NZ567533A - Fluorine treatment of titanium materials to produce titanium dioxide - Google Patents

Abstract

Disclosed is a process for the treatment of titanium materials, wherein the process includes: (a) reacting ammonium bifluoride with the material at the molar ratio (2.5-6.5) : 1 at 50-190 Deg. C to form a fluorinated mass and (b) heating the fluorinated mass in two stages: (i) the first stage involves heating the fluorinated mass to 220-300 Deg. C to form a reaction mixture and volatilised ammonium fluosilicate and then extracting the volatilised ammonium fluosilicate and chemically separate silicon dioxide from the volatilised ammonium fluosilicate, (ii) the second stage involves further heating the reaction mixture in oxygen-free conditions to 300-600°C to sublimate the titanium compounds and further hydrolyse them to produce titanium dioxide, wherein the titanium dioxide obtained has a purity of at least 99.98%.

Description

567533 Patents Form # 5 *10055477690* DIVISIONAL OUT OF APPLICATION # 543193 ANTE-DATING REQUESTED TO 25 October 2005 NEW ZEALAND Patents Act 1953 5675 33 COMPLETE SPECIFICATION Title F-Treatment of Titanium Materials We, INNOVATIVE WATER SOLUTIONS LIMITED Address: PO Box 7041, New Plymouth, New Zealand INTELLECTUAL PROPERTY OFFICE OF N.2. 18 APR 2008 received! Nationality A New Zealand company do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: 400210>IZA_Drvpat_20080417_2050_TGR.doc400210NZA_Divpat_20080417_2050_TGR.doc FEE CODE - 1010 567533 F-Treatment of Titanium Materials Field of Invention The invention relates to a continuous process for the fluorine treatment of titanium bearing 5 materials such as ilmenite, titano-magnetite, etc, to produce a high purity end product such as super fine grade titanium dioxide, silicon dioxide and also as an integral part of the recovery of precious and/or valuable metals/minerals.

Background of Invention The extraction of metallic materials from sand, ore or the like can be an expensive and labour intensive task. However as the value and demand for these metallic materials increases the extraction of these metallic materials becomes more viable.

Of these metallic materials, titanium based materials is widely sought after. More than 80% 15 of Ti02 produced worldwide is used as a paint pigment. Also it is widely used as an ingredient of the heat-resistant glass, ceramics, in metallurgy and electronics, cosmetics, as well as in manufacturing of toners for photocopying. Ilmenite is the main raw material for the production of titanium dioxide.

The unique properties of Ti and its derivatives are well known. A major limitation that - withholds the widespread application of these materials is its high cost.

The bulk amount of TiC>2 is produced via digestion of ilmenite with sulphuric acid. This method, however, has serious drawbacks such as high cost, hazards related to handling 25 concentrated sulphuric acid, environmental aspects associated with chemical waste recovery and disposal, complexity due to multi-stage operation and also limitations related to the quality of raw materials.

Fluorine-based methods are more efficient in processing ilmenite. There are two publications 30 having close relation to this invention, namely Russian patents RU 2058408 and RU 2136771).

C:\WorkTemp\400210NZ\400210NZ_COMPSPEC_20061020.doc 567533 Both methods utilise the flourination of the titanium-bearing material with ammonia bifluoride NH4HF2 producing fluoammonium salts (complex salts) of titanium, silicon and iron. The obtained complex salts are then heat-treated in air, causing sublimation of the volatile fluorides of titanium and silicon, the latter being separated either using the difference 5 in partial pressure values at the temperature of volatilization, or by means of pyrolytic hydrolysis of ammonium fluotitanate.

These disclosed methods have the following drawbacks: ■ as a result of simultaneous sublimation of titanium and silicon (in the form of their complex salts), the latter contaminates the end product or otherwise introduces additional stages to the process, thus making it less cost efficient; ■ sublimation of the complex salts in the presence of oxygen (air) leads to incomplete volatilization of titanium and also contaminates the sublimate with titanium oxofluorides, the latter causing deterioration of the quality of an end product or necessity of additional treatment; ■ sublimation of the complex salts causes partial losses of iron to the sublimate due to gas-transport reaction within the system, what consequently ends up with contamination of an end product with iron oxides.

