Titanium Dioxide Recovery Process

Abstract

PROCESS FOR RECOVERING TITANIUM DIOXIDE. Process for recovering titanium dioxide from a titanium-containing material, the process including the steps of: leaching the titanium-containing material in a first leaching step at atmospheric pressure and at a temperature of 70 to 97°C with a first leach to produce a first leaching solution comprising first undissolved leach solids which include a titanium content and a first leach liquor, the first leach comprising hydrochloric acid at a concentration of less than 23% w / w; separating the first leach liquor and the first undissolved leach solids;Leach the first leaching solids in a second leaching stage at atmospheric pressure and a temperature of 60 to 80°C with a second leach in the presence of a powdered Fe reducing agent to produce a second leaching solution comprising undissolved second leaching solids and a second leaching liquor that includes a leached titanium content and iron content, the second leach comprising a mixed chloride solution comprising less than 23% w / w hydrochloric acid and an additional chloride selected from alkali metal chlorides, magnesium chloride and calcium chloride, or mixtures thereof; separate the second leaching liquor and the undissolved second leaching solids; and then separate the titanium dioxide and iron content from the second leaching liquor by precipitation, and regenerate the second leach for recycling of the second leaching stage.

Description

1 / 87 Titanium Dioxide Recovery Process CROSS-REFERENCE OF PRIORITY

[001] The present invention claims priority from Australian Provisional Patent Application No. 2020901698 filed on May 26, 2020, the content of which is to be understood as incorporated into this descriptive report by this reference. TECHNICAL FIELD

[002] The present invention generally relates to a process for recovering titanium dioxide from a titanium-containing material. The invention is particularly applicable for recovering titanium dioxide from a titanium-containing ore or ore concentrate, and it will be convenient to describe the invention herein in relation to this exemplary application. However, it should be appreciated that the invention is not limited to this application and can be used to recover titanium dioxide from a variety of sources, including other mineral deposits containing titanium minerals, vanadium associated with titanium minerals such as titanomagnetite, vanadium-containing minerals, and titanium-containing leaching residues and slags. BACKGROUND OF THE INVENTION

[003] The following discussion of the background of the invention is intended to facilitate understanding of the invention. However, it should be noted that the discussion is not an acknowledgment or admission that any material referred to was published, known, or part of the general common knowledge as of the priority date of the application.

[004] Titanium is the ninth most abundant element, making up about 0.6% of the Earth's crust. A variety of titanium-containing minerals occur in nature, including Petition 870230008371, dated 01 / 31 / 2023, p. 17 / 103 2 / 87 Ilmenite (FeO·TiO2 or TiFeO3), rutile (T1O2), and leucoxene (Fe2O3·TiO2). Ilmenite, containing 40 to 65% TiO2, represents about 91% of the world's demand for titanium minerals. In 2019, world ilmenite production reached approximately 7 million metric tons. In addition to titanium, titanium-containing minerals typically contain other valuable metals, the content of which can vary widely in type and quantity depending on the ore source. A titanium-containing ore may contain one or more of vanadium, aluminum, manganese, magnesium, molybdenum, chromium, copper, lead, nickel, zinc, zirconium, niobium, and tantalum. These titanium-containing ores also typically include varying amounts of Fe2O3 and gangue materials, usually silicates, alumina, lime, and magnesia.

[005] Titanium-containing ore can be leached as is or beneficiated to produce a concentrate, beneficiation being employed if the ore has a low titanium content. Processes are known for recovering titanium dioxide from ilmenite and other titanium-containing ores. Most of these processes involve digesting the ore in a mineral acid, such as hydrochloric acid (the chloride process) or sulfuric acid (the sulfate process), to remove at least the titanium values ​​from the ore. In many of these processes, the purity of the titanium dioxide obtained can be around 90 to 95%, and therefore further purification procedures are necessary to produce a high-quality pigment-grade product.

[006] The sulfate process is carried out via a hydrometallurgical route and uses ilmenite or slag ores. Petition 870230008371, dated 01 / 31 / 2023, page 18 / 103 3 / 87 of low-grade titanium (72 to 87% TiO2) as raw materials, where the product quality remains inferior and the process generates large amounts of waste. In contrast, the chloride process traditionally treats only high-quality synthetic rutile (90–95% TiO2), natural rutile (95% TiO2), or high-quality titanium slag (>90% TiO2) through a complex process to produce purer products with relatively less waste generation.

[007] The hydrometallurgical processing of ilmenite ores with hydrochloric acid has been the main focus of recent research. Several processes have been proposed using i) direct leaching, ii) leaching in the presence of an oxidizing agent, iii) leaching in the presence of a reducing agent, such as iron powder, and iv) leaching after pre-oxidation of the concentrate at high temperature. The leachate is typically HCl-based, either with a high concentration of HCl (30 to 40% w / w) or with the optional addition of a chloride species, such as MgCl2, which has been found to improve direct leaching processes.

[008] An important issue for the HCl leaching route for any ore / mineral / concentrate is the cost of HCl and therefore its regeneration from the process liquor to ensure the process is economically viable. To regenerate HCl from the process liquor, pyrohydrolysis techniques (e.g., International Patent Publication No. WO 2014 / 125275 A1) or high-temperature hydrolysis (e.g., International Patent Publication No. WO 2011 / 094858) are used. Both processes are energy-intensive, requiring high temperatures: 400 to Petition 870230008371, dated 01 / 31 / 2023, page 19 / 103 4 / 87 800°C for decomposition by pyrohydrolysis, where metal chloride salts are decomposed into metal oxide; and 170 to 180°C for high-temperature hydrolyses to allow the hydrothermal reaction to precipitate the remaining metals as metal oxide, for example, iron as hematite. Both processes also require expensive reactor construction materials due to the highly corrosive gaseous HCl produced at these temperatures.

[009] Another problem with the HCl leaching route is the method of recovering valuable metal. In several processes, valuable metals including titanium and iron are separated using the expensive solvent extraction (SX) technique (e.g., U.S. Patent No. 7803336). Incorporating the solvent extraction technique for Fe and Ti recovery into a process is a capital-intensive choice that can hinder the successful commercialization of the process.

[010] An example of a chloride process is taught in Canadian Patent Publication CA2878744 which includes, among other processes, a process for recovering titanium dioxide and valuable metals from a titanium-containing material using a two-stage chloride-based leaching process. The titanium-containing material may be, for example, chosen from a titanium-containing ore or a recycled industrial material containing titanium, such as slag, red mud or fly ash. A first leaching stage uses an HCl-based leachate with an HCl concentration of 25 to 45% w / w at a temperature of 125 to 225°C on a titanium-containing material comprising Ti, Si and a first metal to produce a first liquor of Petition 870230008371, dated 01 / 31 / 2023, page 20 / 103 5 / 87 Leaching of the first metal and a solid containing Si and Ti. The leaching liquor and the solid are separated using customized recovery processes to recover the first metal from the first leaching liquor. The Si and Ti-containing solid from the first stage undergoes a second leaching using a leaching agent containing less than 20% w / w HCl and at less than 85°C, in the presence of a chloride (MgCl2 or ZnCl2) to produce a second leaching liquor including TiCl4. Titanium is recovered as TiO2 by heating, solvent extraction and subsequent formation of titanium dioxide from said solvent extraction, or reacted with water, oxygen and / or a base to cause the precipitation of TiO2. The HCl from the leaching liquor is regenerated. The recovery of hematite (Fe2O3) from FeCl3, which may be present in the ore leaching liquor, can also be achieved using high-temperature hydrolysis at 160 to 175°C, generating HCl for recycling to the leaching stages.

[011] While CA2878744 provides versatile chloride leaching, the conditions of the first leaching stage provide non-ideal and capital-intensive conditions for the recovery of several important valuable metals, in particular, the high concentration of HCl leach and high temperature. Furthermore, the second leaching stage is conducted under conditions that require that the resulting metal values, including any iron content in the leach, be recovered in an energy-intensive manner.

[012] Another chloride process is taught in international patent publication WO2015 / 131266 which refers to a process for recovering high synthetic rutile Petition 870230008371, dated 01 / 31 / 2023, p. 21 / 103 6 / 87 quality (95 to 98% TiO2) of low-quality ores containing less than 12% TiO2. As per the previous patent publication, this process comprises a two-stage leaching in 35 to 40% w / w HCl with an acid-to-ore ratio of 2 to 2.5. The first leaching stage is carried out with ground ore with a particle size of 80% less than 200 mesh at 60 to 70°C. The second leaching stage is carried out with the residue from the first stage at 75 to 80°C. The leaching liquors from both leaching stages, after solid-liquid separation, are combined and boiled to distill the unreacted HCl until the dissolved titanium is hydrolyzed and a substantial portion of the iron chlorides precipitates as hydrate. After filtering the hydrolyzed titanium paste with iron chloride crystals, the crystals are dissolved in a minimum of dilute HCl, leaving the insoluble TiO(OH)2, which is calcined to obtain 95 to 98% TiO2 product.The Ti-free liquor obtained after the Ti hydrolysis step is further treated to recover V and Cr separately by means of solvent extraction or selective precipitation. The HCl leachate is regenerated using a spray reactor to undergo high-temperature hydrolysis in a slightly oxidizing atmosphere to produce iron oxide and HCl for iron and hydrochloric acid recovery. However, once again, several valuable metal recovery processes, including iron recovery and the HCl regeneration stage, consume a great deal of energy.

[013] It would therefore be desirable to provide an improved or at least alternative process for recovering titanium / titanium dioxide from a titanium-containing material, Petition 870230008371, dated 01 / 31 / 2023, page 22 / 103 7 / 87 such as ores or concentrates containing titanium. SUMMARY OF THE INVENTION

[014] A first aspect of the present invention provides a process for recovering titanium dioxide from a titanium-containing material, the process including the steps of: Leach the titanium-containing material in a first leaching step at atmospheric pressure and a temperature of 70 to 97°C with a first leach to produce a first leaching solution comprising first undissolved leaching solids that include a titanium content, preferably substantially all the titanium content of the titanium-containing material, and a first leaching liquor, the first leach comprising hydrochloric acid at a concentration of less than 23% w / w; separate the first leaching liquor and the first undissolved leaching solids; leach the first leaching solids in a second leaching stage at atmospheric pressure and a temperature of 60 to 80°C with a second leaching agent in the presence of a powdered Fe reducing agent to produce a second leaching solution comprising undissolved second leaching solids and a second leaching liquor that includes a leached titanium content and an iron content, the second leaching agent comprising a mixed chloride solution comprising less than 23% w / w hydrochloric acid and an additional chloride selected from alkali metal chlorides, magnesium chloride and calcium chloride, or mixtures thereof; separate the second leaching liquor and the second undissolved leaching solids; Petition 870230008371, dated 01 / 31 / 2023, page 23 / 103 8 / 87 Precipitate titanium dioxide from the second leaching liquor by adding heated or boiling water under an inert gas or nitrogen atmosphere to raise the temperature of the second leaching liquor to 85 to 100°C to produce a treated second leaching liquor and a solid containing titanium dioxide; to separate the solid containing titanium dioxide from the second treated leaching liquor; to precipitate the iron content of the second treated leaching liquor by adding a neutralizing agent and an oxidizing agent to the second treated leaching liquor at a temperature of 70 to 90°C to increase the pH of the second leaching liquor to 4 to 8 to produce a paste with removed iron comprising a second leaching liquor with removed iron and a precipitated solid containing iron; Separate the second leaching liquor containing the removed iron from the precipitated iron solid; and regenerate the second leachate for recycling to the second leaching stage; thus recovering the titanium from the second leaching solution as titanium dioxide. Two-stream leaching process

[015] The process of the present invention relates to a two-stream leaching process using hydrochloric acid leaching followed by mixed hydrochloric acid and calcium chloride leaching which, firstly, selectively leaches impurities and valuable metals (such as vanadium and aluminum) other than titanium from the titanium-containing material in the first leaching step and then selectively leaches the titanium content of the Petition 870230008371, dated 01 / 31 / 2023, page 24 / 103 9 / 87 titanium-containing material in a second leaching stage that can then be recovered. This dual leaching process strategy results in a more effective leaching process that specifically targets titanium in the second leaching stage, compared to previous single-stage leaching processes where titanium is dissolved from ore materials along with impurities in a single-stage leaching.

[016] It is important to emphasize that the second leaching stage is carried out under a reducing atmosphere using metallic Fe powder. The reducing conditions provide the advantage of greater extraction of Ti from Ti minerals, such as ilmenite, rutile, pseudo-rutile, anatase and the like, from the first leaching solids and, therefore, from the titanium-containing feed material. In this leaching stage, the addition of iron powder aims to assist in the dissolution of the titanium-containing minerals.The removal of this iron content is done by precipitating iron from a ferrous chloride solution and an oxidant (e.g., alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid, an oxygen-containing gas such as air or oxygen, other non-sulfur-containing oxidants, or mixtures thereof) and a neutralizing agent (such as limestone, lime, or MgO), thus precipitating the iron, typically in the form of one or more goethite (α-FeOOH), akaganeite (β-FeOOH), hematite (Fe2O3), magnetite (Fe3O4), or a mixture thereof, or preferably, only as magnetite. The iron removal method of the present... Petition 870230008371, dated 01 / 31 / 2023, page 25 / 103 The invention offers significant advantages over conventional iron removal techniques, which typically focus on more expensive removal techniques (higher operating costs), such as pyrohydrolysis of hydrated ferrous chloride or high-temperature hydrolysis of ferric chloride in hematite (Fe2O3).

[017] It should be appreciated that titanium-containing material can be any material, including material containing titanium species comprising one or more of: a. an ore material containing titanium, including titanium-containing ore or mineral deposit, concentrate thereof, modified ore thereof and tailings thereof, and mixtures thereof; b. mineral deposit containing titanium minerals, such as ilmenite, rutile and / or leucoxene; c. vanadium associated with titanium minerals, such as titanomagnetite, minerals containing vanadium; d. a titanomagnetite ore or mineral deposit, concentrate thereof, modified ore thereof and tailings thereof, and mixtures thereof; e. leaching residues containing titanium and slag; or f. mineral processing waste.

[018] In preferred embodiments, the titanium-containing material is a titanium-containing ore, titanium-containing ore concentrate, modified titanium-containing ore tailings, or a mixture thereof. In some embodiments, the titanium-containing material is a titanium ore, a concentrate thereof, modified titanium ore and tailings thereof, or mixtures thereof. In these Petition 870230008371, dated 01 / 31 / 2023, page 26 / 103 In 11 / 87 embodiments, the titanium and iron values ​​are leached from titanium-containing ore material. In embodiments, the titanium-containing material includes ilmenite. However, it should be appreciated that the titanium-containing material may include other titanium minerals, including (but not limited to) rutile, pseudo-rutile, anatase, and / or leucoxene.

[019] The titanium-containing ore material may be ore itself, but preferably a concentrate thereof. Techniques for treating titanium-containing ore, such as ilmenite ore, to form a concentrate or for ore beneficiation, are well known in the art and include the use of gravity or magnetic separation steps. The process is preferably operated with an ore concentrate. In other embodiments, the ore may have been subjected to a smelting step in the presence of carbon and / or fluxes, after which a slag is separated from the smelting process and subjected to a leaching step. Thus, the ore may be in the form of a matte, for example, converter matte or liquid furnace matte. The ore may also be in the form of concentrates containing roasted and / or reduced titanium or other intermediates, all of which, including the matte discussed above, are referred to herein as modified ores.The ore may also be in the form of tailings from a titanium-containing ore. It is understood that the term ore also includes any other form of the ore and that mixtures of the various forms of the ore may be used. The process of the present invention can be operated without pretreatment of the titanium-containing ore. In particular, the process can be operated with or without roasting or reduction of the ore. Petition 870230008371, dated 01 / 31 / 2023, page 27 / 103 12 / 87

[020] Pretreatment of the ore, for example, oxidation and / or reduction of the ore, is normally not necessary before leaching. The process operates with a relatively low concentration of hydrochloric acid, especially with the hydrochloric acid concentration being less than 23% w / w (weight ratio). The process can be described as a direct process for leaching and recovery of titanium, as no pretreatment of the ore is necessary, and the leaching step produces a solution of titanium values. The process of the present invention is considered environmentally friendly, not requiring extensive pretreatment procedures. First stream of the leaching process

[021] The process of the present invention is a two-stream process for treating titanium-containing material, where each process stream can be operated independently on its own, having the respective recovery of dissolved valuable metals and regeneration of leachate.

[022] The first leaching step is primarily aimed at separating any hydrochloric acid-soluble impurities and valuable metals, such as vanadium, aluminum, and iron, that may be present in the titanium-containing material, leaving substantially the titanium content in the first leaching solids. The leaching step is carried out at atmospheric (ambient) pressure, i.e., it is not necessary to conduct the leaching step under pressure. Leaching is carried out under conditions such that the titanium leached from the titanium-containing ore material remains substantially in the titanium-containing material (the solid), i.e., the titanium does not leach into the solution. In this Petition 870230008371, dated 01 / 31 / 2023, page 28 / 103 In step 13 / 87, the leaching conditions are selected to leach most of the vanadium and aluminum content from the titanium-containing material into solution. Therefore, no titanium extraction and recovery step is required in the associated processing stream. To achieve this, the first leaching step is carried out with the first leach comprising less than 23% w / w HCl solution, preferably 20 to 22% w / w. The leaching temperature is between 70 and 97°C, and preferably between 85 and 97°C.

