METHOD FOR PRODUCTION OF A COMPOSITE MATERIAL USING EXCESS OXIDANT

Abstract

A method of producing a composite material comprising: supplying a metal compound (M.sub.PC) of a product metal (M.sub.P) and a reductant (R) capable of reducing the metal compound (M.sub.PC) of the product metal (MP) to a reactor; forming a composite material comprising a matrix of oxidised reductant (R.sub.0) of the reductant (R), the product metal (M.sub.P) dispersed in the matrix of oxidised reductant (R.sub.0), and at least one of (i) one or more metal compounds (M.sub.PC.sub.R) of the metal compound (M.sub.PC) in one or more oxidation states and (ii) the reductant (R); and recovering the composite material from the reactor, wherein the metal compound (M.sub.PC) of the product metal (M.sub.P) is fed to the reactor such that it is in excess relative to the reductant (R).

Claims

1. A composite material comprising: a matrix of oxidised reductant (R.sub.0); a product metal (M.sub.P) dispersed in said matrix of oxidised reductant (R.sub.0); and at least one of (i) one or more metal compounds (M.sub.PC.sub.R) of said product metal (M.sub.P) in one or more oxidation states, and (ii) a reductant (R).

2. A composite material according to claim 1, wherein said composite material comprises up to 20 wt % of said reductant (R).

3. A composite material according to claim 1, wherein said product metal (M.sub.P) is selected from the group consisting of titanium, aluminium, vanadium, chromium, niobium, molybdenum, zirconium, silicon, boron, tin, hafnium, yttrium, iron, copper, nickel, bismuth, manganese, palladium, tungsten, cadmium, zinc, silver, cobalt, tantalum, scandium, ruthenium and the rare earths or a combination of any two or more thereof.

4. A composite material according to claim 3, wherein said product metal (M.sub.P) comprises at least two of titanium, aluminium and vanadium.

5. A composite material according to claim 1, wherein said oxidised reductant (R.sub.0) comprises a metal halide (M.sub.RX) selected from the group consisting of MgCl.sub.2, NaCl, KCl, LiCl, BaCl.sub.2, CaCl.sub.2, BeCl.sub.2, AlCl.sub.3 and any combination thereof.

6. A composite material according to claim 1, wherein said reductant (R) is selected from the group consisting of Mg, Na, K, Li, Ba, Ca, Be, Al and any combination thereof, and any one or more thereof with another reductant (R′).

7. A composite material according to claim 1, wherein said one or more metal compounds (M.sub.PC.sub.R) of said product metal (M.sub.P) in one or more oxidation states comprise one or more metal halides (M.sub.PX) of said metal component (M.sub.P).

8. A composite material according to claim 1, wherein said composite material is in the form of particles having an average particle size of up to 500 μm, preferably from 20-300 μm.

Description

BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS

[0066] To further clarify various aspects of some embodiments of the present invention, a more particular description of the invention will be rendered by references to specific embodiments thereof, which are illustrated in the appended drawings. It should be appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting on its scope. The invention will be described and explained with additional specificity and detail through the accompanying drawings in which:

[0067] FIG. 1 illustrates a flow chart of a method for the production of composite material, including additional illustration of options for the treatment of the recovered composite material.

[0068] FIG. 2 shows a thermogram of the sample of Example 1 over the relevant temperature range for the solid to liquid transition of magnesium.

[0069] FIG. 3 shows a thermogram of the sample of Example 2 over the relevant temperature range for the solid to liquid transition of magnesium.

[0070] FIG. 4 shows a cross section of the metal particles following removal of volatile halides according to Example 8.

[0071] FIG. 5 shows the DTA thermogram of the composite particle of Example 9 around the temperature of 650° C. exhibiting no endotherm to indicate the presence of metallic magnesium.

[0072] FIG. 6 shows a thermogram of the composite product of Example 10 surrounding the temperature of the melting point of aluminium of 660° C.

[0073] FIG. 7 shows a cross section of the metal particles of Example 10 following removal of volatile halides.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] Hereinafter, this specification will describe the present invention according to the preferred embodiments. It is to be understood that limiting the description to the preferred embodiments of the invention is merely to facilitate discussion of the present invention and it is envisioned without departing from the scope of the appended claims.

