Magnesium refining agent, preparation method thereof and magnesium refining method

Abstract

The invention relates to the technical field of non-ferrous metal smelting, in particular to a magnesium refining agent, a preparation method thereof and a magnesium refining method, the refining agent is composed of, by mass, 30-45% of MgCl2, 35-45% of NaCl, 15-25% of CaCl2 and 2-5% of CaF2, and the purity and impurity content of all the components are strictly required. The preparation method comprises the following steps: pretreating a crucible, adding the raw materials in proportion step by step, melting and uniformly mixing at 750-850 DEG C to obtain mixed molten salt, cooling, crushing, grinding into particles, and sealing and storing. And during refining, a melting refining agent and crude magnesium are added into equipment according to the proportion of (4-5): 3, heat preservation is conducted at the temperature of 690-750 DEG C, after the crude magnesium is added, a particle refining agent is sprayed, and refining is conducted for 30-60 min under argon filling protection. The method overcomes the defects of incomplete impurity removal, narrow application range and the like in the prior art, and can effectively improve the magnesium purity and expand the high-end application of the magnesium.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of non-ferrous smelting, in particular to a magnesium refining agent, a preparation method thereof and a magnesium refining method. BACKGROUND

[0002] Titanium and titanium alloy have the characteristics of low density, high strength, corrosion resistance, good biocompatibility, etc., and are widely used in aerospace, deep-sea titanium materials, biological materials, chemical industry, nuclear power and other fields. Sponge titanium, as an important raw material for the preparation of titanium and titanium alloy, its impurity content determines the mechanical properties of titanium and titanium alloy. At present, in the process of producing sponge titanium by Kroll method, magnesium electrolysis is the core process for establishing magnesium-chlorine cycle in the production process of sponge titanium, and the quality of metal magnesium as an important raw material for its production directly affects the quality of sponge titanium. Therefore, improving the quality of magnesium reducing agent used in the production process of sponge titanium has become an important prerequisite for producing high-quality sponge titanium.

[0003] In order to improve the quality of magnesium reducing agent, in industrial production, a matching refining process is usually used to refine the magnesium reducing agent, and the principle is to remove part of the impurities by using flux refining and gravity sedimentation method.

[0004] The refining flux used in flux refining method is generally composed of MgCl2, KCl, NaCl, CaCl2, BaCl2 and CaF2,

[0005] The composition of the commonly used fluxing agent is: MgCl2 30-45%, NaCl 35-45%, CaCl2 15-25% and CaF2 2-5%, and generally it is a quaternary molten salt system of MgCl2-KCl-NaCl-CaCl2, but in the current industrial production, in order to save production cost, most enterprises have removed KCl which has relatively high price, and magnesium electrolysis and refining agent all use MgCl2-NaCl-CaCl2 ternary molten salt system, which leads to the fact that the original matching process is not suitable for the existing process.

[0006] In the research on the related patent technologies disclosed, it is found that the magnesium refining agent and its preparation method and the refining method of high-purity magnesium disclosed in CN109055779A have improved the magnesium refining process to a certain extent, but the refining agent has limitations in removing specific impurities in magnesium, and cannot quickly and completely remove impurities such as manganese ions, aluminum content, silicon content, iron content and zirconium ions in magnesium, which makes it difficult to achieve higher purity of refined magnesium, and affects the application of magnesium in some high-end fields with extremely strict purity requirements.

[0007] CN117248117A discloses a magnesium alloy refining agent, its preparation method and application, which is mainly aimed at the normal pressure smelting and refining of high modulus lithium-containing magnesium alloy. However, the content of calcium fluoride and magnesium chloride in the refining agent in this patent is relatively high, which is easy to react with lithium elements in the melt during smelting and refining. This not only introduces new impurity elements, but also consumes lithium elements in the melt, increases pollution, seriously affects the quality of the melt, and its application range is relatively narrow, only for specific high modulus lithium-containing magnesium alloy, and the refining effect for other types of magnesium alloy or pure magnesium is poor.

