WO2014125275A1

WO2014125275A1 - Method for producing titanium oxide and iron oxide

Info

Publication number: WO2014125275A1
Application number: PCT/GB2014/050409
Authority: WO
Inventors: Stephen J. SUTCLIFFE; Stuart W. JOHNSON
Original assignee: Tioxide Europe Limited
Priority date: 2013-02-15
Filing date: 2014-02-12
Publication date: 2014-08-21
Also published as: TW201437382A; GB201302726D0

Abstract

The invention relates to a method for producing titanium oxide from an iron-titanium ore, with co-production of iron oxide. The method comprises providing an iron- titanium ore that comprises from 40 to 65wt% TiO₂ and from 30 to 55wt% iron species;upgrading the iron-titanium ore by treating it with a leach liquor comprising hydrochloric acid, to produce a solid phase of upgraded titania material and a spent liquid phase comprising dissolved metal chlorides, wherein the upgraded titania material contains 75wt% or more TiO₂; separating the solid phase from the spent liquid phase; and reacting the metal chlorides dissolved in the spent liquid phase in the presence of oxygen to produce hydrochloric acid and iron oxide, with the reaction being carried out in a fluid bed reactor so as to provide the iron oxide in sintered form. The method may further comprise converting the upgraded titania material to titanium tetrachloride or titanium metal.

Description

METHOD FOR PRODUCING TITANIUM OXIDE AND IRON OXIDE

Field of the Invention The present invention relates to a method for producing titanium oxide from an iron- titanium ore, with co-production of iron oxide in a form that can be directly useful rather than in waste form. In particular, the invention relates to a method for producing titanium oxide, from an iron-titanium ore that has a relatively high iron content and relatively low titania content, with co-production of useful iron oxide. The titanium oxide can be used directly or can subsequently be used to form other useful products such as titanium tetrachloride or titanium metal. The iron oxide can be subsequently used in a process for the manufacture of iron and/or steel e.g. in a blast furnace. Background to the Invention

In the commercial manufacture of titanium tetrachloride, a titaniferous material is chlorinated in the presence of carbonaceous material (usually coke) as a reducing agent, conventionally in a fluid bed reactor. Titaniferous materials (i.e. those materials that contain or yield titanium) are well known and include ilmenite, anatase, leucoxene, slag, synthetic rutile and natural rutile . In general, the titaniferous material used in such processes will have a relatively high percentage of titania, for example the Ti0₂ content may be 85wt% or higher. In such a manufacturing process, the titaniferous material is maintained in a reactor in a fluid suspension by the passage therethrough of the reactant gas chlorine . The reducing agent is mixed with the material and chlorination is effected at an elevated temperature to produce gaseous titanium tetrachloride as part of the product stream. The product stream from the chlorinator includes the desired titanium tetrachloride and chlorides of impurities in the titaniferous material, together with "blowover" ore and coke solids and with various by-product gases such as carbon monoxide, carbon dioxide and the like . After passing through a heat exchanger, quench or the like to cool down the chlorinator product stream, the metal chlorides apart from titanium chloride are condensed from the gas stream as solid particles enter into a gas/solids separator, typically in the form of a cyclone separator. Such a separator will remove certain metal chlorides from the gas stream together with unreacted titanium ore and carbon dust in the form of a residue . Processes for chlorinating titanium-containing materials are known from, for example, US 4 244 935, US 3 895 097, US 2 701 179, US 3 883 636, US 3 591 333, and US 2 446 181.

The production of synthetic rutile, suitable for use in such a process, is also known. Synthetic rutile, also known as beneficiated ilmenite or upgraded ilmenite, can be obtained by a number of processes.

One known process produces synthetic rutile from titaniferous ores, in particular ilmenite, by beneficiation with hydrochloric acid. This beneficiation process is described in, for example, US 3 825 419. Such processes essentially involve extracting or leaching iron and other acid-soluble constituents from the ore, leaving a solid "synthetic rutile" product having high titanium dioxide content and low iron content.

