A method for recovering iron and titanium from vanadium extraction slag by hydrogen-based reduction-magnetic separation

Abstract

The present application belongs to the technical field of metallurgical engineering, and specifically discloses a method for separating and recovering iron and titanium from vanadium extraction slag by hydrogen-based reduction-magnetic separation, which comprises the following steps: preparing green balls by finely grinding, acid leaching, concentrating, filtering and high-pressure roller grinding sodiumized vanadium extraction slag; obtaining reduced pellets containing elemental iron and titanium oxide by hydrogen-based direct reduction of the green balls in a hydrogen-based vertical furnace with an oxidizing roasting and a heating device combined with heat pipe heat exchange and electromagnetic induction; and obtaining reduced iron powder and high-titanium slag by crushing, ball milling, fine grinding and magnetic separation of the reduced pellets. The present application successfully solves the problem of powdering of sodiumized vanadium extraction slag pellets of vanadium-titanium magnetite, and realizes efficient separation and recovery of iron and titanium in vanadium extraction slag by using a hydrogen-based vertical furnace to reduce the vanadium extraction slag, thereby eliminating the environmental pollution problem caused by the storage of vanadium extraction slag and providing good conditions for the popularization and application of the sodiumized roasting wet process for efficient vanadium extraction. Meanwhile, the present application has an important demonstration effect on the popularization and application of hydrogen metallurgical process.

Description

Technical Field

[0001] This invention relates to the field of metallurgical engineering technology, specifically to a method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation. Background Technology

[0002] Currently, sodium vanadium extraction is one of the most effective methods for extracting vanadium from vanadium-titanium magnetite, offering high vanadium recovery rates and a simple process. However, there are few industrial production lines in China that perform sodium vanadium extraction from vanadium-titanium magnetite concentrate, primarily because the sodium vanadium extraction slag is difficult to utilize, as the iron and titanium within it are difficult to effectively separate and recover. The vanadium extraction slag contains abundant titanium and iron resources, with its mineral composition mainly consisting of ilmenite and magnetite, typically with a TiO2 grade of 5–15% and a TFe grade of 30–65%.

[0003] Currently, the main methods for recovering titanium and iron from vanadium extraction slag are the blast furnace method or the pre-reduction-smelting method. This involves pelletizing the vanadium extraction slag, pre-reducing it, and then separating the titanium and iron through electric furnace smelting. However, because vanadium extraction slag contains a large amount of alkali metals, the pre-reduction process causes severe pellet pulverization, significantly worsening the permeability of the material during subsequent smelting and increasing smelting energy consumption. Furthermore, the titanium in the titanium-containing slag after smelting exists primarily in the form of pyroxene and perovskite, making economical recovery difficult. The severe reduction expansion and pulverization of vanadium extraction slag pellets also render them unsuitable for blast furnace ironmaking, resulting in a titanium resource recovery rate of generally less than 60% in China. In contrast, vanadium extraction slag abroad is mainly dumped, causing not only serious resource waste but also secondary environmental pollution. Moreover, under my country's "dual carbon" background, both the blast furnace method and the pre-reduction-smelting method have problems such as high energy consumption and high CO2 emissions. For example, the smelting temperature of electric furnace ironmaking in China is generally 1500-1800℃, the energy consumption of the blast furnace process is about 300-500 kgce / t, and the power consumption of the electric furnace smelting process is about 300-350 kWh / t.

[0004] To address the aforementioned issues, Chinese patent (patent application number: CN201310035277.3) discloses a method for separating and recovering valuable substances from vanadium extraction slag using superconducting high-gradient magnetic separation technology. This method involves recovering valuable elements from sodium-treated vanadium extraction slag using a superconducting high-gradient magnetic field, achieving a Fe2O3 content of up to 56% in the recovered material. This method primarily targets iron extraction from vanadium extraction slag through magnetic separation and does not address the recovery of titanium resources from the slag.

[0005] Chinese patent (patent application number: CN201811276342.0) discloses a method for recovering vanadium from vanadium extraction tailings through calcification. This method involves secondary calcification and roasting of the vanadium extraction tailings, followed by sulfuric acid leaching of vanadium, achieving a vanadium transfer leaching rate of over 60%. This method primarily targets secondary vanadium extraction from vanadium extraction tailings and does not address the recovery of titanium and iron resources from the calcified vanadium extraction tailings.

[0006] Meanwhile, Bi Xiurong, Liu Gang, et al. (Metallurgical Equipment, 2014(01):20-23) published an experimental study on the basic performance of sodium removal and iron extraction from vanadium slag, proposing two methods for treating vanadium slag through chlorination roasting-reduction-magnetic separation. After magnetic separation, the reduced iron powder product had a TFe content of 36.18%, a Na content of 1.95%, and an Fe recovery rate of 90.82%. This method does not involve the removal of impurities from the vanadium slag, and the pelletizing phenomenon is serious during reduction. It also does not involve the recovery of titanium resources.

