Fused salt system for titanium slag chlorination and regulation and control method thereof

Abstract

The invention relates to the technical field of metallurgical engineering, and provides a molten salt system for titanium slag chlorination and a regulation and control method thereof.The molten salt system comprises alkali metal chloride, alkaline-earth metal chloride, FeCl2, FeCl3 and MnCl2, the alkaline-earth metal chloride, FeCl2, FeCl3 and MnCl2 are components generated in situ in the titanium slag chlorination process, and the alkaline-earth metal chloride, FeCl2, FeCl3 and MnCl2 are components generated in situ in the titanium slag chlorination process. The alkali metal chloride is an exogenous component supplemented for adjusting the liquid-solid ratio of the molten salt system, and the molten salt system is constructed to improve the chlorination rate of the titanium slag by maintaining the liquid-solid ratio of the molten salt system to be not lower than 3: 2. According to the method, efficient and stable chlorination of the titanium slag is achieved.

Description

Technical Field

[0001] This invention relates to the field of metallurgical engineering technology, and in particular to a molten salt system for chlorinating titanium slag and its control method. Background Technology

[0002] In the process of preparing titanium tetrachloride by molten salt chlorination, titanium-containing raw materials undergo chlorination within the reaction system. Most of the titanium components are converted into the target product, titanium tetrachloride, while impurities such as calcium and magnesium in the raw materials are simultaneously chlorinated, generating alkaline earth metal chlorides such as calcium chloride and magnesium chloride, which dissolve in the molten salt to form the main liquid phase component of the molten salt system. At the same time, small amounts of difficult-to-chlorinate compounds present in the raw materials, such as silicon and aluminum compounds, remain in solid form during the chlorination process, forming solid impurities. As the chlorination process continues, alkaline earth metal chlorides and solid impurities accumulate in the molten salt system. When the concentration of these components accumulates to a certain level, it significantly negatively impacts the mass transfer process of the reactants within the molten salt system and the overall heat transfer efficiency of the system, leading to a substantial decrease in titanium chlorination efficiency. To maintain the continuous and stable operation of the chlorination process, existing technologies typically involve draining some of the old molten salt and replenishing it with fresh molten salt.

[0003] However, this technical approach has clear limitations: there is currently a lack of key evaluation indicators for the performance degradation of molten salt systems, as well as a lack of precise control methods based on these indicators. Specifically, existing technologies cannot determine when salt discharge is needed or how much salt should be discharged and replenished, making production operations reliant on experience-based judgment and making it difficult to achieve efficient and stable chlorination of titanium-containing materials, especially high-calcium-magnesium-titanium slag.

[0004] Therefore, there is an urgent need to provide a molten salt system with clear criteria for judging deterioration and a quantitative control method that is linked to it. Summary of the Invention

[0005] The lack of key evaluation indicators for the deterioration of molten salt system performance in existing technologies, as well as the absence of precise control methods based on these indicators, makes production operations reliant on experience-based judgment, making it difficult to achieve efficient and stable chlorination of titanium-containing materials, especially high-calcium magnesium titanium slag.

[0006] According to a first aspect of the present invention, a molten salt system for chlorinating titanium slag is provided, comprising: alkali metal chloride, alkaline earth metal chloride, FeCl2, FeCl3, and MnCl2, wherein the alkaline earth metal chloride, FeCl2, FeCl3, and MnCl2 are components generated in situ during the chlorination process of titanium slag, the alkali metal chloride is an exogenous component added to adjust the liquid-solid ratio of the molten salt system, and the molten salt system is configured to improve the chlorination rate of titanium slag by maintaining its liquid-solid ratio at no less than 3:2, wherein the liquid-solid ratio is dimensionless.

[0007] In some embodiments, the alkali metal chloride includes one or more mixtures of NaCl, KCl, LiCl, and CsCl.

[0008] In some embodiments, the liquid phase of the molten salt system includes the alkali metal chloride, alkaline earth metal chloride, FeCl2, FeCl3, and MnCl2, and the solid phase of the molten salt system includes chlorinated residue, unchlorinated titanium slag, and carbonaceous materials.

[0009] In some embodiments, the molten salt system is used to chlorinate one or more of acid-soluble titanium slag, high-titanium slag with a titanium dioxide content greater than 85%, or rutile.

