Calcium-titanium compound as well as preparation method and application thereof

Abstract

The invention discloses a calcium-titanium compound as well as a preparation method and application thereof, and belongs to the technical field of application of titanium-containing slag. The calcium-titanium compound comprises calcium-titanium oxide, the surface and the interior of the calcium-titanium compound are both provided with pore structures, the specific surface area is 0-30 m < 2 > / g, the pore volume is larger than 0.0005 cm < 3 > / g, and the pore diameter of the pore structures is larger than 5 nm. The preparation method comprises the following steps: adding a modifier into molten titanium-containing slag for mineral reconstruction to obtain reconstructed slag particles, and carrying out leaching treatment on the reconstructed slag particles to obtain an extract, namely the calcium-titanium compound. The calcium-titanium compound provided by the invention has wide application in the field of preparation of titanium-containing products.

Description

Technical Field

[0001] This invention belongs to the field of titanium-containing slag application technology, specifically relating to a calcium-titanium composite, its preparation method and application. Background Technology

[0002] Titanium, as an important strategic metal, plays an irreplaceable role in numerous fields such as chemical engineering, metallurgy, and aerospace. The market for titanium-containing products is vast, and demand continues to grow steadily. Among these, titanium oxide is one of the most widely used titanium-containing products, extensively used in industries such as coatings, plastics, papermaking, and inks. Developing low-cost alternatives to titanium-containing products, as well as high-purity calcium titanium oxide and related high-end products, is of great significance and promise.

[0003] Nearly 100 million tons of titanium-containing slag are generated from smelting, yet this has not been fully utilized. The inventors, dedicated to research in the utilization of titanium-containing slag resources, disclosed a method for preparing CaTiO3 composite materials using slowly cooled titanium-containing blast furnace slag in their Chinese patent application (No. 201210004204.3, published on July 18, 2012). The inventors mixed titanium-containing blast furnace slag with a certain amount of NaNO3 at high temperature for thermal modification, converting insoluble silicates into soluble ones. After removal by hot water washing, the filter residue was acidified with a 5wt% dilute hydrochloric acid solution, and then filtered and washed with water to remove components such as Al, Fe, and Mg, resulting in a calcium titanium oxide content of 87%. However, this method only modifies and reconstructs solid cold slag and cannot be directly used for mineral reconstruction of molten titanium-containing blast furnace slag. Furthermore, NaNO3 as an additive poses safety risks in industry, and the purity of the subsequent calcium titanium oxides needs to be improved to obtain higher purity and higher value calcium titanium oxides.

[0004] Furthermore, high-purity calcium titanium oxides not only serve as alternative raw materials for the production of titanium-containing products, but also play a crucial role in high-end applications such as electronic ceramics, microwave absorbing materials, and sensors due to their excellent optical and electrical properties and chemical stability. Currently, the market demand for high-purity calcium titanium oxides is showing a continuous growth trend. However, the existing process of "chemical co-precipitation-high-temperature calcination"—using titanium tetrachloride and calcium nitrate as raw materials, co-precipitating with oxalic acid or ammonium carbonate to obtain a precursor, and then calcining at 1100–1200℃ for 4–6 hours to obtain calcium titanium oxides—is not only expensive in terms of raw materials, but also... - NO3 - Residues lead to equipment corrosion and nitrogen oxide emissions. As a result, the complex preparation process and high production cost of existing high-purity calcium titanium oxides have resulted in high market prices, which seriously limits their large-scale promotion and application in high-end application fields.

[0005] Titanium-containing blast furnace slag, as an important secondary titanium resource, contains calcium titanium oxides with significant utilization value. However, less than half of the titanium in the slag exists as calcium titanium oxides within the perovskite, and these oxides crystallize in a fine dendritic form. Most of the titanium is dispersed within various minerals such as titanium-bearing diopside and zeolite. Direct extraction of these calcium titanium oxides is not only technically challenging but also costly. Therefore, the resource utilization of titanium-containing slag faces numerous difficulties.

[0006] Firstly, selective enrichment and phase separation of titanium components are difficult: Titanium-containing slag has a high Ti content, but it is dispersed in multiple phases such as perovskite, titanium-bearing diopside, and zeolite. The Ti grain size is small, only about 10-15 μm, making resource utilization difficult. Even after modification and subsequent acid leaching to remove impurities, the highest yield is only about 45% titanium dioxide-containing calcium-titanium oxide, leaving considerable room for improvement in high-purity calcium-titanium composite oxides. Furthermore, the high acid consumption for titanium enrichment (low solid-liquid ratio) hinders cost control in large-scale production and is environmentally unfriendly. Therefore, despite some progress in existing technologies for the resource utilization of titanium-containing slag, the cost-effectiveness ratio is still not well-matched, making high-value-added large-scale utilization difficult.

[0007] Secondly, the thermal energy of molten titanium-containing slag is difficult to utilize, and it even affects the remodeling and modification of titanium-containing slag:

[0008] The modifier has poor dispersibility in molten titanium-containing slag: Since titanium-containing slag is a short slag, it has high viscosity and poor fluidity in the molten state. Moreover, at the high temperature of molten titanium-containing slag, the added modifier is prone to dust generation, causing uneven mixing and other problems, which affect the mineral modification results.

[0009] Controlling the uniformity of temperature and composition fields within a large electric furnace is a challenging engineering problem: adding modifiers or injecting oxidants into molten titanium-containing slag can easily cause temperature fluctuations, and mineral modification is extremely critical for temperature control.

[0010] Therefore, how to rationally utilize the high-temperature thermal energy during the slag discharge process of metallurgical furnaces is the key to the resource utilization of such difficult-to-treat metallurgical slag.

[0011] In summary, in order to maximize the utilization of titanium-containing slag resources and make it suitable for industrial production, there is an urgent need to find a calcium-titanium composite and its preparation method and application. Summary of the Invention

[0012] 1. The problem to be solved

[0013] One of the objectives of this invention is to provide a calcium-titanium composite that allows for the control of the specific surface area, pore volume, and pore size of the surface pore structure.

[0014] Another objective of this invention is to provide a method for preparing a calcium-titanium composite, enabling direct mineral reconstruction of molten titanium-containing slag, which is beneficial for industrial production. Further applications of the aforementioned calcium-titanium composite are also provided.

[0015] 2. Technical Solution

[0016] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0017] A first aspect of the present invention provides a perovskite composite comprising perovskite oxide, having a porous structure on both the surface and the interior, wherein:

[0018] Specific surface area is 0–30 m² 2 / g, preferably 10-30m 2 / g, preferably 10-15m 2 / g, preferably 0.45~10m 2 / g;

[0019] The pore volume is greater than 0.0005 cm³. 3 / g, preferably 0.0005~0.05cm 3 / g, preferably 0.0005~0.04cm 3 / g, preferably 0.02~0.04cm 3 / g;

[0020] The pore size of the pore structure is greater than 5 nm, preferably 5–12 nm, more preferably 11–19 nm, and more preferably 18–25 nm.

[0021] A calcium-titanium composite comprising calcium-titanium oxide, said calcium-titanium oxide being obtained by mineral phase reconstruction and leaching treatment of molten titanium-containing slag at a temperature not lower than 1300°C; its surface and interior both possess a porous structure, wherein:

[0022] Specific surface area is 0–30 m² 2 / g, preferably 10-30m 2 / g, preferably 10-15m 2 / g, preferably 0.45~10m 2 / g;

[0023] The pore volume is greater than 0.0005 cm³. 3 / g, preferably 0.0005~0.05cm 3 / g, preferably 0.0005~0.04cm 3 / g, preferably 0.02~0.04cm 3 / g;

[0024] The pore size of the pore structure is greater than 5 nm, preferably 5–12 nm, more preferably 11–19 nm, and more preferably 18–25 nm.

[0025] With the above technical solution adopted, the perovskite composite of this application is a porous material, and the pore volume, pore size, and specific surface area are controlled within the above-mentioned ranges:

[0026] On the one hand, it has low diffusion resistance in gases or liquids, making it particularly suitable for catalytic processes involving macromolecular reactants; on the other hand, its suitable specific surface area reduces adsorption sites for non-target substances, avoids excessive competition of reactants on the surface, improves the selectivity of the target reaction, and reduces byproducts. For example, in the cathode of a fuel cell, porous perovskite composites can accelerate the mass transfer efficiency of the oxygen reduction reaction.

[0027] On the other hand, the perovskite composite of this application has good mechanical and thermal stability. The suitable specific surface area means suitable pore walls and dense skeleton, excellent compressive strength, and is not easily deformed under high temperature or high pressure environment. It also has good air permeability, which is conducive to its application as a support structure, such as electrode support for solid oxide fuel cells and high-end building materials. At the same time, it can inhibit particle agglomeration, which is conducive to its use as a support structure and to maintaining stable activity of catalysts during recycling, thus extending cycle life.

