A method for improving and classifying ilmenite

Abstract

The present invention discloses a method for upgrading and grading ilmenite, comprising the following steps: (1) treating the ilmenite by magnetic separation and flotation to obtain ilmenite concentrate; the process can adopt conventional methods in the prior art; (2) mixing a first solution with the ilmenite concentrate, slurrying, and then performing high-gradient magnetic separation to obtain magnetic concentrate slurry and magnetic tailings slurry, filtering them separately to obtain magnetic concentrate and magnetic tailings, and combining the filtrates; (3) using the magnetic concentrate for chloride titanium dioxide or sponge titanium production, and using the magnetic tailings for sulfuric acid titanium dioxide production to obtain by-products such as green vitriol and waste acid; the first solution in step (2) is obtained by dissolving the by-product green vitriol in step (3). The method for upgrading and grading ilmenite of the present invention utilizes green vitriol, a low-value by-product of sulfuric acid titanium dioxide production, to strengthen the slurrying and high-gradient magnetic separation processes of the ilmenite, thereby achieving efficient upgrading of the ilmenite concentrate, recycling of by-products, and high resource utilization.

Description

Technical Field

[0001] The invention belongs to the field of ore metallurgy, and in particular relates to a method for processing titanium ore. Background Art

[0002] Titanium dioxide is an important chemical raw material, widely used in industries and fields such as coatings, papermaking, ceramics, inks, rubber, food, catalysts, and cosmetics. Its consumption is considered a barometer of national economic development. Currently, titanium dioxide production processes are divided into two types: sulfuric acid and chlorination. The sulfuric acid method has low raw material quality requirements and wide adaptability, but it requires a long production process, consumes a lot of energy, generates large amounts of "three wastes", and pollutes the environment. The resulting titanium dioxide has high impurity content, low whiteness, and low product quality. The chlorination method has a shorter production process, is easy to scale up and operate continuously, produces less waste, and produces titanium dioxide with lower impurity content and higher whiteness. Its quality and value are superior to those produced by the sulfuric acid method, making it a direction encouraged for the development of titanium dioxide.

[0003] my country has the world's largest titanium ore reserves, but 98% of it consists of ilmenite with high calcium, magnesium, and silicon contents, distributed in the Panzhihua region. A combined high-gradient magnetic separation and flotation recovery process can be used to produce titanium concentrate with a TiO2 grade of approximately 47%. However, due to the high levels of calcium, magnesium, and silicon impurities, this concentrate cannot be used as a feedstock for chloride-based titanium dioxide and sponge titanium production, which primarily relies on sulfuric acid treatment to produce titanium dioxide. my country relies heavily on imports for high-quality titanium ore used in chloride-based titanium dioxide and sponge titanium production, maintaining a high degree of foreign dependence. Both sponge and chloride-based titanium dioxide production require high-quality titanium-rich feedstock. Generally, to ensure stable operation of the fluidized bed chlorination furnace, the grade and impurity requirements for this feedstock are as follows: a TiO2 grade exceeding 90%, a CaO content below 0.3%, a combined CaO and MgO content below 1.5%, a SiO2 content below 1.5%, and at least 80% particle size greater than 100μm. my country's large amount of ilmenite cannot meet the above requirements. How to use my country's abundant ilmenite resources to produce titanium-rich materials for the chloride process is an urgent need to solve problems such as my country's excessive dependence on foreign high-quality titanium ores and to promote the transformation and upgrading of the titanium industry. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a method for upgrading and grading ilmenite, which can utilize my country's abundant ilmenite resources to produce titanium-rich materials for the chlorination process and realize the recycling of by-products, with high resource utilization rate.

[0005] In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0006] A method for upgrading and classifying ilmenite, comprising the following steps:

[0007] (1) ilmenite is subjected to a combined treatment of magnetic separation and flotation to obtain titanium concentrate; this process can adopt conventional methods in the prior art;

[0008] (2) mixing the first solution with the titanium concentrate, slurrying, and then performing high gradient magnetic separation to obtain magnetic concentrate slurry and magnetic tailings slurry, filtering them separately to obtain magnetic concentrate and magnetic tailings, and combining the filtrates;

[0009] (3) Using the magnetic concentrate for the production of titanium dioxide or sponge titanium by the chloride process, and using the magnetic tailings for the production of titanium dioxide by the sulfate process, to obtain by-products such as green vitriol and waste acid;

[0010] The first solution in step (2) is obtained by dissolving the by-product green vitriol in step (3).

