Method of manufacturing a porous composite feedstock

Abstract

A method of manufacturing a porous composite feedstock as well as a porous composite feedstock for use in the carbochlorination process of making TiCl4 in a fluidized bed reactor is provided. A homogeneous mixture of one or more particulate feedstock materials and a binder are extruded using a stiff vacuum extrusion process to form an extrudate. The extrudate can then be further processed to have a desired water content, particle sizes, and / or other characteristics for use as a porous composite particulate feedstock in the carbochlorination process. The method provides the ability to use a much wider variety and sources of feedstock for use in making TiO2 pigment particles according to the carbochlorination process.

Description

[0001] Method of Manufacturing a Porous Composite Feedstock

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to a method of manufacturing a porous composite feedstock, as well as a composite feedstock manufactured according to the method according to the invention and use of the composite feedstock in the carbochlorination process of making TiCI4 in a fluidized bed reactor during the carbochlorination process.

[0004] BACKGROUND

[0005] Titanium dioxide (“TiO2”) particles are extensively used as pigments in a large variety of materials. Typical TiO2 particles used for most pigment (“TiO2 pigment particles”) typically have an average particle size, that is, the mass-related median d50 (hereinafter, d50), of between 0.05 pm and 1 pm, more typically 0.1 -0.5 pm or even 0.15-0.4 pm, as determined by disc centrifuge, in order to provide the most effective light reflection relative to the wavelengths of light in the visible range. Optionally, the TiO2 pigment particles may have an “almost spherical” form, i.e., that closely approach, but do not necessarily precisely attain, a perfect spherical shape, as opposed to particles that have flake-like or acicular structures.

[0006] In the production of TiO2 particles, typically one of two well-known primary processes is used to reactively transform reduce titanium-containing (“titaniferous”) feedstock, such as Ti- containing slag, into TiO2 particles: the sulphate process or the carbochlorination process. In recent years, the carbochlorination process has gained in usage for various reasons. In the carbochlorination process, titaniferous feedstock is combined with a carbon-containing (“carbonaceous”) feedstock (e.g., coke) and a chlorine source (e.g., CI2) under highly exothermic conditions inside a fluidized bed reactor to form titanium tetrachloride (TiCI4), which can thereafter be processed into TiO2 pigment particles by well-known process steps. In the course of the carbochlorination process, and particularly in the process of the carbochlorination reaction in the fluidized bed reactor, a significant amount of coke and / or titaniferous material is exhausted as unusable and / or uncaptured byproduct in the form of wet petcoke and other exhaust products, which in course of further downstream processing may be contacted with water to produce wet petcoke and other related wet byproducts and aqueous solutions.

[0007] A significant source of cost and environmental carbon footprint in the manufacture of TiO2 pigment particles arises from obtaining suitable carbonaceous and titaniferous feedstocks for the carbochlorination process. Some limiting factors on the types of feedstocks that can be used in the carbochlorination process are the size and moisture content of the feedstock particles, as well as the amount and type of Ti and / or C content of the feedstock. In the past, conventional methods required that feedstocks be pre-processed to fall within relatively narrow range requirements for suitable particle size, moisture, and content, which increases costs and environmental impact of the overall process. Therefore, it would be desirable to be able to use a wider variety of feedstocks of both titaniferous materials and carbonaceous materials.

[0008] One such readily available alternative source of carbonaceous material would be the unused recycled coke materials from the carbochlorination process itself and / or different grades and / or sources of coke and other carbonaceous material. However, conventionally, there have been significant barriers to being able to do this because these recycled materials are typically too small (too fine) and / or have too much moisture for suitable re-introduction into the carbochlorination process. For example, wet petroleum coke (also referred to as “wet petcoke” herein before and after) would be an ideal source of carbonaceous material if it could be transformed into a usable form. Wet petcoke comprises petroleum coke particles with a high moisture content, such as 30 to 40 wt.% moisture, produced by a recycling process, such as, from the unreacted solids fraction exhausted from a carbochlorination reactor in its normal operation mode for generating TiCI4 in the process of making TiO2 pigment particles. However, wet petcoke typically cannot be successfully used in the carbochlorination fluidized bed reactor because it contains excessive moisture (30-40 wt.%) and typically has too many fine particles (80% < 250 pm) to be introduced back to the reactor and successfully participate in the carbochlorination reaction. Similarly, petcoke fines, which typically have 80% or more of the particles with a d50 less than 500 pm, would also be a desirable source of carbonaceous material because these are typically available from the market at lower costs and are usually dry and free flowing. However, these petcoke fines are also usually too fine to be introduced back to the reactor in order to successfully participate in the carbochlorination reaction. In addition, although petcoke fines typically are in the form of a dry powder with a moisture of 5 wt.% or less, petcoke fines can sometimes contain moisture content of up to 20 wt.% even while usually remaining free flowing. Another less expensive source of carbonaceous feedstock is biocoke, which is readily available from the market or from the manifold of theTiO2 manufacturing processes, such as hydrothermal carbonization and / or methane pyrolysis. Use of biocoke could also reduce the carbon footprint of the carbochlorination process by using at least a fraction of renewable resources and hence to move the TiO2 pigment manufacturing industry towards carbon neutrality. However, these biocokes and cokes made from renewable starting materials also typically are too fine and / or too moist for use in the carbochlorination reaction. An alternative source of titaniferous feedstock material would also be desirable. For example, it would be desirable to be able to use slag fines and other types of titaniferous fines readily available from the market as a source of titaniferous feedstock materials feedstocks because they often have titanium contents of 92% or more and are less expensive to obtain. Unfortunately, these slag fines and other titaniferous fines typically have particle size distributions of more than 80% of the particles having a d50 less than 100 pm, which is too fine to be used in the current carbochlorination reactors. In addition, such titaniferous fine materials also often display moisture of up to 5% in order to prevent dusting during transportation, which is too wet to be used in the current carbochlorination reactors.

[0009] Therefore, it would be desirable to have a way to be able to use a wider variety of source materials for the carbonaceous and / or titaniferous materials as feedstock in the carbochlorination process in order be able to reduce the cost of the input materials. In addition, it would also be desirable to have a way to be able to recycle the unused waste materials from the carbochlorination process as source of carbonaceous and / or titaniferous materials that can be used again ad as feedstock in the carbochlorination process in order to reduce waste streams material and the environmental impact of the TiO2 pigment manufacturing process.

[0010] SUMMARY OF THE INVENTION

[0011] The present invention provides a method of manufacturing a porous composite feedstock. The resulting feedstock may be suitable for use in the carbochlorination process that allows for the use of a wider variety of carbonaceous and / or titaniferous feedstock sources, such as coke fines and titaniferous fines of various types, as well as wet petcoke and titaniferous fines and other materials from the TiO2 manufacturing process that could be recycled and re-used as feedstock.