[0008] In summary, the defects of CN109055779A are that the magnesium refining agent provided by it cannot quickly and completely remove impurities such as manganese ions, aluminum, silicon, iron, zirconium ions in magnesium, so that the purity of refined magnesium is difficult to reach a higher standard, limiting the application of magnesium in high-end fields. The defects of CN117248117A are that the content of calcium fluoride and magnesium chloride in the refining agent is relatively high, which is easy to react with lithium elements in the melt, introduces new impurities and consumes lithium elements, affects the quality of the melt, and the application range is relatively narrow, only for specific high modulus lithium-containing magnesium alloy, and the refining effect for other types of magnesium alloy or pure magnesium is poor. SUMMARY

[0009] The purpose of the present application is to provide a magnesium refining agent and its preparation and a magnesium refining method to solve the problem that MgO, SiO2 and Al2O3 in the crude magnesium cannot be effectively removed in the refining process in the background art.

[0010] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0011] A magnesium refining agent, comprising the following components in mass percentage: MgCl2 composition 30-45%, NaCl composition 35-45%, CaCl2 composition 15-25%, and CaF2 composition 2-5%, the sum of the mass percentage of each component being 100%; wherein the MgCl2 composition contains MgCl2≥98.0%, MgO≤0.5%, Fe≤0.01%, and Ti≤0.008%; the NaCl composition contains NaCl≥99.1%, SO4 2- ≤0.3%, moisture≤0.05%, and water-insoluble substances≤0.05%; the CaCl2 composition contains CaCl2≥95.0%, SO4 2- ≤0.01%, moisture≤0.05%, and water-insoluble substances≤0.3%; and the CaF2 composition contains CaF2≥98.0%, CO3 2- ≤0.3%, SO4 2- ≤0.5%, Si≤0.53%, Fe≤0.07%, and H2O≤0.05%.

[0012] Preferably, the magnesium refining agent is composed of the following ingredients in mass percentage: MgCl2 32-40%, NaCl 40-45%, CaCl2 20-25%, and CaF2 3-5%.

[0013] Preferably, the magnesium refining agent is composed of the following ingredients in mass percentage: MgCl2 32-40%, NaCl 40-45%, CaCl2 20-25%, and CaF2 3-5%.

[0014] In another aspect, the present application also provides a method for preparing a magnesium refining agent, comprising the following steps:

[0015] a. According to the mass percentage of the magnesium refining agent in claim 1, the crucible is heated to 600°C and kept for 4 hours, then molten MgCl2 is added, followed by adding 1 / 2 amount of NaCl, and then the remaining 1 / 2 amount of NaCl and CaCl2 are alternately added to the crucible in multiple times. The temperature of the crucible is heated to 750-850°C until the material is completely melted, then CaF2 powder is added, and stirred and mixed to obtain a mixed molten salt;

[0016] b. The mixed molten salt obtained in step a is naturally cooled to room temperature, crushed to a block size of less than 100 mm, then transferred to a jaw crusher for crushing, and finally ground into particles with a diameter of less than 1.5 mm in a ball mill, and finally packaged, sealed and stored in a dry place.

[0017] Preferably, the crushing and grinding process in step b is carried out quickly in a dry environment.

[0018] In addition, the present application also provides a method for magnesium refining, comprising the following steps:

[0019] S1. The molten magnesium refining agent prepared in step a above is added to a refining furnace or crucible and kept at 690-750°C;

[0020] S2. The crude magnesium extracted from the electrolytic cell is added to the refining furnace or crucible in step S1;

[0021] S3. The magnesium refining agent prepared in step b above is sprayed and covered on the surface of the crude magnesium, argon is filled for protection, and refining is carried out for 30-60 min;

[0022] Preferably, the weight ratio of the magnesium refining agent to the crude magnesium is 4-5:3, and the crude magnesium is obtained by electrolysis using a MgCl2-NaCl-CaCl2 molten salt system electrolyte.

[0023] Preferably, argon is used as the spraying gas for spraying the refining agent in step S3.

[0024] As preferred, the spraying amount of the magnesium refining agent in step S3 is 0.6-1.0 kg per ton of crude magnesium.

[0025] As preferred, the refining is combined with the flux refining method and the settling refining method.

[0026] As preferred, the refining is continuous refining.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] The present application realizes multiple beneficial effects through the optimization of the component design, preparation process and refining method of the magnesium refining agent, and the specific analysis is as follows:

[0029] I. Solving the core technical problem and improving the refining effect

[0030] 1. Effectively removing key impurities

[0031] In view of the problem that MgO, SiO2, Al2O3 and other impurities are difficult to be effectively removed during the refining of crude magnesium in the prior art, the present application significantly improves the impurity removal capacity by adjusting the component and ratio of the refining agent (MgCl2 30-45%, NaCl 35-45%, CaCl2 15-25%, CaF2 2-5%).

