METHOD OF PRODUCING TITANIUM FROM TITANIUM OXIDES THROUGH MAGNESIUM VAPOUR REDUCTION

Abstract

Disclosed herein is a novel approach to the chemical synthesis of titanium metal from a titanium oxide source material. In the approach described herein, a titanium oxide source is reacted with Mg vapour to extract a pure Ti metal. The method disclosed herein is more scalable, cheaper, faster, and safer than prior art methods.

Claims

1. A method of producing titanium metal from titanium oxides comprising: a. providing a composition comprising a titanium oxide source in a reaction vessel; b. providing a composition comprising a Mg source in the reaction vessel; c. heating the reaction vessel to an internal temperature of between 850 C. and 1000 C. until a vapour of Mg is produced for at least 30 minutes to form a reaction product; and d. washing said reaction product with one or more washing media to form a washed titanium reaction product.

2. The method of claim 1 wherein the composition comprising a titanium oxide source comprises titanium oxide powder.

3. The method of claim 1 wherein the composition comprising a titanium oxide source comprises a natural rutile source.

4. The method of claim 1 wherein the composition comprising a titanium oxide source comprises an iron removed ilmenite sand.

5. The method of claim 2 wherein the titanium oxide powder comprises TiO.sub.2 nanopowder.

6. The method of claim 2 wherein the titanium oxide powder is a sub-oxide of Ti.

7. The method of claim 2 wherein the titanium oxide powder comprises 95% titanium oxide.

8. The method of claim 1 wherein the composition comprising the Mg source comprises Mg powder.

9. The method of claim 8 wherein the Mg powder comprises Mg nanopowder.

10. The method of claim 8 wherein the Mg powder comprises 99% Mg.

11. The method of claim 1 wherein the washed titanium reaction product has a purity of greater than 99% titanium.

12. The method of claim 1 wherein the reaction vessel is heated to an internal temperature of between 850 C. and 1000 C. for about 2 hours to form a reaction product.

13. The method of claim 1 wherein the reaction vessel is heated to an internal temperature of about 850 C. for about 2 hours to form a reaction product.

14. The method of claim 1 wherein the one or more washing media are selected from the group consisting of HCl, HNO.sub.3, H.sub.2SO.sub.4 and deionized water.

15. The method of claim 1 wherein the method further comprises providing inert gas in said reaction vessel.

16. The method of claim 15 wherein said inert gas is argon.

17. The method of claim 1 wherein the reaction vessel contains a first tray upon which the titanium oxide source is placed and a second tray upon which the Mg source is placed.

18. The method of claim 17 wherein one or both of the first tray and second tray are vibrated while the reaction vessel is heated.

19. The method of claim 1 wherein the reaction vessel further comprises a rotating drum and wherein the titanium oxide source is placed in the rotating drum and wherein the Mg source comprises Mg vapour and wherein the Mg vapour is purged into the rotating drum.

20. A method of producing titanium-iron alloy from ilmenite comprising: a. providing a composition comprising ilmenite source in a reaction vessel; b. providing a composition comprising a Mg source in the reaction vessel; c. heating the reaction vessel to an internal temperature of between 850 C. and 1000 C. until a vapour of Mg is produced for at least 30 minutes to form a reaction product; d. washing said reaction product with one or more washing media.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a schematic illustration of the experimental set-up used for TiO.sub.2 reduction process

[0018] FIG. 2 is a process flow diagram of the Ti extraction process

[0019] FIG. 3 is a powder X-ray diffraction pattern of TiO.sub.2

[0020] FIG. 4 is a powder X-ray diffraction patterns of the products obtained after the reduction of TiO.sub.2 with Mg prior to leaching with dilute HCl

[0021] FIG. 5 is a powder X-ray diffraction pattern of the product obtained after the reduction of TiO.sub.2 with Mg followed by leaching with dilute HCl

[0022] FIG. 6 shows SEM images of the products obtained when TiO.sub.2 is reacted with Mg vapour (a) before leaching and (b) after leaching with dilute HCl

[0023] FIG. 7 shows powder X-ray diffraction patterns of the products obtained when the TiO.sub.2 reduction process is performed at the following temperatures: (a) 700 C. (b) 800 C. (c) 850 C. and (d) 900 C. before leaching with dilute HCl

[0024] FIG. 8 shows powder X-ray diffraction patterns of the products obtained when the TiO.sub.2 reduction process is performed at the following temperatures: (a) 700 C. (b) 800 C. (c) 850 C. and (d) 900 C. after leaching with dilute HCl

[0025] FIG. 9 shows powder X-ray diffraction patterns of the products obtained when the TiO.sub.2 reduction process is performed with the following TiO.sub.2 to Mg molar ratios: (a) 1:1 (b) 1:2 (c) 1:3 and (d) 1:4, at 850 C. for 2 h before leaching with dilute HCl

[0026] FIG. 10 shows powder X-ray diffraction patterns of the products obtained when the TiO.sub.2 reduction process is performed with the following TiO.sub.2 to Mg molar ratios: (a) 1:1 (b) 1:2 (c) 1:3 and (d) 1:4, at 850 C. for 2 h after leaching with dilute HCl

