Method for Recovering Iron from Titanium concentrate

Abstract

The present invention relates to a method for recovering iron metal by reducing hematite in titanium concentrate to iron metal and converting TiO₂ into sodium titanate by mixing a sodium salt and a carbonaceous reducing agent with titanium concentrate and heat treating it. According to the present invention, an iron removal rate of 95% or more can be achieved from low-grade titanium concentrate, the recovered iron can be recycled as a raw material for ironmaking in the form of ingots, and the residue from which iron has been removed can be utilized as a raw material for producing high-grade TiO₂.

Description

Technology Field

[0001] The present invention relates to a method for recovering iron from titanium concentrate, and more specifically, to a method for reducing and recovering hematite in the concentrate into iron metal by mixing a sodium salt and a carbonaceous reducing agent with titanium concentrate containing hematite (Fe2O3) and heat-treating it at a high temperature. Background Technology

[0003] Titanium (Ti) is utilized in various industrial fields, such as aerospace, the chemical industry, and medical devices, due to its excellent properties, including lightweightness, high strength, and corrosion resistance. Titanium concentrate, which serves as the raw material for titanium manufacturing, generally exists in the form of ilmenite (FeTiO₃) or rutile (TiO₂).

[0004] Ti concentrate, produced through the beneficiation process from raw Ti ore, is mined and used in a form containing various minerals in addition to ilmenite, depending on the geological characteristics and changes of the ore's location and climatic conditions; consequently, the applicable smelting methods differ depending on the types of minerals contained in the Ti concentrate.

[0005] Although Ti ore is deposited in the Myeonsan Formation of Taebaek, Gangwon-do, the Ti concentrate recovered from the raw Ti ore of the Myeonsan Formation consists of a mixture of hematite (Fe2O3) and rutile (TiO2), and is characterized by a high content of Fe (40–70 wt%) and silica (SiO2) compared to commercially utilized Ti concentrate.

[0006] Furthermore, iron in the Mianshan layer titanium concentrate exists in the form of hematite (Fe2O3) rather than ilmenite (FeTiO₃), so removing it through a conventional wet leaching process requires a lot of energy and a large amount of acid, which results in a high environmental burden and low economic feasibility.

[0007] Therefore, in order to develop smelting technology tailored for Ti concentrate mined from the Taebaek Myeonsan Formation, it is required to develop an eco-friendly and economical process technology capable of producing high-grade titanium compounds by recovering Fe as a metal byproduct rather than removing it from the Myeonsan Formation Ti concentrate. Prior art literature

[0009] Korean Patent Publication No. 10-1389430 (Published on April 25, 2014) The problem to be solved

[0010] The present invention aims to solve the above-mentioned problems by providing a method to efficiently recover iron (40-70 wt%) from titanium concentrate and simultaneously improve the titanium grade in the concentrate.

[0011] In addition, the present invention aims to provide a method for recovering the recovered iron in the form of ingots for resource recovery, and utilizing the residue from which the iron has been removed as a raw material for the production of high-purity titanium dioxide (TiO2).

[0012] In addition, the present invention aims to provide an iron recovery method that minimizes environmental burden and improves economic efficiency.

[0014] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0016] To achieve the above objective, the present invention provides a method for recovering iron from titanium concentrate, comprising the steps of: (a) mixing a sodium salt and a carbonaceous reducing agent with titanium concentrate containing hematite (Fe2O3); (b) heat-treating the mixture at a temperature of 1400K or higher to reduce the hematite in the concentrate to iron metal through carbon reduction and convert TiO₂ in the concentrate to sodium titanate; and (c) recovering the iron metal.

[0017] According to one embodiment of the present invention, the titanium concentrate comprises hematite (Fe2O3, 40-70 wt%) and rutile (TiO2, It may be a concentrate containing 10 to 40 wt%, but Fe and Ti in the concentrate may exist as complex oxides such as FeTiO3.

[0018] According to another embodiment of the present invention, the titanium concentrate may be a cotton acid layer titanium concentrate.

