PYROPHORIC METALS AND METAL ALLOYS

Abstract

A process for producing a Ti or Ti alloy product includes exposing particles of pyrophoric Ti metal and Ti alloys to a liquor, gas or vapour that includes a passivation component that forms a passivated protective layer with Ti on surfaces of the particles.

Claims

1. A process for producing a Ti or Ti alloy product including exposing particles of pyrophoric Ti metal and Ti alloys to a liquor, gas or vapour that includes a passivation component that forms a passivated protective layer with Ti on surfaces of the particles of pyrophoric Ti metal and Ti alloys.

2. The process defined in claim 1 wherein the passivation component is one or more than one of oxygen, nitrogen and a hydrocarbon.

3. (canceled)

4. The process defined in claim 1 including controlling the exposure step so that the oxygen concentration of particles of pyrophoric Ti metal and Ti alloys that are non-spherical particles of up to 250 m have an increased concentration of oxygen of at least 100 ppm over the oxygen concentration of non-spherical particles of pyrophoric Ti metal and Ti alloys that do not have the passivation layer.

5. The process defined in claim 1 including controlling the exposure step so that the oxygen concentration of particles of pyrophoric Ti metal and Ti alloys that are of spherical particles of up to 250 m that have the passivation layer have an increased concentration of oxygen of at least 100 ppm over the oxygen concentration of spherical particles of pyrophoric Ti metal and Ti alloys that do not have the passivation layer.

6. The process defined claim 1 including controlling the exposure step so that the oxygen concentration of particles that have the passivation layer is less than 4000 ppm.

7. The process defined in claim 1 wherein the passivation layer is a separate layer on an existing surface of the particles of pyrophoric Ti metal and Ti alloys.

8. The process defined in claim 1 wherein the passivation layer is a result of reactions between the passivation component and the pyrophoric Ti metal and Ti alloys.

9. (canceled)

10. The process defined in claim 1 wherein the passivation layer includes an oxide.

11. The process defined claim 1 wherein the exposure step includes removing at least a part of a contaminant from the particles of pyrophoric Ti metal and Ti alloys so that the metal product is a purer metal product, wherein the contaminant includes a metal halide including any one or more of MgCl.sub.2, NaCl, KCl, LiCl, BaCl.sub.2, CaCl.sub.2, AlCl.sub.3, TiCl.sub.2, TiCl.sub.3, and BeCl.sub.2.

12-14. (canceled)

15. The process defined in claim 1 wherein the liquor is selected from any one or more than one of: water, alcohols, such as ethanol or methanol, ethers, ketones, aliphatic hydrocarbons, nitriles, furans, and esters.

16. The process defined in claim 1 includes exposing particles of pyrophoric Ti metal and Ti alloys to the liquor in an agitated vessel.

17. The process defined in claim 1 includes rinsing the particles to remove contaminants after the exposure step.

18. The process defined in claim 17 includes multiple exposure and rinse steps.

19. A process for producing a Ti metal or a Ti alloy product comprising the following steps: (a) reducing TiCl.sub.4 in a fluidised bed reactor (FBR) with a Mg reductant and producing Ti metal particles dispersed in a protective MgCl.sub.2 matrix, (b) removing the protective matrix in a vacuum distillation unit and producing particles of Ti metal or a Ti alloy in situations where other metals such as Al and V are formed in the fluidised bed reactor; and (c) exposing the particles of the pyrophoric Ti metal or Ti alloys to a liquor, gas or vapour that contains a passivation component that forms a protective passivation layer with Ti on the surface of the particles.

20. The process defined in claim 19 wherein the exposure step reduces a chloride concentration in the particles of the pyrophoric Ti metal or Ti alloy.

21. The process defined in claim 19 wherein the exposure step reduces the chloride concentration in the particles of the pyrophoric Ti metal or Ti alloys by at least 20 ppm.

22. The process defined in claim 19 includes milling particles produced in the matrix removal step before carrying out the exposure step.

23. The process defined in claim 19 includes a rinse step after the exposure step.

24. (canceled)

25. An apparatus for producing a Ti metal and Ti alloy product that comprises a contact unit that is configured to bring into contact particles of pyrophoric Ti metal and Ti alloys and a liquor, gas or vapour that includes a passivation component that can form a protective passivation layer on surfaces of the particles of the pyrophoric Ti metal and Ti alloys.

