METHOD OF PRODUCING TITANIUM FROM TITANIUM OXIDES THOUROUGH MAGNESIUM VAPOUR REDUCTION

Abstract

Disclosed herein is a novel approach to the chemical synthesis of titanium metal from a titanium oxide source material, such as a mineral comprising titanium. In the approach described herein, a titanium oxide source is reacted with Mg vapor 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 a titanium comprising mineral, the method comprising: acid leaching the titanium comprising mineral; providing at least a portion of the acid-leached titanium comprising mineral in a reaction vessel; providing a composition comprising an Mg source in the reaction vessel; heating the reaction vessel to an internal temperature of between 850 C. and 1000 C. until a vapor of Mg is produced for at least 30 minutes to form a reaction product; and washing said reaction product with one or more washing media to form a washed titanium reaction product.

2. The method of claim 1 further comprising wet nano-grinding the titanium comprising mineral prior to acid leaching the titanium comprising mineral.

3. The method of claim 1, wherein the hydrothermal treatment comprises heating the mixture within a hydrothermal treatment vessel to a temperature between 250 C. and 500 C. for at least 2 hours to cause formation of a crystalline titanium compound.

4. The method of claim 3, wherein the hydrothermal treatment comprises heating the mixture within the hydrothermal treatment vessel to a temperature of approximately 300 C. for approximately four hours.

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

6. The method of claim 4 wherein the Mg powder comprises Mg nanopowder.

7. 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.

8. The method of claim 1 wherein the reaction vessel is heated to an internal temperature of about 900 C. for about 2 hours to form a reaction product.

9. 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.

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

11. The method of claim 10 wherein said inert gas is argon.

12. 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.

13. The method of claim 12 wherein one or both of the first tray and second tray are vibrated while the reaction vessel is heated.

14. The method of claim 1, further comprising: mixing the acid leached titanium comprising mineral with an aqueous solution of NaOH; and heating a mixture of the acid leached titanium comprising mineral and the aqueous solution of NaOH to extract a titanium comprising compound from the mixture using a hydrothermal treatment, wherein the titanium comprising compound is supplied to the reaction vessel.

15. The method of claim 14 wherein the mixture is contained within a hydrothermal treatment vessel during the hydrothermal treatment.

16. The method of claim 15, wherein the hydrothermal treatment vessel is a Teflon tube.

17. The method of claim 1 wherein ultrasound sonication was used during at least a portion of the washing of the reaction product with the one or more washing media.

18. The method of claim 17 wherein the ultrasound sonication was used for approximately 2-5 minutes during the washing of the reaction product with the one or more washing media.

19. The method of claim 17 wherein the ultrasound sonication was used for approximately 30 minutes during the washing of the reaction product with one or more washing media.

20. A method of producing titanium metal from rutile comprising: acid leaching the rutile to form an iron-leached out titanium comprising mineral; providing the iron-leached out titanium comprising mineral in a reaction vessel under inert conditions; providing a composition comprising Mg in the reaction vessel; heating the reaction vessel to an internal temperature of between 850 C. and 1000 C. until a vapor of Mg is produced for at least 30 minutes to form a reaction product; and washing said reaction product with one or more second washing media.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a schematic illustration of the experimental set-up used for TiO.sub.2 reduction process, according to an example embodiment;

[0022] FIG. 2 is a process flow diagram of the Ti extraction process, according to an example embodiment;

[0023] FIG. 2A provides a flowchart illustrating processes and procedures of an example embodiment of the Ti extraction process;

[0024] FIG. 3 is a powder X-ray diffraction pattern of TiO.sub.2;

[0025] 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 acid, according to an example embodiment;

[0026] 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 acid, according to an example embodiment;

[0027] FIG. 6 shows scanning electron microscopy images of the products obtained when TiO.sub.2 is reacted with Mg vapor (a) before leaching and (b) after leaching with dilute HCl acid, according to an example embodiment;

[0028] 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 acid, according to example embodiments;

[0029] 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 acid, according to example embodiments;

[0030] 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 acid, according to example embodiments;