[0011] In the above-mentioned method for upgrading and classifying ilmenite, preferably, the first solution in step (2) is also partially derived from the filtrate obtained by combining in step (2).

[0012] In the above-mentioned method for upgrading and classifying ilmenite, preferably, the filtrate obtained by combining in step (2) is reduced by adding iron flakes or iron powder, and the by-product waste acid obtained in step (3) is used to adjust the pH value to 3-4.

[0013] In the above-mentioned method for upgrading and grading ilmenite, preferably, the by-product green vitriol in step (3) is dissolved to obtain a green vitriol solution, and the by-product waste acid obtained in step (3) is used to adjust the pH value to 3-4, and the mass concentration of the green vitriol solution is controlled to be 45-55%. The green vitriol solution is first mixed with the titanium concentrate to perform a mixing and slurrying, and then the filtrate obtained by combining in step (2) is added to perform a second mixing and slurrying.

[0014] In the above-mentioned method for upgrading and classifying ilmenite, preferably, during the one-time mixing and slurrying, the slurrying temperature is controlled to be 45-60° C. and the slurrying time is 0.5-1 h.

[0015] In the above-mentioned method for upgrading and classifying ilmenite, preferably, during the secondary mixing and slurrying, the mass concentration of the titanium concentrate in the slurry is controlled to be 25-35%, the mass concentration of the green vitriol solution is controlled to be 32-38%, and the slurrying temperature is room temperature.

[0016] In the above-mentioned method for upgrading and classifying ilmenite, preferably, during high gradient magnetic separation, a vertical ring pulsating high gradient magnetic separator is used for magnetic separation, and the magnetic separation conditions are a magnetic field strength of 0.4-1.2T, a magnetic medium size of 1-4mm, and a pulsating intensity of 100-400r / min.

[0017] In the above-mentioned method for upgrading and classifying ilmenite, preferably, the magnetic concentrate is subjected to redox modification and acid leaching to obtain artificial rutile, which is then used in the production of titanium dioxide or sponge titanium by the chloride process.

[0018] In the above-mentioned method for upgrading and classifying ilmenite, preferably, the redox modification is to oxidize the magnetic concentrate at 800-1000°C for 0.5-1.5h, and then reduce it in an atmosphere furnace using coal gas at 700-900°C for 0.5-1.5h.

[0019] In the above-mentioned method for upgrading and classifying ilmenite, preferably, during acid leaching, hydrochloric acid is used for leaching at normal pressure, the mass concentration of hydrochloric acid is 20-30%, the liquid-solid ratio during leaching is (1-5) mL:1 g, and the leaching time is 4-6 h.

[0020] In the above-mentioned method for upgrading and classifying ilmenite, preferably, the ilmenite comes from the Panzhihua area and is ilmenite with high calcium, magnesium and silicon contents.

[0021] The method for utilizing ilmenite to improve the quality and grade the utilization of the present invention is to prepare a solution of a certain mass concentration of green vitriol, a low-value byproduct of titanium dioxide produced by the sulfuric acid process (3-4 tons of green vitriol, a byproduct of one ton of titanium dioxide produced by the sulfuric acid process), and to mix the solution with the ilmenite to form a slurry with a certain solid mass concentration. The prepared slurry is treated with a high-gradient magnetic separator to obtain a slurry of magnetic concentrate and magnetic tailings. The magnetic concentrate and magnetic tailings slurry are concentrated and filtered to obtain magnetic concentrate, magnetic tailings and filtrate. After the filtrate is recovered, iron powder or iron sheets are added for reduction to prevent the oxidation of divalent iron to trivalent iron, which causes corrosion of the magnetic separation equipment. A small amount of waste acid produced by the sulfuric acid process is added to the reduced filtrate to adjust the pH to between 3 and 4 for stabilization. Finally, the filtrate is re-slurried with the titanium concentrate and subsequently sorted, thereby realizing the recycling of most of the green vitriol solution and the recycling of the waste acid.

