A method for preparing chlorination feedstock using high-calcium-magnesium ilmenite and the chlorination feedstock

Abstract

This invention relates to the field of metallurgical technology, specifically to a method for preparing chlorination feedstock using high-calcium magnesium ilmenite and the chlorination feedstock itself. The method comprises: (a) mixing high-calcium magnesium ilmenite with a reducing agent and then smelting to obtain molten titanium slag; adding a magnesium additive to the molten titanium slag to obtain magnesium-modified molten titanium slag; the magnesium additive includes at least one of magnesium oxide, magnesium carbonate, magnesium sulfate, magnesium chloride, or magnesium nitrate; and (b) cooling, crushing, pre-acid leaching, and pressurized acid leaching of the magnesium-modified molten titanium slag. This method improves the acid solubility of the titanium slag using a magnesium additive, effectively removing impurity ions during the subsequent pressurized acid leaching process; it is adaptable to titanium feedstocks with high calcium and magnesium impurity content; the operation is simple, and it yields chlorination feedstocks with CaO content ≤0.1 wt.% and CaO+MgO content ≤1.5 wt.%.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and more specifically, to a method for preparing chlorination raw materials using high-calcium magnesium ilmenite and the chlorination raw materials themselves. Background Technology

[0002] The titanium industry chain has two distinct branches: the titanium materials industry and the titanium dioxide industry. In the titanium materials industry, starting with the mining and beneficiation of ilmenite and rutile, sponge titanium is produced and then alloyed with titanium. This titanium alloy is widely used in aerospace, chemical, and shipbuilding industries. Titanium metal is hailed as a "modern metal" and a "strategic metal," an indispensable raw material for modern industry and cutting-edge technology, and a high-tech raw material urgently needed by my country's strategic emerging industries. In the titanium dioxide industry, starting with the mining and beneficiation of ilmenite and rutile, titanium dioxide, a chemical intermediate, is produced through physical and chemical methods. It is widely used in basic industries such as coatings, plastics, papermaking, inks, and chemical fibers, and its consumption level is considered a barometer of the national economy.

[0003] In the titanium industry chain, titanium tetrachloride is an intermediate product for the preparation of sponge titanium and titanium dioxide by the chloride process. Due to its unique production process, it has extremely stringent requirements for titanium-rich raw materials, requiring a titanium grade greater than 85 wt.% and low impurity content (CaO≤0.15 wt.%, CaO+MgO≤1.5 wt.%). It is heavily reliant on imports and urgently needs to break through the technology for preparing titanium-rich chloride materials.

[0004] The Panxi region of my country possesses abundant titanium ore resources, but its high gangue content and poor beneficiation properties necessitate deep grinding and beneficiation. The resulting concentrates are low in grade, high in impurities, particularly calcium and magnesium, and have a fine particle size. While direct acid leaching or pretreatment followed by acid leaching can yield titanium-rich materials with compositions meeting the requirements for fluidized bed chlorination, the particle size falls far short of these requirements. Therefore, enhancing the utilization value of low-grade titanium resources and processing them into high-quality titanium dioxide or sponge titanium raw materials is of great significance.

[0005] Domestic and international research on the utilization of this portion of titanium resources mainly focuses on two directions: the combined method of electric arc furnace smelting of titanium concentrate and upgrading with titanium slag, and the direct upgrading of titanium concentrate to synthetic rutile. Among these, the direct upgrading of titanium concentrate to synthetic rutile is relatively simple, but suffers from severe issues with product particle size. The combined electric arc furnace smelting and titanium slag upgrading method can effectively solve the problem of finer product particle size, but it faces challenges such as high process difficulty and high cost. Given these research shortcomings, it is essential to develop a method that ensures product particle size and utilizes high-calcium-magnesium ilmenite in a short-process manner to produce fluidized bed chlorination feedstock.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] One aspect of the present invention relates to a method for preparing chlorination feedstock using high-calcium magnesium ilmenite, comprising the following steps:

[0008] (a) High-calcium magnesium ilmenite and a reducing agent are mixed and smelted to obtain molten titanium slag material; magnesium additive is added to the molten titanium slag material to obtain magnesium-modified molten titanium slag material;

[0009] The magnesium additive includes at least one of magnesium oxide, magnesium carbonate, magnesium sulfate, magnesium chloride, or magnesium nitrate.