[0019] According to another embodiment of the present invention, the sodium salt may be sodium carbonate (Na2CO3), sodium sulfate (Na2SO4), caustic soda (NaOH), or a mixture thereof.

[0020] According to another embodiment of the present invention, the sodium salt may be mixed with titanium concentrate in a weight ratio of 1:0.5 to 2.0.

[0021] According to another embodiment of the present invention, the carbonaceous reducing agent may be mixed with titanium concentrate in a weight ratio of 1:0.05 to 0.4.

[0022] According to another embodiment of the present invention, the sodium salt is sodium carbonate (Na2CO3) and can be mixed in a weight ratio of 0.8 to 3, preferably 1.0 to 2.0, relative to titanium concentrate.

[0023] According to another embodiment of the present invention, the heat treatment temperature may be 1400 to 1800K, preferably 1500 to 1700K, and more preferably 1600K.

[0024] According to another embodiment of the present invention, the heat treatment may be performed for 3 to 15 hours, preferably 5 to 10 hours, and more preferably 5 hours.

[0025] According to another embodiment of the present invention, the heat treatment may be performed in an inert atmosphere or a reducing atmosphere. The inert atmosphere may be an atmosphere such as argon (Ar) or nitrogen (N₂).

[0026] According to another embodiment of the present invention, the recovery of iron metal in step (c) may be performed by gravity separation in a molten state, magnetic separation after cooling, or a combination thereof.

[0027] According to another embodiment of the present invention, the recovered iron metal is in the form of an ingot, and the iron removal rate of the titanium concentrate may be 95% or more, preferably 99% or more.

[0028] According to another embodiment of the present invention, after step (c), the method may further include step (d) of leaching the residue from which iron has been removed to produce high-grade titanium dioxide.

[0029] In addition, the present invention provides a roasting composition for recovering iron from titanium concentrate comprising titanium concentrate containing TiO₂ and Fe2O3; a sodium salt; and a carbonaceous reducing agent, wherein the weight ratio of titanium concentrate: sodium salt: carbonaceous reducing agent is 1: 0.5 to 2.0: 0.05 to 0.4.

[0030] According to one embodiment of the present invention, the sodium salt is Na2CO3, and the weight ratio of the titanium concentrate: Na2CO3: carbonaceous reducing agent may be 1: 0.8~1.5: 0.05~0.2.

[0031] In addition, the present invention provides an iron metal ingot recovered by the above method.

[0032] In addition, the present invention provides a use for using the iron metal recovered by the above method as a raw material for an ironmaking process.

[0033] In addition, the present invention provides a use for the residue from which iron has been removed by the above method as a raw material for manufacturing high-quality titanium dioxide. Effects of the invention

[0035] According to the present invention, iron can be efficiently recovered from titanium concentrate of the cotton oxide layer. In particular, the iron removal rate is excellent at 95% or higher, and the recovered iron can be recycled into an ingot form.

[0036] In addition, by converting the titanium in the concentrate into the form of sodium titanate through a soda roasting process, the residue from which iron has been removed can be utilized as a raw material for manufacturing high-quality titanium dioxide.

[0037] In addition, compared to the existing wet leaching process, iron in the concentrate can be recovered without using acid, thereby minimizing environmental burden and improving economic efficiency.

[0038] In addition, high-quality and high-purity TiO₂ can be ultimately produced from the iron-removed residue, which can be utilized for various applications such as pigments, catalysts, and electronic materials.

[0039] In addition, it is advantageous in terms of resource acquisition as it allows for the effective utilization of titanium concentrate from the Myeonsan Formation, a domestic resource.