[023] The first leaching step can be conducted continuously as a co-current step, a countercurrent step or otherwise, or the leaching step can be conducted as a batch step.

[024] A solution rich in valuable metals (first leaching liquor) is obtained in the first leaching stage. The residue (first undissolved leaching solids) may be in the form of a suspension. The leaching mixture is fed to a solid / liquid separation stage to effect the separation of the first leaching liquor from the first leaching solids, for example, leaching residues and other gangue. Techniques for such separation are known in the field, for example, using a pressure or vacuum filter, countercurrent decantation, thickener or centrifuge.

[025] The titanium-containing material may also include one or more metals of added value, such as iron, vanadium, manganese, magnesium, or aluminum. Other trace elements, species, or impurities may also be present. The process of the present invention may therefore include steps for removing and recovering any iron, vanadium, Petition 870230008371, dated 01 / 31 / 2023, p. 29 / 103 14 / 87 manganese, magnesium, or aluminum from the leaching liquor in this first leaching processing stream. In these embodiments, the first leaching liquor is subjected to steps to recover at least one valuable metal from it.

[026] In exemplary embodiments, the valuable metals in the titanium-containing material include at least vanadium and / or aluminum. In such embodiments, the process further comprises a vanadium and / or aluminum removal step comprising: adding a neutralizing agent, preferably at least one of limestone, lime or MgO, to the first leaching liquor at a temperature of 50 to 80°C under an inert gas or nitrogen atmosphere, to raise the pH of the liquor to 3 to 6, thereby precipitating vanadium and aluminum to produce a V / Al removed slurry; and separating the V / Al removed slurry into a liquid fraction comprising a V / Al removed liquor and a solid fraction comprising the V / Al precipitated solid.

[027] The separation of vanadium and / or aluminum from the first leaching liquor is therefore a precipitation technique resulting from an elevation of the liquor pH caused by the addition of limestone, lime or MgO. In comparison, most prior technique processes separate vanadium using more expensive solvent extraction techniques.

[028] This stage of the process is preferably carried out under an inert gas or nitrogen atmosphere, preferably under a nitrogen blanket to prevent the oxidation of ferrous iron to ferric iron and to prevent the precipitation of any iron content (in the form of ferric iron) that may be in the first leaching liquor. The precipitation of vanadium and / or Petition 870230008371, dated 01 / 31 / 2023, page 30 / 103 15 / 87 aluminum is preferably conducted before the removal / recovery of other valuable metals that may be present in the first leaching liquor.

[029] Vanadium and aluminum recovery from the V / Al precipitated solid can be carried out by any suitable method known in the art, for example, by leaching using an ammonia or HCl solution, followed by precipitation and optional calcination steps. The details of these process steps are described in more detail later in the descriptive report.

[030] As noted above, the titanium-containing material may include an iron content (i.e., one of the valuable metals), for example, where the titanium-containing material is a titanium ore or concentrate thereof. Alternatively, or in addition, the first leaching liquor may include an iron content from the addition of Fe at some point in the first stream of the leaching process. In such embodiments, Fe powder is added because Fe(III) is present in the leaching liquor. The Fe powder reduces Fe(III) to Fe(II), and Fe(II) does not precipitate and remains in solution during the V / Al reduction due to the nitrogen mantle. In these embodiments, the process may further comprise an iron removal step comprising: Add a neutralizing agent and an oxidizing agent to the first leaching liquor at a temperature of 70 to 90°C to increase the pH of the liquor to 4 to 7, thereby precipitating the iron to produce a paste with the iron removed; and separate the paste with the iron removed into a liquid fraction comprising a liquor with the iron removed and a solid fraction comprising the precipitated iron solid. Petition 870230008371, dated 01 / 31 / 2023, page 31 / 103 16 / 87

[031] The neutralizing agent may comprise any suitable neutralizing species or compound, and preferably comprises at least one of limestone, lime or MgO.

[032] The oxidant may comprise an alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid, an oxygen-containing gas such as air or oxygen, other non-sulfur-containing oxidants or mixtures thereof. Preferred oxidants are H2O2 or an oxygen-containing gas such as oxygen, air or the like. The most preferred oxidant is oxygen or air.

[033] The iron removal solid may comprise one or more of magnetite, goethite, hematite, and akageneite. However, magnetite is the preferred form for the iron removal solid. Thus, in exemplary embodiments, the iron is substantially precipitated as magnetite, preferably precipitated only as magnetite. The iron precipitate, preferably mainly magnetite, can be used to produce Fe powder, for example, by reacting the precipitated magnetite with carbon / charcoal / coke / coal at high temperature, ~800 to 1000°C. The Fe powder produced can be recycled for use in the process, for example, in the second leaching process stream or in the optional reduction step of the first leaching process stream.

[034] In the first general stream of the leaching process, the iron removal step is preferably, Petition 870230008371, dated 01 / 31 / 2023, page 32 / 103 17 / 87 performed after the vanadium and / or aluminum removal stage.

[035] The titanium-containing material may also include manganese and / or magnesium (i.e., one of the valuable metals). Alternatively, or in addition, the first leaching liquor may include a manganese and / or magnesium content from the addition of Mg or Mn at some point in the first leaching process stream, for example, the addition of MgO. In these embodiments, the process still comprises a manganese and / or magnesium removal step comprising: Add a neutralizing agent, lime, and an oxidant, preferably H2O2 or an oxygen-containing gas, more preferably air, to the liquor removed with iron at a temperature of 60 to 90°C to increase the pH of the liquor to 9 to 10, thereby precipitating Mg and / or Mn to produce a paste with the Mg / Mn removed; and separate the paste with the Mg / Mn removed into a liquid fraction comprising a liquor removed with Mg / Mn and a solid fraction comprising the precipitated Mg and / or Mn solid.

[036] The precipitation step is carried out in the presence of an oxidant, which may preferably be H2O2 or an oxygen-containing gas, such as oxygen, air or similar, for the oxidation of Mn(II) to Mn(IV). In this step, lime is preferably used as the neutralizing agent. The precipitated Mg and / or Mn solid will typically comprise Mg(OH)2 and a mixture of Mn oxide / hydroxide. The liquor removed with Mg / Mn will mainly be a chloride solution, for example, calcium chloride, where limestone and / or lime are used in the previous steps. In the first general stream of the leaching process, the manganese and / or magnesium removal step is preferably carried out after the Petition 870230008371, dated 01 / 31 / 2023, page 33 / 103 18 / 87 iron removal stage.

[037] To aid in process economy, it is preferable that the first leachate be regenerated and recycled for the first leaching stage. In these modalities, the process also includes: Regenerate the first leachate and recycle the first leachate for the first leaching stage.

[038] In modalities, the first leachate is regenerated by: To concentrate the chloride content of the liquor removed with Mg / Mn by removing water, preferably by boiling and / or evaporation, to produce an evaporated liquor; react the evaporated liquor with at least 98% w / w sulfuric acid at a temperature of 30 to 90°C, preferably 80 to 85°C under atmospheric conditions, to produce 20 to 22% w / w hydrochloric acid and a solid precipitate; Separate the precipitated solid and the hydrochloric acid liquor; and recycle the hydrochloric acid liquor for the first leaching stage.

[039] The composition of the chloride content will depend on the composition of the additives to this first stream of the leaching process. In many cases, the chloride content will comprise a calcium chloride solution / liquor. The evaporated liquor will therefore comprise a calcium chloride liquor. In such embodiments, the evaporated liquor is reacted with concentrated sulfuric acid (98% w / w) at a stoichiometric ratio of calcium chloride to sulfuric acid to produce HCl and a precipitate comprising at least one of gypsum, hemihydrate or an anhydride compound. In addition Petition 870230008371, dated 01 / 31 / 2023, page 34 / 103 19 / 87 Furthermore, in these methods, the reaction between the evaporated liquor and the concentrated sulfuric acid is preferably carried out in a temperature range of 80 to 85°C in order to precipitate only anhydride.

[040] The first leaching process stream preferably includes a series of treatment processes prior to the valuable metal recovery steps, more particularly prior to the vanadium and / or aluminum precipitation step. In these embodiments, the process further comprises the following steps prior to the precipitation of vanadium and / or aluminum from the first leaching liquor: Neutralize at least part of the free acid (HCl) in the first leaching liquor by adding to the first leaching liquor at least one of: titanium-containing feed material (preferably titanium ore concentrate), limestone, lime, or MgO, to produce a first neutralized liquor paste including a neutralized leaching solid; and separate the first neutralized liquor paste into a solid fraction comprising the neutralized leaching solid and a liquid fraction comprising the first neutralized leaching liquor.

[041] It should be appreciated that other neutralizing agents may also be used, such as sodium hydroxide or similar. In some embodiments, the first stage of neutralization of solid leaching liquor or leaching solids (when ore is used) is fed into the first leaching stage.

[042] The first leaching process stream preferably includes the following steps after the steps Petition 870230008371, dated 01 / 31 / 2023, page 35 / 103 20 / 87 neutralization: Reduce the first leaching liquor neutralized at 45 to 75°C by adding metallic iron, preferably iron powder, to convert ferric chloride in the first leaching liquor into ferrous chloride; and separate the reduced first leaching liquor into a liquid fraction comprising a reduced liquor and a solid fraction comprising any unreacted solid iron powder.

[043] The reduction is preferably carried out under an inert gas or nitrogen atmosphere, preferably under a nitrogen mantle, and achieves an oxidation-reduction potential (ORP) of the liquor below 100 mV. Second stream of the leaching process

[044] The second leaching stage and the associated second leaching process stream are substantially focused on the effective recovery of titanium in the form of titanium dioxide (rutile or anatase). The specific recovery steps and conditions depend on the composition of the titanium-containing material and therefore on the processes required to recover the titanium dioxide and regenerate the leachate used in the second leaching stage.

[045] The second leaching stage is carried out at atmospheric (ambient) pressure, i.e., it is not necessary to conduct the leaching stage under pressure. Leaching is carried out under conditions such that the titanium leached from the titanium-containing ore material is leached into solution and remains in solution during leaching, i.e., the titanium does not precipitate as, for example, titanium dioxide. In particular, leaching is carried out at a temperature of less than or equal to 80°C, typically between 60 and 80°C and higher. Petition 870230008371, dated 01 / 31 / 2023, page 36 / 103 21 / 87 preferably, at a temperature in the range of 70 to 80°C. Leaching is carried out with the second leach in the presence of a powdered Fe reducing agent. The second leaching stage is preferably conducted for 2 to 6 hours, in some embodiments, 4 to 6 hours.

[046] The second leaching stage can be conducted continuously as a co-current stage, a countercurrent stage or otherwise, or the leaching stage can be conducted as a batch stage.

[047] The second leach comprises a mixed chloride solution comprising less than 23% w / w hydrochloric acid and an additional chloride selected from alkali metal chlorides, magnesium chloride and calcium chloride, or mixtures thereof. In embodiments, the mixed chloride solution comprises 20 to 22% w / w HCl and the additional chloride has a total chloride concentration of 400 to 550 g / L (calculated based on the amounts of chloride and hydrochloric acid in the leach solution). It should be appreciated that the metal chloride / HCl (metal to hydrochloric acid) ratio in the leach is preferably adjusted to optimize leaching, based for example on the particular ore being leached and the temperature. The upper limit of the chloride concentration may depend on the ions present in the leach solution, especially as a result of ore leaching and the resulting complex formation.

[048] In the second leaching stage, the additional chloride is selected from alkali metal chlorides, magnesium chloride and calcium chloride, or mixtures thereof. In exemplary embodiments, the chloride is preferably calcium chloride, so that hydrochloric acid is regenerated and Petition 870230008371, dated 01 / 31 / 2023, page 37 / 103 22 / 87 a mixed chloride solution containing hydrochloric acid and unreacted calcium chloride is recycled in the process. However, it should be appreciated that other chlorides, such as magnesium chloride, can also be used.

[049] In particularly preferred embodiments of the invention, the chloride is derived from calcium chloride and hydrochloric acid, and the chloride concentration of 400 to 550 g / L is calculated based on the amounts of calcium chloride and hydrochloric acid in the leaching solution. In the embodiments, the amount of hydrochloric acid is in the range of 255 to 280 g / L and the amount of calcium chloride is in the range of 300 to 400 g / L. For clarity, a concentration of 255 to 280 g / L of HCl provides ~20 to 22% w / w of HCl in a mixed chloride solution of HCl and CaCl2, where the SG liquor is quite high ~1.3. In the case of water in HCl, 20 to 22% w / w of HCl will be ~220 g / L to 240 g / L of HCl.

[050] A solution rich in valuable metal (second leaching liquor) is obtained in the second leaching stage. The residue (second undissolved leaching solid) may be in the form of a suspension. The leaching mixture is fed to a solid / liquid separation stage to effect the separation of the second leaching liquor from the second leaching solids, for example, leaching residue and other gangue. Techniques for such separation are known, for example, using a pressure or vacuum filter, countercurrent decantation, thickener or centrifuge.

[051] For example, when the titanium-containing material is a titanium-containing ore or a concentrate thereof, the first leaching solid will normally contain Petition 870230008371, dated 01 / 31 / 2023, page 38 / 103 23 / 87 primarily titanium-containing minerals, such as ilmenite and any precipitated rutile, pseudo-rutile, anatase, etc., along with gangue minerals that remained undissolved during the first leaching. The leaching conditions in this second leaching stage can be adapted to aid the dissolution of each of these titanium-containing minerals. Thus, in some embodiments, the second leaching stage includes two leaching regimes, comprising: A first leaching regime was carried out in a mixed chloride solution (without any addition of iron powder); and a second leaching regime was carried out in a mixed chloride solution with the addition of iron powder.

[052] The second leaching reaction can be carried out as a two-stage reaction. Here, the first leaching regime and the second leaching regime of the second leaching stage can be conducted as successive leaching stages in (i) the same leaching stage / vessel; or (ii) separate leaching stages / vessels. In embodiments, the first leaching regime is carried out for 1 to 2 h and the second leaching regime for 1 to 4 h. In some embodiments, the first leaching regime is carried out for 1 to 2 h and the second leaching regime for 2 to 4 h.

[053] The first leaching regime is used to dissolve most of the ilmenite mineral. The second leaching regime with Fe aims to dissolve the remaining unreacted ilmenite and other minerals containing Ti or solid precipitate from the first leaching stage, such as rutile, pseudo-rutile, anatase or similar, under the atmosphere. Petition 870230008371, dated 01 / 31 / 2023, page 39 / 103 24 / 87 reducing agent. The iron powder will also reduce the ferric iron present in the leaching liquor to ferrous iron during the leaching reaction. If necessary, a small additional amount of fresh second leaching agent (mixed chloride solution) can be added in the second stage of the second leaching to stabilize the dissolved metals and the additional iron from the added Fe powder.

[054] After leaching, the second stream of the leaching process includes processes for recovering dissolved titanium and iron from the leaching liquor and regenerating the mixed HCl and CaCl2 leaching solution.

[055] The iron content of the second treated leaching liquor is removed by adding a neutralizing agent and an oxidizing agent to the removed V / Al liquor at a temperature of 70 to 90°C to increase the pH of the liquor to 4 to 8, thereby precipitating iron to produce a paste with removed iron; and separating the paste with removed iron into a liquid fraction comprising a removed liquor with iron and a solid fraction comprising a precipitated solid of iron. The neutralizing agent may comprise any suitable neutralizing species or compound and preferably comprises at least one of limestone, lime or MgO.The oxidant may comprise one of alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid, an oxygen-containing gas such as air or oxygen, other non-sulfur-containing oxidants, or mixtures thereof. Preferred oxidants are H2O2 or an oxygen-containing gas such as oxygen, air, or the like. Petition 870230008371, dated 01 / 31 / 2023, page 40 / 103 25 / 87 The most preferred oxidant is oxygen or air. The iron removal solid may comprise one or more of magnetite, goethite, hematite, and akageneite. However, magnetite is the preferred form for the iron removal solid. Again, in exemplary embodiments, the iron is substantially precipitated as magnetite, preferably precipitated only as magnetite.

[056] The iron precipitate, preferably mainly magnetite, can be used to produce Fe powder, for example, by reacting the precipitated magnetite with carbon / charcoal / coke / coal at high temperature, ~800 to 1000°C. The Fe powder produced can be recycled for use in the process, for example, in the second leaching process stream or in the optional reduction step of the first leaching process stream.

[057] In some embodiments, the titanium content of the second leaching liquor may include a Ti(III) content. To recover titanium dioxide, it is preferable that any Ti(III) content be converted to Ti(IV) before the titanium dioxide precipitation step. In these embodiments, the process therefore still comprises the step of: Introduce an oxidant into the second leaching liquor before the titanium dioxide precipitation step to oxidize any Ti(III) content to Ti(IV) by controlling the oxidation-reduction potential of the second leaching liquor within 100 to 200 mV; where the oxidant is selected from air, oxygen, alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, hypochlorite Petition 870230008371, dated 01 / 31 / 2023, page 41 / 103 26 / 87 alkali metal, hydrogen peroxide, perchloric acid, other non-sulfur-containing oxidants, or mixtures thereof.

[058] Examples of alkali metal peroxides are sodium peroxide and potassium peroxide. Examples of alkali metal perchlorates are sodium perchlorate and potassium perchlorate. Ammonium perchlorate, magnesium perchlorate, and magnesium chlorate may also be used. Examples of alkali metal chlorates are sodium chlorate and potassium chlorate. An example of an alkali metal hypochlorite is sodium hypochlorite. Other oxidants are sulfur-free oxidants; the presence of sulfur in oxidants should be avoided. Preferred oxidants are selected from the group consisting of air, oxygen, chlorine, sodium chlorate, sodium perchlorate, hydrogen peroxide, perchloric acid, and mixtures thereof. In exemplary embodiments, the oxidant comprises hydrogen peroxide and, in some embodiments, dilute hydrogen peroxide.