[0010] (b) The magnesium-modified molten titanium slag material is cooled, crushed, pre-acid-leached and pressurized acid-leached to obtain the chlorinated raw material.

[0011] The method for preparing chlorination raw materials using high-calcium-magnesium ilmenite is characterized by complete reaction, low requirements for ilmenite raw materials, lenient conditions for calcium and magnesium impurity content, simple operation, short process flow, low production energy consumption, and easy industrialization.

[0012] Another aspect of the present invention relates to the chlorination feedstock obtained by the method for preparing chlorination feedstock using high-calcium magnesium ilmenite.

[0013] The chlorination raw material has high titanium grade, low impurity content, and qualified particle size, which can meet the requirements for the production of titanium dioxide by the chlorination process.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] (1) The method for preparing chlorinated raw materials using high-calcium magnesium ilmenite provided by the present invention uses magnesium additives to modify titanium slag. The magnesium additives are added in the molten state of titanium slag and react with MgTi2O5 at high temperature to generate MgTiO3 compounds that are easily soluble in acid, which effectively improves the acid solubility of titanium slag and allows impurity ions to be effectively removed in the later pressure acid leaching process. The reaction under this high temperature condition is a liquid-liquid reaction, with better contact effect and more complete reaction.

[0016] (2) The method for preparing chlorination raw materials using high-calcium magnesium ilmenite provided by the present invention has low requirements for ilmenite raw materials and is lenient in terms of calcium and magnesium impurity content. It is suitable for titanium raw materials with high calcium and magnesium impurity content and can obtain high-quality chlorination raw materials with TiO2 content ≥90wt.%, CaO≤0.1wt.%, CaO+MgO≤1.5wt.%, and suitable particle size. The method is simple to operate, has a short process flow, eliminates the oxidation-reduction process, reduces production energy consumption, and is easy to realize industrial production.

[0017] (3) The chlorination raw material provided by the present invention has high titanium grade, low impurity content, and particle size that can meet the requirements for the production of titanium dioxide by the chlorination process. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0019] One aspect of the present invention relates to a method for preparing chlorination feedstock using high-calcium magnesium ilmenite, comprising the following steps:

[0020] (a) High-calcium magnesium ilmenite and a reducing agent are mixed and smelted to obtain molten titanium slag material; magnesium additive is added to the molten titanium slag material to obtain magnesium-modified molten titanium slag material;

[0021] The magnesium additive includes at least one of magnesium oxide, magnesium carbonate, magnesium sulfate, magnesium chloride, or magnesium nitrate.

[0022] (b) The magnesium-modified molten titanium slag material is cooled, crushed, pre-acid-leached and pressurized acid-leached to obtain the chlorinated raw material.

[0023] The main components of ilmenite are TiO2 and FeO, with the remainder being SiO2, CaO, MgO, Al2O3, and V2O5. This invention first involves high-temperature reduction smelting of the ilmenite. The ilmenite is heated and melted, and the Fe oxides in the ilmenite are reduced to metallic iron, which precipitates. Titanium dioxide, along with impurities such as calcium oxide, magnesium oxide, aluminum oxide, and silicon dioxide, enters the slag phase and ultimately separates from the iron. Through high-temperature smelting, most of the iron is removed, and titanium is enriched.

[0024] This invention is the first to add 10wt.%-50wt.% magnesium additive to molten titanium slag. The MgTi2O5 in the molten titanium slag reacts with magnesium to form easily acid-soluble MgTiO3 compounds, effectively improving the acid solubility of impurities in the titanium slag, especially magnesium impurities. This modification method, combined with acid leaching, can remove impurity elements in one step through pressurized acid leaching, eliminating the need for conventional oxidation and reduction processes. Simultaneously, the introduction of magnesium adjusts the binary basicity of the slag, improving its fluidity and facilitating the smooth operation of subsequent water quenching processes. In contrast, existing technologies that disclose alkali melting modification or smelting with alkali modification only utilize alkali to destroy the black titanium stone and glassy phase structure in the titanium slag to improve acid solubility. Further oxidation-reduction is required to improve the acid leaching effect on impurity elements, and the use of alkalis such as soda ash, caustic soda, and sodium bicarbonate introduces new impurity elements, increasing the pressure of subsequent water treatment. Compared to existing technologies, this invention is simpler and more effective.