Object of the Invention It is an object of the invention to provide a continuous process for the fluorine treatment of metallic bearing materials, including titanium-bearing materials, that ameliorates some of the disadvantages and limitations of the known art or at least provide the public with a useful 25 choice.

Summary of Invention.

In a first aspect the invention resides in a process for the treatment of titanium materials, 30 wherein the process includes: a) reacting the material with ammonium bifluoride at 50-190°C to form a fluorinated mass, and b) heating the fluorinated mass in two stages: C:\WorkTemp\400210NZV400210NZ_COMPSPEC_20061020.doc 567533 i) the first stage involves heating the fluorinated mass to 220-300°C to form a reaction mixture and volatilised ammonium fluosiiicate and then extracting the volatilised ammonium fluosiiicate and chemically separate silicon dioxide from the volatilised ammonium fluosiiicate, 5 ii) the second stage involves further heating the reaction mixture to 300- 600°C to sublimate the titanium compounds and further hydrolyse them to produce titanium dioxide.

Preferably, ammonium bifluoride is added to the titanium material at the molar ratio (2.5-10 6.5) :1.

Preferably, the molar ratio is (2.5-4.0) : 1.

Preferably, the reacting the material with ammonium bifluoride at a temperature between 15 160-180°C.

Preferably, the reacting the material with ammonium bifluoride is complete within 0.5-6 hours.

Preferably, the reacting the material with ammonium bifluoride is complete within 0.5-10 hours.

Preferably, the first stage heating is kept within a temperature range of 225-245 °C in order to achieve sublimation of ammonium fluosiiicate from the fluorinated mass.

Preferably, the extracted volatilised ammonium fluosiiicate is fed to a condenser to solidify before being chemically separated in a separator.

Preferably, the solid ammonium fluosiiicate is treated with an ammonium solution to form 30 silicon dioxide precipitate.

Preferably, the silicon dioxide precipitate obtained has a purity of at least 99.99%.

C:\WorkTemp\400210NZ\400210NZ__C01MPSPEC_20061020.doc 567533 Preferably, the reaction mixture is heated to a temperature between 540-580 °C.

Preferably, an inert gas is supplied during the second stage to ensure the oxygen-free condition of the reaction mixture.

Preferably, hydrogen gas is fed during the second stage to ensure reduction of the metallic fluorides to their metallic form.

Preferably, the formed metal is separated and extracted from the titanium compounds.

Preferably, the formed metal is iron.

Preferably, a non fluorinated and non volatile residue formed as a result the sublimation of the reaction mixture to the titanium compounds is separated and extracted from the titanium 15 compounds.

Preferably, non fluorinated and non volatile residue is further refined to extract thereform any precious metals or any other suitable metals.

Preferably, the second stage is complete within 2-5 hours.

Preferably, the titanium compound is volatilised ammonium fluotitanate.

Preferably, the volatilised ammonium fluotitanate is fed to a condenser-hydrolyser where it 25 undergoes pyrolytic hydrolysis to produce titanium dioxide.

Preferably, the titanium dioxide is produced in a crystalline form.

Preferably, the crystalline titanium dioxide obtained has a purity of at least 99.98%.

Preferably, the titanium material is a titanium bearing ore or sand.

Preferably, the titanium bearing ore or sand is ilmenite or tiano-magnetite.

C:\WorkTemp\400210NZ\400210NZ_COMPSPEC_20061020.doc 567533 Preferably, the hydrolysis of the titanium compounds occurs in two steps, these steps being: i) passing the titanium compounds into a condenser in order to condense the titanium compounds, and ii) hydrolysing the titanium compound condensate to produce titanium dioxide.

Preferably, the hydrolysing of the titanium compound condensate involves adding an ammonia solution.

