Patent Grant
8628736
This application is a 371 of PCT/IL2008/000889 filed Jun. 29, 2008, which claims the benefit of Israeli Patent Application Nos. 184311 filed on Jun. 28, 2007 and 192452 filed on Jun. 26, 2008, the contents of each of which are incorporated herein by reference.
The invention is directed to a process for the industrial production of titanium salts such as TiCl4, TiBr4, other titanium halide salts, titanium salts of mono-valent anions (TiX4), titanium salts of di-valent anions—TiX2 and titanium salts of tri-valent anions Ti3X4. In particular the present invention is directed to such a process without the addition of O2 and/or Cl2.
Titanium tetrachloride is typically produced by reacting titanium dioxide containing ore with chlorine in the presence of coke at a temperature of approximately 1000° C. in a fluidized bed reactor. The off-gas mainly contains the product TiCl4 gas, together with CO gas, CO2 gas and N2 gas. In the chlorination step ore and coke should be available in large amounts with respect to chlorine to ensure a complete reaction of chlorine.
The chlorination process results in the release of a variety of contaminates, such as CO, CO2 and other contaminates such as dioxins, into the atmosphere, which release must be prevented.
Titanium tetra halides can be produced by thermal conversion of titanium salts such as TiCl3, TiBr3 or TiOCl2. The raw materials for such production are expensive and are usually produced for titanium tetra halides themselves by reduction or hydrolysis:
TiCl4+H2═TiCl3
TiCl4+H2O═TiOCl2
TiCl4+O═TiOCl2
Titanyl chloride of high purity can be produced by carefully reacting TiCl4 with water. The cost of highly purified TiOCl2 is higher than that of TiCl4. As a result TiOCl2 is prohibitively expensive for the industrial production of TiCl4.
Titanic acid is usually used for the production of TiO2. It is produced in large amounts in the sulfate process. In this industrial production, the separation is done by heating a dilute solution at a relatively high temperature and in the presence of other contaminates. Since the resultant product was converted afterwards in the calcinations stage to TiO2, no attempt was made to produce it in a way in which it can be dissolved.
It was surprisingly discovered that titanic acid can be precipitated in such a way that the produced titanic acid is easily dissolved in acid to get concentrated titanyl salt solutions. In the sulfate process for example, titanic acid is precipitated from the solution obtained by the leaching of Ilmenite. It is precipitated from the above solution by heating a non-pure solution that results in a product with a purity that is much lower than needed for the production of TiCl4 and titanium metal.
The obtained product has a relatively low solubility in solution at low amount of acid halide (HX) solutions. As a result TiOCl2, TiOBr2, TiOl2 are not produced industrially via this route in order to produce titanium tetra halide and titanium metal.
It was very surprisingly found that an industrial process for the production of TiX4 can be achieved at a competitive production cost via an oxidative process. Such a process comprises the precipitation of titanic acid to produce titanic acid, dissolution of the titanic acid in acid solution and decomposition of a titanium salt at a temperature higher than 170° C.
The industrial process described in the present invention became feasible due to several discoveries and improvements that were made in the various stages of the process, which enabled the production of titanium salt at a purity level and cost required in the titanium industry, especially for the production of titanium metal.
It is an object of the present invention to provide a process for the production of TiCl4 and other titanium salts (TiX4) without the addition of Cl2 or O2, which process does not have the disadvantages of the release of undesired gases into the atmosphere.
The main use of the TiCl4 and other titanium salts produced, according to the present invention, is as a raw material for the titanium metal industry.
With this stage of the art in mind, there is now provided, according to the present invention, a method for the industrial production of titanium (IV) containing products TP by thermal conversion of titanium salts, said method comprising the steps of:
The method further includes the production of titanium metal from said titanium product TP during the thermal conversion stage of TP3. In addition, the method relates to the production of other titanium salts by the thermal conversion of TP3.
In the following, the term HX relates to a strong acid having a pK value lower than 2.5 and X relates to the anion of that acid and of the various titanium salts.