[059] Subsequently, titanium dioxide can be recovered using a precipitation step in which heated or boiling water is added to the second leaching liquor under an inert gas or nitrogen atmosphere to raise the temperature of the second leaching liquor to 85 to 100°C to produce a treated second leaching liquor and a solid containing titanium dioxide. This titanium dioxide precipitation step preferably comprises hydrolyzing the Ti(IV) content of the second leaching liquor to precipitate titanium dioxide (TiO2) as a solid. The reaction is carried out under an inert gas or nitrogen atmosphere (such as a nitrogen mantle) to avoid Petition 870230008371, dated 01 / 31 / 2023, page 42 / 103 27 / 87 The oxidation of ferrous iron to ferric iron and the precipitation of ferric iron with TiO2 during the TiO2 washing stages. The hydrolysis of Ti(IV) will release HCl into the solution. In embodiments, the HCl can be partially neutralized by adding at least one slurry of limestone, lime, or MgO to maximize the recovery of TiO2.

[060] Ferrous iron liquor can be subjected to optional V / Al removal depending on the concentrations of V and / or Al in the precipitated TiO2 liquor, adopting the same procedure as explained for the first stream of the leaching process. In these embodiments, the second stream of the leaching process still comprises the steps of: Add a neutralizing agent, preferably at least one of limestone, lime or MgO, to the second treated leaching liquor at a temperature of 50 to 80°C under an inert gas or nitrogen atmosphere, to increase the pH of the liquor to 3 to 6, thereby precipitating the vanadium and aluminum to produce a V / Al removed paste; and separate the V / Al removed paste into a liquid fraction comprising a second treated V / Al removed leaching liquor and a solid fraction comprising the V / Al precipitated solid.

[061] Again, V / Al removal is carried out under an inert gas or nitrogen atmosphere, preferably under a nitrogen mantle to prevent the oxidation of ferrous iron to ferric iron and the precipitation of ferric iron in this step.

[062] As previously noted for the first leaching process stream, vanadium and aluminum recovery from the V / Al precipitated solid can be carried out Petition 870230008371, dated 01 / 31 / 2023, page 43 / 103 28 / 87 by any suitable method known in the art, for example, leaching using an ammonia or HCl solution, followed by precipitation and optional calcination steps. The details of these process steps are described in more detail later in the descriptive report.

[063] Where applicable, Mg / Mn removal can also be applied to the second leaching stream. In these embodiments, the second process stream still comprises the following steps: Add a neutralizing agent, preferably lime, and an oxidizing agent, preferably H2O2 or an oxygen-containing gas, more preferably air, to the liquor removed with iron at a temperature of 60 to 90°C to increase the pH of the liquor to 9 to 10, thereby precipitating Mg and / or Mn to produce a paste with the Mg / Mn removed; and separate the paste with the Mg / Mn removed into a liquid fraction comprising a liquor removed of Mg / Mn and a solid fraction comprising the precipitated Mg and / or Mn solid.

[064] In this step, lime is preferably used as the neutralizing agent. The oxidant, preferably H2O2 or an oxygen-containing gas such as air, is added to assist the oxidation of Mn(II) to Mn(IV). The precipitated Mg and / or Mn solid will typically comprise Mg(OH)2 and a mixture of Mn oxide / hydroxide. The removed Mg / Mn liquor will be primarily a calcium chloride solution.

[065] To aid in process economy, the second leachate is regenerated and recycled for the second leaching stage. This regeneration stage of the second leachate for recycling to the second leaching stage preferably comprises: Petition 870230008371, dated 01 / 31 / 2023, page 44 / 103 29 / 87 concentrate the chloride content of the second treated leach liquor by removing water, preferably by boiling and / or evaporation, to produce a concentrated chloride solution (in some cases with a concentration lower than its saturation concentration); react the evaporated liquor with at least 98% w / w sulfuric acid at a temperature of 30 to 90°C, preferably 80 to 85°C under atmospheric conditions, to produce a mixed chloride solution with 20 to 22% w / w hydrochloric acid, an additional chloride content in the solution, and a solid precipitate; Separate the precipitated solid from the mixed chloride solution; and recycle the mixed chloride solution for the second leaching step.

[066] The composition of the chloride content will depend on the composition of the additives that were fed into this second stream of the leaching process. In many cases, the chloride content will comprise a calcium chloride solution / liquor. The evaporated liquor will therefore comprise a calcium chloride liquor. In such embodiments, the evaporated liquor comprises a calcium chloride liquor, in some cases with a concentration lower than its saturation concentration, and the evaporated liquor is reacted with concentrated sulfuric acid (98% w / w) at a stoichiometric ratio of calcium chloride to sulfuric acid to produce HCl and a precipitate comprising at least one of gypsum, hemihydrate or an anhydride compound.

[067] In the present invention, the HCl regeneration step typically concentrates at 20 to 22% w / w of HCl from the solution. Petition 870230008371, dated 01 / 31 / 2023, page 45 / 103 30 / 87 of CaCl2 is obtained by reacting it with concentrated H2SO4 at a temperature preferably above 75°C to produce mainly anhydride calcium sulfate or as a mixture of anhydride, calcium sulfate hemihydrate and dihydrate. In embodiments where the chloride content comprises calcium chloride, the reaction between the evaporated liquor and concentrated sulfuric acid is preferably carried out in a temperature range of 80 to 85°C aiming to precipitate only anhydride.

[068] The stages of the first leaching liquor treatment process and the second leaching liquor treatment process can be combined into at least one of the vanadium and / or aluminum removal stages; iron removal stage; or manganese and / or magnesium removal stage in some embodiments. In some embodiments, all or the stages common to the first leaching process stream and the second leaching process stream, including V / Al removal, Fe removal and Mg / Mn removal, are combined to run in a common process stream to reduce capital investment and also the cost of operation.

[069] It should be appreciated that the separation of solid and liquid elements in the process can be carried out using any suitable method. Techniques for such separation are known, for example, using a pressure or vacuum filter, countercurrent decantation, thickener or centrifuge.

[070] In some embodiments, the process of the present invention includes a sulfuric acid production plant that produces sulfuric acid from elemental sulfur. This Petition 870230008371, dated 01 / 31 / 2023, page 46 / 103 31 / 87 additional process can provide significant energy credit for power and heat generation required for various stages of the process.

[071] In some embodiments, the neutralizing agent in the various steps / stages of the process comprises MgO. In these embodiments, the process normally also comprises a Mg removal step, in which Mg(OH)2 is precipitated using lime and an MgO regeneration step, in which Mg(OH)2 is calcined, preferably at 300 to 400°C to regenerate MgO for recycling as the process neutralizing agent.

[072] A second aspect of the present invention provides a process system for recovering titanium dioxide from a titanium-containing material, the system including the steps of: a first leaching vessel for leaching the titanium-containing material in a first leaching step at atmospheric pressure and at a temperature of 70 to 97°C with a first leach to produce a first leaching solution comprising first undissolved leaching solids including a titanium content and a first leaching liquor, the first leach comprising hydrochloric acid at a concentration of less than 23% w / w; a first solid-liquid separator to separate the first leaching liquor and the first undissolved leaching solids; a second leaching vessel to leach the first leaching solids in a second leaching stage at atmospheric pressure and a temperature of 60 to 80°C with a second leach and a reducing additive of Fe powder to produce a second leaching solution comprising second undissolved leaching solids Petition 870230008371, dated 01 / 31 / 2023, page 47 / 103 32 / 87 and a second leaching liquor which includes a leached titanium content and iron content, the second leach comprising a mixed chloride solution comprising less than 23% w / w hydrochloric acid and an additional chloride selected from alkali metal chlorides, magnesium chloride and calcium chloride, or mixtures thereof; a second solid-liquid separator to separate the second leaching liquor and the undissolved second leaching solids; A first precipitation vessel is used to precipitate titanium dioxide from the second leaching liquor by adding heated or boiling water under an inert gas or nitrogen atmosphere to raise the temperature of the second leaching liquor to 85–100°C, producing a second treated leaching liquor and a solid containing titanium dioxide. to separate the solid containing titanium dioxide from the second treated leaching liquor; A second precipitation vessel precipitates the iron content of the second treated leaching liquor by adding a neutralizing agent and an oxidizing agent to the second treated leaching liquor at a temperature of 70 to 90°C to increase the pH of the second leaching liquor to 4 to 8 to produce a paste with removed iron comprising a second iron-removed leaching liquor and a precipitated iron solid; a third solid-liquid separator to separate the second leaching liquor with iron removed from the iron precipitate solid; and a regenerator stage to regenerate the second Petition 870230008371, dated 01 / 31 / 2023, page 48 / 103 33 / 87 leachate for recycling for the second stage of leaching; thus recovering the titanium from the second leaching solution as titanium dioxide.

[073] In this second aspect, the neutralizing agent added in the second precipitation vessel may comprise any suitable neutralizing species or compound and preferably comprises at least one of limestone, lime or MgO. In addition, the oxidant in the second precipitation vessel may comprise one of alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid, an oxygen-containing gas such as air or oxygen, other non-sulfur-containing oxidants or mixtures thereof. Preferred oxidants are H2O2 or an oxygen-containing gas such as oxygen, air or the like. The most preferred oxidant is oxygen or air.

[074] It should be appreciated that the process system of the second aspect of the present invention can perform the process of the first aspect of the present invention. The additional process features and steps / stages taught for the first aspect of the present invention apply equally to this second aspect of the present invention.

[075] A third aspect of the present invention provides a plant that includes a process according to the first aspect of the present invention.

[076] The present invention also provides in a fourth aspect a titanium dioxide produced from the process Petition 870230008371, dated 01 / 31 / 2023, p. 49 / 103 34 / 87 according to the first aspect of the present invention.

[077] Some advantages of this two-stage leaching process are as follows: i) The process of the present invention is based on atmospheric precipitation techniques below 100°C, which implies low capital investment compared to the process with high-temperature extraction processes and / or the solvent extraction process step; ii) No specialized construction material is required for the reactor design criteria in this process. Standard fiberglass and / or high-density polyethylene (HDPE) and / or polypropylene (PP) tanks can be used to meet the reactor / equipment requirements. Compared to the previous pyrohydrolysis technique or high-temperature hydrolysis technique, the leachate regeneration in the present invention is a simpler process where the energy requirement is low and the construction material is not critical (i.e., it does not require high-temperature operation and high-temperature corrosion-resistant materials); iii) The entire process operates with a low or reduced concentration of hydrochloric acid within a concentration range of 20 to 22% w / w HCl; iv) The HCl required in the process is regenerated from the process liquor containing calcium chloride under atmospheric conditions using sulfuric acid. BRIEF DESCRIPTION OF THE DRAWINGS

[078] The present invention will now be described with reference to the figures in the accompanying drawings, which illustrate particular preferred embodiments of the present invention, in Petition 870230008371, dated 01 / 31 / 2023, pp. 50 / 103 35 / 87 that: Figure 1 is a general flowchart showing the process steps for a preferred embodiment of the process according to the present invention; Figure 2 is a general flowchart showing the process steps for another embodiment of the process according to the present invention, which is a modified process flowchart of the process shown in Figure 1; Figure 3 is a general flowchart showing the process steps for another embodiment of the process according to the present invention, which is a modified process flowchart of the process shown in Figure 2, including the combined process steps; Figure 4 is a general flowchart showing the process steps for another embodiment of the process according to the present invention, which is a modified process flowchart of the process shown in Figure 3, including a second two-stage leaching step; Figure 5 provides a graph illustrating the extraction of Fe and Mg for 21% w / w and 17.5% w / w HCl primary leaching tests; Figure 6 provides a graph illustrating the extraction of V and Al for 21% w / w and 17.5% w / w HCl primary leaching tests; Figure 7 provides a graph illustrating the concentration of Ti during primary leaching with 21% w / w and 17.5% w / w HCl; Figure 8 provides a graph illustrating the online pH and ORP profile versus time for an Fe(III) reduction test at 70°C with 1.17 times the stoichiometric addition of sand. Petition 870230008371, dated 01 / 31 / 2023, p. 51 / 103 36 / 87 Faith; Figure 9 provides a graph illustrating the behavior of Fe precipitation from neutralized liquor precipitated with TiO2 at 80°C using limestone as a neutralizing agent and an air flow > 5 L / min; Figure 10 provides a graph illustrating the effect of temperature on Fe, V, and Ti extractions from titanomagnetite concentrate under leaching conditions of 20% w / w pulp density, 20.1% w / w HCl concentration, and 4 h; Figure 11 provides a graph illustrating the extraction of metals from titanomagnetite concentrate at 85°C for 2 h with a pulp density of 20.4% w / w and a 19.8% HCl solution; Figure 12 provides a graph illustrating the Ti analyses of the leaching liquors for the secondary leaching tests with the primary leaching residues. DETAILED DESCRIPTION

[079] The process of the present invention relates to the recovery of titanium dioxide from a titanium-containing material. The titanium-containing material can be any material, including material containing titanium species, such as titanium-containing ore. Titanium can be found in a variety of titanium-containing minerals, including ilmenite (FeO^TiO2 or TiFeO3), rutile (T1O2), anatase (TiO2) and / or leucoxene (Fe2O3^nTiO2). Such titanium-containing material may typically also include iron, vanadium, aluminum and manganese, which may also be solubilized in a leachate applied during a leaching step. The titanium-containing material may be a titanium-containing ore material including ore or deposit. Petition 870230008371, dated 01 / 31 / 2023, page 52 / 103 37 / 87 titanium-containing mineral, concentrate thereof, modified ore thereof and tailings thereof and mixtures thereof. The titanium-containing material may also be a material including vanadium associated with titanium minerals, such as titanomagnetite, vanadium-containing minerals and titanium-containing leaching residues and slags. However, it should be appreciated that the invention should not be limited to any of these materials and may comprise other materials that include a titanium content or titanium species.

[080] The process described in the present invention is a two-stream leaching process (designated Stream-1 and Stream-2 in Figure 1 and the associated description) for treating titanium-containing ore, concentrate, etc., where each stream can be operated independently on its own with the respective recovery of dissolved valuable metals and HCl leach regeneration. A process is described for recovering valuable metals including titanium, vanadium, aluminum, and iron from titanium-containing feed materials through leaching with hydrochloric acid (HCl) and a mixed solution of hydrochloric acid and additional chloride leaching. The overall process is described to operate at a reduced HCl concentration, below 23% w / w HCl, through the two streams of the leaching process.

[081] Figure 1 shows the general flowchart of an embodiment of the process of the present invention showing a two-stage leaching process 100 for the recovery of titanium dioxide from a titanium-containing ore or ore concentrate 101. As discussed above, the titanium-containing ore or ore concentrate 101 includes Petition 870230008371, dated 01 / 31 / 2023, page 53 / 103 38 / 87 titanium and, in this case, additional value metals, including iron, vanadium, manganese, magnesium, and aluminum. The process described and illustrated has been adapted to recover the titanium content and each of these valuable metals. It should be appreciated that different process steps can be used depending on the value metal composition of a given titanium-containing material. The process of the present invention may therefore include, but should not be strictly limited to, the following steps. Stream-1 (First leaching process stream)