In a second aspect the invention resides in a method of processing the minerals in any form (liquid, gaseous or solid) aimed at simultaneous extraction of other valuable products (Au, Pt, Pd, Ag, Sc etc), consists of the following stages: i) preparation of the raw material (crushing, grinding, sizing, etc of the ore); ii) thermal oxidation at elevated temperatures to destroy the mineral lattice; iii) adding fluorine source to the raw material (Hydrofluoric Acid, Ammonia Bifluoride, etc.); iv) fluorination at elevated temperature (preferably below 200°C), producing as a result complex salts (e.g. ammonia fluosiiicate) and non-fluorinated materials; v) sublimation of the volatile complex salts at the temperatures above 200°C followed by condensation and hydrolysis of sublimate to produce high purity oxides of Si, Ti, etc; vi) reduction of ferrous fluoride to form iron metal; vii) separation of iron metal from residue using magnetic or any other type separator, the residue containing precious metals, non-volatile metallic fluorides and other non-fluorinated matter; viii) second fluorination with ammonium bifluoride to convert metal fluorides into ammonium fluometallates; ix) hydration followed by separation of soluble ammonium fluometallates from residue using any existing method (precipitation, filtration, etc.); x) extraction of precious and rare earth metals from residue by means of leaching, electrowinning, flotation, etc; xi) smelting precious metals followed by their refinery.

C:\WorkTemp\400210NZVl00210NZ_COMPSPEC_20061020.doc 567533 In a third aspect the invention resides in an apparatus for the treatment of titanium materials wherein the apparatus includes: a) a fluorination reactor in which the material is mixed with and reacts with ammonium bifluoride, wherein the flourination reactor is adapted to be heated to a temperature between 5 0-190°C to initially form a fluorinated mass and then adapted to cause the fluorinated mass to be heated to a temperature between 220-3 00°C to form a reaction mixture and volatilised ammonium fluosiiicate; b) a condenser connected to the fluorination reactor, wherein the condenser is adapted to extract the volatilised ammonium fluosiiicate from the fluorination reactor and condense the volatilised ammonium fluosiiicate to a solid form; c) a first separator connected to the condenser, wherein the separator is adapted to extract the solid form of ammonium fluosiiicate and separate thereform silicon dioxide; d) a reactor sublimator connected to the fluorination reactor, wherein the reactor sublimator is adapted to extract the reaction mixture from the fluorination reactor and heat the reaction mixture to a temperature between 300-600°C to reduce iron to form iron metal and sublimate reaction mixture to form titanium compounds and residue; and e) a condenser-hydrolser adapted to receive the titanium compounds from the reactor sublimator and adapted to hydrolyse the titanium compounds to produce titanium oxide.

Preferably, the apparatus has a second separator connected to the reactor sublimator, wherein the second separator is adapted to extract from the reactor sublimator the residue and separate therefrom pure metal.

In a fourth aspect of the invention resides in a process for the treatment of titanium materials, wherein the process includes: a) reacting the material with ammonium bifluoride at 50-190°C to form a fluorinated mass, and b) heating the fluorinated mass to 220-300°C to form a reaction mixture and volatilised ammonium fluosiiicate and then extracting the volatilised C:\WorkTemp\400210NZ\400210NZj:OMPSPEC_20061020.doc 567533 ammonium fluosiiicate and chemically separate silicon dioxide from the volatilised ammonium fluosiiicate in order to obtain a silica precipitate.

In other aspects herein described Brief Description The invention will now be described, by way of example only, by reference to the accompanying drawings: Figure 1 is a process flow diagram in accordance with a preferred embodiment of the invention.

Figure 2 is a process flow diagram in accordance with a further preferred embodiment of the invention Description of Drawings The following description will describe the invention in relation to preferred embodiments of the invention. The invention is in no way limited to these preferred embodiments as they are purely to exemplify the invention only and that possible variations and modifications would 20 be readily apparent without departing from the scope of the invention.