[0041] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description of the invention or the claims. Brief explanation of the drawing

[0043] Figure 1 shows an overall process flowchart of a method for recovering iron from titanium concentrate according to one embodiment of the present invention. Figure 2 shows a detailed flowchart of the Fe recovery process from titanium concentrate according to one embodiment of the present invention. Figure 3 shows the X-ray Diffraction (XRD) analysis results of the titanium concentrate of the pyrotechnic layer, and the crystal phases of TiO₂, Fe2O3, and SiO₂ can be confirmed. Figure 4 shows a schematic diagram and actual photograph of the experimental apparatus used in the soda roasting process. Figure 5 shows a photograph of Fe metal ingots recovered after the soda roasting process, showing the results under various Na2CO3 and carbon mixing ratio conditions. Figure 6 shows the results of Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) analysis of Fe ingots recovered after the soda roasting process, showing that the recovered Fe ingots are an alloy of the Fe-C type. Figure 7 shows the XRD analysis results of the powder recovered from the carbon cover after the soda roasting process, which confirms the volatilization of unreacted Na2CO3. Figure 8 shows the XRD analysis results of the soda roasting residue of low-grade cotton acid layer Ti concentrate according to the amount of Na2CO3 used, showing the results under weight ratio conditions of (a) concentrate:Na2CO3 (1:1) and (b) concentrate:Na2CO3 (1:2). Specific details for implementing the invention

[0044] Preferred embodiments according to the present invention will be described in detail below with reference to the attached drawings. However, in describing the present invention, if it is determined that related known technologies, etc., may obscure the essence of the present invention, a detailed description thereof will be omitted.

[0045] The advantages and features of the present invention and the methods for achieving them will become clear by referring to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited by the embodiments disclosed below but can be implemented in various different forms. These embodiments are provided merely to ensure that the disclosure of the present invention is complete and to fully inform those skilled in the art of the scope of the invention, and the present invention is defined only by the scope of the claims.

[0046] The present invention will be described in detail below.

[0048] The terms used in this specification have been selected to be as widely used as possible, taking into account their functions in the present invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Therefore, the terms used in this specification should be defined not merely by their names, but based on their meanings and the overall content of the present invention.

[0050] The present invention relates to a method for recovering iron from titanium concentrate containing hematite (Fe2O3) and rutile (TiO2). By combining a soda roasting process using a sodium salt with a carbon reduction reaction, the method of the present invention can effectively separate the two by reducing the hematite in the concentrate to iron metal and simultaneously converting titanium into sodium titanate.

[0051] The concentrates commonly used in the global titanium industry are typically ilmenite (FeTiO₃) or rutile (TiO₂), which occur in the form of sand or rock ore. Ilmenite typically has a TiO₂ content of 45–65 wt%, while rutile has a content of 90–96 wt%. These high-grade concentrates are mainly found in Australia, South Africa, Canada, China, and India, and are used as key raw materials for the production of titanium products worldwide.

[0052] In a preferred embodiment of the present invention, low-grade titanium concentrate produced from Myeonsan Formation titanium ore deposited in Taebaek, Gangwon-do is used. Unlike general titanium concentrate, low-grade Myeonsan Formation titanium concentrate has the following characteristics, making direct application to existing processes difficult. The TiO₂ content of low-grade Myeonsan Formation concentrate is approximately 20–25 wt%, which is significantly lower than that of commercially used ilmenite (45–65 wt%) or rutile (90–96 wt%). Furthermore, low-grade Myeonsan Formation titanium concentrate is characterized by the iron component existing in the form of hematite (Fe2O3) rather than ilmenite (FeTiO3), and by a high content of gangue components such as SiO2. According to XRD analysis results, it can be confirmed that the major mineral phases within the Myeonsan Formation titanium concentrate include rutile (TiO2), hematite (Fe2O3), and silica (SiO2).

[0053] Due to these mineralogical characteristics, efficient separation of iron and titanium is difficult using traditional smelting methods; however, in this invention, a soda roasting process is performed at high temperatures by mixing a carbonaceous reducing agent with a sodium salt. During this process, hematite (Fe2O3) is reduced to iron metal (Fe) by carbon and aggregates into an ingot form, while the titanium component reacts with the sodium salt to form sodium titanate (Na2TiO3 or Na4Ti5O). 12By converting to ), effective separation using the difference in specific gravity between the two phases in the molten state becomes possible.