[0010] According to a second aspect of the present invention, the present invention also provides a method for controlling a molten salt system for titanium slag chlorination, comprising: Step a: During the chlorination process of titanium slag molten salt, monitor the liquid-to-solid ratio of the molten salt system; Step b: When the liquid-to-solid ratio of the molten salt system is detected to be lower than 3:2, molten salt accounting for 5-25% of the total mass of the molten salt system is discharged from the molten salt system, and then alkali metal chloride accounting for 5-20% of the total mass of the molten salt system is added to the molten salt system to restore the liquid-to-solid ratio of the molten salt system to a level not lower than 3:2.

[0011] In some embodiments, the method for monitoring the liquid-solid ratio of the molten salt system in step a includes hot direct filtration separation or water washing separation.

[0012] In some embodiments, the molten salt discharged in step b accounts for 10-15% of the total mass of the molten salt system.

[0013] In some embodiments, the alkali metal chloride added to the molten salt system in step b accounts for 10-15% of the total mass of the molten salt system.

[0014] In some embodiments, in step a, the chlorination temperature of the titanium slag molten salt chlorination process is above the melting point and below the boiling point of the molten salt system.

[0015] In some embodiments, in step a, the chlorination temperature of the titanium slag molten salt chlorination process is 500-1000℃.

[0016] The above-mentioned molten salt system for titanium slag chlorination and its control method clarify the key evaluation index for the performance deterioration of the molten salt system, and provide quantitative and precise control methods for the evaluation index, which is conducive to achieving efficient and stable chlorination of titanium slag.

[0017] Specifically, by defining that the molten salt system contains alkali metal chlorides, alkaline earth metal chlorides, FeCl2, FeCl3, and MnCl2, and clearly differentiating the components generated in-situ from the exogenous components added to adjust the liquid-solid ratio, a reaction medium with a clear composition and defined functions is constructed. Among them, the added alkali metal chlorides, as key regulating components, actively maintain the physical properties of the molten salt system, laying a material foundation for subsequent precise regulation. The liquid-solid ratio is creatively introduced as a direct and quantifiable core parameter, specifically defining and maintaining a threshold where the liquid-solid ratio is not lower than 3:2, solving the problem of the lack of a key evaluation index for performance deterioration, providing an operation basis for judging when salt discharge is required, and avoiding the current situation of relying on empirical judgment. This application also provides a regulation method supporting the molten salt system for titanium slag chlorination, further defining that when the liquid-solid ratio is lower than 3:2, operation steps including discharging 5-25% of the total mass of the molten salt and adding 5-20% of alkali metal chlorides are carried out. This series of quantitative operations overcome the problem of how to determine the amount of salt discharge and salt addition, ensuring that the molten salt system can quickly and reliably recover to a level not lower than 3:2, thus restoring the efficient mass transfer and heat transfer capabilities, and ultimately achieving the stable maintenance of a high chlorination rate of titanium slag.

[0018] The entire solution of this application is closely linked, forming a complete technical loop from system construction to deterioration evaluation and then to precise regulation, significantly improving the stability and efficiency of the molten salt chlorination process. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other embodiments can be obtained based on these drawings without creative efforts.

[0020] Figure 1 It is a flowchart of a regulation method for a molten salt system for titanium slag chlorination provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The following will further describe the embodiments of the present disclosure in detail in conjunction with the drawings and examples. The detailed description and drawings of the following examples are used to exemplarily illustrate the principles of the present disclosure, but cannot be used to limit the scope of the present disclosure. The present disclosure can be implemented in many different forms, not limited to the specific embodiments disclosed herein, but including all technical solutions falling within the scope of the claims.

[0022] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as exemplary only and not as limiting.

[0023] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. Terms such as "including" or "contains" mean that the element preceding the word covers the element listed after the word, and do not exclude the possibility of covering other elements as well.

[0024] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0025] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.

[0026] It should be understood that the embodiments of the invention shown in the exemplary embodiments are merely illustrative. Although only a few embodiments have been described in detail in this invention, those skilled in the art will readily recognize that various modifications are possible without substantially departing from the teachings of the invention. Accordingly, all such modifications should be included within the scope of the invention. Other substitutions, modifications, variations, and deletions can be made to the design, operating conditions, and parameters of the following exemplary embodiments without departing from the spirit of the invention.