[0022] The magnetic concentrate obtained by the above method has a high TiO2 grade and low impurities such as CaO and SiO2, while the magnetic tailings have a relatively low TiO2 grade and high impurities such as CaO and SiO2. The magnetic concentrate is modified through redox treatment to convert the TiO2 in the ilmenite into a rutile network structure. The modified titanium concentrate is leached with hydrochloric acid to produce artificial rutile with a TiO2 grade exceeding 92% and a CaO content below 0.3%, meeting the requirements of large-scale fluidized bed chlorination furnaces. This can then be chlorinated to produce chloride-based titanium dioxide or sponge titanium. The magnetic tailings are then used to produce titanium dioxide using the traditional sulfuric acid process, producing byproducts such as green vitriol and waste acid, which can be used in the aforementioned slurry adjustment and high-gradient magnetic separation processes.

[0023] The method for utilizing the quality improvement and classification of ilmenite of the present invention innovatively adopts the low-value by-product green vitriol of sulfuric acid process titanium dioxide production to strengthen the slurry adjustment and high-gradient magnetic separation process of ilmenite. On the one hand, in the slurry adjustment stage, the green vitriol solution has a certain analytical effect on the flotation agent participating in the flotation agent on the surface of the ilmenite, and can further enhance the dispersion of the ilmenite particles, creating good conditions for the subsequent high-gradient magnetic separation to improve the quality and separate silicate minerals; on the other hand, in the high-gradient magnetic separation stage, the green vitriol solution can further improve the selectivity of ilmenite separation, realize the efficient quality improvement of titanium concentrate, and finally obtain magnetic separation concentrate with high TiO2 grade and low impurity content and magnetic separation tailings with relatively low TiO2 grade.

[0024] The present invention recycles the filtrate and reuses it in the slurry adjustment and high gradient magnetic separation process of ilmenite. Since the filter cake in the magnetic concentrate and magnetic tailings filtration process has a certain water content, it will take away a part of the green vitriol solution. This part of the green vitriol solution needs to be replenished, and the replenishment source is still the green vitriol, a by-product of the sulfuric acid process titanium dioxide production. Based on the above process and our research findings, the present invention also optimizes the slurry adjustment stage. First, a high concentration of green vitriol solution (45-55%) is mixed with the titanium concentrate, and a stirring slurry adjustment process is carried out at a higher temperature (45-60°C). This process uses a high concentration of green vitriol solution (45-55%) to mix with the titanium concentrate. The green vitriol solution is used to analyze the flotation agent on the surface of ilmenite at a higher temperature, which can improve the analysis effect. Compared with mixing green vitriol with the filtrate and then slurrying (the concentration of the green vitriol solution is low at this time), the analysis effect will be better; after one slurrying, the recovered filtrate is added to the slurry after the first slurrying, and the concentrations of green vitriol and titanium concentrate in the slurry are regulated to ensure that the concentrations of the green vitriol solution and the titanium concentrate in the magnetic separation process are within a suitable range (a high concentration of the green vitriol solution is not conducive to magnetic separation), ensuring the efficient subsequent high-gradient magnetic separation, and the secondary slurrying can be carried out at room temperature. The present invention achieves the purpose of supplementing green vitriol through secondary slurrying, enhances the analysis effect of the green vitriol solution, and realizes the concentration control of the green vitriol solution, achieving the purpose of killing two birds with one stone.

[0025] In the above-mentioned magnetic separation concentrate, TiO Grade can reach more than 50%, its CaO and SiO Content ratio is CaO and SiO in the concentrate that obtains by methods such as conventional gravity separation, magnetic separation and flotation Etc. impurity content is low, and TiO in the concentrate Recovery rate can be high by about 20% (conventional method concentrate TiO Recovery rate is about 40%, TiO in the inventive method concentrate Recovery rate can reach more than 60%), and the indexes such as upgrading titanium concentrate quality and productivity are all better.The magnetic separation concentrate can obtain TiO after chemical modification and hydrochloric acid leaching Content is higher than 94%, CaO content is lower than 0.15%, SiO Content is lower than 1.5% the high-quality artificial rutile that meets the chlorination process and is used, and rutile quality and output are all higher, and granularity keeps the titanium concentrate ore granularity, satisfies the large-scale boiling chlorination furnace raw material requirement.