[0075] Referring to FIG. 1, a flow chart of a method 100 for the recovery of a composite material is illustrated. The flow chart also includes processing options 200 for the recovered composite material.

[0076] According to the method 100 for the recovery of a composite material, metal compound (M.sub.PC) 110 of a product metal (M.sub.P) and a reductant (R) 120 capable of reducing the metal compound (M.sub.PC) 110 of the product metal (M.sub.P) are supplied to a reactor 130. The amount of metal compound (M.sub.PC) 110 supplied to the reactor 130, including any recycled metal compound (M.sub.PC) 140, is in excess relative to the amount of reductant 120 available for reaction in the reactor 130. Composite material 150 is recovered from the reactor 130. The composite material comprises a matrix of an oxidised reductant (R.sub.0) of the reductant (R), the product metal (M.sub.P) dispersed in the matrix, and at least one of (i) a reduced metal compound (M.sub.PC.sub.R) of the metal compound (M.sub.PC) and (ii) the reductant (R).

[0077] The reactor 130, which will be discussed in terms of a fluidised bed reactor with reference to FIG. 1, is run at a temperature that maintains the finely divided form of the composite material. The temperature is below the melting point of the oxidised reductant (R.sub.0) of the reductant (R) 120, which forms part of the composite material 150. Generally, the temperature may also be close to or above the melting point of the reductant (R) 120. Where the temperature in the reactor 130 is between the melting point of the reductant (R) 120 and the melting point of the oxidised reductant (R.sub.0), for example its oxidised salt, the reaction of the reductant (R) 120 with oxidant results in the formation of a composite material 150 comprised of largely or entirely solid character. This ‘freezing’ reaction advantageously has the impact of creating finely divided and highly pure reaction products. Without seeking to be bound by theory, it is thought that the particle size of the composite material 150 is such that the finely divided elements comprised within are sufficiently small that they interact differently with visible light than their bulk counterparts. For example, they may appear black or dark in colour. The finely divided structure of the composite material 150 product has advantages compared to composites of analogous nominal compositions that do not have the same finely divided structure. These advantages will be elucidated in more detail below.

[0078] Where the reductant (R) 120 is fed into the reactor 130 as a solid or solid particulate, the prevailing conditions in the reactor 130 ensure, with sufficient time, the melting of the reductant 120. The time required for melting of solid reductant 120 depends upon numerous factors, including the feed mechanism, whether the reductant 120 is fed with other materials, the temperature of the reactor 130, the reaction intensity of the reactor 130 per unit volume, the particulate density of the reductant 120 feed at any single location and, if other reductant or reagent or inert streams are in or are entering into the reactor, the proximity to these components and their respective temperatures when impinging on particles of the reductant 120.

[0079] The interaction of the reductant (R) 120 upon contacting other surfaces in the reactor 130 will depend on its phase at that time. If the reductant 120 particle is solid, it is possible the reductant 120 particle will collide and rebound. It will then continue to interact with other surfaces and environments in the reactor 130.

[0080] If the reductant 120 particle has a molten external surface and solid inner surface, it is possible the particle will adhere to any surface it impacts, creating a composite of the two objects. The particle will then continue to interact with other surfaces and environments in the reactor 130.

[0081] If the reductant 120 particle is molten when it interacts with other surfaces, it may wet the surface. Depending upon the nature of the solid-liquid interaction the thickness of the layer formed will vary. It is considered that this may be manipulated through varying intensity of interactions, density of reductant 120 feed, temperature and time, etc.

[0082] Whether the end location of molten reductant in the reactor 130 is as a stand-alone mass, wetted on a surface or combined with other surfaces, at some point it will generally interact with oxidant and react. At this point the thickness or the wetted layer or size of the molten mass or particle is considered of some importance in determining the extent of reaction of the reductant (R) 120 and the morphology of the final composite material 150.