[0027] According to a first aspect of the present invention, a molten salt system for chlorinating titanium slag is provided, comprising: alkali metal chloride, alkaline earth metal chloride, FeCl2, FeCl3, and MnCl2, wherein the alkaline earth metal chloride, FeCl2, FeCl3, and MnCl2 are components generated in situ during the chlorination process of titanium slag, and the alkali metal chloride is an exogenous component added to adjust the liquid-solid ratio of the molten salt system. The molten salt system is configured to improve the chlorination rate of titanium slag by maintaining its liquid-solid ratio at no less than 3:2, wherein the liquid-solid ratio is dimensionless.

[0028] The aforementioned molten salt system for titanium slag chlorination, by limiting its composition to include alkali metal chlorides, alkaline earth metal chlorides, FeCl2, FeCl3, and MnCl2, and clearly distinguishing between in-situ generated components and exogenous components added to adjust the liquid-solid ratio, constructs a reaction medium with a clear composition and defined function. Among these, the added alkali metal chlorides, as key regulating components, actively maintain the physical properties of the molten salt system, laying the material foundation for subsequent precise control. The innovative introduction of the liquid-solid ratio as a direct and quantifiable core parameter, specifically limiting it to a threshold of no less than 3:2, solves the problem of lacking key indicators for performance degradation, providing an operational basis for determining when salt discharge is necessary and avoiding reliance on experience-based judgments. By clarifying the key indicators for performance degradation of the molten salt system, a quantitative and precise control method for these indicators is provided, which is conducive to achieving efficient and stable chlorination of titanium slag.

[0029] In some embodiments, alkaline earth metal chlorides include CaCl2, MgCl2, etc. In-situ generation refers to the direct conversion of impurity components within the raw materials into products during a high-temperature chlorination reaction conducted under a chlorine atmosphere using titanium slag (typically containing components such as TiO2, CaO, MgO, FeO, and MnO) and a carbonaceous reducing agent (such as petroleum coke) as raw materials. For example, CaO and MgO are chlorinated to form CaCl2 and MgCl2, iron oxides are chlorinated and exist in the form of FeCl2 and FeCl3, and manganese oxides are chlorinated to form MnCl2. These components collectively constitute the basic liquid phase of the molten salt system.

[0030] As a feasible embodiment, alkali metal chloride refers to an exogenous component added to adjust the liquid-to-solid ratio of the molten salt system. Exogenous means that this component is not generated by the chlorination reaction of the current batch of titanium slag raw material, but is actively added to the reaction system from the outside. Its core function is to adjust the physical properties of the entire molten salt system, especially the liquid-to-solid ratio. The liquid-to-solid ratio, i.e., the ratio of the total mass of liquid phase substances to the total mass of solid phase substances in the molten salt system, is a key parameter affecting the mass transfer efficiency of reactants. It can be understood that the units for both the total mass of liquid phase substances and the total mass of solid phase substances in the molten salt system can be kg; therefore, this liquid-to-solid ratio is dimensionless. By adding alkali metal chloride, the liquid phase proportion can be significantly increased, diluting the solid phase impurities accumulated due to the reaction (such as chlorination residue, incompletely chlorinated titanium slag particles, unreacted carbonaceous materials, etc.), thereby maintaining the good fluidity of the molten salt.

[0031] Specifically, by constructing the molten salt system to maintain a liquid-to-solid ratio of at least 3:2, the chlorination rate of titanium slag can be significantly improved. When the liquid-to-solid ratio is below this threshold, excessive enrichment of solid impurities leads to viscous molten salt, hindering the diffusion of chlorine and reaction products, and causing a sharp decrease in the chlorination reaction rate. Maintaining a liquid-to-solid ratio of at least 3:2 ensures that the reaction system has suitable hydrodynamic conditions, thereby achieving a highly efficient and stable chlorination process.

[0032] According to several embodiments of the present invention, the alkali metal chloride includes one or more mixtures of NaCl, KCl, LiCl, and CsCl. For example, in actual industrial production, NaCl and KCl are particularly commonly used choices due to a combination of cost and effectiveness considerations. They can effectively lower the eutectic melting point of the molten salt system and expand its suitable liquid phase range for operation.