[0026] Green vitriol solution is used for slurry adjustment and high gradient magnetic separation of Panxi titanium flotation concentrate. During the slurry adjustment stage, green vitriol solution has a certain analytical effect on the flotation agents participating in the ilmenite surface, and can further enhance the dispersion of ilmenite particles, creating good conditions for subsequent high gradient magnetic separation to improve the quality and separate silicate minerals; in the high gradient magnetic separation stage, green vitriol solution can further improve the selectivity of ilmenite separation, thereby achieving efficient quality improvement of titanium concentrate. The invention utilizes a low-value byproduct of sulfuric acid titanium dioxide production, green vitriol, to enhance the high-gradient magnetic separation of Panxi titanium concentrate to produce a magnetic concentrate with high TiO2 grade and low impurity content. The TiO2 grade can reach over 60%, and the CaO and SiO2 contents are lower than those of impurities such as CaO and SiO2 in concentrates obtained by conventional gravity separation, magnetic separation, and flotation. Furthermore, the TiO2 recovery rate in the concentrate can be increased by approximately 20% (compared to the TiO2 recovery rate of about 40% in conventional concentrates, which can reach over 60% in concentrates obtained by the invention). This improves the quality and yield of the upgraded titanium concentrate. Chemical modification and hydrochloric acid leaching of the magnetic concentrate yields high-quality synthetic rutile with a TiO2 content exceeding 94%, a CaO content below 0.15%, and a SiO2 content below 1.5%, suitable for use in the chloride process. The rutile has higher quality and yield, and its particle size maintains that of the original titanium concentrate, meeting the raw material requirements of large-scale fluidized bed chlorination furnaces.

[0027] The green vitriol solution used in the enhanced ilmenite slurry adjustment and high-gradient magnetic separation of the present invention comes from green vitriol, a low-value by-product of titanium dioxide production by the sulfuric acid process, and the acid used for filtrate stabilization also comes from the waste acid produced by titanium dioxide production by the sulfuric acid process. There is basically no need to purchase other materials or reagents, the cost required for quality improvement is low, and most of the green vitriol solution is recycled through a simple filtration process without external discharge, which is environmentally friendly.

[0028] Compared with the prior art, the advantages of the present invention are:

[0029] 1. The method for upgrading and grading ilmenite of the present invention utilizes high-gradient magnetic separation to treat titanium concentrate to obtain magnetic concentrate with high TiO2 grade and low impurity content and magnetic tailings with relatively low TiO2 grade and high impurity content such as CaO and SiO2. The magnetic concentrate and magnetic tailings are respectively suitable for the production of titanium dioxide by the chlorination process and the sulfuric acid process, and the graded utilization of ilmenite can be achieved. This method can utilize my country's abundant ilmenite resources to produce titanium-rich materials for the chlorination process, solve the problem of my country's high dependence on foreign high-quality titanium ores, and both high-grade and low-grade titanium ores are utilized, with a high overall recovery rate of titanium ore.

[0030] 2. The method for utilizing ilmenite for upgrading and grading of the present invention utilizes green vitriol, a low-value by-product of titanium dioxide production by the sulfuric acid process, to strengthen the slurry mixing and high-gradient magnetic separation processes of the ilmenite. The green vitriol can enhance the dispersion of the ilmenite in the slurry mixing process and improve the selectivity of ilmenite separation in the high-gradient magnetic separation process, thereby realizing efficient upgrading of the titanium concentrate. Moreover, green vitriol comes from green vitriol, a low-value by-product of titanium dioxide production by the sulfuric acid process, and basically no additional materials or reagents need to be purchased. The cost required for upgrading is low, the recycling of by-products is realized, and the resource utilization rate is high. Moreover, most of the green vitriol solution is recycled through a simple filtration process without external discharge, which is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 The present invention is a process flow chart of the method for upgrading and classifying ilmenite. DETAILED DESCRIPTION

[0033] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0034] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0035] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0036] The major impurity minerals in the Panxi titanium flotation concentrate used in the following examples and comparative examples are silicate minerals. Mg is partially present in the ilmenite and partially in the silicate minerals, which can be effectively removed by hydrochloric acid leaching. CaO and SiO2 are primarily present in the silicate minerals, and some of the dissolved CaO and SiO2 cannot be removed by hydrochloric acid leaching. This results in the artificial rutile obtained after direct modification and leaching of the Panxi titanium concentrate having high CaO and SiO2 contents, and the TiO2 grade rarely reaching above 90%, making it difficult to use as a raw material for large-scale fluidized bed chlorination furnaces and thus unable to produce titanium dioxide or sponge titanium. However, after the treatment steps of the present invention, the minerals that are difficult to remove by hydrochloric acid leaching are mainly transferred to the magnetic separation tailings, which can reduce the CaO and SiO2 contents in the magnetic separation concentrate.