[0083] If the particle or wetted layer is sufficiently large or not completely molten at this time, the freezing nature of the reaction as described previously can result in a proportion of the reductant (R) becoming encapsulated by the composite material 150. Where the surface exposed to oxidant reacts to form a solid it may form a barrier (i.e. shell) that may restrict or eliminate the participation of the remaining reductant in further reduction. If the particle is sufficiently small or the wetted layer sufficiently thin, for example if the thickness of the reaction layer is equivalent to the radius of the particle or the thickness of the wetted layer, the process can consume the majority if not all of the reductant (R).

[0084] The amount of oxidant in the reactor relative to reductant (R) will be an important factor in determining the probability of the above mentioned interactions. Weighting of one form of interaction over others can be manipulated by changing operating conditions, feed forms, etc. The nature of surfaces in the reactor available for interaction, potential for sequential ordering and forms in which the reductant and oxidant are brought into contact can result in composites being formed which have diverse characteristics. These may include, without limitation, excess or fully consumed reductant, layers of composite, layers of composite with magnesium interstitial layers. It is thought that novel structured materials may be formed by sequential layering of dissimilar layers of prescribed composition.

[0085] Once the composite material is recovered 150, it may be stored under suitable conditions for later use, or may be processed 200 in various ways. The processing may include, without limitation, recovery of the product metal (M.sub.P) 210, combining the composite material with composite material of other product metal (M.sub.P) 220, and/or other compounding material (C.sub.M) 230. As such, it is envisaged that various products may be recovered, including without limitation product metal (M.sub.P), an alloy or mixture of product metals (M.sub.P/M.sub.P′) 240, and a mixture or composite product (M.sub.P/C.sub.M) 250. In any of these recovery processes, it may also be desirable to recover reductant (R) and optionally return this to the reductant feed 120.

[0086] The recovery of product from the composite materials of the present invention is described in detail in a co-pending International patent application with the title “METHOD FOR RECOVERY OF METAL-CONTAINING MATERIAL FROM A COMPOSITE MATERIAL”, filed on the same date as the present application. The content of the co-pending application is incorporated herein in their entirety.

EXAMPLES

[0087] The following examples are provided for exemplification only and should not be construed as limiting on the invention in any way.

Example 1

Production of Titanium Metal Composite in the Presence of Excess Oxidant with Unreacted Reductant Present in the Composite

[0088] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 20 kilograms of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were introduced.

[0089] Titanium tetrachloride was supplied at a rate of 8 kilograms per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 2 kilograms per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions titanium tetrachloride is in excess by approximately 2.5 wt % relative to magnesium as the most electrochemically positive component that could be oxidised in the reactor.

[0090] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0091] The product stream from the reactor included free flowing black spheres (<3 mm diameter). Titanium tetrachloride was observed in the exhaust gas stream of the reactor.

[0092] The initial chemical composition of the bed is shown in the first line Table 1 below. Samples from the product stream were taken hourly with compositions of these shown in subsequent lines of Table 1.

[0093] The composition of the product is shown to be consistent and to contain a relatively constant composition of titanium and magnesium as determined by XRF over a period of time. The composition of these particles indicates that they contain additional magnesium and less titanium than would be expected for stoichiometric reaction of titanium tetrachloride and magnesium (20.4% Mg and 20.1% Ti) despite the presence of excess oxidant. This indicates that the composite particles contain at least some magnesium metal that was not oxidised.

[0094] FIG. 2 shows a thermogram of the sample over the relevant temperature range for the solid to liquid transition of magnesium. The endotherm centred at 650° C. confirms the presence of a quantity of unreacted magnesium metal.

[0095] Heating of the composite particles from this run under prevailing conditions to remove the excess magnesium and magnesium chloride salt left titanium metal particles.