[0012] To achieve one or more of these objectives, a homogeneous mixture of one or more particulate feedstock materials and a binder can be extruded using a stiff vacuum extrusion process to form an extrudate. The extrudate can then be further processed to have a desired water content, particle sizes, poured bulk density, hardness, porosity, and / or other characteristics suitable for use as a porous composite particulate feedstock in a given carbochlorination process. In one aspect of the invention, a method of manufacturing a porous composite feedstock is provided. The method includes mixing a first particulate feedstock material comprising one of a first carbonaceous material and a first titaniferous material, and a binder, to form a homogenous mixture of at least the first particulate feedstock material and the binder. The homogeneous mixture is extruded using a stiff vacuum extrusion process to form an extrudate from the homogeneous mixture. The extrudate is dried to have a water content less than 1.5 wt.%, preferably less than 0.5 wt.%, and more preferably less than 0.1 wt.%. The extrudate is sized, preferably after the drying, to have a particle size distribution between 0.5-6 mm, and preferably between 1-3 mm. The drying may optionally include thermally treating the extrudate and / or other active drying techniques. The dried and sized extrudate may be used in some embodiments directly as the porous composite particulate feedstock, or in other embodiments additional processing steps could be implemented before being used as the porous composite particulate feedstock. Optionally, the resulting porous composite feedstock may be used for the carbochlorination process of making TiCI4 in a fluidized bed reactor, for example, by supplying the porous composite feedstock into a fluidized bed reactor during a carbochlorination reaction. Such TiCI4 may be subsequently processed into TiO2 particles, such as TiO2 pigment particles, by other well understood processes.

[0013] In another preferred embodiment the water content of the porous composite feedstock is less than 4 wt.%, preferably less than 1 wt.%, more preferably less than 0.5 wt.% based on the weight of the composite feedstock.

[0014] In a further preferred embodiment, the water content of the porous composite feedstock is in the range of from 0.01 to 4 wt.%, preferably of from 0.02 to 1 wt.%, more preferably of from 0.03 to 0.5 wt.%, and even more preferably of from 0.04 to 0.4 wt.% based on the weight of the composite feedstock.

[0015] In yet another preferred embodiment the content of volatile compounds comprising hydrogen and oxygen other than water is less than 1 wt.%, and preferably less than 0.5 wt.% based on the weight of the composite feedstock.

[0016] In a further preferred embodiment, the content of volatile compounds comprising hydrogen and oxygen other than water is in the range of from 0.01 to 2 wt.%, preferably is in the range of from 0.02 to 1 wt.%, preferably is in the range of from 0.03 to 0.5 wt.% based on the weight of the composite feedstock.

[0017] In another aspect of the invention, a composite feedstock for use in the carbochlorination process of making TiCI4 is provided. The composite feedstock is manufactured according to any of the methods disclosed herein.

[0018] In another aspect of the invention, use of the composite feedstock in the carbochlorination process of making TiCI4 in a fluidized bed reactor is provided. The composite feedstock is supplied into the fluidized bed reactor during the carbochlorination process.

[0019] In some optional embodiments, the first particulate feedstock material is the first carbonaceous material. The first carbonaceous material is selected from at least one of charcoal, wet petrol coke, wet recycled petrol coke, green (non-calcined) petroleum cokes, green cokes from biorefineries, bituminous coals, green calcined petroleum cokes, calcined cokes from biorefineries, calcined fine petrol cokes, calcined cokes from bio-refineries, gilsonite, anthracite coal, pyrolysis coke, calcined biocoke, calcined HTC (hydrothermal carbon), and biochar. Optionally, the first carbonaceous material is wet petrol coke fines and / or wet recycled petrol coke fines or mixtures thereof having a moisture content of 0-20 wt.%, preferably less than 10 wt.%, and more preferably less than 5 wt.%.

[0020] In other optional embodiments, the first particulate material is the titaniferous material. Optionally, the titaniferous material may include at least one or more of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites, and mixtures thereof. In other optional embodiments, the binder is an aqueous binder.

[0021] In some embodiments, a second particulate feedstock material comprising at least one of a second titaniferous material different than the first titaniferous material and a second carbonaceous material different than the first carbonaceous material is mixed with the first particulate feedstock material and the binder to form the homogeneous mixture. The homogeneous mixture thereby includes at least the first particulate feedstock material, the second particulate feedstock material, and the binder. In some optional embodiments, the second particulate feedstock may include the second carbonaceous material. In some embodiments, the second carbonaceous material comprises at least one of charcoal, wet petrol coke, wet recycled petrol coke, green (non-calcined) petroleum cokes, green cokes from bio-refineries, bituminous coals, green calcined petroleum cokes, calcined cokes from biorefineries, calcined fine petrol cokes, calcined cokes from bio-refineries, gilsonite, anthracite coal, pyrolysis coke, calcined biocoke, calcined HTC (hydrothermal carbon) . In some optional embodiments, the second particulate feedstock comprises the titaniferous material. Optionally, the titaniferous material comprises at least one or more of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites, and mixtures thereof.

[0022] In yet another preferred embodiment the first additive, preferably the first carbonaceous material, has a particle size distribution (PSD) in the range of from 10 pm to 500 pm, preferably of from 25 pm to 400 pm, and more preferably of from 50 pm to 300 pm.

[0023] In some optional embodiments, the first particulate feedstock is a first titaniferous material and the second particulate feedstock comprises a second titaniferous material, wherein the first and second titaniferous materials have different characteristics, such as type, content, source, moisture content, and / or particle size. Optionally, the first and second titaniferous materials are selected from at least one different ones of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites, and / or combinations thereof, preferably selected from at least two different ones of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites, and / or combinations thereof. In other optional embodiments, the first particulate feedstock is a first carbonaceous material and the second particulate feedstock is a second carbonaceous material, wherein the first and second carbonaceous materials have different characteristics, such as type, content, source, moisture content, and / or particle size. Optionally, the first and / or second carbonaceous materials is selected from at least any of the various types of carbonaceous materials disclosed herein. Thus, it is understood that the method of forming the porous composite feedstock , in various embodiments, includes stiff vacuum extrusion of a mixture of one or more types of only carbonaceous material with a binder, preferably an aqueous binder, a mixture of one or more types of only titaniferous materials with a binder, preferably an aqueous binder, and / or a mixture of one or more types of carbonaceous materials and one or more types of titaniferous materials with a binder, preferably an aqueous binder, and any and all various combinations thereof. Optionally, other materials are also present in the mixture that is stiff vacuum extruded, such as other metals, metal oxides, ores, unreacted byproducts or unusable materials from the carbochlorination process, and / or other types of particulate matter by way of example. In yet another preferred embodiment the amount of binder is in the range of from 0.5 to 25 wt.%, preferably of from 1 to 20 wt.%, more preferably of from 2 to 10 wt.%, and more preferably of from 2 to 5 wt.% based on the weight of the porous composite feedstock.