[0007] Wu Enhui, Zhu Rong, et al. (Iron and Steel Vanadium Titanium, 2015, 36(05):40-46) published a paper on the molten reduction of carbon-containing pellets from vanadium extraction tailings in an electric arc furnace to extract iron, proposing a method for extracting titanium slag by molten reduction in an electric arc furnace, obtaining molten iron with an iron recovery rate of over 90%. This method does not involve the pre-reduction of vanadium extraction slag pellets, but rather the simultaneous reduction and molten separation of carbon-containing pellets from vanadium extraction tailings in the electric furnace. The molten titanium-containing slag is difficult to recover due to its low titanium content, and the electric furnace slag is not utilized.

[0008] Although sodium vanadium extraction is one of the most efficient methods for recovering vanadium from vanadium-titanium magnetite, none of the aforementioned methods address the problem of excessively high alkali metal or aluminosilicate impurities in the vanadium extraction slag. This leads to severe pulverization during the vanadium extraction slag pellet reduction process, poor titanium-iron separation, high product impurity content, and virtually no effective recovery of titanium resources. Furthermore, existing blast furnace methods or pre-reduction-melting methods suffer from high energy consumption and high CO2 emissions. Therefore, to achieve effective recovery of titanium and iron resources from vanadium extraction slag, there is an urgent need to develop an economical, low-energy-consumption, and environmentally friendly method for titanium-iron separation. Summary of the Invention

[0009] In view of the above-mentioned shortcomings, the present invention provides a method for separating and recovering iron and titanium from vanadium extraction slag by hydrogen-based reduction and magnetic separation. The present invention can solve the problems of severe reduction and pulverization of vanadium extraction slag pellets and poor separation effect of titanium and iron resources due to the high content of impurities such as alkali metals and aluminosilicates in vanadium extraction slag, as well as the problems of high energy consumption and high CO2 emissions in the extraction process.

[0010] To achieve the above objectives, the present invention provides a method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation, comprising the following steps:

[0011] S1. Vanadium-titanium magnetite concentrate is subjected to sodium vanadium extraction to obtain sodium vanadium extraction slag; the sodium vanadium extraction slag is finely ground to make its particle size of -0.074mm account for 70-80%, and its specific surface area is 1100-1500m². 2 / g;

[0012] S2. The finely ground vanadium-containing sodium leaching slag from S1 is subjected to acid leaching to obtain acid-leached slag. The acid-leached slag is then filtered, dewatered, and subsequently subjected to high-pressure roller milling to achieve a particle size of -0.074 mm (80-95%) and a specific surface area of ​​1700-2100 m². 2 / g;

[0013] S3. After mixing the material from the high-pressure roller mill in S2 with an organic composite binder, pelletize it to obtain green pellets with a particle size of 10-16mm; oxidize and calcine the green pellets to obtain vanadium extraction slag oxidized pellets with a compressive strength greater than 2500N / P.

[0014] S4. The hot vanadium-extraction slag oxide pellets after S3 oxidation roasting are directly reduced in a hydrogen-based vertical shaft furnace to obtain reduced pellets containing strongly magnetic elemental iron and non-magnetic titanium oxides. The hot vanadium-extraction slag oxide pellets are added from the top of the hydrogen-based vertical shaft furnace. The hydrogen-based gas in the furnace is first heated through external heat exchange tubes, then introduced through gas pipes surrounding the furnace cylinder at the bottom. A second heating and reforming process is then completed through an electromagnetic induction heat treatment device located on the lower side wall of the furnace cylinder. The hydrogen-based gas in the furnace is H2 or a mixture of H2 and CO. The temperature in the upper reduction zone of the furnace is 800–1000℃, the gas pressure is 0.2–0.5 MPa, and the reduction time is 60–150 min.

[0015] S5. The reduced pellets from S4 are crushed, ball-milled, finely ground, and then magnetically separated to obtain reduced iron powder and high-titanium slag.

[0016] According to one aspect of the present invention, in step S1, the TFe content in the sodium vanadium extraction slag is 48% to 62%, the TiO2 content in the sodium vanadium extraction slag is 5% to 15%, the alkali metal content in the sodium vanadium extraction slag is 1% to 3%, and the aluminosilicate content is greater than 7%.

[0017] According to one aspect of the present invention, in step S2, the acid used for acid leaching is composed of sulfuric acid and hydrofluoric acid, the mass ratio of sulfuric acid to hydrofluoric acid is 0 to 2, and the amount of acid used for acid leaching is 0.1 to 5.0 g / L.

[0018] According to one aspect of the present invention, in step S2, the acid leaching temperature is 60-90°C and the time is 30-150 min; the alkali metal content in the acid leaching residue is less than 0.29%, and the aluminosilicate content is less than 3%.