A process was described in US 4 435 365 that involves using an acid leaching process to upgrade an iron-titanium ore, e.g. to produce synthetic rutile from ilmenite, prior to carrying out a chlorination step on that upgraded ore, to obtain titanium tetrachloride . Dissolved metal chlorides in the spent liquid phase from the upgrading step are regenerated to produce hydrochloric acid in an acid regeneration zone . In this US patent the upgrading process and the titanium tetrachloride process are integrated. The aim of the process is to obtain titanium tetrachloride, whilst recycling metal chlorides generated during that chlorination process to the acid regeneration zone. The iron oxide products and unconverted metal chloride products from the acid regeneration process are directed to waste. In general, hydrochloric acid has been used in the production of synthetic rutile from ilmenite and other titaniferous materials by a number of leach processes. These processes typically involve the following steps: -

1. Oxidatively roasting the ilmenite.

2. Reducing the product of step 1 at elevated temperature.

3. Cooling the product of step 2. 4. Digesting the cooled product of step 2 in hydrochloric acid.

5. Filtering the product of step 4 to produce filtrate and filter cake.

6. Recovering synthetic rutile from the filter cake.

7. Spray roasting the filtrate to recover hydrochloric acid and generate iron oxide for disposal or sale.

In general, the ilmenite and other titaniferous materials used as starting materials for such processes will have a high content of titania and a low iron content. If low Ti0₂ content/high iron content starting materials are used, either the resulting upgraded product will have a Ti0₂ content of below 85wt%, meaning it is not of high enough quality for conventional uses and titanium tetrachloride manufacture, or the cost of running the upgrading process to reach a high enough Ti0₂ content makes the process inefficient and not cost effective. Summary of the Invention

An embodiment of the invention provides a method for producing titanium oxide from an iron-titanium ore, with co-production of iron oxide, the method comprising:

• providing an iron-titanium ore that comprises from 40 to 65wt% Ti0₂ and from 30 to 55wt% iron species;

• upgrading the iron-titanium ore by treating it with a leach liquor comprising hydrochloric acid, to produce a solid phase of upgraded titania material and a spent liquid phase comprising dissolved metal chlorides, wherein the upgraded titania material contains 75wt% or more Ti0₂;

· separating the solid phase from the spent liquid phase; and

• reacting the metal chlorides dissolved in the spent liquid phase in the presence of oxygen to produce hydrochloric acid and iron oxide, with the reaction being carried out in a fluid bed reactor so as to provide the iron oxide in sintered form.

Optionally, the method may involve converting the upgraded titania material to titanium chloride or titanium metal.

Therefore in one embodiment the method may further comprise the step of: • chlorinating the separated solid phase with chlorine-containing gas in a chlorinator to form titanium chloride, with the chlorination being carried out in a fluid bed reactor in the chlorinator in the presence of carbonaceous material as a reducing agent, to produce a product stream containing a titanium tetrachloride phase and an entrained solids phase, wherein the entrained solids phase contains metal chlorides, unreacted upgraded titanium-containing material and unreacted reducing agent.

In one such embodiment, the titanium tetrachloride is separated from the other products of this step.

Optionally, the method may involve converting the iron oxide to iron and/or steel.

Therefore the method may further comprise the step of:

· reducing the iron oxide to form iron and/or steel.

In one such embodiment, the iron and/or steel is separated from the other products of this step. In one embodiment of the invention, both of the optional converting steps are carried out, such that the method results in the production of titanium tetrachloride as well as iron and/or steel.

A key feature of this invention is that it is designed to make use of a starting material that is an iron-titanium ore that comprises from 40 to 65wt% Ti0₂ and from 30 to 55wt% iron species. Conventional upgrading processes will utilise titaniferous starting materials which have high levels of Ti0₂ and low levels of iron species, in order to ensure that an upgraded material comprising 85wt% or more Ti0₂ can be obtained in a cost effective manner. Therefore the invention is advantageous in that it is able to utilise a starting material that would not normally be used in this field.

The method of the invention upgrades an iron-titanium ore that comprises from 40 to 65wt% Ti0₂ and from 30 to 55wt% iron species, by treating it with a leach liquor comprising hydrochloric acid, to produce a solid phase of upgraded titania material and a spent liquid phase comprising dissolved metal chlorides, wherein the upgraded titania material contains 75wt% or more Ti0₂.

A further key novel aspect of this method is that the metal chlorides dissolved in the spent liquid phase are reacted in a fluid bed reactor, so as to provide the iron oxide in sintered form, especially in the form of sintered pellets. Conventionally, this step for the recovery of hydrochloric acid from the leach liquor is carried out by a spray roasting process, which yields a fine iron ore powder. Such a powder would pass directly to waste, as in US 4 435 365. In contrast, the sintered product of the present invention can be utilised directly in other applications, e.g. in the production of iron and/or steel.