[0028] Finally, it is worth mentioning that the pore size of this invention can be adjusted. While ensuring the mass transfer effect, the pore volume formed by the internal pores of the perovskite composite in this application provides active sites. The synergistic effect of the two has broad application prospects.

[0029] As one possible implementation scheme, a section of slag has a specific surface area distribution of 9–29 m². 2 / g, total pore volume distribution is 0.02–0.05 cm³. 3 / g, with a pore size distribution of 5–12 nm.

[0030] As one possible implementation scheme, the secondary slag has a specific surface area distribution of 6–15 m². 2 / g, total pore volume distribution is 0.02–0.05 cm³. 3 / g, with a pore size distribution of 11–20 nm.

[0031] As one possible implementation scheme, the three-stage slag has a specific surface area distribution of 0.45–10 m². 2 / g, total pore volume distribution is 0.0005–0.04 cm³. 3 / g, with a pore size distribution of 5–25 nm.

[0032] As one possible implementation, the calcium titanium oxide content in the calcium titanium composite is greater than 30%, preferably greater than 50%, preferably greater than 70%, preferably greater than 80%, preferably greater than 90%, preferably greater than 95%, preferably greater than 98%, and preferably 99.52%.

[0033] As one possible implementation, the titanium oxide content in the calcium-titanium composite is greater than 40%, preferably 40-60%.

[0034] A second aspect of the present invention provides a possible method for preparing the above-mentioned perovskite composite, comprising the following steps:

[0035] S1. Mineral Reconstruction: A modifier is added to the molten titanium-containing slag, or a modifier is added to the molten titanium-containing slag while an oxidizing gas is introduced, and mineral phase reconstruction is carried out at a temperature not lower than 1300℃, preferably 1300℃~1800℃, 1350℃~1500℃, 1450℃~1500℃, 1600℃~1700℃, preferably 1350℃, 1400℃, 1460℃, 1500℃, 1620℃, 1700℃. After cooling, reconstructed slag is obtained, which is then crushed and / or ground to obtain reconstructed slag particles.

[0036] S2. Leaching treatment: The reconstructed slag particles obtained in step S1 are subjected to leaching treatment to obtain the leachate, namely the calcium-titanium composite.

[0037] Using the above technical solution, this application directly reconstructs the minerals in the molten titanium-containing slag. In the molten state, each component exists as ions or complex ion clusters. During cooling, depending on the cooling rate, different ordered crystalline minerals or disordered amorphous substances (such as glassy substances) are formed. Therefore, it is necessary to control the slag discharge temperature to be no lower than 1300℃, at which point the precipitation of calcium titanium oxides reaches its maximum. More importantly, at this temperature, although the slag viscosity is relatively high, it can still be discharged; otherwise, the slag will solidify in the refractory lining of the electric furnace, and the reconstructed slag will damage the furnace lining. This application uses an unconventional method to improve the purity of the calcium titanium composite, allowing for controllable adjustment of the specific surface area and pore size over a wide range.

[0038] As one possible implementation, in step S1, the oxidizing gas includes, but is not limited to, CO2, O2 or air, to oxidize the low-valence titanium in the slag, and at the same time has the function of stirring to improve the slag reaction kinetics and mass transfer conditions.

[0039] As one possible implementation, in step S1, the mass of the modifier is 5% to 40% of the mass of the titanium-containing slag, preferably 15% to 40% of the mass of the titanium-containing slag, preferably 15% to 35% of the mass of the titanium-containing slag, preferably 15% to 28% of the mass of the titanium-containing slag, preferably 28% to 35% of the mass of the titanium-containing slag, preferably 28% to 40% of the mass of the titanium-containing slag, and preferably 35% to 40% of the mass of the titanium-containing slag.

[0040] As one possible implementation, in step S1, the titanium-containing slag includes, but is not limited to, one or more of the following: titanium-containing blast furnace slag, ilmenite, a mixture of high-titanium slag and calcium-containing silicate solid waste (natural ore), ilmenite and calcium-containing silicate solid waste (or minerals), and titanium slag (or titanium ore) and calcium-containing silicate solid waste (or minerals). For example, the TiO2 content in the raw titanium-containing blast furnace slag is approximately 20% to 22%.

[0041] As one possible implementation, in step S1, the modifier is a sodium- or potassium-containing compound, preferably a sodium- or potassium-containing compound that easily generates oxidizing gases, including but not limited to organic compounds and inorganic compounds. The effective components of the organic compound are one or more of sodium humate, potassium sodium humate, sodium acetate, potassium acetate, sodium benzoate, and potassium benzoate. The effective components of the inorganic compound are one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, sodium nitrate, and potassium nitrate.

[0042] When using the above technical solution, the modifier is preferably a component that can generate oxidizing gas at high temperatures. For example, sodium humate will directly decompose into Na at temperatures above 400°C. + CO2, Na + The process breaks the silicon-oxygen bonds in insoluble silicate minerals and promotes the formation of soluble Na silicate minerals. When benzoate is added to alkaline molten titanium-containing slag, it releases CO2 at the high temperature of mineral reconstruction. Acetate decomposes into carbonate and acetone at temperatures above 400°C. Acetone is completely oxidized to CO2 and water under high temperature and oxygen-rich conditions. At the same time, carbonate releases CO2 at the high temperature of mineral reconstruction. CO2 plays a role similar to airflow stirring in the slag system, and reduces the viscosity of the slag system, resulting in good kinetic conditions and a complete reaction.

[0043] Among them, acetate is superior to carbonate / bicarbonate as a modifier. Firstly, carbonate is in powder form and is loosely packed, while acetate usually exists in the form of crystalline particles. The particles are larger and have smooth surfaces, and their density is greater than that of carbonate. When fed, they are easy to settle due to gravity and are not easy to suspend in the air to form dust. At the same time, acetate has strong hygroscopicity and is easy to deliquesce in humid environments. After the surface is slightly dissolved, a liquid film is formed, which can also inhibit the diffusion of dust.

[0044] However, when sodium hydroxide, potassium hydroxide, sodium nitrate, or potassium nitrate are used as modifiers, mineral reconstruction can also be achieved by introducing oxidizing gas.

[0045] As one possible implementation, in step S1, the modifier is a blocky heavy material, a granulated lightweight material, or a cored wire (the modifier is encapsulated within the shell).

[0046] To address the issue of dust generation when feeding molten titanium-containing slag into the above-mentioned technical solution, the modifier is pretreated using a heavy-duty process or granulated lightweight materials to achieve higher density. Specifically:

[0047] ①The pretreatment steps of acetate are as follows: First, the acetate is heated at 120℃~180℃ to dehydrate and convert it into anhydrous acetate; the anhydrous acetate is heated to melt (sodium acetate melting point 324℃), atomized and then rapidly cooled to form high-density spherical acetate particles.

[0048] ② The pretreatment steps for benzoate are as follows: first, benzoate is dissolved in hot water, decolorized with activated carbon, and cooled to crystallize, thereby obtaining large-particle crystals and reducing intercrystalline porosity; powdered benzoate is then formed into dense tablets by high pressure molding (>50MPa) using a roller press, increasing the bulk density by 30% to 50%.

[0049] ③ The pretreatment steps for carbonates or bicarbonates are as follows:

[0050] Carbonate or bicarbonate powders are converted into blocky heavy soda ash carbonates or heavy bicarbonates through hydration crystallization, calcination, and compaction heavyification processes.

[0051] or

[0052] Carbonates or bicarbonates are mixed with a binder (e.g., PVA) and wet-granulated to obtain granulated carbonates or bicarbonates, wherein the binder (e.g., PVA) accounts for less than 1% of the weight of the carbonates or bicarbonates. In existing technologies, the binder typically accounts for more than 2% of the weight; however, in this application, it is used as a modifier in molten titanium-containing slag, eliminating the need for a binder to ensure the strength of the granulated particles. Only dust generation during the addition of carbonates or bicarbonates needs to be avoided, and the amount of binder can be controlled to within 1% of the weight of the carbonates or bicarbonates. Furthermore, the high-temperature decomposition of PVA and other components releases CO2, which also has a beneficial effect on the oxidation of low-valence "Ti" to high-valence "Ti".

[0053] ④ The pretreatment steps for strong alkalis are as follows: molten strong alkali is scraped through a roller to form caustic soda flakes, or sprayed to granulate into spherical particles.

[0054] ⑤ The pretreatment steps for nitrates are as follows: after the nitrate melt is atomized, it is rapidly cooled to form dense spherical nitrate particles.

[0055] As one possible implementation, in step S1, to further avoid dust generation from the modifier, the feeding pressure is negative. Alternatively, the hot slag can be directly fed into the plasma furnace from the slag outlet, or it can be transferred to an iron or titanium slag pot before being fed into the plasma furnace. The plasma furnace is preferably a 100kVA plasma furnace.