[0033] According to several embodiments of the present invention, the liquid phase of the molten salt system includes alkali metal chlorides, alkaline earth metal chlorides, FeCl2, FeCl3, and MnCl2, and the solid phase of the molten salt system includes chloride residues, unchlorinated titanium slag, and carbonaceous materials. The liquid phase of the molten salt system is formed by the co-melting of all chlorides (alkali metal chlorides, alkaline earth metal chlorides, FeCl2, FeCl3, and MnCl2). The solid phase mainly originates from the reaction process and includes, but is not limited to: incompletely reacted chloride residues (mainly high-melting-point oxides or chlorides such as silicon and aluminum), unchlorinated titanium slag particles due to encapsulation or reaction kinetic limitations, and excess carbonaceous materials, such as petroleum coke.

[0034] According to several embodiments of the present invention, a molten salt system is used to chlorinate one or more of acid-soluble titanium slag, high-titanium slag with a titanium dioxide content greater than 85%, or rutile. For example, acid-soluble titanium slag typically contains high levels of calcium and magnesium impurities, while high-titanium slag is enriched in TiO2, and rutile can be natural or synthetic. This molten salt system exhibits good adaptability to these titanium-containing raw materials, effectively treating the high calcium and magnesium impurities and efficiently converting the titanium in them into titanium tetrachloride.

[0035] According to a second aspect of the present invention, the present invention also provides a method for controlling a molten salt system for titanium slag chlorination, comprising: Step a: During the chlorination process of titanium slag molten salt, monitor the liquid-to-solid ratio of the molten salt system; Step b: When the liquid-to-solid ratio of the molten salt system is detected to be lower than 3:2, molten salt accounting for 5-25% of the total mass of the molten salt system is discharged from the molten salt system. Then, alkali metal chloride accounting for 5-20% of the total mass of the molten salt system is added to the molten salt system to restore the liquid-to-solid ratio of the molten salt system to a level not lower than 3:2.

[0036] Step a involves continuously or intermittently monitoring the liquid-to-solid ratio of the molten salt system during the titanium slag chlorination process. Step b is the control execution step. When the liquid-to-solid ratio of the molten salt system is detected to be lower than 3:2, it indicates that the system has begun to deteriorate and the mass transfer efficiency has decreased, triggering the control operation. This operation includes two consecutive actions: First, 5-25% of the old molten salt, accounting for 5% of the total mass of the molten salt system, is removed from the molten salt system. The purpose of removing the salt is to directly remove the enriched solid impurities and some high-concentration alkaline earth metal chlorides in the system. Then, 5-20% of the total mass of the molten salt system, consisting of alkali metal chlorides (such as NaCl), is added to the system. The purpose of adding the alkali metal chloride is to quickly replenish the liquid phase volume, dilute the remaining solid impurities, and thus rapidly increase the liquid-to-solid ratio of the system and restore it to a normal level of not less than 3:2.

[0037] The aforementioned method for controlling the molten salt system for titanium slag chlorination is compatible with the molten salt system for titanium slag chlorination provided in this application. It further specifies that when the liquid-to-solid ratio is below 3:2, the operation steps include discharging 5-25% of the total mass of molten salt and adding 5-20% of alkali metal chloride. This series of quantitative operations overcomes the difficulty of determining the amount of salt to be discharged and added, ensuring that the molten salt system can be quickly and reliably restored to a level not lower than 3:2, thereby restoring efficient mass and heat transfer capabilities and ultimately achieving stable maintenance of the high chlorination rate of titanium slag.

[0038] According to several embodiments of the present invention, the method for monitoring the liquid-solid ratio of the molten salt system in step a includes a hot direct filtration separation method or a water washing separation method. As a specific embodiment, the hot direct filtration separation method is preferred. Specifically, during the molten salt chlorination reaction, a certain amount of high-temperature molten salt sample is extracted online or offline from the reactor using a specific device (e.g., a stainless steel filter with a high-temperature resistant metal filter). While maintaining the sample temperature above the molten salt's freezing point, pressure is rapidly applied or gravity is used to allow the liquid phase to pass through the filter, while the solid particles are retained. The real-time liquid-solid ratio can be calculated by weighing the obtained liquid phase mass and solid phase mass separately. This method can most accurately reflect the physical properties of the molten salt under reaction conditions. As another feasible embodiment, the water washing separation method involves cooling the extracted molten salt sample, dissolving all soluble chloride liquid phase components in water, filtering, and then separately measuring the mass of the insoluble solid residue and the mass of the dissolved salt obtained by evaporating the solution to calculate the liquid-solid ratio. This method is simple to operate, but may introduce slight errors due to the hydrolysis of some components.