[0024] In another preferred embodiment the porous composite feedstock comprises 2 to 20 wt.%, preferably 3 to 12 wt.%, and more preferably 5 to 10 wt.% of carboxy methyl cellulose based on the weight of the composite feedstock; and / or wherein the porous composite feedstock comprises 2 to 20 wt.%, preferably 3 to 12 wt.%, and more preferably 5 to 10 wt.% of waterglass based on the weight of the composite feedstock.

[0025] According to yet another preferred embodiment the binder comprises more than 20 wt.%, preferably more than 35 wt.%, more preferably more than 50 wt.%, and even more preferably 20 to 75 wt.% of waterglass based on the weight of the binder; and / or the binder comprises more than 20 wt.%, preferably more than 35 wt.%, more preferably more than 50 wt.%, and even more preferably 20 to 75 wt.% of starch or modified starch based on the weight of the binder.

[0026] According to another preferred embodiment the binder comprises 2 to 20 wt.% of modified starch, preferably 3 to 10 wt.% of modified starch, and more preferably 3 to 5 wt.% of modified starch; and / or the binder comprises 2 to 20 wt.% of waterglass, preferably 5 to 10 wt.% of waterglass, and more preferably 5 or 7 wt.% of waterglass; and / or the binder comprises 1 to 20 wt.% of aluminum hydroxide, preferably 1 to 6 wt.% of aluminum hydroxide, and more preferably 1 to 3 wt.% of aluminum hydroxide.

[0027] In some embodiments, one or more of the first particulate feedstock and the second particulate feedstock has an average particle size (d50) less than 50 pm. In other embodiments, the first particulate feedstock and the second particulate feedstock has average particles sizes (d50) between 20 pm to 500 pm, and preferably between 50 pm to 300 pm.

[0028] In some embodiments, at least one, and optionally both, of the first particulate feedstock and the second particulate feedstock has a moisture content more than 1 wt.% during the mixing step. (Moisture acts as a lubricant in the extrusion process.) In some embodiments, the binder comprises an aqueous binder, including any one or more of lignosulfonate, carbohydrates, including glycerin, sugar, molasses, starch, modified starch, cellulose, including carboxymethyl cellulose (CMC), functionalized lignocellulose, lignosulfonate, polyvinyl alcohol (PVA), water-based plasticizers, tannins, and inorganic binders including cement, bentonite, waterglass, aluminum hydroxide, metakaolin, and combinations thereof. In some embodiments, the binder comprises 2- 20 wt.% of modified starch, preferably 3-10 wt.% of modified starch, and more preferably 3 - 5 wt.% of modified starch; the binder may comprise 2-20 wt.% of waterglass, preferably 5-10 wt.% of waterglass, and more preferably 5 - 7 wt.% of water glass; and / or the binder may comprise 1- 20 wt.% of aluminum hydroxide, preferably 1-6 wt.% of aluminum hydroxide, and more preferably 1-3 wt.% of aluminum hydroxide. The wt.% is measured from the contents of the porous composite feedstock after drying.

[0029] In some embodiments, the method further comprises obtaining wet petrol coke and / or wet recycled petrol coke from unreacted solids exhausted from a carbochlorination reactor in its standard operation mode of making TiCI4. The wet petrol coke, wet recycled petrol coke or mixtures thereof are provided as the first particulate feedstock material to be mixed and extruded.

[0030] In some embodiments, the stiff vacuum extrusion process is conducted under vacuum pressures above 5 mbar, preferably between 25-150 mbar, and more preferably between 50- 100 mbar. Preferably, the stiff extrusion is successfully conducted under any pressure below ambient pressure.

[0031] In some embodiments, the stiff vacuum extrusion process is conducted under dynamic pressure of the homogeneous mass acting on a perforated extrusion disc of a vacuum extrusion machine by a transport screw in a second stage of the vacuum extrusion machine ranging from 5 bar to 100 bar, preferably from 20 bar to 40 bar. Optionally, the extrudate exiting through the perforated extrusion disc has a diameter between 4-25 mm, preferably between 17-21 mm, and more preferably 19 mm. The mixing step is optionally performed, for example, with a double shaft mixer.

[0032] In some embodiments, the stiff vacuum extrusion process is conducted under temperatures between 0°C and 80°C, preferably between 30°C and 50°C. In some embodiments, the porous composite particulate feedstock has a hardness, determined by the measurement of the compression strength as specified by ASTM D4179- 01(2006), of at least 0.8 N / mm2or more, preferably more than 2.0 N / mm2.

[0033] In some embodiments, thermally treating the extrudate includes pyrolyzing the extrudate. Such pyrolyzing may include calcinating the extrudate to have a lower porosity than before the calcinating. For example, the thermal treatment is conducted at temperatures substantially above 300°C so as to induce pyrolysis of the extrudate. Optionally, the thermal treatment is conducted at temperatures above 700°C or higher, for example between 600°C-1300°C, preferably between 700°C and 1100°C, and more preferably between 750°C and 950°C, and under exclusion of oxygen to cause calcination of the extrudate. However, in other embodiments, the thermal treatment is conducted at temperatures below 300° C and / or with moving air in order to prevent pyrolyzation and / or calcination. Thermal treatment may also be performed at lower temperatures, e.g. from 80°C to 160°C, when appropriate amount of moving air for convection is provided and sufficient duration of the treatment is ensured.

[0034] In some embodiments, the step of sizing the extrudate includes one or more operation cycles of crushing and / or sieving the extrudate.

[0035] In some embodiments, after the thermal treatment and sizing, the extrudate forms a porous composite particulate feedstock having a bulk density between 0.3-1.6 g / cm3, and preferably between 0.4-0.9 g / cm3. The extrudate after sizing optionally has a sphericity of 0.7 or greater.

[0036] In some embodiments, the method results in the formation of a porous composite particulate feedstock that is mechanically stable under the conditions in the fluidized bed reactor, for example, under static pressures between 0.5 bar gauge and 2 bar gauge, preferably between 0.8 bar gauge and 1.2 bar gauge and, for example, under temperatures between 600°C and 1100°C, preferably between 750°C and 950°C. Preferably, the porous composite particulate feedstock can function in the carbochlorination reaction according to the shrinking core model, in which the porous composite particulate feedstock particles react preferably on the surface of the particles and do not disintegrate to smaller particles due to the mechanical and chemical strain in the reactor. In a preferred embodiment the porous composite feedstock has a particle size distribution (PSD) in the range of from 0.1 mm to 10 mm, preferably of from 0.2 mm to 6 mm, more preferably of form 0.3 mm to 5 mm, and even more preferably of from 0.4 to 3 mm.

[0037] According to a preferred embodiment the metal oxide containing material, preferably the titaniferous material, has a particle size distribution (PSD) in the range of from 10 pm to 500 pm, preferably of from 25 pm to 400 pm, and more preferably of from 50 pm to 300 pm.