[0027] FIG. 11 shows powder X-ray diffraction patterns of the products obtained when the TiO.sub.2 reduction process is performed at a reaction time of 0.5 h (a) before leaching (b) after leaching, at 850 C. with 1:2 molar ratio of TiO.sub.2 to Mg

[0028] FIG. 12 shows powder X-ray diffraction patterns of the products obtained when the TiO.sub.2 reduction process is performed at a reaction time of 1 h (a) before leaching (b) after leaching, at 850 C. with 1:2 molar ratio of TiO.sub.2 to Mg

[0029] FIG. 13 shows powder X-ray diffraction patterns of TiO.sub.2 reduction products obtained by leaching with dilute HCl acid under sonication (a) before leaching (b) after leaching

[0030] FIG. 14 shows transmission electron microscopy images of TiO.sub.2 reacted with Mg vapour (a) before leaching with dilute HCl acid at low resolution, (b) before leaching with dilute HCl acid at high resolution, and (c) after leaching with dilute HCl at high resolution.

[0031] FIG. 15 shows electron energy loss spectroscopy results of TiO.sub.2 reacted with Mg vapour (a) before leaching with dilute HCl showing Ti and O peaks, (b) before leaching with dilute HCl showing Mg peaks, and (c) after leaching with dilute HCl showing only Ti peaks

[0032] FIG. 16 shows energy dispersive X-ray diffraction results of TiO.sub.2 reacted with Mg vapour (a) before leaching with dilute HCl acid showing Ti in the core of the particle and Mg and O as a coating around the Ti core, (b) TiO.sub.2 reacted with Mg vapour after leaching with dilute HCl acid showing Ti and an oxidized layer of oxygen around the Ti.

DETAILED DESCRIPTION

[0033] The following description provides detailed embodiments of various implementations of the invention described herein. After reading this description, it will become apparent to one skilled in the art how to implement the invention in various alternative embodiments and alternative applications. However, although various embodiments of the present invention will be described herein, it is understood that these embodiments are presented by way of example only, and not limitation. As such, the detailed description of various alternative embodiments should not be construed to limit the scope or the breadth of the invention.

[0034] With reference to FIGS. 1 and 2, in an embodiment, a bed of 2.00 g of 99% pure TiO.sub.2 powder (obtained from Sigma Aldrich) is loaded onto a stainless steel (SS) tray which is suspended over a bed of 3.00 g of 99% pure Mg powder (Mg was used in excess) loaded on a separate SS tray. (See, e.g., FIG. 1). These trays are placed in a SS reaction chamber, which is sealed with a lid. The rim of the sealed container is covered by a ceramic paste to further seal the chamber. This reaction chamber is then placed in a furnace and, in some embodiments, the sealed chamber is filled with argon gas (e.g., as shown in FIG. 1). The reaction chamber is then heated to 850 C. The reaction is carried out for 2 h, during which time the vapour pressure of Mg is 4.6410.sup.3 Pa. Afterwards, the reaction chamber is cooled to room temperature. The resulting product is leached overnight with dilute HCl (1 M, 100 mL) to remove the magnesium oxide. Next, the product is rinsed with distilled water to remove the acid residues and dried at 50 C. An embodiment of this process flow is summarized in FIG. 2.

[0035] In still other embodiments, the reaction process described above is repeated at different temperatures, titanium oxide:Mg reactant molar ratios, and reaction times. In an embodiment, the reaction vessel comprises a rotating drum into which Mg vapour is purged.

[0036] Finally, in some other embodiments, ultrasound sonication was used to aid the washing process in order to improve the removal of MgO from the product. For example, in some embodiments ultrasound sonication was used for 2-5 minutes to aid in the washing process.

Characterization of Titanium Metal

[0037] The effects of reaction parameters such as temperature, reaction time, and reactant molar ratios on the nature and purity of the final product were investigated as described herein with reference to various figures.

[0038] FIG. 3 is the powder X-ray diffraction (PXRD) pattern for pure TiO.sub.2. The PXRD patterns of the product obtained when TiO.sub.2 is reduced with Mg (850 C., 2 h, argon environment but before leaching with dilute HCl clearly showed peaks related to Ti metal and as well as MgO (FIG. 4). Only Ti peaks were observed after the product was leached with dilute HCl indicating that the MgO had been completely removed (FIG. 5). Furthermore, there were no residual TiO.sub.2 peaks observed and there was no formation of any other titanium sub-oxides.

[0039] Table 1 (a) is the elemental analysis data based on energy dispersive X-ray spectroscopy (EDX data) of the product before leaching in dilute HCl acid. The EDX data before leaching confirms that there is a high percentage of MgO with a 35.12 wt % of magnesium and 28.16 wt % of oxygen and a low percentage of Ti of 36.72 wt %.

