid phase to form metallic titanium and other end products, which are separated from the titanium.

The process of the present invention thus comprises two main tempos, namely first recovery of dry alkali chlorotitanates from titanium-containing feedstock and as a second rate reduction of such alkali chlorotitanates to titanium. During the first tempo, the raw material is dissolved in an acidic solution, converted to halide, precipitated and dried. During the second tempo, the reduction of the chlorotitanate and separation of the end products is carried out.

Titanium ores and other titanium-containing feedstocks can, as is well known, be digested in sulfuric acid or mixtures of sulfuric acid and hydrochloric acid as a first strut in the recovery of titanium compounds from such feedstocks. Following this digestion, the novel agents of the present invention can be used to recover pure titanium metal.

The invention can essentially be practiced with all kinds of titanium solutions. Since the preparation of such solutions is made from the production of titanium dioxide pigments, it will only be explained in more detail below such factors, which are necessary in order to understand the present invention. Although a complete procedure is described below, only those details which are considered to be new will be considered in more detail.

For a more detailed explanation of the present invention, reference is made to the following example: Ilmenite ore is first ground so that it can pass through a No. 250 sieve, after which the powder is mixed with sulfuric acid, 66 ° Be. The mixture of ilmenite and acid is rapidly heated to about 80-120 ° C. This heating triggers an exothermic reaction, which heats the temperature within the above range, until the reaction product solidifies or bakes together. The solidified mass is then leached with either dilute sulfuric acid or a mixture of sulfuric acid and hydrochloric acid. Such an acid mixture can be obtained by feeding acid effluents from other struts in the process. During leaching Midas an acidic solution of titanium and iron compounds, also containing insoluble, suspended material, which is easily separated from the solution by filtration or the like.

It is necessary to remove the iron from the solution. About 70% of the iron present is crystallized in the form of ferrous sulphate by cooling the solution to a temperature at which the ferrous sulphate crystals precipitate. This precipitation usually occurs at about 5-15 ° C. The crystals are then separated from the solution.

The next step is to carpet the now partially leveled solution with gaseous chlorine mat. This takes place at a low temperature, suitably -10 - -20 ° C, because at this temperature almost any remaining jam is precipitated in the form of ferric chloride, which is then separated from the remaining titanium solution.

Solid potassium chloride was then added to the cooled titanium solution, whereby potassium chlorotitanate precipitated. This Mining took place at about 0 ° C or slightly higher temperature than that at which the ferric chloride precipitated. About 95% of the titanium present in the solution has now been converted to solid potassium chlorotitanate. This is filtered off and the precipitate is dissolved in hydrochloric acid at room temperature. Subsequent cooling of the solution and addition of gaseous hydrogen chloride resulted in recrystallization and precipitation of the potassium chlorotitanate.

This recrystallization is not absolutely necessary in the process of the present invention but only in the preferred embodiment thereof. One can amen to other procedures, e.g. washing with acid, for railing of the chlorotitanate crystals. The recrystallization, however, achieves sufficient purity for most purposes. This recrystallization of the alkali chlorotitanate makes the material particularly suitable for filtration and subsequent drying, since larger crystals are obtained from the hydrochloric acid solution after the first precipitation of the salt from the mixture of sulfuric acid and hydrochloric acid. The recrystallization and purification of the crystals are absolutely essential in the process of the invention. Without these treatments, however, titanium is obtained from storage.

The precipitate is then centrifuged to separate the frail liquid. The product thus obtained contains about 2-3% moisture in the form of concentrated hydrochloric acid. If this moisture is allowed to remain in and around the potassium chlorotitanate crystals, the net yield of titanium is significantly reduced and the quality of the product formed is reduced.

The next step in the method according to the invention consists in removing this moisture without hydrolysis of the titanium compound. It has been found that this relatively firmly bound mother liquor can be deposited efficiently and completely by passing a stream of dry, gaseous chlorine water through the partially dried alkali chlorotitanate at a temperature of about 20-300 ° C. a solid product with a water content of 0.01%.

The hydrochloric acid required for various steps in the process of the invention can be recovered, recycled and reused, which is very important from an economic point of view.