[0031] 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 acid, according to example embodiments;

[0032] 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, according to an example embodiment;

[0033] 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, according to an example embodiment;

[0034] 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, according to an example embodiment;

[0035] FIG. 14 shows transmission electron microscopy images of TiO.sub.2 reacted with Mg vapor (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; according to an example embodiment;

[0036] FIG. 15 shows electron energy loss spectroscopy results of TiO.sub.2 reacted with Mg vapor (a) before leaching with dilute HCl showing Ti and O edges, (b) before leaching with dilute HCl showing Mg edges, and (c) after leaching with dilute HCl showing only Ti edges, according to an example embodiment;

[0037] FIG. 16 shows energy dispersive X-ray diffraction results of TiO.sub.2 reacted with Mg vapor (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 vapor after leaching with dilute HCl acid showing Ti and an oxidized layer of oxygen around the Ti, according to an example embodiment;

[0038] FIG. 17 provides a schematic diagram of the synthesis of Ti from natural rutile, according to an example embodiment;

[0039] FIG. 17A provides a flowchart illustrating processes and procedures of an example embodiment of the Ti extraction process with raw rutile as the Ti source;

[0040] FIG. 18 shows powder X-ray diffraction patterns of (a) synthetic rutile (TiO.sub.2), (b) natural rutile, (c) wet ground rutile and (d) wet ground and acid leached rutile, according to example embodiments;

[0041] FIG. 19 shows powder X-ray diffraction patterns of (a) as-synthesized sodium titanate and (b) sodium titanate after calcination, according to an example embodiment;

[0042] FIG. 20 shows scanning electron microscopy images of sodium titanate nano rods;

[0043] FIG. 21 shows powder X-ray diffraction patterns of the product (a) before leaching with acid and (b) after leaching with acid, according to an example embodiment;

[0044] FIG. 22 shows scanning electron microscopy images of the product (a) prior to leaching with acid and (b) after leaching with acid, according to an example embodiment;

[0045] FIG. 23 shows energy dispersive X-ray mapping of titanium sponge before leaching with acid, according to an example embodiment;

[0046] FIG. 24 shows energy dispersive X-ray mapping of titanium sponge after leaching with acid, according to an example embodiment;

[0047] FIG. 25 provides a flowchart illustrating processes and procedures of another example embodiment of the Ti extraction process with raw rutile as the Ti source;

[0048] FIG. 26 shows powder X-ray diffraction patterns of (a) synthetic rutile (TiO.sub.2), (b) natural rutile and (c) wet ground and acid leached rutile, according to an example embodiment;

[0049] FIG. 27 shows powder X-ray diffraction patterns of Ti sponge (a) before acid leaching and (b) after acid leaching, according to an example embodiment;

[0050] FIG. 28 shows scanning electron microscopy images of (a) natural rutile, (b) synthetic rutile and (c) ground and acid leached natural rutile, according to an example embodiment;

[0051] FIG. 29 shows scanning electron microscopy images of Ti sponge (a) before leaching with acid and (b) after leaching with acid, according to an example embodiment;

[0052] FIG. 30 shows energy dispersive X-ray diffraction results of Ti sponge before leaching with dilute HCl acid, wherein (a) shows the combined results for Ti, Mg, and O in the Ti sponge, (b) shows the results for Ti in the Ti sponge, (c) shows the results for Mg in the Ti sponge, and (d) shows the results for 0 in the Ti sponge, according to an example embodiment;

[0053] FIG. 31 shows energy dispersive X-ray diffraction results of Ti sponge after leaching with dilute HCl acid, according to an example embodiment; and

[0054] FIG. 32 shows electron energy loss spectroscopy results of titanium sponge (a) before leaching with dilute HCl acid showing Ti, O and Mg edges and (b) after leaching with dilute HCl acid showing only Ti edges, according to an example embodiment.

DETAILED DESCRIPTION

[0055] 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. As used herein, the term approximately refers to values that are within manufacturing and/or engineering standards and/or tolerances.