26. The apparatus defined in claim 25 wherein the contact unit includes a vessel for the particles of pyrophoric Ti metal and Ti alloys and the liquor that contains the passivation component and an agitator for mixing the particles and the liquor.

27. (canceled)

Description

BRIEF DESCRIPTION OF THE DRAWING

[0167] The invention is described further hereinafter with reference to the following Figures, of which:

[0168] FIG. 1 is a flow chart of an embodiment of a process and an apparatus for producing Ti metal and Ti alloy products in accordance with the invention;

[0169] FIG. 2 is a graph of oxygen analysis of samples of pyrophoric Ti metal particles passivated with methanol and THF under different conditions in test work carried by the applicant;

[0170] FIGS. 3 and 4 are graphs of oxygen uplift and chloride concentrations, respectively, for samples of pyrophoric Ti metal particles passivated with ethanol under different conditions in test work carried by the applicant;

[0171] FIGS. 5 and 6 are graphs of oxygen uplift and chloride concentrations, respectively, for samples of pyrophoric Ti metal particles passivated with THF under different conditions in test work carried by the applicant;

[0172] FIGS. 7 and 8 are graphs of oxygen uplift and chloride concentrations, respectively, for samples of pyrophoric Ti metal particles passivated with methanol under different conditions in test work carried by the applicant;

[0173] FIGS. 9 and 10 are graphs of oxygen uplift and chloride concentrations, respectively, for samples of pyrophoric Ti metal particles passivated with water under different conditions in test work carried by the applicant;

[0174] FIGS. 11 and 12 are graphs of oxygen uplift and chloride concentrations, respectively, for samples of pyrophoric Ti metal particles passivated with dimethoxyethane (DME) under different conditions in test work carried by the applicant;

[0175] FIG. 13 is a graph of oxygen uplift for samples of pyrophoric Ti metal particles passivated with n-pentane under different conditions in test work carried by the applicant; and

[0176] FIG. 14 is a graph of oxygen uplift for samples of pyrophoric Ti metal particles passivated with acetonitrile under different conditions in test work carried by the applicant.

DESCRIPTION OF EMBODIMENTS

[0177] The embodiment of the invention shown in FIG. 1 produces an air stable Ti metal and Ti alloy products with low concentrations of contaminants from pyrophoric Ti metal and Ti alloys, with no major chemical changes to the Ti metal and Ti alloys.

[0178] As noted above, the invention is based on a realisation that the pyrophoricity of pyrophoric Ti metal and Ti alloy particles produced by the applicant's process described in WO 2017/027915, WO 2017/027915 and WO 2017/027914 and other patent families can be decreased and the purity of Ti metal and Ti metal alloy particles can be maintained or increased by a passivation step of contacting the particles with a suitable liquor, gas, or vapour that contains a passivation component.

[0179] In particular, the applicant has found that a liquor contact step or a gas contact step a vapour contact step can: [0180] (a) form a protective oxide layer on surfaces of pyrophoric Ti metal and Ti alloy particles; and/or [0181] (b) remove contaminants from these particles.

[0182] In one embodiment of the present invention shown in FIG. 1, the process includes contacting Mg with TiCl.sub.4, AlCl.sub.3 and VCl.sub.4 in a fluidised bed reactor (FBR) 3 and forming a composite material 7 containing TiAlV (Ti64) particles dispersed in a MgCl.sub.2 matrixalso known as poppy seed. Typically, the MgCl.sub.2 is at least 90% by volume of the poppy seed 7. The composite poppy seed 7 is discharged from the FBR 3. The poppy seed 7 is transferred to and treated in a continuous vacuum distillation unit (CVDU) 13 to remove MgCl.sub.2 by vacuum distillation. The vacuum distillation results in the poppy seed forming a coalesced mass of particles, metal product 15. The resultant metal product 15 containing Ti64 particles is discharged from the CVDU and is milled in a mill 17 to a desired particle size. The milled particles are mixed with a suitable liquor such as ethanol in a liquor exposure step in an agitated vessel 19. This liquor contact step forms a protective passivation layer on surfaces of the particles and at least substantially removes residual MgCl.sub.2 from the Ti64 particles. The resultant slurry produced in the liquor contact step is discharged from the agitated vessel, rinsed 21, and dried in a dryer 23 to form Ti64 particles.

[0183] The liquor contact step facilitates a passivation layer forming on the surfaces of the Ti64 particles which protects the Ti64 particles from oxidation. Specifically, ethanol passivates the surfaces of the Ti64 particles discharged from the CVDU.