[0037] Example 1:

[0038] like Figure 1 As shown, this embodiment uses a method for upgrading and classifying ilmenite, which includes the following steps:

[0039] The TiO2 grade of a certain titanium concentrate in Panxi (ilmenite is obtained by combined treatment of magnetic separation and flotation, which is the existing technology) is 45.88%, and the contents of impurities CaO, SiO2 and MgO are 2.33%, 2.88% and 4.03% respectively. The ore was mixed with a 36% mass concentration of a byproduct of Panxi sulfuric acid titanium dioxide production, a solution of green vitriol (which can be obtained by supplementing the filtrate after the previous round of magnetic separation with a low-value byproduct of green vitriol from sulfuric acid titanium dioxide production) at room temperature to form a slurry with a solid mass concentration of 32.45%. Magnetic separation was performed using a vertical ring pulsating high-gradient magnetic separator under the conditions of a magnetic field intensity of 0.65T, a magnetic medium size of 2mm, and a pulsation intensity of 300r / min. After a roughing and a concentrating separation process, a magnetic concentrate slurry was obtained. The roughing tailings slurry and the concentrating tailings slurry were combined to obtain a magnetic tailings slurry. The magnetic concentrate slurry and the magnetic tailings slurry were filtered separately to obtain a magnetic concentrate, magnetic tailings, and filtrate. A small amount of iron powder was added to the filtrate, and green vitriol was added. After that, an appropriate amount of acid was added to adjust the pH to 3-4. The filtrate was then used to mix the ore with the titanium concentrate ore and then carried out a next round of magnetic fluid coupled high-gradient magnetic separation.

[0040] The sorting indicators are shown in Table 1 below, where the TiO2 grade and recovery rate in the magnetic separation concentrate are 50.35% and 63.28% respectively, and the CaO, SiO2 and MgO contents are 0.25%, 0.60% and 1.66% respectively; the TiO2 grade and recovery rate in the magnetic separation tailings are 39.79% and 36.72% respectively, and the CaO, SiO2 and MgO contents are 5.16%, 5.98% and 7.26% respectively.

[0041] Table 1: High gradient magnetic separation index

[0042] product Yield / % <![CDATA[TiO2 grade]]> <![CDATA[TiO2 recovery rate]]> CaO grade <![CDATA[SiO2 grade]]> MgO grade Magnetic concentrate 57.66 50.35 63.28 0.25 0.6 1.66 Magnetic separation tailings 42.34 39.79 36.72 5.16 5.98 7.26 Feed 100.00 45.88 100.00 2.33 2.88 4.03

[0043] The resulting magnetically separated concentrate was oxidized in a roaster at 950°C for 1 hour, then reduced in an atmosphere furnace at 850°C for 1 hour using coal gas to produce a modified titanium concentrate. The modified titanium concentrate was then leached at atmospheric pressure using hydrochloric acid at a concentration of 25% and a liquid-to-solid ratio of 3.0:1 (mL:g) for 5 hours. After leaching, the residue was filtered, washed 2-3 times with water, placed in a drying oven, dried at 150°C, and cooled to produce artificial rutile. The artificial rutile contained 95.45% TiO2, 0.12% CaO, 1.45% SiO2, and 0.94% MgO, respectively, making it suitable for use as a raw material for boiling chlorination. The magnetically separated tailings were produced using a conventional sulfuric acid process for titanium dioxide, yielding byproducts of chlorite and waste acid. The chlorite was used in the slurry preparation of the Panxi titanium concentrate, and the waste acid was used for pH adjustment.

[0044] Example 2:

[0045] The raw ore of this embodiment is the same as that of Example 1. In the slurry adjustment stage, the green vitriol, a by-product of titanium dioxide production by the sulfuric acid process, is first dissolved to obtain a green vitriol solution with a mass concentration of 48%. The pH value is adjusted to 3-4 using the waste acid by-product of titanium dioxide production by the sulfuric acid process. The high-concentration green vitriol solution is mixed with the titanium concentrate and slurry is adjusted at 50°C for 40 minutes. The filtrate obtained by filtration after the previous round of magnetic separation (pH value is 3-4) is then added and mixed and slurried for the second time at room temperature. Finally, the mass concentration of the green vitriol solution is 36%, and the concentration of the titanium concentrate is 32.45%. Then, magnetic separation is carried out according to the magnetic separation conditions in the aforementioned Example 1.