It has therefore been recognised in the present invention that the use of the fluidised bed acid regeneration process is advantageous for this acid regeneration stage, as it means that the iron oxide that is produced in addition to the hydrochloric acid is provided in sintered form and it is therefore in a suitable form to be transferred to an iron ore refining plant, which may be a blast furnace or other process used for the manufacture of iron and/or steel. This goes against all previous teachings where the iron oxide was perceived as a waste material obtained during the recovery of hydrochloric acid.

Further, the present invention uses a starting material that is an iron-titanium ore that comprises from 40 to 65wt% Ti0₂ and from 30 to 55wt% iron species. Whilst this is conventionally viewed as potentially inappropriate for use in the production of titanium oxide products, due to its low titania content, the present invention can make good use of such a starting material. In fact, these relative amounts of titania and iron species mean that the iron oxide co-product is of a relatively high purity, and so is of a quality that allows it to be directly useful, e .g. in the production of iron and/or steel. Thus the present invention has recognised that by selection of the composition of the starting material and selection of a fluidised bed acid regeneration process, useful titanium oxide and iron oxide products can be obtained, and in fact these are obtained from an iron-titanium ore that otherwise would not be seen as a good starting material. Detailed Description of the Invention

The iron-titanium ore used in the present invention is a titanium-source material that includes both titanium and iron. In this regard, it may suitably be any ore that includes titania (Ti0₂) together with at least one iron species, such as one or more ferrous or ferric species (preferably one or more iron oxide such as FeO, Fe₂0₃ and/or Fe₃0₄).

The iron-titanium ore used in an embodiment of the invention comprises from 40 to 65wt% Ti0₂ and from 30 to 55wt% iron species. Thus the iron-titanium ore used in the present invention is an ore with a relatively low titanium content and a relatively high iron content. In contrast, conventional starting materials for the production of synthetic rutile from ilmenite and other titaniferous materials will be high titanium content ores; these will contain less iron. The iron-titanium ore may, for example, be ilmenite. This is well known as the most common titaniferous ore, and it contains titanium and iron oxide as well as small amounts of other metals, e.g. aluminium, manganese and/or magnesium.

In general, any grade of ilmenite may be used as the iron-titanium ore, e.g. any ilmenite with from 40 to 65wt% titanium dioxide may be used. Of course, as the process of the invention requires that the upgraded titanium-containing material (synthetic rutile) is chlorinated, the iron-titanium ore is one that, once upgraded to synthetic rutile, can be subject to chlorination. The process of the present invention does not change the size of the ore and therefore any ore may be used provided that it reacts in the fluid bed chlorinator.

In principle any titaniferous ore that contains both titanium and iron could be used as the starting material, e.g. ilmenite, ilmenite beach sands, natural rutile, perovskite titanomagnetite, leucoxene or anatase ore.

The skilled reader will appreciate that the ore selection dictates the quality of the iron oxide product, as most of the impurities present in the starting ore product will end up in the resulting iron oxide product. Therefore as the choice of the starting material will impact on the purity of the iron oxide produced, the skilled reader will appreciate that the starting material should be selected accordingly, depending on the intended use for the iron oxide co-product and the intended use of the titanium oxide product, e.g. taking into account the suitability of the titanium oxide for fluid bed chlorination to titanium chloride. In the embodiments of the present invention, the iron-titanium ore may contain from 40 to 65wt% titanium dioxide, preferably from 45 to 64wt% or from 45 to 63wt%. The iron-titanium ore to be used will typically have low titanium content, e.g. from 45 to 55% by weight of titanium dioxide. However, it may alternatively have a higher Ti0₂ content, e.g. of from 55 to 64wt%.

In one embodiment, the iron-titanium ore used as starting material has a titanium dioxide content of from 45 to 60wt%, e.g. from 45 to 55wt% or from 47 to 55wt% or from 48 to 55wt%. In one preferred embodiment, the iron-titanium ore used as starting material has a titanium dioxide content of from 50 to 60wt%, e.g. from 50 to 57wt% and in particular from 50 to 55wt%.

Such amounts of titanium dioxide in the starting material may be selected to generate less waste as well as to ensure that the process works at its best. Further, this enables the use of ilmenite ores that are generally not suited for conventional titanium tetrachloride manufacture.

In an embodiment of the present invention, the iron-titanium ore contains from 30 to 55wt% iron species, such as from 33 to 55wt% or from 35 to 55wt%. The iron- titanium ore to be used will typically have a relatively high content of iron species, e.g. from 40 to 50% by weight, especially from 40 to 45wt%. However, it may alternatively have a lower iron content, e.g. of from 35 to 40wt% of iron species. In one embodiment, the iron-titanium ore used as starting material has a content of iron species of from 35 to 52wt%, such as from 35 to 50wt% or from 37 to 50wt%.