Ground titanium-bearing ore or sand (ilmenite, titano-magnetite, etc.) is mixed with crystalline, molten or dissolved ammonim bifluoride at the molar ratio 1: (2.5-6.5), respectively. The generalized equation of fluorination for ilmenite can be presented as 25 follows: FeTiOs + 6.5 NH4HF2 + 0.25 02 (NH^FeFg + (NH^TiFy + 3.5 H20 + 0.5 NH3 The chosen molar ratio of components, however, ensures lesser saturation of the complex 30 fluoammonium salts with ammonium fluoride, as compared with shown stoichiometry. This facilitates the completion of the reaction within 0.5 - 10 hours. Any ratios below 2.5 moles of ammonium bifluoride per 1 mole of the titanium-bearing material would result in incomplete volatilisation of ammonium fluotitanates at the sublimation stage.

C:\WorkTemp\400210NZ\400210NZ_COMPSPEC^20061020. doc 567533 Fluorination of silicon dioxide, which is typically present in ilmenite, leads to formation of its fluoammonium salt according to the following reaction: Si02 + 3NH4HF2 (NH^a SiF6 + 2 H20 + KH3 Ammonia and steam evolved from the reaction zone are used for the hydrolysis of ammonium fluosiiicate and also to absorb the acidic fluoride vapours for ammonium bifluoride recovery and reuse in the process. Additional heat produced in the course of this 10 reaction, might lower the temperature of the beginning of fluorination.

Obviously, a major and current problem in separation of titanium, silicon, iron and other metals derived from a natural source, is cross-contamination which can effect the obtaining of high-purity end products. This problem could be resolved possibly at the very beginning 15 of the process, which would greatly simplify the process and make the technology cost-efficient. Therefore, the present invention deploys separation of the said elements before sublimation, using differences in their physico-chemical properties.

Ammonium fluosiiicate can be easily volatilised within a temperature range between 220 and 20 300°C. Under these conditions ammonium fluotitanate has negligibly low partial pressure, thus ensuring easy separation of silicon from the other two elements present in the titanium bearing ore. The volatilised ammonium fluosiiicate is then condensed at lower temperatures, followed by hydrolysis and subsequent precipitation of silicon dioxide as follows: (NH4)2 SiF6 + 2 H20 + NHj -> Si02 + 2 NH3 + 6 HF A high quality of hydrated silica (99.99% purity) is obtained.

The remaining fluorinated mass consisting of the complex fluoammonium salts of titanium, 30 iron and other trace metals, undergo pyrolytic decomposition while temperature rises from 300 to 600 °C, according the following scheme: (NH4)3TlF7(NH4)2TiF6-> NH4TiF5 -» TiF4 C:\WorkTemp\4OO2iONZ\4OO2iONZ__COMPSPEC_2OO6IO2O.doc 567533 This causes the release of fluoride and ammonia that are then further reused in the process.

Presence of any significant amount of oxygen (air) in the reactor results in the formation of 5 ammonium oxofluotitanate: (NH4)2TiF6 + H20 (NftOo.sTiOFzs + 1.5 NH3 + 3.5 HF The pyrolytic decomposition of this compound yields in formation of oxofluotitanates 10 TiO„Fm (yellow colour) that may affect the quality of the target titanium dioxide and/or considerably complicate the scheme due to necessity of inclusion additional treatment/purification stages. Therefore, it is critical to carry out the high-temperature sublimation in airtight conditions and/or in the atmosphere of an inert gas.

Although the volatility of ferrous fluoride is negligible at below 600°C, there is a potential of contamination of sublimate with iron and/or other trace metals due to its loss to gaseous phase during the high rate gas-transport reaction of sublimation. However this can be overcome by the addition of hydrogen gas or other reductant to reduce for example the ferrous fluoride producing iron metal in a powdered form, as follows: FeF2 + 3 H2 —> Fe + 6 HF The reduced iron completely eliminates the probability of its losses with sublimate. Additionally this gives an advantage of producing another valuable pure iron metal. Iron can 25 be mechanically separated from other impurities or otherwise used as a commercial product for metallurgy (other ingredients are fluorides of calcium and magnesium - these are used as anti-friction components). Another invaluable advantage is that the surplus amounts of fluoride liberated in the course of this reaction creates an atmosphere favourable for more complete extraction of titanium from ilmenite, thus allowing considerable shortening of the 30 initial fluorination and saving on equipment and ammonium bifluoride.