In one embodiment of the present invention, X is chloride and TP is TiCl4. In a preferred embodiment the anion X is selected from the group consisting of halides and monovalent anions (wherein TP is TiX4), divalent anions (wherein TP is TiX2) or trivalent anions (wherein TP is Ti3X4) and any combination thereof.
According to the present invention, the process is comprised of at least 3 stages:
In the following, the term titanic acid relates to TiO(OH)2, its hydrates (TiO(OH)2*(H2O)n or solvates (TiO(OH)2*(HX)n, (TiO(OH)2*(solvent)n, and also to any dehydrated or polymerized form of TiO(OH)2
According to the present invention, the main production of titanic acid is performed via the procedure that includes:
1. leaching of titanium containing ore;
2. Purification of the produced titanyl salt (TiOXn); and
3. Precipitation of titanic acid from said solution.
In a preferred embodiment of the present invention the titanyl salt TP1 is produced from a solution obtained by the leaching of Ilmenite or other titanium containing ores.
In order to produce TiCl4 and other TiX4 salts suitable for the production of titanium metal, its purity must be very high.
In a more preferred embodiment the titanyl salt TP1 is further purified to give a solution with a ratio between titanium to all polyvalent cations of higher than 97%.
In a more preferred embodiment the ratio between titanium to all polyvalent cations is higher than 99% and in a more preferred embodiment the ratio between titanium to all polyvalent cations is higher than 99.9%.
In a preferred embodiment the purification of the titanyl salt may be done using one or more conventional methods such as Extraction, Crystallization, and Separation upon ion exchangers or any other purification method.
In a more preferred embodiment the titanyl salt TP1 is further purified by the crystallization of its double salt. In a preferred embodiment of the present invention the double salt is selected from the group comprising of titanyl Monovalent-cation anions. In a preferred embodiment the titanyl double salt is titanyl ammonium sulfate. The precipitation of titanic acid from said double salt solution is done by adding a base to increase the pH.
In another preferred embodiment, the purification of the titanyl salt is done by it crystallization from the solution obtained after leaching. In a preferred embodiment, the crystallization is induced using a method selected from cooling, evaporation, addition of an anti solvent and the combination thereof.
In a preferred embodiment the anti solvent is an acid. In another preferred embodiment, the acid is H2SO4.
It was found that titanic acid dissolves more easily in acid solution at low temperature than from solution at higher temperature. In a preferred embodiment the titanic acid is precipitated from a solution at temperature lower than 90° C. In a more preferred embodiment the titanic acid is precipitated from a solution at temperature lower than 50° C., and in a more preferred embodiment the titanic acid is precipitated from a solution at temperature lower than 30° C.
In order to have a process for the industrial production of TiX4, the production cost should not be high.
In order to do so, a precipitation procedure for titanic acid was developed to yield easy dissolution of the titanic acid in HX solutions to produce the salt TP2 at high concentration
It was found that titanic acid that is precipitated by the addition of a base to the titanyl salt TP1 solution dissolves more easily if it the solution is well stirred and its solubility in acidic solution is better it is precipitated from a lower pH level solution than from higher pH level. Thus local high pH level in solution results in difficulties in the dissolution of the produced. It was also found that the presence of sulfate salts in solution can contribute to the production titanic acid with high solubility.
In a preferred embodiment the titanic acid is precipitated by adding a base solution to a well stirred solution. In a more preferred embodiment the titanic acid is precipitated from a buffered solution. In a more preferred embodiment the buffered solution contains a sulfate ion or other acidic buffers.
In a preferred embodiment, the concentration of the buffer solution is higher than 10%. In a more preferred embodiment, the concentration of the buffer solution is higher that 20%. In the best embodiment the concentration of the buffer solution is close to its saturation concentration.
In preferred embodiment the titanic acid is precipitated by adding a base solution at concentration lower than 3M to TP1 solution. In a more preferred embodiment, the base solution is at concentration lower than 1M and in a more preferred embodiment the concentration of the base is lower than 0.5M.
In a preferred embodiment the base solution is a solution comprising of ammonia. In a more preferred embodiment the base solution is a solution comprising of ammonia and ammonium salt.