In one preferred embodiment, the iron-titanium ore used as starting material has a content of iron species of from 35 to 50wt%, such as from 35 to 47wt% or from 35 to 45%. Such amounts of iron species in the starting material may be selected to generate less waste as well as to ensure that the process works at its best. Further, this enables the production of high quality iron oxide co-product that is suited for direct use in iron and/or steel manufacture.

Preferably some or all of the iron species present in the iron-titanium ore used as starting material are in the form of one or more iron oxide, such as FeO, Fe₂0₃ and/or Fe₃0₄.

In one preferred embodiment, the iron-titanium ore used as starting material has a total content of titania and iron species of 90wt% or more, such as 91wt% or more, or 92wt% or more, or 93wt% or more, or 94wt% or more, or 95wt% or more. It may be from 90 to 99.5wt%, such as from 91 to 99.5wt%, or from 92 to 99wt%, or from 93 to 99wt%, or from 94 to 98.5wt%, or from 95 to 98wt%.

Thus, in general, it is preferred that the amount of metal oxides other than titania and iron oxide is 10wt% or less, preferably 8wt% or less, more preferably 6wt% or less, and most preferably 5wt% or less, e.g. from 0.5 to 5wt% or from 0.5 to 4wt% or from 1 to 3wt%.

The skilled reader will appreciate that the iron-titanium ore used as starting material can have its content analysed and determined using conventional techniques. This may be by use of X-ray fluorescence, but preferably is by chemical methods. Quantitative chemical analysis is well known in the art (see, e.g., "Quantitative Chemical Analysis" Dan Harris, 27 July 2010, W. H. Freeman.)

In this regard, titanium content can suitably be determined by fusing a sample of the iron-titanium ore with potassium hydrogen sulphate in a silica conical flask. The cold melt is extracted in sulphuric acid and the titanium reduced to the trivalent state with zinc amalgam. The reduced titanium is titrated with standard ferric alum using potassium thiocyanate as indicator.

Ferrous ion content can suitably be determined by dissolving a sample of the iron- titanium ore in hydrofluoric and sulphuric acids in a carbon dioxide or nitrogen atmosphere . The solution is added to an excess of boric acid and the ferrous iron titrated with standard eerie sulphate solution.

Total iron content can suitably be determined by fusing a sample of the iron-titanium ore with potassium hydrogen sulphate and dissolving the cooled melt in dilute sulphuric acid solution. The iron is double precipitated as the hydrate and determined by reduction in a silver reductor and titrated with standard eerie sulphate solution.

It is preferred that the provided iron-titanium ore is reduced before the step of upgrading the iron-titanium ore by treating it with a leach liquor comprising hydrochloric acid. In this regard, a reducing step is beneficial in that it will convert any Fe ⁺ in the starting material to Fe²⁺, which will make it more amenable to the leaching process and will therefore improve the extractive efficiency of the leaching. However, this step is not essential as it may be that the levels of Fe ⁺ in the starting material are such that a reduction step is not necessary or not cost effective.

When a reducing step is carried out, this may be implemented by using any suitable reducing agent. Reducing agents are of course well known in the art. One suitable class of reducing agents that may be contemplated for use in the invention are fuel oils (carbonaceous oils) but any other reducing agent that can serve to convert any Fe ⁺ in the starting material to Fe²⁺ can of course be used, for example hydrogen or carbon monoxide.

The reducing step may suitably be carried out at elevated temperature, e.g. at a temperature of 500°C or higher or 600°C or higher, preferably 700°C or higher, e.g. from 700 to 1000°C or higher. The reducing step will normally be carried out at approximately atmospheric pressure, but elevated or reduced pressures could also be used. The reducing step may be carried out for any suitable length of time, e.g. 5 minutes or more, such as 10 minutes or more, preferably 15 minutes or more, e.g. from 15 minutes up to 2 or 3 hours or more. Optionally, prior to the reducing step an oxidative roasting of the iron-titanium ore is carried out. This may be effected under standard oxidative conditions, as is known in the art. However, this step is not essential and may be omitted. The roasting may involve oxidation at an elevated temperature, e.g. at a temperature of 600°C or higher or 700°C or higher, preferably 800°C or higher, e.g. from 800 to 1250°C or higher.

The upgrading step of the invention is preferably carried out at elevated temperature. For example, this may be 70°C or higher, or 80°C or higher; preferably it is 90°C or higher or 95°C or higher.