[0056] An Example Process of Reducing TiO.sub.2

[0057] With reference to FIGS. 1, 2, and 2A in an example embodiment, a bed of approximately 3.00 g of >99% pure Mg powder 110 is loaded on a first non-corrosive (e.g., stainless steel) tray 108 and placed in a reaction chamber 112 (at block 202). A bed of 2.00 g of 99% pure TiO.sub.2 powder 106 (e.g., obtained from Sigma Aldrich) is loaded onto a separate second non-corrosive (e.g., stainless steel (SS)) tray 108 which is suspended over the bed of Mg powder 110 (at block 204). (See, e.g., FIG. 1). In an example embodiment, Mg is used in excess. These non-corrosive trays 108 are placed in a non-corrosive reaction chamber 112. In an example embodiment, the non-corrosive reaction chamber 112 is then sealed with a lid 104 (at block 206). In an example embodiment, the rim of the sealed container is covered by a ceramic paste 114 to further seal the chamber 112. In an example embodiment, the reaction chamber and/or the lid is made, at least in part, of stainless steel.

[0058] In various embodiments, the sealed reaction chamber 112 with the first and second non-corrosive trays 108 sealed therein is placed in a furnace. In an example embodiment, the sealed chamber 112 is filled with an inert gas (e.g., as shown in FIG. 1), such as, for example, argon. The inert gas is provided to the interior of the sealed chamber 112 via the inert gas inlet 102 (at block 208). In an example embodiment, the inert gas is continuously purged (e.g., inert gas is continuously provided via the inert gas inlet 102 and removed via the inert gas outlet (not shown)). In an example embodiment, the inert gas is provided into the sealed reaction chamber 112 prior to heating of the reaction chamber 112 and removed after the heating of the reaction chamber 112. In an example embodiment, the inert gas may be purged from the interior of the sealed reaction chamber 112 and the reaction chamber 112 may be refilled a predetermined and/or configurable number of times during the heating of the reaction chamber 112. The sealed reaction chamber 112, is then heated to approximately 850 C. (at block 210). The reaction is carried out for approximately 2 h, during which time the vapor pressure of Mg is approximately 4.6410.sup.3 Pa.

[0059] Afterwards, the reaction chamber 112 is cooled to room temperature (e.g., approximately 18-30 C.) (at block 212). In an example embodiment, the reaction chamber 112 is actively cooled and in another embodiment, the reaction chamber 112 is passively cooled. The resulting product is leached overnight and/or for approximately 8-12 h with dilute HCl acid (1 M, 100 mL) to remove the MgO (at block 214). Next, the product is rinsed with distilled water to remove the acid residues and dried at approximately 50 C. (at block 216). An embodiment of this process flow is summarized in FIG. 2.

[0060] In some embodiments, the reaction process described above is repeated at different temperatures, TiO.sub.2:Mg reactant molar ratios, and reaction times. In an embodiment, the reaction vessel comprises a rotating drum into which Mg vapor is purged.

[0061] In some embodiments, ultrasound sonication is used to aid the washing and/or rinsing process in order to improve the removal of MgO from the product. For example, in some embodiments ultrasound sonication was used for approximately 2-5 min to aid in the washing and/or drying process. In an example embodiment, the first and/or second tray 108 is vibrated using, for example, ultrasound sonication and/or mechanical vibration means, during at least a portion of the washing and/or drying process.

Characterization of Titanium Sponge

[0062] 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.

[0063] 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 acid clearly showed peaks related to Ti and as well as MgO, as shown in FIG. 4. Only Ti peaks were observed after the product was leached with dilute HCl, as shown in FIG. 5, indicating that the MgO had been completely removed. Furthermore, there were no residual TiO.sub.2 peaks observed and there was no formation of any other titanium sub-oxides.

[0064] 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 Mg and 28.16 wt % of O 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 HCl acid) Element Net Net Counts Weight % Line Counts Error Weight % Error Atom % O 23879 +/625 28.16 +/0.36 33.33 Mg 117867 +/1098 35.12 +/0.16 36.42 Ti 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 Ti 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 397 +/126 0.63 +/0.09 1.83 Ti 350246 +/1903 99.37 +/0.27 98.17 Total 100.00 100.00

[0065] FIG. 6 at (a) shows a scanning electron microscopy (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 HCl acid and washing and/or rinsing with distilled water. 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 thorough the acid leaching and/or washing and/or rinsing with distilled water step(s).