It was found that the solubility of titanium salts in many solvents is surprisingly high. For example, the concentration of titanyl chloride in methanol solution is higher than 25%. Thus solubility of titanium salts in the various alkanols is high enough to enable the industrial use of such solvents for the dissolution of the titanium salts and the precipitation of dry titanic acid from such solutions. Among the solvents one may choose from the group of alkanols, hydrophilic solvents such as acetone, solvents that produce complexes with titanium such as TBP, DMF, formamide, DMSO and others. Extractants such as the amine extractants that extract both the anion and cation of the titanium salts (thus forming a couple extractant) and acidic extractants such as DEHPA and others.
In order to enable thermal conversion of the salt TP3 it should have very low water content. High water content will result in thermal precipitation of Titanium oxides and/or oxidation of reduced titanium salts used in the process.
In a preferred embodiment the titanic salt is precipitated from a titanium salt TP1 in solvent solution. In a more preferred embodiment the solvent in the titanic salt solution is selected from a group comprising of methanol, ethanol, propanol, butanol or other alkanols, DMSO, N-containing hydrophilic solvents such as DMF, methyl formamide, formamide Pyridine, pyramiding and their derivatives and the combination thereof. I another preferred embodiment the solvent in the titanic salt solution is selected from a group comprising basic extracts and acidic extractants. aln a preferred embodiment the titanic acid is precipitated from aqueous solution. In another preferred embodiment the titanic salt is precipitated from a water poor solution.
In a preferred embodiment, titanic acid is precipitated from a medium comprising of organic solvent.
It was found that removing water from the titanic acid prior to dissolving it in acid to produce the titanium containing product makes the next stages more simple and the production of the product TP becomes more feasible. Among the drying methods one may use washing the titanic acid with an hydrophilic solvent such as methanol or higher alkanol, extracting the water by passing a gas (such as air) over the product, using solid hygroscopic materials such as molecular sieve or drying under vacuum or any other drying method.
In another preferred embodiment, the titanium salt TP2 is dried after the dissolution of the titanic acid. Any drying method may be used.
In a preferred embodiment drying the titanic acid is done using method selected from washing with a solvent, contact with a gas, contact with a hygroscopic solid, contact with a concentrated solution or drying under vacuum or the combination thereof.
It was found that titanic acid can be dissolved in acidic solution to produce a titanium containing product TP2. For the purpose of producing titanium metal, the acid is selected from the group selected from acid halides and other acids with a pK value lower than 2.5 which are chemically stable at the conditions in which the reduction to titanium metal takes place.
In a preferred embodiment the titanic acid is dissolved in a solution containing a strong acid. In a more preferred embodiment the titanic acid is dissolved in a solution comprising of acid halide and in a more preferred embodiment the titanic acid is dissolved in HCl solution.
In a preferred embodiment the titanic acid is dissolved in aqueous solution. In a more preferred embodiment the titanic acid is dissolved in a solvent with low water content.
In a further more preferred embodiment the titanium containing product solution is dried to remove the water present in solution.
In another preferred embodiment, titanium containing product TP2 is crystallized to give a solid with low water content.
In another preferred embodiment, titanium containing product TP2 is crystallized to give a solid with low water content.
In another preferred embodiment, titanium containing product TP2 is crystallized to give a solid solvate wherein the solvate is selected from the group comprising of the acid HX or the solvent and the combination thereof.
In a more preferred embodiment TP2 is not solvated.
In a preferred embodiment the product TP2 is selected from a group comprising of titanium salts.
In a preferred embodiment the anion of the salt present in the salt TP2 is a mono valent anion. In a more preferred embodiment the anion of the salt TP2 is a halogen. In a more preferred embodiment the anion salt TP2 is Cl.
The Thermal Conversion Stage
Titanium salts TP3 that can be thermally converted to TP
1. The titanium salt TP2 among which are the titanyl halides TiOX2
2. Reduced titanium salts (such as TiCl3, TiCl2 TiBr3 and TiBr2)
3. Reduced oxo titanium salts (Such as TiOBr or TiOCl)
In a preferred embodiment the product TP is produced by a thermal decomposition of TiOX2. In this case, TP3 is the titanium salt TP2.