A non-fluorinated and non-volatile residue is formed as a result the sublimation of the reaction mixture to the titanium compounds and this residue is separated and extracted from C:\WorkTemp\4OO2iONZ\4OO2iONZ_eOMPSPEC_2OO6lO2O.doc 567533 - n - the titanium compounds. The non-fluorinated and non-volatile residue is further refined to extract therefrom any precious metals or any other suitable metals such as Au, Pt, Sc, Lu, etc.

Eventually, the sublimated fluorides enter the last compartment where titanium undergoes hydrolysis according to its reaction with water: TiF4 + 2 H20 -» Ti02 + 4 HF The resultant titanium dioxide precipitates on the reactor walls in the form of snow-white fine crystals.

The hydrolysis of titanium compounds can be carried out either pyrolytically at elevated temperatures, according its reaction with steam or, alternatively, in two steps, these steps 15 being: i) passing the titanium compounds in a condenser in order to condense the titanium compounds, and ii) hydrolysing the titanium compound condensate to produce titanium dioxide.

Ammonium fluoride evolved from different stages of the process, is mixed with ammonia solution, which is then evaporated and after crystallization reused at the fluorination stage.

A preferred method of the invention will now be described in association with figure 1 which is a process flow diagram illustrating the preferred process of the fluorine treatment of 25 titanium materials into titanium oxide..

Ammonium bifluoride is gradually added to ilmenite or titano-magnetite at the molar ratio of (2.5-4.0): 1. This minimises the viscosity of the composite mass, thus improving mixing and mass-transfer conditions in the fluorination reactor (F-reactor) 10. The reaction is complete 30 within 0.5 - 6 hours, at the temperature between 120 and 190°, preferably 160-180°C. On heating above 190°C ammonia bifluoride vaporizes. Factors affecting the duration of fluorination are the temperature, mass ratio and fraction size of components. The reaction is complete when no more ammonia and steam are evolved from the reaction zone.

C:\WorkTemp\400210NZ\400210NZ_COMPSPEC_20061020.doc 567533 The sublimation of ammonium fluosiiicate in the F-reactor 10 starts after the temperature is increased and kept within a range from 220 to 300°C, preferably 225-245°C. Any values above 300°C may lead to contamination of the sublimate with titanium. The volatilised 5 ammonium fluosiiicate is fed to a condenser 11 where it solidifies at 20 to 220°C. The condensed product is then transferred to a separator 12 to be treated with ammonia solution, followed by precipitation and further separation of silicon dioxide 13 by either filtration, drying, etc.

All the off-products including ammonia, ammonium fluoride and steam, are withdrawn and diverted to the ammonium bifluoride recovery system for further reuse in the process. The ammonia can also be reused to produce pure silica.

The solid discharge from the F-reactor 10 consists of the complex fluoammonium salts of 15 titanium, iron together with quantities of other metal flourides (Ca, Mg, Na, etc.) and oxides, plus a quantity of unreacted ilmenite. This solid discharge is transferred to a reactor-sublimator 14 where the fluorinated mass is indirectly heated to 300-600 °C, preferably to 540-580°C, with simultaneous feed of hydrogen or its mixture with inert gas (nitrogen, argon, etc.) into the reaction zone. The amount of hydrogen fed to reactor should be between 20 50 and 100 percent from stoichiometric requirement. This ensures reduction of ferrous fluoride to iron metal, release of additional hydrogen fluoride and, thus, digestion of unreacted ilmenite. The reaction is complete within 2-5 hours.

The solid discharge from the reactor-sublimator 14 containing iron metal, other metals, other 25 oxides and unvolatilized fluorides of calcium and magnesium undergo magnetic separation in a separator 15 to produce powdered iron 16 and residue 19. A non-fluorinated and nonvolatile residue 19 is formed as a result of the sublimation of the reaction mixture to the titanium compounds and this residue 19 is extracted from the titanium compounds and separated in separator 15 from iron. The non-fluorinated and non-volatile residue 19 is able 30 to be further refined to extract therefrom any precious metals or any other suitable metals such as Au, Pt, Ag, Pd, etc.