[0039] According to several embodiments of the present invention, the molten salt discharged in step b accounts for 10-15% of the total mass of the molten salt system.

[0040] According to several embodiments of the present invention, the alkali metal chloride added to the molten salt system in step b accounts for 10-15% of the total mass of the molten salt system.

[0041] For example, in one configuration, 12% of the old molten salt can be discharged and 12% of fresh NaCl can be added. This range is an optimized range verified through extensive experiments, achieving a good balance between effectively restoring system performance and maintaining production continuity while controlling raw material consumption.

[0042] According to several embodiments of the present invention, in step a, the chlorination temperature of the titanium slag molten salt chlorination process is above the melting point and below the boiling point of the molten salt system. The chlorination temperature should be controlled above the melting point and below the boiling point of the molten salt system to ensure that the molten salt is in a molten liquid state and does not volatilize in large quantities.

[0043] According to several embodiments of the present invention, in step a, the chlorination temperature of the titanium slag molten salt chlorination process is 500-1000℃. As a specific embodiment, for a molten salt system mainly composed of NaCl-MgCl2-CaCl2, the chlorination temperature is generally preferably controlled between 700-850℃. For example, when treating acid-soluble titanium slag, the temperature can be controlled at around 750℃; when treating high-grade rutile, due to differences in reactivity, the temperature can be appropriately increased to around 850℃. This temperature range ensures a sufficiently high reaction rate while maintaining the physicochemical stability of the molten salt.

[0044] To further understand the molten salt system for titanium slag chlorination and its control method provided by the present invention, the following detailed description is provided in specific embodiments.

[0045] Example 1 Molten salt chlorination was carried out using acid-soluble titanium slag with a TiO2 content of 74% and petroleum coke as raw materials, with the chlorination temperature controlled at 700-800℃. The molten salt system formed during this process mainly consisted of NaCl, MgCl2, CaCl2, FeCl2, MnCl2, and FeCl3, where NaCl was the added alkali metal chloride, and the remaining components were chlorination products generated in situ during the chlorination of the acid-soluble titanium slag. A stainless steel filtration device was used to monitor the liquid-to-solid ratio of the molten salt system. When the liquid-to-solid ratio reached 2.8:2, i.e., below the 3:2 threshold, it indicated a deterioration in the performance of the molten salt system, a significant decrease in the chlorination efficiency of the acid-soluble titanium slag, and a reduction in the titanium chlorination rate to approximately 85%. At this point, a control operation was performed: 10% of the total mass of molten salt was discharged from the system, and then 10% of the total mass of NaCl was added back into the system. After the adjustment operation, the liquid-to-solid ratio of the molten salt system was restored to 4.1:2 (higher than the liquid-to-solid ratio of 3:2), and the chlorination rate of titanium was increased to 95%, achieving efficient and stable chlorination of acid-soluble titanium slag.

[0046] Example 2 Molten salt chlorination was carried out using high-titanium slag with a TiO2 content of 85% and petroleum coke as raw materials, with the chlorination temperature controlled at 800-850℃. The composition of the molten salt system formed during this process was similar to that in Example 1, mainly consisting of NaCl, MgCl2, CaCl2, FeCl2, MnCl2, and FeCl3, where NaCl was the added alkali metal chloride, and the remaining components were chlorination products generated in situ during the high-titanium slag chlorination process. A stainless steel filter was used to monitor the liquid-to-solid ratio of the molten salt system. When the liquid-to-solid ratio of the molten salt system reached 2.5:2 (i.e., below 3:2), it indicated a significant deterioration in the performance of the molten salt system, a significant decrease in the chlorination efficiency of the high-titanium slag, and a reduction in the titanium chlorination rate to approximately 76%. Immediately, a control operation was performed: 15% of the total mass of molten salt was discharged from the molten salt system, and then 10% of the total mass of NaCl was added to the system. After the adjustment operation, the liquid-solid ratio of the molten salt system was restored to 3.7:2 (higher than 3:2), and the chlorination rate of titanium in the high-titanium slag increased to 96%, achieving efficient and stable chlorination of the high-titanium slag.