[0019] According to one aspect of the present invention, in step S2, the acid leaching residue needs to be precipitated and concentrated in a sedimentation tank before filtration. The concentrated acid leaching residue is then filtered and dewatered by a filter press or a disc vacuum filter. After dewatering, the material is subjected to a high-pressure roller mill.

[0020] According to one aspect of the present invention, in step S3, the organic composite adhesive is composed of sodium humate, starch and polyacrylamide; the mass ratio of sodium humate, starch and polyacrylamide is 1-3:3-1:0.05-0.2; and the amount of the organic composite adhesive is 0.1-0.8 wt%.

[0021] According to one aspect of the present invention, in step S3, the oxidative calcination includes three stages, namely a drying stage, a preheating stage, and a calcination stage; the temperature of the drying stage is 180-350°C, and the time is 4-10 min; the temperature of the preheating stage is 800-1100°C, and the time is 10-18 min; the temperature of the calcination stage is 1250-1380°C, and the time is 15-30 min.

[0022] According to one aspect of the present invention, in step S3, the compressive strength of the vanadium extraction slag oxide pellets is 2500-3000 N / P.

[0023] According to one aspect of the present invention, in step S4, the heating current frequency of the induction furnace is 100-800 Hz, the heat preservation temperature is 1000-1200°C, and the heat preservation time is 30-120 min.

[0024] According to one aspect of the present invention, in step S5, the proportion of particles finely ground to -0.074 mm is 35-50%; the magnetic field strength of the magnetic separation is 500 Gs to 2000 Gs.

[0025] The principle of this invention:

[0026] Firstly, utilizing the acid solubility of alkali metals, aluminosilicates, and calcium and magnesium oxides, impurities such as alkali metals, aluminosilicates, and calcium and magnesium oxides are removed through acid leaching. This avoids the severe pulverization problem caused by alkali metals during subsequent direct reduction of pellets, improves the titanium and iron content in the vanadium extraction slag, and weakens the adverse effects of aluminosilicates on the subsequent reduction process. Hydrogen-based direct reduction utilizes the stronger reducing power of hydrogen and the difference in reducing properties between iron oxides and titanium oxides, promoting the preferential reduction of more iron oxides to metallic iron. Simultaneously, leveraging the magnetic induction properties of metallic iron, iron grains are induced to gradually aggregate and grow under electromagnetic induction heating conditions, reducing the phenomenon of metallic iron and titanium oxide encapsulation, increasing the particle size difference between metallic iron and titanium oxides, and achieving the dissociation of iron and titanium monomers. Furthermore, electromagnetic induction heating of the lower reduction pellets increases the temperature of the reducing gas entering the furnace, promoting heating and reforming of the reducing gas, compensating for insufficient hydrogen reduction heat, and improving the reduction reaction in the upper and middle regions. Finally, by utilizing the magnetic differences between metallic iron and titanium oxide, efficient separation of reduced iron powder and high-titanium slag was achieved through grinding and magnetic separation, producing two products: reduced iron powder and high-titanium slag. This process also enabled the recovery of both titanium and iron resources.

[0027] The beneficial effects of this invention are:

[0028] (1) This invention removes impurities (mainly alkali metals, aluminosilicates and calcium and magnesium oxides) from finely ground sodium vanadium slag by acid leaching, thereby reducing the content of impurities such as sodium, silicon, aluminum, calcium and magnesium in sodium vanadium slag. This not only completely solves the problem of reduction and pulverization caused by excessive alkali metals in vanadium slag, but also improves the grade of iron and titanium in vanadium slag, which helps to achieve efficient reduction of vanadium slag pellets and separation of iron and titanium.

[0029] (2) This invention directly reduces the hot vanadium slag oxide pellets after oxidation roasting in a hydrogen-based vertical furnace, which can achieve a significant reduction in carbon dioxide emissions during the reduction process. At the same time, reduction and growth of metallic iron grains are achieved in the hydrogen-based vertical furnace, with reduction in the upper and middle regions and electromagnetic induction heat treatment in the lower region, which simplifies the process flow and reduces production costs.

[0030] (3) This invention reduces pellets by electromagnetic induction heat treatment, induces iron grain growth, and further improves the separation efficiency of titanium and iron; at the same time, by increasing the temperature of the lower metallized pellets, the heating and catalytic reforming effect of the reducing gas is improved, making up for the problem of insufficient heat of hydrogen reduction and accelerating the reduction reaction rate.

[0031] (4) The entire process of this invention does not involve high-temperature smelting and uses hydrogen-based reducing agents, which reduces energy consumption, achieves CO2 emission reduction in the reduction process, and enhances the reduction effect of vanadium slag.