[0025] The chlorination raw materials mentioned in this invention include those used in the preparation of titanium dioxide by the chlorination process.

[0026] Preferably, the magnesium additive is calculated as Mg, the high-calcium magnesium ilmenite is calculated as Ti, and the molar ratio of Mg to Ti is 0.5 to 3:1 (e.g., 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1 or 3:1).

[0027] Preferably, in the high-calcium magnesium ilmenite, the content of TiO2 is ≥46 wt.%, the content of CaO is ≥0.2 wt.%, and the content of MgO is ≥2.0 wt.%.

[0028] Preferably, the mass of the reducing agent is 10% to 50 wt.% (e.g., 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%) of the mass of the high-calcium magnesium ilmenite.

[0029] Preferably, the reducing agent comprises coal and / or coke.

[0030] Preferably, the smelting temperature is 1350–1650°C (e.g., 1350°C, 1380°C, 1400°C, 1430°C, 1450°C, 1480°C, 1500°C, 1530°C, 1550°C, 1580°C, 1600°C, 1630°C, or 1650°C).

[0031] Preferably, the particle size of the crushed material is 20 mesh to 160 mesh (e.g., 20 mesh, 30 mesh, 40 mesh, 50 mesh, 60 mesh, 70 mesh, 80 mesh, 90 mesh, 110 mesh, 120 mesh, 130 mesh, 140 mesh, 150 mesh or 160 mesh).

[0032] Preferably, the mass concentration of the acid solution used for pre-acid leaching is 10% to 30% (e.g., 10%, 15%, 20%, 25%, or 30%).

[0033] Preferably, the liquid-to-solid ratio of the pre-acid leaching is (1-6):1m 3 / t (e.g., 1:1m) 3 / t、2:1m 3 / t、3:1m 3 / t、4:1m 3 / t、5:1m 3 / t or 6:1m 3 / t).

[0034] Preferably, the pre-acid leaching temperature is 20–100°C (e.g., 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, or 100°C).

[0035] Preferably, the pre-acid soaking time is 0.5 to 4 hours (e.g., 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours or 4 hours).

[0036] Preferably, the acid solution used for pre-acid leaching includes at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid, or hydrofluoric acid.

[0037] Preferably, the mass concentration of the acid solution used for pressurized pickling is 10% to 30% (e.g., 10%, 15%, 20%, 25%, or 30%).

[0038] Preferably, the temperature of the pressurized acid leaching is 120-170°C (e.g., 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C or 170°C).

[0039] Preferably, the pressure of the pressurized acid leaching is 0.2 to 0.9 MPa (e.g., 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa, 0.6 MPa, 0.7 MPa, 0.8 MPa or 0.9 MPa).

[0040] Preferably, the pressurized acid leaching time is 0.5 to 6 hours (e.g., 0.5 hours, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours).

[0041] Preferably, the acid solution used for pressurized acid leaching includes at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid, or hydrofluoric acid.

[0042] Preferably, the cooling method includes water quenching.

[0043] Preferably, the water quenching solution includes water.

[0044] This invention employs water quenching for cooling. The resulting rapidly cooled modified water-quenched slag exhibits poor crystallinity, with each phase "frozen" before crystallization. Compared to normal titanium slag, due to the modification with magnesium additives, the water-quenched slag contains a lower content of insoluble impurities, leading to better impurity leaching during subsequent acid leaching. Compared to traditional air cooling, water quenching allows for control of slag particle size by adjusting water pressure, maintaining most materials between 20 and 160 mesh, significantly improving crushing efficiency and reducing production costs.

