Process for treating a magnesium chloride melt, a magnesium chloride melting furnace and a method for the electrolytic production of metallic magnesium

Abstract

This invention relates to the field of electrolytic magnesium technology, and discloses a molten chlorination furnace and method for treating magnesium chloride, as well as a method for electrolytically preparing magnesium. The molten chlorination furnace includes: a furnace shell and a molten chlorination chamber, a clarification chamber, and a chlorination purification chamber disposed within the furnace shell; wherein, the bottom of the molten chlorination chamber is provided with a raw material and reducing agent inlet and a chlorinating agent inlet, and the top is provided with a flue gas outlet; the clarification chamber is separated from the molten chlorination chamber by a first wall, on which, from top to bottom, are provided a first flue gas hole, a first liquid flow hole, and a slag flow hole, with the slag flow hole located at the lowest point of the bottom wall of the clarification chamber; the clarification chamber and the chlorination purification chamber are separated by a second wall, on which, from top to bottom, are provided a second flue gas hole and a second liquid flow hole; the top of the chlorination purification chamber is provided with a liquid extraction hole and a movable chlorinating agent spray gun, and the bottom of the side wall of the chlorination purification chamber is provided with a slag discharge port. This invention can effectively remove MgO and is applicable to the treatment of hydrous magnesium chloride.

Description

Technical Field

[0001] This invention relates to the field of electrolytic magnesium technology, specifically to a molten chlorination furnace and method for processing magnesium chloride, and a method for electrolytically preparing metallic magnesium. Background Technology

[0002] Currently, the industrial production of metallic magnesium typically employs molten salt electrolysis. Molten magnesium chloride is added to an electrolytic cell and electrolysis is carried out under direct current. Liquid magnesium is generated at the cathode, and chlorine gas is generated at the anode. Because the density of liquid magnesium is lower than that of molten salt, it rises with the electrolyte circulation and accumulates on the electrolyte surface. It is periodically extracted and transported to downstream refining and casting processes to produce commercial metallic magnesium. Chlorine gas rises to the surface of the electrolyte at the anode and is extracted from the electrolytic cell by a chlorine blower (compressor).

[0003] The raw materials for molten salt electrolysis can include anhydrous magnesium chloride, magnesium chloride-containing chlorides, and hydrated magnesium chloride. All of these raw materials contain MgO impurities. Since MgO is a solid phase, it exists as a suspended inclusion in the molten magnesium chloride, making it difficult to remove completely through clarification alone. Furthermore, due to the high temperature of the molten pool and the constant thermal convection, MgO in the clarified magnesium chloride solution cannot be completely removed if MgO sludge is present at the bottom of the molten pool. This is because the MgO sludge at the bottom continuously migrates into the clarified solution, which is the main reason why the MgO content cannot be reduced in industrial magnesium chloride dehydration tests. In addition,

[0004] Currently, existing equipment for processing molten magnesium chloride is only suitable for anhydrous magnesium chloride. It cannot simultaneously dehydrate the magnesium chloride during the melting process, making it unsuitable for molten magnesium chloride. Furthermore, due to the high MgO content in anhydrous magnesium chloride, typically above 0.5%, complete MgO removal is impossible, and the utilization of MgO slag is insufficient. The MgO slag layer formed after MgO precipitation in the magnesium chloride melt contains only 15-25% MgO, with the remainder being anhydrous magnesium chloride. Therefore, direct discharge of MgO slag also leads to the loss of MgCl2, resulting in significant Mg loss and consequently increasing the production cost of metallic magnesium. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of existing technologies, such as the inability to melt and process hydrated magnesium chloride and the inability to effectively remove MgO. This invention provides a molten chlorination furnace and method for processing magnesium chloride, as well as a method for electrolytically preparing metallic magnesium. The molten chlorination furnace is equipped with a melting chlorination chamber, a clarification chamber, and a chlorination purification chamber. Through the through-holes between the chambers, liquid overflow, solid particle flow, and gas flow are achieved, thus effectively removing MgO. This invention is applicable to the processing of hydrated magnesium chloride.

[0006] To achieve the above objectives, in a first aspect, the present invention provides a molten chlorination furnace for processing magnesium chloride, comprising: a furnace shell and a molten chlorination chamber, a clarification chamber and a chlorination purification chamber disposed in the furnace shell;

[0007] The melting chlorination chamber has a raw material and reducing agent inlet and a chlorinating agent inlet at the bottom, and a flue gas outlet at the top. The clarification chamber and the melting chlorination chamber are separated by a first wall. On the first wall, a first flue gas hole, a first liquid flow hole and a slag flow hole are provided from top to bottom. The slag flow hole is located at the lowest point of the bottom wall of the clarification chamber. The clarification chamber and the melting chlorination chamber are connected through the first flue gas hole, the first liquid flow hole and the slag flow hole.

[0008] The clarification chamber and the chlorination purification chamber are separated by a second wall. On the second wall, a second flue gas hole and a second liquid flow hole are provided from top to bottom, which connect the clarification chamber and the chlorination purification chamber. The top of the chlorination purification chamber is provided with a liquid extraction hole and a movable chlorinating agent spray gun, and the bottom of the side wall of the chlorination purification chamber is provided with a slag discharge port.

[0009] Heating electrodes are installed in the melting chlorination chamber, clarification chamber, and chlorination purification chamber.