[082] The process for the first leaching process stream 110 (Stream-1) is as follows: (i) A first leaching step 120 of the titanium-containing material, in this embodiment a titanium-containing ore 101, is conducted in a first leaching solution comprising 20 to 22% w / w HCl at 70 to 97°C, preferably at 85 to 97°C, to leach impurities, including vanadium, leaving the titanium content in the first leaching solid (solid leaching residue). The leaching process is followed by solid-liquid separation (part of step 120) of the first leaching slurry to separate the first leaching solids 125 and the first leaching liquor 126. The first leaching solid 125 will mainly contain Ti-containing minerals, such as ilmenite and any precipitated rutile, pseudo-rutile, anatase, etc. along with the gangue minerals that remained undissolved during the first leaching. The first leaching solid 125 is subsequently treated in the second leaching process stream 210 (Stream-2), described in more detail below; Petition 870230008371, dated 01 / 31 / 2023, p. 54 / 103 39 / 87 ii) The excess free acid (HCl) remaining in the first leaching liquor 126 after the first leaching is preferably neutralized in the neutralization stage 130 conducted at a temperature of 70 to 97°C. Here, the first leaching liquor 126 is fed into a neutralization vessel, a neutralizing agent 131 is added to minimize the concentration of free acid in the first leaching liquor below 5 g / L (pH < 0.5). The neutralizing agent 131 is preferably a feed of Ti-containing ores or concentrate to minimize the concentration of free acid in the first leaching liquor 126. However, another neutralizing agent, such as limestone, MgO lime, may be used, with the understanding that reagent consumption may be high to achieve the required pH.However, the initial neutralizing agent 131 is preferably a feed of Ti-containing ores or concentrate followed by a smaller amount of another neutralizing agent, such as limestone; MgO lime may be used to achieve the required pH in the first leaching liquor. A solid-liquid separation is then conducted from the first liquor-neutralized slurry to provide a solid 135, which is fed to the first leaching stage 120, and a first acid-neutralized leaching liquor 136 which is for an Fe powder reduction stage 140. iii) In the Fe 140 powder reduction stage, the first leaching liquor neutralized with acid 136 is reduced at 45 to 75°C under a nitrogen mantle by adding metallic Fe 141 powder to the converted ferric chloride present in the liquor into ferrous chloride. This step is conducted to achieve Petition 870230008371, dated 01 / 31 / 2023, page 55 / 103 40 / 87 an oxidation-reduction potential (ORP) of the liquor below 100 mV. A solid-liquid separation is then conducted from the first reduced leaching liquor produced to remove any unreacted solid Fe powder 145 and to obtain a reduced liquor 146. The unreacted solid Fe powder 145 can be recycled for use in the reduction stage 140; iv) The reduced liquor 146 is then fed into a vanadium and aluminum removal stage 150, in which vanadium and aluminum are precipitated from the reduced liquor 146 under a nitrogen mantle by increasing the pH of the reduced liquor 146 to ~36 at 50 at 80°C by the addition of limestone or lime as the neutralizing agent 151. A solid-liquid separation is then conducted on the vanadium (V) and aluminum (Al) removed paste produced to separate the precipitated solid 155 and the V / Al removed liquor 156; (v) Recovery of V as vanadium pentoxide (V2O5) from the solid precipitate of V / Al 155 can be done by any suitable recovery process known in the art. In preferred embodiments, V as vanadium pentoxide (V2O5) can be recovered from the solid precipitate of V / Al 155 in a recovery process (not shown) by leaching the precipitate in ammonia solution at a higher temperature to solubilize V as ammonium metavanadate followed by solid-liquid separation of the paste to separate the ammonium metavanadate solution and the undissolved Al-rich solid. The ammonium metavanadate is precipitated by cooling the hot solution and the paste is filtered for solid-liquid separation. The solid ammonium metavanadate is calcined above 250°C to produce the product V2O5. Alternatively, V can be recovered as vanadium pentoxide. Petition 870230008371, dated 01 / 31 / 2023, page 56 / 103 41 / 87 (V2O5) of the solid precipitate of V / Al 155 in an alternative recovery process (not illustrated) by leaching the precipitate in HCl solution at ~50 to 80°C to solubilize V and Al followed by solid-liquid separation to obtain a clear liquor. The prepared V and Al leaching liquor can be treated with an organic solvent Cyanex 372 to extract V in organic solvent leaving Al in the refined liquor. The V-laden organic is removed with HCl solution to obtain V-rich leached liquor and the regenerated organic is recycled to the extraction stage after washing. The V-laden liquor is further treated with ammonia to precipitate V as ammonium metavanadate and the paste is filtered for solid-liquid separation. The ammonium metavanadate precipitate is washed and calcined above 250°C to produce the product V2O5; vi) The removed V / Al liquor 156 is fed to an iron recovery stage 160, in which iron is precipitated from the removed V / Al liquor 156 at a temperature of 70 to 90°C by the addition of limestone or lime as the neutralizing agent 161 in the presence of air 162 (an oxidant for the precipitation reaction) to alter the pH of the solution to ~4 to 7. The precipitated iron removal solid 165 mainly comprises magnetite, goethite, hematite, and akageneite. However, magnetite is the most preferable precipitate of this stage and, as such, the conditions are preferably optimized to substantially precipitate magnetite. A solid-liquid separation is then conducted of the produced iron-removed paste to separate the precipitated solid Fe 165 and the removed Fe liquor 166; vii) The liquor removed with iron 166 is then Petition 870230008371, dated 01 / 31 / 2023, p. 57 / 103 42 / 87 fed into a Mg and Mn removal stage 170, in which magnesium and / or manganese are precipitated from the liquor at a pH ~9 to 10 and a temperature of 60 to 90°C using lime as a neutralizing agent 171 and air 172 as an oxidant typically for the oxidation of Mn(II) to Mn(IV). The precipitated Mg / Mn removal solid 175 will comprise Mg(OH)2 and a mixture of Mn oxide / hydroxide. A solid-liquid separation is then conducted from the removed Mg and Mn paste produced to separate the precipitated solid 175 and the removed Mg / Mn liquor 176, which will be primarily a calcium chloride solution; viii) The Mg / Mn 176 removed liquor, mainly calcium chloride, is fed into an evaporation stage 180 to evaporate a water content to obtain a suitable calcium chloride concentration before the subsequent HCl regeneration stage 190. Evaporation is typically achieved by heating / boiling the Mg / Mn 176 removed liquor through the addition of heat 181; ix) Evaporated calcium chloride liquor 186 is reacted with concentrated sulfuric acid (98% w / w) 191 in the regeneration stage 190 at a stoichiometric ratio of calcium chloride to sulfuric acid, to produce 20 to 22% w / w hydrochloric acid and precipitate calcium as gypsum, hemihydrate, anhydride compounds or a mixture of these compounds. The reaction can be carried out in a temperature range of 30 to 90°C under atmospheric conditions. The reaction between evaporated liquor 186 and concentrated sulfuric acid 191 is preferably carried out in a temperature range of 80 to 85°C aiming to precipitate only the anhydride. A solid-liquid separation is then conducted from the acid paste. Petition 870230008371, dated 01 / 31 / 2023, pp. 58 / 103 43 / 87 regenerated hydrochloric acid produced to separate the precipitated solid 195 and the hydrochloric acid liquor 196, which is recycled back to the first leaching stage 120 for use as the first leaching solution. Stream-2 (Second leaching process stream)

[083] The process for the second leaching process stream 210 (Stream-2) is as follows: i) A second leaching stage 220 of the first leaching solid 125 from the first leaching stage 120 is conducted using a second mixed chloride leaching solution of 20 to 22% w / w HCl and calcium chloride (CaCl2) solution with a total chloride concentration of 400 to 550 g / L at 60 to 80°C, preferably 70 to 80°C, for 4 to 6 h with the addition of Fe powder. The Fe 221 powder is added to provide a reducing atmosphere to obtain greater Ti extraction from the first leaching solid 125, and to aid the dissolution of Ti minerals such as ilmenite, rutile, pseudo-rutile, anatase and the like. The leaching process is followed by solid-liquid separation (part of stage 220) of the resulting second leaching slurry to separate the second leaching solids 225 and the second leaching liquor 226. The second leaching slurry from the second stage / solid 225 exits the process as waste.The second leaching liquor 226 is fed into the subsequent process stages of the second leaching process stream 210.

[084] In some embodiments, Fe 221 powder is added throughout the 4 to 6 hour leaching process. In other embodiments, the second leaching stage 220 is conducted as two separate leaching regimes. In these Petition 870230008371, dated 01 / 31 / 2023, pp. 59 / 103 44 / 87 embodiments, a first leaching regime (second initial leaching) will be carried out for 1 to 2 h in mixed chloride solution without any addition of Fe 221 powder for the dissolution of most of the ilmenite mineral. This is followed by a second leaching regime comprising a continuation of the leaching in mixed chloride solution for 2 to 4 h with the addition of Fe 221 powder to dissolve the remaining unreacted ilmenite and other Ti-containing minerals from the first leaching solid 125, such as rutile, pseudorutile, anatase, etc., under the reducing atmosphere. The Fe 221 powder will also reduce the ferric iron present in the leaching liquor to ferrous iron during the leaching reaction.

[085] In other embodiments, for example, as shown in Figure 4 (described in more detail below), the secondary leaching stage 220C is completed as a two-stage reaction, where the second leaching of the first stage (222C) comprises the dissolution mainly of ilmenite minerals without the addition of Fe powder 221C and the second leaching of the second stage 223C comprises the reaction of the second leaching solid of the first stage with Fe powder to dissolve the remaining unreacted ilmenite minerals and other Ti-containing mineral phases. If necessary, a small additional amount of fresh second leaching solution (mixed chloride solution of 20 to 22% w / w HCl and calcium chloride (CaCl2) solution) can be added to the second leaching 223C in the second stage to stabilize dissolved metals and additional iron from the added Fe powder 221C.A solid-liquid separation is conducted on the second leaching paste produced to separate the second liquor from... Petition 870230008371, dated 01 / 31 / 2023, pages 60 / 103 45 / 87 Ti-rich leaching slurry 227C and the second leaching solids 225C. The second leaching slurry from the second stage / solid 225C exits the process as waste. The second first-stage leaching (222C) preferably includes a solid / liquid separation stage to separate a second first-stage leaching slurry / solid 224C and a second first-stage leaching liquor 226C, with the second first-stage leaching slurry / solid 224C being fed into the second second-stage leaching 223C and the second first-stage leaching liquor 226C being fed into the subsequent oxidation stage 230C to be mixed with the second second-stage leaching liquor 227C, producing a second mixed leaching liquor that is processed as the second Ti-rich leaching liquor 226 (as shown in Figure 1) in the second leaching process stream (as below).

[086] ii) The second Ti-rich leaching liquor 226 is treated with dilute H2O2 231 at oxidation stage 230 to oxidize any Ti (III) content of the liquor to Ti (IV) by controlling the oxidation reduction potential of the liquor within 100 to 200 mV to produce an oxidized Ti (IV) liquor 236; iii) Titanium (as titanium oxide) is then recovered from the oxidized Ti(IV) liquor 236 by adding heated / boiling water 241 to the oxidized Ti(IV) liquor 236 to hydrolyze the Ti(IV) and thus precipitate this content as a solid titanium dioxide (TiO2). The reaction is preferably carried out under an inert gas atmosphere, such as a nitrogen mantle, to prevent iron oxidation. Petition 870230008371, dated 01 / 31 / 2023, pp. 61 / 103 46 / 87 ferrous iron in ferric iron in the liquor and thus prevent unwanted precipitation of ferric iron with TiO2 in the TiO2 washing stage. The resulting Ti(IV) hydrolysis will release HCl into the solution. In some embodiments, this additional HCl can be partially neutralized by the addition of limestone / lime slurry to maximize TiO2 recovery (not illustrated in Figure 1). A solid-liquid separation is then conducted of the produced TiO2 slurry to separate a solid TiO2 245 and a liquor containing ferrous iron 246; iv) As shown in Figure 2, ferrous iron liquor 246 can be subjected to a V / Al removal stage 250 depending on the concentrations of V and Al in the precipitated TiO2 liquor, in which vanadium and aluminum are precipitated under a nitrogen mantle by raising the pH of the ferrous iron liquor 246 to ~3 to 6 at 50 to 80°C, adding limestone or lime as the neutralizing agent 251. A solid-liquid separation is then conducted from the vanadium (V) and aluminum (Al) removed paste produced to separate the precipitated solid 255 and the V / Al removed liquor 256. Vanadium (V) and aluminum (Al) can be recovered from the V / Al precipitation solid by adopting the same procedure as explained for the first leaching liquor; If the concentrations of V and Al in the precipitated TiO2 liquor are higher, then the ferrous iron liquor 246 from this second leaching processing stream 210 can be fed / combined with the V / Al precipitation stage 150 from the first leaching processing stream 110 (as shown in Figures 3 and 4) to simplify / optimize the use of the process of this operation. Petition 870230008371, dated 01 / 31 / 2023, pp. 62 / 103 47 / 87 processing stages, if necessary, as the subsequent downstream steps are identical before the HCl regeneration stage (see below); (v) Ferrous iron liquor 246 is fed to an iron recovery stage 260, in which iron is precipitated from the liquor at a temperature of 70 to 90°C by the addition of limestone or lime as the neutralizing agent 261 in the presence of air 262 (an oxidant for the precipitation reaction) to alter the pH of the solution to ~4 to 7. Again, the precipitated iron removal solid 265 mainly comprises magnetite, goethite, hematite, and akageneite. However, magnetite is the most preferable precipitate from this stage. The conditions are preferably optimized to substantially precipitate magnetite. A solid-liquid separation is then conducted from the iron-removed paste produced to separate the precipitated solid Fe 265 and the iron-removed liquor 266, which is mainly the calcium chloride solution; vi) Calcium chloride solution 266 is fed into an evaporation stage 270 to evaporate a portion of the water to obtain a suitable calcium chloride concentration before the subsequent HCl regeneration stage 290. Evaporation is typically achieved by heating / boiling the calcium chloride solution 266 through the addition of heat 271. In this evaporation stage 270, the water has partially evaporated to produce concentrated calcium chloride solution 276 with a calcium chloride concentration required for the second generation of leachate; vii) Where the liquor includes a magnesium and / or manganese content, the second leaching process stream 210 Petition 870230008371, dated 01 / 31 / 2023, pages 63 / 103 48 / 87 may include a Mg and Mn removal stage 280. Here, a content is bled from the process line to a bleed line 279 (Figures 1 and 2), or a dedicated stage is used (Figures 3 and 4). In each case, the liquor is fed into a Mg and Mn removal stage 280, in which magnesium and / or manganese is precipitated from the liquor at a pH ~9 to 10 and a temperature of 60 to 90°C using lime as a neutralizing agent 281 and air 282 as an oxidant typically for the oxidation of Mn(II) to Mn(IV). The precipitated Mg / Mn removal solid 285 will comprise Mg(OH)2 and a mixture of Mn oxide / hydroxide. A solid-liquid separation is then conducted on the removed Mg and Mn paste produced to separate the precipitated solid 285 and the removed Mg / Mn liquor 286, which will be primarily a calcium chloride solution; viii) Concentrated calcium chloride solution 276 is reacted with concentrated sulfuric acid (98% w / w) 291 in the regeneration stage 290 at a necessary stoichiometric ratio of calcium chloride in the liquor to sulfuric acid to regenerate the second leach (an equivalent of 20 to 22% w / w hydrochloric acid in the liquor, leaving the remaining calcium chloride in solution) and simultaneously precipitating gypsum compounds, hemihydrate or anhydride, or a mixture of these compounds. The reaction can be carried out in a temperature range of 30 to 90°C. The reaction can be carried out in a temperature range of 30 to 90°C under atmospheric conditions. The reaction between concentrated calcium chloride solution 276 and concentrated sulfuric acid 291 is preferably carried out in a temperature range of 80 to 85°C aiming to precipitate only the anhydride. A separation of Petition 870230008371, dated 01 / 31 / 2023, pp. 64 / 103 49 / 87 solid-liquid is then driven from the regenerated mixed chloride paste produced to separate the precipitated solid and the second regenerated leach solution 296. The second regenerated leach solution 296 is recycled back to the second leaching stage 220.

[087] It should be appreciated that the neutralizing agents 151, 161, 251, 261 for: i) Al / V removal step 150, 250; and ii) Fe removal steps 160, 260 in Stream-1 110 and Stream-2 210 of process 100, may be limestone or lime (as discussed), and / or in other forms of MgO. Among these neutralizing agents, limestone is the preferred neutralizing agent 151, 161, 251, 261, as it is a low-cost reagent.

[088] Figure 1 exemplifies the use of limestone or lime as a neutralizing agent 151, 161, 251, 261. However, it should be appreciated that when MgO is added for neutralization for these steps 150, 250, 160, 260, it will form MgCl2 in the relevant liquor. Therefore, where MgO is used in process 100, the process liquors will comprise a solution containing MgCl2 for Stream-1 100 and a solution containing CaCl2 and MgCl2 mixed for Stream-2 210 (where CaCl2 is used as the additional chloride in the second leach, it may be a solution containing MgCl2 for Stream-2 210, where MgCl2 is used as the additional chloride in the second leach). Any Mg content will be removed using the Mn / Mg removal steps described in steps 170 and 280 of process 100. However, in these steps, MgO would need to be regenerated from the Mg removal steps 170 and 280, and the regenerated solid recycled back to the neutralization steps 150, 250, 160, and 260. Petition 870230008371, dated 01 / 31 / 2023, pages 65 / 103 50 / 87

[089] The following process steps are required after the Fe removal step, when MgO is used as a neutralizing agent: If Mn is present in the liquor obtained after the Fe removal step, then the Mn removal and Mg removal steps 170, 280 will be carried out separately using lime as the neutralizing agent; a) First, a Mn removal step will be performed using the liquor removed with Fe 166, 276 in the presence of an oxidant (e.g., air, oxygen, H2O2) at a pH below 9, adding lime to precipitate Mn as oxide / hydroxide or as a mixture. Solid-liquid separation will be performed to obtain a Mn-removed liquor and a Mn-rich precipitate; b) Mg removal can then be carried out after Mn removal using Mn-removed liquor at pH 9 to 10 by adding lime to precipitate Mg as Mg(OH)2 and the liquor will mainly contain CaCl2 (for HCl regeneration). The Mg(OH)2 obtained after solid-liquid separation will be subjected to calcination at ~300 to 400°C to regenerate MgO for recycling; c) In the embodiments where Mn is not present in the liquor obtained after the Fe removal step, only a single Mg removal step will be necessary as explained above.

[090] Where MgCl2 is used as the additional chloride in the second leach, the leaching of Ti in the second leaching stage 220 will be carried out using a second leach comprising a mixture of HCl solution and MgCl2. Although not illustrated, it should be appreciated that the liquor after the precipitation of TiO2 can go to Fe removal using MgO Petition 870230008371, dated 01 / 31 / 2023, pp. 66 / 103 51 / 87 to produce magnetite (instead of high-temperature FeCl3 / FeCl2 hydrolysis to produce hematite) and the necessary MgCl2 solution. As indicated above, a required amount of Mg(OH)2 can be precipitated using lime from the MgCl2 solution to obtain a CaCl2 + MgCl2 solution, where the CaCl2 concentration must be equivalent to or greater than 20-22% w / w HCl for regeneration using 98% H2SO4. In this case, MgO and the HCl + MgCl2 solution are also regenerated.