[0045] Since some metallic iron inevitably remains in the modified water-quenched slag after reduction smelting, direct pressure acid leaching will produce a lot of H2, which is not conducive to safe production. Therefore, a certain proportion of acid is used to pre-leach the modified water-quenched slag before pressure acid leaching. A temperature higher than room temperature and lower than the boiling point of the acid solution is more conducive to the dissolution of metallic iron. Therefore, the reaction temperature is selected as 20-100℃.

[0046] The pre-acid-leached titanium slag is directly transferred to a pressure vessel for pressure acid leaching reaction. Due to the modification of magnesium additives, the acid solubility of impurities in the modified water-quenched slag is effectively improved. Impurity elements such as Mg, Al, and Ca will separate from the titanium slag and enter the solution. After conventional water washing and drying, titanium-rich raw materials that meet the requirements of boiling chlorination can be obtained.

[0047] This invention solves the problem that the fine particle size of the product cannot meet the requirements for use in boiling chlorination by adopting a process flow of smelting, water quenching and cooling, and crushing.

[0048] This invention eliminates the oxidation, reduction, calcination and desiliconization processes. By modifying titanium slag with magnesium additives, impurity elements can be removed to within acceptable ranges in a single pressurized acid leaching. Furthermore, this method has good applicability to the impurity element content in raw materials and is more suitable for Panzhihua high-calcium magnesium ore.

[0049] This invention eliminates the processes of ball milling, pelletizing, preheating, reduction nitriding, crushing and screening. The process is simple and easy to implement in industrialization, with low equipment requirements and low production costs. It also avoids the problems of fine powder generated by crushing and low titanium yield.

[0050] This invention eliminates the need for additional additives or binders in the pelletizing process, and the calcination can be carried out in an air atmosphere, making the process simple and conducive to industrial production.

[0051] Compared with existing technologies, the method used in this invention has lower requirements for raw materials, a wider range of applications, and can be smelted using traditional industrial electric furnaces, thus requiring less equipment.

[0052] Compared with existing technologies, the process route of this invention omits steps such as magnetic separation, flotation, roasting, and magnetic separation, resulting in a shorter process flow, simpler equipment, and avoiding the impact of magnetic separation and crushing on titanium yield.

[0053] Compared to existing technologies, magnesium additives effectively combine with titanium, improving the acid solubility of the titanium slag itself. In addition, the subsequent water quenching cooling method prevents impurity elements from fully crystallizing with the titanium solid solution, allowing them to be removed in a single acid leaching process. This eliminates the need for oxidation and reduction processes, and provides broader requirements for raw material indicators, making it more suitable for Panzhihua high-calcium magnesium titanium ore.

[0054] The modification of magnesium additives has an excellent effect on the leaching of impurities, eliminating the need for subsequent acid leaching to remove calcium, redox acid leaching to remove magnesium, calcination and other processes. Raw materials that meet the requirements for boiling chlorination can be obtained in one acid leaching step.

[0055] Preferably, the pressurized acid leaching process further includes water washing and drying.

[0056] Preferably, the moisture content of the dried chlorinated raw material is ≤0.5 wt.%.

[0057] Another aspect of the present invention relates to the chlorination feedstock obtained by the method for preparing chlorination feedstock using high-calcium magnesium ilmenite.

[0058] The chlorination raw material has high titanium grade, low impurity content, and qualified particle size, which can meet the requirements for the production of titanium dioxide by the chlorination process.

[0059] The embodiments of the present invention will now be described in detail with reference to specific examples and comparative examples.

[0060] Example 1

[0061] The method for preparing chlorination feedstock using high-calcium magnesium ilmenite provided in this embodiment includes the following steps:

[0062] 1. Take the sorted high-calcium magnesium titanium concentrate and 10% coal reducing agent by weight of raw materials, smelt at 1550℃ for 1 hour to obtain molten titanium slag material, in which the high-calcium magnesium titanium concentrate has TiO2 content of 48.37wt.%, CaO content of 0.57wt.%, and MgO content of 3.16wt.%.