C:\WorkTemp\400210NZ\400210NZ_COMPSPEC_20061020.doc 567533 The volatilised ammonium fluotitanate together with other gases is then fed to a condenser-hydrolyzer 17 where steam is also added; the temperature of this reaction is kept within 300-600 °C. As a result, titanium undergoes pyrolytic hydrolysis to form crystalline titanium dioxide 18 precipitating on the walls of this reactor.

Or alternatively hydrolysis of the titanium compounds can also occur in two steps, these steps being: i) passing the titanium compounds in a condenser 17A in order to condense the titanium compounds, and 10 ii) hydrolysing the titanium compound condensate in a separator 17B to produce and extract titanium dioxide 18A.

The above process even though described in relation to the obtaining of titanium oxide can be readily applicable to the extraction of other valuable and/or precious metals and minerals 15 such as Au, Pt, Sc, Lu, from sand, ore, or the like. consists of the following stages: preparation of the raw material (crushing, grinding, sizing, etc of the ore); thermal oxidation at elevated temperatures to destroy the mineral lattice; adding fluorine source to the raw material (Hydrofluoric Acid, Ammonia Bifluoride, etc.); fluorination at elevated temperature (preferably below 200°C), producing as a result complex salts (e.g. ammonia fluosiiicate) and non-fluorinated materials; sublimation of the volatile complex salt at the temperatures above 200°C followed by condensation and hydrolysis of sublimate to produce high purity oxides of Si, Ti, etc; reduction of ferrous fluoride to form iron metal; separation of iron metal from residue using magnetic or any other type separator, the residue containing precious and rare earth metals, non-volatile metallic fluorides and other non-fluorinated matter; second fluorination with ammonium bifluoride to convert metal fluorides into ammonium fluometallates; C:\WorkTemp\400210NZ\400210NZ_COMPSPEC_20061020.doc The process i) ii) iii) iv) v) vi) vii) viii) 567533 ix) hydration followed by separation of soluble ammonium fluometallates from residue using any existing method (precipitation, filtration, etc.); x) extraction of precious metals from residue by means of leaching, electrowinning, flotation, etc; xi) smelting precious metals followed by their refinery.

Turning to figure 2 which shows a process flow chart incorporating the the process described in figure 1, but which further includes a preferred process for the recovery of precious metals and/or minerals such as Au, Pt, Pd, Ag, etc.. Ground ore or sand is passed through a 10 separation unit 30 to separate a target fraction from tailings. The target fraction undergoes thermal oxidation and is then passed to a fluorination treatment unit 31 where precious metals and metal fluorides are separated from volatile silicon compounds. The silicon compounds are then passed through a condensation-separation unit 32 so as to obtain silicon dioxide. The precious metals and metal fluorides are then passed through a reduction-15 sublimation unit 33 from which titanium compounds are extracted and passed through a separator reduction-sublimation unit 3 3A. The iron, precious metals and metal fluorides is then passed through a separator 34 in order to separate iron from the precious metals and metal fluorides. The precious metals and metal fluorides are then passed through another fluorination treatment step 35 so as to form ammonia fluometallates and precious metals 20 mixture. The ammonia fluometallates and precious metals are passed through a separator 36 to form and separate ammonia fluotitanates 39 from the precious metals mixture. The precious metals mixture is then passed through an extraction unit 37 to extract therefrom non-fluorinated residue 40. The precious metals are then refined in a refining unit 38 in order to refine and obtain the precious metals.