[0056] As one possible implementation, in step S1, the molten titanium-containing slag is reconstructed at a temperature not lower than 1300℃, preferably 1300℃~1800℃, 1350℃~1500℃, 1450℃~1500℃, 1600℃~1700℃, and more preferably 1400℃, 1460℃, 1500℃, 1620℃, and 1700℃ (after the feeding is completed, the slag temperature is measured to be about 1600℃ using an infrared thermometer, and the power is cut off after about 5 minutes of constant current and voltage).

[0057] As one possible implementation, in step S2, a one- to three-stage leaching process is used to obtain a calcium-titanium composite, wherein the calcium-titanium oxide content in the calcium-titanium composite is greater than 80%.

[0058] As one possible implementation, step S2 involves a leaching process, the steps of which are as follows:

[0059] The reconstituted slag particles are placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid is less than or equal to 0; the purpose of the first-stage acid leaching is to remove soluble silicates from the reconstituted slag.

[0060] As one possible implementation, the first-stage acid is a mixture of one or more of HCl, HF, HBr, HI, and HNO3, and the mass ratio of the reconstituted residue particles to the volume of the first-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, preferably 0-60℃, preferably 0-50℃, preferably 0-40℃, preferably 10-40℃, preferably 20-35℃, preferably 20℃, 25℃, 30℃, 35℃, and 80℃; the leaching reaction time is 0.5-2 h.

[0061] As a possible solution, when the leaching system temperature is 0°C or below, i.e. in an ice-water (or brine) bath environment, the ratio of the mass of the reconstituted slag particles to the volume of a first-stage acid is 1 g:(5-10 ml), which can increase the solid-liquid ratio and reduce the acid consumption for titanium enrichment in existing technologies.

[0062] As one possible implementation, in order to further strip away the unreconstructed insoluble silicates, step S2 involves at least two leaching processes to obtain the leachate, namely the calcium-titanium complex, which includes at least one leaching process containing F salt or F acid.

[0063] The applicant attempted to prepare a composite leachate by mixing an F-containing salt into an acid solution. However, this mixing process generates HF, which poses a significant hazard and is detrimental to large-scale industrial production. Therefore, it is essential that the acid and the F-containing salt be separated for the acid leaching treatment in this application.

[0064] As one possible implementation, step S2 includes two leaching processes:

[0065] S21, First-stage acid leaching: The reconstituted slag particles are placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid is less than or equal to 0; the purpose of the first-stage acid leaching is to remove soluble silicates from the reconstituted slag;

[0066] S22, Two-stage leaching: The first-stage leachate is placed in a leachate containing F salt or F acid, and after filtration, washing and drying, a second-stage leachate is obtained; wherein, the effective components of the leachate include, but are not limited to, HF and NH4HF2 solution.

[0067] As one possible implementation, in step S21, one or more of the first-stage acid HCl, HF, HBr, HI, and HNO3 are mixed, and the mass ratio of the reconstituted residue particles to the volume of the first-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, preferably 0-60℃, preferably 0-50℃, preferably 0-40℃, preferably 10-40℃, preferably 20-35℃, preferably 20℃, 25℃, 30℃, 35℃, and 80℃; the leaching reaction time is 0.5-2 h.

[0068] As a possible implementation, in step S21, when the leaching system temperature is 0°C or below, i.e. in an ice-water (or brine) bath environment, the ratio of the mass of the reconstituted slag particles to the volume of a first-stage acid is 1 g:(5-10 ml), which can increase the solid-liquid ratio and reduce the acid consumption for titanium enrichment in the prior art.

[0069] As one possible implementation, in step S22, the mass concentration of the effective component in the leachate is 0.5% to 10%. For example, when the leachate is an NH4HF2 solution, the mass concentration of the NH4HF2 solution is 0.5% to 10%, and the mass ratio of a portion of the leachate to the volume of the NH4HF2 solution is 1 g:(5 to 25 ml). The leaching system temperature is 0 to 80°C, preferably 0 to 60°C, preferably 0 to 50°C, preferably 0 to 40°C, preferably 10 to 40°C, preferably 20 to 35°C, preferably 20°C, 25°C, 30°C, 35°C, or 80°C, and the leaching reaction time is 0.5 to 2 hours.

[0070] As one possible implementation, step S2 includes three leaching processes, namely:

[0071] S21, First-stage acid leaching: The reconstituted slag particles are placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid is less than or equal to 0; the purpose of the first-stage acid leaching is to remove soluble silicates from the reconstituted slag;

[0072] S22, Two-stage leaching: The first-stage leachate is placed in a leachate containing F salt or F acid, and after filtration, washing and drying, a second-stage leachate is obtained; wherein, the effective components of the leachate include, but are not limited to, HF and NH4HF2 solution.

[0073] S23, Three-stage acid leaching: The two-stage extract is placed in a three-stage acid, and after filtration, washing and drying, a three-stage extract, namely a calcium-titanium complex, is obtained; wherein, the pH value of the three-stage acid is greater than 0, preferably the pH value of the three-stage acid is 0.5 or 1.0.

[0074] As one possible implementation, in step S21, the first-stage acid is one or more of HCl, HF, HBr, HI, and HNO3, and the mass ratio of the reconstituted residue particles to the volume of the first-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, preferably 0-60℃, preferably 0-50℃, preferably 0-40℃, preferably 10-40℃, preferably 20-35℃, preferably 20℃, 25℃, 30℃, 35℃, or 80℃, and the leaching reaction time is 0.5-2 h.

[0075] As a possible solution, when the leaching system temperature is 0°C or below, i.e. in an ice-water (or brine) bath environment, the ratio of the mass of the reconstituted slag particles to the volume of a first-stage acid is 1 g:(5-10 ml), which can increase the solid-liquid ratio and reduce the acid consumption for titanium enrichment in existing technologies.

[0076] As one possible implementation, in step S22, the mass concentration of the effective component in the leachate is 0.5% to 10%. For example, when the leachate is an NH4HF2 solution, the mass concentration of the NH4HF2 solution is 0.5% to 10%, and the mass ratio of a portion of the leachate to the volume of the NH4HF2 solution is 1 g:(5 to 25 ml). The leaching system temperature is 0 to 80°C, preferably 0 to 60°C, preferably 0 to 50°C, preferably 0 to 40°C, preferably 10 to 40°C, preferably 20 to 35°C, preferably 20°C, 25°C, 30°C, 35°C, or 80°C, and the leaching reaction time is 0.5 to 2 hours.

[0077] As one possible implementation, in step S23, the three-stage acid is one or a mixture of HCl, HF, HBr, HI, and HNO3. The mass ratio of the two-stage extract to the volume of the three-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, preferably 0-60℃, preferably 0-50℃, preferably 0-40℃, preferably 10-40℃, preferably 20-35℃, preferably 20℃, 25℃, 30℃, 35℃, and 80℃, and the leaching reaction time is 0.5-2 h.

[0078] It should be noted that in the second-stage leaching, a small amount of unconverted insoluble silicates are converted into insoluble fluoride salts (such as MgF2) and readily soluble silicon fluoride:

[0079] MgF2 is a sparingly soluble substance (Ksp(25℃)=5.16×10 -11) It has a stable crystal structure and reacts slowly with dilute acids at room temperature. F - With H + It combines to form HF (a weak acid, pKa = 3.18), but the low solubility of MgF2 limits its dissociation rate, requiring strong acid or high temperature conditions to promote the reaction. Increasing the temperature promotes dissolution and ion diffusion; concentrated acid increases H2O. + Concentration shifts the equilibrium to the right, so a strong acid and an 80°C constant temperature water bath are preferred.

[0080] It should be noted that the first and / or second and / or third stage leachates of this application contain silicic acid and magnesium aluminum metal compounds, which are used to produce silica, magnesium aluminum refractory materials (such as magnesium aluminum spinel), etc.

[0081] The third aspect of the present invention provides the application of the above-mentioned calcium-titanium composite in the production and preparation of titanium alloys, sponge titanium, titanium tetrachloride, ceramic materials, welding materials, electronic materials, semiconductor materials, dielectric materials, catalysts (including but not limited to coal combustion sulfur and nitrogen fixation and combustion catalysts) and their carriers, coating materials, thermoelectric materials, microwave absorbing materials and other titanium-containing products.

[0082] The perovskite oxides obtained in this invention have tunable specific surface area, pore size, and pore volume over a wide range. Although perovskite composites with suitable specific surface areas are limited in applications such as catalysis and sensing due to fewer surface active sites and weak adsorption capacity, they are actually more advantageous in certain specific scenarios:

[0083] (1) Photovoltaic devices: Small surface area means fewer surface defects and fewer grain boundaries, which can effectively suppress ion migration and moisture erosion and improve long-term stability.

[0084] (2) Photodetector: Dense thin film can reduce leakage current caused by surface defects and improve signal-to-noise ratio.