[0038] According to a yet another preferred embodiment the second additive has a particle size distribution (PSD) in the range of from 10 pm to 500 pm, preferably of from 25 pm to 400 pm, and more preferably of from 50 pm to 300 pm.

[0039] According to a preferred embodiment the porous composite feedstock has a hardness, determined by the measurement of the compression strength as specified by ASTM D4179-01 (2006), of at least 0.8 N / mm2, preferably at least 0.9 N / mm2, more preferably at least 1.4 N / mm2, and even more preferably of at least 2.0 N / mm2; and / or a porosity, as measured by mercury intrusion and extrusion measurement method, of 10 to 90%, preferably of 20 to 80% and more preferably of 30 to 70%; and / or a porosity, as measured by the low-temperature nitrogen adsorption measurement method according to Barrett, Joyner, and Halenda, of 10 to 90%, preferably of 20 to 80% and more preferably of 30 to 70%; and / or a BET value of more than 10 m2 / g, preferably more than 100 m2 / g, and even more preferably more than 200 m2 / g, and preferably not exceeding 2000 m2 / g.

[0040] The hardness, determined by the measurement of the compression strength as specified by ASTM D4179-01 (2006), is preferably in the range of from 0.8 to 10 N / mm2.

[0041] In some configurations, the method of manufacturing a porous composite feedstock of the present invention provides the ability to use a much wider variety and sources of feedstock for use in making TiO2 pigment particles according to the carbochlorination process, which may reduce material costs, allow for recycling and reuse of otherwise unusable waste and / or byproduct materials from the carbochlorination process and / or other processes, and / or reduce the environmental impact of the TiO2 manufacturing process. Other advantages, uses, and / or characteristics will become apparent upon review of the following detailed description and the drawings.

[0042] BRIEF DESCRIPTION OF THE DRAWINGS

[0043] FIG. 1 is a schematic representation of an example embodiment of a method and processing line for manufacturing a porous composite feedstock for use in the carbochlorination process according to some aspects of the invention; and

[0044] FIG. 2 is an end view of a perforated extrusion disc for a vacuum extruder.

[0045] DETAILED DESCRIPTION

[0046] The following description is meant to describe what is shown in the drawings and / or various contemplated embodiments shown and / or related to what is shown in the drawings. The embodiment(s) shown in the drawings are non-limiting examples and do not themselves define the invention. Any of the features shown and / or described in relation to one embodiment may be combined with any one or more features shown and / or described relative to another embodiment. Any dimensions shown in the drawings and / or described hereinafter are exemplary only and are not intended to limit the scope of the invention. The terms “a” and “an” as used herein to introduce a feature are used as open-ended, inclusive terms to refer to at least one, or one or more of the features, and are not limited to only one such feature unless otherwise expressly indicated. Similarly, use of the term “the” in reference to a feature previously introduced using the term “a” or “an” does not thereafter limit the feature to only a single instance of such feature unless otherwise expressly indicated.

[0047] FIG. 1 schematically illustrates an example of a system 10, such as an industrial chemical manufacturing line, for implementing a method according to certain aspects of the invention. One or more storage structures, such as silos 12, contain one or more particulate feedstocks, respectively. For example, there may be a single silo 12 containing only a single particulate feedstock, or there may multiple silos 12 containing any one or more of the particulate feedstocks discussed herein that can be used to make the composite feedstocks, or a single silo could contain multiple types of particulate feedstocks. The particulate feedstock(s) can be carbonaceous materials, such as wet petcoke and / or petcoke fines, and / or titaniferous material, such as a titanium carrying ore or a TiO2 carrying material. Other types of carbonaceous materials that could be used include HTC coke and / or pyrolysis coke. A second storage structure, such as a second silo 14, contains any one or more of the binders, preferably of the aqueous binders, discussed herein or otherwise suitable for binding the particulate feedstocks in a stiff vacuum extrusion process. As used herein, the term aqueous binders refers to binders that contain the major fraction of hydrogen (H) in form of free water (H2O), or in case of starches, sugars, molasses, etc., in the form of -C-O-H groups, i.e. alcohol groups. This does not generally exclude the presence of water. This is in contrast to nonaqueous binders, which contain hydrogen (H) directly bound to carbon (C-H bond). A variety of different aqueous binders could be used in the process, either separately or in combination, such any one or more of lignosulfonate, carbohydrates, including glycerin, sugars, molasses, starch, modified starch, cellulose, including carboxymethyl cellulose (CMC), functionalized lignocellulose, lignosulfonate, polyvinyl alcohol (PVA), water-based plasticizers, tannins, and inorganic binders including cement, bentonite, waterglass, aluminum hydroxide, metakaolin, and combinations thereof. In some embodiments, the aqueous binder is composed primarily of waterglass, modified starch dry powder, aluminum hydroxide powder, or mixtures thereof. In some nonlimiting embodiments, for example, the binder has a composition of 2- 20 wt.% of modified starch, preferably 3-10 wt.% of modified starch, and more preferably 3-5 wt.% of modified starch; 2-20 wt.% of waterglass, preferably 5-10 wt.% of waterglass, and more preferably 5- 7 wt.% of waterglass; and 1-20 wt.% of aluminum hydroxide, preferably 1-6 wt.% of aluminum hydroxide, and more preferably 1- 3 wt.% of aluminum hydroxide. However, other binder compositions could be used.

[0048] In a first step, the particulate feedstock(s) are mixed with the binder(s), preferably the aqueous binder(s), to form a substantially homogeneous mixture of the particular feedstock material and the binder. In the example arrangement of FIG. 1 , powdered ingredients are transported to a mixer 18, such as a double shaft mixer or any other mixer suitable for mixing particulate and liquid materials together. The powdered ingredients may be transported by any suitable mechanism. In this example, the powdered ingredients are transported from the silo(s) 12 with one or more screw conveyers 16, which may help mix the powdered ingredients. Liquid ingredients, such as the binder, preferably the aqueous binder, are dosed to the first section of the double shaft mixer 18, and the mixer 18 then mixes the particulate feedstock(s) and the binder(s), preferably the aqueous binder(s), such that the materials are homogenized before they enter the extruder 20. Full homogenization of the particulate feedstock with the binder is preferred for wetting all of the particles with the binder.