TiOX2═TiX4+TiO2 Eq. 1
In a preferred embodiment the thermal decomposition of TiOX2 is performed in medium comprising of TiOX2, HF, fluoride containing salt and the combination thereof.
In a preferred embodiment the product TP is produced by a thermal decomposition of TiX3
TiX3═TiX4+TiX2 T>350° C. Eq. 2
In a preferred embodiment the thermal conversion temperature is higher than 550° C. In a more preferred embodiment the temperature is higher than 600° C. In another embodiment the product TP is produced by a thermal.
In a preferred embodiment TiCl3 is reacted with TiO2 at temperature higher than 500° C. In amore preferred embodiment the reaction is performed at temperature higher than 650° C.
2TiX3+TiO2=2TiOX+TiX4 Eq.3
In a preferred embodiment TiCl3 is reacted with O2 at temperature higher than 500° C. In amore preferred embodiment the reaction is performed at temperature higher than 650° C.
3TiX3+1/2O2═TiOX+TiX4 Eq. 4
In a preferred embodiment TiX3 is reacted with HX at temperature higher than 250° C. In a more preferred embodiment the reaction is performed at temperature higher than 400° C.
TiX3+HX═TiX4+1/2H2 Eq. 5
In a preferred embodiment the product TP is produced by a thermal decomposition of TiX2 at temperature higher than 600° C. In a more preferred embodiment the reaction is performed at temperature higher than 700° C.
TiX2═TiX4+Ti Eq. 6
In a preferred embodiment the product TP is produced by a thermal rearrangement of
TiOX2+TiX3═TiX4+2TiOX Eq. 7
Conversion of Co-Products to TP3
1. Conversion of TiO2
In a preferred embodiment, the product TiO2 is converted to rutile at temperature higher than 600° C.
In a more preferred embodiment, the product TiO2 is converted to TP using a process comprising:
In a preferred embodiment, the product TiO2 is reacted with a divalent titanium salt TiX2 at temperature higher than 500° C.
TiO2+TiX2=2TiOX Eq. 7
TiOX+2HX═TiX3+H2O Eq. 9
In a preferred embodiment the reaction described in Eq. 8 is higher than 600° C.
In a more preferred embodiment, the product TiO2 is converted to TP using a process comprising of the steps
TiO2+2TiX3=2TiOX+TiX4 Eq. 10
TiOX+2HX═TiX3+H2O Eq. 9
In a preferred embodiment the thermal rearrangement is performed at temperature higher than 600° C. In a preferred embodiment the thermal rearrangement is performed at temperature higher than 650° C.
3TiOX═TiO2+TiX3 Eq. 11
In a preferred embodiment, the product TiCl2 is converted to TP using a process comprising the steps of:
TiX2+TiOX2═TiOX+TiCl3; Eq. 12
TiOX+HX═TiX3+H2O(gas); and Eq. 13
TiX3═TiX4+TiX2; Eq. 14
wherein the temperature in the step described in Eq. 12 is higher than 550° C.
Reduction of TP2
TiX4 can be reduced to Ti(III) using the various reducing agents. There was no indication in the scientific literature that the same can be done using the titanyl (TiOX2) salts as the raw material.
It was very surprisingly found that titanyl salts can be reduced using hydrogen to give TiOX (tested with Ti2OSO4 or Titanyl halogens such as TiOCl2). The reaction proceeds very well with hydrogenation catalysts even at room temperature in aqueous or in solvent solutions. If the reduction is done in a very acidic solution, TiX3 is produced instead of TiOX.
In a preferred embodiment Ti(IV) salt is reduced to Ti(III) salt. In a preferred embodiment the reduction is done in solution comprising of TiOX2, hydrogen and a hydrogenation catalyst and the combination thereof.
If TiOX is produced it can be converted to TiX3 by the addition of HX.
TiOXI2+H2═TiOX+HX Eq. 15
TiOX+2HX═TiX3 Eq. 16
In a preferred embodiment Ti(IV) salt is reduced to give a Ti(III) salt by adding a reducing agent to a medium comprising of Ti(IV) salt.