Advantages ■ The proposed method allows manufacture high purity (> 99.98%) fine grade titanium dioxide with exceptional whiteness; ■ Along with the main product - titanium dioxide, other valuable products can be 30 obtained, such as high purity silicon dioxide (>99.99%) and metals such as iron; ■ Method ensures substantial saving (up to 30-35%) on active ingredients, such as ammonium bifluoride, as a result of additional fluorination of the source material C:\WorkTemp\400210NZ\400210NZ_COMPSPEC_20061020.doc 567533 with fluoride released from iron reduction; therefore, the duration of fluorination is considerably shortened (1,5-2 times); ■ Capital (equipment and space) saving achieved due to elimination of stages related to calcination of an end product and also separation of the target elements after sublimation; ■ Proposed method has no waste or undesirable by-products, what makes it environmentally attractive and cost-efficient.

Variations Throughout the description of this specification, the word "comprise" and variations of that word such as "comprising" and "comprises", are not intended to exclude other additives, components, integers or steps.

It will of course be realised that while the foregoing has been given by way of illustrative example of this invention, all such and other modifications and variations thereto as would be apparent to persons skilled in the art are deemed to fall within the broad scope and ambit of this invention as is hereinbefore defined in the appended claims.

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Claims (32)

567533 -16- VV1IA1 WE CLAIM IS:

1. A process for the treatment of titanium materials, wherein the process includes: a) reacting ammonium bifluoride with the material at the molar ratio (2.5-6.5): 1 at 50-190°C to form a fluorinated mass and b) heating the fluorinated mass in two stages: i) the first stage involves heating the fluorinated mass to 220-300°C to form a reaction mixture and volatilised ammonium fluosiiicate and then extracting the volatilised ammonium fluosiiicate and chemically separate silicon dioxide from the volatilised ammonium fluosiiicate, ii) the second stage involves further heating the reaction mixture in oxygen-free conditions to 300-600°C to sublimate the titanium compounds and further hydrolyse them to produce titanium dioxidef wherein the titanium dioxide obtained has a purity of at least 99.98%.

2. The process as claimed in claim 1 wherein the molar ratio is (2.5-4.0): 1.

3. The process as claimed in claim 2 wherein the reacting the material with ammonium bifluoride at a temperature between 140-180°C.

4. The process as claimed in claim 2 wherein the reacting the material with ammonium bifluoride is complete within 0.5-6 hours.

5. The process as claimed in claim 2 wherein the reacting the material with ammonium bifluoride is complete within 0.5-10 hours.

6. The process as claimed in claim 5 wherein the extracted volatilised ammonium fluosiiicate fed to a condenser to solidify before being chemically separated in a separator.

7. The process as claimed in claim 6 wherein the solid ammonium fluosiiicate is treated with an ammonium solution to form silicon hydroxide precipitate. I:\400200\400210NZA\400210NZ FINALAmeildedCOMPSPEC 20090915.doc 567533 - 17-

8. The process as claimed in claim 7, wherein the silicon hydroxide precipitate is heat treated to form silicon dioxide.

9. The process as claimed in claim 8 wherein the silicon dioxide precipitate obtained 5 has a purity of at least 99.99%.

10. The process as claimed in anyone of the preceding claims wherein the reaction mixture is heated to a temperature between 540-580°C. 10

11. The process as claimed in claim 10, wherein an inert gas is supplied during the second stage heating to ensure the oxygen-free condition of the reaction mixture.

12. The process as claimed any one of claims 10 to 11, wherein hydrogen gas is fed during the second stage to ensure reduction, of the metallic fluorides to their metal form. 15

13. The process as claimed in claim 12, wherein the formed metal is separated from the titanium compounds.

14. The process as claimed in claim 13, wherein the formed metal is iron. 20

15 The process as claimed in claim 14, wherein a non fluorinated and non volatile residue formed as a result of the sublimation of the reaction mixture to the titanium compounds is separated and extracted from the titanium compounds. 25

16 The process as claimed in claim 15, wherein the non fluorinated and non volatile residue is further refined to extract therefrom any precious metals or any other suitable metals.