[0085] (3) Catalyst: The low specific surface area calcium-titanium composite has a stable structure at high temperature and is suitable for strongly alkaline environments.

[0086] (4) Catalytic support: The low specific surface area calcium-titanium composite is used as the core active phase and can be loaded on a high specific surface area support (such as ZrO2, CeO2) to balance activity and stability.

[0087] (5) Anti-poisoning fuel cell electrode: Dense calcium titanium composite electrode can reduce the adsorption of impurity gases (such as SO2) and avoid catalyst poisoning.

[0088] 3. Beneficial effects

[0089] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0090] (1) In the preparation method of the calcium-titanium composite of the present invention, although the two main minerals, soluble silicate and enriched calcium-titanium oxide, are inter-embedded to a certain extent in the reconstructed slag particles obtained by mineral reconstruction, the average particle size of the enriched calcium-titanium oxide is increased from about 10 micrometers in the original titanium-containing blast furnace slag to about 30 micrometers. Therefore, the monomer dissociation of the two does not need to be less than 30 micrometers as in traditional physical (flotation, gravity separation or magnetic separation, etc.) separation.

[0091] Furthermore, it is worth noting that while existing technologies have enabled the enrichment and growth of perovskite oxides to over 30 micrometers, the significant differences in physical properties between artificially enriched perovskite oxides and natural perovskite oxides result in very low physical sorting efficiency. Experimental data (leaching sample composition) indicate that by simply crushing the reconstructed slag particles to no larger than 80 mesh (approximately 100 micrometers), the subsequent leaching solution can easily dissolve the soluble silicates already formed and encapsulated or embedded in the enriched perovskite oxides (due to favorable mass transfer kinetics). In other words, the soluble silicates inside the reconstructed slag can also be leached, dissolved, and stripped away.

[0092] Simultaneously through Na + and / or K + It can inhibit the formation of insoluble silicates and form eutectic compounds with silicon dioxide: Na + / K + It breaks the silicon-oxygen bonds in insoluble silicate minerals and promotes the formation of soluble Na or K silicate minerals. + K + Both methods inhibit SiO2 polymerization and reduce the amount of sparingly soluble silicates (such as CaSiO2) by increasing the basicity of the slag. 3) Formation; with silicate (SiO4) 4-) It forms soluble complexes (such as Na2SiO3, K2SiO3, etc.), reducing the tendency of silica molecules to aggregate.

[0093] (2) In the preparation method of the calcium-titanium composite of the present invention, the extraction and application of calcium-titanium oxides are realized through leaching process, and the grade of calcium-titanium oxides can even reach 99.52%.

[0094] (3) In the preparation method of the calcium titanium composite of the present invention, after the three-stage acid leaching and peeling, the calcium titanium oxide obtained by filtration, washing and drying has no silicon gel coating on the surface compared with the previous patent technology, and can exert its performance to a certain extent.

[0095] (4) In the preparation method of the calcium-titanium composite of the present invention, the raw materials used are titanium-containing slag with wide sources, including but not limited to titanium-containing blast furnace slag, ilmenite, a mixture of high titanium slag and calcium silicate solid waste (natural mineral), ilmenite + calcium silicate solid waste (or mineral), titanium slag (or titanium ore) + calcium silicate solid waste (or mineral), one or more of these, which have low cost and do not generate secondary pollution in the whole process, thus meeting environmental protection requirements.

[0096] (5) In the preparation method of the calcium-titanium composite of the present invention, the modifiers with effective components being acetate, benzoate, carbonate, bicarbonate, strong base salt, and nitrate are used. Among them, acetate, benzoate, carbonate, and bicarbonate are better than NaNO3 as alkaline-thermal modifiers. Because the NO gas produced by NaNO3 during the high-temperature alkaline-thermal reaction will cause environmental pollution, and it has reducing properties, it inhibits the oxidation of low-valence titanium in the slag to high-valence titanium. NaNO3 has a high risk in the high-temperature modification process, while the use of acetate, benzoate, carbonate, and bicarbonate, which produce weak oxidizing carbon dioxide, will not cause environmental pollution. At the same time, it plays a similar role to airflow stirring in the slag system, making the viscosity of the slag system smaller.

[0097] (6) The main principle of the preparation method of the calcium-titanium composite of the present invention is as follows:

[0098] ① Molten titanium-containing blast furnace slag is co-melted at high temperature with sodium and / or potassium salts, which produce CO2 oxidizing gas as a modifier. The modifier is used to reconstruct the pyroxene, which is difficult to dissolve in acid, into silicates that are easy to dissolve in acid. At the same time, the weak oxidizing gas CO2 generated by the high-temperature reaction can oxidize the low-valence state "Ti" in minerals such as diopside. Then, through thermodynamic control, the Ca and Ti in Ca and Ti-containing silicate minerals such as diopside and anorthite are reacted to achieve the enrichment of calcium titanium oxides.

[0099] ② First, acid hydrolysis with an acid solution was used to remove most of the SiO2, Al2O3, Fe2O3 and MgO from the reconstructed slag, resulting in a first-stage leaching slag. Under optimized conditions, it was found that the calcium titanium oxide content in the first-stage leaching slag obtained by direct modification with high-temperature molten slag reached 95.0165% (see Example 5). Compared with indirect modification using cold slag in the crucible, this may be because the high-temperature reaction of direct reconstruction modification with molten slag is more complete, and the magnesium chromium refractory in the furnace forms a slag skin of "reconstructed slag" after multiple tests, further reducing the impact of refractory erosion on the system.

[0100] Then, in the presence of F salt, for example under the reaction conditions of ammonium bifluoride, the small amount of insoluble silicate remaining in the above-mentioned first-stage leaching residue will be corroded by hydrofluoric acid or F ions into H2SiF6. H2SiF6 will dissolve in water and form H2O and SiF6 ions. SiF6 ions have high solubility and are not easy to reprecipitate, forming silicon fluoride, thus removing the SiO2 and other metal oxides remaining after the first-stage leaching.

[0101] Finally, a three-stage dilute acid solution is used to further remove the insoluble metal halides formed by the two-stage leaching process and the trace amounts of metal oxides and other impurities exposed after removal, thereby achieving the preparation of high-purity calcium-titanium composites. Attached Figure Description

[0102] Figure 1 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 1 are shown.

[0103] Figure 2 Here is a SEM image of the perovskite composite from Example 1;

[0104] Figure 3 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 1-1 are shown.

[0105] Figure 4 Here is a SEM image of the perovskite composite from Example 1-1;

[0106] Figure 5 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite composites in Examples 1-2 are shown.

[0107] Figure 6 SEM images of the perovskite composites of Examples 1-2;

[0108] Figure 7 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite composites in Examples 1-3 are shown.

[0109] Figure 8 SEM images of the perovskite composites in Examples 1-3;

[0110] Figure 9 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 1-4 are shown.

[0111] Figure 10 SEM images of the perovskite composites in Examples 1-4;

[0112] Figure 11 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite composites in Examples 1-5 are shown.

[0113] Figure 12 SEM images of the perovskite composites in Examples 1-5;

[0114] Figure 13 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 1-6 are shown.

[0115] Figure 14 SEM images of the perovskite composites in Examples 1-6;

[0116] Figure 15The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 2 are shown.

[0117] Figure 16 Here is a SEM image of the perovskite composite from Example 2;

[0118] Figure 17 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 2-1 are shown.

[0119] Figure 18 Here is a SEM image of the perovskite composite from Example 2-1;

[0120] Figure 19 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 2-2 are shown.

[0121] Figure 20 Here are SEM images of the perovskite composites from Example 2-2;

[0122] Figure 21 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 3 are shown.

[0123] Figure 22 Here is a SEM image of the perovskite composite from Example 3;

[0124] Figure 23 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite complex in Example 3-1 are shown.

[0125] Figure 24 Here is a SEM image of the perovskite composite from Example 3-1;

[0126] Figure 25 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 3-2 are shown.

[0127] Figure 26 SEM images of the perovskite composites in Examples 3-2;

[0128] Figure 27 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 4 are shown.

[0129] Figure 28 Here is a SEM image of the perovskite composite from Example 4;

[0130] Figure 29 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 4-1 are shown.

[0131] Figure 30 Here is a SEM image of the perovskite composite from Example 4-1;

[0132] Figure 31 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 4-2 are shown.

[0133] Figure 32 Here is a SEM image of the perovskite composite from Example 4-2;

[0134] Figure 33 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 5 are shown.

[0135] Figure 34 Here is a SEM image of the perovskite composite from Example 5;

[0136] Figure 35 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 5-1 are shown.

[0137] Figure 36 Here is a SEM image of the perovskite composite from Example 5-1;

[0138] Figure 37 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 5-2 are shown.

[0139] Figure 38 Here is a SEM image of the perovskite composite from Example 5-2;

[0140] Figure 39 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composites in Examples 5-3 are shown.