[0066] 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 and washing and/or rinsing with distilled water. As observed by the PXRD patterns the reactions carried out at 700 C. and 800 C. have led to an incomplete conversion into Ti metal. As shown by the patterns for FIG. 8 there are a significant amount of starting materials left in the sample for the reactions carried out at 700 C. and 800 C. According to the PXRD patterns at all other temperatures (850 C. and 900 C.) a complete reduction of TiO.sub.2 into Ti metal has occurred.

[0067] 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 of 1:1, Ti peaks were observed with another set of peaks which is related to 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. 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.

[0068] 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 (TiO.sub.2 to Mg). In the embodiments shown, the reaction carried out for 0.5 h showed some unreacted TiO.sub.2 as shown in FIG. 11. However the reaction carried for 1 h lead to formation of Ti metal without the presence of any suboxide peaks of Ti as shown in FIG. 12.

[0069] 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 frequency of 80 kHz, 3 min, two times). The PXRD patterns of the resulting product before and after leaching are given in FIG. 13 at (a) and (b) respectively.

[0070] Further structural studies obtained on a product from a preferred embodiment process (temperature 850 C., time 2 h, TiO.sub.2:Mg molar ratio 1:2, 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 (Fig. at 14 (a) and (b)) the product obtained after reacting TiO.sub.2 with Mg vapor results in a co-shell 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 vapor 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.

[0071] According to the EELS results, Ti, O, and Mg K-edges at 455.5 eV, 532.0 eV, and 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-edges disappear leaving only the Ti K-edges. (FIG. 15 at (c))

[0072] MgO coated Ti crystals are clearly observed in the EDX elemental mapping image shown in FIG. 16 at (a) while areas related to Mg are 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 approximately 0.4% of oxygen in the EDX analysis.

[0073] An Example Process of Extracting Ti from Raw Rutile

[0074] Ilmenite (FeTiO.sub.3), rutile (TiO.sub.2), and leucoxene are the only naturally-occurring Ti bearing minerals that have been considered as suitable feedstock for either the Ti metal-producing or pigment industries. This is because only these minerals are found in large enough commercial concentrations; compared with other naturally occurring minerals comprising Ti.

[0075] The occurrence of mineral sands was first discovered in Sri Lanka mainly in the northeast coast of Pulmuddai in 1904. The minerals found in sand are ilmenite, rutile, zircon, Hi Ti ilmenite, monazite and garnet, which are all mixed in with ordinary sea sand (e.g., quartz). These minerals have uses in many industries ranging from paint pigment manufacture, paper, plastics, porcelain ware, aerospace and many others. Amongst these minerals, rutile shows the second largest commercial production as 9,000 tons per year according to the data reported by Lanka Mineral Sand Limited.

[0076] Even though, the annual production of rutile is less than that of ilmenite (90,000 tons per year), it is still important to develop a method to extract Ti from rutile, as it shows high percentage of TiO.sub.2 (96%) compared to the percentage of TiO.sub.2 in ilmenite (54%).

[0077] In the process of extracting Ti described above, which may be used for example to extract Ti from ilmenite sand, it was confirmed that structural iron present in ilmenite should be removed prior to carrying out the reduction process with Mg to obtain a Ti sponge. Although, the percentage of structural Fe in rutile sand is significantly lower than that of ilmenite, direct reduction of rutile with Mg was not possible. Therefore, this study mainly focuses on development of methods to extract Ti as a sponge from rutile as the raw material.