[091] As shown in Figures 2 and 3, common stages for the first leaching process stream 110 and the second leaching process stream 210, such as V / Al removal 350, Fe removal 360 and Mg / Mn removal 370, can be combined to run in a common process stream 310 to reduce capital investment and also operating cost. Here, the liquors from the first leaching process stream 110 and the second leaching process stream 210 are combined before V / Al removal 350 and are separated into separate process streams before evaporation stages 180 and 270. However, it should be appreciated that evaporation stage 180 after Mg / Mn removal may not need to generate 20 to 22% w / w HCl for the first leaching process stream 110, as the CaCl2 concentration may be high enough due to the mixing of the process liquors before the V / Al precipitation step 250.Therefore, only a single evaporation stage may be necessary in some applications.

[092] As indicated above, in some embodiments, the second leaching stage 220 can be modified to Petition 870230008371, dated 01 / 31 / 2023, pages 67 / 103 52 / 87 reduce the addition of Fe 221 powder and increase overall Ti extraction by performing a second two-stage leaching. As illustrated in Figure 4, the second leaching stage 220C can comprise two leaching stages: i) second leaching stage (SL) 222C; and ii) second reducing leaching (RSL) 223C. SL 222C is performed without a reductant, and RSL 223C is performed with the addition of Fe powder. The second two-stage leaching stage 220C can allow the elimination / minimization of the need for H2O2 for Ti(III) oxidation, since the leaching liquor SL 226C from SL 222C containing Fe(III) will oxidize the Ti(III) present in leaching liquor RSL 227C.However, the ratio of SL 226C leaching liquor to RSL 227C leaching liquor must be adjusted appropriately so that only the oxidation of Ti(III) occurs in the RSL 227C leaching liquor; otherwise, the Ti(IV) present in the SL 226C leaching liquor may be reduced if excess RSL 227C leaching liquor is added.

[093] Each of the described stages can be carried out in process vessels suitable for leaching, precipitation, boiling, mixing, and similar process steps. As noted previously, no specialized construction material is required for the reactor design criteria in this process. Standard fiberglass and / or high-density polyethylene (HDPE) and / or polypropylene (PP) tanks can be used to meet the reactor / equipment requirements. Compared to the previous pyrohydrolysis technique or high-temperature hydrolysis technique, the leachate regeneration in the present invention is a simpler process where the requirement for Petition 870230008371, dated 01 / 31 / 2023, pages 68 / 103 53 / 87 energy is low and the construction material is not critical (i.e., it does not require materials resistant to high temperature and corrosion).

[094] It should be appreciated that solid / liquid separation for all stages can be operated using any suitable method and process equipment. Techniques for such separation are known, for example, using a pressure or vacuum filter, countercurrent decantation, thickener or centrifuge. In particular embodiments, solid / liquid separation can be operated using a thickening operation. Washing steps will only be applicable to solids exiting the circuit, such as: i) final leaching solid from the second leaching; ii) TiO2 precipitate; iii) V / Al precipitate; iv) Fe precipitate; v) Mg / Mn removal solid; and vi) gypsum solids. It would not be essential to wash the intermediate solid that is moved from one stage to another within the process, as the respective process stages must be able to accommodate any entrained liquor coming with the intermediate solids.

[095] The product of this process is a high-quality titanium dioxide product, along with one or more additional value metals selected from vanadium, aluminum, iron, magnesium or manganese. EXAMPLES

[096] Aspects of the two-stream process of the present invention are illustrated by the following examples. EXAMPLE 1 - Recovery of titanium dioxide from ilmenite-containing Ti ore concentrate 1. Experimental Process Petition 870230008371, dated 01 / 31 / 2023, pp. 69 / 103 54 / 87

[097] An experimental process flowchart, as shown in Figure 1, was developed to test a titanium and other valuable metal recovery process that can operate at low HCl concentration (~20 to 22% w / w HCl) for a Ti ore (see composition below) originating from Western Australia that can also regenerate HCl at low temperature (< 100°C) under atmospheric conditions. As described above, there are two main process streams for the proposed flowchart, where Stream-1 was studied in a ~20 to 22% w / w HCl system and Stream-2 was studied in a mixed HCl + CaCl2 system with ~20 to 22% w / w HCl and CaCl2 with a CaCl2 concentration of ~300 g / L. The different stages traversed in the investigation for both streams were: • Process stream-1: primary leaching, neutralization of the leaching liquor, reduction of the neutralized liquor, removal of V / Al, removal of Fe, removal of Mg / Mn, evaporation of the Mg / Mn-removed liquor (to concentrate CaCl2 in the liquor for HCl regeneration) and regeneration with hydrochloric acid; • Process Stream-2: Secondary leaching of the primary leaching residue from Stream-1, recovery of TiO2, removal of Fe, removal of Mg / Mn, evaporation of the liquor removed from Mg / Mn (to concentrate CaCl2 in the liquor) and regeneration of hydrochloric acid. 2. Method and Materials 2.1 Materials

[098] A ~10 kg Ti ore concentrate from Western Australia and ~1 kg Fe powder (Fe 120 sand) were used in this investigation. The concentrate was Petition 870230008371, dated 01 / 31 / 2023, pp. 70 / 103 55 / 87 was fully homogenized and a subsample was collected for analysis. The various chemicals, such as HCl, H2SO4, FeCl3, CaCO3, and Ca(OH)2 used in this investigation were of laboratory reagent grade. 2.2 Experimental procedure 2.2.1 Pre-leaching test work with diluted HCl, H2SO4 and FeCl3

[099] The pre-leaching test work was carried out in a 0.5 L glass reactor using 5% w / w HCl, 5% w / w H2SO4 and ~150 g / L FeCl3 solutions at ~65°C with ~20% w / w pulp density for 2 h. The concentrate and the prepared solution of HCl, H2SO4, FeCl3 were placed in the reactor and heated in a water bath at 65°C for 2 h. The final paste was filtered, and the liquor was analyzed for the desired elements by ICP-OES. 2.2.2 Process stream-1 2.2.2.1 Primary leaching

[100] Primary leaching tests were carried out in 2 L and 5 L glass reactors using 17% to 21% w / w HCl at 95 to 97°C with a pulp density of 20% w / w for 1 to 4 h. The reactor was equipped with a glass lid connected to a condenser. For the two initial tests, a required amount of HCl solution was taken from a 2 L reactor and the concentrate was added to the reactor at 50 to 60°C. Once the reaction temperature was reached (~95°C), a sample was collected, and the reaction continued for 4 hours with sampling every hour. The samples were filtered, and the solids were initially washed with ~15% HCl solution, followed by repulping / washing with deionized water (DI). At the end of the reaction, the reactor slurry was Petition 870230008371, dated 01 / 31 / 2023, pp. 71 / 103 56 / 87 filtered; the solid was thoroughly washed and dried at 60°C in an oven.

[101] Three volumetric leaching tests were performed in a 5 L reactor for 2 h. A required amount of concentrated material and HCl solution was placed in the reactor and heated to the test temperature. At the end of the test, a sample was collected and filtered through a pressure filter. The solid was washed similarly as described for the initial tests. The volumetric paste was filtered through a pressure filter and the liquor was stored in an airtight bottle. The wet cake was repulped with ~2 times the cake volume of ~15% HCl solution, followed by a second repulping of the first washing cake with ~2 times DI water (deionized water). A representative wet cake sample was collected from the second washed cake for moisture determination and chemical analyses. The washed wet cake was stored in an airtight bag for reductive leaching test work. The solid, final liquor, and wash liquors were analyzed for Fe, V, Ti, Al, Mn, Ca, Mg, and Si.Free acid was analyzed in the collected samples and in the final liquors. The final liquors and the second washed cakes from the three volumetric leaching tests were homogenized separately and stored in hermetically sealed containers. The homogenized liquor was used for further processing, and the cake was used for the stream-2 leaching test work.

[102] A primary leaching test was also carried out in a 2 L reactor using HCl regenerated from Stream-1 of the process following the same conditions and procedure as the bulk leaching test. The test was conducted for 2 h without collecting any samples. Petition 870230008371, dated 01 / 31 / 2023, pp. 72 / 103 57 / 87 2.2.2.2 Neutralization of primary leaching liquor

[103] Free acid analyses reported a very high acid concentration (~140 g / L) in the homogenized primary leaching liquor. Most of the free acid in the leaching liquor was neutralized by adding concentrated Ti material in a 5 L reactor. The final paste was filtered, and the liquor was stored for later processing.

[104] The concentrated neutralized Ti liquor was subsequently treated with limestone to neutralize the remaining free acid to obtain a free acid in the liquor < 5 g / L. 2.2.2.3 Reduction of iron from neutralized leaching liquor

[105] Reduction tests were performed in 0.5 L and 5 L glass reactors (equipped with pH and ORP probes) at 70°C using leaching liquor neutralized with concentrate / limestone. A calculated amount of Fe 120 sand was slowly added to the reactor containing neutralized concentrate / limestone liquor for Fe(III) reduction. Tests were performed under a nitrogen mantle during the addition of Fe sand. Online pH and ORP (oxidation-reduction potential) were continuously recorded until the liquor ORP was considered negative and relatively stable. The slurry was filtered in a filter press and the solid was repulped / washed with water and dried in an oven. The final liquor was stored in an airtight bottle under a nitrogen mantle for further testing. Both the solid and the liquor were subjected to analysis. 2.2.2.4 Removal of aluminum and vanadium from reduced liquor

[106] Al / V removal tests were carried out in 0.5 L and 5 L glass reactors (equipped with pH probes) Petition 870230008371, dated 01 / 31 / 2023, pp. 73-103 (58 / 87 and ORP) at 70°C, raising the pH of the reduced liquor with limestone. The limestone paste was slowly added to the reactor at 70°C, measuring the pH and ORP online. Tests were performed under a nitrogen mantle to prevent ferrous oxidation. At the end of the test, the paste was filtered in a filter press, and the solid was repulped / washed with water and dried in an oven. The final liquor was stored in an airtight bottle under a nitrogen mantle for further testing. Both the solid and the liquor were subjected to analysis. 2.2.2.5 Removal of iron from Al / V removed liquor

[107] Iron removal tests were performed in a 2 L glass reactor equipped with pH and ORP probes, thermometer, air purge tube, and condenser. The test solution was heated to a defined temperature (80°C) under a nitrogen mantle to prevent Fe(II) oxidation. Initially, lime or limestone paste was added to raise the reactor pH to a target precipitation pH of ~4.2 to 5.0, followed by air purging initiated at a flow rate of ~2.0 to 5.0 L / min. The reactor pH was maintained by continuously adding limestone paste. A sample was collected before starting air addition, followed by samples collected at regular intervals. The collected samples were filtered immediately, the wet cake was washed abundantly with deionized water, and dried in an oven at ~60°C. The iron concentration in the filtrate was determined by analyzing the iron concentration using the standard dichromate method.Based on ferrous analyses, the retention time for the iron removal test was determined. Typically, the tests were performed over a period of 3.5–5.0 h. Petition 870230008371, dated 01 / 31 / 2023, pp. 74 / 103 59 / 87

[108] At the end of the test, the paste was filtered using a pressure filter. The cake was washed with deionized water by repulping, and the washed solid was dried in the oven. The solids and liquors were subjected to chemical analyses. 2.2.2.6 Removal of magnesium and manganese from liquor removed with Fe

[109] Magnesium and manganese removal was carried out at 60°C in a 5 L reactor equipped with pH and ORP probes using liquor removed with Fe. Dry lime was slowly added to the reactor at 60°C to increase the pH ~9 of the liquor followed by a calculated amount of 7.5% w / w H2O2 added for Mn oxidation. The final paste was filtered and the solid was washed by repulping and then dried at 60°C. The solid and liquor were subjected to analyses. 2.2.2.7 Regeneration of hydrochloric acid from liquor removed from Mg / Mn

[110] Before the HCl regeneration test work, the Mg / Mn removed liquor was evaporated in a 5 L beaker using a hot plate to achieve a required Ca concentration in the liquor, so that > ​​20% w / w HCl could be produced during the HCl regeneration reaction.

[111] The HCl regeneration test work was carried out in 0.5 L and 1 L reactors at 80 to 85°C, adding a calculated amount of 98% w / w H2SO4 using evaporated liquor. Initially, the solution was heated to ~60 to 70°C and the addition of H2SO4 was started. The acid was added slowly / drip, and the temperature increase of the reactor paste was recorded. Once the reactor paste reached ~80 to 85°C, the acid addition was controlled to maintain the reactor temperature. At the end of the reaction, the paste Petition 870230008371, dated 01 / 31 / 2023, pp. 75-103 60 / 87 final was filtered in a filter press and the cake was repulped / washed twice with approximately one volume of water-saturated gypsum cake. The solid was dried at ~45°C. The final liquor was stored for recycled leaching of the concentrated feed material. The acid concentration in the final liquor was determined using standard titrimetric analyses. The solid, final, and washing liquors were subjected to elemental analyses. 2.2.3 Process stream-2 2.2.3.1 Secondary leaching of primary leaching residue

[112] Secondary leaching tests were carried out in 2 L and 5 L glass reactors using primary leaching residue in HCl-CaCl2 mixed solution at 75 to 80°C for 4 to 6 h in the absence and presence of Fe 120 sand reducing agent. A required amount of wet primary leaching cake and HCl-CaCl2 solution (with the desired concentration of HCl and CaCl2) was placed in a reactor to obtain a pulp density of ~4.9 to 8.8% w / v. The reactor was fitted with a condenser, thermometer and ORP probe and placed in a hot water bath. The reaction continued for 1 to 3 h at the test temperature, after which ~1.3 to 2 g of Fe 120 sand were added manually (when appropriate) at regular intervals of ~5 to 10 minutes until the end of the reaction. The online ORP of the reaction was recorded during leaching with the addition of Fe sand. Samples were collected at 1-hour intervals and immediately filtered in a filter press.The solid was initially repulped / washed with 15% w / w HCl followed by repulping / washing with DI water. The final paste was processed similarly to the sample. Petition 870230008371, dated 01 / 31 / 2023, pp. 76 / 103 Sample 61 / 87 was collected. The (filtered) liquor was immediately diluted for analysis, as crystallization occurred in the leaching liquor after storage at room temperature.

[113] Two bulk secondary leaching tests were carried out without sampling in a 5 L reactor with the addition of Fe sand to generate leaching liquor for further treatment. At the end of the reaction, the slurry was filtered in a filter press and the liquor was stored in a hermetically sealed bottle at ~60°C to prevent iron crystallization. The wet cake was initially repulped / washed with ~2 times the cake volume of 15% w / w HCl, followed by DI water to generate washing data. The second washed cake was dried at 60°C. The final diluted liquor, the washing liquors, and the solids were subjected to analyses. Liquor leachers from both tests were used for the TiO2 precipitation test work. 2.2.3.2 TiO2 Precipitation

[114] Titanium dioxide precipitation tests were performed in 0.5 L and 5 L reactors at 90 to 95°C by hydrolysis of the Ti ion from the secondary leaching solution in hot water. Initially, the secondary leaching solution was oxidized at room temperature with dilute H2O2 to obtain an ORP of ~150 to 200 mV. A required amount of DI water was heated to the test temperature in a reactor equipped with a thermometer and condenser. The oxidized solution was added slowly until the water-to-liquor ratio became 1:1, followed by stirring of the paste to prevent possible agglomeration of TiO2 particles. The test was performed under a nitrogen mantle to minimize Fe(II) oxidation. At the end of the test, the paste was filtered through a Petition 870230008371, dated 01 / 31 / 2023, pp. 77 / 103 62 / 87 pressure filter and the liquor was stored for further processing. The solid was initially washed with 10-15% HCl followed by DI water. The solid was dried at 60°C overnight. Solid and liquor samples were submitted for analysis. The TiO2 precipitation test liquors were combined to generate a bulk liquor for further processing. 2.2.3.3 Acid neutralization and removal of iron from precipitated TiO2 liquor

[115] The liquor removed from TiO2 reported high free acid analysis (~70 g / L) which was neutralized by the addition of limestone. Acid-neutralized liquor was used for Fe removal. Fe removal tests were carried out in a 5 L reactor using the neutralized liquor following the same procedure as explained in Section 2.2.2.5. The iron removal test liquors were homogenized for further downstream processing. 2.2.3.4 Removal of magnesium / manganese from liquor removed with Fe

[116] Initially, the liquor removed with Fe was partially evaporated (~34% by volume) by heating the solution on a hot plate. The partially evaporated liquor was used for Mg / Mn removal following the same procedure as described in Section 2.2.2.6. 2.2.3.5 Regeneration of hydrochloric acid from liquor removed from Mg / Mn

[117] The final liquor removed from Mg / Mn was further evaporated to achieve a required Ca concentration in the liquor, so that ~20% w / w HCl could be produced during the HCl regeneration reaction. HCl tests were carried out in Petition 870230008371, dated 01 / 31 / 2023, pp. 78 / 103 63 / 87 a 2 L glass reactor using the same procedure as described in Section 2.2.2.7. 3. Results 3.1 Chemical and mineralogical analyses