[0141] Figure 40 SEM images of the perovskite composites in Examples 5-3;

[0142] Figure 41 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite composites in Examples 5-4 are shown.

[0143] Figure 42 SEM images of the perovskite composites in Examples 5-4;

[0144] Figure 43 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composites in Examples 5-5 are shown.

[0145] Figure 44 SEM images of the perovskite composites in Examples 5-5;

[0146] Figure 45 The isotherms for BET detection of the perovskite composites in Examples 5-6;

[0147] Figure 46 SEM images of the perovskite composites in Examples 5-6;

[0148] Figure 47 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 5-7 are shown.

[0149] Figure 48 SEM images of the perovskite composites in Examples 5-7;

[0150] Figure 49 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 5-8 are shown.

[0151] Figure 50 SEM images of the perovskite composites in Examples 5-8;

[0152] Figure 51 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite composites in Examples 5-9 are shown.

[0153] Figure 52 SEM images of the perovskite composites of Examples 5-9;

[0154] Figure 53 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 5-10 are shown.

[0155] Figure 54 SEM images of the perovskite composites in Examples 5-10;

[0156] Figure 55 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 6 are shown.

[0157] Figure 56 Here is a SEM image of the perovskite composite from Example 6;

[0158] Figure 57 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 7 are shown.

[0159] Figure 58 Here is a SEM image of the perovskite composite from Example 7;

[0160] Figure 59The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 7-1 are shown.

[0161] Figure 60 Here is a SEM image of the perovskite composite from Example 7-1;

[0162] Figure 61 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 7-2 are shown.

[0163] Figure 62 SEM images of the perovskite composites of Example 7-2;

[0164] Figure 63 The isotherm (left) and BJH adsorption pore size distribution (right) of the perovskite composite BET detection in Example 8 are shown.

[0165] Figure 64 Here is a SEM image of the perovskite composite from Example 8;

[0166] Figure 65 SEM images of the perovskite complexes in Examples 10 / 10-1 / 10-2 / 10-3 / 10-4 / 10-5;

[0167] Figure 66 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 10 / 10-1 / 10-2 / 10-3 are shown.

[0168] Figure 67 The X-ray diffraction (XRD) patterns of the perovskite composites in Examples 10 / 10-1 / 10-2 / 10-3 are shown.

[0169] Figure 68 The isotherms (left) and BJH adsorption pore size distribution diagram (right) of the perovskite complexes in Examples 10 / 10-1 / 10-4 / 10-5 are shown.

[0170] Figure 69 The X-ray diffraction (XRD) spectra of the perovskite composites in Examples 10 / 10-1 / 10-4 / 10-5 are shown.

[0171] Figure 70 The image is a refined X-ray diffraction pattern of "Example 5-6 (three-stage slag)". Detailed Implementation

[0172] The present invention will be further described below with reference to specific embodiments.

[0173] A method for preparing a calcium-titanium complex, comprising the following steps:

[0174] S1. Mineral Reconstruction: Using an iron or titanium slag spoon or slag pot, molten slag is removed from the slag outlet of a metallurgical furnace and transferred to a 100kVA plasma DC electric furnace. The current and voltage are adjusted accordingly. A modifier is then added to the molten titanium-containing slag, or an oxidizing gas is introduced while adding a modifier to the molten titanium-containing slag. Mineral phase reconstruction is carried out under a constant current and at a temperature not lower than 1300℃, preferably 1300℃~1800℃, 1350℃~1500℃, 1450℃~1500℃, 1600℃~1700℃, preferably 1400℃, 1460℃, 1500℃, 1620℃, or 1700℃. After cooling, reconstructed slag is obtained, which is then crushed and / or ground to obtain reconstructed slag particles. In a specific embodiment, mineral reconstruction at 1700℃ is taken as an example.

[0175] S2. Leaching treatment: The reconstructed slag particles obtained in step S1 are subjected to leaching treatment to obtain the leachate, namely the calcium-titanium composite.

[0176] In a specific implementation, in step S1, the molten titanium-containing slag includes, but is not limited to, one or more of the following: titanium-containing blast furnace slag, ilmenite, a mixture of high-titanium slag and calcium silicate solid waste (natural mineral), ilmenite and calcium silicate solid waste (or mineral), and titanium slag (or titanium ore) and calcium silicate solid waste (or mineral). Since titanium-containing slags have similar compositions and the same reconstruction principle in mineral reconstruction, the embodiments of this application use titanium-containing blast furnace slag as an example experiment.

[0177] In a specific implementation, in step S1, the slag discharge temperature of the molten titanium-containing slag is controlled to be no less than 1300℃, preferably 1300℃~1800℃, 1350℃~1500℃, 1450℃~1500℃, 1600℃~1700℃, preferably 1400℃, 1460℃, 1500℃, or 1700℃. In this example, the slag discharge temperature of the molten titanium-containing slag is controlled to be 1350℃. The higher the slag discharge temperature, the lower the viscosity of the molten slag.

[0178] In a specific embodiment, in step S1, the modifier is one or more of the following: sodium humate, potassium sodium humate, sodium acetate, potassium acetate, sodium benzoate, potassium benzoate, sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, sodium nitrate, and potassium nitrate. Bicarbonate and carbonate have similar structures; the example uses carbonate as an example.

[0179] The above-mentioned modifier, after pretreatment, yields either blocky heavy material or granulated lightweight material, specifically:

[0180] ① The pretreatment steps for acetate are as follows: First, the acetate is heated at 120℃~180℃ to dehydrate and convert it into anhydrous acetate; the anhydrous acetate is heated to a melt (sodium acetate melting point 324℃), atomized and then rapidly cooled to form pretreated acetate particles, such as pretreated sodium acetate.

[0181] ② The pretreatment steps for benzoates are as follows: first, benzoates are dissolved in hot water, decolorized with activated carbon, and cooled to crystallize, thereby obtaining large-particle crystals and reducing intercrystalline porosity; powdered benzoates are then formed under high pressure (>50MPa) by a roller press to form pretreated benzoates, which increase the bulk density by 30% to 50%, such as pretreated potassium benzoate.

[0182] ③ The pretreatment steps for carbonates or bicarbonates are as follows:

[0183] Carbonate or bicarbonate powders are converted into blocky heavy carbonates or heavy bicarbonates through hydration crystallization, calcination, compaction, and heavyification processes, such as 20mm×20mm×20mm cubes, like heavy sodium carbonate.

[0184] or

[0185] Carbonates or bicarbonates are mixed with a binder (PVA) and then wet-granulated to obtain granulated carbonates or bicarbonates, wherein the binder (PVA) accounts for less than 1% of the weight of the carbonates or bicarbonates. In the prior art, the binder generally accounts for more than 2% of the weight. However, in this application, the binder is added to molten titanium-containing slag as a modifier, eliminating the need for a binder to ensure the strength of the granulated particles. It is only necessary to avoid dust generation during the addition of carbonates or bicarbonates, and the amount of binder can be controlled to within 1% of the weight of the carbonates or bicarbonates.

[0186] ④ The pretreatment steps for strong alkalis are as follows: molten strong alkali is formed into flakes by a roller scraper, or spherical particles are obtained by spray granulation, which is to pretreat strong alkalis, such as pretreating potassium hydroxide and sodium hydroxide.

[0187] ⑤ The pretreatment steps for nitrates are as follows: after the nitrate melt is atomized, it is rapidly cooled to form pretreated nitrate particles, such as pretreated sodium nitrate.

[0188] In a specific embodiment, in step S1, the mass of the modifier is 5% to 40%, 5% to 35%, 5% to 28%, 5% to 20%, 5% to 15%, or 5% to 10% of the mass of the titanium-containing slag. In a specific embodiment, the mass of the modifier is 28% of the mass of the titanium-containing slag.

[0189] In a specific implementation, in step S1, to further avoid dust from the modifier, the feeding pressure is negative. The hot slag can be directly fed into the plasma furnace through the slag outlet, or it can be transferred to an iron or titanium slag pot before being fed into the plasma furnace. The plasma furnace is preferably a 100kVA plasma furnace.

[0190] In a specific embodiment, the oxidizing gas in step S1 includes, but is not limited to, CO2, O2, or air. Under industrial production conditions, the oxidizing gas needs to be preheated, for example, to 300°C.

[0191] In some embodiments, step S2 involves a leaching process, the steps of which are as follows:

[0192] The reconstituted slag particles are placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid is less than or equal to 0; the purpose of the first-stage acid leaching is to remove soluble silicates from the reconstituted slag.

[0193] The acid in this section is a mixture of one or more of HCl, HF, HBr, HI, and HNO3. HI is a stronger acid than HBr and HCl. To avoid unnecessary details, HBr and HCl are used as examples in the specific implementation.

[0194] The mass ratio of the reconstituted residue particles to the volume of the first-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, 0-60℃, 0-50℃, 0-40℃, 10-40℃, 20-35℃, 20℃, 25℃, 30℃, 35℃ or 80℃; the leaching reaction time is 0.5-2 h.