[0184] The liquor contact step provides a higher level of purity of the Ti64 particles than the purity achieved with the CVDU on its own. Specifically, ethanol removes residual MgCl.sub.2 from the Ti64 particles discharged from the CVDU.

[0185] The above-described embodiment can be adapted to produce passivated particles of pyrophoric Ti metal and passivated particles of other pyrophoric Ti alloys.

[0186] For example, another embodiment of the invention that is substantially the same as that described in relation to FIG. 1 operates with Mg and TiCl.sub.4, in the FBR 3 and produces Ti metal particles.

[0187] One embodiment of a liquor contact step for passivating pyrophoric Ti metal particles includes a plurality, typically at least 2, more typically 2-6, successive liquor contact steps in a vessel, with ethanol (or other suitable liquor), and with the vessel having a ribbon blender (or other suitable agitator) for mixing 63 m particles of pyrophoric Ti metal.

[0188] The vessel may be any suitable construction and size.

[0189] The set-up for the embodiment includes: [0190] (a) Ethanol:Ti ratio in a range of 1 L:1 kg5 L:1 kg [0191] (b) Operating with a slight argon pressure in the vessel, and therefore keeping a bleed valve open.

[0192] The liquor contact step of the embodiment includes the following steps: [0193] 1. Fill vessel with pyrophoric Ti particles. [0194] 2. Supply ethanol under argon gas to the vessel. [0195] 3. Turn on ribbon blender in the vessel and mix the particles and ethanol for a selected period of time under argon. [0196] 4. Stop the blender and let the particles settle for before decanting ethanol down to the particle level in the vessel. [0197] 5. Repeat steps 1-4 for a selected number of times to complete passivation of the particles. [0198] 6. Leave the last wash inside the vessel for at least 8 hours. [0199] 7. After the last wash, transfer the slurry of passivated Ti metal particles and ethanol to a drying unit configured to allow ethanol to drain from the now-passivated particles and be removed from the unit before drying the particles in the unit. [0200] 8. Dry the passivated Ti metal particles under vacuum in the drying unit for a nominated time period.

Test Work

[0201] The applicant has carried out extensive test work with a number of different liquors, including liquors selected from water, alcohols (methanol and ethanol), ethers, ketones, furans, nitriles, aliphatic hydrocarbons, and esters.

[0202] The applicant has found in the extensive test work that is possible to produce Ti metal or Ti alloy products comprising Ti metal or Ti alloy particles that are passivated, i.e., non-pyrophoric, to the extent that the products comply with industry and customer standards for safe transportation and have concentrations of residual chloride that meet customer requirements for end-use applications.

[0203] A selection of the extensive test work is described below.

Water and Alcohol Passivation Test Work Development

[0204] The applicant conducted a series of successful phased passivation trials with Ti metal particles (which can be described as powders) in water and alcohol.

[0205] The phased trials found a dramatic reduction in reactivity ofTi.

[0206] Ti metal particles produced in accordance with the applicant's technology described in WO 2017/027915, WO 2017/027915, and WO 2017/027914 and in specifications in other patent families are pyrophoric, and as described above, there is a need to safely passivate while ensuring that the oxygen concentration in the powder to <3500 ppm, which ensures the product remains commercially relevant and within Ti industry product specifications.

[0207] Water, ethanol and methanol were selected as passivation liquors for the test work.

[0208] The applicant initially carried out the following phased trials on a laboratory scale. Ti metal particle samples were mixed with water, ethanol and methanol and the response of the samples to exposure to these liquors was assessed by measuring temperature rises in the passivation liquor. Temperature rises were taken as indications of reactions of Ti metal samples.

[0209] Table 1 provides a summary of the results of the phased trials.