[0046] The sorting indicators are shown in Table 2 below, where the TiO2 grade and recovery rate in the magnetic concentrate are 51.31% and 63.73% respectively, and the CaO, SiO2 and MgO contents are 0.24%, 0.58% and 1.62% respectively; the TiO2 grade and recovery rate in the magnetic tailings are 41.37% and 36.27% respectively, and the CaO, SiO2 and MgO contents are 4.76%, 4.93% and 7.08% respectively.

[0047] Table 2: High gradient magnetic separation index

[0048] product Yield / % <![CDATA[TiO2 grade]]> <![CDATA[TiO2 recovery rate]]> CaO grade <![CDATA[SiO2 grade]]> MgO grade Magnetic concentrate 58.62 51.31 63.73 0.24 0.58 1.62 Magnetic separation tailings 41.38 41.37 36.27 4.76 4.93 7.08 Feed 100.00 47.20 100.00 2.11 2.38 3.88

[0049] The resulting magnetically separated concentrate was oxidized in a roaster at 950°C for 1 hour, then reduced in an atmosphere furnace at 850°C for 1 hour using coal gas to produce a modified titanium concentrate. The modified titanium concentrate was then leached at atmospheric pressure using hydrochloric acid at a concentration of 25% and a liquid-to-solid ratio of 3.0:1 (mL:g) for 5 hours. After leaching, the residue was filtered, washed 2-3 times with water, placed in a drying oven, dried at 150°C, and cooled to produce artificial rutile. The artificial rutile contained 97.55% TiO2, 0.10% CaO, 1.06% SiO2, and 0.68% MgO, respectively, making it suitable for use as a raw material for boiling chlorination. The magnetically separated tailings were produced using a conventional sulfuric acid process for titanium dioxide, yielding byproducts of chlorite and waste acid. The chlorite was used in the slurry preparation of the Panxi titanium concentrate, and the waste acid was used for pH adjustment.

[0050] Example 3:

[0051] like Figure 1 As shown, this embodiment uses a method for upgrading and classifying ilmenite, which includes the following steps:

[0052] The TiO2 grade of a titanium concentrate in Panxi (ilmenite is obtained by combined treatment of magnetic separation and flotation, which is the existing technology) is 40.23%, and the contents of impurities CaO, SiO2 and MgO are 4.45%, 5.76% and 4.63% respectively. The solution is mixed with a green vitriol solution (a byproduct of the production of titanium dioxide by sulfuric acid process in Panxi) with a pH value of 3-4 and a mass concentration of 36% (which can be obtained by supplementing the low-value green vitriol of the production of titanium dioxide by sulfuric acid process with the filtrate after the previous round of magnetic separation, or from the filtrate in Example 1) at room temperature to form a slurry with a solid mass concentration of 32%. A vertical ring pulsating high gradient magnetic separator is used for magnetic separation. The magnetic separation conditions are a magnetic field intensity of 0.60T, a magnetic medium size of 1mm, and a pulsation intensity of 250r / min. After a roughing and a concentrating separation process, a magnetic concentrate slurry is obtained. The roughing tailings slurry and the concentrating tailings slurry are combined to obtain a magnetic tailings slurry. The magnetic concentrate slurry and the magnetic tailings slurry are filtered separately to obtain a magnetic concentrate, a magnetic tailings, and a filtrate. A small amount of iron powder is added to the filtrate for stirring, green vitriol is added, and then an appropriate amount of acid is added to adjust the pH to 3-4, and then used for slurrying with the titanium concentrate ore and carrying out the next round of magnetic fluid coupled high gradient magnetic separation.

[0053] The sorting indicators are shown in Table 3 below, where the TiO2 grade and recovery rate in the magnetic separation concentrate are 50.31% and 58.52% respectively, and the CaO, SiO2 and MgO contents are 0.26%, 0.56% and 1.46% respectively; the TiO2 grade and recovery rate in the magnetic separation tailings are 31.37% and 41.48% respectively, and the CaO, SiO2 and MgO contents are 8.13%, 10.33% and 7.42% respectively.