[0195] When the leaching system temperature is 0℃, i.e. in an ice-water bath environment, the ratio of the mass of the reconstituted slag particles to the volume of the first stage acid is 1g:(5~10ml), which can increase the solid-liquid ratio and reduce the acid consumption for titanium enrichment in existing technologies.

[0196] In some embodiments, in order to further strip away the unreconstructed insoluble silicates, step S2 involves a two-stage leaching process to obtain the leachate, namely the calcium-titanium complex, which includes at least one leaching process containing F salt or F acid.

[0197] Specifically:

[0198] S21, First-stage acid leaching: The reconstituted slag particles are placed in a first-stage acid solution, and after filtration, washing, and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid solution is less than or equal to 0; the purpose of the first-stage acid leaching is to remove soluble silicates from the reconstituted slag.

[0199] The first-stage acid is a mixture of one or more of HCl, HF, HBr, HI, and HNO3. The mass ratio of the reconstructed residue particles to the volume of the first-stage acid is 1 g:(5-25 ml). The leaching system temperature is 0-80℃, 0-60℃, 0-50℃, 0-40℃, 10-40℃, 20-35℃, 20℃, 25℃, 30℃, 35℃, or 80℃. The leaching reaction time is 0.5-2 h.

[0200] When the leaching system temperature is 0℃, i.e. in an ice-water bath environment, the ratio of the mass of the reconstituted slag particles to the volume of the first stage acid is 1g:(5~10ml), which can increase the solid-liquid ratio and reduce the acid consumption for titanium enrichment in existing technologies.

[0201] S22. Two-stage leaching: The first-stage leachate is placed in a leachate containing F salt or F acid, and after filtration, washing, and drying, a second-stage leachate is obtained; wherein the effective components of the leachate include, but are not limited to, HF and NH4HF2 solution.

[0202] The mass concentration of the effective components in the leachate is 0.5% to 10%. For example, when the leachate is an NH4HF2 solution, the mass concentration of the NH4HF2 solution is 0.5% to 10%, and the mass ratio of a portion of the leachate to the volume of the NH4HF2 solution is 1 g:(5 to 25 ml). The leaching system temperature is 0 to 80°C, 0 to 60°C, 0 to 50°C, 0 to 40°C, 10 to 40°C, 20 to 35°C, 20°C, 25°C, 30°C, 35°C, or 80°C, and the leaching reaction time is 0.5 to 2 hours.

[0203] In some embodiments, step S2 includes three leaching processes, namely:

[0204] S21, First-stage acid leaching: The reconstituted slag particles are placed in a first-stage acid solution, and after filtration, washing, and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid solution is less than or equal to 0; the purpose of the first-stage acid leaching is to remove soluble silicates from the reconstituted slag.

[0205] The first-stage acid is a mixture of one or more of HCl, HF, HBr, HI, and HNO3. The mass ratio of the reconstructed residue particles to the volume of the first-stage acid is 1 g:(5-25 ml). The leaching system temperature is 0-80℃, 0-60℃, 0-50℃, 0-40℃, 10-40℃, 20-35℃, 20℃, 25℃, 30℃, 35℃, or 80℃, and the leaching reaction time is 0.5-2 h.

[0206] When the leaching system temperature is 0℃, i.e. in an ice-water bath environment, the ratio of the mass of the reconstituted slag particles to the volume of the first stage acid is 1g:(5~10ml), which can increase the solid-liquid ratio and reduce the acid consumption for titanium enrichment in existing technologies.

[0207] S22. Two-stage leaching: The first-stage leachate is placed in a leachate containing F salt or F acid, and after filtration, washing, and drying, a second-stage leachate is obtained; wherein the effective components of the leachate include, but are not limited to, HF and NH4HF2 solution.

[0208] The mass concentration of the effective components in the leachate is 0.5% to 10%. For example, when the leachate is an NH4HF2 solution, the mass concentration of the NH4HF2 solution is 0.5% to 10%, and the mass ratio of a portion of the leachate to the volume of the NH4HF2 solution is 1 g:(5 to 25 ml). The leaching system temperature is 0 to 80°C, 0 to 60°C, 0 to 50°C, 0 to 40°C, 10 to 40°C, 20 to 35°C, 20°C, 25°C, 30°C, 35°C, or 80°C, and the leaching reaction time is 0.5 to 2 hours.

[0209] S23. Three-stage leaching: The two-stage leachate is placed in a three-stage acid, and after filtration, washing, and drying, a three-stage leachate, i.e., a calcium-titanium complex, is obtained; wherein, the pH value of the three-stage acid is greater than 0, preferably 0.5 or 1.0.

[0210] The three-stage acid is one or a mixture of HCl, HF, HBr, HI, and HNO3. The mass ratio of the two-stage extract to the volume of the three-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, 0-60℃, 0-50℃, 0-40℃, 10-40℃, 20-35℃, 20℃, 25℃, 30℃, 35℃, or 80℃, and the leaching reaction time is 0.5-2 h.

[0211] The yields of the first-stage slag, second-stage slag, and third-stage slag must be at least 25%. It should be noted that the yield of the first-stage slag = mass of the first-stage slag / mass of the reconstituted slag; the yield of the second-stage slag = mass of the second-stage slag / mass of the reconstituted slag; and the yield of the third-stage slag = mass of the third-stage slag / mass of the reconstituted slag.

[0212] (I) Mineral Reconstruction

[0213] In a specific implementation, the parameters for mineral reconstruction are shown in Table 1:

[0214] Table 1. Parameters for mineral reconstruction in step S1 of each embodiment.

[0215]

[0216] (II) Leaching Treatment

[0217] Example 1

[0218] Example 1 is the product after a single leaching step, labeled "Example 1 (Single Step Residue)", and its single leaching conditions are as follows:

[0219] Using "Example 1 (first stage leaching)" as a sample, two-stage or three-stage leaching was continued to obtain Examples 1-1 to Examples 1-6:

[0220]

[0221] Example 2

[0222] Example 2 uses HBr as the first-stage leachate to prepare two sets of first-stage residues. The first-stage leaching conditions are as follows:

[0223]

[0224] Using the first stage leaching obtained in Example 2-1 as a sample, second-stage and third-stage leaching were continued to obtain "Example 2-1 (Second-stage leaching)" and "Example 2-2 (Third-stage leaching)":

[0225]

[0226] Example 3

[0227] Example 3 is the product after a single leaching step, labeled "Example 3 (Single Step Residue)", and its single leaching conditions are as follows:

[0228]

[0229] Using "Example 3 (first stage leaching)" as a sample, two-stage or three-stage leaching was continued to obtain Examples 3-1 to 3-2:

[0230]

[0231] Example 4

[0232] Example 4 is the product after a single leaching step, labeled "Example 4 (Single Step Residue)", and its single leaching conditions are as follows:

[0233]

[0234] Using "Example 4 (first stage leaching)" as a sample, two-stage or three-stage leaching was continued to obtain Examples 4-1 to 4-2:

[0235]

[0236] Example 5

[0237] Example 5 is the product after a single leaching step, labeled "Example 5 (Single Step Residue)", and its single leaching conditions are as follows:

[0238]

[0239] Using "Example 5 (first stage leaching)" as a sample, two-stage or three-stage leaching was continued to obtain Examples 5-1 to 5-10:

[0240]

[0241] Example 6

[0242] Example 6 is the product after a single leaching step, labeled "Example 6 (Single Step Residue)", and its single leaching conditions are as follows:

[0243]

[0244] Example 7

[0245] Example 7 is the product after a single leaching step, labeled "Example 7 (Single Step Residue)", and its single leaching conditions are as follows:

[0246]

[0247] Using "Example 7 (first stage leaching)" as a sample, two-stage or three-stage leaching was continued to obtain Examples 7-1 to 7-2:

[0248]

[0249] Example 8

[0250] Example 8 is the product after a single leaching step, labeled "Example 8 (Single Step Residue)", and its single leaching conditions are as follows:

[0251]

[0252] Example 9

[0253] Example 9 uses HNO3 as the first-stage leachate to prepare two sets of first-stage residues. The first-stage leaching conditions are as follows:

[0254]

[0255] Example 10

[0256] Example 10 is the reconstructed residue obtained by reconstructing with pretreated K2CO3 as a modifier, denoted as "S0 (Example 10)".

[0257] In this embodiment, the reconstructed slag is denoted as S0, the first-stage slag as S1, the second-stage slag as S2, and the third-stage slag as S3.