TABLE-US-00001 TABLE 1(a) EDX data after the reaction of TiO.sub.2 with Mg (prior to leaching in acid) Element Net Net Counts Weight % Line Counts Error Weight % Error Atom % O K 23879 +/625 28.16 +/0.36 33.33 Mg K 117867 +/1098 35.12 +/0.16 36.42 Ti K 33747 +/539 36.72 +/0.29 19.51 Total 100.00 100.00
The EDX data of the product after leaching shown in table 1 (b) indicates titanium with a high percentage of 99.37 wt % and a low oxygen percentage of 0.63 wt %. The oxygen detected may be due to the formation of an oxide layer over the Ti metal.

TABLE-US-00002 TABLE 1(b) EDX data after the reaction of TiO.sub.2 with Mg (after leaching in acid) Element Net Net Counts Weight % Line Counts Error Weight % Error Atom % O K 397 +/126 0.63 +/0.09 1.83 Ti K 350246 +/1903 99.37 +/0.27 98.17 Total 100.00 100.00

[0040] FIG. 6 at (a) shows an SEM image of the product before leaching with dilute HCl acid. The morphology of the product before leaching shows a plate like formation which is mainly due to the presence of crystalline MgO. FIG. 6 at (b) shows an SEM image of the product after leaching in acid. In this image Ti particles are observed, and the particle size of the product has been reduced after leaching when compared with the image taken before leaching. This indicates that MgO was produced as a layer over the produced Ti particles, and that layer has been washed away through the acid leaching step.

[0041] FIG. 7 shows the PXRD patterns obtained for the products received by varying the temperature of the Mg reduction process from 700 C., 800 C., 850 C., and 900 C. FIG. 8 shows the PXRD patterns after removing Mg impurities by washing with dilute HCl acid. As observed by the PXRD patterns the reaction carried out at 700 C. has led to an incomplete conversion into Ti metal. As shown by the patterns for both figures there is a significant amount of starting materials left in the sample for the reaction carried out at 700 C. According to the PXRD patterns at all other temperatures (800 C., 850 C., and 900 C.) a complete reduction of TiO.sub.2 into Ti metal has occurred.

[0042] The amount of Mg required was tested at different molar ratio of reactants (TiO.sub.2 to Mg powder) at 850 C., for 2 h. As shown in FIGS. 9 and 10, at the ratio of TiO.sub.2 to Mg 1:1, Ti peaks were observed with some unreacted TiO.sub.2 The observations suggest that the optimum molar ratio of TiO.sub.2:Mg is 1:2 for complete conversion of TiO.sub.2 to Ti metal. At higher molar ratios a significant amount of tightly bound Mg remained in the product, which was difficult to remove with simple acid washing steps.

[0043] FIGS. 11 and 12 show the PXRD patterns of products related to reactions carried out for different times at 850 C. with 1:2 molar ratio of reactants. In the embodiments shown, the reaction carried out for 0.5 h showed some unreacted TiO.sub.2. However the reaction carried for 1 h lead to formation of Ti metal without the presence of any sub-oxide peaks of Ti.

[0044] In another embodiment, the product obtained by the reduction of TiO.sub.2 with Mg (1:2 ratio, 2 h, 850 C.) was washed with a dilute HCl (100 mL) in the presence of ultrasound sonication (at an amplitude of 80, 3 minutes, two times). The PXRD patterns of the resulting product before and after leaching are given in FIG. 13.

[0045] Further structural studies obtained on a product from a preferred embodiment process (temperature 850 C., time 2 h, Mg:TiO.sub.2 molar ratio 2:1, ultrasound assisted dilute HCl washing) were carried out using transmission electron microscopic imaging (TEM), electron energy loss spectroscopy (EELS) and energy dispersive spectroscopy (EDX) spectral analysis and imaging. According to the TEM imaging (FIGS. 14 (a) and (b)) the product obtained after reacting TiO.sub.2 with Mg vapour results in a coshell product where the Ti particles are covered with MgO layer where there is a clear image contrast (area related to Ti metal appears darker than those of MgO). This observation suggests that lattice level interactions have occurred when the Mg vapour penetrates into the lattice of the TiO.sub.2. When the TiMgO product is washed with dilute HCl acid the image contrast no longer appears suggesting the complete removal of MgO.

[0046] According to the EELS results, Ti, O and Mg K-edge peaks at 455.5 eV, 532.0 eV, 1305.0 eV respectively, are observed in the TiMgO co-shell product. (FIG. 15 at (a) and (b)). When the product is leached with dilute HCl acid both O and Mg K-edge peaks disappear leaving only the Ti K-edge peaks. (FIG. 15 at (c))

[0047] MgO coated Ti crystals are clearly observed in the EDX elemental mapping image shown in FIG. 16 at (a) while any areas elated to Mg is not observed in the product received after leaching with dilute HCl acid (FIG. 16 at (b)). Only a very thin layer of oxide is formed on the Ti crystal accounting for the presence of 0.4% of oxygen in the EDX analysis.

[0048] The above description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles described herein can be applied to other embodiments without departing from the spirit or scope of the invention. Thus, it is to be understood that the description and drawings presented herein represent presently preferred embodiments of the invention and are therefore representative of the subject matter broadly contemplated by the present invention. It is further understood that the scope of the present invention fully encompasses other embodiments that may become obvious to those skilled in the art and that the scope of the present invention is accordingly limited by nothing other than the appended claims.