TABLE-US-00001 TABLE 1 Titanium with constant excess Mg in composite Ti (total) Mg Mg in excess (wt %) (wt %) (%) 19.44 20.7 4.9 19.52 20.8 4.9 19.6 21.1 6.0 19.59 21.3 7.1 19.51 21.1 6.5 19.58 21 5.6 19.46 20.8 5.3 19.76 21 4.7 19.55 21 5.8 19.49 20.8 5.1 19.56 20.8 4.7 19.55 20.6 3.8 19.62 20.8 4.4 19.58 21.1 6.1 19.57 21.3 7.2 19.6 21.4 7.5 19.36 20.9 6.3 19.55 20.8 4.8 NOTE: Mg in excess = (wt % Mg/wt % Ti)/(2 * MW(Mg)/MW(Ti)) * 100 − 100 where the wt % of Ti and Mg is in all forms, metallic or oxidised as measured using a technique such as XRF.

Example 2

Production of Titanium Composite in the Presence of Excess Oxidant Demonstrating the Minimisation of Unreacted Reductant Present in the Composite

[0096] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 20 kilograms of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were introduced.

[0097] Titanium tetrachloride was supplied at a rate of 6.3 kilograms per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 1.5 kilograms per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions titanium tetrachloride is in excess by 7.5 wt % relative to magnesium that could be oxidised in the reactor.

[0098] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0099] The product stream from the reactor included free flowing black spheres (<3 mm diameter). Titanium tetrachloride was observed in the exhaust gas stream of the reactor.

[0100] The initial chemical composition of the bed is shown in the first line of Table 2. Samples from the product stream were taken hourly with compositions of these shown in subsequent lines of Table 2.

[0101] The impact of a more significant excess of titanium tetrachloride fed into the reactor than in example 1 is observed in the reduction of unreacted magnesium being present in the composite particle samples over time. The final composition of these particles indicates that they contain very little to no additional magnesium than would be expected for stoichiometric reaction of titanium tetrachloride and magnesium despite the presence of excess oxidant.

[0102] FIG. 3 shows a thermogram of the sample over the relevant temperature range for the solid to liquid transition of magnesium. The absence of an endotherm centred around 650° C. confirms that no substantive unreacted magnesium metal is present in the sample.

[0103] Heating of the composite particles from this run under prevailing conditions to remove the magnesium chloride and the little, if any, excess magnesium left titanium metal particles.

TABLE-US-00002 TABLE 2 Titanium with reducing excess Mg in composite to low level Ti (total) Mg Mg in excess (wt %) (wt %) (wt %) 19.80 20.63 2.6 19.75 20.57 2.6 19.73 20.42 2.0 19.72 20.29 1.3 19.86 20.26 0.4 19.92 20.31 0.4 19.86 20.27 0.5 19.71 20.19 0.9 19.84 20.24 0.4

Example 3

Production of Titanium Composite in the Presence of Excess Oxidant Demonstrating the Formation of Larger Amounts of Sub-halides

[0104] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 20 kilograms of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were introduced.

[0105] Titanium tetrachloride was supplied at a rate of 7.3 kilograms per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 1.5 kilograms per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions titanium tetrachloride is in excess by approximately 25 wt % relative to magnesium fed into the reactor.

[0106] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0107] The product stream from the reactor included free flowing black spheres (<3 mm diameter). Titanium tetrachloride was observed in the exhaust gas stream of the reactor.

[0108] The initial chemical composition of the bed is shown in the first line of Table 3. Samples from the product stream were taken hourly with compositions of these shown in subsequent lines of Table 3.

[0109] The impact of a more significant excess of titanium tetrachloride fed into the reactor than in example 2 is observed in the reduction of magnesium being present in the composite particle samples over time. The final composition of these particles indicates that they contain less magnesium and more titanium than would be expected for the stoichiometric reaction of titanium tetrachloride and magnesium. The total quantity of magnesium and titanium is also greater than would be expected for the stoichiometric reaction of titanium tetrachloride and magnesium, implying a reduction in total chlorine content of the composite. These factors all point to the composite containing increased levels of partially reduced titanium chlorides with little to no metallic magnesium.

[0110] Heating of the composite particles from this run under prevailing conditions to remove the excess magnesium chloride and partially reduced titanium chlorides leaves behind titanium metal particles.