In a preferred embodiment TP2 is converted to the product TP via the following route:
4TiOX2+reductant (4e−)=4TiOX+reductant X4 Eq. 17
4TiOX+8HX═4TiX3+4H2O Eq. 18
The water is removed during second stage 2 or between the second and the third stages.
4TiX3=2TiX4+2TiX2 Thermal conversion Eq. 19
2TiX2═TiX4+Ti(0) Thermal conversion Eq. 20
Overall reaction 4TiOX2+8HX═3TiX4+1Ti(0)+4H2O+oxidized reductant.
In a preferred embodiment the anion X in Eq. 1—X is an anion, preferable a mono-valent anion, more preferable an anion selected from the group of halogens and the combination thereof and more preferable selected from the group composed of Cl or Br and the combination thereof.
In a preferred embodiment the reductant is H2 and the reduction is done with a catalyst.
In a preferred embodiment the reductant is a metal.
In a more preferred embodiment the reductant is selected from the group comprising of titanium, magnesium, Sodium, iron and the combination thereof.
In a preferred embodiment the reductant is selected from a group comprising of an inorganic or organic reducing agent compound or the combination thereof.
In a more preferred embodiment the reductant in Eq 17 is TiX2.
In a more preferred embodiment TP is produced in a process comprising the steps of:
2TiOX2+TiX2═TiOX+TiX3 Reduction Eq. 21
TiOX+TiX3+2HX═2TiX3+2H2O Acidulation to get Product TP3 Eq. 22
Titanyl salts produced from reacting titanic acid with acids and especially the titanyl halides contain a significant amount of water. Due to its hygroscopic nature it is very difficult to remove the water. The thermal conversion of titanyl salts usually lead to the reaction
TiOX2═TiO2+2HX. Eq. 25
Thus the thermal conversion product is TiO2.
It was surprisingly found that TiOX2 produced via the titanic acid route can be dried from water to such a level that it can be used for the thermal conversion reaction to form the TP product—TiX4.
In a preferred embodiment the anion in equations 1-25 is selected from the group comprising of Cl, Br, I and F and the combination thereof.
In a preferred embodiment the product TP in equations 1-25 is selected from the group comprising of TiCl4, TiBr4, TiI4 and TiF4 and the combination thereof.
While the invention will now be described in connection with certain preferred embodiments in the following examples so that aspects thereof may be more fully understood and appreciated, it is not intended to limit the invention to these particular embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the scope of the invention as defined by the appended claims. Thus, the following examples which include preferred embodiments will serve to illustrate the practice of this invention, it being understood that the particulars shown are by way of example and for purposes of illustrative discussion of preferred embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of formulation procedures as well as of the principles and conceptual aspects of the invention.
1 kg of 10% TiOSO4 solution and 4.5 kg of 5% NH3 solution were added into a vial. The suspension was filtered and washed with water. 1 kg of the wet cake was washed 3 times with ethyl acetate to remove the traces of water. 550 gr of the resulting homogenous suspension was added into a vial. 50 gr of gaseous HBr was added into the suspension while mixing for 2 hours. The precipitate (A) was filtered and dried.
10 gr of dry precipitate obtained in Experiment 1 were added into a beaker. N2 at 300° C. was flowing through the vial. The outlet gas was cooled to 20° C. and the liquid was analyzed and found to be TiCl4. The remaining solids were washed and analyzed. The solids were found to be TiCl2
10 gr of dry precipitate obtained in Experiment 1 were added into a beaker. N2 at 300° C. was flowing through the vial. The outlet gas was cooled to 20° C. and the liquid was analyzed and found to be TiCl4. The liquid and 0.2 gr of 0.5% Pd/carbon catalyst were introduced into a parr unit (high pressure mixed reactor). Gaseous Hydrogen was introduced for 4 hours at 120° C. and 20 atm for. The gas was released and cooled. The exiting gas contained HCl. 2.51 gr of purple solid (C), found to be TiCl3 remained in the parr. 2.51 gr of the remaining solid was heated (Under N2) to 500° C. Gas was released slowly and found to contain TiCl4. After 1 hour the parr unit was opened. The remaining solid (D) was analyzed and found to contain TiCl2. 1 gr of solid (D) was heated in a ceramic tube to 900° C. for 4 hours. TiCl4 was released and collected at 20° C. The tube was cooled and opened. The solid found in the tube was analyzed and found to be Ti metal.