[0032] High content of MgCl2 enhances the absorption capacity of K, Na and other alkali metals and MgO, CaO and other oxide impurities;

[0033] Reasonable proportion of CaF2 increases the surface tension between the flux and molten magnesium, promoting the separation of non-metallic impurities (especially magnesium particles wrapped by magnesium oxide) from magnesium;

[0034] Optimized CaCl2 content increases the covering density, which can adsorb impurities in liquid magnesium from top to bottom to form sediment, further reducing the impurity content.

[0035] According to the verification of the embodiments, the purity of magnesium after refining is increased from 99.93% to 99.96%, and the content of key impurities such as Si and Al is significantly reduced, meeting the requirements of 95A in the national standard GB / T 3499-2011.

[0036] 2. Adapt to existing process system

[0037] In the prior art, enterprises change the original MgCl2-KCl-NaCl-CaCl2 quaternary molten salt system to MgCl2-NaCl-CaCl2 ternary system to reduce costs, but the traditional refining agent does not match the system, resulting in poor refining effect. The present application directly uses a ternary molten salt refining agent, which perfectly matches the electrolyte system of the existing magnesium electrolysis process, solves the technical contradiction of "non-matching molten salt system", and ensures stable and efficient refining process.

[0038] II. Reduce production cost and process risk

[0039] 1. Reduce raw material cost

[0040] Compared with the quaternary system containing KCl, the present invention eliminates the high-priced KCl and uses inexpensive and readily available MgCl2, NaCl, and CaCl2 as the main components. All raw materials are conventional chemical products, which do not need special procurement, greatly reducing the preparation cost of the refining agent.

[0041] 2. Reduce the risk of introducing impurities

[0042] The use of KCl in the quaternary system may lead to the introduction of K and other impurities in the magnesium-chlorine cycle of titanium sponge production, affecting the quality of titanium sponge. The ternary system of the present invention avoids the introduction of K element, reducing the risk of impurities in subsequent titanium sponge production from the source, providing protection for the preparation of high-quality titanium sponge.

[0043] III. Optimize preparation and refining process, improve safety and operability

[0044] 1. Improve production environment and safety

[0045] In the preparation process, by designing the step of "adding molten MgCl2 first, then adding NaCl and CaCl2 in batches", the problem of generating a large amount of HCl smoke when solid CaCl2 is directly added to high-temperature molten salt is avoided, reducing the pollution to the site environment and the health damage to the operators.

[0046] 2. Ensure the stability of the refining agent

[0047] The crushing and grinding process of the refining agent requires rapid operation in a dry environment to avoid moisture absorption and hydrolysis, ensuring the chemical stability of the refining agent and ensuring its effective role in the refining process.

[0048] 3. Strong controllability of the refining process

[0049] During refining, the dual action mode of "adding molten refining agent at the bottom + spraying powder refining agent on the surface" is adopted, combined with argon protection and precise temperature control at 690~750℃, which not only prevents liquid magnesium from oxidizing and burning, but also improves the impurity removal efficiency through the synergistic effect of flux refining and gravity settling. The refining time only needs 30~60 minutes, which is suitable for industrialized continuous production.

[0050] IV. Promote the quality upgrading of the industrial chain

[0051] The application provides high-quality raw materials for downstream sponge titanium production by improving the purity of the magnesium reducing agent. Since the impurity content of the sponge titanium directly affects the mechanical properties of titanium and titanium alloys, the application of the application can indirectly improve the quality of titanium used in high-end fields such as aerospace, deep-sea titanium materials and biological materials, and has significant industrial value.

[0052] V. Process feasibility and popularization prospect

[0053] 1. Simple process easy to implement

[0054] The preparation of the refining agent does not require complex equipment (only conventional equipment such as crucibles, crushers and ball mills), and the refining process has strong compatibility with existing magnesium electrolysis production lines, without the need for large-scale modification, and the enterprise is easy to put into production.

[0055] 2. Wide application range

[0056] It is suitable for all scenarios of electrolytic production of crude magnesium using the MgCl2-NaCl-CaCl2 system, and is especially suitable for magnesium reducing agent refining for sponge titanium, and has a wide popularization prospect.