The quantitative recovery of dry potassium chlorotitanate is illustrated by the following example: 362 parts of ilmenite, containing 50.0% of TiO 2, mixed with 724 parts of sulfuric acid 66 ° Be and the mixture is heated rapidly to about 95 ° C, until the mass solidifies. The mass is then leached with sulfuric acid to give a titanium solution of 133 g of iron per liter. When cooling this solution to 5 ° C, 79% of the dissolved jam precipitates in the form of ferrous sulphate. After filtration, the solution, shaved per liter, contains the following: Titanium100 g H2SO4440 g Jam.28 g By further cooling the solution to -17 ° C with subsequent maturation of the same with gaseous chlorine, most of the remaining jam precipitates as ferrochloride. After this jam was removed, 290.4 parts of solid potassium chloride was added to the solution to form small particles of solid potassium chlorotitanate. This is separated from the mother liquor by centrifugation. The wet solid product is then dissolved in concentrated hydrochloric acid at 30 ° C. Large crystals of K2T1C16 are precipitated by matting the hydrochloric acid solution with gaseous chlorovalue, while the solution is kept at 55 --- 15 ° C. The recrystallized material is centrifuged and then dried in a rotary kiln yid 220 ° C for 3 h in an atmosphere of gaseous chlorine. After this treatment, 660 parts of dry potassium chlorotitanate are obtained.

Potassium chlorotitanate should never before have been able to be dried to usable dryness without becoming unusable for the further treatment according to the present invention. According to the present invention, conducting physical precipitation to remove physically and chemically bound water and other oxidic substances from alkali chlorotitanates has resulted in various types of hydrated titanium oxides. The discovery that the treatment of potassium chlorotitanate with dry chlorine hydrogen gas can effectively remove virtually all of the water originally contained in the chlorotitanate forms the basis of the present invention. The thus prepared, dry potassium chlorotitanate is then reduced to the free metal.

The reduction of the present invention proceeds according to the following equation: A2 TiCl4 + 4M - -> Ti + 2 A Cl + 4 M Cl heat in which M represents an alkali metal, such as sodium, which acts as a reducing agent, while A represents an alkali metal radical.

In the reduction of the potassium chlorotitanate to titanium, it has been found that it is very important to mix it intimately with the reducing agent, since the reactive surfaces of the ram materials must be such that the reduction is easily introduced. For this reason, powdered alkali chlorotitanate and finely ground reduction metal are preferred. Although the exact grain size is not of the utmost importance, the ram types of granular reagents should have a high relative surface area to volume. At present, a grain size of about 1-10 is preferred. Good results are obtained, as the two reagents have approximately the same grain size.

It has been found that briquetting or pelletizing the reduction mixture, even if not absolutely necessary, impedes the handling of the material during the reduction and also saves an end product, which in many cases is better than just granules. The mixture of chlorolithanate and reducing agent can be compressed to form shaped bodies of various types, the shape depending on the apparatus available for carrying out the reduction and the apparatus used to convert the ratite to a suitable shape for the final treatment. After the reduction, the metallic titanium has essentially the same physical shape as the pressed shaped bodies.

If the reduction is carried out with briquettes, the entrapment of air in the briquettes must be prevented. Air entrapments trigger various side reactions, which adversely affect the formation of titanium. The oxygen in the air can thus react with sodium to form various sodium oxide compounds, which of course do not constitute any useful reducing agents, or the oxygen can react directly with the titanium, when it is formed, so that titanium metal is sprayed. Since the titanium metal can also react with the suffocation in the air, it should be obvious that the air inclusions can give rise to various by-products in the reaction. The air thus not only increases the cost 4 of the process by increasing the required amount of reducing agent but can also, more importantly, reduce the purity of the titanium. The formation of compounds of titanium and nitrogen as well as titanium and oxygen must be prevented as much as possible.