[0063] 2. Transfer the molten titanium slag material to a transfer electric furnace, heat it to the smelting temperature and add MgO at the same time. The magnesium additive is calculated as Mg, the high-calcium magnesium ilmenite is calculated as Ti, and the molar ratio of Mg to Ti is 0.5:1 to obtain magnesium-modified molten titanium slag material.

[0064] 3. The magnesium-modified molten titanium slag material is rapidly cooled by water quenching and crushed to a qualified particle size to obtain modified water-quenched slag;

[0065] 4. The obtained modified water-quenched slag is pre-acid-leached using hydrochloric acid with a concentration of 18 wt.% and a liquid-to-solid ratio of 6:1m. 3 / t, at a temperature of 100℃, pre-acid-leached material was obtained for 0.5h;

[0066] 5. The pre-acid-leached material is subjected to pressure acid leaching using hydrochloric acid with a concentration of 20 wt.% and a liquid-to-solid ratio of 6:1m. 3 / t, temperature 155℃, time 0.5h, water washing, drying at 100℃ for 2.5h, to obtain chlorination raw material with qualified particle size, TiO2 content 91.52wt.%, CaO content 0.088wt.%, MgO content 1.37wt.%.

[0067] Example 2

[0068] The method for preparing chlorination feedstock using high-calcium magnesium ilmenite provided in this embodiment includes the following steps:

[0069] 1. Take the sorted high-calcium magnesium titanium concentrate and 20% coke reducing agent by weight of raw materials, smelt at 1600℃ for 3h to obtain molten titanium slag material, in which the high-calcium magnesium titanium concentrate has TiO2 content of 48.08wt.%, CaO content of 0.36wt.%, and MgO content of 3.85wt.%;

[0070] 2. Transfer the molten titanium slag material to a transfer electric furnace, heat it to the smelting temperature and add MgCO3 at the same time. The magnesium additive is calculated as Mg, the high-calcium magnesium ilmenite is calculated as Ti, and the molar ratio of Mg to Ti is 3:1 to obtain magnesium-modified molten titanium slag material.

[0071] 3. The magnesium-modified molten titanium slag material is rapidly cooled by water quenching and crushed to a qualified particle size to obtain modified water-quenched slag;

[0072] 4. The obtained modified water-quenched slag is pre-acid-leached using hydrochloric acid with a concentration of 20 wt.% and a liquid-to-solid ratio of 4:1m. 3 / t, at a temperature of 80℃, pre-acid-leached material is obtained, and the pre-acid-leaching time is 1h;

[0073] 5. The pre-acid-leached material is subjected to pressure acid leaching using hydrochloric acid with a concentration of 25 wt.% and a liquid-to-solid ratio of 5:1m. 3 / t, temperature 135℃, time 5h, water washing, drying at 80℃ for 3h to obtain chlorination raw material with qualified particle size, TiO2 content 91.8wt.%, CaO content 0.076wt.%, MgO content 1.28wt.%.

[0074] Example 3

[0075] The method for preparing chlorination feedstock using high-calcium magnesium ilmenite provided in this embodiment includes the following steps:

[0076] 1. Take the sorted high-calcium magnesium titanium concentrate and 30% coal reducing agent by weight of raw materials, smelt at 1400℃ for 2.5h to obtain molten titanium slag material, in which the high-calcium magnesium titanium concentrate has TiO2 content of 48.29wt.%, CaO content of 0.33wt.%, and MgO content of 3.73wt.%;

[0077] 2. Transfer the molten titanium slag material to a transfer electric furnace, heat it to the smelting temperature and add MgO at the same time. The magnesium additive is calculated as Mg, the high-calcium magnesium ilmenite is calculated as Ti, and the molar ratio of Mg to Ti is 1:1 to obtain magnesium-modified molten titanium slag material.

[0078] 3. The magnesium-modified molten titanium slag material is rapidly cooled by water quenching and crushed to a qualified particle size to obtain modified water-quenched slag;

[0079] 4. The obtained modified water-quenched slag is pre-acid-leached using HCl solution with a concentration of 23 wt.% and a liquid-to-solid ratio of 1:1. 3 / t, at a temperature of 20℃, pre-acid-leached material is obtained, and the pre-acid-leaching time is 4h;

[0080] 5. The pre-acid-leached material is subjected to pressure acid leaching using HCl solution with a concentration of 26 wt.% and a liquid-to-solid ratio of 3:1m. 3 / t, temperature 150℃, time 1.5h, water washing, drying at 130℃ for 1.5h to obtain chlorination raw material with qualified particle size, TiO2 content 91.76wt.%, CaO content 0.08wt.%, MgO content 1.38wt.%.

