Method for preparing titanium tetrachloride from titanium-containing composite slag through low-temperature selective chlorination

Abstract

The invention relates to the technical field of titanium metallurgy, and discloses a method for preparing titanium tetrachloride from titanium-containing composite slag through low-temperature selective chlorination, which comprises the following steps: providing the titanium-containing composite slag which comprises a multiphase solid material of a TiCxOy phase and a melilite phase; the method comprises the following steps: putting titanium-containing composite slag into a reactor, and heating to 350-700 DEG C; introducing chlorine-containing gas into the reactor, and contacting the chlorine-containing gas with the titanium-containing composite slag to carry out selective chlorination reaction; and collecting and condensing gas generated in the reaction process to obtain a TiCl4 product, and discharging chlorination residues after the reaction. The method provided by the invention overcomes the dilemma in the traditional process, efficiently extracts titanium through a low-temperature selective chlorination technology, inhibits chlorination of impurities such as calcium and magnesium from the source, and realizes green production.

Description

Technical Field

[0001] This invention relates to the field of titanium metallurgy, and in particular to a method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination. Background Technology

[0002] Titanium and its compounds are important strategic materials, widely used in aerospace, marine engineering, and high-end chemical industries. Titanium tetrachloride, as a key intermediate raw material for the production of sponge titanium and chloride-process titanium dioxide, requires efficient and green preparation technologies that are crucial for the independent development of my country's titanium industry.

[0003] Currently, the main industrial processes for large-scale TiCl4 production are the fluidized bed chlorination and molten salt chlorination. However, both of these mainstream processes have stringent requirements for raw material quality, necessitating the use of titanium-rich materials (such as synthetic rutile and high-grade titanium slag) with a TiO2 content higher than 90% and a calcium and magnesium impurity content lower than 1.5%. The vanadium-titanium magnetite deposits abundant in regions like Panzhihua and Xichang produce titanium-containing slag from their smelting, which is a typical low-grade, high-calcium-magnesium-titanium resource and cannot be directly used in the aforementioned mature processes. Existing technologies face a dilemma regarding "efficiency-environmental protection" and "cost-recovery rate" when processing low-grade, high-calcium-magnesium-titanium resources: pursuing reaction efficiency leads to furnace slag formation and hazardous waste problems; adding pretreatment and separation steps to avoid hazardous waste results in complex processes, increased costs, and incomplete resource recovery.

[0004] Therefore, there is a need in the existing technology for a new, green, and efficient method for titanium extraction that is simple in process and can inhibit calcium and magnesium chlorination at the source. Summary of the Invention

[0005] In view of this, the purpose of this invention is to propose a method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination, which overcomes the difficulties in traditional processes. By using low-temperature selective chlorination technology, titanium can be extracted efficiently while inhibiting the chlorination of impurities such as calcium and magnesium from the source, thus achieving green production.

[0006] To achieve the above objectives, embodiments of the present invention provide a method for the low-temperature selective chlorination of titanium-containing composite slag to produce titanium tetrachloride, comprising: S1 provides titanium-containing composite slag, including TiC. x O y Multiphase solid materials containing both diatomite and feldspar phases; S2 places the titanium-containing composite slag in a reactor and heats it to 350℃~700℃; S3 introduces chlorine-containing gas into the reactor, which then contacts the titanium-containing composite slag to carry out a selective chlorination reaction. S4 collects and condenses the gas produced during the reaction to obtain TiCl4 product, and discharges the chlorination residue after the reaction.

[0007] In some embodiments, in S1, the titanium-containing composite slag also includes a metallic iron phase.

[0008] In some embodiments, in S2, the titanium-containing composite slag is heated to 350°C to 650°C.

[0009] In some embodiments, the selective chlorination reaction in S3 takes 15 minutes to 3 hours.

[0010] In some embodiments, in S3, the chlorine-containing gas is chlorine or a mixture of chlorine and an inert gas, wherein the volume concentration of chlorine is not less than 50%.

[0011] In some implementations, the chlorine-containing gas comes from liquid chlorine evaporation gas or factory circulating chlorine gas.