[0047] Example 3 Molten salt chlorination was performed using rutile with a TiO2 content of 92% and coke as raw materials, with the chlorination temperature controlled at 900-950℃. The molten salt system formed during this process mainly consisted of KCl, MgCl2, CaCl2, and FeCl3, where KCl was the added alkali metal chloride, and the remaining components were chlorination products generated in situ during rutile chlorination. The liquid-to-solid ratio of the molten salt system was monitored using a water washing separation method. When the liquid-to-solid ratio of the molten salt system reached 2.8:2 (i.e., below 3:2), it indicated a deterioration in the performance of the molten salt system, with a significant decrease in the chlorination efficiency of titanium, dropping to approximately 82%. At this point, a control operation was performed: 20% of the total mass of molten salt was removed from the system, and then 15% of the total mass of KCl was added to the system. After the control operation, the liquid-to-solid ratio of the molten salt system was restored to 3.8:2 (above 3:2), and the chlorination rate of titanium in the rutile increased to 94%, achieving efficient and stable chlorination of rutile.

[0048] Example 4 Molten salt chlorination was carried out using high-titanium slag with a TiO2 content of 90% and petroleum coke as raw materials. To verify the effectiveness of the method at relatively low temperatures, the chlorination temperature was controlled at 500-600℃. Under these conditions, the molten salt system mainly consisted of NaCl-MgCl2-CaCl2-FeCl2-MnCl2-FeCl3, where NaCl was a supplementary alkali metal chloride. The liquid-to-solid ratio was monitored using a hot direct filtration separation method. When the liquid-to-solid ratio dropped to 2.9:2, the system showed signs of deterioration, with the titanium chlorination rate decreasing to 88%. At this point, a control operation was performed: 5% of the total mass of molten salt was removed from the molten salt system, and then 5% of the total mass of NaCl was added back into the system. After the control operation, the liquid-to-solid ratio of the molten salt system was restored to 3.5:2, and the titanium chlorination rate increased to 93%, indicating that even at lower chlorination temperatures, the removal and addition of salt at the lower limit ratio can effectively restore the system performance.

[0049] Example 5 Rutile with a TiO2 content of 95% and coke were used as raw materials. To verify the effectiveness of the method at higher temperatures, the chlorination temperature was controlled at 980-1000℃, close to the upper limit of the range described in claim 10. At this temperature, the molten salt system mainly consisted of KCl-MgCl2-CaCl2-FeCl3, where KCl was the added alkali metal chloride. The liquid-solid ratio was monitored using a water washing separation method. When the liquid-solid ratio dropped to 2.6:2, the system deteriorated severely, and the titanium chlorination rate plummeted to 70%. At this point, a control operation was performed: 25% of the total mass of molten salt was removed from the molten salt system, and then 20% of the total mass of KCl was added to the system. After this large-scale replacement operation, the liquid-solid ratio of the molten salt system recovered to 3.9:2, and the titanium chlorination rate significantly increased to 92%, indicating that for severely deteriorated systems, the upper limit ratio of salt removal and replenishment is effective and necessary.

[0050] Examples 1-5 above all successfully achieved efficient and stable chlorination of titanium slag. Despite significant differences in the titanium-containing raw materials used—ranging from acid-soluble titanium slag with 74% TiO2 to rutile with 95% TiO2, the chlorination temperature from a lower limit of 500-600℃ to a higher limit of 980-1000℃, and the intensity of the control operation (salt removal / salt replenishment from 5% to 25% / 20%)—the molten salt system and control method of this invention were effective under all conditions. This demonstrates that the technical solution has strong adaptability to different quality raw materials and a wide range of process conditions, exhibiting high technical robustness.

[0051] Meanwhile, a liquid-to-solid ratio below 3:2 was consistently used as the sole and definitive criterion for system deterioration and the need for intervention. Regardless of whether the initial chlorination rate before system deterioration was 85%, 76%, 82%, 88%, or 70%, efficiency significantly decreased once the liquid-to-solid ratio fell below this threshold. However, by adjusting and restoring the liquid-to-solid ratio to at least 3:2, the chlorination rate consistently stabilized above 92%. This consistent verification demonstrates that a liquid-to-solid ratio of 3:2 as the critical threshold for the deterioration of molten salt chlorination performance has universal guiding significance, resolving the core issue of the lack of a clear evaluation standard in existing technologies.