[0057] In summary, the application has significant advantages in improving magnesium refining effect, reducing cost, ensuring safety and promoting industrial chain upgrading through component optimization, process improvement and system adaptation, and has important technical and economic value. BRIEF DESCRIPTION OF DRAWINGS

[0058] The accompanying drawings are used to provide a further understanding of the application, and constitute a part of the specification, and together with the embodiments of the application, make a further detailed explanation, but do not constitute a limitation on the application.

[0059] Figure 1 The flowchart of the preparation of the magnesium refining agent of the application. DETAILED DESCRIPTION

[0060] The technical solutions in the embodiments of the application will be described below in conjunction with the embodiments of the application. Obviously, the described embodiments are only a part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the application.

[0061] The chemical composition of the magnesium reducing agent refining agent in the application is:

[0062] MgCl2 30-40%, NaCl 40-45%, CaCl2 20-25% and CaF2 3-5%, and the balance is unavoidable impurities.

[0063] A clean crucible is prepared, and molten MgCl2 is added to the crucible, followed by adding 1 / 2 NaCl, and then adding the remaining 1 / 2 NaCl and CaCl2 alternately in multiple times. The temperature of the crucible is heated to 750-850°C until melting, and then CaF2 powder is added and stirred to obtain a mixed molten salt, so that the chemical composition of the mixed molten salt is: MgCl2 35-40%, NaCl 40-45%, CaCl2 20-25%, and CaF2 3-5%.

[0064] The purpose of adding the molten MgCl2 first is to help the NaCl added later to melt and form a eutectic. The purpose of adding the CaCl2 third is that solid CaCl2 added to the molten MgCl2 will produce a large amount of HCl smoke, which will cause the environment to deteriorate and harm the health of the workers.

[0065] The mixed molten salt is naturally cooled to room temperature, and then crushed to a block size of less than 100 mm. Then the refining agent block is crushed again in a jaw crusher or other equipment, and then transferred to a ball mill to be ground into particles with a diameter of less than 1.5 mm. Finally, the refining agent is packaged and sealed, and stored in a dry place. Here, the crushing and grinding of the refining agent must be carried out quickly in a dry environment to avoid hydrolysis of the refining agent due to moisture absorption.

[0066] Again, a furnace of the same proportion of refining agent is prepared, and after melting, the temperature is kept at 690-750°C.

[0067] The molten refining agent in the crucible is extracted using a ladle and added to a refining furnace or a crucible for refining, and the temperature is kept at 690-750°C. Then, the crude magnesium extracted from the electrolytic cell is added to the refining furnace or the crucible for refining. The refining agent powder is sprayed and covered on the surface of the crude magnesium. Argon gas is injected into the refining furnace or the crucible to protect the surface of the liquid magnesium from oxidation and burning. The refining time is 30-60 minutes.

[0068] To more clearly show the refining effect of the refining agent of the present application, Examples 1-4 are used for comparison and verification below. Example 1 is a crude magnesium sample without refining, and Examples 2-4 are refined magnesium samples after using the refining agent and refining method of the present application.

[0069] Example 1

[0070] The crude magnesium sample without refining is taken for component detection.

[0071] Component Mg Si Al Fe Mn Ni Content % 99.93 0.015 0.0333 0.017 0.0002 0.0015

[0072] Table 1

[0073] Example 2

[0074] The magnesium reducing agent is refined by the refining agent, and the refining agent comprises MgCl2 32%, NaCl 45%, CaCl2 20% and CaF2 3%.

[0075] Component Mg Si Al Fe Mn Ni Content % 99.96 0.0070 0.0111 0.0180 0.0003 0.0019

[0076] Table 2

[0077] The crude magnesium produced by electrolysis of magnesium chloride is refined by the magnesium reducing agent flux, and the impurity content of the magnesium after refining is shown in Table 2. As shown in Table 2, the magnesium reducing agent obtained by refining meets the requirements of 95A in the national standard GB / T3499-2011, and the quality of the magnesium is greatly improved.

[0078] Example 3

[0079] The magnesium reducing agent is refined by the refining agent, and the refining agent comprises MgCl2 35%, NaCl 42%, CaCl2 20% and CaF2 3%.

