Method for clean extraction and utilization of valuable elements in perovskite

Abstract

The application discloses a method for cleaning extraction and utilization of valuable elements in a perovskite, and comprises the following steps: S1. oxidizing roasting: directly performing oxidizing roasting on the perovskite powder at 800-1080 DEG C; S2. vanadium extraction by leaching: extracting vanadium from the perovskite in an acid solution to obtain a vanadium precipitation liquid and a leached residue; S3. primary impurity removal: removing impurities in the leached residue by acidolysis in concentrated sulfuric acid to obtain a primary titanium-containing mother liquor and a primary tailing; S4. secondary impurity removal: removing impurities in the primary tailing by acidolysis in concentrated sulfuric acid to obtain a secondary titanium-containing mother liquor and a secondary tailing; and S5. adding a certain amount of water to the primary titanium-containing mother liquor and the secondary titanium-containing mother liquor as a leaching liquid for normal titanium concentrate acidolysis solid phase. The method can effectively separate and extract valuable elements vanadium, titanium and calcium in the perovskite, and the utilization rate of waste liquid and waste solid in the process is relatively high and close to 99%.

Description

Technical Field

[0001] This invention belongs to the field of mineral element recycling technology, specifically relating to a method for the clean extraction and utilization of valuable elements in perovskite. Background Technology

[0002] The Panxi region of Sichuan Province in my country possesses abundant titanium ore resources, accounting for over 90% of the national total. Several large mining areas exist in the region, such as the Panzhihua, Hongge, Taihe, and Baima mining areas. The titanium ore in this region is rich in vanadium, hence the name vanadium-titanium magnetite. Vanadium-titanium magnetite in the Panxi region often occurs with impurities such as calcium and magnesium, making its beneficiation process complex, resulting in poor beneficiation and low-grade titanium concentrate. Vanadium-titanium magnetite is beneficiated through gravity separation, magnetic separation, and flotation to obtain iron and titanium concentrates. After beneficiation, nearly 50% TiO2 enters the iron concentrate, which still contains approximately 10% TiO2. The iron concentrate is then smelted in a blast furnace to obtain molten iron and blast furnace slag, which still contains over 20% TiO2. The utilization of titanium in blast furnace slag has always been a key focus both domestically and internationally. However, due to the elemental composition of blast furnace slag, it is primarily used as a building material, resulting in a significant waste of titanium resources. Furthermore, the technology for extracting titanium is not yet industrially scalable. Hundreds of millions of tons of blast furnace slag remain in slag dumps, thus necessitating the discovery of suitable processes for its comprehensive utilization.

[0003] Currently, the most researched extraction process for titanium from blast furnace slag focuses on the selective precipitation and separation of perovskite from blast furnace slag. This process involves further high-temperature treatment of titanium-containing slags such as blast furnace slag, causing the precipitation and growth of titanium-containing mineral phases. These phases are then separated and enriched through beneficiation processes such as magnetic separation, gravity separation, and flotation to obtain perovskite. This perovskite contains only about 40% TiO2, but high levels of elements such as vanadium, calcium, magnesium, and aluminum, especially calcium (around 30%) and vanadium (around 5%). It also exhibits poor acid solubility, making titanium utilization a challenge. However, its low iron content (<0.5%) eliminates the need for subsequent iron removal through crystallization.

[0004] This invention focuses on the extraction of elements such as titanium, vanadium, and calcium from perovskite obtained by blast furnace slag sorting, aiming to provide a reference for the utilization of valuable elements in blast furnace slag and further improve the utilization rate of elements in vanadium-titanium magnetite. Summary of the Invention

[0005] The purpose of this invention is to provide a method for the clean extraction and utilization of valuable elements in perovskite in order to overcome the shortcomings of the prior art.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A method for the clean extraction and utilization of valuable elements in perovskite includes the following steps:

[0008] S1. Oxidative roasting: The ground and sieved perovskite powder is directly oxidized and roasted at 800-1080℃, with oxygen introduced during the roasting process;

[0009] S2. Vanadium extraction by leaching: The roasted perovskite is leached in an acid solution of 0.4 to 1 mol / L at a leaching temperature of 60 to 80°C. After leaching, solid-liquid separation is performed to obtain vanadium-precipitated liquid and leaching residue.

[0010] S3. Primary impurity removal: The leaching residue is mixed evenly with concentrated sulfuric acid of 93-98% by mass, and then dilute sulfuric acid or water is added to initiate the reaction. Ensure that the total sulfuric acid mass fraction in the reaction liquid is above 85% and the liquid-to-solid mass ratio is ≥1.8:1. A certain heat source is provided at the beginning of the reaction until the system reaction temperature reaches 140-160℃ and then it is stopped. If the material solidifies, it is then aged at 170-190℃ for 1.5-2.5 hours after solidification. If the material does not solidify, the total reaction time is controlled to be 20-40 minutes.

[0011] After the reaction, water was added for leaching, followed by sedimentation, to obtain a titanium-containing mother liquor and a tailings.

[0012] S4. Secondary impurity removal: The primary tailings are mixed evenly with concentrated sulfuric acid of 93-98% by mass, and then dilute sulfuric acid or water is added to initiate the reaction. The total sulfuric acid mass fraction in the reaction liquid is ensured to be above 90%, and the liquid-solid mass ratio is (1.0-1.5):1. A certain heat source is provided at the beginning of the reaction until the system reaction temperature reaches 140-160℃ and then it is stopped. After the material solidifies, it is further matured at 170-190℃ for 1-2 hours.

[0013] After the reaction, water was added for leaching, followed by sedimentation, to obtain a secondary titanium-containing mother liquor and a secondary tailings.

[0014] S5. Add a certain amount of primary water to the primary titanium-containing mother liquor obtained in step S3 and the secondary titanium-containing mother liquor obtained in step S4 to make a leaching solution for the normal titanium concentrate acid hydrolysis solid phase. The amount of primary titanium-containing mother liquor and secondary titanium-containing mother liquor added during leaching is 5 to 20% of the total mass of the leaching solution.

[0015] Preferably, the elemental content in the perovskite, by mass fraction, is: TiO2 35-45%, CaO 25-35%, Fe2O3 <0.5%, and V2O5 3-5%.