In one embodiment the upgrading step is carried out at an elevated temperature of 80°C or higher or more preferably 85°C or higher; it may be that the elevated temperature is in the range of from 80°C to 1 10°C, such as from 850°C to 105°C or more preferably from 85°C to 100°C. These temperatures may in particular be selected when the upgrading step is carried out at or near atmospheric pressure .

In one preferred embodiment the upgrading step is carried out at an elevated temperature of 100°C or higher, such as 1 10°C or higher or more preferably 120°C or higher. It may be that the elevated temperature is in the range of from 90°C to 150°C, such as from 100°C to 145°C or from 1 10°C to 140°C. Most preferably the upgrading step is carried out at elevated temperature that is within the range of from 120°C to 140°C. These temperatures may in particular be selected when the upgrading step is carried out at elevated pressure.

The upgrading step may suitably be carried out at either at or near atmospheric pressure or at elevated pressure, e.g. from about 125kPa to 550kPa, such as from about 200kPa to 500kPa; preferably it is from about 225kPa to 450kPa.

The upgrading step may suitably be carried out for about 1 to 10 hours, e.g . from 2 to 8 hours or 3 to 6 hours. The length of the upgrading step will depend on the titanium dioxide concentration in the original ore and the concentration required in the synthetic rutile. In the upgrading step the ore may be subjected to more than one leach cycle, to increase the concentration of titanium dioxide in the upgraded product. Therefore two or more leach cycles may be carried out. It is also possible to carry out a "double leach", in which spent leach liquor is replaced with fresh leach liquor, to achieve a higher leach efficiency.

The leach liquor used in the upgrading step comprises hydrochloric acid. In one embodiment, the leach liquor is an aqueous hydrochloric acid solution. The aqueous hydrochloric acid solution is preferably dilute; for example, it may have a concentration of from 10 to 22% (by volume), e.g. it may be from 15% to 21 % hydrochloric acid or from 16 to 21 %; preferably it is from 18 to 20% (v/v) hydrochloric acid.

The upgrading step results in an upgraded titania material that contains 75wt% or more Ti0₂. Preferably the upgraded titania material contains 80wt% or more Ti0₂, such as from 80 to 95wt% Ti0₂. For example, the upgraded titania material may contain 82wt% or more Ti0₂, or 85wt% or more Ti0₂, such as from 85 to 93wt% Ti0₂. In one preferred embodiment the upgrading step results in an upgraded titania material that contains 80 to 92wt% Ti0₂. In one embodiment the upgrading step results in an upgraded titania material that contains about 90wt% Ti0₂, e .g. from 89 to 91wt%.

The original titaniferous ore is thus upgraded to be a product that has a titanium dioxide content that is useful for transfer to a fluid bed chlorination process, as described later.

The upgraded product is separated from the spent liquid phase. The upgraded product is then suitably dried to remove any water; this may be achieved by any known drying technique, such as by the use of a dryer or calciner or the like. In the process of the invention the spent liquid phase from the upgrading step is reacted in an acid regeneration step to produce hydrochloric acid and iron oxide. The upgraded product, comprising titanium oxide, from the upgrading step may be reacted to produce titanium tetrachloride . The iron oxide, from the acid regeneration step, may be reacted to produce iron and/or steel. The reaction of the metal chlorides dissolved in the spent liquid phase in the presence of air and water to produce hydrochloric acid and iron oxide is described in, e.g. from US 3 825 419, where the iron oxides emerge as a waste product. However, a key aspect of this invention is that this reaction is carried out in a fluid bed reactor so as to provide the iron oxide in sintered form, e.g. in the form of sintered pellets.

In this acid regeneration step, the spent liquid phase from the upgrading step is reacted with oxygen in a fluidised bed reactor. This results in the metal chlorides present in this liquid phase (which will include iron chloride) being converted to metal oxide, with a high proportion of iron.

The iron oxide thus obtained is provided in a useful form, suitable for use in an iron or steelmaking plant. In particular, the acid regeneration step is carried out at elevated temperature, meaning that the iron oxide is obtained in sintered form. In one embodiment the reaction of the spent liquid phase from the upgrading step with oxygen is carried out at from 500 to 1000°C, e.g. from 550 to 900°C. Preferably the reaction is carried out at a temperature of from 700 to 900°C.