[118] Analyses of Ti concentrate originating from Western Australia are presented in Table 1. Elemental analyses were ~34% Fe, 0.34% V, 23.6% Ti, 2.2% Al, 0.8% Mg, 3.7% Si and < 0.2% analyses of Ca, Cr, Cd, Cu, Na, K and Zn. The mineralogy of the concentrate reported the phases of ilmenite, hematite, goethite and quartz, along with a reasonable amount of clinochlore and kaolinite minerals. Table 1. Analyses of the Ti concentrate originating from Western Australia Analysis of Ti concentrate (%) Fe V Ti Al Mn Ca Mg 33.84 0.34 23.59 2.19 0.19 0.21 0.75 Si Cd Cr Cu K Na Zn 3.73 < 0.01 0.005 0.020 0.109 0.14 0.036 3.2 Pre-leaching test results

[119] The aim of pre-leaching was to examine whether it was possible to remove unwanted impurities before the primary leaching test. The unwanted impurities are mainly monovalent cations, such as Na and K, as these are the unrecoverable chloride-consuming elements. Three pre-leaching tests were performed using solutions of 5% w / w HCl, 5% w / w H2SO4 and ~150 g / L FeCl3 at 65°C with ~20% w / w pulp density for 2 h. The analyses of the leaching liquor and the percentage of dissolved metals are presented in Table 2 and Table 3. Petition 870230008371, dated 01 / 31 / 2023, pp. 79 / 103 64 / 87 respectively. Table 2. Analysis of the leaching liquor from pre-leaching tests using 5% w / w HCl, 5% w / w H2SO4 and 150 g / L FeCl3 Pre-leaching Liquor pH Analysis mg / L Fe(t) V Ti Al Mn Ca Mg Na K Cu Zn Final pre-leaching of HCl 0.23 39 40 40 27 827 40 42 585 25 13 8 12 Final pre-leaching of H2SO4 0.63 23 83 23 13 819 35 42 621 24 10 6 19 Feed of pre-leaching of FeCl3 0.69 45 551 <1 <1 14 87 2 <1 <1 <1 9 5 Final pre-leaching of FeCl3 0.70 45 986 <1 <1 76 121 39 48 24 7 12 8 Table 3. Dissolution of metals for pre-leaching tests using HCl, H2SO4 and FeCl3 solutions. Test % of Metal Dissolution Fe (t) V Ti Al Mn Ca Mg Na K Cu Zn Pre-liquidation of HCl 4.5 4.6 14.6 8.1 7.7 30.2 7.0 4.8 15.1 13.1 Pre-liquidation of H2SO4 2.7 2.6 14.4 7.1 7.6 31.8 6.5 3.4 11.4 12.6 Pre-liquidation of FeCl3 3.8 0.1 1.2 8.9 7.8 2.8 7.2 2.6 7.3 4.1

[120] The liquor analysis data indicated the dissolution of some Fe, Al, Mn, Ca, Mg, Na, K, Cu, Zn in these tests, where the dissolution of Al and Mg for FeCl3 leaching was very low compared to H2SO4 / HCl leaching. Approximately 23 to 40 mg / L of dissolution V was reported for HCl and H2SO4 leaching, which was undesirable for pre-leaching tests. However, no dissolution of V occurred in the FeCl3 system. Due to the low dissolution of Na and K, pre-leaching tests were not essential for the Ti concentrate to be used for the flowchart development study. The analyses of Na and K in the concentrate were also very low (~0.1%). Petition 870230008371, dated 01 / 31 / 2023, pages 80 / 103 65 / 87 therefore, no other pre-leaching test was performed, and the concentrate was used directly for the primary leaching test. 3.3 Process stream-1 3.3.1 Primary leaching

[121] The objective of this primary leaching was to dissolve as much of the impurities and V as possible, leaving the ilmenite intact in the leaching residue for secondary leaching. Initially, two primary leaching tests were carried out at ~97°C with 20% w / w pulp density for 4 h using ~21% w / w and ~17.5% w / w HCl concentrations. Leaching extraction data are shown in Figure 5 for Fe and Mg and in Figure 6 for V and Al. Fe and Mg extractions were similar at both 17.5% and 21% w / w HCl concentrations. V and Al extraction was slightly higher at 21% w / w HCl compared to 17.5% w / w HCl. Figures 5 and 6 show most Fe, Mg, V, and Al extractions within 1 to 2 hours of leaching; this indicates that a leaching time of 2 hours should be sufficient for primary leaching under the conditions used.It was observed that titanium dissolution gradually increased during leaching at both 17.5% and 21% w / w HCl concentrations (Figure 7). The rate of increase was relatively higher at 21% w / w HCl compared to 17.5% w / w HCl. After 2 h of leaching, Ti dissolution of ~0.5 g / L and ~1.0 g / L occurred for 17.5% and 21% w / w HCl concentrations, respectively. Figure 7 clarifies that some Ti dissolution (at least 0.5 g / L of Ti) will occur during primary leaching within 17.5% to 21% w / w HCl concentrations, and minimizing the concentration will be difficult. Petition 870230008371, dated 01 / 31 / 2023, pp. 81 / 103 66 / 87 of Ti below 0.5 g / L, unless the acid concentration is reduced further. However, the reduced acid concentration will also reduce V extraction. Therefore, considering the higher V extraction in primary leaching, a 21% w / w HCl concentration was chosen for the additional primary leaching test work to generate the bulk leaching liquors.

[122] Three primary bulk leaching tests (PL3, PL-4 and PL-5) were carried out in 21% w / w HCl for 2 h, keeping other conditions constant. The leaching test results were considered reproducible. The leaching conditions of 21% w / w HCl, 97°C, 20% w / w pulp density and for 1 to 2 h resulted in the dissolution of 48% Fe, 69% V, ~51% Al, 98% Mg, ~16% Mn, 1.8% Ti and 0.4% Si. The mineralogy of the leached solid reported the ilmenite, quartz and clinochlore phases, along with the minor appearance of the rutile phase. Leach liquor analyses showed 41.5 g / L of Fe, 0.64 g / L of V, 0.9 g / L of Ti, 3 g / L of Al, 2.1 g / L of Mg, and < 0.1 g / L of Mn, Ca, and Si, along with a free acid concentration of 140 g / L. Leach cake analyses reported 24–25% Fe, 27% Ti, ~1.5% Al, 4.5% Si, 0.15% V, 0.23% Mn, and 0.02% Mg in the solid.

[123] The leaching liquor was treated in Stream-1 for downstream processing and the leaching cake was used for secondary leaching in Process Stream-2. 3.3.2 Neutralization of primary leaching liquor

[124] The high free acid content of the primary leaching liquor was neutralized with Ti concentrate and a final free acid concentration of ~41 g / L was achieved. Petition 870230008371, dated 01 / 31 / 2023, pp. 82-103 67 / 87 The concentration of metals in the neutralized liquor increased, giving an analysis of ~73 g / L of Fe, 1.26 g / L of V, 0.4 g / L of Ti, 6 g / L of Al, 4.1 g / L of Mg, and < 0.2 g / L of Ca, Mg, and Si in the liquor.

[125] The concentrated neutralized Ti liquor was subsequently neutralized with limestone to reduce the free acidity to < 5 g / L before the Fe (III) reduction stage. 3.3.3 Reduction of iron(III) from neutralized leaching liquor

[126] The neutralized liquor was treated for reduction of Fe(III) to Fe(II) with the addition of Fe powder (Fe sand 120). Reduction tests were carried out at 70 °C adding Fe powder (Fe sand 120) above the stoichiometric requirement under a nitrogen mantle to prevent air oxidation of Fe(II). For a typical test with 1.17 times the stoichiometric addition of Fe sand, the pH and ORP profiles are given in Figure 8, which shows an increase in pH (to 1.47) and a decrease in ORP (to -345 mV) over time. The pH and ORP of the final reduced liquor were ~1.9 and -400 mV, respectively, at room temperature. The oxidation-reduction potential (ORP) of the liquor / paste decreased over time to a negative ORP and simultaneously the pH increased and remained below 2. There was a loss of ~5% of V in the solid due to the increase in pH. However, this loss of V is recoverable by dissolving the precipitate in HCl solution. The final concentration of Fe as Fe(II) in the reduced liquor was ~110 g / L.

[127] The reduced liquor was treated to remove V and Al at 70°C under a nitrogen mantle to precipitate V and Al together. Petition 870230008371, dated 01 / 31 / 2023, pp. 83 / 103 68 / 87 increasing the pH with the addition of limestone. 3.3.4 Removal of vanadium and aluminum from reduced liquor

[128] The removal of V and Al from the reduced liquor containing ~111 g / L of Fe, 1.19 g / L of V and 6.1 g / L of Al was carried out at 70°C raising the pH of the liquor to ~4.0 under a nitrogen mantle with the addition of limestone and / or lime to precipitate V / Al as hydroxides.

[129] Initially, two V / Al precipitation tests (V / Al PN-1 and V / Al PN-2) were performed by adding limestone and lime with / without the addition of H2O2 to understand the precipitation behavior of V and Al. H2O2 was added to increase the ORP of the reduced liquor to ~200 mV, since the initial ORP of the reduced liquor was about -300 mV. Partial oxidation with H2O2 was performed before the addition of limestone. In the two initial tests, the target pH was adjusted to ~4.5. However, the addition of limestone alone failed to reach the target pH, possibly due to partial oxidation / precipitation of Fe(II). Therefore, an attempt was made to increase the pH by adding a small amount of lime paste after the calculated amount of limestone addition. However, the pH of the reaction paste remained ~4 or less, even after the addition of lime. Analysis of the sample collected after the calculated amount of limestone addition yielded precipitation of V and Al > 96%.This indicated that the addition of limestone was effective for the precipitation of V / Al and the addition of lime was not necessary.

[130] Based on the two initial tests, a third test (V / Al PN-3) was carried out by adding only limestone without any H2O2, where more than 99% precipitation of V and Al occurred, resulting in final liquor analyses of V and Al < 10 Petition 870230008371, dated 01 / 31 / 2023, pp. 84 / 103 69 / 87 mg / L and 50 mg / L, respectively, of a feed liquor with 1.19 g / L of V and 6.1 g / L of Al along with ~111 g / L of Fe, 0.45 g / L of Mn, 18 g / L of Ca and 4 g / L of Mg. A typical V / Al precipitation solid test analysis reported 2.6% V, 15.7% Al, 0.6% Fe, 0.01% Ti, 6.9% Ca, < 0.001% Mn / Mg and 0.3% Si. 3.3.5 Removal of iron from liquor removed with V / Al

[131] Fe removal was performed using V / Al removed liquor (containing ~99 g / L of Fe) at 80°C, adding limestone (15 to 30% w / w of pulp density) as the neutralizing agent and air as an oxidant at a flow rate of ~5 L / min. Feed liquor analyses are provided in Table 5 and Fe precipitate analyses are provided in Table 6. The test took 3.5 h for complete Fe removal. Table 5. Representative feed and final liquor analyses for Fe removal tests. Analysis of liquor, mg / L Fe V Ti Al Mn Ca Mg Si Feed liquid 98731 0.3 0.1 41 378 33654 3793 0.5 Final liquid 0.23 184 53249 2013 Table 6. Representative analyses of precipitated solids for the Fe removal test. Fe precipitate analyses, % Fe V Ti Al Mn Ca Mg Si Final solid 53.5 0.001 0.000 0.030 0.045 7.4 0.004 0.006

[132] Effectively complete removal of Fe was achieved by precipitating Fe as magnetite, leaving < 1 mg / L of Fe in the final liquor. Analyses of the liquor removed with Fe reported < 1 mg / L of Fe, 184 mg / L of Mn, ~53.2 g / L of Ca and ~2 g / L of Mg. Petition 870230008371, dated 01 / 31 / 2023, pages 85 / 103 70 / 87 3.3.6 Removal of magnesium and manganese from liquor removed with Fe

[133] Mg and Mn removal was performed using liquor removed with Fe at 60°C, raising the pH of the liquor to ~9 with lime to precipitate Mg as Mg(OH)2 followed by oxidation of Mn(II) to Mn(III) / Mn(IV) with 7.5% H2O2 to precipitate Mn as Mn oxide. Feed and final liquor analyses of the Mg / Mn removal test are provided in Table 7. Table 7. Feed and final liquor analyses from the Mg / Mn removal test at 60°C with lime and H2O2 addition. Analysis of liquor, mg / L Mn Ca Mg Feed liquid 202 58697 2397 Final liquid 0.01 61462 1.36

[134] Complete removal of Mg and Mn was achieved by providing a Mg / Mn oxide / hydroxide cake analysis of 0.02% Fe, 1.94% Mn, 22.5% Mg and 14.5% Ca. 3.3.7 Evaporation of the removed liquor with Mg / Mn

[135] The Mg / Mn depleted liquor was evaporated to obtain ~130 g / L of Ca in the final liquor for the HCl regeneration test work. 3.3.8 Regeneration of HCl from evaporated liquor removed with Mg / Mn

[136] HCl regeneration was carried out using the liquor evaporated at 80 to 85°C with a stoichiometric requirement of 92 to 97% addition of H2SO4, where 97% stoichiometric addition produced 296 g / L of HCl (26.6% w / w HCl), while 92% stoichiometric addition produced 260 to 270 g / L of HCl concentration (~23 to 24% w / w HCl). The precipitate generated during the HCl regeneration reaction Petition 870230008371, dated 01 / 31 / 2023, pp. 86 / 103 71 / 87 was primarily gypsum (CaSO4.2H2O) with some anhydride (CaSO4) and a smaller amount of basanite (CaSO4.05H2O as hemihydrate). Washing the cake with ~1.2 times the amount of gypsum-saturated water yielded ~114-126 g / L of HCl (~11 to 12% w / w) and ~50 g / L of HCl (~4.8% w / w) in the first and second washes, respectively. A third wash may be necessary for most of the remaining HCl, depending on the chloride loss in the second cake wash.

[137] The regenerated HCl was recycled for primary leaching of Ti concentrate under primary leaching conditions, where the leaching extraction was ~44% Fe, 68% V, 55% Al, 99% Mg and 14% Mn, as shown in Table 8. These leaching data were very similar to the metal extraction data obtained in primary leaching with 21% w / w fresh HCl. Table 8. Metal extraction for primary leaching test with recycling of regenerated HCl (21% w / w) at 96-98°C with 20% pulp density for 2 h compared with fresh HCl (21% w / w) at 96-98°C with 20% pulp density for 2 h % Extraction Fe V Ti Al Mn Ca Mg Si Recycled HCl 44.3 67.8 0.7 55.1 14.2 99.5 0.9 Fresh HCl 47.2 68.8 1.5 48.3 16.0 96.6 0.5

[138] The results of tests of all stages of Process Stream-1 confirmed that Stream-1 of the proposed flowchart illustrated in Figure 1 is metallurgically feasible. 3.4 Process Stream-2 3.4.1 Secondary leaching of primary leaching residue Petition 870230008371, dated 01 / 31 / 2023, pp. 87 / 103 72 / 87

[139] Process Stream-2 begins with secondary leaching of the primary leaching residue with the aim of dissolving the Ti minerals from the primary leaching residue in HCl + CaCl2 solution in the presence of a reducing agent. The composition of the primary leaching residue used in the study is given in Table 9. Table 9. Analyses of primary leaching residue used for secondary leaching test work. Secondary leaching feed analyses, % Fe V Ti Al Mn Ca Mg Si 23.18 0.12 27.44 1.35 0.21 0.03 0.02 4.56

[140] The secondary leaching test was carried out in an HCl + CaCl2 solution with ~7M HCl (~21% w / w) and 300 g / L CaCl2 at 75°C with a pulp density of 4.9% w / w for 5 h, adding ~0.59 g of Fe 120 sand per gram of dry primary leaching residue. Metal extraction and leaching liquor analyses are provided in Table 10. Table 10. Metal extraction and leaching liquor analysis from secondary bulk leaching tests with the addition of a reducing agent. Conditions: 300 g / L CaCl2 in HCl + CaCl2 solution with ~7M HCl, 4.9% w / w pulp density and 75°C. Test No. Metal Extraction, % Leaching liquor analysis, g / L Fe V Ti Mn Fe V Ti Al Mn Ca Mg Si SLR-8 92.8 92.1 84.4 94.7 40.0 0.04 12.5 0.06 0.32 100.7 0.42 0.002 SLR-9 92.0 92.6 83.4 93.9 39.4 0.04 11.9 0.06 0.30 88.6 0.43 0.005

[141] Leach extraction was ~93% Fe, ~92% V, ~84% Ti and ~94% Mn, providing liquor analyses of ~40 g / L Fe, 0.04 g / L V, ~12 g / L Ti, 0.3 g / L Mn and 0.43 g / L Mg along with a free acid concentration of ~133 g / L. XRD analyses of the leach cake Petition 870230008371, dated 01 / 31 / 2023, pp. 88 / 103 Secondary analysis of 73 / 87 revealed a minor ilmenite peak with a reasonably high rutile peak, indicating possible precipitation of some Ti dissolved during leaching. Secondary leaching solids analyses were ~6.5% Fe, 0.04% V, ~16.3% Ti, ~3.8% Al, ~16.5% Si, and <0.1% Mn, Ca, and Mg. Cake washing data indicated that two washing stages with 2 to 3 times the cake volume of washing solution may be sufficient to remove most of the entrained leaching liquor, where the second washing liquor yielded an analysis of ~1 g / L Fe, ~0.25 g / L Ti, ~2 g / L Ca, and 1 mg / L V. The leaching liquor from the secondary leaching was stored for downstream processing. 3.4.2 TiO2 precipitation from primary secondary leaching liquor

[142] As the secondary leaching liquor contained mainly Ti(III) chloride, it was oxidized to Ti(IV) chloride with H2O2 before TiO2 precipitation. The H2O2 consumption for the oxidation of Ti(III) chloride was calculated at ~90 kg of H2O2 (30%) per tonne of Ti concentrate, which will be equivalent to 54,000 tonnes of 30% H2O2 consumption per year for processing 600,000 tonnes of Ti concentrate originating from Western Australia.