TABLE-US-00001 TABLE 1 Description of phased trials - Ti particles passivation. Trial Justification Phase 1 Laboratory Literature precedents for Ti stability in water - see Corrosion Resistance of Ti, Ti Metals Corporation, 1997 Phase 2 Water - small scale Laboratory trials 10 L, 3 trials. Phase 3 Water - medium scale Evidence to move to phase 3 was minimal temperature 150 L, 1 trial. rise in water passivation experiments. Negligible reaction of Ti powder with water. Equipment design was determined satisfactory with 3 water-based trials. Phase 4 Ethanol - small scale 1. Transition to Phase 4 - water passivation was 15 L, 17 trials. scaled to 150 L safely, but the resultant passivated Ti was not a commercially relevant material (6000 ppm oxygen content). 2. Laboratory experiments in ethanol showed no temperature rise or visible reaction and resultant Ti powder exhibited oxygen that met industry specifications. Phase 5 Ethanol - medium scale Transition to Phase 5 - temperature rise <2 C. over 17 100 L in 200 L drum ethanol trials. Phase 6 Ethanol - medium scale, Transition to Phase 6 - similar scale, same solvent, vessel change, 150 L. vessel change to a ribbon blender. 6 trials. Phase 7 Methanol - medium Transition to Phase 7 - Laboratory trials were scale, same vessel as performed in methanol - no temperature rise. Phase 6, 150 L.

[0210] The phased trials 1-5 (Table 2) were carried out using the following equipment set-up: [0211] A stainless-steel bucket (20 L) was chosen as the vessel as it could contain the passivation liquor, argon flow in and out of the vessel was viable, and the vessel could facilitate Ti metal particles being fed in at a relatively small scale (2-5 kg). A stainless-steel lid was welded with the required fittings to allow for these engineering controls. [0212] A manifold was constructed to precisely control the argon flow and measure the oxygen content of the system. Oxygen levels were <7 ppm for all trials.

[0213] It was evident from the phased trials that there was effective passivation with methanol and ethanol.

Further Passivation Test Work (1)

[0214] Further test work was carried out by the applicant: [0215] (a) to understand the change in oxygen and chlorine levels of pyrophoric Ti metal particles (which can be described as being in a powder form) when subject to passivation with different liquids under ambient and pressure conditions; and [0216] (b) compared the performance (passivation and contaminant removal (chloride)) of ethanol and a cyclic-ether (THF).

[0217] Exposure of passivated pyrophoric Ti metal particles to air was also undertaken to measure oxygen uplift.

Experimental Steps

[0218] Argon-based Leco samples to determine oxygen and nitrogen concentrations of pyrophoric Ti metal particles (which can also be described as powders) were prepared. [0219] Leco analysis was performed on the samples. [0220] Air exposure of passivated Ti metal particles was conducted. [0221] Air-based Leco sample preparation and analysis was performed.

General Experimental Conditions

[0222] All tests were performed in an argon gas glovebox (GB) unless otherwise specified.

[0223] The pyrophoric Ti metal particles tested were produced in accordance with the applicant's technology described in WO 2017/027915, WO 2017/027915, and WO 2017/027914 and in specifications in other patent families.

[0224] Methanol was obtained from the applicant's production plant in Kwinana and used without further purification.

[0225] Tetrahydrofuran (THF) (Merck, anhydrous) was purchased from Rowe Scientific, was strictly stored in an argon glovebox, and was used without further purification.

[0226] The glovebox atmosphere was <10 ppm O.sub.2 during all experiments.

Passivation Experiments

[0227] Pyrophoric Ti metal particles (6.0 g) was placed into steel vials (50 mL). [0228] Liquid (10 mL) containing a passivation component was added to the vessel. [0229] The mixture was subjected to magnetic stirring for 10 minutes, followed by decanting of liquid. [0230] This was repeated 3 times (Table 1) for a total of 3 washes.

TABLE-US-00002 TABLE 3 Methanol and THF exposure conditions for a 1.sup.st wash, repeated 3 times MeOH THF Wash 1 Volume (mL) 10 10 Wash 1 temp ( C.) 36 36 Wash 1 time (mins) 10 10 Wash 1 agitation Mag. Stir Mag. Stir

[0231] After the third liquid wash and decanting, the slurry of particles and liquor was split into 2 parts, namely: [0232] A (atmosphere) samples. [0233] P (pressure) samples.

[0234] A Samples are samples that were not subjected to pressure. The samples were dried under vacuum overnight in the glovebox and stored under argon.

[0235] P Samples are samples that were subjected to 12 barg argon pressure.

[0236] More liquor (10 mL) was added to these slurry samples P. The mixture was placed in a 4-inch diameter ANSI tube with a graphite seal and sealed with a rattle gun to a maximum torque.

[0237] The following experiments were conducted in the ANSI tube: [0238] 3 methanol wash [0239] 3 THF wash

[0240] The ANSI tube was then pressurized with 10 barg argon pressure for 13 hours at room temperature (starting temperature of 36 C., finishing temperature of 24 C.).