[0078] An Exemplary Process

[0079] FIGS. 17 and 17A provide a flow diagram and a flowchart of an example process of extracting a Ti from a mineral and/or ore comprising Ti, such as, for example, raw and/or natural rutile, according to an example embodiment. In various embodiments, the mineral and/or ore comprising Ti is wet ground. In an example embodiment, natural rutile (e.g., approximately 10.0 g) was mixed with of distilled water (e.g., approximately 20 ml) and wet ground for 1 h (at block 302). In an example embodiment, the rutile and distilled water is wet ground using a FRITSCH planetary ball mill using 1 mm Zr balls. In an example embodiment, the wet ground mineral and/or ore is acid leached to remove iron impurities. For example, the ground rutile (10.0 g) is acid leached overnight (e.g., for approximately 8-15 h) with concentrated HCl (e.g., approximately 10 mL) to remove iron impurities (at block 304). The product is rinsed with distilled water to remove acid residues and dried at 50 C., for example. Samples were characterized using PXRD (Bruker D8 Focus) with Cu K (=0.154 nm) irradiation at a scan rate of 0.02 s.sup.1 and a 2 range of 5-90 and SEM (Hitachi SU 6000600) with accelerating voltages of 5-20 kV and EDX (Hitachi SU 6000600) with accelerating voltages of 20 kV (see, for example, FIG. 18).

[0080] In an example embodiment, at least a portion of the rutile (e.g., approximately 2.0 g) obtained by wet grinding, is mixed with 10 M NaOH (e.g., approximately 30 ml) solution to form a mixture and/or solution comprising Ti. For example, the acid leached, wet ground mineral and/or ore comprising Ti is mixed with a NaOH solution or other solution to form a mixture and/or solution comprising Ti. In an example embodiment, the solution used to form the mixture and/or solution comprising Ti is a basic solution. The mixture and/or solution comprising Ti is placed in a hydrothermal treatment vessel, such as, for example, a Teflon tube (at block 306). The mixture and/or solution comprising Ti mixture is then introduced to hydrothermal treatment by heating at approximately 300 C. for approximately 4 h under autogenous pressure (at block 308). The resulting product is cooled down to room temperature (e.g., approximately 18-30 C.). The resulting product may be actively or passively cooled in various embodiments. The cooled resulting product is washed with distilled water (e.g., 50 ml, three times) to remove base residues and then is dried at approximately 50 C. (at block 310). In an example embodiment, the product resulting from the hydrothermal treatment is sodium titanate. In various other embodiments, the product resulting from the hydrothermal treatment may vary based on the contents of the basic solution used to form the mixture and/or solution comprising Ti. In an example embodiment, the product resulting from the hydrothermal treatment is a crystalline and/or nanocrystal product, such as, for example, crystalline sodium titanate (e.g., sodium titanate nano rods).

[0081] In an example embodiment, the product resulting from the hydrothermal treatment is loaded onto a second non-corrosive tray 108. In an example, embodiment, the product resulting from the hydrothermal treatment is ground to form a powder and then loaded onto a second non-corrosive tray 108. For example, crystalline sodium titanate may be ground to form a powder and then loaded onto a second non-corrosive tray 108. In an example embodiment, nano crystals (e.g., sodium titanate nano rods) resulting from the hydrothermal treatment may be loaded onto a second non-corrosive tray 108. For example, a bed of approximately 2.0 g of sodium titanate was loaded onto a second non-corrosive tray 108 (e.g., a stainless steel tray) which was suspended over a bed of approximately 5.0 g of Mg powder loaded on a first non-corrosive tray 108 (e.g., a stainless steel tray). In an example embodiment, the Mg powder is used in excess. The trays 108 of sodium titanate and Mg power are placed in a non-corrosive reaction chamber 112 that is then sealed with a lid 104. In an example embodiment, the rim of the sealed container 112 was covered by a ceramic paste 114 to further seal the chamber. The sealed reaction chamber 112 was placed in a furnace and the chamber was saturated and/or filled with inert gas (e.g., Argon gas) via the inert gas inlet 102. In an example embodiment, the sealed reaction chamber 112 is heated to approximately 950 C. within the furnace (at block 312). The reaction is continued for approximately 2 h in an example embodiment. After the reaction has been continued for approximately 2 h, the inert gas is removed from the sealed reaction chamber 112 via an inert gas outlet (not shown) and the reaction chamber 112 is actively and/or passively cooled to room temperature (e.g., approximately 18-30 C.). In an example embodiment, the resulting product is leached overnight with dilute HCl (e.g., 1 M, 100 ml) to remove MgO (at block 314). The product is rinsed with distilled water to remove the acid residues and dried, for example, at approximately 50 C. For example, the reduction process may be similar to that described above with respect to FIGS. 2 and 2A.