17. The process as claimed in any one of the preceding claims wherein the second stage 30 is complete within 2-5 hours.

18. The process as claimed in any one of the preceding claims wherein the titanium compound is volatilised ammonium fluotitanate. I:\400200\400210NZA\400210NZ FrNALAmendedCOMI'SPEC 20090915.doc 567533 -18-

19. The process as claimed in claim 18, wherein the volatilised ammonium fluotitanate is fed to a condenser-hydrolyser where it undergoes pyrolytic hydrolysis to produce titanium dioxide. 5

20. The process as claimed in claim 19, wherein the titanium dioxide is produced in a crystalline form.

21. The process as claimed in any one of the preceding claims wherein the titanium 10 material is a titanium bearing ore or sand.

22. The process according to claim 21, wherein the titanium bearing ore or sand is ilmenite or tiano-magnetite. 15

23. The process as claimed in any one of the claims 1 to 18, wherein the hydrolysis of the titanium compounds occurs in two steps, these steps being: i) passing the titanium compounds in a condenser in order to condense the titanium compounds, and ii) hydrolysing the titanium compound condensate to produce titanium dioxide. 20

24. The process as claimed in claim 23, wherein the hydrolysing of the titanium compound condensate involves adding an ammonia solution.

25. The process as claimed in claim 12 wherein a non-fluorinated and non-volatile 25 residue formed as a result of the sublimation of the reaction mixture to the titanium compounds is separated and extracted from the titanium compounds.

26. The process as claimed in claim 25 wherein the non-fluorinated and non-volatile residue is further refined to extract therefrom any precious metals or any other suitable 30 valuables.

27. A process for the treatment of titanium materials, wherein the process includes: l:\400200\4002iONZAV400250NZ FiNALAmendedCOMPSPEC 20090915.doc 567533 - 19- a) reacting ammonium bifluoride with the material at the molar ratio (2.5-6.5) : 1 at 50-190°C to form a fluorinated mass, and b) heating the fluorinated mass to 220-300°C to form a reaction mixture and volatilised ammonium fluosiiicate and then extracting the volatilised 5 ammonium fluosiiicate and chemically separate silicon dioxide from the volatilised ammonium fluosiiicate in order to obtain a silica precipitate, wherein the silica precipitate obtained has a purity of at least 99.99%..

28. An apparatus for the treatment of titanium materials wherein the apparatus includes: 10 a) a fluorination reactor in which the material is mixed with and reacts with ammonium bifluoride, wherein the fluorintion reactor is adapted to be heated to a temperature between 50-190°C to initially form a fluorinated mass and then adapted to cause the fluorinated mass to be heated to a temperature between 220-300°C to form a reaction mixture and volatilised ammonium 15 fluosiiicate; b) a condenser connected to the fluorination reactor, wherein the condenser is adapted to extract the volatilised ammonium fluosiiicate from the fluorination reactor and condense the volatilised ammonium fluosiiicate to a solid form; c) a first separator connected to the condenser, wherein the separator is adapted 20 to extract the solid form of ammonium fluosiiicate and separate therefrom silicon dioxide; d) a reactor sublimator connected to the fluorination reactor, wherein the reactor sublimator is adapted to extract the reaction mixture from the fluorination reactor and heat the reaction mixture to a temperature between 300-600°C to 25 sublimate reaction mixture to form titanium compounds and residue; and e) a condenser-hydrolser adapted to receive the titanium compounds from the reactor sublimator and adapted to hydrolyse the titanium compounds to produce titanium oxide. 30

29. The apparatus as claimed in claim 28, wherein the apparatus has a second separator connected to the reactor sublimator, wherein the second separator is adapted to extract from the reactor sublimator the residue and separate therefrom pure metal. I :\400200\40021 ON7.A\400210NZ FiNALAmendedCOMPSPEC 20090915.doc 567533 -20-

30. A process for the treatment of metallic bearing materials as hereinbefore described with reference to figure 1.

31. A process for the treatment of titanium materials as hereinbefore described with 5 reference to figure 1.

32. An apparatus for the treatment of titanium materials as hereinbefore described with reference to figure 1. 10 PIPERS 15 Attorneys for the Applicant I:\400200\4Q02IONZA\400210NZ FiNALAmendedCOMPSPEC 20090915.doc