TABLE-US-00003 TABLE 3 Titanium with reducing excess Mg in composite until formation of sub- halides Ti (total) Mg Mg in excess (wt %) (wt %) (wt %) 20.21 21.0015 2.3 20.04 22.159 8.9 20.2 21.2115 3.4 20.455 21.0395 1.3 20.375 20.6395 −0.3 20.425 20.479 −1.3 20.41 20.341 −1.9 21.335 21.066 −2.8 20.695 20.367 −3.1 20.24 20.1885 −1.8 20.615 20.258 −3.2 20.46 20.1065 −3.2 20.605 20.058 −4.1

Example 4

Titanium-Aluminium-Vanadium Composite

[0111] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 200 grams of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were introduced.

[0112] Titanium tetrachloride was supplied at a rate of 424 grams per hour, vanadium tetrachloride was supplied at a rate of 18 grams per hour and aluminium chloride was supplied at a rate of 36 grams per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 113 grams per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions TiCl.sub.4, VCl.sub.4 and AlCl.sub.3 are in excess by a total of 47% relative to the amount of magnesium that could be oxidised in the reactor.

[0113] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0114] The product stream, from the reactor included free flowing black spheres (<3 mm diameter). Metal halides were observed in the exhaust gas stream of the reactor.

[0115] A sample from the product stream was taken and subjected to heating under prevailing conditions to remove metal halides and any excess magnesium leaving behind titanium-aluminium-vanadium containing particles. This is shown in Table 4.

TABLE-US-00004 TABLE 4 Composition of metal component retained after removal of volatiles from Titanium - Aluminium - Vanadium composite. Sum Ti Mg Al V As Bi Co Cr Fe Mn (%) % % % % Ppm ppm ppm ppm ppm ppm <0.002 <0.002 <0.002 <20 <20 <20 <20 <20 <20 99.0 91.1 0.11 2.24 4.93 <20 <20 55 790 3826 368 99.0 91.2 0.10 2.22 4.87 <20 <20 28 759 3744 376 Mo Na Nb Ni Pb Si Y Zr W Sn Ppm ppm ppm ppm Ppm ppm ppm ppm Ppm Ppm <20 <20 <20 <20 <20 <20 <20 <20 <50 <20 119 113 <20 779 <20 <20 <20 31 <20 n/a 117 81 <20 738 <20 54 <20 23 <20 n/a

[0116] The ratios of metal compounds fed into the reactor were approximately 90% Ti, 6% Al and 4% V on a metal mass basis. Despite this, the final metal composition of Ti 91%, Al 2.24% and V 4.93% indicates that each different halide has a differing conversion in the reactor. As such, to be able to achieve a specific desired composition it is essential to feed at least one oxidant in excess to drive the reduction-oxidation reactions to the desired degrees.

Example 5

Production of Vanadium Composite

[0117] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 200 grams of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were introduced.

[0118] Vanadium tetrachloride was supplied at a rate of 454 grams per. In this example the reductant phase was magnesium metal, supplied at a rate of 95 grams per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions vanadium tetrachloride is in excess relative to magnesium reductant that could be oxidised in the reactor.

[0119] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0120] The product stream from the reactor included free flowing black spheres (<3 mm diameter).

[0121] A sample from the product stream was taken and subjected to heating under prevailing conditions to remove metal halides and any excess magnesium left predominantly vanadium containing particles. Those skilled in the art would appreciate that with more extended operation that the titanium content of the composite particle and separated metal particle reduces to below detection levels.

Example 6

Zirconium

[0122] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 200 grams of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were applied.

[0123] Zirconium tetrachloride was supplied at a rate of 211 grams per. In this example the reductant phase was magnesium metal, supplied at a rate of 40 grams per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions zirconium tetrachloride is in excess relative to magnesium reductant fed into the reactor.

[0124] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0125] The product stream from the reactor included free flowing black spheres (<3 mm diameter). Zirconium tetrachloride was observed in the exhaust gas stream of the reactor.

[0126] A sample from the product stream was taken and subjected to heating under prevailing conditions to remove metal halides and any excess magnesium left predominantly zirconium containing particles. Those skilled in the art would appreciate that with more extended operation that the titanium content of the composite particle and separated metal particle reduces to below detection levels.

Example 7

Ti-Al Composite with Mg as Reductant.