The production of the iron oxide in sintered form, e.g. as sintered pellets, makes it a stable and useful product for use in end applications, especially in the manufacture of iron and/or steel, e.g. in a blast furnace . Further, the proportions of components in the starting material (iron-titanium ore) mean that there are relatively low levels of metal oxides that are not iron oxide in the spent liquid phase, which in turn means that the sintered metal oxide product obtained from the acid regeneration step in the fluidised bed reactor has a high proportion of iron oxide . It therefore is of a quality that can be used in end applications, rather than sent to waste; for example it may be used in the manufacture of iron and/or steel, e.g. in a blast furnace.

The reactor consists of a bed of sintered metal oxide particles, which are mainly iron oxides. Such a fluidised bed is well known and is commercially available. The bed is fluidised by an oxygen-containing gas, such as air, which will serve to convert the metal chlorides to the respective metal oxides. The oxygen-containing gas may suitably be produced via a combustion process with a sufficient excess of air or oxygen to carry out the conversion of all the metal chlorides to the respective metal oxides.

The spent liquid phase is fed into the fluidised bed reactor. It is then reacted at elevated temperature. In one embodiment the fluid bed temperature is from 500 to 1000°C, e.g. from 550 to 900°C. Preferably the reaction is carried out at a temperature of from 700 to 900°C.

The metal chlorides in solution react to form hydrochloric acid vapour and metal oxides. The metal oxides will sinter to the particles that comprise the fluid bed. The metal oxides are then removed from the fluidised bed. In particular, the sintered metal oxide product may be removed continually or batch wise from the fluidised bed. In one embodiment, the sintered metal oxide product may be allowed to continuously flow from the fluidised bed, e.g. it may overflow from the bed to an outlet. The spent liquid phase, which provides metal chlorides in solution, is preferably concentrated before it is reacted. This may suitably be achieved by heating. In one embodiment the spent liquid phase is heated using waste heat from the reactor. This is beneficial in terms of avoiding heat going to waste and therefore having a more efficient process.

The acid regeneration step may suitably take place in a hydrochloric acid regeneration plant incorporating a fluidised bed reactor.

The hydrochloric acid vapour can be absorbed into water in a gas absorption system, to obtain hydrochloric acid. This resulting hydrochloric acid may suitably be recycled to the upgrading step, where it can be used as leach liquor.

In relation to the optional step of converting the iron oxide to iron and/or steel, this is based on known techniques. The reduction of iron oxide to iron and/or steel, e.g. in a blast furnace or other reactor, is well known and this stage can be carried out in a conventional manner.

In general, therefore, the apparatus and techniques used in this reduction step are conventional and known to the skilled reader.

In particular, the iron oxide may be reacted at elevated temperature with a carbonaceous reducing agent, to form iron. In general, it is preferred that the carbonaceous material is one that has been subjected to a coking process. These materials include coke, calcined coke which is derived from petroleum or coal, or mixtures of such cokes. However, other carbonaceous reducing agents known in the art could of course be used as alternative materials. In one embodiment the carbonaceous material used as a reducing agent is coke. The elevated temperature in the furnace may suitably be 800°C or higher, especially from 900°C to 2000°C, e.g. from 1000°C to 1800°C.

Impurities such as carbon, sulphur, phosphorus and silicon are removed in a conventional manner. Carbon may be retained to form mild steel or high carbon steel.

Iron may be alloyed with other metals (e.g. chromium, nickel, titanium and/or manganese) to form steel.

The product produced may be any type of iron or steel, e.g. wrought iron, mild steel, high carbon steel, stainless steel, titanium steel, or manganese steel.

The iron or steel may then be used to make an industrial product.

In relation to the optional step of chlorination of the separated solid phase, which contains the upgraded titanium-containing material, this is based on known techniques. As discussed in the background to the invention, the chlorination of titaniferous material in a fluid bed reactor in the presence of coke is well known as a process for forming titanium chloride . In such processes, it is normal practice for particulate coke, particulate titaniferous material, chlorine gas (optionally together with oxygen or air) to be fed into a reaction chamber, and for suitable reaction temperatures and pressures and gas flow rates to be maintained to sustain the fluid bed.

In general, therefore, the apparatus and techniques used in the chlorination step are conventional and known to the skilled reader.

In one embodiment the fluid bed temperature in the chlorinator is controlled to be from 800 to 1500°C, e.g. from 900 to 1300°C, such as from 1000 to 1200°C. The temperature inside a chlorinator can be raised significantly above room temperature, e.g. to about 800 to 1 100°C or higher, by the heat of reaction, by the combustion of coke or other carbonaceous material, and/or by the use of suitable heaters. The adjustment of the temperature of a fluidised bed is of course well within the ability of the skilled reader and is conventional.