[0080] Component Mg Si Al Fe Mn Ni Content % 99.96 0.0070 0.0111 0.0170 0.0003 0.0021

[0081] Table 3

[0082] The crude magnesium produced by electrolysis of magnesium chloride is refined by the magnesium reducing agent flux, and the impurity content of the magnesium after refining is shown in Table 3. As shown in Table 3, the magnesium reducing agent obtained by refining meets the requirements of 95A in the national standard GB / T3499-2011, and the quality of the magnesium is greatly improved.

[0083] Example 4

[0084] The magnesium reducing agent is refined by the refining agent, and the refining agent comprises MgCl2 38%, NaCl 40%, CaCl2 20% and CaF2 2%.

[0085] Component Mg Si Al Fe Mn Ni Content % 99.96 0.0060 0.0117 0.0190 0.0003 0.0016

[0086] Table 4

[0087] The crude magnesium produced by electrolysis of magnesium chloride is refined by the magnesium reducing agent flux, and the impurity content of the magnesium after refining is shown in Table 4. As shown in Table 4, the magnesium reducing agent obtained by refining meets the requirements of 95A in the national standard GB / T3499-2011, and the quality of the magnesium is greatly improved.

[0088] Comparative Example 1 (refining agent of a quaternary molten salt system containing KCl)

[0089] The refining agent comprises MgCl2 30%, NaCl 30%, CaCl2 15%, KCl 20% and CaF2 5%, and the purity of each component is the same as the corresponding raw material standard of the application.

[0090] Preparation method: refer to the steps of claim 4 of the present application, mix and melt the ingredients in proportion (temperature 750-850℃), grind to a particle size of <1.5mm after cooling and crushing.

[0091] Refining process: same as example 2 of the present application (refining agent to crude magnesium weight ratio 4:3, temperature 700℃, argon protection, refining for 40min), and the crude magnesium is the raw material produced by the same electrolytic cell.

[0092] Refining magnesium component test results:

[0093] Component Mg Si Al Fe Mn Ni Content % 99.92 0.012 0.028 0.019 0.0003 0.0018

[0094] Comparative analysis: compared with example 2 of the present application (Mg purity 99.96%, Si 0.007%, Al 0.0111%), the comparative example introduces KCl, which leads to a decrease in the removal effect of impurities in magnesium (especially Al and Si), and the residual K element may enter the magnesium-chlorine cycle in the subsequent titanium sponge production, affecting the quality of titanium sponge. At the same time, the high cost of KCl increases the refining agent preparation cost by about 15%.

[0095] Comparative example 2 (using traditional ternary system but the ratio deviates from the range of the present application)

[0096] Refining agent composition (mass percentage): MgCl2 25%, NaCl 50%, CaCl2 20%, CaF2 5%, and the purity of each component meets the corresponding raw material standard of the present application.

[0097] Preparation method: same as the steps of claim 4 of the present application.

[0098] Refining process: same as example 3 of the present application (refining agent to crude magnesium weight ratio 5:3, temperature 720℃, argon protection, refining for 50min), and the crude magnesium is the raw material produced by the same electrolytic cell.

[0099] Refining magnesium component test results:

[0100] Component Mg Si Al Fe Mn Ni Content % Component Mg Si Fe Mn Ni Content % 99.90 0.014 0.031 0.021 0.0004 0.0020

[0101] Comparative analysis: the MgCl2 content in this comparative example is lower than the range of 30-45% defined in the present application, which leads to insufficient absorption of oxide impurities such as MgO, and the high proportion of NaCl increases the melting point of the molten salt system, reduces the fluidity, and reduces the impurity sedimentation efficiency. Compared with example 3 of the present application (Mg purity 99.96%, Si 0.007%, Al 0.0111%), the impurity removal rate is reduced by about 40%, and due to the poor fluidity of the molten salt, the refining time is extended to 50min, which still does not achieve the ideal effect, and does not meet the needs of industrialized and efficient production.

[0102] The application provides a new magnesium reducing agent flux, by suitable matching and improvement of the component content, the impurity removal capacity is improved, and the magnesium reducing agent is refined, so that the magnesium reducing agent meets the requirements of 95A in the national standard GB / T3499-2011, the quality of magnesium is greatly improved, a basis is provided for subsequent production of high-quality sponge titanium, and the application has important significance.

[0103] The application realizes multiple beneficial effects through optimization of the component design, preparation process and refining method of the magnesium refining agent, and specific analysis is as follows.