[0032] (5) Compared with the traditional long process of blast furnace, the present invention is more economical, simpler in process, has a higher recycling rate of iron and titanium resources, less carbon dioxide emissions, iron recovery rate of more than 90% in the whole process, TiO2 content of high titanium slag is more than 70%, and titanium recovery rate is more than 90%. Attached Figure Description

[0033] Figure 1 This is a process flow diagram of the method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction and magnetic separation, as described in this invention. Detailed Implementation

[0034] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0035] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0036] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0037] To address the problem of excessively high alkali metal or aluminosilicate impurities in vanadium extraction slag in existing technologies, which leads to severe pulverization during the vanadium extraction slag pellet reduction process, poor titanium-iron separation, high product impurity content, and near-complete failure to recover titanium resources, this application provides a method for hydrogen-based reduction-magnetic separation and recovery of iron and titanium from vanadium extraction slag. The process flow diagram is shown below. Figure 1 As shown, it includes the following steps:

[0038] S1. Vanadium-titanium magnetite concentrate is subjected to sodium vanadium extraction to obtain sodium vanadium extraction slag; the sodium vanadium extraction slag is finely ground to make its particle size of -0.074mm account for 70-80%, and its specific surface area is 1100-1500m². 2 / g;

[0039] S2. The finely ground vanadium-containing sodium leaching slag from S1 is subjected to acid leaching to obtain acid-leached slag. The acid-leached slag is then filtered, dewatered, and subsequently subjected to high-pressure roller milling to achieve a particle size of -0.074 mm (80-95%) and a specific surface area of ​​1700-2100 m². 2 / g;

[0040] In step S2 of the present invention, acid leaching utilizes the characteristics that Na2O, sodium salts (sodium silicate, sodium aluminate), aluminosilicates and calcium salts are easily soluble in acid. Acid leaching reduces the Na2O content in the sodium vanadium extraction slag, avoids excessive Na2O content which would cause pellet reduction and pulverization, and is beneficial to improving the titanium and iron content in the sodium vanadium extraction slag.

[0041] In step S2 of the present invention, the purpose of high-pressure roller milling is to increase the specific surface area of ​​the material, which is beneficial to enhancing the sphericity and oxidation performance of the material.

[0042] S3. After mixing the material from the high-pressure roller mill in S2 with an organic composite binder, pelletize it to obtain green pellets with a particle size of 10-16mm; oxidize and calcine the green pellets to obtain vanadium extraction slag oxidized pellets with a compressive strength greater than 2500N / P.

[0043] In step S3 of the present invention, the oxidative roasting can be carried out on a chain grate machine-rotary kiln-ring cooler or a belt roaster.

[0044] S4. The hot vanadium-extraction slag oxide pellets after S3 oxidation roasting are directly reduced in a hydrogen-based vertical shaft furnace to obtain reduced pellets containing strongly magnetic elemental iron and non-magnetic titanium oxides. The hot vanadium-extraction slag oxide pellets are added from the top of the hydrogen-based vertical shaft furnace. The hydrogen-based gas in the furnace is first heated through external heat exchange tubes, then introduced through gas pipes surrounding the furnace cylinder at the bottom. A second heating and reforming process is then completed through an electromagnetic induction heat treatment device located on the lower side wall of the furnace cylinder. The hydrogen-based gas in the furnace is H2 or a mixture of H2 and CO. The temperature in the upper reduction zone of the furnace is 800–1000℃, the gas pressure is 0.2–0.5 MPa, and the reduction time is 60–150 min.

[0045] In step S4 of this invention, hydrogen-based gas enters the furnace from the lower part of the vertical shaft furnace along the gas supply pipe of the ring furnace, flows upward through the metallized pellet bed, and the oxide pellets are added from the top of the furnace and move downward under gravity in a counter-current motion. The reducing gas in the lower part of the vertical shaft furnace is reformed and heated, and the oxide pellets are directly reduced in the upper region of the hydrogen-based vertical shaft furnace. Utilizing the difference in reduction potential between iron oxide and titanium oxide, iron oxide is preferentially reduced to metallic iron, while titanium remains a metallic oxide. An induced magnetic field is applied around the furnace cylinder in the lower part of the hydrogen-based vertical shaft furnace to perform electromagnetic induction heat treatment on the metallized pellets inside the furnace. On the one hand, this heats the reduced pellets, inducing iron grain growth and creating conditions for the subsequent full dissociation of iron and titanium. On the other hand, by increasing the temperature of the metallized pellets, the reducing gas is heated, solving the problem of insufficient heat during hydrogen-based reduction in the furnace.

[0046] S5. The reduced pellets from S4 are crushed, ball-milled, finely ground, and then magnetically separated to obtain reduced iron powder and high-titanium slag.

[0047] In step S5 of this invention, magnetic separation utilizes the difference in magnetism between metallic iron and titanium oxide to separate metallic iron and titanium oxide, ultimately obtaining two products: reduced iron powder and high-titanium slag, thus achieving the separation and recovery of titanium and iron from vanadium extraction slag.

[0048] As an optional implementation, in step S1, the TFe content in the sodium vanadium extraction slag is 48%–62%, the TiO2 content is 5%–15%, the alkali metal content is 1%–3%, and the aluminosilicate content is greater than 7%.