[0012] In some embodiments, in S1, the titanium-containing composite slag is obtained by carbonization-reduction smelting of titanium slag containing perovskite.

[0013] In some embodiments, the feldspar phase is at least one of aluminum feldspar or magnesium feldspar.

[0014] In some embodiments, in S3, the reaction conditions are controlled such that the area fraction of the feldspar phase in the residue after the reaction remains at more than 60% of that before the reaction.

[0015] In some implementations, the reactor is a fixed-bed reactor or a fluidized-bed reactor.

[0016] The present invention has at least the following beneficial technical effects: (1) By carrying out the reaction in a specific low temperature range, using TiC x O y The significant difference in chlorination reactivity between TiC and the feldspar matrix enabled the realization of TiC. x O y The preferential selective chlorination shortens the process flow and reduces equipment investment and operating costs. The feldspar matrix remains stable after the reaction, which significantly reduces the generation of hazardous wastes such as CaCl2 and MgCl2 from the source, alleviating environmental pressure and subsequent treatment burden.

[0017] (2) The core chlorination reaction temperature is significantly lower than that of the traditional smelting chlorination process (>750℃), and there is no need to continuously supply heat to maintain the molten pool, which effectively reduces the system energy consumption and improves the economic efficiency of the process.

[0018] (3) The method of the present invention has more relaxed requirements on the physical form and purity of the raw materials, and is particularly suitable for processing low-grade, high-calcium-magnesium complex titanium resources that are tightly embedded with the titanium phase and gangue minerals and are difficult to be efficiently enriched by physical methods. This broadens the range of usable titanium raw materials and improves the ability to guarantee strategic resources.

[0019] (4) The chlorinated residue is mainly composed of a relatively stable feldspar structure. Its hygroscopicity and corrosivity are much lower than those of waste salt rich in CaCl2 / MgCl2, which provides a better foundation for subsequent safe storage or recycling of valuable elements. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of an embodiment of the method for producing titanium tetrachloride from titanium-containing composite slag at low temperature selective chlorination according to the present invention. Figure 2 The flowchart for the chlorination preparation of titanium tetrachloride provided by this invention; Figure 3 The TiC-containing material provided by this invention x O y Microstructure and phase distribution of slag particles before reaction Figure 4 The microstructure and phase distribution diagram of the post-reaction chlorination residue particles provided by this invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0023] The terms "comprising" and "having," and any variations thereof, used in the specification, claims, and accompanying drawings of this invention are intended to cover non-exclusive inclusion; the terms "first," "second," etc., used in the specification, claims, and accompanying drawings are used to distinguish different objects, not to describe a particular order. "A plurality of" means two or more, unless otherwise explicitly specified.

[0024] Furthermore, the reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0025] To address the problems in existing technologies, there is an urgent need to develop technologies that can implement TiC-containing... x O y Selective separation and extraction of TiCl4 from slag promotes the production of TiCl4 from low-grade titanium raw materials in my country, further enabling the production of high-quality chloride-process titanium dioxide and sponge titanium, while avoiding the generation of large amounts of hazardous waste such as CaCl2 and MgCl2. Those skilled in the art will understand the benefits of TiCl4-containing titanium dioxide. x O y There is insufficient research on the phase transformation mechanism during the separation and extraction of TiCl4 from TiC residues, resulting in a lack of methods for efficient and selective separation and extraction of TiCl4. There is an urgent need to develop a green and efficient method for extracting TiCl4 from TiC-containing residues. x O y Methods for producing TiCl4 from titanium-containing composite slag. Therefore, this invention proposes a method for the low-temperature selective chlorination of titanium tetrachloride from titanium-containing composite slag, such as... Figure 1 and Figure 2 As shown, the method of the present invention includes: S1 provides titanium-containing composite slag, including TiC. x O y Multiphase solid materials containing both diatomite and feldspar phases; S2 places the titanium-containing composite slag in a reactor and heats it to 350℃~700℃; S3 introduces chlorine-containing gas into the reactor, which then contacts the titanium-containing composite slag to carry out a selective chlorination reaction. S4 collects and condenses the gas produced during the reaction to obtain TiCl4 product, and discharges the chlorination residue after the reaction.