[0104] I. Solve the core technical problem and improve the refining effect

[0105] 1. Effectively remove key impurities

[0106] In view of the problem that MgO, SiO2, Al2O3 and other impurities are difficult to effectively remove during refining of crude magnesium in the prior art, by adjusting the component and ratio of the refining agent (MgCl2 30-45%, NaCl 35-45%, CaCl2 15-25%, CaF2 2-5%), the impurity removal capacity is significantly improved.

[0107] High content of MgCl2 enhances the absorption capacity of K, Na and other alkali metals and MgO, CaO and other oxide impurities;

[0108] Reasonable proportion of CaF2 increases the surface tension between the flux and molten magnesium, promoting the separation of non-metallic impurities (especially magnesium particles wrapped by magnesium oxide) and magnesium;

[0109] Optimized CaCl2 content improves the covering density, which can adsorb impurities in liquid magnesium from top to bottom to form sludge, further reducing the impurity content.

[0110] According to the verification of the embodiment, the purity of the refined magnesium is improved from 99.93% to 99.96%, the content of key impurities such as Si and Al is significantly reduced, and the requirements of 95A in the national standard GB / T3499-2011 are met.

[0111] 2. Adapt to the existing process system

[0112] In the prior art, enterprises change the original MgCl2-KCl-NaCl-CaCl2 quaternary molten salt system to MgCl2-NaCl-CaCl2 ternary system to reduce costs, but the traditional refining agent does not match the system, resulting in poor refining effect. The application directly uses the ternary molten salt system refining agent, which perfectly matches the electrolyte system of the existing magnesium electrolysis process, solves the technical contradiction of "non-matching of the molten salt system", and ensures stable and efficient refining process.

[0113] II. Reduce production cost and process risk

[0114] 1. Reduce raw material cost

[0115] Compared with the quaternary system containing KCl, the present application eliminates the high-priced KCl and uses cheap and readily available MgCl2, NaCl and CaCl2 as main components. All raw materials are conventional chemical products, which do not need special procurement, and greatly reduce the preparation cost of the refining agent.

[0116] 2. Reduce the risk of introducing impurities

[0117] The use of KCl in the quaternary system may cause the introduction of K and other impurities in the magnesium-chlorine cycle of titanium sponge production, affecting the quality of titanium sponge. The ternary system of the present application avoids the introduction of K element, reduces the risk of impurities in subsequent titanium sponge production from the source, and provides protection for the preparation of high-quality titanium sponge.

[0118] Three, optimize the preparation and refining process, and improve safety and operability

[0119] 1. Improve production environment and safety

[0120] In the preparation process, by designing the step of "first adding molten MgCl2, then adding NaCl and CaCl2 in batches", the problem of generating a large amount of HCl smoke when solid CaCl2 is directly added to high-temperature molten salt is avoided, reducing the pollution to the site environment and the health damage to the operators.

[0121] 2. Ensure the stability of the refining agent

[0122] The crushing and grinding process of the refining agent requires rapid operation in a dry environment to avoid hydrolysis, ensuring the chemical stability of the refining agent and ensuring its effective role in the refining process.

[0123] 3. Strong controllability of the refining process

[0124] During refining, the dual-acting mode of "adding molten refining agent at the bottom + spraying powder refining agent on the surface" is used, combined with argon protection and precise temperature control at 690-750℃, which prevents liquid magnesium from oxidizing and burning, and improves the impurity removal efficiency through the synergistic effect of flux refining and gravity settling. The refining time only needs 30-60 minutes, which is suitable for industrialized continuous production.

[0125] Four, promote the quality upgrading of the industrial chain

[0126] The present application improves the purity of the magnesium reducing agent, providing high-quality raw materials for downstream titanium sponge production. Since the impurity content of titanium sponge directly affects the mechanical properties of titanium and titanium alloys, the application of the present application can indirectly improve the quality of titanium used in high-end fields such as aerospace, deep-sea titanium materials and biological materials, which has significant industrial value.

[0127] V. Process feasibility and promotion prospects

[0128] 1. Simple process easy to implement

[0129] The preparation of the refining agent does not require complex equipment (only conventional equipment such as crucibles, crushers, ball mills, etc.), the refining process has strong compatibility with existing magnesium electrolysis production lines, does not require large-scale modification, and is easy for enterprises to put into production.