[0052] Meanwhile, Examples 1-5 demonstrate that the specific ratio of salt removal to salt replenishment is not fixed but can be adjusted according to the severity of system deterioration. For example, for slight deterioration (liquid-to-solid ratio 2.9:2, Example 4), the lower limit (5%) adjustment is sufficient for recovery; for severe deterioration (liquid-to-solid ratio 2.6:2, Example 5), the upper limit (25% salt removal, 20% salt replenishment) requires strong intervention. This indicates that the 5-25% and 5-20% ranges given in this application are effective quantitative control intervals verified in practice. Those skilled in the art can perform precise operations within these ranges based on monitoring results, solving the problem of prior art where control relies on experience and lacks quantitative basis.

[0053] Meanwhile, the molten salt systems in Examples 1-5 all contain alkali metal chlorides (NaCl or KCl), alkaline earth metal chlorides, FeCl2, FeCl3, and MnCl2 as defined in this application, and clearly distinguish between in-situ generated and exogenously added components. This verifies the feasibility of constructing a controllable, high-performance molten salt system by introducing exogenous alkali metal chlorides, a system different from existing systems that are passively formed solely by reaction products.

[0054] The embodiments of this disclosure have now been described in detail. To avoid obscuring the concept of this disclosure, some details known in the art have not been described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein based on the above description.

[0055] While specific embodiments of this disclosure have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of this disclosure. Those skilled in the art should understand that modifications can be made to the above embodiments or equivalent substitutions can be made to some technical features without departing from the scope and spirit of this disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in the various embodiments can be combined in any manner.

Claims

1. A molten salt system for chlorination of titanium slag, characterized by, The application relates to a method for chlorinating acid-soluble titanium slag, high-titanium slag or rutile, and belongs to the technical field of titanium smelting. The alkali metal chloride includes one or more of NaCl, KCl, LiCl and CsCl.

2. The molten salt system for titanium slag chlorination according to claim 1, characterized in that, The liquid phase of the molten salt system includes the alkali metal chloride, the alkali earth metal chloride, FeCl2, FeCl3 and MnCl2, and the solid phase of the molten salt system includes chlorinated residues, un-chlorinated titanium slag and carbon-containing materials.

3. The molten salt system for chlorination of titanium slag according to claim 1, characterized in that, The molten salt system is used for chlorinating one or more of acid-soluble titanium slag, high-titanium slag with a titanium dioxide content of more than 85% or rutile.

4. The molten salt system for chlorination of titanium slag according to claim 1, wherein, The application relates to a method for chlorinating acid-soluble titanium slag, high-titanium slag or rutile, and belongs to the technical field of titanium smelting.

5. A method for regulating a molten salt system for titanium slag chlorination, characterized by, Step a: monitoring the liquid-solid ratio of the molten salt system during the process of molten salt chlorination of the titanium slag; Step b: when the liquid-solid ratio of the molten salt system is monitored to be lower than 3:2, discharging 5-25% of the total mass of the molten salt in the molten salt system, and then adding 5-20% of the total mass of the molten salt system of alkali metal chloride into the molten salt system to restore the liquid-solid ratio of the molten salt system to a level of not lower than 3:

2. The method for monitoring the liquid-solid ratio of the molten salt system in step a includes a hot-state direct filtration separation method or a water washing separation method.

6. The method for regulating the molten salt system for titanium slag chlorination according to claim 5, characterized in that, The molten salt discharged in step b accounts for 10-15% of the total mass of the molten salt system.

7. The method for regulating the molten salt system for titanium slag chlorination according to claim 5, characterized in that, The alkali metal chloride added into the molten salt system in step b accounts for 10-15% of the total mass of the molten salt system.

8. The method for regulating the molten salt system for titanium slag chlorination according to claim 5, characterized in that, In step a, the chlorination temperature of the process of molten salt chlorination of the titanium slag is higher than the melting point and lower than the boiling point of the molten salt system.

9. The method for regulating the molten salt system for titanium slag chlorination according to claim 5, characterized in that, In step a, the chlorination temperature of the process of molten salt chlorination of the titanium slag is 500-1000 DEG C.

10. The method for regulating the molten salt system for titanium slag chlorination according to claim 5, characterized in that, ​

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