[0026] Furthermore, in S1, the titanium-containing composite slag is obtained by carbonization-reduction smelting of perovskite-containing titanium slag, and the titanium-containing composite slag may also include a metallic iron phase. Preferably, the feldspar phase is at least one of aluminum feldspar or magnesium feldspar.

[0027] Furthermore, in S2, preferably, the titanium-containing composite slag is heated to 350℃~650℃, and the temperature can be constant or variable.

[0028] Further, in S3, the chlorine-containing gas is chlorine gas or a mixture of chlorine gas and an inert gas, wherein the volume concentration of chlorine gas is not less than 50%. The chlorine-containing gas comes from liquid chlorine evaporation gas or factory circulating chlorine gas. The selective chlorination reaction takes 15 minutes to 3 hours, and the reaction conditions are controlled so that the area fraction of the feldspar phase in the residue after the reaction remains at more than 60% of that before the reaction. In some embodiments, the reactor is a fixed-bed reactor or a fluidized-bed reactor.

[0029] The TiC-containing [material] of this invention x O yMethod for preparing TiCl4 from slag, where 0 < x ≤ 1 and y = 1 - x. This method uses TiC-containing x O y slag to react with chlorine gas to produce TiCl4. After the reaction, the area fraction of TiC inside the particles x O y significantly decreases, while the area fraction of the main particle melilite changes insignificantly, indicating that TiC x O y undergoes preferential selective chlorination, achieving efficient titanium extraction and providing a basis for the subsequent green resource utilization of chlorination residues.

[0030] The present invention provides a simplified method for low-temperature titanium extraction by directly chlorinating "TiC x O y , melilite, metallic iron multiphase composite slag" with a specific microstructure without prior sorting and iron removal, eliminating or reducing the pretreatment requirements for deep physical sorting of raw materials. At a relatively low temperature (350 - 650 °C), chlorine gas can selectively react with TiC x O y dispersed in the chemically inert melilite matrix, while the matrix itself remains stable. This is an "in-situ selective chlorination" mechanism based on the difference in phase reaction activity and microscale mass transfer. It realizes the efficient extraction of titanium from low-grade, high-calcium, magnesium, and titanium resources, while maximizing the inhibition of calcium and magnesium chlorination, reducing the generation of hazardous wastes such as CaCl2 and MgCl2 from the source, making the chlorination residues easier for subsequent environmental protection treatment or resource utilization, and having significant green environmental protection benefits.

[0031] The following further explains and illustrates the present invention with specific examples.

[0032] Example 1 Weigh 100.0 grams of the above-mentioned TiC-containing x O y composite slag, evenly spread it on a quartz reaction boat, and push it into the heating zone of the reactor. Introduce high-purity nitrogen gas into the reactor as a protective gas and purge gas, then raise the temperature of the reaction zone to 350 °C and keep it constant at this temperature for 15 minutes to ensure uniform material temperature.

[0033] Maintain the temperature at 350 °C ± 5 °C. Switch the gas to pure chlorine gas and control the chlorine gas flow rate at 50 mL / min. Carry out the chlorination reaction under these conditions, and the total reaction duration is 2.5 hours. During the reaction process, it can be observed that white smoky gas is generated and enters the water-cooled sleeve condenser.

[0034] After the reaction is complete, the inlet gas is first switched back to nitrogen to purge the pipeline and reactor for 10 minutes to remove residual chlorine and product gases. The liquid product in the condenser is collected; this liquid is a crude TiCl4 product ranging from wine red to colorless.

[0035] Under nitrogen protection, the reaction boat was cooled to room temperature, the solid residue after the reaction was removed, weighed, and characterized.

[0036] Results: The yield of crude TiCl4 was 21.5 g, which is approximately 52.4% based on the theoretical yield of all titanium in the raw material being converted into TiCl4. X-ray diffraction (XRD) analysis of the chlorination residue showed that the diffraction peaks of the feldspar phase were still obvious, and no obvious CaCl2 or MgCl2 crystalline phases were detected.