[0082] FIG. 18 shows PXRD patterns of (a) synthetic rutile (TiO.sub.2), (b) natural rutile, (c) wet ground rutile and (d) wet ground and acid leached rutile. The PXRD patterns of synthetic rutile, natural rutile, wet ground rutile and wet ground rutile after acid leaching are shown in FIG. 2. As shown in FIG. 2(b), the raw rutile does not show all the characteristic peaks related to synthetic rutile. However, it was observed that there is a tendency of relevant peaks to appear with the treatments, suggesting that structural change of natural rutile to synthetic rutile occurs with the removal of iron impurities during the grinding and acid treatment (FIG. 2(d)).

[0083] FIG. 19 shows PXRD patterns of (a) as-synthesized sodium titanate and (b) sodium titanate after calcination. As shown in FIG. 19(a), the sodium titanate is in the amorphous form. In order to confirm the structure, the product was subjected to calcination. The PXRD pattern of the calcined product was matched with the crystalline structure of sodium titanate (Na.sub.2Ti.sub.3O.sub.7). The absence of other peaks confirms that all the rutile has been converted into sodium titanate.

[0084] FIG. 20 shows SEM images of sodium titanate nano rods. The SEM image of the sodium titanate shows rod like nano structures with the diameter less than 100 nm. PXRD pattern of Ti sponge before and after leaching with diluted HCl is shown in FIG. 21 at (a) and (b) respectively. The absence of peaks related to MgO in the PXRD diffractogram of acid leached Ti sponge (FIG. 21(b)) confirms the complete removal of MgO from the product as MgCl.sub.2 (MgO (s)+Ti (s)+2HCl (aq).fwdarw.Ti (s)+MgCl.sub.2 (aq)+H.sub.2O (l)). Further, the absence of any peak related either to TiO.sub.2 or sodium titanate confirms that the intermediate product (sodium titanate) has been successfully reduced to Ti during the reduction with Mg vapor.

[0085] FIG. 22 shows SEM images of the product (a) prior to leaching with HCl acid, (b) after leaching with HCl acid. FIG. 23 shows EDX mapping of Ti sponge before leaching with HCl acid. FIG. 24 shows EDX mapping of Ti sponge after leaching with HCl acid. The morphology of the product before leaching, as shown at FIG. 22 (a), shows a rod like structure with the deposition of MgO crystals on the surface of the rods. It is further confirmed by the EDX mapping of the Ti sponge before acid leaching (see FIG. 23). FIG. 22 (b) is representative of the pure nano sized Ti sponge. Further, the particle size of the product has reduced after leaching compared to the image taken before leaching. This indicates that MgO was produced as a layer over the produced Ti rods and has been washed away thorough the acid leaching step. The EDX mapping data of the acid leached Ti sponge (FIG. 24) further supports the conclusion as there are no other elements present as impurities other than some residual Fe, resulting in an average purity of 99% Ti in the sponge.

[0086] Extraction of 99% Ti from Sri Lankan rutile sand was successfully achieved by hydrothermal extraction of rutile followed by Mg vapor reduction technique as described herein.

[0087] Another Exemplary Process

[0088] FIG. 25 provides a flowchart of another example process of extracting Ti from a mineral and/or ore comprising Ti, such as, for example, raw and/or natural rutile, according to an example embodiment. In an example embodiment, rutile sand is obtained (e.g., from Sri Lanka mineral sand Ltd, Sri Lanka) and a 37% HCl acid (Sigma-Aldrich analytical grade) may be used to wash the sand as initial step. In various embodiments, no further purifications are required prior to the process described herein.