[0127] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 680° C. The system was charged with 200 grams of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 655° C. At this point reactant feeds were applied.

[0128] Titanium tetrachloride was supplied at a rate of 424 grams per and aluminium chloride was supplied at a rate of 148 grams per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 102 grams per hour as a finely divided powder conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions oxidant halides are in excess relative to magnesium reductant fed into the reactor.

[0129] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 680° C. for an extended period.

[0130] The product stream from the reactor included free flowing black spheres (<3 mm diameter). Oxidant halides were observed in the exhaust gas stream of the reactor.

[0131] A sample from the product stream was taken and subjected to heating under prevailing conditions to remove metal halides and any excess magnesium leaving behind titanium-aluminium containing particles. The composition of the sample is shown in Table 5.

TABLE-US-00005 TABLE 5 Titanium-Aluminide Sum Ti Mg Al V As Bi Co Cr Fe Mn (%) % % % % ppm ppm ppm ppm ppm ppm <0.002 <0.002 <0.002 <20 <20 <20 <20 <20 <20 95.4 82.4 0.17 12.6 0.01 58 <20 122 192 1578 629 Mo Na Nb Ni Pb Si Y Zr W Sn ppm Ppm ppm ppm ppm ppm ppm ppm ppm Ppm <20 <20 <20 <20 <20 <20 <20 <20 <50 <20 <20 <20 <20 87 <20 215 <20 53 <20 n/a

Example 8

Production of Titanium Metal Composite in the Presence of Excess Oxidant with Unreacted Reductant Present in the Composite Below the Melting Point of the Reductant.

[0132] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 525° C. The system was charged with 2 kilograms of titanium composite particles as a seed material. The system was allowed to reach an internal temperature of 520° C. At this point reactant feeds were introduced.

[0133] Titanium tetrachloride was supplied at a rate of 1.2 kilograms per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 300 grams per hour as a finely divided powder with a particle size between 50-63 μm and was conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions titanium tetrachloride is in excess by approximately 3.5 wt % relative to magnesium as the most electrochemically positive component that could be oxidised in the reactor.

[0134] The addition of the reactants to the reactor increased the temperature in the reactor consistent with the exothermic nature of the reactions, reaching a steady bed temperature of 550° C. for an extended period.

[0135] The product stream from the reactor included free flowing black spheres (<3 mm diameter). Titanium tetrachloride was observed in the exhaust gas stream of the reactor.

[0136] Under these conditions the reductant is solid and the oxidant is a vapour. This limits the reactivity of the reductant where the exterior shell of reductant particles reacts (˜10-20 μm) based on each particles residence time in the reactor. As such, the core of reductant particles greater than the reaction shell remains in metallic form.

[0137] Heating of the composite particles from this run under prevailing conditions to remove the excess magnesium and magnesium chloride salt left titanium metal particles. The mass fraction of metal product to composite during this process is 16%.

[0138] FIG. 4 shows a cross section of the metal particles following removal of volatile halides. It can be seen that the particles have a wall thickness of 10-20 μm and a hollow core of 20-40 μm. It is considered that the hollow core would have contained metallic magnesium prior to removal of volatiles. The composition of the bright phase is essentially 100% titanium.

[0139] This example shows that only a limited shell thickness of magnesium has been reacted and exemplifies the definition of the reductant to only include the material which is capable of being reduced in the prevailing conditions.

Example 9

Very High Excess of TiCl.SUB.4

[0140] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 525° C. The system was charged with 2 kilograms of titanium composite particles as a seed material as derived from the conditions prevailing from Example 8. The system was allowed to reach an internal temperature of 520° C. At this point reactant feeds were introduced.

[0141] Titanium tetrachloride was supplied at a rate of 1.2 kilograms per hour. In this example the reductant phase was magnesium metal, supplied at a rate of 10 grams per hour as a finely divided powder with a particle size between 50-63 μm and conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions titanium tetrachloride is in excess by approximately 3000 wt % relative to magnesium as the most electrochemically positive component that could be oxidised in the reactor.