[0049] As an optional implementation, in step S2, the acid used for pickling is composed of sulfuric acid and hydrofluoric acid, the mass ratio of sulfuric acid to hydrofluoric acid is 0 to 2, and the amount of acid used for pickling is 0.1 to 5.0 g / L.

[0050] As an optional implementation, in step S2, the acid leaching temperature is 60-90°C and the time is 30-150 min; the alkali metal content in the acid leaching residue is less than 0.29%, and the aluminosilicate content is less than 3%.

[0051] As an optional implementation, in step S2, the acid leaching residue needs to be precipitated and concentrated in a sedimentation tank before filtration. The concentrated acid leaching residue is then filtered and dewatered by a filter press or a disc vacuum filter. After dewatering, the material is subjected to a high-pressure roller mill.

[0052] As an optional implementation, in step S3, the organic composite adhesive is composed of sodium humate, starch and polyacrylamide; the mass ratio of sodium humate, starch and polyacrylamide is 1-3:3-1:0.05-0.2; and the amount of the organic composite adhesive is 0.1-0.8 wt%.

[0053] In this invention, to avoid introducing new aluminosilicate impurities, the pelletizing binder is an organic composite binder.

[0054] As an optional implementation, step S3 includes three stages of oxidative roasting: a drying stage, a preheating stage, and a roasting stage. The temperature of the drying stage is 180–350°C, and the time is 4–10 min. The temperature of the preheating stage is 800–1100°C, and the time is 10–18 min. The temperature of the roasting stage is 1250–1380°C, and the time is 15–30 min.

[0055] As an optional implementation, in step S3, the compressive strength of the vanadium extraction slag oxide pellets is 2500-3000 N / P.

[0056] As an optional implementation, in step S4, the heating current frequency of the induction furnace is 100-800 Hz, the holding heating temperature is 1000-1200°C, and the holding heating time is 30-120 min.

[0057] As an optional implementation, in step S5, the proportion of particles finely ground to -0.074mm is 35-50%; the magnetic field strength of the magnetic separation is 500Gs-2000Gs.

[0058] The specific implementation methods of this application have been described above. In order to objectively explain the technical effects produced by this application, the following embodiments will be used to describe them.

[0059] Example 1

[0060] A method for hydrogen-based reduction-magnetic separation and recovery of iron and titanium from vanadium extraction slag:

[0061] In this embodiment, vanadium extraction slag from vanadium-titanium magnetite concentrate has the following composition: iron content 48.3%, TiO2 content 14.64%, SiO2 content 6.3%, Al2O3 content 3.2%, and N... a2 The oxygen content is 2.9%, and 45% of the raw ore has a particle size smaller than 0.074 mm. Figure 1 The process shown describes the treatment of vanadium-titanium magnetite concentrate sodium vanadium extraction slag, including the following steps:

[0062] S1. The vanadium-titanium magnetite concentrate sodium-treated vanadium extraction slag is wet-ball-milled to achieve a particle size of -0.074mm (70.5%) and a specific surface area of ​​1008m². 2 / g;

[0063] S2. The finely ground vanadium-extracting slag was subjected to acid leaching to remove impurities. The acid dosage was 0.1 g / L (mass ratio, sulfuric acid: hydrofluoric acid = 0:2), and the leaching was carried out at 60℃ for 150 min. After acid washing, the total amount of vanadium-extracting slag (SiO2+Al2O3) was 2.45%, and the alkali metal content (Na2O+K2O) was 0.28%.

[0064] S3. The acid leaching residue generated in step S2 is concentrated in a sedimentation tank, then filtered through a filter press. After dewatering, the material is subjected to a high-pressure roller mill to achieve a particle size of -0.074mm (80.9%) and a specific surface area of ​​1706 μm. 2 / g; The pelletizing binder is an organic composite binder (sodium humate: starch: PAM = 3:1:0.1), with a dosage of 0.1wt%. The calcination equipment is a chain grate rotary kiln or a belt calciner. The calcination process is as follows: First, drying is carried out at a temperature of 180℃ for 10 minutes with a drying wind speed of 1.2m / s. Second, preheating is carried out at a temperature of 910℃ for 18 minutes. Finally, oxidation calcination is completed at a temperature of 1250℃ for 30 minutes. The wind speed in both the preheating and calcination sections is 2.4m / s. The compressive strength of the oxidized pellets after calcination is 2510N / P.

[0065] S4. The oxidized pellets are reduced in a hydrogen-based vertical shaft furnace using pure hydrogen as the reducing agent. The upper and middle sections are the reduction zone, with a reduction temperature of 800℃ and a reduction time of 90 min. The gas pressure inside the furnace is 0.2 MPa. The lower section of the furnace is the electromagnetic induction heat treatment zone, with an induction furnace heating current frequency of 100 Hz, a holding temperature of 1200℃, and a holding time of 30 min. After reduction, the metallization rate of the reduced pellets is 92.3%.