[0258] Example 10-1

[0259] Using S0 (Example 10) as a sample, the product after a further leaching is labeled "S1 (Example 10-1)", and the leaching conditions for this first leaching are as follows:

[0260]

[0261] Examples 10-2 to 10-5

[0262] Using "S1 (Example 10-1)" as a sample, two-stage or three-stage leaching was continued, namely Examples 10-2 to Examples 10-5, resulting in S2 and S3 respectively:

[0263]

[0264] Performance testing

[0265] The samples obtained in the above embodiments were subjected to BET, XRF, and SEM tests, and the results are as follows:

[0266] BET Analysis

[0267] Table 2. BET detection results of samples in Examples 1-8 and 10.

[0268]

[0269]

[0270] Based on Table 2 Figure 1 , 3 The N2 adsorption-desorption isotherms and pore size distributions shown in figures 5, 7, 9, 11, 13, 15, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 37, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 66, and 68 show that the specific surface area of ​​each embodiment ranges from 0.45 to 28.79 m². 2 / g, total pore volume distribution ranges from 0.0005 to 0.0427 cm³. 3 / g, pore size distribution ranges from 5.06 to 22.93 nm; among which:

[0271] The slag section has a specific surface area ranging from 9.41 to 28.79 m². 2 / g, total pore volume distribution ranges from 0.026 to 0.043 cm³. 3 / g, with a pore size distribution of 5.09–11.26 nm;

[0272] The secondary slag has a specific surface area distribution of 6.63–14.33 m². 2 / g, total pore volume distribution ranges from 0.023 to 0.043 cm³. 3 / g, with a pore size distribution of 11.91–18.78 nm;

[0273] The three slag sections have a specific surface area distribution ranging from 0.45 to 10.04 m². 2 / g, total pore volume distribution ranges from 0.0005 to 0.0377 cm³. 3 / g, with a pore size distribution of 5.06–22.93 nm.

[0274] In the experiments of Example 1, as can be seen from Examples 1, 1-1, and 1-2, adding two-stage leaching with NH4HF2 and three-stage leaching with dilute hydrochloric acid resulted in a gradual decrease in the specific surface area and a gradual increase in the pore size of the leaching residue sample. This indicates that after leaching with NH4HF2 in the first stage, silicates inside the pores can be further removed, but a small amount of insoluble fluoride salts will be generated and adhere to the surface of the perovskite oxide. Further leaching in the third stage with dilute acid, where strong acid replaces weak acid salts, achieves efficient removal of insoluble fluoride salts. Comparisons of other examples also conform to the above pattern.

[0275] As can be seen from S0 (Example 10), S1 (Example 10-1), S2 (Example 10-2), S3 (Example 10-3) or S0 (Example 10), S1 (Example 10-1), S2 (Example 10-4), S3 (Example 10-5), after the reconstructed residue undergoes a first stage of concentrated hydrochloric acid leaching, a second stage of NH4HF2 leaching, and a third stage of dilute hydrochloric acid leaching, the specific surface area decreases and the pore size increases.

[0276] XRF analysis

[0277] Table 3 Chemical composition analysis of each embodiment (wt%, the sum of the components of each embodiment is 100%, some components are not recorded)

[0278]

[0279]

[0280]

[0281] In Table 3:

[0282] (1) In mineral reconstruction, the type of modifier affects the reconstruction effect: acetate > benzoate > carbonate.

[0283] Examples 1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9-1 / 9-2 are all single-stage slag, wherein:

[0284] ① Direct modification of molten titanium-containing slag: After a leaching process, the content of calcium titanium compounds (CaO+TiO2) reaches 95.0165%. For example, in Examples 5 / 6 / 7 / 8, even after only one acid leaching process, the content of calcium titanium compounds (CaO+TiO2) reaches 94-95%, which is much higher than the 87% disclosed by the inventors in their 2012 application (application number 201210004204.3). This fully demonstrates that the process of directly modifying molten titanium-containing slag in a furnace using high-temperature molten titanium-containing slag has made significant progress.

[0285] ② In Examples 1-3, nitrates and strong alkalis were used as modifiers. Although CO2 was introduced, the content of perovskite compounds (CaO+TiO2) was less than 90%. However, in Examples 1-5 / 1-6, it was seen that the content of perovskite compounds in the first stage of slag from Example 1 could be significantly increased to about 95% after two stages of NH4HF2 leaching and three stages of HCl leaching. Moreover, after two stages of 5% NH4HF2 leaching and three stages of HCl leaching, the pore size was significantly increased to 22.93 nm.

[0286] ③ In Example 4, sodium carbonate was used as a modifier, and the content of calcium titanium compounds (CaO+TiO2) was increased compared with Examples 1-3;

[0287] ④ Examples 5-8 use acetate or benzoate as modifiers, and the content of perovskite compound (CaO+TiO2) reaches about 95%. However, in Examples 5-1 / 5-2 / 5-9 / 5-10, the higher concentration of ammonium bifluoride (≥5%) can dissolve calcium in the perovskite compound. However, at low temperature (20°C), the solubility of sparingly soluble fluoride salts combining calcium and fluorine is low, making it difficult to enter the leachate. Therefore, the content of perovskite compound (CaO+TiO2) in Examples 5-1 / 5-2 / 5-9 / 5-10 is low.

[0288] ⑤ Examples 9-1 / 9-2 use nitric acid for a single leaching process. In Example 9-1, the content of calcium titanium compounds (CaO+TiO2) is higher after leaching for 0.5 hours. In Example 9-2, leaching for 1 hour may cause the dissolved silica to re-gel, resulting in a higher SiO2 content.

[0289] ⑥ Examples 10 / 10-1 / 10-2 / 10-3 / 10-4 / 10-5 show that after leaching with concentrated hydrochloric acid, the content of calcium titanium oxides (CaO+TiO2) increases. After further leaching with NH4HF2 in the second stage, the content of calcium titanium oxides (CaO+TiO2) decreases. However, after further leaching with dilute hydrochloric acid, the content of calcium titanium oxides (CaO+TiO2) in S3 is further increased compared with S1. This indicates that NH4HF2 removes the unreconstructed insoluble silicates covering the surface of soluble silicates, and then leaching with dilute hydrochloric acid increases the content of calcium titanium oxides (CaO+TiO2).

[0290] (2) After the first stage slag was leached in the second and third stages, the content of calcium and titanium compounds (CaO+TiO2) was significantly increased.

[0291] For example, a comparison of Examples 1, 1-1, and 1-2 shows that the calcium titanium oxide content (CaO + TiO2) of the three-stage slag is significantly higher than that of the single-stage slag under the same conditions. The reason for this is as follows:

[0292] Acid leaching removes most of the soluble silicates, creating pores and exposing more magnesium and aluminum oxides.

[0293] After the second stage of leaching, a small amount of unreconstructed insoluble silicates are further stripped off. At the same time, the surface is further exposed to magnesium and aluminum oxides, which react with ammonium bifluoride to form corresponding fluoride salts. The easily soluble fluoride salts are stripped off and dissolved in the leaching solution, which further expands the pores of the sample. The insoluble fluorides form a loose structure, such as magnesium fluoride and aluminum fluoride.

[0294] In the three-stage acid leaching process, the sparingly soluble fluoride is further dissolved in the leachate by a displacement reaction to form a weak acid salt (a strong acid displaces a weak acid salt).

[0295] SEM analysis

[0296] Figure 2 , 4 Images 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, and 65 are SEM surface morphology images of the calcium-titanium composites in each embodiment. It can be seen that after acid leaching, the sample surface becomes porous and loose, and the sample size decreases, gradually transforming from unevenly sized blocky particles into clustered particles.

[0297] XRD analysis

[0298] (1) The X-ray diffraction (XRD) spectra of the perovskite composites in Examples 10 / 10-1 / 10-2 / 10-3 and Examples 10 / 10-1 / 10-4 / 10-5 are as follows: Figure 67 , 69 As shown, the three-stage slag obtained after three-stage wet leaching is mainly composed of CaO and TiO2, and the mineral phases detected are basically all calcium titanium oxide phases, and the grade of calcium titanium oxide can even reach 97.97% (Examples 5-6 (three-stage slag)).

[0299] (2) In Examples 5-6, the content of calcium titanium compounds (CaO+TiO2) in “Example 5-6 (three-stage slag)” reached 97.97%. Since “Example 5-6 (three-stage slag)” was specifically used as a sample, XRD refinement analysis was performed, as shown in Table 4:

[0300] Table 4. XRD refinement images of each mineral phase from Examples 5-6 (three-stage slag) (combined with...) Figure 70 )

[0301]

[0302] As shown in Table 4, the CaTiO3 phase in "Examples 5-6 (Three-stage slag)" reached 99.52%. Combined with the BET test results of Examples 5-6 (Three-stage slag) in Table 2, it can be seen that almost all the sparingly soluble components in Examples 5-6 were dissolved, leading to the collapse of the network structure and a decrease in pore size and volume.