[0016] Preferably, the perovskite powder in step S1 contains ≥90% -325 mesh particles by mass.

[0017] Preferably, the oxidative calcination time in step S1 is 0.5 to 2 hours.

[0018] Preferably, the liquid-to-solid ratio in step S2 is (4-10):1mL / g, and the leaching time is 6-12h.

[0019] Preferably, the vanadium precipitate liquid obtained in step S2 is used to produce vanadium pentoxide products.

[0020] Preferably, the secondary tailings obtained in step S4 are washed with water until neutral to obtain calcium sulfate product.

[0021] Preferably, flocculants are added during sedimentation in steps S3 and S4.

[0022] Preferably, in step S3, the liquid-to-ore mass ratio for water leaching is 2-2.3:1, all leaching solutions are made from primary water, the leaching temperature is 60-65℃, and the leaching time is 3-5 hours.

[0023] In step S4, the liquid-to-ore mass ratio for water leaching is 1.5–2.1:1, all leaching solutions are made from primary water, the leaching temperature is 60–65°C, and the leaching time is 3–5 hours.

[0024] Preferably, the leaching liquid-to-ore mass ratio in step S5 is 2.4–2.5:1, the leaching temperature is 64–66°C, and the leaching time is 4–4.5 h.

[0025] Compared with the prior art, this application has the following beneficial effects:

[0026] (1) The method of the present invention can effectively separate and extract valuable elements vanadium, titanium, and calcium from perovskite, wherein the extraction rate of vanadium is ≥89%, the extraction rate of titanium is ≥85%, and the extraction rate of calcium is ≥92%. This process is a clean processing process for perovskite, and the utilization rate of waste liquid and solid waste in the process is high, close to 99%.

[0027] (2) Due to the high content of impurities such as magnesium and aluminum in perovskite, titanium extraction is difficult. This application adopts a two-stage impurity removal process involving reaction with sulfuric acid, resulting in lower process costs. Due to the high calcium content, calcium sulfate will be generated during acid hydrolysis, which will coat the mineral particles and hinder the reaction. The second acid hydrolysis will further increase the reaction rate between the elements and sulfuric acid, thereby increasing the titanium leaching rate. This process uses a high acid-to-mineral ratio and a high acid concentration for experiments. The high acid-to-mineral ratio helps to extend the reaction time and make the reaction more complete, while the high acid concentration helps to increase the energy of the system, which helps the elements in the perovskite to react fully with sulfuric acid and reduces the adverse effects of calcium sulfate coating the mineral particles on the reaction.

[0028] (3) The perovskite has a low iron content, so no crystallization process is required in the later stage, and no ferrous sulfate waste is generated. The perovskite structure contains stable magnesium aluminum spinel. During acid leaching, magnesium aluminum spinel does not easily react with concentrated sulfuric acid, and the proportion of impurities entering the liquid is small, resulting in a relatively pure titanium solution. Attached Figure Description

[0029] Figure 1 This is an electron microscope image of the tailings obtained in Example 1 of this application (the circled area represents magnesium aluminum spinel). Detailed Implementation

[0030] The perovskite processed in this application is generally a product separated from blast furnace slag, with a calcium content as high as about 30% and a titanium grade of about 40%, which is lower than that of domestic titanium concentrate. This perovskite has high levels of impurities such as calcium, magnesium, and aluminum, poor acid solubility, and difficulty in titanium extraction. However, its iron content is low (<0.5%), eliminating the need for subsequent crystallization and iron removal processes. Furthermore, electron microscopy analysis shows that the perovskite structure contains stable magnesium aluminum spinel, making it resistant to reaction with concentrated sulfuric acid.

[0031] The elemental composition of a typical perovskite used in this application is shown in Table 1. The last row of Table 1 shows the elemental composition of a typical titanium concentrate. As can be seen from the table, compared with conventional titanium concentrate, perovskite has higher calcium, magnesium, and aluminum content, and lower titanium and iron content. The last column shows the liquid-solid ratio during acid leaching. In this application, acid leaching refers to the primary impurity removal step.

[0032] Table 1

[0033]

[0034] Based on the above, this invention provides a method for the clean extraction and utilization of valuable elements in perovskite, specifically including the following steps:

[0035] S1. Oxidative roasting: The ground and sieved perovskite powder is directly oxidized and roasted at 800-1080℃. Oxygen is introduced during the roasting process to accelerate the oxidation of vanadium. The preferred oxidative roasting time is 0.5-2 hours.

[0036] S2. Vanadium extraction by leaching: The roasted perovskite is leached in an acid solution of 0.4 to 1 mol / L at a leaching temperature of 60 to 80°C. After leaching, solid-liquid separation is performed to obtain vanadium-precipitated liquid and leaching residue.

[0037] In conventional vanadium extraction processes, titanium slag ore requires the addition of a calcining agent to form agglomerates before calcination. However, the perovskite in this application has a high calcium content, which can serve as a calcining agent, eliminating the need for additional addition. Furthermore, it possesses a stable magnesium-aluminum spinel structure, capable of withstanding high-temperature and high-pressure roasting, thus eliminating the need for agglomeration. Moreover, due to the poor acid solubility of perovskite, it is preferable to grind and sieve the perovskite before oxidative roasting, preferably grinding it until the mass percentage of -325 mesh particles in the perovskite powder is ≥90%.

[0038] Since the perovskite in this application is not agglomerated, a relatively low roasting temperature (conventional oxidative roasting is above 1100℃) is sufficient to achieve good roasting results. The roasting process can be divided into three stages: first, the structure of the vanadium mineral is destroyed; second, low-valence vanadium oxides are oxidized to form V₂O₅; and third, V₂O₅ combines with CaO, and vanadium reacts with some calcium oxide to form calcium vanadate xCaO·V₂O₅ (x=1, 2, 3). All three types of calcium vanadate are acid-soluble substances and dissolve well in low-concentration acidic solutions. Under low-concentration acid conditions, the leaching rate of other impurity elements is low, and no other impurities are introduced into the vanadium leaching solution. Because the concentration of the leaching acid solution is lower than that of conventional leaching, this application requires a higher leaching temperature (conventional leaching temperatures are generally <50℃). At higher leaching temperatures, the leaching time can be significantly shortened. The preferred leaching time is 6–12 h, and the liquid-to-solid ratio is (4–10):1 mL / g.