[0066] S5. The reduced pellets after electromagnetic induction heat treatment are crushed and ball-milled to a fine powder size of -0.074mm (35% of the pellets). A cylindrical weak magnetic separator is used to separate the fine abrasive material at a magnetic field strength of 500 Gs. Two products are obtained: magnetic reduced iron powder and non-magnetic high-titanium slag, achieving efficient separation and recycling of iron and titanium.

[0067] Using the above method, the TiO2 content in the high-titanium slag in the whole process is 70.11%, and the titanium recovery rate is 90.1%; the iron grade in the molten iron product is 90.1%, and the total iron recovery rate is 90.14%.

[0068] Example 2

[0069] A method for hydrogen-based reduction-magnetic separation and recovery of iron and titanium from vanadium extraction slag:

[0070] In this embodiment, a vanadium-titanium magnetite concentrate sodium vanadium extraction slag is used, which has an iron content of 61.86%, a TiO2 content of 5.57%, a SiO2 content of 5.36%, an Al2O3 content of 1.75%, a Na2O content of 1.2%, and a raw ore particle size of less than 0.074 mm accounting for 64.7%. The treatment of the vanadium-titanium magnetite concentrate sodium vanadium extraction slag includes the following steps:

[0071] S1. The vanadium-titanium magnetite concentrate sodium-treated vanadium extraction slag is wet-ball-milled to achieve a particle size of -0.074mm (80.2%) and a specific surface area of ​​1498m². 2 / g;

[0072] S2. The finely ground vanadium extraction slag was subjected to acid leaching to remove impurities. The acid dosage was 5.0 g / L (mass ratio, sulfuric acid: hydrofluoric acid = 2:1), and the leaching was carried out at 90℃ for 30 min. After acid washing, the total amount of vanadium extraction slag (SiO2+Al2O3) was 1.34%, and the alkali metal content (Na2O+K2O) was 0.18%.

[0073] S3. The acid leaching residue generated in step S2 is concentrated in a sedimentation tank, then filtered through a filter press. After dewatering, the material is subjected to a high-pressure roller mill to achieve a particle size of -0.074mm (94.7%) and a specific surface area of ​​2097μm. 2 / g; The pelletizing binder is an organic composite binder (sodium humate: starch: PAM = 1:3:0.2), with a dosage of 0.5wt%. The calcination equipment is a chain grate machine-rotary kiln. The calcination process is as follows: First, drying is carried out at a temperature of 350℃ for 4 minutes with a drying wind speed of 1.2m / s. Second, preheating is carried out at a temperature of 1100℃ for 10 minutes. Finally, calcination is completed at a temperature of 1380℃ for 15 minutes. The wind speed in both the preheating and calcination sections is 2.4m / s. The compressive strength of the oxidized pellets after calcination is 3001N / P.

[0074] S4. The oxidized pellets are reduced in a hydrogen-based vertical shaft furnace. The reducing agent is pure hydrogen. The upper and middle areas are the reduction zones. The reduction temperature is 1000℃, the reduction time is 60 min, and the gas pressure inside the furnace is 0.5 MPa. During electromagnetic induction heat treatment in the lower part of the vertical shaft furnace, the heating current frequency of the induction furnace is 800 Hz, the holding temperature is 1100℃, and the holding time is 90 min. After reduction, the metallization rate of the reduced pellets is 80.7%.

[0075] S5. The reduced pellets after electromagnetic induction heat treatment are crushed and wet-milled to a fine powder size of -0.074mm (49.55%). A cylindrical weak magnetic separator is then used to separate the fine abrasive material at a magnetic field strength of 2000 Gs. Two products are obtained: magnetic reduced iron powder and non-magnetic high-titanium slag, achieving efficient separation and recycling of iron and titanium.

[0076] Using the above methods, the TiO2 content in the high-titanium slag throughout the entire process was 70.51%, and the titanium recovery rate was 90.44%; the iron grade in the reduced iron powder product was 90.63%, and the total iron recovery rate was 91.84%.

[0077] Example 3

[0078] A method for hydrogen-based reduction-magnetic separation and recovery of iron and titanium from vanadium extraction slag:

[0079] In this embodiment, a vanadium-titanium magnetite concentrate sodium vanadium extraction slag is used, which has an iron content of 55.1%, a TiO2 content of 12.34%, a SiO2 content of 7.1%, an Al2O3 content of 3.56%, a Na2O content of 2.5%, and a raw ore particle size of less than 0.074 mm accounting for 63.8%. The treatment of the vanadium-titanium magnetite concentrate sodium vanadium extraction slag includes the following steps:

[0080] S1. The vanadium-titanium magnetite concentrate sodium-treated vanadium extraction slag is wet-milled to achieve a particle size of -0.074mm (75.2%) and a specific surface area of ​​1204m². 2 / g;

[0081] S2. The finely ground vanadium extraction slag was subjected to acid leaching to remove impurities. The acid dosage was 1.5 g / L (mass ratio, sulfuric acid: hydrofluoric acid = 2:1), and the leaching was carried out at 80℃ for 120 min. After acid washing, the total amount of vanadium extraction slag (SiO2+Al2O3) was 2.68%, and the alkali metal content (Na2O+K2O) was 0.21%.