The temperature of the chlorinator may be monitored using any suitable equipment or techniques. It may be measured using a standard device for measuring temperature, e.g. a thermocouple or an optical pyrometer. Alternatively, the heat being generated can be determined indirectly, by measurement of the proportions of CO and C0₂ produced.

The pressure used inside the chlorinator may usually be in the region of from about 50 to 200kPa, and preferably from 80 to 150kPa, but could be outside this range if required.

In general, it is preferred that the carbonaceous material is one that has been subjected to a coking process. These materials include coke, calcined coke which is derived from petroleum or coal, or mixtures of such cokes. However, other carbonaceous reducing agents known in the art could of course be used as alternative materials. In one embodiment the carbonaceous material used as a reducing agent is coke .

The chlorine-containing gas used for the chlorination may be 100% chlorine or a gaseous blend comprising chlorine gas may be used, e .g. a blend of chlorine and air or a blend of chlorine and oxygen. The chlorine-containing gas may be chlorine- containing gas that is obtained from another reaction, e .g. as a side-product of another reaction. In one embodiment the chlorine-containing gas is obtained from a reactor where titanium tetrachloride is oxidised. The skilled reader will be aware of the chlorine-based gas blends that can be used in fluid-bed chlorination. Clearly there should be sufficient chlorine in the chlorine-containing gas for the chlorination to readily occur, e.g. there may be 50% v/v or more of chlorine in the chlorine- containing gas, such as 60% or more, 70% or more, 80% or more, 90% or more, 95% or more, or 99% or more v/v.

The chlorinator is suitably a reactor with multiple nozzles or tuyeres for injection of the chlorine gas. The nozzles or tuyeres are suitably located in or near the base . Typically, the point of introduction of the chlorine-containing gas will be located within about 0 to about 3m from the base of the reactor, e.g. about 0 to about 2.4 m from the base of the reactor; preferably from about 0 to about 1.5 m from the base of the reactor. A most typical location is in the base of the reactor. Usually the nozzles or tuyeres are surrounded by in-filling material, e .g. concrete .

The titaniferous material and reducing agent can be maintained as a fluidised bed of solid particles by the chlorine-containing gas passing upwardly through the bed from the nozzles or tuyeres.

The titaniferous material used in the chlorination stage is suitably provided in the form of a particulate solid derived from the described process and may be mixed with other titaniferous materials, and may also include materials that are recycled. . A carbonaceous material, e.g. coke, is also suitably provided in the form of a particulate solid.

The choice and provision of suitable particle sizes, so that the titaniferous material and carbonaceous material is maintained as a fluidised bed of small solid particles by the chlorine-containing gas, is within the skilled reader' s knowledge.

The products from the chlorination reaction, which are removed from the fluidised bed, will be titanium chloride, chlorides of any other metals present in the titaniferous material, unreacted titanium, coke and oxides of any other metals present in the titaniferous material. These products from the chlorination reaction are cooled.

The metal chlorides, other than titanium chloride, will condense to solid form and can therefore be removed, e.g. by a cyclone or other gas-solid separation device.

The unreacted silica and any other species that accumulate within the process can then be removed by conventional mineral separation techniques.

The remaining products discharged from the chlorination reaction can be fed into the upgrading step or into the step of reacting the metal chlorides dissolved in the spent liquid phase.

For example, they may suitably be fed into the leach liquor comprising hydrochloric acid prior to the addition of the unreacted iron-titanium ore. Alternatively, they may be fed directly into the reaction during the upgrading step or may be fed directly into the reaction in the step of reacting the metal chlorides dissolved in the spent liquid phase .

The process thus provides a route for all the iron and other metal species present in the original iron-titanium ore to be converted to metal oxides in a useful form for making of iron or steel, as they will either be dissolved in the spent liquid phase following the upgrading step, and will directly enter the step of oxidising the metal chlorides in a fluidised bed, or will initially be in the upgraded titaniferous product and fed back to reach the step of oxidation in fluidised bed after chlorination and separation from titanium chloride, thus obtaining useful solid metal oxide products.

Titanium dioxide can be recycled within the process until chlorinated.

Coke can also be recycled as a reducing agent in the fluid bed chlorinator, or used as a fuel in a calciner for drying.

Thus, the only waste material will be a small quantity of unreacted silica from the original feedstocks. The invention will now be further described, in a non limiting manner, by reference to the following example.

Example

Ilmenite ore is provided. This may, for example, have the following content:

FeO 19.8wt%

Fe₂0₃ 23.8wt%

Other oxides 4.4wt%

This ore is subjected to a reduction process, at elevated temperature, to convert essentially all of the iron to the FeO state. The reducing agent may be a fuel oil and the reducing step may be carried out at a temperature of from 700 to 1000°C.