[0241] After depressurizing the tube, the samples were removed.

[0242] All A and P samples were further split into 2 groups based on the gas that they were exposed to: [0243] Bexposure to argon gas only; and [0244] Airexposure to air for 24 hours.

[0245] In summary, the following samples were prepared and tested: [0246] 1. Liquor contact, no pressure, not air exposed. [0247] 2. Liquor contact, no pressure, air exposed. [0248] 3. Liquor contact, pressure, not air exposed. [0249] 4. Liquor contact, pressure, air exposed. [0250] 5. Baseno liquor, no pressure, air exposed

TABLE-US-00003 TABLE 4 Samples, codes and numbers created for the methanol and THF passivation test work Liquor Pressure Exposure Sample No. Analysis MeOH A1 B 689 3x LECO MeOH A2 B 690 3x LECO MeOH A3 B 691 3x LECO THF A1 B 692 3x LECO THF A2 B 693 3x LECO THF A3 B 694 3x LECO MeOH A1 Air 695 3x LECO MeOH A2 Air 696 3x LECO MeOH A3 Air 697 3x LECO THF A1 Air 698 3x LECO THF A2 Air 699 3x LECO THF A3 Air 700 3x LECO MeOH P1 B 701 3x LECO MeOH P2 B 702 3x LECO MeOH P3 B 703 3x LECO THF P1 B 704 3x LECO THF P2 B 705 3x LECO THF P3 B 706 3x LECO MeOH P1 Air 707 3x LECO MeOH P2 Air 708 3x LECO MeOH P3 Air 709 3x LECO THF P1 Air 710 3x LECO THF P2 Air 711 3x LECO THF P3 Air 712 3x LECO

[0251] B exposure samples in the above table were subjected to triplicate Leco preparation under argon gas.

[0252] As noted above, A exposure samples in the above table were exposed to air for 24 hours in a laboratory. After 24 hours they were transferred back into the glovebox for storage under argon and to maintain 24 hours air exposure. Upon Leco sample preparation, the air exposed samples were removed from the glovebox in small groups and Leco samples were prepared in the air.

[0253] Oxygen results of these samples are shown in FIG. 2.

[0254] FIG. 2 shows the oxygen concentrations for multiple samples for each category ((a) air exposed or argon gas exposed and (b) pressure or no pressure) for each liquor. Table 5 reports on the standard deviations for the samples.

TABLE-US-00004 TABLE 5 Oxygen average and standard deviation from FIG. 2 data Starting Starting MeOH THF MeOH no THF no MeOH THE MeOH THF Powder Powder ambient, ambient, pressure, pressure, pressure, pressure, pressure, pressure, #686 plus Air Ar Ar Air Air Ar Ar Air Air AVERAGE O2 2116 3838 2700 2530 3058 3191 3497 3270 3501 3253 Std Dev O2 91 67 12 157 112 187 271 203 134 122

[0255] Pyrophoric Ti metal particles were exposed to liquors at ambient conditions and maintained under argon, resulting in an oxygen concentration uplift, summarised below:

[0256] Liquor exposure at ambient/Ar, oxygen rise from pyrophoric Ti metal particles: [0257] Methanol600 ppm [0258] THF400 ppm

[0259] The ambient/Ar treated particles were subjected to the following conditions.

[0260] Exposed to air for 24 hours, oxygen rise from ambient/Ar: [0261] Methanol350 ppm [0262] THF 650 ppm

[0263] Exposed to pressure/liquor, no air, oxygen rise from ambient/Ar: [0264] Methanol800 ppm [0265] THF750 ppm

[0266] Exposed to pressure/liquor, plus air exposure, oxygen rise from ambient/Ar: [0267] Methanol800 ppm [0268] THF 750 ppm

[0269] The results show that oxygen uplift with liquor passivation is less than with air passivation.

[0270] In addition, there was less oxygen uplift with THF compared with methanol for ambient and pressure exposure of pyrophoric Ti metal particles.

Further Passivation Test Work (2)

[0271] Additional passivation test work was carried out by the applicant to evaluate the passivation performance of water, ethanol, methanol, dimethoxyethane (DME), n-pentane, acetonitrile and cyclic-ether (THF).