[0055] Accordingly, the present invention provides a method for recovering iron from titanium concentrate comprising: (a) mixing a sodium salt and a carbonaceous reducing agent with titanium concentrate containing hematite (Fe2O3); (b) heat-treating the mixture at a temperature of 1400K or higher to reduce the hematite in the concentrate to iron metal through carbon reduction and convert TiO2 in the concentrate to sodium titanate; and (c) recovering the iron metal.

[0056] Figure 1 shows an overall process flowchart of a method for recovering iron from titanium concentrate according to one embodiment of the present invention.

[0057] As illustrated in FIG. 1, the method of the present invention comprises (a) a mixing step (S100), (b) a heat treatment step (S200), and (c) an iron metal recovery step (S300).

[0059] (a) Mixing step (S100)

[0060] In this step, a titanium concentrate containing hematite (Fe2O3) is mixed with a sodium salt or a sodium salt containing caustic soda (NaOH) and a carbonaceous reducing agent.

[0061] In this specification, 'sodium salt' means an inorganic compound containing sodium, and is used to include not only salts such as sodium carbonate and sodium sulfate, but also bases such as sodium hydroxide.

[0062] The titanium concentrate used in the present invention is preferably a concentrate in which Fe is the main impurity. More specifically, the titanium concentrate may contain various forms of Fe as impurities, such as FeO, Fe3O4, Fe2O3, and FeTiO2; most preferably, a low-grade cotton acid layer titanium concentrate containing Fe2O3 may be used, but is not limited thereto.

[0063] Low-grade cotton acid layer titanium concentrate may have a composition of, for example, about 23.4 wt% TiO₂, about 56.9 wt% Fe2O3, about 11.4 wt% SiO₂, about 4.02 wt% Al2O₃, about 1.79 wt% MgO, about 1.08 wt% K2O, about 0.58 wt% CaO, about 0.29 wt% MnO, about 0.04 wt% P2O5, and about 0.05 wt% Na2O.

[0064] Referring to Figure 3, XRD analysis of the titanium concentrate of the Mianshan layer reveals peaks of TiO₂ (rutile), Fe₂O₃ (hematite), and SiO₂ (quartz).

[0065] Sodium salts play a role in converting TiO₂ in the concentrate into sodium titanate during the soda roasting process. The sodium salt may be sodium carbonate (Na2CO3), sodium sulfate (Na2SO4), caustic soda (NaOH), or a mixture thereof, and most preferably, sodium carbonate (Na2CO3) may be used, but is not limited thereto.

[0066] The mixing ratio of the sodium salt is mixed at a weight ratio of 0.5 to 2.0 relative to the titanium concentrate, preferably 1.0 to 1.5. More specifically, the weight ratio of titanium concentrate to sodium salt can be mixed at 1:0.5 to 2.0, preferably 1:1.0 to 1.5, and most preferably 1:1. If the amount of sodium salt used is too small, the soda conversion of TiO₂ does not proceed sufficiently, and if it is too large, an excess amount of sodium salt volatilizes or scatters, reducing economic efficiency.

[0067] Carbonaceous reducing agents serve to reduce hematite (Fe2O3) in the concentrate to iron metal at high temperatures. Carbonaceous reducing agents may include graphite, coke, activated carbon, carbon black, charcoal, etc., and preferably graphite may be used, but is not limited thereto. The particle size of the carbonaceous reducing agent is not particularly limited, but it is preferable to use it in the form of a fine powder to increase reaction efficiency. The preferred particle size may be 1 to 100 μm based on D50, more preferably 5 to 50 μm, but is not limited thereto.

[0068] The mixing ratio of the carbonaceous reducing agent is 0.05 to 0.4 by weight relative to the titanium concentrate, preferably 0.05 to 0.3 by weight, and most preferably 0.1 to 0.2 by weight. More specifically, the weight ratio of titanium concentrate to carbonaceous reducing agent can be 1:0.05 to 0.4, preferably 1:0.1 to 0.2. If the amount of carbonaceous reducing agent used is too small, the reduction of hematite does not proceed sufficiently, and if it is too large, unreacted reducing agent may exist between the reduced iron metals, hindering aggregation into ingots.