The reduced ore is then leached with a leach liquor which is a 20% (v/v) aqueous solution of hydrochloric acid. This results in a solid phase which is synthetic rutile product and a spent liquid phase .

The resulting synthetic rutile product contains:

Ti0₂ 90wt%

FeO 7.3wt%

Other metal oxides 2.7wt%

The metal chlorides dissolved in the spent liquid phase are then reacted in a fluid bed reactor in the presence of air and water to produce hydrochloric acid and sintered iron oxide.

The iron oxide is obtained in the form of sintered pellets and contains :

Fe₂0₃ 90%

Ti0₂ 2.8%

Si0₂ 0.2% A1₂0₃ 0.4%

Sulphur 0.002%

Phosphorous 0.04% The synthetic rutile product is chlorinated in a fluid bed reactor using chorine- containing gas in the presence of coke as a reducing agent, to produce a product stream containing a titanium tetrachloride phase and an entrained solids phase, wherein the entrained solids phase contains metal chlorides, unreacted upgraded titanium-containing material and unreacted coke.

When the by products from this chlorination process are incorporated into the reactant stream for the step of oxidising in a fluid bed reactor, to produce hydrochloric acid and iron oxide, the iron oxide has the following composition: Fe₂0₃ 90%

Ti0₂ 4%

Si0₂ 0.3%

A1₂0₃ 0.8%

Other metal oxides 4.8%

Sulphur 0.002%

Phosphorous 0.04%

The iron oxide sintered pellets can be used in a blast furnace to obtain iron and/or steel.

The starting materials and products from this example may have their contents analysed and determined using quantitative chemical analysis, as discussed in more detail earlier in this application.

Claims

1. A method for producing titanium oxide from an iron-titanium ore, with co- production of iron oxide, the method comprising:

· providing an iron-titanium ore that comprises from 40 to 65wt% Ti0₂ and from

30 to 55wt% iron species;

• separating the solid phase from the spent liquid phase; and

2. The method of claim 1 , wherein the method further comprises converting the upgraded titania material to titanium tetrachloride or titanium metal.

3. The method of claim 2, wherein the method comprises the step of:

• chlorinating the separated solid phase with chlorine-containing gas in a chlorinator to form titanium chloride, with the chlorination being carried out in a fluid bed reactor in the chlorinator in the presence of carbonaceous material as a reducing agent, to produce a product stream containing a titanium tetrachloride phase and an entrained solids phase, wherein the entrained solids phase contains metal chlorides, unreacted upgraded titanium-containing material and unreacted reducing agent.

4. The method of claim 2 or claim 3, wherein the titanium tetrachloride is separated from the other products of the reaction.

5. The method of any one of claims 1 to 4, wherein the method further comprises converting the iron oxide to iron and/or steel.

6. The method of claim 5, wherein the method comprises the step of: • reducing the iron oxide in a blast furnace to form iron and/or steel.

7. The method of claim 5 or claim 6, wherein the iron and/or steel is separated from the other products of the reaction.

8. The method of any one of claims 1 to 8, wherein the iron-titanium ore is ilmenite.

9. The method of any one of claims 1 to 9, wherein the iron-titanium ore comprises from 45 to 60% by weight of titanium dioxide.

10. The method of claim 9, wherein the iron-titanium ore comprises from 50 to 60% by weight of titanium dioxide.

1 1. The method of any one of claims 1 to 9, wherein the iron-titanium ore comprises from 35 to 50% by weight of iron species.

12. The method of claim 1 1 , wherein the iron-titanium ore comprises from 40 to 50% by weight of iron species.

13. The method of any one of claims 1 to 12, wherein the iron-titanium ore comprises iron species in the form of one or more iron oxide, such as FeO, Fe₂0₃ and/or Fe₃0₄.

14. The method of any one of claims 1 to 13, wherein the iron-titanium ore is reduced before the step of upgrading the iron-titanium ore by treating it with a leach liquor comprising hydrochloric acid.

15. The method of any one of claims 1 to 14, wherein the step of reacting the metal chlorides dissolved in the spent liquid phase in the presence of oxygen is carried out at from 500 to 1000°C.

16. The method of any one of claims 1 to 15, wherein the step of reacting the metal chlorides dissolved in the spent liquid phase in the presence of oxygen is carried out in a hydrochloric acid regeneration plant incorporating a fluidised bed reactor.