[0054] Table 3: High gradient magnetic separation index

[0055] product Yield <![CDATA[TiO2 grade]]> <![CDATA[TiO2 recovery rate]]> CaO grade <![CDATA[SiO2 grade]]> MgO grade Magnetic concentrate 46.80 50.31 58.52 0.26 0.56 1.46 Magnetic separation tailings 53.20 31.37 41.48 8.13 10.33 7.42 Feed 100.00 40.23 100.00 4.45 5.76 4.63

[0056] The resulting magnetically separated concentrate was oxidized in a roaster at 900°C for 1.5 hours, then reduced in an atmosphere furnace at 870°C for 1 hour using coal gas to produce a modified titanium concentrate. The modified titanium concentrate was then leached at atmospheric pressure using hydrochloric acid at a concentration of 30% and a liquid-to-solid ratio of 3.5:1 (mL:g) for 4 hours. After leaching, the residue was filtered, washed 2-3 times with water, dried in a drying oven at 150°C, and cooled to produce artificial rutile. The artificial rutile contained 96.65% TiO2, 0.10% CaO, 1.49% SiO2, and 0.77% MgO, respectively, making it suitable for use as a raw material for boiling chlorination. The magnetically separated tailings were produced using a conventional sulfuric acid process for titanium dioxide, yielding byproducts of chlorite and waste acid. The chlorite was used in the slurry preparation of the Panxi titanium concentrate, and the waste acid was used for pH adjustment.

Claims

1. A method for upgrading and classifying ilmenite, characterized in that: The following steps are involved: (1) ilmenite is treated by magnetic separation and flotation to obtain titanium concentrate; (2) mixing the first solution with the titanium concentrate, slurrying, and then performing high gradient magnetic separation to obtain magnetic concentrate slurry and magnetic tailings slurry, filtering them separately to obtain magnetic concentrate and magnetic tailings, and combining the filtrates; (3) Using the magnetic concentrate for the production of titanium dioxide or sponge titanium by the chloride process, and using the magnetic tailings for the production of titanium dioxide by the sulfate process, to obtain by-products such as green vitriol and waste acid; The first solution in step (2) is obtained by dissolving the by-product green vitriol in step (3).

2. The method for upgrading and classifying ilmenite according to claim 1, characterized in that: The first solution in step (2) is also partially derived from the filtrate obtained by combining in step (2).

3. The method for upgrading and classifying ilmenite according to claim 2, wherein: The filtrate obtained by combining in step (2) is reduced by adding iron flakes or iron powder, and the by-product waste acid obtained in step (3) is used to adjust the pH value to 3-4.

4. The method for upgrading and classifying ilmenite according to claim 2, wherein: The by-product green vitriol in step (3) is dissolved to obtain a green vitriol solution, and the by-product waste acid obtained in step (3) is used to adjust the pH value to 3-4, and the mass concentration of the green vitriol solution is controlled to be 45-55%. The green vitriol solution is first mixed with titanium concentrate to perform a mixing and slurrying, and then the filtrate obtained by combining in step (2) is added to perform a second mixing and slurrying.

5. The method for upgrading and classifying ilmenite according to claim 4, characterized in that: When mixing and slurrying once, the slurrying temperature is controlled to be 45-60℃ and the slurrying time is 0.5-1h.

6. The method for upgrading and classifying ilmenite according to claim 4, characterized in that: During the secondary mixing and slurry adjustment, the mass concentration of the titanium concentrate in the slurry is controlled to be 25-35%, the mass concentration of the green vitriol solution is controlled to be 32-38%, and the slurry adjustment temperature is room temperature.

7. The method for upgrading and classifying ilmenite according to any one of claims 1 to 6, characterized in that: During high gradient magnetic separation, a vertical ring pulsating high gradient magnetic separator is used for magnetic separation. The magnetic separation conditions are as follows: magnetic field strength of 0.4-1.2T, magnetic medium size of 1-4mm, and pulsating intensity of 100-400r / min.

8. The method for upgrading and classifying ilmenite according to any one of claims 1 to 6, characterized in that: The magnetic concentrate is subjected to redox modification and acid leaching to obtain artificial rutile, which is then used in the production of titanium dioxide or sponge titanium by the chloride process.

9. The method for upgrading and classifying ilmenite according to claim 8, characterized in that: The redox modification is to oxidize the magnetic concentrate at 800-1000°C for 0.5-1.5h, and then reduce it in an atmosphere furnace at 700-900°C using coal gas for 0.5-1.5h.

10. The method for upgrading and classifying ilmenite according to claim 8, characterized in that: During acid leaching, hydrochloric acid is used for leaching at normal pressure, the mass concentration of hydrochloric acid is 20-30%, the liquid-solid ratio during leaching is (1-5) mL:1 g, and the leaching time is 4-6 hours.

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