1 kg of 10% TiOSO4 solution and 4.5 kg of 5% NH3 solution were added into a vial. The suspension was filtered and washed with water. 550 gr of the resulting cake was added into a vial. 50 gr of gaseous HCl was added into the suspension while mixing to obtain a clear solution. 200 gr of clear solution and 2 gr of Pd/carbon catalyst were introduced into a parr unit and mixed at 100° C. H2 gas was introduced for 3 hours. After 3 hours the temperature was raised to 120° C. and the gas was allowed to exit. The exiting gas contained water, HCl and H2. After 3 hours, the Parr was cooled and open. TiCl3 particles were found. The temperature in the parr is than increased to 500° C. The gas exiting the parr unit is cooled and found to be TiCl4. After 3 hours the parr unit is cooled and opened. Solid particles are present in the parr. The solid is found to be TiCl2.
10 gr of TiCl2 produced in the previous step is introduced into a ceramic tube. The tube is heated to 900° C. The gas exiting the tube is cooled and analyzed and is found to be TiCl4. After 3 hours, the tube is cooled to RT. Titanium metal is found in the tube.
1 kg of 10% TiOSO4 solution and 4.5 kg of 5% NH3 solution were added into a vial. The suspension was filtered and washed with water. 550 gr of the resulting cake was added into a vial. 60 gr of gaseous HBr was added into the suspension while mixing to get a clear solution. 200 gr of clear solution and 2 gr of Pd/carbon catalyst were introduced into a parr unit and mixed at 100° C. H2 gas was introduced for 3 hours. After 3 hours the temperature was raised to 120° C. and the gas was allowed to exit. The exiting gas contained water, HBr and H2. After 3 hours, the Parr was cooled and open. TiBr3 particles were found.
The temperature in the parr is than increased to 500° C. The gas exiting the parr unit is cooled and found to be TiBr4. After 3 hours the parr unit is cooled and opened. Solid particles are present in the parr. The solid is found to be TiBr2.
10 gr of TiBr2 produced in the previous step is introduced into a ceramic tube. The tube is heated to 900° C. The gas exiting the tube is cooled and analyzed and is found to be TiBr4. After 3 hours, the tube is cooled to RT. Titanium metal is found in the tube.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing examples and that the present invention may be embodied in other specific forms without departing from the essential attributes thereof, and it is therefore desired that the present embodiments and examples be considered in all respects as illustrative and not restrictive, reference being made to the appended claims, rather than to the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
| Number | Date | Country | Kind |
|---|---|---|---|
| 184311 | Jun 2007 | IL | national |
| 192452 | Jun 2008 | IL | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IL2008/000889 | 6/29/2008 | WO | 00 | 5/27/2010 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2009/001365 | 12/31/2008 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 2608464 | Aagaard et al. | Aug 1952 | A |
| 4112045 | Seko et al. | Sep 1978 | A |
| 5395497 | Bourgeois | Mar 1995 | A |
| 20060062722 | Liou | Mar 2006 | A1 |
| 20080015487 | Szamosfalvi et al. | Jan 2008 | A1 |
| 20090158895 | Vitner et al. | Jun 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 505183 | Dec 1952 | BE |
| 0005018 | Oct 1979 | EP |
| WO 2007043055 | Apr 2007 | WO |
| Entry |
|---|
| B.G. Newland, R.A.J. Shelton An effusion study of the disproportionation of titanium tri-iodide Mar. 1970 Journal of the less common metals vol. 20, Issue 3 pp. 245-249. |
| Number | Date | Country | |
|---|---|---|---|
| 20100257977 A1 | Oct 2010 | US |