[0039] The reactions involved in the vanadium extraction process are as follows:

[0040] V2O5+xCaO=xCaO·V2O5(x=1,2,3).

[0041] Since no additional calcining agent is added in the vanadium extraction roasting process of this application, and the leaching rate of impurities is also low under low acid concentration during acid leaching, the impurity content in the obtained vanadium precipitation liquid is low. The concentration of V in the vanadium precipitation liquid is ≥2.3g / L, and the vanadium leaching rate is ≥89%, which can be used to produce vanadium pentoxide products.

[0042] S3. Primary impurity removal: The leaching residue is mixed evenly with concentrated sulfuric acid (93-98% by mass). To ensure thorough mixing, a mixing time of 20 minutes is preferred. Then, dilute sulfuric acid or water is added to initiate the reaction, ensuring that the total sulfuric acid mass fraction in the reaction liquid is above 85% and the liquid-to-solid mass ratio is ≥1.8:1. A certain heat source is provided at the beginning of the reaction until the system reaction temperature reaches 140-160℃. If the material solidifies, it is allowed to mature for another 1.5-2.5 hours. If the material does not solidify, the total reaction time is controlled to be 20-40 minutes. The total reaction time is calculated from the start of the reaction initiated by adding dilute hydrochloric acid or water.

[0043] After the reaction, water was added for leaching, followed by sedimentation, to obtain a titanium-containing mother liquor and a tailings.

[0044] Based on the elemental composition of perovskite in Table 1, the exothermic reaction of perovskite acid leaching is calculated to be approximately 189.04 kJ / 100g, while the exothermic reaction of conventional titanium concentrate acid leaching is approximately 108.34 kJ / 100g. Due to its high calcium content, this titanium ore releases a significant amount of heat during acid leaching. However, the calcium sulfate produced by the reaction of calcium with sulfuric acid adheres to the surface of the ore particles, encapsulating them and hindering the spontaneous acid leaching reaction. Therefore, a larger amount of sulfuric acid is required to prolong the reaction time, and a higher concentration of sulfuric acid is necessary to ensure sufficient reaction between the elements and the sulfuric acid. Thus, this application employs a higher liquid-to-solid ratio (≥1.8:1) and a higher acid concentration (≥85%) for perovskite acid leaching. A certain heat source is provided at the beginning of the reaction until the system reaction temperature reaches 140–160°C, after which the reaction is stopped. Subsequent spontaneous reactions are exothermic, with the system temperature potentially exceeding 200°C. After the heat source is stopped, the material solidifies after 5–8 minutes of high-temperature reaction, becoming a steel-gray solid phase. The solid material is further aged at 170–190℃ for 1.5–2.5 hours to ensure complete reaction with sulfuric acid. When the acid concentration is low, the water content in the reaction system is high. After several tens of minutes of high-temperature reaction, the material remains in a viscous slurry and cannot solidify. In this case, aging is not necessary, and acid hydrolysis is maintained in the liquid phase. Compared to the solidification reaction system, the acid hydrolysis time is shorter, and the material is more uniformly extracted. However, the overall acid hydrolysis rate is lower than that of the solidification reaction.

[0045] The preferred reaction acid concentration is ≥90%, as a higher concentration can improve the titanium extraction rate. This process converts titanium in perovskite into titanium oxysulfate, while impurities such as iron, calcium, magnesium, and aluminum are converted into sulfates. After water leaching, solid titanium oxysulfate is converted into liquid titanium oxysulfate. The main chemical reactions involved in this step are as follows:

[0046] TiO2 + H2SO4 = TiOSO4 + H2O;

[0047] Fe2O3+H2SO4=Fe2(SO4)3↓+H2O;

[0048] FeO + H₂SO₄ = FeSO₄ + H₂O;

[0049] CaO + H₂SO₄ = CaSO₄↓ + H₂O;

[0050] Al2O3+3H2SO4=Al2(SO4)3+3H2O;

[0051] MgO + H₂SO₄ = MgSO₄ + H₂O;

[0052] Because the perovskite in this application has a low iron content, a subsequent crystallization and iron removal process is not required. Furthermore, its structure contains stable magnesium aluminum spinel, which does not readily react with concentrated sulfuric acid. Therefore, the resulting titanium solution has a low impurity content. Figure 1As shown, electron microscopy analysis revealed that the primary tailings contained regularly shaped magnesium aluminum spinel with a smooth surface that was not corroded by sulfuric acid.

[0053] Because of the high calcium content in perovskite, the calcium sulfate encapsulates the mineral particles significantly during acid leaching, resulting in incomplete reaction of elements such as titanium. Therefore, a second acid leaching process is required on the tailings, as described in step S3. This process further converts titanium in the tailings into titanium oxysulfate, while impurities such as calcium, magnesium, and aluminum are converted into sulfates.

[0054] S4. Secondary Purification: The primary tailings are mixed evenly with concentrated sulfuric acid (93-98% by mass). For thorough mixing, a mixing time of 20 minutes is preferred. Then, dilute sulfuric acid or water is added to initiate the reaction, ensuring the total sulfuric acid mass fraction in the reaction liquid is above 90%, with a liquid-to-solid mass ratio of (1.0-1.5):1. During the secondary purification reaction, the titanium content in the raw materials is low, and the titanium is tightly bound to impurities. A high-acid-concentration reaction system is required. Adding dilute acid or water releases more heat, disrupting the tightly bound structure of titanium and impurities. The liquid-to-solid ratio is determined by the slag composition. Due to the reduced content of elements such as titanium, magnesium, and iron in the secondary reaction raw materials, a higher acid concentration and a lower liquid-to-solid ratio are needed for the secondary purification. A heat source is provided at the beginning of the reaction until the system temperature reaches 140-160℃, after which the reaction is stopped. After stopping the heat source, the material solidifies after several minutes of high-temperature reaction, becoming a steel-gray solid phase. The solid phase is then further aged at 170-190℃ for 1-2 hours.