[0081] Example 4

[0082] The method for preparing chlorination feedstock using high-calcium magnesium ilmenite provided in this embodiment includes the following steps:

[0083] 1. Take the sorted high-calcium magnesium reduced titanium concentrate and 40% coke reducing agent by weight of raw materials, smelt at 1500℃ for 1.5h to obtain molten titanium slag material, in which the high-calcium magnesium titanium reduced titanium concentrate has TiO2 content of 49.05wt.%, CaO content of 0.45wt.%, and MgO content of 2.95wt.%.

[0084] 2. Transfer the molten titanium slag material to a transfer electric furnace, heat it to the smelting temperature and add MgCO3 at the same time. The magnesium additive is calculated as Mg, the high-calcium magnesium ilmenite is calculated as Ti, and the titanium molar ratio of Mg to Ti is 2:1 to obtain magnesium-modified molten titanium slag material.

[0085] 3. The magnesium-modified molten titanium slag material is rapidly cooled by water quenching and crushed to a qualified particle size to obtain modified water-quenched slag;

[0086] 4. The obtained modified water-quenched slag is pre-acid-leached using hydrochloric acid solution with a concentration of 15 wt.% and a liquid-to-solid ratio of 3:1m. 3 / t, at a temperature of 70℃, pre-acid-leached material is obtained, and the pre-acid-leaching time is 2h;

[0087] 5. The pre-acid-leached material is subjected to pressure acid leaching using hydrochloric acid solution with a concentration of 25 wt.% and a liquid-to-solid ratio of 5:1m. 3 / t, temperature 145℃, time 2h, water washing, drying at 150℃ for 1h to obtain chlorination raw material with qualified particle size, TiO2 content 91.54wt.%, CaO content 0.084wt.%, MgO content 1.41wt.%.

[0088] Example 5

[0089] The method for preparing chlorination feedstock using high-calcium magnesium ilmenite provided in this embodiment includes the following steps:

[0090] 1. Take the sorted high-calcium magnesium reduced vanadium-titanium iron concentrate and 50% coal reducing agent by weight of raw materials, smelt at 1450℃ for 2 hours to obtain molten titanium slag material, in which the high-calcium magnesium reduced vanadium-titanium iron concentrate has TiO2 content of 49.41wt.%, CaO content of 0.21wt.%, and MgO content of 2.04wt.%.

[0091] 2. Transfer the molten titanium slag material to a transfer electric furnace, heat it to the smelting temperature and add MgCO3 at the same time. The magnesium additive is calculated as Mg, the high-calcium magnesium ilmenite is calculated as Ti, and the molar ratio of Mg to Ti is 1.5:1 to obtain magnesium-modified molten titanium slag material.

[0092] 3. The magnesium-modified molten titanium slag material is rapidly cooled by water quenching and crushed to a qualified particle size to obtain modified water-quenched slag;

[0093] 4. The modified water-quenched slag is pre-acid-leached using hydrochloric acid solution with a concentration of 10 wt.% and a liquid-to-solid ratio of 2:1 at 50°C to obtain pre-acid-leached material for 3 hours.

[0094] 5. The pre-acid-leached material is subjected to pressure acid leaching with hydrochloric acid solution at a concentration of 22 wt.%, a liquid-to-solid ratio of 4:1, a temperature of 140℃, and a time of 3.5 h. After washing with water and drying at 110℃ for 2 h, a chlorinated raw material with qualified particle size is obtained, containing 92.63 wt.% TiO2, 0.09 wt.% CaO, and 1.23 wt.% MgO.

[0095] Comparative Example 1

[0096] The only difference between this comparative example and Example 1 is that MgO in step 2 is replaced with sodium carbonate.