It must be mentioned, at least in passing, that even if briquettes or pellets are not used and the reduction is not limited to, for example, granular sodium and granular alkali chlorotitanate, the effect of the air must still be prevented. After the dry alkali chlorotitanate is prepared, it can be stored in an inert atmosphere and then reduced in such. The briquettes of reducing agent and alkali chlorotitanate should thus be formed in an atmosphere of an inert gas. For this andamai, the briquettes are most easily formed in a press in one. sadan atmosphere. The molds in the press can then be enclosed in a container with argon or lilac, or the powder mixture can also be placed in a separate, aerated, flexible container, from which the air has been expelled by purging with argon, after which the briquette is formed, while the powder remains in the container. Of course, it is also possible to produce briquettes in vacuum. Of the conceivable alternatives, however, this is probably the most expensive in terms of equipment and handling. However, if the manufacturer has access to a vacuum equipment, it may be more advantageous to enclose the vacuum press vacuum tools due to the affinity of the titanium for gases normally present in the atmosphere, and since many of these gases retain or completely magnify the adverse properties of the metal, as mentioned above. It is essential that the reduction according to the present invention is carried out either in a vacuum or in an inert atmosphere, for example helium or argon. At present, it is preferred to work in partial gas.

Once the material has been placed in the atmosphere of inert gas, the reduction can begin. A small excess, up to 15%, of reducing agent in the ratio tilt the stoichiometrically required amount can be used to ensure complete reduction. The reducing agent may be lithium, sodium, potassium, rubidium or cesium. According to the present example, however, sodium was used as the reducing agent. The reduction proceeds according to the following formula: K2 Ti G16 + 4 Na> Ti + 2 KCl + 4 Na Cl heat During the reduction, KCl and NaCl are formed in the form of occluded crystals. How these salts are deposited to obtain purified, usable titanium is set forth below.

The mixture of potassium chlorotitanate and metallic sodium is heated to about 325-600 ° C in the above-mentioned atmosphere of inert gas. The time required for the reduction depends to some extent on the temperature used. At a temperature of about 500 ° C, approximately 3 hours are required for the reduction to be completed. The time and temperature required can be easily determined experimentally in the individual case depending on the desired rate of formation and the available apparatus.

When the reduction is complete, the titanium contains salts, which have formed during the reaction. Although these by-products can be deposited in different ways, it is most convenient to leach with dilute hydrochloric acid. It is also possible to remove the final products formed in the reaction from the metallic titanium by vacuum distillation, which treatment is known in the art.

The following examples illustrate the reduction according to the invention.

Example 1. 339 g of anhydrous K 2 TiCl 4 are intimately mixed in an inert atmosphere with 101 g of metallic sodium, after which the mass is formed into briquettes with a piston press operating in an inert atmosphere. The briquettes are introduced into an oven and kept in an argon atmosphere for 4 hours at 500 ° C. The resulting mixture of titanium powder and potassium and sodium chloride is separated by washing with water, after which the titanium powder is thoroughly dried.

Example 2. 339 g of anhydrous K 2 TiCl 4 are intimately mixed under an atmosphere of dry argon with 30 g of metallic lithium, after which the mass is formed into briquettes by means of a piston press, operating in a shielding gas consisting of dry argon. The briquettes are kept in such an argon atmosphere for 4 hours at 500 ° C. The resulting mixture of titanium powder, potassium chloride and lithium chloride is separated by washing with water. The titanium powder is then carefully dried.

The present invention can be easily applied in the continuous production of titanium. After the second or first precipitation and subsequent separation from the mother liquor, the moist chlorotitanate is introduced into an atmosphere of chlorine water. The dried material is then mixed with crude reducing agents and formed into briquettes. These are then passed through the heating chamber in which the reduction takes place. The briquettes are continuously fed into a belt at one end of the reduction chamber, while the reduced briquettes are obtained at the opposite end of the belt.

It is obvious to the person skilled in the art that the set according to the invention entailed comfortable work at low temperature. Although the reduction can take place at a temperature of 325-600 ° C, it is not essential to operate at the higher temperatures of this range.

Although it is not essential to carry out the reduction of the material in briquetted form, this constitutes an exemplary embodiment of the invention.

Chlorine titanates of other alkali metals, such as sodium, rubidium and cesium, can also be used for reduction to titanium. These other chlorine titanates are dried with chlorine tea, and the method according to the invention is carried out on. the same sd.tt as in the reduction of potassium chlorotitanate.