[0055] After the reaction, water was added for leaching, followed by sedimentation, to obtain a secondary titanium-containing mother liquor and a secondary tailings.

[0056] Flocculants are added during the primary and secondary impurity removal and sedimentation processes to promote impurity sedimentation.

[0057] The resulting secondary titanium-containing mother liquor has a low iron content, eliminating the need for iron removal through crystallization. This process generates no waste solids such as ferrous sulfate.

[0058] The secondary tailings are washed with water until neutral, allowing soluble sulfates to be further washed away, while calcium sulfate accumulates in the slag. Electron microscopy analysis reveals that the secondary slag also contains regularly shaped magnesium aluminum spinel with smooth surfaces, uncorroded by sulfuric acid. The main component of the secondary slag is calcium sulfate, with a calcium recovery rate of ≥90% in this process. The CaSO4·H2O content is ≥85%, SO3 ≥47%, and the pH value is ≥6.5. It can be used to produce building materials, such as cement retarders. The secondary slag from this process has high utilization value, therefore no waste is discharged.

[0059] S5. The primary titanium-containing mother liquor obtained in step S3 and the secondary titanium-containing mother liquor obtained in step S4 are supplemented with a certain amount of primary water as the leaching solution for the normal titanium concentrate acid hydrolysis solid phase. The amount of primary and secondary titanium-containing mother liquor added during leaching is 5-20% of the total mass of the leaching solution.

[0060] The conventional sulfuric acid process for titanium dioxide production mainly includes acid hydrolysis, hydrolysis, primary washing, bleaching, secondary washing, salt treatment, calcination, and post-treatment. Acid hydrolysis uses concentrated sulfuric acid to convert titanium in the titanium concentrate into soluble titanium oxysulfate. After hydrolysis, water is added to leach the soluble titanium oxysulfate from the acid-hydrolyzed solids, yielding a titanium oxysulfate solution. This solution is then purified through sedimentation and crystallization (primarily removing impurities such as ferrous sulfate) to obtain a purified titanium solution. Hydrolysis converts the titanium solution into a water-insoluble hydrated titanium dioxide precipitate, namely metatitanic acid. The hydrolysis process requires very strict control of the titanium oxysulfate solution's hydrolysis conditions. It not only needs to be carried out at suitable pH levels but also depends on appropriate temperature, concentration, and the availability of an effective acid (the sum of sulfuric acid bound to titanium and its free sulfuric acid) to occur and generate metatitanic acid.

[0061] During the leaching of normal titanium concentrate, the acid-hydrolyzed solids require the addition of water, waste acid, and low-acidity water (generally referring to the titanium dioxide-containing filtrate produced during washing processes such as filtration and filter press) to provide a certain amount of acidity to the leaching system, preventing hydrolysis of the titanium solution and stabilizing its F-value. However, the secondary titanium-containing mother liquor obtained after the second acid hydrolysis of perovskite in this application has a high acidity and is not suitable for direct concentration and hydrolysis.

[0062] This application, through research, discovered that mixing it with a certain amount of primary water and using it as the leaching solution for the acid hydrolysis solids in conventional sulfuric acid process titanium dioxide production yields a titanium solution that meets production requirements. This allows for the effective utilization of titanium in perovskite, with a titanium recovery rate exceeding 85%. Simultaneously, it effectively utilizes the acid in the secondary titanium-containing mother liquor. This process generates no waste liquid or solid waste, constituting a clean perovskite processing technology.

[0063] Preferably, in step S3, the liquid-to-ore mass ratio for water leaching is 2-2.3:1, all leaching solutions are made from primary water, the leaching temperature is 60-65℃, and the leaching time is 3-5 hours.

[0064] In step S4, the liquid-to-ore mass ratio for water leaching is 1.5–2.1:1, all leaching solutions are made from primary water, the leaching temperature is 60–65℃, and the leaching time is 3–5 hours.

[0065] In step S5, the liquid-to-ore mass ratio is 2.4–2.5:1, the leaching temperature is 64–66℃, and the leaching time is 4–4.5 h.

[0066] Because the titanium content in ore obtained through primary impurity removal is higher than that obtained through secondary impurity removal, a relatively larger amount of leaching solution is required for leaching. Titanium concentrate, with its even higher titanium content, requires even more leaching solution. It should be particularly noted that the method provided in this application is also suitable for perovskite with similar compositions, and not just for perovskite separated from blast furnace slag.

[0067] Example 1

[0068] 1. Grinding: The perovskite used in the experiment was a product obtained from blast furnace slag using a special sorting method. Its titanium content was relatively low (TiO2: 38.04%). The perovskite was ground to a -325 mesh ratio of 93%.

[0069] 2. Oxidation roasting: The perovskite contains 4.50% vanadium. The perovskite is oxidized and roasted at 1000℃ for 1.5 hours. Oxygen is introduced during the roasting process to accelerate the oxidation of vanadium.

[0070] 3. Vanadium extraction by leaching: The roasted perovskite is leached in dilute sulfuric acid (c(H) + Vanadium was extracted by leaching with a solution of 1 mol / L (liquid:solid) at a liquid-to-solid ratio of 5:1 (mL / g), a leaching temperature of 60℃, and a leaching time of 7 hours. After leaching, the mother liquor, containing approximately 4.5 g / L of vanadium, was used as the vanadium precipitate and was used to produce vanadium pentoxide. The leaching residue was washed and dried. The vanadium leaching rate was approximately 89.5%.

[0071] 4. Primary impurity removal:

[0072] A. Mix the vanadium-extracted perovskite leaching residue with 98% concentrated sulfuric acid for 15 minutes.

[0073] B. Subsequently, 20% waste sulfuric acid was added to initiate the reaction. The reaction acid concentration in the system was 93%, and the mass ratio of sulfuric acid to perovskite was 1.9:1. A heat source was initially provided until the system temperature reached 150°C, at which point the reaction was stopped. During spontaneous reaction, the temperature rose to 210°C. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was then further cured in a 180°C oven for 2 hours to ensure complete reaction with the sulfuric acid.