[0082] S3. The acid leaching residue generated in step S2 is concentrated in a sedimentation tank, then filtered through a filter press. After dewatering, the material is subjected to a high-pressure roller mill to achieve a particle size of -0.074mm (89.7%) and a specific surface area of ​​1950 μm. 2 / g; The pelletizing binder is an organic composite binder (sodium humate: starch: PAM = 2:2:0.1), with a dosage of 0.3wt%. The calcination equipment is a belt calciner. The calcination process is as follows: First, drying is carried out at a temperature of 300℃ for 6 minutes with a drying wind speed of 1.2m / s. Second, preheating is carried out at a temperature of 1000℃ for 15 minutes. Finally, calcination is completed at a temperature of 1280℃ for 25 minutes with a wind speed of 2.4m / s in both the preheating and calcination sections. The compressive strength of the oxidized pellets after calcination is 2760N / P.

[0083] S4. The calcined pellets were reduced in a hydrogen-based vertical shaft furnace. The reducing agent was H2:CO = 2.5 (volume percentage). The reduction temperature was 900℃, the reduction time was 90min, and the gas pressure inside the furnace was 0.3MPa. During electromagnetic induction heat treatment in the lower part of the vertical shaft furnace, the heating current frequency of the induction furnace was 200Hz, the holding temperature was 1050℃, and the holding time was 45min. After reduction, the metallization rate of the reduced pellets was 89.2%.

[0084] S5. The reduced pellets after electromagnetic induction heat treatment are crushed and wet-milled to a fineness of -0.074mm with a content of 50%. A cylindrical weak magnetic separator is used to separate the fine abrasive material with a magnetic field strength of 1000Gs. Two products are obtained: magnetic reduced iron powder and non-magnetic high-titanium slag, achieving efficient separation and recycling of iron and titanium.

[0085] Using the above methods, the TiO2 content in the high-titanium slag throughout the entire process was 72.11%, and the titanium recovery rate was 91.4%; the iron grade in the reduced iron powder product was 90.2%, and the total iron recovery rate was 90.23%.

[0086] Example 4

[0087] A method for hydrogen-based reduction-magnetic separation and recovery of iron and titanium from vanadium extraction slag:

[0088] In this embodiment, a vanadium-titanium magnetite concentrate sodium vanadium extraction slag is used, which has an iron content of 58.2%, a TiO2 content of 11.5%, a SiO2 content of 7.0%, an Al2O3 content of 3.9%, a Na2O content of 3.1%, and a raw ore particle size of less than 0.074 mm accounting for 65.3%. The treatment of the vanadium-titanium magnetite concentrate sodium vanadium extraction slag includes the following steps:

[0089] S1. The vanadium-titanium magnetite concentrate sodium-treated vanadium-refining slag is ball-milled to achieve a particle size of -0.074mm (75.9%) and a specific surface area of ​​1050m². 2 / g;

[0090] S2. The finely ground vanadium extraction slag was subjected to acid leaching to remove impurities. The acid dosage was 1.5 g / L (mass ratio, sulfuric acid: hydrofluoric acid = 1:1), and leaching was carried out at 80℃ for 120 min. After acid leaching, the total amount of vanadium extraction slag (SiO2 + Al2O3) was 2.93%, and the alkali metal content (Na2O + K2O) was 0.20%.

[0091] S3. The acid leaching residue generated in step S2 is concentrated in a sedimentation tank, then filtered through a filter press. After dewatering, the material is subjected to a high-pressure roller mill to achieve a particle size of -0.074mm (88.97%) and a specific surface area of ​​1990 μm. 2 / g; The pelletizing binder is an organic composite binder (sodium humate: starch: PAM = 2:2:0.1), with a dosage of 0.5wt%. The calcination equipment is a belt calciner. The calcination process is as follows: First, drying is carried out at a temperature of 300℃ for 6 minutes with a drying wind speed of 1.2m / s. Second, preheating is carried out at a temperature of 1000℃ for 15 minutes. Finally, calcination is completed at a temperature of 1350℃ for 20 minutes. The wind speed in both the preheating and calcination sections is 2.4m / s. The compressive strength of the oxidized pellets after calcination is 2891N / P.

[0092] S4. The calcined pellets were reduced in a hydrogen-based vertical shaft furnace. The reducing agent was H2:CO = 6.0 (volume percentage). The reduction temperature was 1000℃, the reduction time was 90 min, and the gas pressure inside the furnace was 0.35 MPa. During electromagnetic induction heat treatment in the lower part of the vertical shaft furnace, the heating current frequency of the induction furnace was 100 Hz, the holding temperature was 1050℃, and the holding time was 45 min. After reduction, the metallization rate of the reduced pellets was 92.3%.