[0069] In one embodiment, the weight ratio of titanium concentrate:Na2CO₃:carbonaceous reducing agent can be mixed in a ratio of 1:0.8 to 1.5:0.05 to 0.3, most preferably 1:1:0.1.

[0071] (b) Heat treatment step (S200)

[0072] In this step, the above mixture is heat-treated at a temperature of 1400K or higher to reduce the hematite in the concentrate to iron metal through carbon reduction and convert the TiO₂ in the concentrate into sodium titanate.

[0073] Figure 4 shows a schematic diagram and actual photograph of the experimental apparatus used in the soda roasting process. As shown in Figure 4, the heat treatment apparatus is: Alumina reactor: a cylindrical reactor made of alumina (Al₂O₃) material capable of withstanding high temperatures. The reactor is installed inside an electric furnace.

[0074] Carbon crucible: A container for holding mixtures, using a graphite crucible. Graphite crucibles have excellent high-temperature resistance and are non-reactive with sodium salts.

[0075] Carbon lid: A lid placed over a graphite crucible, also made of graphite. The lid serves to control the reaction atmosphere, prevent scattering of the mixture, and maintain a reducing atmosphere.

[0076] Silicone plug: A silicone stopper that seals the top of an alumina reactor.

[0077] Argon gas supply line (Ar gas): This is an argon gas supply line used to maintain an inert atmosphere inside the reactor.

[0078] Exhaust gas line: This is a line that discharges gases (CO, CO₂, etc.) generated during the reaction.

[0079] The heat treatment temperature is 1400K or higher, preferably 1400 to 1800K, more preferably 1500 to 1700K, and most preferably 1600K. If the heat treatment temperature is below 1400K, the reduced iron metal cannot melt to form a liquid phase, making it difficult to recover as an ingot, and if it exceeds 1800K, problems with the heat resistance of the device and increased energy costs may occur.

[0080] The heat treatment time is 3 to 15 hours, preferably 5 to 10 hours. If the heat treatment time is too short, the reaction is incomplete, and if it is too long, economic efficiency decreases.

[0081] Heat treatment is performed in an inert atmosphere or a reducing atmosphere. Gaseous atmospheres such as argon (Ar) or nitrogen (N₂) may be used as the inert atmosphere, and preferably, heat treatment is performed in an argon atmosphere.

[0082] Electric furnaces, gas furnaces, etc., can be used as heat treatment devices. The mixture can be heat-treated by being loaded into a heat-resistant container such as a carbon crucible, and the reaction atmosphere can be controlled by covering the top of the mixture with a carbon lid.

[0083] In this heat treatment step, the reduction reaction of hematite by carbon takes place:

[0084] 2Fe2O3 + 3C → 4Fe + 3CO2

[0085] Through this reaction, hematite in the concentrate is reduced to iron metal (Fe metal). The reduced iron metal becomes molten at high temperatures and sinks to the bottom due to density differences, aggregating to form an ingot.

[0086] In addition, the soda reaction of TiO₂ by sodium salts occurs:

[0087] TiO₂ + Na2CO3→Na2TiO₃ + CO₂

[0088] Through this reaction, TiO₂ in the concentrate becomes Na2TiO₃, Na4Ti5O 12 , Na8Ti5O 14 It is converted into sodium titanate. Sodium titanate melts at high temperatures and separates from iron metal.

[0089] In addition, gangue components such as SiO₂ and Al2O₃ in the concentrate also react with sodium salts to be converted into sodium silicate (Na2SiO₃, Na2Si2O₅) and sodium aluminate (NaAlO₂).

[0090] When cooled after heat treatment, the iron metal solidifies into an ingot form and becomes physically separated from the residue, which is mainly composed of sodium titanate.