[0049] Many different combinations of particulate feedstock materials and binder materials can be used for the homogeneous mixture. The particulate feedstock used for the process may be only a single type of feedstock material, or the particulate feedstock may be a combination of two or more types of feedstock materials. For example, the particulate feedstock provided for extrusion may be only one single type of feedstock, such as only wet petcoke or only petcoke fines or only titaniferous material, etc. Alternatively, the particulate feedstock provided for extrusion may include two or more different types of carbonaceous materials, two or more different types of titaniferous materials, or both carbonaceous materials and titaniferous materials. Some non-limiting examples of carbonaceous particulate feedstock materials suitable for use include any one or more of charcoal, wet petrol coke, wet recycled petrol coke, green (non-calcined) calcined fine petroleum cokes, green calcined cokes from bio-refineries, bituminous coals, calcined petrol coke, calcined petroleum cokes, calcined cokes from biorefineries, gilsonite, anthracite coal, pyrolysis coke, biocoke, HTC (hydrothermal carbon), biochar, wet petrol coke fines, wet recycled petrol coke fines and / or petrol coke fines. However, other types of carbonaceous materials could be used. Any of these carbonaceous particulate feedstock materials may have a moisture content of more than 1 % and up to at least 20 wt.% (sometimes more), although lower moisture contents are more desirable. For example, petcoke fines typically have less than 10% or even less than 5% moisture contents. As an example, wet (recycled) petrol coke can be obtained from unreacted solids exhausted from a carbochlorination reactor in the same plant in its standard operation mode of making TiCI-4. The wet (recycled) petrol coke may then be provided as at least one particulate feedstock material to be mixed and extruded. Titaniferous particulate feedstock materials suitable for use may include any one or more of one or more of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites, and mixtures thereof; however, it is foreseeable that other titaniferous particulate materials could be used, and this list is not considered to be exhaustive. For example, the titaniferous material could include titanium-bearing byproduct from the carbochlorination reactor that are too big or too small or otherwise unsuitable for TiO2 pigment particles. Advantageously, any one or more of the particulate feedstocks may have much smaller average particle sizes (d50) than would typically be used for the carbochlorination process, even down to less than 50 pm. In some nonlimiting embodiments, the particulate feedstock(s) may have average particles sizes (d50) between 20 pm to 500 pm, and even between 50 pm to 300 pm. The ability to use particulate feedstocks this fine can allow the use of many more feedstocks than previously usable in the carbochlorination process and thereby significantly change the market and production processes for TiO2 pigment particles. Similarly, any one or more of the binder materials, preferably the aqueous binder materials, mentioned herein may be used. Although the feedstock materials and the binder materials may be stored and / or transported to the mixer in almost any arrangement, it is preferred that the powder materials are stored separately from the liquid materials. Further, each different type of feedstock material and binder material is preferably stored separately from other types (e.g., each type of material is stored in a different silo 12 or 14) for ease of distribution and metering; although this is not always necessary either. Next, the homogenized mixture is extruded using a stiff vacuum extrusion process to form an extrudate from the homogeneous mixture. The stiff vacuum extrusion is preferably conducted in a manner that provides an extrudate having a hardness, a porosity and / or density that, after later drying and sizing, will provide a suitable feedstock for the carbochlorination reaction as run in the fluidized bed reactor. To accomplish this, the vacuum extruder is run at a vacuum pressure and dynamic pressure selected to provide the needed hardness, porosity and density of extrudate. In this example configuration, the homogenized mixture is transferred from the double shaft mixer 18 to a vacuum extruder 20 by any convenient mechanism, for example by feeding directly from the mixer 18 into the extruder 20 or with any suitable conveyor mechanism. The vacuum extruder 20 is an extruder that extrudes the extrudate material under vacuum pressure, thereby implementing a stiff vacuum extrusion process on the homogenous mixture coming from the mixer 18. The stiff vacuum extrusion process may be conducted under vacuum pressures above 5 mbar, preferably between 25-150 mbar, and more preferably between 50-100 mbar. In one nonlimiting arrangement, the vacuum extruder 20 is a two-stage vacuum extruder operated at relatively constant vacuum pressure between 50 mbar and 100 mbar in the second stage, although higher or lower vacuum pressures may be used. To obtain the desired hardness, density and porosity of the ultimate composite feedstock, the dynamic pressure in the second stage of the vacuum extruder 20 formed by the transport screw of the solids on the perforated disc(s) 30 at the extruder head can be controlled. The dynamic pressure from the transport screw preferably ranges between 5 bar to 100 bar, preferably from 10 bar or 20 bar to 40 bar. The density and porosity of the extrudate can also be controlled by the size and / or total area of the perforations 32 through the extruder disc 30. The extrudate diameter through the perforations 32 from the perforated disc(s) 30 preferably ranges between 4 mm and 30 mm. In some arrangements, the perforations 32 have diameters between 15 mm and 25 mm, preferably between 17-21 mm. In some arrangements, the perforations 32 have a diameter of 19 mm. Of course, the size of the extrudate forced through the perforations by the vacuum extruder 20 will correspond to the size of the perforations 32. The size of the perforations 32 and extrudate can be chosen to compromise between throughput of extrudate and the hardness and / or stability of the agglomerates in the extrudate. The stiff vacuum extrusion process may be conducted under temperatures between 0°C and 80°C, preferably between 30°C and 50°C, in order to provide for suitable extrudability.

[0050] Next, the raw extrudate from the extruder 20 is preferably dried and / or heat treated to a preselected, desired moisture content. Typically, the extrudate may have has a moisture content from 25% to 35% when it first exits the vacuum extruder 20 through the extrusion disc 30. Preferably, this moisture is removed prior to the use of the agglomerates in the carbochlorination reactor, for example, because hydrogen atoms in the moisture (water) can form HCI in the carbochlorination reactor, which is typically not desirable because it can lead to undesirable hardness / stability of agglomerates, corrosion, and / or loss of chlorine values. Therefore, the extrudate from the vacuum extruder 20 can be dried to an acceptable moisture level that prevents or minimizes detrimental effects in the carbochlorination process. The extrudate may be actively dried by thermally treating (heat treating) the extrudate in a dryer 22 to reduce the water content of the extrudate to a desired acceptable level in order to speed up the drying process. In this example, the dryer 22 is a typical belt dryer that heats the extrudate to a temperature lower than what would cause pyrolysis of the extrudate, although other types of dryers could be used. In some embodiments, the drying is typically accomplished temperatures at low enough so as to not induce pyrolysis, which typically occurs at temperatures substantially above 300°C. Typically, the drying occurs at temperatures well below 300°C, such as less than 150°C or preferably less than 100°C. Optionally, the active drying may include using air, such as blowing air across the extrudate, to assist with the drying. However, in other embodiments, the thermal treatment may also include pyrolyzing the extrudate in addition to drying. Such pyrolyzing may include calcinating the extrudate to have a lower porosity and higher hardness than before the calcinating. For example, the thermal treatment may be conducted at temperatures substantially above 300°C so as to induce pyrolysis of the extrudate. Optionally, the thermal treatment may be conducted at temperatures above 700°C or higher, for example between 600°C-1300°C, preferably between 700°C and 1100°C, and more preferably between 750°C and 950°C, and under exclusion of oxygen to cause calcination of the extrudate. Of course, in other embodiments, the drying step could be accomplished by other mechanisms, such as solely with blown air, or purely passively. In any case, for best results when later used in the carbochlorination process, the moisture in the extrudate is preferably removed during the drying step such that the extrudate to has a water content less than 1 .5 wt.%, preferably less than 0.5 wt.%, and more preferably less than 0.1 wt.% to form dry extrudate.