[0074] C. After aging, cool to below 60℃, add 2.1 times the mass of water to the solid and leach for 4 hours at 63℃. Solid titanium oxysulfate is converted into liquid titanium oxysulfate. After leaching, add flocculant and let settle for 1 hour. Separate the supernatant from the precipitate to obtain primary titanium-containing mother liquor and primary tailings. The primary tailings are washed with water until neutral.

[0075] 5. Secondary impurity removal:

[0076] A. Mix the dried primary tailings with 98% concentrated sulfuric acid evenly for 20 minutes.

[0077] B. Subsequently, 20% waste sulfuric acid was added to initiate the reaction, resulting in a system reaction acid concentration of 90% and a sulfuric acid to slag mass ratio of 1.2:1. The reaction initially provided a heat source until the system temperature reached 150°C, after which it was stopped. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was further aged at 180°C for 1.5 hours. The titanium in the slag further transformed into titanium oxysulfate.

[0078] C. After maturation, cool to below 60℃, add twice the mass of primary water for leaching for 4 hours at 63℃, add flocculant and settle for 1 hour. Separate the supernatant from the lower precipitate to obtain secondary titanium-containing mother liquor and secondary tailings. The obtained secondary titanium-containing mother liquor has a low iron content and does not require iron removal through crystallization. This process does not generate waste solids such as ferrous sulfate.

[0079] 6. Utilization of titanium-containing leaching solutions:

[0080] The titanium-containing liquid extracted from the two impurity removal processes was used as the leaching solution for the normal acid hydrolysis solid phase of titanium concentrate. During leaching, the amount of titanium-containing mother liquor added (the mass ratio of the primary and secondary titanium-containing mother liquors was 1:1) was 5% of the total leaching solution, with the remainder being primary water. The leaching temperature was 65℃, the leaching time was 4 hours, and the leaching solution-to-solid ratio was 2.4:1 (mass ratio). After leaching, a titanium solution meeting production requirements was obtained, thus effectively utilizing titanium in the perovskite, with a titanium recovery rate of approximately 91%.

[0081] 7. Utilization of secondary slag: The secondary slag is washed with water until neutral. The main component of the secondary slag is calcium sulfate, with a calcium recovery rate of 90.5%. The content of CaSO4·H2O is 89.23%, SO3 is 47.55%, and the pH value is 6.7. It is a high-quality raw material for the production of cement retarder.

[0082] Table 2. Elemental content (ppm) of vanadium leaching mother liquor in Example 1

[0083] Fe V Ca Cr Mg Mn Al Ti 252 4520 1002 1.58 997 89.2 978 680

[0084] Table 3. TiO2 content of primary and secondary titanium-containing mother liquors in Example 1.

[0085] sample <![CDATA[TiO2(g / L)]]> <![CDATA[H2SO4(g / L)]]> One-time titanium-containing mother liquor 75.78 330 Secondary titanium-containing mother liquor 49.94 205 Step 6: Immersion of titanium liquid 131 268

[0086] Table 4. Elemental analysis of primary and secondary slag in Example 1 (%)

[0087]

[0088] Example 2

[0089] 1. Grinding: The perovskite used in the experiment was a product obtained from blast furnace slag using a special sorting method. Its titanium grade was low (TiO2: 38.04%), and the proportion of -325 mesh was 90%.

[0090] 2. Oxidation roasting: The perovskite contains 4.45% vanadium. The perovskite is oxidized and roasted at 950℃ for 2 hours. Oxygen is introduced during the roasting process to accelerate the oxidation of vanadium.

[0091] 3. Vanadium extraction by leaching: The roasted perovskite is leached in dilute sulfuric acid (c(H) + Vanadium was extracted by leaching in a solution of 0.8 mol / L (liquid:solid ratio 8:1, mL / g), at a leaching temperature of 65℃ for 10 hours. After leaching, the mother liquor, containing approximately 2.8 g / L of vanadium, was used as the vanadium precipitate and was used to produce vanadium pentoxide. The leaching residue was washed and dried. The vanadium leaching rate was approximately 90.5%.

[0092] 4. First-stage impurity removal:

[0093] A. Mix the vanadium-extracted perovskite with 93% concentrated sulfuric acid evenly for 20 minutes.

[0094] B. Subsequently, 20% waste sulfuric acid was added to initiate the reaction. The concentration of the reacting acid in the system was 85%, and the mass ratio of sulfuric acid to perovskite was 1.8:1. A heat source was initially provided until the system temperature reached 150°C, after which the reaction was stopped. During spontaneous reaction, the temperature rose to 208°C. After 30 minutes of high-temperature reaction, the material was a thick slurry and had not solidified.

[0095] C. Cool the material to below 60°C, add 2 times the mass of water to the thick slurry material and leach for 4 hours at a leaching temperature of 60°C. After leaching, add flocculant and let it settle for 1 hour. Separate the upper clear liquid from the lower sediment to obtain primary titanium-containing mother liquor and primary tailings. Wash the primary tailings with water until neutral.

[0096] 5. Secondary impurity removal:

[0097] A. Mix the dried primary tailings with 98% concentrated sulfuric acid evenly for 20 minutes.

[0098] B. Subsequently, a certain amount of water was added to initiate the reaction. The concentration of the reacting acid in the system was 90%, and the mass ratio of sulfuric acid to slag was 1.25:1. A heat source was provided at the beginning of the reaction until the system temperature reached 150°C, after which the reaction was stopped. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was further aged at 180°C for 2 hours. The titanium in the slag was further converted into titanium oxysulfate.

[0099] C. After maturation, cool to below 60℃, add 1.8 times its mass of primary water for 4 hours at 60℃, add flocculant and let settle for 1 hour. Separate the supernatant from the precipitate to obtain secondary titanium-containing mother liquor and secondary tailings. The obtained secondary titanium-containing mother liquor has a low iron content and does not require iron removal through crystallization. This process does not generate waste solids such as ferrous sulfate.