[0092] (c) Iron metal recovery step (S300)

[0093] In this step, iron metal is recovered from the heat treatment product.

[0094] The recovery of ferrous metal can be carried out by gravity separation in the molten state, magnetic separation after cooling, or a combination thereof.

[0095] Gravity separation in the molten state utilizes the density difference between iron metal and sodium titanate, and since the iron metal sinks to the bottom and the titanate is located at the top at high temperatures, separation is possible.

[0096] Magnetic separation after cooling is a method of selectively separating iron metals using magnets by utilizing the ferromagnetism of iron metals at room temperature.

[0097] According to the method of the present invention, an iron removal rate of 95% or more, preferably 99% or more, in titanium concentrate can be achieved. The iron removal rate (η) is calculated by the following formula:

[0098] η(%) = [(w_Fe,Ti conc. - w_Fe,residue) / w_Fe,Ti conc.] × 100

[0099] Here, w_Fe,Ti conc. is the weight of iron in the raw concentrate, and w_Fe,residue is the weight of iron in the residue.

[0100] The recovered iron metal is in the form of an ingot, and SEM / EDS analysis shows that it is in the form of an Fe-C alloy. The recovered iron metal ingot can be recycled as a raw material for the steelmaking process.

[0102] The present invention also provides a roasting composition for recovering iron from titanium concentrate comprising titanium concentrate containing TiO₂ and Fe2O3; a sodium salt; and a carbonaceous reducing agent, wherein the weight ratio of titanium concentrate:sodium salt:carbonaceous reducing agent is 1:0.5 to 2.0:0.05 to 0.4.

[0103] In the above composition, the sodium salt is preferably Na2CO3, and the weight ratio of titanium concentrate:Na2CO3:carbonaceous reducing agent is preferably 1:0.8~1.5:0.05~0.3, most preferably 1:1:0.1.

[0105] The present invention also provides an iron metal ingot recovered by the above method. The recovered iron metal ingot can be used as a raw material for an ironmaking process.

[0106] The present invention also provides a use for the residue from which iron has been removed by the above method as a raw material for manufacturing high-purity titanium dioxide.

[0108] Hereinafter, preferred embodiments are presented to aid in understanding the present invention; however, the following embodiments are merely illustrative of the invention and the scope of the invention is not limited to the following embodiments.

[0110] <Example>

[0111] 1. Compositional Analysis of Titanium Concentrate from the Mianshan Formation

[0112] Low-grade titanium concentrate extracted from the Myeonsan Formation titanium ore was crushed and used in the experiment. The chemical composition of the concentrate was analyzed by ICP-OES (Inductively Coupled Plasma-Optical Emission Spectrometry), and the results are shown in Table 1.

[0113]

[0114] XRD analysis of low-grade cotton oxide titanium concentrate (Fig. 3) revealed peaks of TiO₂ (PDF #00-004-0551), Fe2O3 (PDF #00-024-0072), and SiO₂ (PDF #00-046-1045).

[0116] 2. Iron recovery through the soda roasting process

[0117] The above-mentioned low-grade cotton oxide titanium concentrate, Na2CO3, and graphite powder were mixed in the mixing ratios shown in Table 2 below. The mixture was loaded into a graphite crucible, covered with a graphite lid, and installed in an alumina reactor (see Fig. 4). After replacing the inside of the reactor with argon gas, the temperature was raised to 1600K and heat-treated for 5 to 10 hours. After heat treatment, the mixture was cooled to room temperature and the product was recovered.

[0118]

[0119] The iron ingots and residue were separated from the recovered product and weighed, and the composition of the residue was analyzed by ICP-OES. The iron removal rate was calculated using the following formula:

[0120] Iron Removal Rate (%) = [(Weight of Fe in Concentrate - Weight of Fe in Residue) / Weight of Fe in Concentrate] × 100

[0121] The results are shown in Table 3 below.