[143] TiO2 precipitation was carried out at 95°C by hydrolysis of Ti(IV) chloride in hot water with a leach liquor to hot water ratio of ~1. Feed and final liquor analyses and Ti precipitation data are provided in Table 11. Table 11. Feed / final liquor analyses and Ti precipitation data for precipitation tests. Petition 870230008371, dated 01 / 31 / 2023, pp. 89 / 103 74 / 87 of T1O2 by volume at ~95°C Leaching Test No. Liquor Prec. TiO2 Test Liquor Analysis, mg / L % Prec. Ti Fe V Ti Al Mn Ca Mg Si SLR-8 liquid TiP-3 liquid feed 37472 37 12023 59 291 91695 367 4 TiP-3 final liquid 19427 23 256 30 156 44861 198 1 96.0 SLR-9 liquid TiP-4 liquid feed 37399 37 11875 58 283 91542 364 5 TiP-4 final liquid 19591 23 306 29 155 46155 202 2 95.1 SLR-8 + SLR-9 liquid Tip-5 liquid feed 38310 44 11467 55 314 91120 406 5 Tip-5 final liquid 20990 27 665 30 173 49660 229 3 89.3

[144] Over 95% Ti precipitation occurred, yielding ~0.25 g / L of Ti analysis in the final liquor, from the feed liquor containing ~12 g / L of Ti. The mineralogy of precipitated TiO2 was primarily rutile or a mixture of rutile and anatase. The purity of a typical TiO2 sample prepared in the test program was considered very high (> 99.5% purity), where total impurity analyses were 0.24%, which includes elemental analyses of Mg, Ca, Na, K, Al, V, Co, Cr, Cu, Fe, Mn, Mo, Nb, Ni, Pb, Y, Zn, Zr, P, As, Bi, S, and Si. Another TiO2 sample prepared in the test work was also pure (> 98% purity). However, Fe analyses reported higher (< 1%); Except for Fe, the total analyses of all impurities were only ~0.22%. This confirmed that high-purity TiO2 product can be produced from Ti concentrate using this flowchart.

[145] The final liquor was used for further downstream testing work. Petition 870230008371, dated 01 / 31 / 2023, pp. 90-103 75 / 87 3.4.3 Neutralization of the final precipitated liquor with T1O2

[146] The precipitated TiO2 liquor was neutralized with limestone, as free acid analyses reported ~70 g / L to minimize the free acid concentration below 10 g / L. Neutralized liquor analyses reported ~20 g / L of Fe, ~30 to 40 ppm of V / Al, ~0.43 g / L of Ti, 0.2 g / L of Mn / Mg, and 81 g / L of Ca. Ideally, V and Ti will be recovered from the precipitated liquor with TiO2 in this acid neutralization step, raising the pH of the neutralized liquor to precipitate V, Ti, and Al together for further separation. The process step will be identical to the V / Al removal step, as explained in Section 3.3.4 of Process Stream-1.

[147] The treatment of the acid-neutralized liquor had two options: i) evaporation to concentrate the liquor before Fe removal; or ii) Fe removal first before evaporation. In this investigation, Fe removal was chosen first, as evaporation can cause the conversion of Fe(II) to Fe(III), which will need to be reduced again before Fe removal. Therefore, the neutralized liquor was treated for Fe removal in the next step of the process. 3.4.4 Removal of iron from neutralized liquor

[148] The neutralized liquor was used directly for Fe removal under similar conditions to the Fe removal from Stream-1, where complete Fe removal was obtained from the feed liquor with Fe analyses of ~20 g / L.

[149] Three Fe removal tests [FeR(S2)-1 to FeR(S2)3] were carried out at 80°C with an air flow > 5 L / min using limestone as the neutralizing agent. The initial pH was increased by adding lime or limestone before adding air. In the first test, Fe precipitation was carried out Petition 870230008371, dated 01 / 31 / 2023, pp. 91 / 103 76 / 87 using ~20% w / w limestone paste, however, in later tests, 25 to 30% w / w limestone paste was used. The higher density limestone paste was used in later tests to reduce the amount of water from the limestone paste, as any extra water added will need to evaporate at a later stage of the process.

[150] It was found that the behavior of Fe precipitation was almost linear with time (Figure 9), resulting in the complete removal of iron. Similar precipitation behavior was also observed in the Fe removal step in Stream-1. The Fe precipitation kinetics of the third test [FeR (S2) -3] was slightly slower, possibly due to the larger volume (3 L) of feed liquor used compared to the other two tests (feed volume ~ 2.5 L), where the air addition rate was identical for all three tests. V, Ti, and Al precipitated almost completely during the increase of the initial pH to ~4 at 80°C before the addition of air, resulting in analyses of ~1 mg / L of V / Al and ~5 mg / L of Ti in the liquor. The feed and final liquor analyses and the precipitated solids analyses are presented in Table 12 and Table 13, respectively. Table 12. Feed and final liquor analyses of Iron precipitation tests of neutralized liquor precipitated with TiO2 at 80°C using limestone as a neutralizing agent and an air flow > 5 L / min. Feed / Final Liquid Analysis of liquor, mg / L Fe V Ti Al Mn Ca Mg Si Feed liquid 20305 33 436 42 170 81549 206 2 FeR(S2)-1 final liquid 448 0.1 0.5 0.1 83 79141 176 0.8 FeR(S2)-2 final liquid <0.1 <0.1 <0.1 <0.1 74 90123 297 0.1 Petition 870230008371, dated 01 / 31 / 2023, pp. 92-103 77 / 87 Final net FeR(S2)-3 <0.1 <0.1 <0.1 <0.1 74 90664 196 0.1 Table 13. Analysis of precipitated solids for Fe precipitation tests from neutralized liquor precipitated with TiO2. No. Test Fe precipitate analysis, % Fe V Ti Al Mn Ca Mg Si FeR(S2)1 35.0 0.06 0.78 0.07 0.03 12.1 0.01 0.01 FeR(S2)2 37.1 0.06 0.77 0.08 0.08 12.7 0.01 0.06 FeR(S2)3 32.2 0.05 0.65 0.06 0.07 6.0 0.01 0.01

[151] XRD analyses of the Fe(S2)-3 test solid found goethite and magnetite formation during the Fe removal reaction. 3.4.5 Removal of Mg and Mn from liquor removed with Fe and evaporation of liquor removed with Mg / Mn

[152] The liquor removed with Fe was partially evaporated before Mg / Mn removal. The homogenized volume liquor removed with Fe was partially evaporated (~34% by volume) by heating. The Ca concentration increased in the evaporated liquor from ~90 g / L to 146 g / L. This liquor was used for Mg / Mn removal with analyses of ~0.2 g / L Fe, ~0.37 g / L Mg, 0.17 g / L Mn and 146.4 g / L Ca.

[153] Complete Mg / Mn removal was obtained from the feed liquor containing ~0.17 g / L Mn and 0.37 g / L Mg at 60°C, raising the pH of the liquor with lime to ~9-10 and oxidizing the Mn(II) by adding dilute H2O2. Mg and Mn removal was > 99%, yielding 6 mg / L Mg and < 1 mg / L Mn in the final liquor. Analyses of the feed and final liquors from the Mg / Mn removal test are presented in Table 14. Table 14. Feed and final liquor analyses from the test. Petition 870230008371, dated 01 / 31 / 2023, pages 93 / 103 78 / 87 removal of Mg / Mn at 60°C with the addition of lime. Analysis of liquor, mg / L Fe Mn Ca Mg Liquid feed 197 171 146380 368 Final liquid 4.9 0.4 149734 6.1

[154] Ca analyses in the final liquor were ~150 g / L. Analyses of precipitated solids reported ~5% Fe, 4.7% Mn, 10.3% Ca and 11.4% Mg.

[155] The liquor removed with Mg / Mn was further evaporated (~26.5% by volume) to obtain ~231 g / L of Ca concentration in the liquor for the HCl regeneration test work. 3.4.6 Regeneration of HCl from removed liquor with evaporated Mn / Mg

[156] Regeneration of HCl from evaporated liquor was carried out using 53% stoichiometric requirement of H2SO4 at ~85°C, which produced 260 g / L of HCl concentration [20.4% w / w HCl (~7.1 M)] in the final HCl + CaCl2 liquor along with the precipitation of solid anhydride (CaSO4). Washing data from the cake with ~2 times the cake mass using gypsum-saturated water indicated that two washes should be sufficient to recover most of the HCl carried over from the cake. Liquor analyses from the first and second washes reported ~82 g / L of HCl and ~20 g / L of HCl, respectively.

[157] Recycling the regenerated HCl + CaCl2 solution containing 7 M HCl and ~245 g / L CaCl2 for secondary leaching yielded low Ti extraction (67%) along with 91% Fe, 71% V, 7% Al, and 99% Mn extraction. Comparing the leaching data obtained for Fe (~92%) and Ti (83 to 84%) in the SLR-8 / SLR-9 tests, Ti extraction was very low in the HCl + CaCl2 recycling leaching test. Petition 870230008371, dated 01 / 31 / 2023, pp. 94 / 103 79 / 87 The inventors speculate that there could be two reasons for the low Ti extraction: i) low CaCl2 concentration in the liquor (lower total chloride concentration); and ii) inefficient reducing behavior in a small paste mass (650 g) with a small dose (0.5 g / 10 min) of Fe sand addition, as the reaction with the Fe powder likely occurred on the surface of the paste rather than throughout the paste. The inventors believe this result can be improved by further process optimization to regenerate an HCl + CaCl2 solution to achieve >85% Ti extraction.

[158] The test results of all stages of Process Stream-2 confirmed that Stream-2 of the proposed flowchart (Figure 1) is also metallurgically viable. Therefore, this investigation successfully confirmed the operation of the proposed flowchart (Figure 1) for titanium-containing material, in particular, for this Ti concentrate originating from Western Australia. EXAMPLE 2 - Recovery of titanium dioxide from titanomagnetite concentrate 1. Experimental Process

[159] This two-stage leaching technique was applied in this example to a titanium titanomagnetite-containing material to examine its leaching behavior. The vanadium-containing titanomagnetite concentration used in the study was of Australian origin with the composition detailed below. Primary leaching of the concentrate was carried out in HCl solution, while secondary leaching of the primary leaching residue was carried out in a mixed solution of HCl and CaCl2. Petition 870230008371, dated 01 / 31 / 2023, pages 95 / 103 80 / 87 2. Materials and method 2.1 Materials

[160] The analyses of the concentrate are provided in Table 15, which shows 52% Fe, 9.5% Ti, 0.57% V, 1.3% Al, ~2% Si, 0.9% Mg and ~0.3% each of Mn and Ca. Table 15. Analysis of titanomagnetite concentrate Analysis of titanomagnetite concentrate (%) Fe V Ti Al Mn Ca Mg Si 52.0 0.57 9.53 1.32 0.29 0.33 0.94 1.95 2.2 Method 2.2.1 Primary leaching

[161] Primary leaching of the titanomagnetite sample was carried out in a 2 L glass reactor using 20% ​​w / w HCl at 70 to 95°C with 20% w / w pulp density for 2 to 4 h. The reactor was fitted with a glass lid connected to a condenser. The required amounts of HCl solution and concentrate were added to the reactor and placed in an oil bath (PEG 400). The temperature of the oil bath was raised and, once the reaction temperature was reached, a sample was collected and the reaction continued for 2 to 4 hours. Samples were collected every hour and filtered. The solid was initially washed with ~15% HCl solution, followed by repulping / washing with deionized water (DI). At the end of the reaction, the slurry in the reactor volume was filtered; the solid was thoroughly washed and dried at 60°C in an oven. 2.2.2 Secondary leaching

[162] The secondary leaching test was carried out in a 2 L glass reactor using primary leaching residues in a mixed HCl-CaCl2 solution at 70°C in the absence and presence of a reducing agent (Fe 120 sand) for 2 ha 4 h. Petition 870230008371, dated 01 / 31 / 2023, pages 96 / 103 81 / 87 A required quantity of wet primary leaching cake and HCl CaCl2 solution was taken from the reactor, which was fitted with a condenser, thermometer, and ORP probe, and placed in a hot water bath. The reaction was continued for 0.5 h at the test temperature, after which ~1 g of Fe 120 sand was added (when appropriate) manually at regular intervals of ~10 minutes until the end of the reaction under a nitrogen mantle. The online ORP of the reaction was recorded during leaching with the addition of Fet sand. Samples were collected at intervals of 0.5 to 1 h and immediately filtered in a filter press. The solid was initially repulped / washed with 15% w / w HCl followed by repulping / washing with DI water. The final paste was processed similarly to the collected sample. The liquor sample (filtrate) was immediately diluted for analysis to avoid any crystallization that might occur in the leaching liquor after storage at room temperature.The filtered liquor was stored at ~60°C in the oven to prevent crystallization of ferrous chloride for the test where Fe sand was added. 3. Results and Discussion 3.1 Primary leaching

[163] Initially, three primary leaching tests were performed varying the temperature of 70°C, 85°C and 95°C using 20% ​​w / w pulp density in 20.1% w / w HCl solution for 4 h, to examine the dissolution behavior of titanomagnetite concentrate and generate leaching residue for secondary leaching. The extractions of Fe, V and Ti are provided in Figure 10, where the extraction of Fe and V increased 2 h after which it was not. Petition 870230008371, dated 01 / 31 / 2023, pages 97 / 103 82 / 87 significant. The effect of temperature on V extraction was greater at 95°C, resulting in ~97% V extraction in 1 h compared to 70°C and 85°C, where V extraction was ~90%. Figure 10 indicates that Ti dissolution occurred mainly during heating (at 70°C for up to 1 h), after which the dissolved Ti precipitated and was reported in the leaching residue.

[164] Residue analyses for these initial leaching tests are presented in Table 16, which show a decrease in Fe, V, and Al, and an increase in Ti and Si analyses with increasing leaching temperature. Secondary leaching tests of these residues are provided in Section 3.2, where the 70°C and 85°C test residues provided better Ti leaching efficiency compared to the 95°C leaching residue. Ti analyses in the primary test leaching liquor at 70°C reported ~0.12 g / L, which was higher than the Ti analyses for the 85°C test leaching liquor (0.01 g / L). Based on the secondary leaching performance and the Ti analyses of the primary leaching liquor, 85°C for 2 h were chosen as optimal conditions for the additional primary leaching tests.The leaching liquor analyses for the leaching test at 85°C were 111.5 g / L of Fe, 1.4 g / L of V, 0.01 g / L of Ti, 2 g / L of Al, 1.9 g / L of Mg, ~0.29 g / L of Mn, 0.26 g / L of Ca, 0.16 g / L of Si, and ~2 g / L of free HCl. Table 16. Leach residue analyses from primary temperature variation leaching tests. Test temperature Leaching residue analysis %) Fe V Ti Al Mn Mg Si 70°C 29.4 0.16 25.5 1.48 0.51 0.47 3.16 Petition 870230008371, dated 01 / 31 / 2023, pp. 98 / 103 83 / 87 85°C 27.7 0.15 26.0 1.29 0.48 0.39 3.23 95°C 23.8 0.04 32.3 1.27 0.57 0.42 4.23

[165] Another primary leaching test was carried out at 85°C without sampling for 2 h under conditions of 20% w / w pulp density in 20.1% w / w HCl to generate sufficient leaching residue for secondary leaching tests. Leaching extractions are provided in Figure 11 which shows extractions of ~79% Fe, 92% V, 59% Al, ~41% Mn, 82% Mg and ~6% Si. Liquor analyses reported 115.6 g / L Fe, ~1.6 g / L V, 0.04 g / L Ti, 2.2 g / L Al, 0.3 g / L Mn, 0.25 g / L Ca, 1.95 g / L Mg and 0.24 g / L Si in the final leaching liquor. The analyses of the leaching residue showed 30% Fe, 0.13% V, 25.8% Ti, 1.43% Al, 0.45% Mn, 0.41% Ca, 0.42% Mg, and approximately 3.4% Si. 3.2. Secondary leaching 3.2.1 Preliminary secondary leaching

[166] Initially, three secondary leaching tests were carried out at 70°C in a mixed solution of HCl + CaCl2 with 17 to 18% w / w HCl (~6-6.3 M) and 230 to 240 g / L CaCl2 at 2.2% w / w pulp density for 4 h using the residues from the primary leaching tests at 70°C, 85°C and 95°C. No reducing agent was added in these tests. The concentrations of HCl and CaCl2 were kept lower in the mixed HCl + CaCl2 solution (compared to the 20% w / w HCl + 300 g / L CaCl2 solution) for these tests due to the low pulp density (2.2% w / w) used in the leaching. The Ti extraction from these tests is provided in Table 17, which shows Ti extraction > 98.5% from primary leaching residues at 70°C and 85°C, and lower Ti extraction (~91%) from primary leaching residue at 95°C. This indicates that < 85°C was the Petition 870230008371, dated 01 / 31 / 2023, pages 99 / 103 84 / 87 was the optimal temperature for primary leaching of titanomagnetite concentrate to achieve Ti extraction > 98.5% in secondary leaching. Fe extraction was nearly similar (98.5 to 99.6%) for all three primary leaching residues. Mg extraction was ~89-92% for these leaching residues, while Al extraction decreased with increasing primary leaching test temperature. Table 17. Metal extraction from secondary leaching under test conditions of 17 to 18% w / w HCl (~6 to 6.3 M) and 230 to 240 g / L mixed CaCl2 solution, 2.2% w / w pulp density, 70°C and 4 h Primary leaching residue Extraction (%) Fe V Ti Al Mn Mg Residue from test at 70°C 98.5 98.6 43.0 89.3 Residue from test at 85°C 99.6 100.0 98.8 35.0 99.5 92.4 Residue from test at 95°C 99.3 90.6 14.3 90.3