[0051] In order for the dry extrudate to be used in the carbochlorination reactor according to the desired fluidization regime, the extrudate typically needs to be sized to have a particle size distribution (PSD) appropriate for the carbochlorination process. The particle size distribution (PSD) is usually determined by sieve analysis, where a sample of the aggregate is sieved through a series of progressively finer sieves to separate the particles by size. The mass or percentage of the sample that passes through each sieve is then measured and used to calculate the PSD. Alternatively or supplementary to the sieve analysis, PSD can be determined by using laser scattering methods using e.g. Mastersizer device by Malvern Panalytical Ltd. Typically, the extrudate is sized to have a particle size distribution between 0,1 to 10 mm (100 pm to 10000 pm), and preferably between 0,2 to 6 mm (200 to 600 pm), more preferably between 0,3 to 5 mm (300 to 5000 pm), and even more preferably 0,4 to 3 mm (400 to 3000 pm) for best results when it is to be used as a feedstock in the carbochlorination process of making TiCI4 in a fluidized bed reactor, although other sizes may be used in some processes. The sizing can be accomplished by any convenient method. Typically, sizing the extrudate is accomplished after the extrudate has been dried, although in some configurations, the extrudate could be sized prior to the drying. In this example, the sizing is accomplished with a crusher 24 and a sieve 26 after the drying step in the dryer 22.

[0052] Regardless of the exact mechanisms and order used to dry and size the extrudate, the drying and sizing is preferably conducted such that the extrudate forms porous composite particulate feedstock having a poured bulk density between 0.3-1 .6 g / cm3, and preferably between 0.4- 0.9 g / cm3. The porous composite particulate feedstock can then be packaged, further processed, transported and / or used as titaniferous feedstock in a fluidized bed carbochlorination reactor 28 as part of a carbochlorination process for making TiO2 pigment particles. Advantageously, porous composite particulate feedstock formed in this manner can have a hardness of at least 0.8 N / mm2, and preferably a hardness of more than 2.0 N / mm2, which helps provide additional mechanical stability of the porous composite particulate feedstock during transport, storage, and introduction into the carbochlorination reactor to prevent the particles from breaking down into particles sizes that are again too small for effective use in the carbochlorination reaction.

[0053] Following are specific test examples of porous composite feedstocks manufactured in accordance with certain principles of the present invention.

[0054] Measurement methods

[0055] The hardness is determined by the measurement of the compression strength as specified by ASTM D4179-01 (2006).

[0056] The porosity is measured by the mercury method, which is also referred to as Mercury Intrusion Porosimetry.

[0057] The poured density or apparent density of the materials used in the examples as stated below was measured according to ISO 697 - 1981 “Surface active agents - washing powders - Determination of apparent density - Method by measuring the mass of a given volume. The receiver used for carrying out the measurements was an apparatus for determination of bulk density SMG 697, commercially available from company powtec Maschinen und Engineering GmbH in Remscheid, Germany, having a receiver capacity of 500 ml. For the measurements, the sieve fraction between 500 and 2000 pm has been used.

[0058] Poured bulk density measurement

[0059] The poured bulk density is determined by the ratio of the mass to a given volume. For the determination, the substance is put into a receiver of known dimensions and weight. The apparatus used for determination of the porous bulk density is SMG 697 provided by Powtec Maschinen und Engineering GmbH (Remscheid, Germany).

[0060] The International Standard ISO 697 describes the procedure of the determination of density and the tools required. The International Standard ISO 697 distinguishes two types for the determination of apparent bulk density. They basically differ in the size of the receivers used. Type SMG 697 fulfils the conditions indicated in ISO 697 and is delivered with a 500 ml receiver. The instruments for the determination of density imply a lockable funnel of fixed dimensions, a receiver and a stand that holds them together in a defined position. The funnel is then filled with the sample of powder or granule then opened. The sample then flows into the receiver with the known volume and the density is obtained by weighing the receiver. In case of powders containing lumps, the method is applicable only if these can be disintegrated readily without breaking down the particles of the powder. The sieve fraction between 500 pm and 2000 pm was used for measuring the density of the material (after comminution).

[0061] BET determination

[0062] Determination of the volume-specific surface area of solids by low-temperature nitrogen adsorption measurement method according to Brunauer, Emmet and Teller as specified by ISO 9277

[0063] The device TriStar II - Micromeritics works according to the classic, static volumetric principle. After the basic preparation of the sample, a corresponding sample quantity displaying an equivalent of approx. 10m2 / g BET surface is placed into the measuring cell and brought to a target measurement temperature of 77 Kelvin. A defined quantity of gas from a known gas volume container is introduced into the sample chamber and the prevailing equilibrium pressure is measured. The amount of the adsorbed gas is calculated from the volumes and pressures measured before and after adsorption. The surface area coverage and the equilibrium pressure are increased by gradually adding the gas amount, whereas 3 to 7, preferably 5 measurement points are taken into account for the evaluation. The value for the volume-specific surface area is determined by mathematical processing of the data. The measurements are validated against Silica-Alumina standard sample with known BET.

[0064] Determination of the material hardness by the measurement of the compression strength as specified by ASTM D4179-01 (2006)

[0065] The device DARTO PM 10 works according to the mechanical principle, where the force at the breakage point is measured on the pellet sample, when a pellet sample is placed between two metal plates, which are compressed at a fixed strain rate while force and distance are recorded in form of compression curves. The pellet hardness is expressed in [N / mm2] as the maximum compression strength required to crush the pellet of given length. The procedure is replicated from 3 to 10 times, preferably 5 times, and the average of all measurements taken is determined.

[0066] Determination of the pore volume and pore size distribution of solids by low-temperature nitrogen adsorption measurement method according to Barrett, Joyner, and Halenda as specified by DIN 66134.

[0067] The device TriStar II - Micromeritics works according to the classic, static volumetric principle. After the basic preparation of the sample, a corresponding sample quantity displaying an equivalent of approx. 10m2 / g BET surface is placed into the measuring cell and brought to a target measurement temperature of 77 Kelvin. A defined quantity of gas from a known gas volume container is introduced into the sample chamber and the prevailing equilibrium pressure is measured. The amount of the adsorbed gas is calculated from the volumes and pressures measured before and after adsorption as well as before and after desorption. Complete adsorption and desorption isotherms are determined according to this procedure, whereas 40 to 60, preferably 50, measurement points are taken into account for each isotherm. The pore volume and the pore size distribution are obtained by mathematical processing of the data, using Kelvin equation. The measurements are validated against Silica- Alumina standard sample with known pore diameter, pore volume and pore size distribution.