[0303] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the art; the methods used in this invention, unless otherwise specified, are all conventional methods in the art. The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the invention. Any simple modifications, alterations, and equivalent transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A perovskite composite, characterized in that: Including perovskite oxides, which have porous structures both on the surface and inside, wherein: Specific surface area is 0–30 m² 2 / g, preferably 10-30m 2 / g, preferably 10-15m 2 / g, preferably 0.45~10m 2 / g; The pore volume is greater than 0.0005 cm³. 3 / g, preferably 0.0005~0.05cm 3 / g, preferably 0.0005~0.04cm 3 / g, preferably 0.02~0.04cm 3 / g; The pore size of the pore structure is greater than 5 nm, preferably 5–12 nm, more preferably 11–19 nm, and more preferably 18–25 nm.

2. The calcium-titanium composite according to claim 1, characterized in that: Specific surface area distribution is 9–29 m² 2 / g, total pore volume distribution is 0.02–0.05 cm³. 3 / g, with a pore size distribution of 5–12 nm.

3. The calcium-titanium composite according to claim 1, characterized in that: Specific surface area distribution is 6–15 m² 2 / g, total pore volume distribution is 0.02–0.05 cm³. 3 / g, with a pore size distribution of 11–20 nm.

4. The calcium-titanium composite according to claim 1, characterized in that: Specific surface area ranges from 0.45 to 10 m². 2 / g, total pore volume distribution is 0.0005–0.04 cm³. 3 / g, with a pore size distribution of 5–25 nm.

5. A calcium-titanium composite according to any one of claims 1 to 4, characterized in that: The calcium titanium composite contains more than 30% calcium titanium oxide, preferably more than 50%, more than 70%, more than 80%, more than 90%, more than 95%, more than 98%, and more than 99.52%.

6. A calcium-titanium composite according to claim 5, characterized in that: The titanium oxide content in the calcium-titanium composite is greater than 40%, preferably 40-60%.

7. A method for preparing a perovskite composite, characterized in that: S1. Mineral Reconstruction: A modifier is added to the molten titanium-containing slag, or a modifier is added to the molten titanium-containing slag while an oxidizing gas is introduced, and mineral phase reconstruction is carried out at a temperature not lower than 1300℃, preferably 1300℃~1800℃, 1350℃~1500℃, 1450℃~1500℃, 1600℃~1700℃, preferably 1400℃, 1460℃, 1500℃, 1620℃, 1700℃. After cooling, the reconstructed slag is obtained, and then crushed and / or ground to obtain reconstructed slag particles. S2. Leaching treatment: The reconstructed slag particles obtained in step S1 are subjected to leaching treatment to obtain the leachate, namely the calcium-titanium composite.

8. The preparation method according to claim 7, characterized in that: In step S1, the oxidizing gas includes, but is not limited to, CO2, O2, or air.

9. The preparation method according to claim 7, characterized in that: In step S1, the mass of the modifier is 5% to 40% of the mass of the titanium-containing slag, preferably 15% to 40% of the mass of the titanium-containing slag, preferably 15% to 35% of the mass of the titanium-containing slag, preferably 15% to 28% of the mass of the titanium-containing slag, preferably 28% to 35% of the mass of the titanium-containing slag, preferably 28% to 40% of the mass of the titanium-containing slag, and preferably 35% to 40% of the mass of the titanium-containing slag.

10. The preparation method according to claim 7, characterized in that: In step S1, the titanium-containing slag includes, but is not limited to, one or more of the following: titanium-containing blast furnace slag, ilmenite, a mixture of high-titanium slag and calcium-containing silicate minerals, a mixture of ilmenite and calcium-containing silicate minerals, and a mixture of titanium slag and calcium-containing silicate minerals.

11. The preparation method according to claim 7, characterized in that: In step S1, the modifier is a sodium- or potassium-containing compound, preferably a sodium- or potassium-containing compound that easily generates oxidizing gases, including but not limited to organic compounds and inorganic compounds. The effective components of the organic compound are one or more of sodium acetate, potassium acetate, sodium benzoate, potassium benzoate, etc.; the effective components of the inorganic compound are one or more of sodium carbonate, sodium bicarbonate, potassium carbonate, potassium bicarbonate, sodium hydroxide, potassium hydroxide, sodium nitrate, potassium nitrate, etc.

12. The preparation method according to claim 7, characterized in that: In step S1, the modifier is a blocky heavy material or a granulated lightweight material.

13. The preparation method according to claim 7, characterized in that: In step S1, the feed pressure of the modifier is negative.

14. The preparation method according to claim 7, characterized in that: In step S1, the mineral phase reconstruction is carried out at a temperature of not less than 1300℃ for the molten titanium-containing slag, preferably 1300℃~1800℃, 1350℃~1500℃, 1450℃~1500℃, 1600℃~1700℃, and more preferably 1350℃, 1400℃, 1460℃, 1500℃, 1620℃, and 1700℃.

15. The preparation method according to claim 7, characterized in that: In step S2, a first- to third-stage leaching process is used to obtain a calcium-titanium composite, wherein the calcium-titanium oxide content in the calcium-titanium composite is greater than 80%.

16. The preparation method according to claim 15, characterized in that: In step S2, a single-stage leaching process is employed, and the steps are as follows: The reconstituted slag particles were placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate was obtained; wherein the pH value of the first-stage acid was less than or equal to 0.

17. The preparation method according to claim 15, characterized in that: Step S2 includes two leaching processes: S21, First-stage acid leaching: The reconstituted residue particles are placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid is less than or equal to 0; S22, Two-stage leaching: The first-stage leachate is placed in a leachate containing F salt or F acid, and after filtration, washing and drying, a second-stage leachate is obtained; wherein, the effective components of the leachate include, but are not limited to, HF and NH4HF2 solution.

18. The preparation method according to claim 15, characterized in that: Step S2 includes three leaching processes, namely: S21, First-stage acid leaching: The reconstituted residue particles are placed in a first-stage acid, and after filtration, washing and drying, a first-stage leachate is obtained; wherein, the pH value of the first-stage acid is less than or equal to 0; S22, Two-stage leaching: The first-stage leachate is placed in a leachate containing F salt or F acid, and after filtration, washing and drying, a second-stage leachate is obtained; wherein, the effective components of the leachate include, but are not limited to, HF and NH4HF2 solution. S23, Three-stage acid leaching: The two-stage extract is placed in a three-stage acid, and after filtration, washing and drying, a three-stage extract, namely a calcium-titanium complex, is obtained; wherein, the pH value of the three-stage acid is greater than 0, preferably the pH value of the three-stage acid is 0.5 or 1.

0.

19. The preparation method according to any one of claims 16 to 18, characterized in that: The first-stage acid is one or a mixture of HCl, HF, HBr, HI, and HNO3. The mass ratio of the reconstituted residue particles to the volume of the first-stage acid is 1 g:(5-25 ml). The leaching system temperature is 0-80℃, preferably 0-60℃, preferably 0-50℃, preferably 0-40℃, preferably 10-40℃, preferably 20-35℃, preferably 20℃, 25℃, 30℃, 35℃, and 80℃. The leaching reaction time is 0.5-2 h.

20. The preparation method according to claim 19, characterized in that: When the leaching system temperature is below or equal to 0℃, the ratio of the mass of the reconstituted residue particles to the volume of the first stage acid is 1g:(5~10ml).

21. The preparation method according to any one of claims 17-18, characterized in that: In step S22, the mass concentration of the effective component in the leachate is 0.5% to 10%. For example, when the leachate is an NH4HF2 solution, the mass concentration of the NH4HF2 solution is 0.5% to 10%, and the mass ratio of a portion of the leachate to the volume of the NH4HF2 solution is 1 g:(5 to 25 ml). The leaching system temperature is 0 to 80°C, preferably 0 to 60°C, preferably 0 to 50°C, preferably 0 to 40°C, preferably 10 to 40°C, preferably 20 to 35°C, preferably 20°C, 25°C, 30°C, 35°C, or 80°C, and the leaching reaction time is 0.5 to 2 hours.

22. The preparation method according to claim 18, characterized in that: In step S23, the three-stage acid is one or a mixture of HCl, HF, HBr, HI, and HNO3; the mass ratio of the two-stage extract to the volume of the three-stage acid is 1 g:(5-25 ml); the leaching system temperature is 0-80℃, preferably 0-60℃, preferably 0-50℃, preferably 0-40℃, preferably 10-40℃, preferably 20-35℃, preferably 20℃, 25℃, 30℃, 35℃, and 80℃, and the leaching reaction time is 0.5-2 h.

23. The application of the calcium-titanium composite according to any one of claims 1 to 5 in the production and preparation of titanium-containing products such as titanium alloys, sponge titanium, titanium tetrachloride, ceramic materials, welding materials, electronic materials, semiconductor materials, dielectric materials, catalysts, catalyst supports, coating materials, thermoelectric materials, and microwave absorbing materials.

24. The application according to claim 23, characterized in that: The catalysts include, but are not limited to, coal-fired sulfur and nitrogen fixation additives and combustion catalysts.

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