As has been pointed out above, it is to be understood that liquid alkali metal chlorotitanates can be dried almost completely by heating in an atmosphere of chlorine gas, of paramount importance to the invention. It is known from British Pat. Nos. 645,152, 651,729 and 652,286 to produce titanium oxide pigments by applying the first aura steps of the process described above. However, these patents do not specify the method of removing moisture from alkali chloride titanate, since this moisture is obviously of no importance in pigment production. In the present invention, on the other hand, the moisture has a very detrimental effect on the net yield of titanium and the physical properties of the titanium, for which reason drying is important, as stated above. These three British patents illustrate the use of a solution obtained by acid digestion of titanium ore and subsequent filming of the halogen titanates. The processes described in the patents do not extend any further and do not contain any information on the production of metallic titanium.

U.S. Pat. No. 1,437,984 discloses a process for the production of refractory metals, mainly zirconium, although titanium is also mentioned. The patent discloses the use of volatile salts, for example RT2ZrF6, of the metal to be reduced, (which salts do not melt or volatilize markedly on any salt at the reaction temperature) together with a volatile metal, so as to obtain a product which is non-volatile or non-sublimable yid reaction temperature (see page 1, lines 66-73). According to a proposed reaction, K 2 ZrF 6 and sodium yid 315-370 ° C were used, the sodium being melted at 340 ° C. The patent does not mention any other solid salts, such as titanium salts.

It is thus obvious that this American patent specification refers to the use of a reaction which involves the use of a narrow metal as a reducing agent and a solid, volatile salt of a refractory metal. The reaction of the present invention, on the other hand, proceeds between an extremely volatile salt and a solid or liquid alkali metal. The reaction of the present invention implies the decided part of the process, that the starting materials and the end products are all solid and that a much lower reaction temperature can be applied. This Idgre reaction temperature entailed a particularly important technical advantage.

The embodiments described above can be modified without (Tailor exceeding the scope of the invention).

Claims (9)

Patent claim: 1. Said to produce titanium from titanium-containing feedstock in which a titanium solution of the titanium-containing feedstock is prepared and fed - Read with gaseous chlorine tea, after which the solution is pre-salted with an alkali halide, since alkali halo titanate is precipitated. dried with dry chlorine tea and then reduced in an inert atmosphere or vacuum with solid phase alkali metal to form metallic titanium and other end products, which are separated from the titanium. 2. A claim according to claim 1, characterized in that the titanium solution is continued with alkali chloride, since alkali chlorotitanate is precipitated. Salt according to claim 1 or 2, for the preparation of titanium from ilmenite, can be characterized in that the ilmenite is digested with sulfuric acid or a mixture of sulfuric acid and hydrochloric acid, and that the acidic titanium solution after maturation with gaseous chlorine tea is continued with potassium chloride. . 4. According to one of the claims in the claims 13, there is a claim that the precipitated alkali chlorotitanate is dissolved and resurfaced before it is dried. 5. A method according to claims 3 and 4, characterized in that the precipitated potassium chlorotitanate is dissolved in hydrochloric acid and Mlles by treatment of the solution with chlorine tea before it is dried. 6. According to claim 5, it is claimed that the drying of the moist potassium chlorotitanate is carried out at 20-300 ° C, after which the titanate is mixed with metallic sodium in inert gas and the mixture is heated to 3-6000 ° C in inert gas to reduce the chlorotitanate to titanium. and other reaction products, which are separated from the frau. titanium. Salt according to any one of claims 16, characterized in that the precipitated alkali chlorotitanate is dissolved and recrystallized and 6 is mechanically dried, so that part of the water is removed before drying with chlorine. 8. A kit according to claim 6, characterized in that the mixture of the dried potassium chlorotitanate and finely ground alkali metal is formed into pellets or pellets in an inert atmosphere. 9. A claim according to claim 8, characterized in that the dried potassium chlorotitanate is reduced with lithium, sodium, potassium, rubidium or cesium. Request publications: Gmelin's Handbuch der inorganchen Chemie. 8 completely new bearb. Aufl. System number 41. Titanium. Weinheim / Bergstrasse 1951, pp. 121. 397, 399, 401.