[0068] Determination of the pore diameter, pore volume and pore size distribution by Hg-intrusion and extrusion measurement as specified by ISO 15901-1 and DIN 66133 The devices Belpore HP - Microtrac or Quantachrome PoreMaster 60 - Anton Paar work according to the physical principle where a non-reactive, non-wetting fluids like mercury penetrates fine pores at sufficient pressures applied to allow the intrusion of the sample. After the preparation of the sample, it is introduced into the sample cell called a penetrometer. The cell is evacuated, and backfilled with Mercury. For the measurements of larger pores gas pressure of up to 3,45 bar is applied upon the sample pneumatically. For measurements of smaller pores, liquid pressure of up to 4140 bar is applied upon the sample hydraulically. After the quantification of the Mercury amount intruded into pores in each pressurization event (pneumatic and hydraulic), the pressure is then decreased to ambient atmospheric pressure. The depressurization event results in retraction of the mercury, i.e. extrusion from the pores. The pore diameter, pore volume and the pore size distribution are obtained by mathematical processing of the pressure dependent intrusion and extrusion volume data, using the Washburn equation.

[0069] Example 1 :

[0070] 2000 kg / h of wet recycled petrol coke having a moisture content of 38 wt.% were premixed with 700 kg / h of dried fine petrol coke having a moisture content of less than 0.5 wt.%, which resulted in a mixture of wet recycled petrol coke and dried petrol coke having moisture of 28 wt.%. To this mixture, modified starch dry powder was added at a rate of 140 kg / h and mixed to form a homogeneous mixture of the wet recycled petrol coke, dried petrol coke, and modified starch powder. The homogeneous mixture was transferred to and extruded through the vacuum extrusion machine (J.C Steele & Sons HD-10 extrusion system) operated at a dynamic pressure of 7 bar, a vacuum of 40 mbar, and a screw speed of 20 rpm resulting in torque of 83 Nm using a perforated disc with individual hole openings with diameters of 19 mm. The extrudate was then dried at 80°C in a belt dryer to achieve a moisture content below 0.5 wt.%. The dried extrudate was then sized by crushing and sieving to obtain agglomerated particles of the porous composite particulate feedstock having sizes between 1 mm to 3 mm. The oversize and undersize (less than 1 mm and greater than 3 mm) agglomerated particles were returned to the beginning of the process as 700 kg / h stream for reusing in another round of forming porous composite feedstocks. The final agglomerated and dry porous composite particulate feedstock contained 7.3 wt.% of starch, as measured relative to the contents of the porous composite feedstock after the drying. Example 2:

[0071] 1850 kg / h of wet recycled petrol coke having a moisture content of 38 wt.% were premixed with 650 kg / h of dried fine petrol coke having a moisture content of less than 0.5 wt.%, which resulted in a mixture of wet recycled petrol coke and dried petrol coke having moisture of 28 wt.%. To this mixture, dry modified starch powder was added at a rate of 130 kg / h, and 220 kg / h of water glass was added as an aqueous formulation with 44.5% of active ingredient, and the entire mixture was mixed to form a homogeneous mixture of the wet recycled petrol coke, dried petrol coke, modified starch powder, and water glass. The homogeneous mixture was transferred to and extruded through the vacuum extrusion machine operated at a dynamic pressure of 19 bar, a vacuum of 30 mbar, and a screw speed of 20 rpm resulting in torque of 150 Nm using a perforated disc with individual hole openings having diameters of 19 mm. Extrudate was then dried at 80°C in a belt dryer to achieve a moisture content below 0.5 wt.%. The dried extrudate was then sized by crushing and sieving to obtain agglomerated particles of the porous composite particulate feedstock having sizes between 1 mm to 3 mm. The oversize and undersize (less than 1 mm and greater than 3 mm) agglomerate particles were returned to the beginning of the process as 650 kg / h stream for reusing in another round of forming porous composite feedstocks. The final agglomerated and dry porous composite particulate feedstock contained 7.3 wt.% of starch and 12 wt.% of waterglass, as measured relative to the contents of the porous composite feedstock after the drying.

[0072] Example 3:

[0073] 1800 kg / h of wet recycled petrol coke having a moisture content of 38 wt.% was premixed with 600 kg / h of dried fine petrol coke having a moisture content of below 0.5 wt.%, which resulted in a mixture having moisture of 28 wt.%. To this mixture, dry modified starch powder was added at a rate of 125 kg / h, 210 kg / h of water glass was added as an aqueous formulation with 44.5% of active ingredient, and 80 kg / h of aluminum hydroxide powder was added, and the entire mixture was mixed to form a homogeneous mixture of the wet recycled petrol coke, dried petrol coke, modified starch powder, water glass, and aluminum hydroxide powder. The homogeneous mixture was transferred to and extruded through the vacuum extrusion machine operated at a dynamic pressure of 29 bar, a vacuum of 25 mbar, and a screw speed of 8 rpm resulting in torque of 250 Nm using a perforated disc with individual hole openings having diameters of 19 mm. The extrudate was then dried at 80°C in a belt dryer to achieve a moisture content below 0.5 wt.%. The dried extrudate was then sized by crushing and sieving to obtain agglomerated particles of the porous composite particulate feedstock having sizes between 1 mm to 3 mm. The oversize and undersize (less than 1 mm and greater than 3 mm) agglomerated particles were returned to the beginning of the process as 650 kg / h stream for reusing in another round of forming porous composite feedstocks. The final agglomerated and dry porous composite particulate feedstock contained 7.3 wt.% of starch, 12 wt.% of water glass, and 5 wt.% of aluminum hydroxide, as measured relative to the contents of the porous composite feedstock after the drying.

[0074] Following the general process described above, other formulations of porous composite particulate feedstocks with the following materials and properties listed in Table 1 below were obtained. Table 1 : Porous composite feedstock formulations Example 4:

[0075] 1000 kg of wet petcoke having a moisture content of between 30-40 wt.% is pre-mixed with 50 kg modified starch powder. To this pre-mixture, 70 kg of liquid waterglass is added as an aqueous formulation, and the entire mixture is mixed in a double shaft mixer to form a homogeneous mixture of the wet recycled petcoke, modified starch powder, and water glass such that substantially all of the petcoke particles are wetted with the binder (waterglass and modified starch powder). Next, the homogeneous mixture is transferred to and extruded through the vacuum extrusion machine operated at a dynamic pressure from the extrusion screw of 10-40 bar and a vacuum of 50-100 mbar, using a perforated disc with individual hole openings having diameters of 19 mm. To reduce the moisture content of the extrudate to a more desirable level for use in the carbochlorination process, the extrudate is then dried in a belt dryer to achieve a moisture content below 1.0 wt.% relative to the total mass of the dried extrudate. The dried extrudate is then sized to a more suitable size for use in the carbochlorination process by crushing and sieving the dried extrudate to obtain agglomerated particles of the porous composite particulate feedstock having sizes between about 500 pm- 5000 pm (0.5-5 mm) and a density of the particles ranging between 0.8 g / cm3 and 1.2 g / cm3.