[167] Ti analyses of secondary leaching liquors are provided in Figure 12 which shows a slightly higher Ti analysis for the test with leaching residue at 85°C, otherwise the Ti analyses were nearly similar (6.7 to 7.7 g / L). The Ti analysis data indicate that most of the Ti leaching occurred within 1 h of the reaction with a slight further increase up to 2 h, after which the Ti concentration remained similar. This indicates that 2 hours of leaching should be sufficient to extract most of the Ti from the primary leaching residues. Therefore, further secondary leaching tests were carried out for 2 h. 3.2.1 Leaching at higher pulp density

[168] Other secondary leaching tests were Petition 870230008371, dated 01 / 31 / 2023, pp. 100 / 103 Leaching tests (85 / 87) were performed in the absence and presence of Fe 120 sand at a higher pulp density of 6.2% w / w to examine the effect of the reducing agent and leaching efficiency at higher pulp density. Leaching tests were performed using primary leaching residue at 85°C under the test conditions of ~20% w / w HCl with 300 g / L of mixed CaCl2 solution, 70°C, and 2 h. Leaching extractions are provided in Table 18. Metal extraction in the presence of reducing agent was slightly better, except for Al and Mg, compared to its absence. Ti extractions were 89.8% and 91.2% in the absence and presence of Fe 120 sand, respectively. Analyses of the leaching liquor and leaching residues are provided in Table 19 and Table 20, respectively. Tabela 18. Extração de metais na lixiviação secundária sob as condições de teste de 6,2% p / p de densidade de polpa, ~20% p / p de HCl com 300 g / L de solução mista de CaCl2, 70°C e 2 h Added Fe 120 sand (g / 100 g of secondary leaching solids) Extraction (%) Fe V Ti Al Mn Mg 89.3 92.7 89.8 24.5 91.4 22.8 14.1 94.3 94.8 91.2 17.1 93.7 22.5 Table 19. Analysis of the leaching liquor from secondary leaching under test conditions of 6.2% w / w pulp density, ~20% w / w HCl with 300 g / L mixed CaCl2 solution, 70°C and 2 h Added Fe 120 sand (g / 100 g of leaching solids) Leaching liquor analysis (mg / L) Fe V Ti Al Mn Ca Mg Petition 870230008371, dated 01 / 31 / 2023, pages 101 / 103 86 / 87 secondary) 26048 109 19430 218 429 108379 126 14.1 41006 116 19516 200 495 99936 139 Table 20. Solid leaching analyses of secondary leaching under test conditions of 6.2% w / w pulp density, ~20% w / w HCl with 300 g / L mixed CaCl2 solution, 70°C and 2 h Added Fe 120 sand (g / 100 g of secondary leaching solids) Leaching solids analysis (%) Fe V Ti Al Mn Mg Si 5.35 0.03 9.88 5.80 0.05 1.64 21.27 14.1 5.40 0.03 9.66 5.95 0.05 1.45 22.40 4. Conclusions

[169] It was found that the two-stage leaching process is suitable for titanomagnetite concentrate to obtain high Ti extraction in secondary leaching in the presence and absence of Fe powder as a reducing agent. Titanium extractions were ~90% and 91% with and without reducing agent under test conditions of 6.2% w / w pulp density, ~20% w / w HCl with 300 g / L CaCl2 mixed solution, 70°C and 2 h yielding Ti analyses in the liquor ~19.5 g / L. The addition of Fe powder during secondary leaching may be considered a better option, as Fe in the leaching liquor needs to be present as ferrous before the leaching liquor can be treated for TiO2 precipitation.

[170] The optimum parameters for primary leaching of titanomagnetite were 85°C and 2 h in 20% w / w HCl solution at 20% pulp density where extractions of ~79% Fe, 92% V, 5 9% Al, ~41% Mn, 82% Mg and ~6% Si occurred.

[171] Those skilled in the art will appreciate that the invention Petition 870230008371, dated 01 / 31 / 2023, pages 102 / 103 The invention described herein is subject to variations and modifications beyond those specifically described. It is understood that the invention includes all such variations and modifications that fall within the spirit and scope of the present invention.

[172] When the terms includes, comprise, composed(s) or comprising are used in this descriptive report (including the claims), they shall be interpreted as specifying the presence of the stated features, whole numbers, steps or components, but not excluding the presence of one or more other features, whole numbers, steps, components or groups thereof. Petition 870230008371, dated 01 / 31 / 2023, page 103 / 103

Claims

1 / 11 CLAIMS 1. Process for recovering titanium dioxide from a titanium-containing material, characterized in that the process includes the steps of: leaching the titanium-containing material in a first leaching step at atmospheric pressure and at a temperature of 70 to 97°C with a first leach to produce a first leaching solution comprising first undissolved leach solids including a titanium content and a first leach liquor, the first leach comprising hydrochloric acid at a concentration of less than 23% w / w; separating the first leach liquor and the first undissolved leach solids;leach the first leaching solids in a second leaching stage at atmospheric pressure and a temperature of 60 to 80°C with a second leaching agent in the presence of a powdered Fe reducing agent to produce a second leaching solution comprising undissolved second leaching solids and a second leaching liquor that includes a leached titanium content and an iron content, the second leaching agent comprising a mixed chloride solution comprising less than 23% w / w hydrochloric acid and an additional chloride selected from alkali metal chlorides, magnesium chloride and calcium chloride, or mixtures thereof; separate the second leaching liquor and the undissolved second leaching solids;precipitate titanium dioxide from the second leaching liquor by adding heated or boiling water under an inert gas or nitrogen atmosphere to increase the temperature of the second leaching liquor to 85 to 100°C to produce a second treated leaching liquor and a solid containing titanium dioxide; separate the solid containing titanium dioxide from the second treated leaching liquor; precipitate the iron content of the second treated leaching liquor by adding a neutralizing agent and an oxidizing agent to the second treated leaching liquor at a temperature of 70 to 90°C to increase the pH of the second leaching liquor to 4 to 8 to produce a slurry with removed iron comprising a second leaching liquor with removed iron and a solid precipitate of iron; Separate the second leaching liquor containing the removed iron from the solid iron precipitate;and regenerate the second leachate to recycle it for the second leaching stage, thus recovering the titanium from the second leaching solution as titanium dioxide.

2. Process according to claim 1, characterized in that the first leaching step is conducted with the first leach comprising 20 to 22% w / w of HCl solution, preferably at 85 to 97°C.

3. A process according to claim 1 or 2, characterized in that the titanium-containing material includes at least one valuable metal selected from iron, vanadium, manganese, magnesium, or aluminum, and the first leaching liquor is subjected to steps to recover at least one valuable metal from it.

4. Process according to claim 3, Petition 870220108356, dated 11 / 23 / 2022, page 12 / 23 3 / 11 characterized in that at least one valuable metal includes vanadium and / or aluminum, and the process further comprises a vanadium and / or aluminum removal step comprising: adding a neutralizing agent, preferably at least one of limestone, lime or MgO, to the first leaching liquor at a temperature of 50 to 80°C under an inert gas or nitrogen atmosphere, to increase the pH of the liquor to 3 to 6, thereby precipitating vanadium and aluminum to produce a paste with V / Al removed; and separating the paste with V / Al removed into a liquid fraction comprising a liquor with V / Al removed and a solid fraction comprising the solid precipitate of V / Al.

5. Process according to claim 3 or 4, characterized in that at least one valuable metal includes iron, and the process further comprises an iron removal step comprising: adding a neutralizing agent, preferably at least one of limestone, lime or MgO, and an oxidant to the first leaching liquor at a temperature of 70 to 90°C to increase the pH of the liquor to 4 to 7, thereby precipitating the iron to produce a paste with removed iron; and separating the paste with removed iron into a liquid fraction comprising a liquor with removed iron and a solid fraction comprising the solid iron precipitate.

6. Process according to claim 5, characterized in that the oxidant comprises at least one of alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid or an oxygen-containing gas, preferably at least one of hydrogen peroxide or an oxygen-containing gas, more preferably oxygen or air.

7. Process according to claim 5 or 6, characterized in that the iron removal step is carried out after the vanadium and / or aluminum removal step.

8. A process according to any one of claims 3 to 7, characterized in that at least one valuable metal includes manganese and / or magnesium, and the process further comprises a manganese and / or magnesium removal step comprising: adding a neutralizing agent, preferably lime, and an oxidizing agent, preferably H2O2, or an oxygen-containing gas, more preferably air, to the liquor with removed iron at a temperature of 60 to 90°C to increase the pH of the liquor to 9 to 10, thereby precipitating Mg and / or Mn to produce a paste with removed Mg / Mn; and separating the paste with removed Mg / Mn into a liquid fraction comprising a liquor with removed Mg / Mn and a solid fraction comprising the solid precipitate of Mg and / or Mn.

9. Process according to claim 8, characterized in that the manganese and / or magnesium removal step is carried out after the iron removal step.

10. A process, according to any of the preceding claims, characterized in that it further comprises: regenerating the first leachate and recycling the first leachate for the first leaching stage.

11. Process, according to claim 10, characterized in that the first leach is regenerated by: concentrating the chloride content of the liquor with Mg / Mn removed by removing water, preferably by boiling and / or evaporation, to produce an evaporated liquor; reacting the evaporated liquor with at least 98% w / w sulfuric acid at a temperature of 30 to 90°C, preferably 80 to 85°C under atmospheric conditions to produce 20 to 22% w / w hydrochloric acid and a solid precipitate; separating the solid precipitate and the hydrochloric acid liquor; and recycling the hydrochloric acid liquor for the first leaching step.

12. Process, according to claim 11, characterized in that the chloride content comprises calcium chloride and the reaction between the evaporated liquor and concentrated sulfuric acid is carried out in a temperature range of 80 to 85°C aiming to precipitate only anhydride.

13. Process, according to any of the preceding claims when dependent on claim 4, characterized in that it further comprises the following steps before the precipitation of vanadium and aluminum from the first leaching liquor: neutralizing at least part of the free acid (HCl) in the first leaching liquor by adding to the first leaching liquor at least one of: titanium-containing feed material, limestone, lime or MgO, to produce a first neutralized liquor paste including a neutralized leaching solid; and separating the first neutralized liquor paste into a solid fraction comprising the neutralized leaching solid and a liquid fraction comprising the first neutralized leaching liquor.

14. Process according to claim 13, characterized in that it further comprises the following steps after the neutralization steps: reducing the first neutralized leaching liquor at 45 to 75°C by adding metallic iron, preferably iron powder, to convert ferric chloride in the first leaching liquor into ferrous chloride; and separating the first reduced leaching liquor into a liquid fraction comprising a reduced liquor and a solid fraction comprising any unreacted solid iron powder.

15. Process according to claim 14, characterized in that the reduction is conducted under an inert gas or nitrogen atmosphere, preferably under a nitrogen mantle, and achieves an oxidation-reduction potential (ORP) of the liquor below 100 mV.

16. A process according to any of the preceding claims, characterized in that the iron is substantially precipitated as magnetite, preferably precipitated only as magnetite.

17. Process, according to any of the preceding claims, characterized in that the second leaching step is conducted with a second leach comprising a mixed chloride solution of 20 to 22% w / w HCl and the additional chloride with a total chloride concentration of 400 to 550 g / L, preferably at 70 to 80°C.

18. Process, according to any of the previous claims, characterized by the fact that the second leaching stage is conducted for 2 to 6 hours.

19. A process, according to any of the preceding claims, characterized in that the second leaching stage includes two leaching regimes, comprising: a first leaching regime carried out in the mixed chloride solution (without any addition of iron powder); and a second leaching regime carried out in the mixed chloride solution with the addition of iron powder.

20. Process according to claim 19, characterized in that the first leaching regime and the second leaching regime of the second leaching stage are conducted as successive leaching stages (i) in the same leaching stage / container; or (ii) in separate leaching stages / containers.

21. Process, according to claim 19 or 20, characterized in that the first leaching regime is carried out for a duration of 1 to 2 hours and the second leaching regime for a duration of 1 to 4 hours.

22. A process, according to any of the preceding claims, characterized in that the neutralizing agent added to the second treated leaching liquor to precipitate the iron content therefrom comprises at least one of limestone, lime or MgO.

23. Process, according to any of the preceding claims, characterized in that the oxidant added to the second treated leaching liquor to precipitate the iron content thereof comprises alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid, an oxygen-containing gas or mixtures thereof, preferably at least one of hydrogen peroxide or an oxygen-containing gas, more preferably oxygen or air.

24. A process according to any of the preceding claims, characterized in that it further comprises: introducing an oxidant into the second leaching liquor before the titanium dioxide precipitation step to oxidize any Ti(III) content to Ti(IV) by controlling the oxidation-reduction potential of the second leaching liquor within 100 to 200 mV, wherein the oxidant is selected from air, oxygen, alkali metal peroxide, alkali metal perchlorate, ammonium perchlorate, magnesium perchlorate, magnesium chlorate, alkali metal chlorate, chlorine, alkali metal hypochlorite, hydrogen peroxide, perchloric acid, other non-sulfur-containing oxidants, or mixtures thereof.

25. Process according to claim 24, characterized in that the oxidant comprises hydrogen peroxide.

26. Process, according to any of the preceding claims, characterized in that the titanium dioxide precipitation step comprises hydrolyzing the Ti(IV) content of the second leaching liquor to precipitate it as solid titanium dioxide (TiO2) under an inert gas or nitrogen atmosphere, preferably under a nitrogen mantle.

27. A process according to any of the preceding claims, characterized in that it further comprises the steps of: adding a neutralizing agent, preferably at least one of limestone, lime or MgO, to the second leaching liquor treated at a temperature of 50 to 80°C under an inert gas or nitrogen atmosphere, to increase the pH of the liquor to 3 to 6, thereby precipitating the vanadium and aluminum to produce a paste with V / Al removed; and separating the paste with V / Al removed into a liquid fraction comprising a second leaching liquor treated with V / Al removed and a solid fraction comprising the solid precipitate of V / Al.

28. A process according to any of the preceding claims, characterized in that it further comprises the steps of: adding a neutralizing agent, preferably lime, and an oxidant, preferably H2O2, or oxygen-containing gas, more preferably air, to the liquor with iron removed at a temperature of 60 to 90°C to increase the pH of the liquor to 9 to 10, thereby precipitating Mg and / or Mn to produce a paste with Mg / Mn removed; and separating the paste with Mg / Mn removed into a liquid fraction comprising a liquor with Mg / Mn removed and a solid fraction comprising the solid precipitate of Mg and / or Mn.

29. Process, according to any of the preceding claims, characterized in that the regeneration step of the second leachate for recycling the second leaching stage comprises: Petition 870220108356, dated 11 / 23 / 2022, page 19 / 23 10 / 11 concentrating the chloride content of the second treated leaching liquor by removing water, preferably by boiling and / or evaporation, to produce a concentrated chloride solution; reacting the evaporated liquor with at least 98% w / w sulfuric acid at a temperature of 30 to 90°C, preferably 80 to 85°C under atmospheric conditions to produce a mixed chloride solution with 20 to 22% w / w hydrochloric acid, an additional chloride content in the solution and a solid precipitate; separating the solid precipitate from the mixed chloride solution; and recycle the mixed chloride solution for the second leaching stage.

30. Process according to claim 29, characterized in that the chloride content comprises calcium chloride and the reaction between the evaporated liquor and concentrated sulfuric acid is carried out in a temperature range of 80 to 85°C aiming to precipitate only anhydride.

31. A process, according to any of the preceding claims, characterized in that the process steps of the first leaching liquor treatment stages and the second leaching liquor treatment stages are combined into at least one of the following steps: vanadium and / or aluminum removal; iron removal; or manganese and / or magnesium removal.

32. Process, according to any of the preceding claims, characterized in that the neutralizing agent in the process comprises MgO, and the process further comprises a Mg removal step, in which Mg(OH)2 is precipitated using lime and an MgO regeneration stage, in which Mg(OH)2 is calcined, preferably at 300 to 400°C, to regenerate MgO for recycling as a neutralizing agent in the process.

33. A process, according to any of the preceding claims, characterized in that the titanium-containing material comprises at least one of: a. a titanium-containing ore material including titanium-containing ore or mineral deposit, concentrate thereof, modified ore thereof and tailings thereof, and mixtures thereof; b. a mineral deposit containing titanium minerals, such as ilmenite, rutile and / or leucoxene; c. vanadium associated with titanium minerals, such as titanomagnetite, vanadium-containing minerals; d. titanium-containing leaching residues and slags; or e. mineral processing residues.

34. A process, according to any of the preceding claims, characterized in that the titanium-containing material is a titanium ore, concentrate thereof, modified ore thereof and tailings thereof, and mixtures thereof.

35. A process, according to any of the preceding claims, characterized in that the titanium-containing material includes at least one of ilmenite or titanomagnetite.

36. Titanium dioxide, characterized by being produced from a process as defined in any of the preceding claims. Petition 870220108356, dated 11 / 23 / 2022, pp. 21 / 23

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