[0089] In various embodiments, the mineral and/or ore comprising Ti is wet ground. In an example embodiment, natural rutile (e.g., approximately 10.0 g) was mixed with of distilled water (e.g., approximately 20 ml) and wet ground for 1 h (at block 402). In an example embodiment, the rutile and distilled water is wet ground using a FRITSCH planetary ball mill using 1 mm Zr balls. In an example embodiment, the wet ground mineral and/or ore is acid leached to remove iron impurities. For example, the ground rutile (10.0 g) is acid leached overnight (e.g., for approximately 8-15 h) with concentrated HCl (e.g., approximately 10 mL) to remove iron impurities (at block 404). The product is rinsed with distilled water to remove acid residues and dried at 50 C., for example (at block 406). Samples were characterized using powder X-ray diffractometer (Bruker D8 Focus) with Cu K (=0.154 nm) irradiation at a scan rate of 0.02 s.sup.1 and a 20 range of 5-90 and scanning electron microscopy (SEM, Hitachi SU 6000600), with accelerating voltages of 5-20 kV and energy dispersive X-ray spectrometer (EDX Hitachi SU 6000600) with accelerating voltages of 20 kV (see, for example, FIGS. 26-32).

[0090] In an example embodiment, the acid leached ground mineral or ore is loaded onto a second non-corrosive tray 108. For example, a bed of approximately 2.0 g of acid leached ground rutile was loaded onto a second non-corrosive tray 108 (e.g., a stainless steel tray) which was suspended over a bed of approximately 5.0 g of Mg powder loaded on a first non-corrosive tray 108 (e.g., a stainless steel tray). In an example embodiment, the Mg powder is used in excess. The trays 108 of sodium titanate and Mg power are placed in a non-corrosive reaction chamber 112 that is then sealed with a lid 104. In an example embodiment, the rim of the sealed container 112 was covered by a ceramic paste 114 to further seal the chamber. The sealed reaction chamber 112 was placed in a furnace and the chamber was saturated and/or filled with inert gas (e.g., Argon gas) via the inert gas inlet 102. In an example embodiment, the sealed reaction chamber 112 is heated to approximately 950 C. within the furnace (at block 408). The reaction is continued for approximately 2 h in an example embodiment. After the reaction has been continued for approximately 2 h, the inert gas is removed from the sealed reaction chamber 112 via an inert gas outlet (not shown) and the reaction chamber 112 is actively and/or passively cooled to room temperature (e.g., approximately 18-30 C.). In an example embodiment, the resulting product was subjected to ultrasound assisted bath leaching (e.g., for 30 min with ultrasound at a frequency of 40 kHz) with dilute HCl (e.g., 1 M, 100 ml) one or more times (e.g., three times) to remove magnesium oxide. The product was rinsed with distilled water to remove the acid residues and was dried at approximately 60 C., for example. For example, the reduction process may be similar to that described above with respect to FIGS. 2 and 2A.

[0091] The phase and crystallinity of the samples were analyzed by Powder X-ray Diffractometer (Bruker D8 Focus) with Cu K (=0.154 nm) irradiation in the 20 range of 5-90 at a scanning rate of 0.020 sec.sup.1. The morphology and element content of the products were studied by Scanning Electron Microscopy (SEM, Hitachi SU 6000600), with accelerating voltages of 5-20 kV coupled with Energy Dispersive X-ray spectrometer (EDX). Transmission Electron Microscopic imaging (TEM, JEOL 2100, operating at 200 kV) were carried out for internal structure studies and the elemental compositions were studied at the nanoscale using Electron Energy Loss Spectroscopy (EELS) (Gatan 963 EELS spectrometer at 0.05 eV/channel dispersion). The sample was first dispersed in methanol using ultrasound sonication bath at room temperature for 30 min and a drop of the dispersion was dried on a carbon coated Cu grid prior to conduct TEM/EELS studies.