[0076] A porous composite particulate feedstock manufactured according to the principles presented herein, in some embodiments, is suitable for use in the carbochlorination process of making TiCI4. In use, the porous composite particulate feedstock may be supplied into the fluidized bed reactor during the carbochlorination process of making TiCI4 in a fluidized bed reactor in any suitable manner, such as through one or more pipes or other inlets into the fluidized bed reactor before and / or during the carbochlorination reaction process.

[0077] From these examples, it can be seen that the method of manufacturing a porous composite feedstock of the present invention may provide the ability to use a much wider variety and sources of feedstock for use in making TiO2 pigment particles according to the carbochlorination process than previously available with conventional methods.

Claims

CLAIMS1. A method of manufacturing a porous composite feedstock, the method comprising: mixing (a) a first particulate feedstock material comprising one of a first carbonaceous material and a first titaniferous material, and (b) a binder, to form a homogenous mixture of the first particulate feedstock material and the binder; extruding the homogeneous mixture using a stiff vacuum extrusion process to form an extrudate from the homogeneous mixture; drying the extrudate to have a water content of less than 1.5 wt.%, preferably less than 0.5 wt.%, and more preferably less than 0.1 wt.%; and sizing the extrudate, preferably after the drying, to have a particle size distribution between 0.5-6 mm, preferably between 1-3 mm.

2. The method of claim 1 , wherein the step of mixing further comprises: mixing (c) a second particulate feedstock material comprising at least one of a second titaniferous material different than the first titaniferous material and a second carbonaceous material different than the first carbonaceous material with the first particulate feedstock material and the binder to form the homogeneous mixture comprising the first particulate feedstock material, the second particulate feedstock material, and the binder.

3. The method of any one of the previous claims, wherein the first particulate feedstock material is the first carbonaceous material selected from at least one of charcoal, wet petrol coke, wet recycled petrol coke, green (non-calcined) calcined fine petroleum cokes, green calcined cokes from bio-refineries, bituminous coals, calcined fine petrol cokes, calcined cokes from bio-refineries, gilsonite, anthracite coal, pyrolysis coke, biocoke, HTC (hydrothermal carbon), biochar or mixtures thereof, and preferably wherein the first carbonaceous material is wet petrol coke, or wet recycled petrol coke fines or mixtures thereof, and more preferably wherein the first carbonaceous material is petrol coke fines, recycled petrol coke fines or mixtures thereof having a moisture content of 0-20 wt.%, preferably less than 10 wt.%, and more preferably less than 5 wt.%; and / or wherein the binder is an aqueous binder.

4. The method of any one of claims 2-3, wherein the second particulate feedstock comprises the second carbonaceous material comprising at least one of charcoal, wet petrol coke, wet recycled petrol coke, green (non-calcined) calcined petroleum cokes, green calcined cokes from bio-refineries, bituminous coals, calcined petrol coke, calcined cokes from bio-refineries, gilsonite, anthracite coal, pyrolysis coke, calcined biocoke, calcined HTC (hydrothermal carbon), biochar or mixtures thereof.

5. The method of any one of claims 2-4, wherein the second particulate feedstock comprises the titaniferous material, and optionally wherein the titaniferous material comprises at least one of titaniferous slags, natural rutiles, synthetic rutiles, ilmenites, and mixtures thereof.

6. The method of any one of the previous claims, further comprising: obtaining wet petrol coke, wet recycled petrol coke or mixtures thereof from unreacted solids exhausted from a carbochlorination reactor in its standard operation mode of making TiCI4; and providing the wet petrol coke, the wet recycled petrol coke or mixtures thereof as the first particulate feedstock material to be mixed and extruded.

7. The method according to claims 2 to 6, wherein the first particulate feedstock comprises a first titaniferous material and the second particulate feedstock comprises a second titaniferous material, and optionally wherein the first and second titaniferous materials are selected from at least one of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites, and / or combinations thereof, and preferably selected from at least two of titaniferous slags, natural rutiles, synthetic rutiles, and ilmenites.

8. The method of any one of the previous claims, wherein the binder is an aqueous binder comprising any one of lignosulfonate, carbohydrates, including glycerin, sugar, molasses, starch, modified starch, cellulose, including carboxymethyl cellulose (CMC), functionalized lignocellulose, lignosulfonate, polyvinyl alcohol (PVA), water-based plasticizers, tannins, and inorganic binders including cement, bentonite, waterglass, aluminum hydroxide, metakaolin, and combinations thereof.

9. The method of any one of the previous claims,wherein the binder comprises 2- 20 wt.% of modified starch, preferably 3-10 wt.% of modified starch, and more preferably 3 - 5 wt.% of modified starch, and / or wherein the binder comprises 2-20 wt.% of waterglass, preferably 5-10 wt.% of waterglass, and more preferably 5 - 7 wt.% of waterglass, and / or wherein the binder comprises 1- 20 wt.% of aluminum hydroxide, preferably 1-6 wt.% of aluminum hydroxide, and more preferably 1-3 wt.% of aluminum hydroxide, wherein the wt.% is measured from the contents of the porous composite feedstock after drying.

10. The method of any one of the previous claims, wherein the stiff vacuum extrusion process is conducted under vacuum pressures above 5 mbar, preferably between 25-150 mbar, and more preferably between 50-100 mbar; and / or wherein the stiff vacuum extrusion process is conducted under dynamic pressure of the homogeneous mass acting on a perforated extrusion disc of a vacuum extrusion machine by a transport screw in a second stage of the vacuum extrusion machine ranging from 5 bar to 100 bar, preferably from 20 bar to 40 bar, and optionally wherein the extrudate exiting through the perforated extrusion disc has a diameter between 4-25 mm, preferably between 17-21 mm, and more preferably 19 mm, and optionally wherein the step of mixing is performed with a double shaft mixer.11 . The method of any one of the previous claims, wherein the stiff vacuum extrusion process is conducted under temperatures between 0°C and 80°C, preferably between 30°C and 50°C; and / orThe method of any one of the previous claims, wherein the porous composite particulate feedstock has a hardness of at least 0.8 N / mm2 or more, preferably more than 2.0 N / mm2; and / or wherein at least one of the first particulate feedstock and the second particulate feedstock has an average particle size (d50) less than 50 pm; and / or wherein the first particulate feedstock and the second particulate feedstock have average particles sizes (d50) between 20 pm to 500 pm, and preferably between 50 pm to 300 pm; and / or wherein at least one of the first particulate feedstock and the second particulate feedstock has a moisture content more than 1 wt.% during the mixing step; and / orwherein the sizing preferably includes at least one operation cycle of crushing and / or sieving the extrudate.

12. A composite feedstock for use in the carbochlorination process of making TiCI4 manufactured according to any one of the previous claims.

13. Use of the composite feedstock of claim 12 in the carbochlorination process of making TiCI4 in a fluidized bed reactor by supplying the composite feedstock into the fluidized bed reactor during the carbochlorination process.