[0122]

[0123] Figure 5 shows a photograph of the recovered iron metal ingot. Referring to Table 3 and Figure 5 above, iron was recovered in the form of an ingot under most experimental conditions, but under the condition where an excess amount of carbon was used under the 1:1 ratio of concentrate to Na2CO3 (Experiment No. 250902, concentrate:C = 1:0.3), the iron did not aggregate into a complete ingot form.

[0124] As a result of analyzing the cross-section of the recovered iron ingot using SEM / EDS (Fig. 6), it was confirmed that Fe and C were the main components and that an Fe-C alloy was formed. As the carbon content increased, the carbon content inside the ingot also increased.

[0125] XRD analysis results of soda roasting residue (Fig. 8), Na4Ti8O 12Peaks such as (PDF #00-037-0273), Na2SiO3 (PDF #00-016-0818), and Na2Si2O5 (PDF #00-018-1242) were observed, confirming that the soda formation of TiO2 and SiO2 proceeded well.

[0126] Through the embodiments of the present invention, the effectiveness of the method for recovering iron using a soda roasting process from low-grade cotton oxide titanium concentrate was confirmed. As a result of comprehensively analyzing the results of the embodiments, the best iron recovery efficiency was achieved when the mixing ratio of titanium concentrate, sodium carbonate, and carbon was 1:1:0.1 (weight ratio), the reaction temperature was 1600K, the reaction time was 5 hours, and the argon atmosphere was argon atmosphere.

[0127] Under conditions of 10% carbon, an iron removal rate of over 99% was achieved and iron in the form of a complete ingot could be recovered, whereas under conditions of 30% carbon, an excessive amount of carbon hindered the aggregation of iron metal, resulting in a sharp decrease in the iron removal rate. This was visually confirmed through the photograph in Fig. 5 and the SEM / EDS analysis in Fig. 6, and it is interpreted that as the carbon content in the Fe-C alloy increases, the fluidity and aggregation of the droplets decrease.

[0128] Although varying the amount of sodium carbonate used from 100% to 200% did not significantly affect the iron removal rate, the XRD analysis results in Fig. 7 confirmed that the excess sodium carbonate did not participate in the reaction and volatilized. Therefore, considering economic feasibility, a weight ratio of 1:1 relative to the concentrate is deemed the most appropriate. This is further supported by the XRD analysis in Fig. 8, which showed that the residues under the Na2CO3 100% and 200% conditions had almost identical phase compositions.

[0129] When the reaction time was extended from 5 hours to 10 hours, the iron removal rate improved slightly from 99.57% to 99.75%, but the difference was negligible, so it was determined that 5 hours is sufficient when considering process efficiency. This is interpreted to be because both the reduction reaction of iron oxide and the soda reaction of titanium proceed rapidly at a high temperature of 1600K.

[0130] The results of the characteristic analysis of the soda roasting residue also demonstrated the superiority of the present invention. In the XRD analysis of Fig. 8, the TiO₂ peak of the raw concentrate completely disappeared, and sodium titanate (Na4Ti5O 12 The strong appearance of peaks for (Na2TiO3, etc.) indicates that the soda conversion of TiO₂ was successfully completed. In addition, the observation of peaks for sodium silicate (Na2SiO₃, Na2Si2O₅) shows that SiO₂, a gangue component, was also soda converted into a form that can be easily removed by subsequent water leaching.

[0131] As a result of analyzing the characteristics of the recovered iron ingot, it was confirmed to be an Fe-C alloy with approximately 82–83 wt% Fe and 17–18 wt% C, which is a form that can be recycled as a raw material for the steelmaking process due to its composition similar to cast iron. This implies that the present invention is an eco-friendly process that contributes to a circular economy in that it recovers iron as a useful metal resource rather than simply removing and discarding it.