[0037] Example 2 The operation is the same as in Example 1, except that the reaction temperature is set to 500°C and kept constant.

[0038] Maintain the temperature at 500℃±5℃. The pure chlorine gas flow rate is 80 mL / min. The total reaction time is 30 minutes. Collect the product and treat the residue as in Example 1.

[0039] Results: The crude TiCl4 product yielded 33.2 g, with a yield of approximately 80.94%. X-ray diffraction (XRD) analysis of the chlorination residue showed that the diffraction peaks of the feldspar phase were still obvious, and no obvious CaCl2 or MgCl2 crystalline phases were detected.

[0040] Example 3 Charging and Heating: The procedure is the same as in Example 1, except that the reaction temperature is set to 650℃ and kept constant. Chlorination Reaction: The temperature is maintained at 650℃±5℃. The pure chlorine gas flow rate is 100 mL / min. The total reaction time is 1 hour. Product Collection and Residue Treatment: The procedure is the same as in Example 1.

[0041] Results: The crude TiCl4 product yielded 34.9 g, with a yield of approximately 85.1%. X-ray diffraction (XRD) analysis of the chlorination residue showed that the diffraction peaks of the feldspar phase were still obvious, and no obvious CaCl2 or MgCl2 crystalline phases were detected.

[0042] The above three embodiments demonstrate that the method of the present invention can operate effectively within the temperature range of 350℃ to 650℃ as defined by the method of the present invention, achieving TiC. x O y Selective chlorination.

[0043] Based on the preferred embodiment, specific analysis and test results were obtained. The microstructure and phase composition before the reaction are described in [reference needed]. Figure 3The analysis was performed using a scanning electron microscope (SEM, Sigma 500, Carl Zeiss AG, Jena, Germany) and a mineral liberation analyzer (MLA650F). Contains TiC x O y The microstructure and phase composition of the slag particles were characterized. For the microstructure and phase composition after the reaction, please refer to [reference needed]. Figure 4 The microstructure and phase composition of the chlorination residue particle profile were characterized using a scanning electron microscope (SEM, Sigma 500, Carl Zeiss AG, Jena, Germany) and a mineral dissociation analyzer (MLA650F).

[0044] The English labels in the image are Melilite, Chlorinated Melilite, and TiC, respectively. x O y (Titanium oxycarbide) and metallic iron. The vertical axis represents the area fraction, which refers to the percentage of the area occupied by the phase in the observed cross section. It can be equivalently regarded as a representation of its volume fraction.

[0045] Figure 3 and Figure 4 Testing and characterization methods: In order to understand the characteristics of the phase in detail and explore the TiC-containing phase... x O y The morphology and phase transformation of TiCl4 produced from slag were investigated. The slag particles before and after the reaction were dispersed and cured with epoxy resin. After the epoxy resin was completely solidified, the particles were polished to expose the cross-sectional structure. The cross-sectional structure, phase composition and distribution of the particles before and after the reaction were then analyzed using a scanning electron microscope and a mineral dissociation analyzer.

[0046] Figure 3 For TiC x O y The microstructure and phase distribution inside the slag particles Figure 3 (a) contains TiC x O y The microscopic morphology inside the slag particles is shown in 3(c). Figure 3 (b) and (d) are respectively Figure 3 Phase distribution diagrams corresponding to (a) and (c) Figure 3 (e) contains TiC x O y The area percentage of each phase in the slag. For example... Figure 3As shown in (a)~(e), containing TiC x O y The slag particles are mainly composed of feldspar, titanium oxide carbon, and a small amount of metallic iron, with feldspar accounting for 71.18% of the particle matrix. It contains TiC. x O y The slag contained a large number of fine white particles, which, according to MLA phase analysis, are TiC. x O y Its area fraction is 26.44%. It contains TiC. x O y TiC in slag x O y The phase is dispersed in a complex oxide containing TiC. x O y The slag also contains iron beads, with an area fraction of 2.39%.