[0142] The addition of the reactants to the reactor increased the temperature in the reactor consistent with a mild exothermic reaction, reaching a steady bed temperature of 530° C. Over a period of time the bed temperature reduced towards the starting temperature prior to feeds being introduced.

[0143] The product stream from the reactor included free flowing black/green spheres (<3mm diameter). A significant quantity of titanium tetrachloride was observed in the exhaust gas stream of the reactor. The mass of material discharged from the reactor to maintain a constant reactor mass was greater than that would be expected for the conversion of the magnesium fed into the reactor if converted into composite material. This implies that titanium tetrachloride was being incorporated into the composite particles by reacting with compounds other than the fed magnesium.

[0144] Under these conditions the reductant is solid and the oxidant is a vapour. The feed rate of reductant into the reactor relative to the bed size increases the residence time significantly, providing a greater time for reactions to occur and the extent of reaction to increase, including for magnesium in the seed bed to be converted.

[0145] FIG. 5 shows the DTA thermogram of the composite particle around the temperature of 650° C. exhibiting no endotherm to indicate the presence of metallic magnesium.

[0146] Heating of the composite particles from this run under prevailing conditions to remove the excess magnesium and magnesium chloride salt left titanium metal particles. The mass fraction of metal product to composite during this process is 12%.

[0147] The combination of no metallic magnesium in the composite and reduced metallic mass retained after removal of volatiles indicates an enhanced level of reaction of solid phase magnesium beyond the surface 10-20 μm with longer residence time in conditions of significant excess of oxidant. Also the formation of a significant portion of sub-halides present in the composite particle can be similarly confirmed.

Example 10

Aluminium as a Reductant

[0148] A reaction vessel made from stainless steel was purged with high purity argon and heated externally to 200° C. The system was charged with 2 kilograms of titanium composite particles formed under similar conditions previously as a seed material. The system was allowed to reach an internal temperature of 190° C. At this point reactant feeds were introduced.

[0149] Titanium tetrachloride was supplied at a rate of 1.2 kilograms per hour. In this example the reductant phase was aluminium metal, supplied at a rate of 150 grams per hour as a finely divided powder with a d.sub.50 particle size of around 25 μm and was conveyed in a low volume of argon gas carrier stream entering the reactor. In these proportions titanium tetrachloride is in excess by approximately 50wt % relative to aluminium as the most electrochemically positive component that could be oxidised in the reactor.

[0150] The addition of the reactants to the reactor increased the temperature in the reactor consistent with a minor exothermic nature of the reactions, reaching a steady bed temperature of 215° C. for an extended period.

[0151] The product stream from the reactor included fine black/grey particles (<1 mm diameter). Titanium tetrachloride was observed in the exhaust gas stream of the reactor.

[0152] Under these conditions the reductant is solid and the oxidant is a vapour. Also, the oxidised reductant (AlCl.sub.3) is notionally a vapour at this temperature also and not available to form a part of the protective matrix for the reduced metal. In this example the titanium subhalides form part of the composite particle protective matrix.

[0153] FIG. 6 shows a thermogram of the composite product surrounding the temperature of the melting point of aluminium of 660° C. A clear endotherm is observed indicating the presence of metallic aluminium consistent with analogous result in example 9. Exotherms are observed above and below the melting point of aluminium which are consistent with the formation of titanium aluminides.

[0154] FIG. 7 shows a cross section of the metal particles following removal of volatile halides. The composition of the bright phase is 63% Aluminium and 27% Titanium, consistent with TiAl.sub.3.

[0155] While the above examples primarily employ magnesium metal as the reductant, those in the art will appreciate that other metals, including but not limited to sodium, potassium, lithium and barium, would be expected to achieve similar results given their similar properties.

[0156] Unless the context requires otherwise or specifically stated to the contrary, integers, steps or elements of the invention recited herein as singular integers, steps or elements clearly encompass both singular and plural forms of the recited integers, steps or elements.

[0157] It will be appreciated that the foregoing description has been given by way of illustrative example of the invention and that all such modifications and variations thereto as would be apparent to persons of skill in the art are deemed to fall within the broad scope and ambit of the invention as herein set forth.