[0132] In summary, the soda roasting process of the present invention has been experimentally proven to be an innovative technology that overcomes the limitations of existing wet processes, in that it recovers iron from low-grade cotton oxide titanium concentrate with a high efficiency of over 99%, obtains the recovered iron in the form of recyclable ingots, and the residue from which iron has been removed serves as an excellent raw material for the manufacture of high-grade titanium compounds. In particular, it is evaluated as having high potential for commercial application in that it achieves high process efficiency while solving environmental problems such as the use of large amounts of acid and the generation of acidic waste liquid.

[0134] Although specific embodiments regarding the method for recovering iron from titanium concentrate according to the present invention have been described so far, it is obvious that various modifications are possible within the scope of the present invention.

[0135] Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims set forth below as well as equivalents thereof.

[0136] That is, the aforementioned embodiments should be understood as exemplary in all respects and not limiting, and the scope of the invention is defined by the claims set forth below rather than by the detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the invention.

Claims

Claim 1 (a) a step of mixing a sodium salt and a carbonaceous reducing agent with titanium concentrate containing hematite (Fe2O3) and containing a total of 10% by weight of silica (SiO2) and alumina (Al2O3), wherein the titanium concentrate and the carbonaceous reducing agent are mixed in a weight ratio of 1:0.05 to less than 0.3; (b) a step of heat-treating the mixture at a temperature of 1400K or higher to reduce the hematite in the concentrate by agglomerating it into an iron metal ingot through carbon reduction and converting the TiO2 in the concentrate into sodium titanate; and (c) a step of recovering the agglomerated iron metal ingot; comprising a method for recovering iron from titanium concentrate. Claim 2 A method according to claim 1, wherein the titanium concentrate is a concentrate comprising 10 to 40 wt% of TiO2 and 40 to 70 wt% of Fe2O3. Claim 3 A method according to claim 1, wherein the titanium concentrate is a cotton acid layer titanium concentrate. Claim 4 A method according to claim 1, wherein the sodium salt is sodium carbonate (Na2CO3), sodium sulfate (Na2SO4), caustic soda (NaOH), or a mixture thereof. Claim 5 A method according to claim 1, wherein the sodium salt is a mixture of titanium concentrate and sodium salt in a weight ratio of 1:0.5 to 2.

0. Claim 6 delete Claim 7 A method according to claim 5, wherein the sodium salt is sodium carbonate (Na2CO3) and is mixed in a weight ratio of 0.8 to 3 relative to titanium concentrate. Claim 8 A method according to claim 1, wherein the heat treatment temperature is 1400 to 1800K. Claim 9 A method according to claim 1, wherein the heat treatment is performed for 3 to 15 hours. Claim 10 A method according to claim 1, wherein the heat treatment is performed in an inert atmosphere. Claim 11 A method according to claim 1, wherein the recovery of the ferrous metal in step (c) is performed by gravity separation in a molten state, magnetic separation after cooling, or a combination thereof. Claim 12 A method according to claim 1, wherein the recovered iron metal is in the form of an ingot, and the iron removal rate of the titanium concentrate is 95% or more. Claim 13 A method according to claim 1, further comprising, after step (c), step (d) of leaching the residue from which iron has been removed to produce a high-quality titanium compound. Claim 14 A roasting composition for recovering iron from titanium concentrate, comprising titanium concentrate containing TiO2 and Fe2O3 and containing a total of 10 weight% or more of silica (SiO2) and alumina (Al2O3); a sodium salt; and a carbonaceous reducing agent; wherein the weight ratio of titanium concentrate : sodium salt : carbonaceous reducing agent is 1 : 0.5~2.0 : 0.05~0.

3. Claim 15 A composition according to claim 14, wherein the sodium salt is Na2CO3, and the weight ratio of titanium concentrate : Na2CO3 : carbonaceous reducing agent is 1 : 0.8~1.5 : 0.05~0.

2. Claim 16 Iron metal ingot recovered by the method of paragraph 1. Claim 17 A method of using iron metal ingots recovered by the method of claim 1 as raw materials for an ironmaking process. Claim 18 A raw material composition for manufacturing titanium dioxide, comprising a residue containing sodium titanate from which iron has been removed by the method of claim 1.

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