[0100] 6. Utilization of titanium-containing leaching solutions:

[0101] The titanium-containing liquid extracted from the two impurity removal processes was used as the leaching solution for the normal acid hydrolysis solid phase of titanium concentrate. During leaching, the titanium-containing liquid (the mass ratio of the primary titanium-containing mother liquor to the secondary titanium-containing mother liquor was 1:1) accounted for 20% of the total leaching solution, with the remainder being primary water. The leaching temperature was 65℃, the leaching time was 4.5 h, and the liquid-to-solid ratio was 2.5:1 (mass ratio). After leaching, a titanium solution meeting production requirements was obtained, thus effectively utilizing the titanium in the perovskite, with a titanium recovery rate of approximately 86%.

[0102] 7. Utilization of secondary slag: The secondary slag is washed with water until neutral. The main component of the secondary slag is sulfate, with a calcium recovery rate of 92%. The content of CaSO4·H2O is 87.86%, SO3 is 48.59%, and the pH value is 6.5. It is a high-quality raw material for the production of cement retarder.

[0103] Table 5. Elemental content (ppm) of vanadium leaching mother liquor in Example 2

[0104] Fe V Ca Cr Mg Mn Al Ti 190 2810 850 1.08 680 73.2 580 607

[0105] Table 6. TiO2 content of primary and secondary titanium-containing mother liquors in Example 2.

[0106] sample <![CDATA[TiO2(g / L)]]> <![CDATA[H2SO4(g / L)]]> One-time titanium-containing mother liquor 59.86 335 Secondary titanium-containing mother liquor 45.29 198 Step 6: Immersion of titanium liquid 129 258

[0107] Table 7 Elemental analysis of primary and secondary tailings in Example 2 (%)

[0108]

[0109] Example 3

[0110] 1. Grinding: The perovskite used in the experiment was a product obtained from blast furnace slag using a special sorting method. Its titanium content was low (TiO2: 40.81%). The perovskite was ground to a -325 mesh ratio of 90.5%.

[0111] 2. Oxidation roasting: The perovskite contains 4.51% vanadium. The perovskite is oxidized and roasted at 1050℃ for 1 hour. Oxygen is introduced during the roasting process to accelerate the oxidation of vanadium.

[0112] 3. Vanadium extraction by leaching: The roasted perovskite is leached in dilute sulfuric acid (c(H)+ Vanadium was extracted by leaching with a solution of 1 mol / L (liquid:solid ratio 6:1, mL / g), at a leaching temperature of 65℃ for 10 hours. After leaching, the mother liquor, containing approximately 3.8 g / L of vanadium, was used as the vanadium precipitate and was used to produce vanadium pentoxide. The leaching residue was washed and dried. The vanadium leaching rate was approximately 90.4%.

[0113] 4. Primary impurity removal:

[0114] A. Mix the vanadium-extracted perovskite with 98% concentrated sulfuric acid evenly for 15 minutes.

[0115] B. Subsequently, 20% waste sulfuric acid was added to initiate the reaction. The concentration of the reacting acid in the system was 93.5%, and the mass ratio of sulfuric acid to perovskite was 1.89:1. The reaction initially provided a heat source until the system temperature reached 160°C, after which it was stopped. During spontaneous reaction, the temperature rose to 213°C. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was then further aged at 180°C for 2 hours to ensure complete reaction with the sulfuric acid.

[0116] C. After aging, cool to below 60°C, add 2.3 times the mass of water to the solid and leach for 4 hours at a leaching temperature of 64°C. Solid titanium oxysulfate is converted into liquid titanium oxysulfate. After leaching, add flocculant and let it settle for 1 hour. Separate the upper clear liquid from the lower precipitate to obtain primary titanium-containing mother liquor and primary tailings. The primary tailings are washed with water until neutral.

[0117] 5. Secondary impurity removal:

[0118] A. Mix the dried primary tailings with 98% concentrated sulfuric acid evenly for 15 minutes.

[0119] B. Water was then added to initiate the reaction. The concentration of the reacting acid in the system was 92%, and the mass ratio of sulfuric acid to slag was 1.3:1. A heat source was provided at the beginning of the reaction until the system temperature reached 150°C, after which the reaction was stopped. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was further aged at 180°C for 2 hours. The titanium in the slag was further converted into titanium oxysulfate.

[0120] C. After maturation, cool to below 60℃, add 2.1 times the mass of water for 4 hours of leaching at 60℃, add flocculant and let settle for 1 hour. Separate the supernatant from the precipitate to obtain secondary titanium-containing mother liquor and secondary tailings. The obtained secondary titanium-containing mother liquor has a low iron content and does not require iron removal through crystallization. This process does not generate waste solids such as ferrous sulfate.

[0121] 6. Utilization of titanium-containing leaching solutions:

[0122] The titanium-containing liquid extracted from the two impurity removal processes was used as the leaching solution for the normal acid hydrolysis solid phase of titanium concentrate. During leaching, the titanium-containing liquid (the mass ratio of the primary titanium-containing mother liquor to the secondary titanium-containing mother liquor was 1:1) was added at 15% of the total leaching solution, with the remainder being primary water. The leaching temperature was 64℃, the leaching time was 4.5 h, and the liquid-to-solid ratio was 2.4:1 (mass ratio). After leaching, a titanium solution meeting production requirements was obtained, thus effectively utilizing the titanium in the perovskite, with a titanium recovery rate of approximately 92.5%.

[0123] 7. Utilization of Secondary Slag: After being washed with water to neutrality, the secondary slag mainly consists of sulfates, with a calcium recovery rate of 93.6%. The CaSO4·H2O content is 93.07%, SO3 content is 49.84%, and the pH value is 6.8. It is a high-quality raw material for producing cement retarder. The secondary slag has high utilization value, therefore no waste residue is discharged.

[0124] Table 8. Elemental content (ppm) of vanadium leaching mother liquor in Example 3

[0125] Fe V Ca Cr Mg Mn Al Ti 208 3807 950 1.47 870 85.2 905 595

[0126] Table 9. TiO2 content of primary and secondary titanium-containing mother liquors in Example 3.

[0127] sample <![CDATA[TiO2(g / L)]]> <![CDATA[H2SO4(g / L)]]> One-time titanium-containing mother liquor 78.25 327 Secondary titanium-containing mother liquor 52.04 195 Step 6: Immersion of titanium liquid 130 265

[0128] Table 10 Elemental analysis of primary and secondary tailings in Example 3 (%)

[0129]

[0130] Example 4

[0131] 1. Grinding: The perovskite used in the experiment was a product obtained from blast furnace slag using a special sorting method. Its titanium content was low (TiO2: 40.81%). The perovskite was ground to a -325 mesh ratio of 91%.