[0047] Figure 4 The microstructure and phase distribution inside the chlorinated residue particles are shown. Figure 4 (a) shows the microstructure of the chlorination residue particles, and its magnified part is shown in 4(c). Figure 4 (b) and (d) are respectively Figure 4 Phase distribution diagrams corresponding to (a) and (c) Figure 4 (e) represents the area percentage of each phase in the chlorination residue. For example... Figure 4 As shown in (a)~(e), the main phases of the chlorinated residue particles are feldspar, chlorinated feldspar, and TiC. x O y Composed of a small amount of metallic iron, feldspar remains the main phase of the chloride residue particles, with a measured area fraction of 78.13%, and TiC... x O y Similar to metallic iron, it is distributed inside the feldspar. However, the difference is that chlorinated feldspar has been added to the pore area at the edge of the chlorinated residue particles, and its area fraction was measured to be 13.18%.

[0048] according to Figure 3 and 4 Compared with TiC x O y TiC inside slag and chlorination residue particles x O y The area fraction decreased from 26.44% to 7.38%, and the area fraction of metallic iron decreased from 3.65% to 1.31%. Residual TiC remained inside the chloride residue particles. x O y And metallic iron, because they are encased in a large amount of feldspar, which prevents them from reacting with chlorine.

[0049] In summary, TiC-containing x Oy After reacting slag with chlorine gas to produce TiCl4, it contains TiC. x O y TiC inside slag and chlorination residue particles x O y The area fraction decreased from 26.44% to 7.38%, while the area fraction of feldspar did not change significantly, achieving TiC. x O y Preferred selective chlorination. The edges of chlorinated residue particles are affected by TiC. x O y The reaction leaves behind pores, and the phase in the pore area is chlorinated feldspar, with TiC encased inside the feldspar. x O y It did not react with metallic iron. This invention can be widely applied to the extraction of titanium resources from perovskite-containing titanium slag or minerals in the Panzhihua-Xichang and Chengde regions of my country, and to the transformation of low-content perovskite-containing slag into TiC abroad. x O y Subsequently, this research will explore the field of selective chlorination extraction of titanium resources with chlorine gas, and can also provide technical reference for the comprehensive utilization of low-grade associated resources.

[0050] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular number.

[0051] It should be understood that, as used herein, the singular form “a” is intended to include the plural form as well, unless the context clearly supports an exception. It should also be understood that, as used herein, “and / or” refers to any and all possible combinations of one or more of the associated listed items.

[0052] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0053] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of different aspects of the invention exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for the low-temperature selective chlorination of titanium tetrachloride from titanium-containing composite slag, characterized in that, include: S1 provides titanium-containing composite slag, the titanium-containing composite slag comprising TiC x O y Multiphase solid materials containing both diatomite and feldspar phases; S2 Place the titanium-containing composite slag in a reactor and heat it to 350℃~700℃; S3 introduces chlorine-containing gas into the reactor to conduct a selective chlorination reaction with the titanium-containing composite slag. S4 collects and condenses the gas produced during the reaction to obtain TiCl4 product, and discharges the chlorination residue after the reaction.

2. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, In S1, the titanium-containing composite slag also includes a metallic iron phase.

3. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, In step S2, the titanium-containing composite slag is heated to 350°C to 650°C.

4. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, In S3, the selective chlorination reaction takes 15 minutes to 3 hours.

5. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, In S3, the chlorine-containing gas is chlorine or a mixture of chlorine and an inert gas, wherein the volume concentration of chlorine is not less than 50%.

6. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, The chlorine-containing gas comes from liquid chlorine evaporation gas and factory circulating chlorine gas.

7. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, In S1, the titanium-containing composite slag is obtained by carbonization-reduction smelting of titanium slag containing perovskite.

8. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, The yellow feldspar phase is at least one of aluminum yellow feldspar or magnesium yellow feldspar.

9. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, In S3, the reaction conditions are controlled so that the area fraction of the feldspar phase in the residue after the reaction remains above 60% of that before the reaction.

10. The method for producing titanium tetrachloride from titanium-containing composite slag by low-temperature selective chlorination according to claim 1, characterized in that, The reactor is a fixed-bed reactor or a fluidized-bed reactor.

Images