[0130] 2. Wide application range

[0131] It is suitable for all scenarios of electrolytic production of crude magnesium using the MgCl2-NaCl-CaCl2 system, and is especially suitable for magnesium reducing agent refining matched with sponge titanium, and has wide promotion prospects.

[0132] In summary, the present application has significant advantages in improving magnesium refining effect, reducing cost, ensuring safety, and promoting industrial chain upgrading through component optimization, process improvement, and system adaptation, and has important technical and economic value.

[0133] The above shows and describes the basic principles, main features and advantages of the present application. It should be understood by those skilled in the art that the present application is not limited by the above examples, and the above examples and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A magnesium refining agent characterized by: The composition comprises the following ingredients with the following mass percentage contents: MgCl2 composition 30-45%, NaCl composition 35-45%, CaCl2 composition 15-25%, and CaF2 composition 2-5%, the sum of the mass percentage contents of the ingredients being 100%; wherein the MgCl2 composition contains MgCl2≥98.0%, MgO≤0.5%, Fe≤0.01%, and Ti≤0.008%; the NaCl composition contains NaCl≥99.1%, SO4 2- ≤0.3%, moisture≤0.05%, and water-insoluble substances≤0.05%; the CaCl2 composition contains CaCl2≥95.0%, SO4 2- ≤0.01%, moisture≤0.05%, and water-insoluble substances≤0.3%; and the CaF2 composition contains CaF2≥98.0%, CO3 2- ≤0.3%, SO4 2- ≤0.5%, Si≤0.53%, Fe≤0.07%, and H2O≤0.05%.

2. The magnesium refining agent according to claim 1, characterized in that: The magnesium refining agent is composed of the following ingredients with mass percentage: MgCl2 32-40%, NaCl 40-45%, CaCl2 20-25% and CaF2 3-5%.

3. The magnesium refining agent according to claim 1, characterized in that: The magnesium refining agent is composed of the following ingredients with mass percentage: MgCl2 32-40%, NaCl 40-45%, CaCl2 20-25% and CaF2 3-5%.

4. A process for the production of a magnesium refining agent as claimed in any one of claims 1 to 3, characterized in that The method comprises the following steps: a. According to the mass percentage of the magnesium refining agent in claim 1, the crucible is heated to 600℃ and kept for 4 hours, then the molten MgCl2 is added, then 1 / 2 amount of NaCl is added, and the remaining 1 / 2 amount of NaCl and CaCl2 are alternately added into the crucible for multiple times, the temperature of the crucible is heated to 750-850℃ until the material is completely melted, then CaF2 powder is added and stirred to obtain a mixed molten salt; b. The mixed molten salt obtained in step a is naturally cooled to room temperature, crushed to a block size of less than 100mm, then transferred to a jaw crusher for crushing, and finally ground into particles with a diameter of less than 1.5mm in a ball mill, and finally packaged, sealed and stored in a dry place.

5. The method of preparing a magnesium refining agent according to claim 4, characterized in that: The crushing and grinding process in step b is carried out quickly in a dry environment.

6. A method of refining magnesium, characterized by, The method comprises the following steps: S1. The magnesium refining agent in a molten state prepared in step a of claim 4 is added into a refining furnace or a crucible and kept at 690-750℃; S2. The crude magnesium extracted from the electrolytic cell is added into the refining furnace or the crucible in step S1; S3. The magnesium refining agent prepared in step b of claim 4 is sprayed and covered on the surface of the crude magnesium, argon gas is filled for protection, and refining is carried out for 30-60min; The weight ratio of the magnesium refining agent to the crude magnesium is 4-5:3, and the crude magnesium is obtained by electrolysis using the MgCl2-NaCl-CaCl2 molten salt system electrolyte.

7. The method of refining magnesium according to claim 6, characterized in that: The argon gas is used as the spraying gas for spraying the magnesium refining agent in step S3.

8. The method of refining magnesium according to claim 6, characterized in that: The spraying amount of the magnesium refining agent in step S3 is 0.6-1.0kg per ton of crude magnesium.

9. The method of refining magnesium according to claim 6, characterized by: The refining is carried out in a combination of the flux refining method and the settling refining method.

10. The method of refining magnesium according to claim 6, characterized in that: The refining is continuous refining.

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