[0097] Comparative Example 2

[0098] The only difference between this comparative example and Example 1 is that MgO in step 2 is replaced with potassium carbonate.

[0099] Comparative Example 3

[0100] The only difference between this comparative example and Example 1 is that MgO was not added in step 2.

[0101] The elements of the chlorination feedstocks prepared in the examples and comparative examples were analyzed, and the results are shown in Table 1.

[0102] Table 1

[0103]

[0104] The data in Table 1 show that the titanium grade of the material with added magnesium carbonate is higher and the content of calcium and magnesium impurities is lower. This is because during the smelting process, the magnesium additive reacts with MgTi2O5 to generate MgTiO3 compounds that are easily soluble in acid, which effectively improves the acid solubility of titanium slag. This allows impurity ions to be effectively removed during the later pressurized acid leaching process. Therefore, it is easier to separate impurity elements from titanium elements in the later acid leaching stage, resulting in a better acid leaching effect. Simply adding sodium carbonate or potassium carbonate only reduces the calcium content to below 0.1 wt.% after acid leaching, and the magnesium removal effect is not good. This is because calcium in water-quenched slag exists as CaSi2O5, which is easily soluble in acid and can be removed by acid leaching.

[0105] Although the present invention has been illustrated and described with specific embodiments, it should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; those skilled in the art should understand that modifications can be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein, without departing from the spirit and scope of the present invention; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention; therefore, this means that all such substitutions and modifications that fall within the scope of the present invention are included in the appended claims.

Claims

1. A method for preparing chlorination feedstock using high-calcium-magnesium ilmenite, characterized in that, Includes the following steps: (a) High-calcium magnesium ilmenite and reducing agent are mixed and smelted to obtain molten titanium slag material; magnesium additive is added to the molten titanium slag material to obtain magnesium-modified molten titanium slag material; MgTi2O5 in the molten titanium slag reacts with magnesium element to generate MgTiO3 compound that is easily soluble in acid; The magnesium additive includes at least one of magnesium oxide, magnesium carbonate, magnesium sulfate, magnesium chloride, or magnesium nitrate. The magnesium additive is calculated as Mg, and the high-calcium magnesium ilmenite is calculated as Ti, with a molar ratio of Mg to Ti of 0.5 to 3:1; The reducing agent has a mass of 10% to 50% of the mass of the high-calcium magnesium ilmenite; The reducing agent includes coal and / or coke; The smelting temperature is 1350~1650℃; (b) Cooling, crushing, pre-acid leaching, and pressurized acid leaching of the magnesium-modified molten titanium slag material to obtain the chlorinated raw material; The cooling method is water quenching.

2. The method for preparing chlorination feedstock using high-calcium magnesium ilmenite according to claim 1, characterized in that, The high-calcium magnesium ilmenite contains TiO2 content ≥ 46 wt.%, CaO content ≥ 0.2 wt.%, and MgO content ≥ 2.0 wt.%.

3. The method for preparing chlorination feedstock using high-calcium magnesium ilmenite according to claim 1, characterized in that, The particle size of the crushed material is 20 mesh to 160 mesh.

4. The method for preparing chlorination feedstock using high-calcium magnesium ilmenite according to claim 1, characterized in that, The mass concentration of the acid solution used for pre-acid leaching is 10% to 30%. The liquid-to-solid ratio of the pre-acid leaching is (1~6):1m 3 / t; The temperature for the pre-acid leaching is 20~100℃; The pre-acid leaching time is 0.5~4 hours; The acid solution used for pre-acid leaching includes at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid, or hydrofluoric acid.

5. The method for preparing chlorination feedstock using high-calcium magnesium ilmenite according to claim 1, characterized in that, The mass concentration of the acid solution used in the pressurized pickling process is 10% to 30%. The temperature of the pressurized acid leaching is 120~170℃; The pressure of the pressurized acid leaching is 0.2~0.9 MPa; The pressurized acid leaching time is 0.5~6 hours; The acid solution used for pressurized acid leaching includes at least one of hydrochloric acid, nitric acid, acetic acid, sulfuric acid, or hydrofluoric acid.

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