[0132] 2. Oxidation roasting: The perovskite contains 4.51% vanadium. The perovskite is oxidized and roasted at 850℃ for 2 hours. Oxygen is introduced during the roasting process to accelerate the oxidation of vanadium.

[0133] 3. Vanadium extraction by leaching: The roasted perovskite is leached in dilute sulfuric acid (c(H) + Vanadium was extracted by leaching with a solution of 1 mol / L (liquid:solid) at a liquid-to-solid ratio of 10:1 (mL / g), a leaching temperature of 75℃, and a leaching time of 12 h. After leaching, the mother liquor, containing approximately 2.3 g / L of vanadium, was used as the vanadium precipitate and was used to produce vanadium pentoxide. The leaching residue was washed and dried. The vanadium leaching rate was approximately 91%.

[0134] 4. Primary impurity removal:

[0135] A. Mix the vanadium-extracted perovskite with 93.5% concentrated sulfuric acid evenly for 20 minutes.

[0136] B. Subsequently, 20% waste sulfuric acid was added to initiate the reaction. The acid concentration of the system was 86%, and the mass ratio of sulfuric acid to perovskite was 1.95:1. A heat source was initially provided until the system temperature reached 150°C, after which the reaction was stopped. During spontaneous reaction, the temperature rose to 210°C. After 23 minutes of high-temperature reaction, the material was a thick slurry and had not solidified.

[0137] C. Cool the material to below 60°C, add 2.1 times the mass of water to the thick slurry material and leach for 4 hours at a leaching temperature of 63°C. After leaching, add flocculant and let it settle for 1 hour. Separate the upper clear liquid from the lower sediment to obtain primary titanium-containing mother liquor and primary tailings. Wash the primary tailings with water until neutral.

[0138] 5. Secondary impurity removal:

[0139] A. Mix the dried primary tailings with 98% concentrated sulfuric acid evenly for 20 minutes.

[0140] B. Subsequently, a certain amount of water was added to initiate the reaction. The concentration of the reacting acid in the system was 90%, and the mass ratio of sulfuric acid to slag was 1.25:1. A heat source was provided at the beginning of the reaction until the system temperature reached 150°C, after which the reaction was stopped. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was further aged at 180°C for 2 hours. The titanium in the slag was further converted into titanium oxysulfate.

[0141] C. After maturation, cool to below 60℃, add 1.5 times its weight of water for 4 hours of leaching at 63℃, add flocculant and let settle for 1 hour. Separate the supernatant from the precipitate to obtain secondary titanium-containing mother liquor and secondary tailings. The obtained secondary titanium-containing mother liquor has a low iron content and does not require iron removal through crystallization. This process does not generate waste solids such as ferrous sulfate.

[0142] 6. Utilization of titanium-containing leaching solutions:

[0143] The titanium-containing liquid extracted from the two impurity removal processes was used as the leaching solution for the normal acid hydrolysis solid phase of titanium concentrate. During leaching, the titanium-containing liquid (the mass ratio of the primary titanium-containing mother liquor to the secondary titanium-containing mother liquor was 1:1) accounted for 20% of the total leaching solution, with the remainder being primary water. The leaching temperature was 66℃, the leaching time was 4 hours, and the liquid-to-solid ratio was 2.5:1 (mass ratio). After leaching, a titanium solution meeting production requirements was obtained, thus effectively utilizing the titanium in the perovskite, with a titanium recovery rate of approximately 87%.

[0144] 7. Utilization of Secondary Slag: After being washed with water to neutrality, the secondary slag mainly consists of sulfates, with a calcium recovery rate of 92%. The CaSO4·H2O content is 88.40%, SO3 content is 49.17%, and the pH value is 6.5. It is a high-quality raw material for producing cement retarder. The secondary slag has high utilization value and produces no waste residue.

[0145] Table 11 Elemental content (ppm) of vanadium leaching mother liquor in Example 4

[0146] Fe V Ca Cr Mg Mn Al Ti 78 2308 430 0.95 305 29.6 258 304

[0147] Table 12 shows the TiO2 content of the primary and secondary titanium-containing mother liquors in Example 4.

[0148] sample <![CDATA[TiO2(g / L)]]> <![CDATA[H2SO4(g / L)]]> One-time titanium-containing mother liquor 60.28 233 Secondary titanium-containing mother liquor 39.10 201 Step 6: Immersion of titanium liquid 135 266

[0149] Table 13 Elemental analysis of primary and secondary slag in Example 4 (%)

[0150]

[0151] Comparative Example 1

[0152] 1. Grinding: The perovskite used in the experiment was a product obtained from blast furnace slag using a special sorting method. Its titanium content was low (TiO2: 40.81%). The perovskite was ground to a -325 mesh ratio of 91%.

[0153] 2. Oxidation roasting: The perovskite contains 4.51% vanadium. The perovskite is oxidized and roasted at 850℃ for 2 hours. Oxygen is introduced during the roasting process to accelerate the oxidation of vanadium.

[0154] 3. Vanadium extraction by leaching: The roasted perovskite is leached in dilute sulfuric acid (c(H) + Vanadium was extracted by leaching with a solution of 1 mol / L (liquid:solid) at a liquid-to-solid ratio of 10:1 (mL / g), a leaching temperature of 75℃, and a leaching time of 12 h. After leaching, the mother liquor, containing approximately 2.3 g / L of vanadium, was used as the vanadium precipitate and was used to produce vanadium pentoxide. The leaching residue was washed and dried. The vanadium leaching rate was approximately 91%.

[0155] Conventional acid removal for purification:

[0156] 4. Primary impurity removal:

[0157] A. Mix the vanadium-extracted perovskite with 98% concentrated sulfuric acid evenly for 15 minutes.