[0092] The PXRD patterns of synthetic rutile, natural rutile and wet ground rutile after acid leaching are shown in FIG. 26. As shown by a comparison of FIG. 26(a) and FIG. 26(b), the natural rutile does not show all the characteristic peaks related to synthetic rutile. However, it was observed that there is a tendency of those peaks to be appeared with the treatments, suggesting that the structural changes of natural rutile to synthetic rutile occurs with the removal of iron impurities during the grinding and acid treatment (FIG. 26(c)).

[0093] The PXRD patterns of the products obtained after the reaction with Mg vapor at 950 C. for 2 h are shown in FIG. 27. The crystalline phases of both Ti and MgO were identified in the sample prior to leaching with acid (ICDD PDF number for Ti metal-44-1294 and MgO-4-829) as shown in FIG. 27(a), indicating that the rutile has been subjected to complete reduction by Mg vapor.

Rutile(s)+Mg(g).fwdarw.Ti(s)+MgO(s)

[0094] There is no evidence of formation of any mixed metal oxides, sub-oxides or alloys of Ti. FIG. 27(b) shows the product after leaching with acid followed by washing with distilled water. The presence of peaks corresponded only for pure Ti indicates that the MgO has been removed as MgCl.sub.2 during the acid leaching and washing process.

MgO(s)+Ti(s)+2HCl(aq).fwdarw.Ti(s)+MgCl.sub.2(aq)+H.sub.2O(l)

[0095] The SEM images of (a) natural rutile (b) synthetic rutile and (c) ground and acid leached natural rutile is shown in FIG. 28. As shown in FIG. 28, natural rutile shows granular morphology with the particle size less than 500 m. However, the particle size and the morphology of natural rutile became similar to that of synthetic rutile during the grinding followed by the acid leaching.

[0096] SEM image of the product obtained after the reduction with Mg vapor shown in FIG. 29. The Ti sponge before acid leaching shows a plate-like morphology as shown in FIG. 29(a), indicating the presence of MgO crystals over the Ti particles. When MgO has been leached out by the diluted HCl acid leaching process, the morphology has changed rapidly. As shown in FIG. 29(b), the particles comprise an irregular shaped morphology and specially a porous structure with the particle size ranging from 100-400 nm. The porous morphology of the particle surface might be due to the removal of surface bound MgO layer during the acid leaching and washing process.

[0097] Energy Dispersive X-Ray Diffraction results of the resulted Ti sponge before and after leaching with HCl acid also provide enough evidence to prove the removal of MgO impurities from the Ti sponge during the leaching process, as the EDX mapping of Ti sponge before acid leaching contains Ti, Mg and O (see FIG. 30). Further, according to the EDX results shown in FIG. 30(a), the Ti oxides in rutile reacted with Mg vapor before leaching with dilute HCl acid indicating the presence of Ti in the core of the particle and Mg and O as a coating around the Ti core. It suggests that the Ti sponge obtained after reducing rutile with Mg vapor results in a coreshell product in which the Ti particles are covered with an MgO layer.

[0098] Nevertheless, the absence of any other elements but the Ti in the EDX mapping of Ti sponge after leaching with HCl acid (see FIG. 31) is in agreement with the total removal of MgO impurities during the final dilute HCl acid treatment followed by the washing.

[0099] FIG. 32 shows the EELS results of Ti sponge before and after leaching with dilute HCl acid. According to the EELS results, the characteristic edges for Ti, O and Mg were appeared at K-edge values at 455 eV, 532 eV and 1305 eV respectively, which confirms that the only elements present in the Ti sponge prior to acid leaching is Ti, Mg and O (see FIG. 7(a)). Thus, the EELS results provide further evidence to prove that the Mg vapor results in a coreshell product where the Ti particles are covered with MgO layer, which is elucidated in FIG. 6. Interestingly in FIG. 7(b), the Mg edge at 1305 eV is totally disappears while remaining the Ti edge unchanged, which is again indicating the removal of MgO during the acid leaching and washing process as described previously under the FIG. 31.

[0100] Finally, by considering all the observations and analysis data, it can be concluded that the synthesis of pure Ti sponge by simple reduction process with Mg vapor has been successfully achieved from natural rutile sand.

[0101] 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.