[0272] Samples of pyrophoric Ti metal particles and the above liquors were prepared and tested in accordance with the procedure described in the preceding section: [0273] 1. Liquor contact, no pressure, not air exposure. [0274] 2. Liquor contact, no pressure, air exposure. [0275] 3. Liquor contact, pressure, not air exposure. [0276] 4. Liquor contact, pressure, air exposure. [0277] 5. Baseno liquor, no pressure, no air exposure

[0278] A selection of the results of the test work is summarised in FIGS. 3-14. The Figures report the following results for each liquor: [0279] (a) oxygen uplift of test protocols 1-4 above compared to the base case 5 (i.e., no liquor, air exposed, and no pressure); and [0280] (b) chloride uplift for test protocols 1-4 above and base case 5 (not for n-pentane and acetonitrile).

[0281] FIGS. 3 and 4 show the results for ethanol. FIGS. 5 and 6 show the results for THF. FIGS. 7 and 8 show the results for methanol. FIGS. 9 and 10 show the results for water. FIGS. 11 and 12 show the results for DME. FIG. 13 shows the results for oxygen uplift for n-pentane. FIG. 14 shows the results for oxygen uplift for acetonitrile.

[0282] Ethanol had one of the lowest oxygen uplifts from the base pyrophoric Ti metal particles 469 ppm oxygen uplift.

[0283] In addition, the ethanol results for chloride indicate that passivated Ti metal particles had one of the lowest chloride levels at 144 ppm.

[0284] THF had a lower oxygen uplift at 413 ppm than ethanol, but it results in passivated Ti metal particles with residual chloride levels at 242 ppm.

[0285] The oxygen uplifts with water and methanol are higher than for ethanol and methanol. The residual chloride levels are comparable to that for ethanol.

[0286] In all cases, the oxygen uplifts are within customer specifications known to the applicant.

[0287] The results also show that the extent of oxygen uplift can be controlled with liquor selection and exposure time. The exposure time point was evident from other results not reported here.

[0288] With regard to oxygen, as noted above, oxygen concentration in passivated pyrophoric Ti metal and Ti alloy particles is an important consideration.

[0289] Physical and mechanical properties of Ti metal change significantly with small changes of oxygen (100's to 1000's ppm). For this reason, standard specifications and customer requirements have formed around products with controlled levels of oxygen to achieve reproducible and reliable mechanical properties. The ability to control the oxygen content of particles of Ti metal and Ti alloys within the ranges of relevant customer requirements and industry standards after they have been formed is therefore highly valuable.

Test Work Summary

[0290] In summary, the above test work shows that ethanol, methanol, water, THF, n-pentane, acetonitrile, and DME can effectively passivate pyrophoric Ti metal particles and reduce chloride levels in pyrophoric Ti metal particles. These are significant findings.

[0291] It is noted that test work was conducted by the applicant at elevated temperatures (as well as ambient temperatures for the above test work), and particles tested were successfully passivated.

[0292] In addition, the test work carried out by the applicant indicates that similar results can be obtained with pyrophoric Ti alloys, such as Ti64.

General Comments

[0293] The applicant has carried out fundamental research work and the above-described and further test work.

[0294] Whilst not wishing to be bound by the following comments, the applicant believes that the observed passivation is due to passivation components of the liquors tested forming passivated protective layers with Ti on the surfaces of particles of pyrophoric Ti metal and Ti alloys.

[0295] In the case of the test work reported above, the passivation components are oxygen, nitrogen and hydrocarbons.

[0296] An important observation is that these passivation components and exposure conditions can be selected so that there is no significant contamination (for example by chlorides) of the passivated pyrophoric Ti metal and Ti alloy particles. This is important for many end-use applications.

[0297] Many modifications may be made to the embodiment described above in relation to FIG. 1 without departing from the spirit and scope of the invention.

[0298] By way of example, whilst FIG. 1 describes an embodiment of the process and apparatus of the invention that produces air-stable, passivated, i.e., non-pyrophoric, particles of a pyrophoric material with low concentrations of contaminants, the invention is not confined to reducing contaminant concentrations.

[0299] In other words, the invention includes embodiments that passivate particles of a pyrophoric material so that they become passivated, i.e., non-pyrophoric, as measured by industry and customer standards, with or without reducing the concentration of contaminants in the pyrophoric material.

[0300] In addition, whilst FIG. 1 describes an embodiment of the process and apparatus of the invention in the context of MgCl.sub.2 as a contaminant, the invention is not confined to this contaminant.

[0301] In addition, whilst FIG. 1 describes an embodiment of the process and apparatus of the invention in the context of a liquor, the invention also extends to the use of suitable gases and vapours.