[0158] B. Subsequently, 20% waste sulfuric acid was added to initiate the reaction. The concentration of the reacting acid in the system was 93.5%, and the mass ratio of sulfuric acid to perovskite was 1.5:1. A heat source was initially provided until the system temperature reached 160°C, after which the reaction was stopped. During spontaneous reaction, the temperature rose to 215°C. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was then further aged at 180°C for 2 hours to ensure complete reaction with the sulfuric acid.

[0159] C. After aging, cool to below 60°C, add water to the solid and leach for 4 hours to convert solid titanium oxysulfate into liquid titanium oxysulfate. After leaching, add flocculant and settle for 1 hour. Separate the upper clear liquid from the lower precipitate to obtain a primary titanium-containing mother liquor and a primary tailings. The primary tailings are washed with water until neutral.

[0160] 5. Secondary impurity removal:

[0161] A. Mix the dried primary tailings with 90% concentrated sulfuric acid evenly for 15 minutes.

[0162] B. Water was then added to initiate the reaction. The concentration of the reacting acid in the system was 85%, and the mass ratio of sulfuric acid to slag was 1.55:1. After several minutes of high-temperature reaction, the material solidified into a steel-gray solid phase. The solid phase was further aged at 180°C for 2 hours. The titanium in the slag was further converted into titanium oxysulfate.

[0163] C. After maturation, cool to below 60°C, add water and soak for 4 hours, then add flocculant and settle for 1 hour. Separate the upper clear liquid from the lower precipitate to obtain secondary titanium-containing mother liquor and secondary tailings.

[0164] The first titanium leaching solution contained 42.89 g / L TiO2, and the second titanium leaching solution contained 30.15 g / L TiO2. The titanium recovery rate was approximately 71%, which was low with conventional acid hydrolysis parameters for impurity removal. The tailings were mainly composed of sulfates, with a CaSO4·H2O content of 69%. The CaSO4·H2O content was low, resulting in low utilization value, while the content of other impurities remained relatively high.

[0165] Table 14 shows the TiO2 content of the titanium-containing mother liquor in Comparative Example 1.

[0166] sample <![CDATA[TiO2(g / L)]]> <![CDATA[H2SO4(g / L)]]> One-time titanium-containing mother liquor 42.89 221 Secondary titanium-containing mother liquor 30.15 195

[0167] Table 15 Elemental analysis of primary and secondary slags in Comparative Example 1 (%)

[0168]

[0169] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention. Clearly, those skilled in the art can make various alterations and modifications to the invention without departing from its spirit and scope. Thus, if these modifications and modifications of the invention fall within the scope of the claims and their equivalents, the invention is also intended to include these modifications and modifications.

Claims

1. A method for the clean extraction and utilization of valuable elements in perovskite, characterized in that, Includes the following steps: S1. Oxidative roasting: The ground and sieved perovskite powder is directly oxidized and roasted at 800~1080℃, with oxygen introduced during the roasting process; the elemental content of the perovskite, by mass fraction, is: TiO2 35~45%, CaO 25~35%, Fe2O3 <0.5%, V2O5 3~5%; S2. Vanadium extraction by leaching: The roasted perovskite is leached in an acid solution of 0.4~1 mol / L at a leaching temperature of 60~80℃. After leaching, solid-liquid separation is performed to obtain vanadium-precipitated liquid and leaching residue. S3. Primary impurity removal: The leaching residue is mixed evenly with concentrated sulfuric acid of 93-98% by mass, and then dilute sulfuric acid or water is added to initiate the reaction. Ensure that the total sulfuric acid mass fraction in the reaction liquid is above 85% and the liquid-solid mass ratio is ≥1.8:

1. The reaction starts by providing a heat source until the system reaction temperature reaches 140-160℃ and then stops. If the material solidifies, it is then aged at 170-190℃ for 1.5-2.5 hours after solidification. If the material does not solidify, the total reaction time is controlled to be 20-40 minutes. After the reaction, water was added for leaching, followed by sedimentation, to obtain a titanium-containing mother liquor and a tailings. S4. Secondary impurity removal: The primary tailings are mixed evenly with concentrated sulfuric acid of 93-98% by mass, and then dilute sulfuric acid or water is added to initiate the reaction. The total sulfuric acid mass fraction in the reaction liquid is kept above 90%, and the liquid-solid mass ratio is (1.0-1.5):

1. The reaction begins to provide a heat source and stops when the system reaction temperature reaches 140-160℃. After the material solidifies, it is further matured at 170-190℃ for 1-2 hours. After the reaction, water was added for leaching, followed by sedimentation, to obtain a secondary titanium-containing mother liquor and a secondary tailings. S5. Add a certain amount of primary water to the primary titanium-containing mother liquor obtained in step S3 and the secondary titanium-containing mother liquor obtained in step S4 to make a leaching solution for the normal titanium concentrate acid hydrolysis solid phase. The amount of primary titanium-containing mother liquor and secondary titanium-containing mother liquor added during leaching is 5-20% of the total mass of the leaching solution.

2. The method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, The perovskite powder in step S1 contains ≥90% -325 mesh particles by mass.

3. The method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, The oxidation calcination time in step S1 is 0.5~2h.

4. The method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, The liquid-to-solid ratio for leaching in step S2 is (4~10):1 mL / g, and the leaching time is 6~12h.

5. The method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, The vanadium precipitate liquid obtained in step S2 is used to produce vanadium pentoxide products.

6. The method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, The secondary tailings obtained in step S4 are washed with water until neutral to obtain calcium sulfate product.

7. The preparation method of the method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, Flocculant is added during sedimentation in steps S3 and S4.

8. The preparation method of the method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, In step S3, the mass ratio of the leaching solution to the ore is 2~2.3:1, all the leaching solution is made from primary water, the leaching temperature is 60~65℃, and the leaching time is 3~5h. In step S4, the liquid-to-ore mass ratio for water leaching is 1.5~2.1:1, all leaching solutions are made from primary water, the leaching temperature is 60~65℃, and the leaching time is 3~5h.

9. The preparation method of the method for clean extraction and utilization of valuable elements in perovskite as described in claim 1, characterized in that, In step S5, the leaching liquid-to-ore mass ratio is 2.4-2.5:1, the leaching temperature is 64-66℃, and the leaching time is 4-4.5h.

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