[0093] S5. The reduced pellets after electromagnetic induction heat treatment are crushed and wet-milled to a fineness of -0.074mm with a content of 50%. A cylindrical weak magnetic separator is used to separate the fine abrasive material with a magnetic field strength of 1000Gs. Two products are obtained: magnetic reduced iron powder and non-magnetic high-titanium slag, achieving efficient separation and recycling of iron and titanium.

[0094] Using the above methods, the TiO2 content in the high-titanium slag throughout the entire process was 71.85%, and the titanium recovery rate was 90.4%; the iron grade in the reduced iron powder was 90.5%, and the total iron recovery rate was 91.00%.

[0095] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation, characterized in that, Includes the following steps: S1. Vanadium-titanium magnetite concentrate is subjected to sodium vanadium extraction to obtain sodium vanadium extraction slag; the sodium vanadium extraction slag is finely ground to make its particle size of -0.074mm account for 70~80%, and its specific surface area is 1100~1500m². 2 / g; wherein, the TFe content in the sodium vanadium extraction slag is 48%~62%, the TiO2 content in the sodium vanadium extraction slag is 5%~15%, the alkali metal content in the sodium vanadium extraction slag is 1%~3%, and the aluminosilicate content is greater than 7%; S2. The finely ground vanadium-containing sodium leaching slag from S1 is subjected to acid leaching to obtain acid-leached slag. The acid-leached slag is then filtered, dewatered, and then subjected to high-pressure roller milling to achieve a particle size of -0.074mm (80-95%) and a specific surface area of ​​1700-2100 m². 2 / g; S3. The material after high-pressure roller milling in S2 is mixed with an organic composite binder and then pelletized to obtain green pellets with a particle size of 10-16 mm. The green pellets are then oxidized and calcined to obtain vanadium extraction slag oxidized pellets with a compressive strength of 2500-3000 N / P. The organic composite binder is composed of sodium humate, starch, and polyacrylamide; the mass ratio of sodium humate, starch, and polyacrylamide is 1-3:3-1:0.05-0.2; and the amount of organic composite binder is 0.1-0.8 wt%. S4. The hot vanadium-extraction slag oxide pellets after S3 oxidation roasting are directly reduced in a hydrogen-based vertical shaft furnace to obtain reduced pellets containing strongly magnetic elemental iron and non-magnetic titanium oxides. The hot vanadium-extraction slag oxide pellets are added from the top of the hydrogen-based vertical shaft furnace. The hydrogen-based gas in the furnace is first heated through external heat exchange tubes, then introduced through a gas supply pipe surrounding the furnace cylinder at the bottom; and then through a gas supply pipe installed on the lower side wall of the furnace cylinder. Some electromagnetic induction heat treatment devices complete secondary heating and reforming; the hydrogen-based gas in the hydrogen-based vertical furnace is H2 or a mixture of H2 and CO; the temperature of the reduction zone in the upper part of the hydrogen-based vertical furnace is 800~1000℃, the gas pressure is 0.2~0.5MPa, and the reduction time is 60~150min; the heating current frequency of the induction furnace is 100~800HZ, the holding heating temperature is 1000~1200℃, and the holding heating time is 30~120min; S5. The reduced pellets from S4 are crushed, ball-milled, and finely ground until the -0.074mm content is 35~50%, and then subjected to magnetic separation to obtain reduced iron powder and high titanium slag; wherein the magnetic field strength of the magnetic separation is 500Gs~2000Gs.

2. The method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation according to claim 1, characterized in that, In step S2, the acid used for acid leaching is composed of sulfuric acid and hydrofluoric acid, the mass ratio of sulfuric acid to hydrofluoric acid is 1~2, and the amount of acid used for acid leaching is 0.1~5.0 g / L.

3. The method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation according to claim 1, characterized in that, In step S2, the acid leaching temperature is 60~90℃ and the time is 30~150min; the alkali metal content in the acid leaching residue is less than 0.29% and the aluminosilicate content is less than 3%.

4. The method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation according to claim 1, characterized in that, In step S2, the acid leaching residue needs to be precipitated and concentrated in a sedimentation tank before filtration. The concentrated acid leaching residue is then filtered and dewatered by a filter press or a disc vacuum filter. After dewatering, the material is subjected to a high-pressure roller mill.

5. The method for separating and recovering iron and titanium from vanadium extraction slag using hydrogen-based reduction-magnetic separation according to claim 1, characterized in that, In step S3, the oxidative calcination includes three stages: a drying stage, a preheating stage, and a calcination stage. The temperature of the drying stage is 180~350℃, and the time is 4~10 min. The temperature of the preheating stage is 800~1100℃, and the time is 10~18 min. The temperature of the calcination stage is 1250~1380℃, and the time is 15~30 min.

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