[0010] Preferably, the bottom of the melting chlorination chamber has an inverted conical structure, and preferably, the taper of the bottom of the melting chlorination chamber is 5°-18°.

[0011] Preferably, a powder spray gun is installed at the inlet of the raw materials and reducing agent.

[0012] Preferably, the powder spray gun forms an angle with the bottom wall of the melting chlorination chamber.

[0013] Preferably, a chlorinating agent spray gun is installed at the chlorinating agent inlet.

[0014] Preferably, the chlorinating agent spray gun forms an angle with the bottom wall of the melting chlorination chamber.

[0015] Preferably, the bottom of the melting chlorination chamber is lower than the bottom of the clarification chamber; the bottom wall of the clarification chamber is sloping, gradually decreasing in the direction from the second wall to the first wall, and the lowest point of the bottom wall of the clarification chamber is connected to the slag flow hole.

[0016] Preferably, the slope of the bottom wall of the clarification chamber is 7°-12°.

[0017] Preferably, the slag discharge holes are inclined and gradually decrease in the direction from the second wall to the first wall.

[0018] Preferably, the slope of the slag discharge hole is the same as the slope of the bottom wall of the clarification chamber.

[0019] Preferably, the bottom wall of the chlorination purification chamber is sloping, gradually decreasing in the direction from the first wall to the second wall, and the lowest point of the bottom wall of the chlorination purification chamber is connected to the slag discharge port.

[0020] Preferably, the slope of the bottom wall of the chlorination purification chamber is 10°-20°.

[0021] Preferably, the top of the chlorination purification chamber is provided with a through hole, and a movable chlorinating agent spray gun is installed in the through hole. The movable chlorinating agent spray gun moves in the vertical direction and is connected to a lifting device.

[0022] Preferably, there are at least two heating electrodes in each chamber, and the length of the heating electrode immersed in molten magnesium chloride is 1 / 3 to 2 / 3 of the length of the heating electrode.

[0023] Secondly, the present invention provides a method for processing magnesium chloride, the method being carried out in the molten chlorination furnace for processing magnesium chloride described above, and the method comprising the following steps:

[0024] The magnesium chloride to be treated is mixed with a reducing agent to obtain a gas-solid mixture for injection. The gas-solid mixture is then introduced into the melting chlorination chamber, and the chlorinating agent is introduced into the melting chlorination chamber. The heating electrode is turned on, so that the magnesium oxide in the magnesium chloride to be treated is converted into magnesium chloride in the melting chlorination chamber.

[0025] The liquid in the melting chlorination chamber flows into the clarification chamber and the chlorination purification chamber sequentially through the first liquid flow hole and the second liquid flow hole by gravity, so that the outlet of the movable chlorinating agent spray gun is immersed in the liquid in the chlorination purification chamber, and chlorinating agent is introduced into the movable chlorinating agent spray gun.

[0026] Electrolytic magnesium raw material was extracted from the extraction hole.

[0027] Preferably, the magnesium chloride to be treated is hydrated magnesium chloride. Preferably, the amount of water of crystallization bound to each mole of magnesium chloride in the magnesium chloride to be treated is less than or equal to 1 mole.

[0028] Preferably, the reducing agent is at least one selected from coke powder, methane, and carbon monoxide;

[0029] Preferably, the chlorinating agent is hydrogen chloride or chlorine gas. Preferably, the chlorinating agent is anhydrous hydrogen chloride gas.

[0030] Preferably, the molar ratio of magnesium chloride to reducing agent is 1:(0.01-0.1).

[0031] Preferably, the molar ratio of magnesium chloride to be treated to chlorinating agent entering the melting chlorination chamber is 1:(0.03-0.15).

[0032] Preferably, the molar ratio of magnesium chloride to be treated to chlorinating agent entering the chlorination purification chamber is 1:(0.01-0.1).

[0033] Preferably, the method further includes: adjusting the immersion depth of the heating electrode according to the temperature of the molten pool in each chamber and / or the power of the heating electrode;

[0034] The insertion depth of the movable chlorinating agent spray gun is determined based on the MgO content in the anhydrous magnesium chloride solution in the chlorination purification chamber. The higher the MgO content in the anhydrous magnesium chloride solution in the chlorination purification chamber, the deeper the insertion depth of the movable chlorinating agent spray gun.

[0035] Thirdly, the present invention provides a method for preparing metallic magnesium by electrolysis, including the method for treating magnesium chloride described above.

[0036] The technical solution of the present invention has at least the following beneficial effects:

[0037] 1. The furnace shell is equipped with a sequentially connected melting chlorination chamber, a clarification chamber, and a chlorination purification chamber. Magnesium chloride raw material (which can be hydrated or anhydrous magnesium chloride), reducing agent, and chlorinating agent enter the melting chlorination chamber through the raw material and reducing agent inlet and the chlorinating agent inlet. Under the action of heating electrodes, they form a molten liquid. After completing the dehydration, hydrolysis, MgO chlorination, and chlorine acidification processes of hydrated magnesium chloride in the melting chlorination chamber, the molten liquid enters the clarification chamber through the first liquid flow hole. Magnesium oxide mixed in the magnesium chloride melt undergoes a static settling process and settles at the bottom of the clarification chamber. The magnesium oxide flows back to the melting chlorination chamber from the slag flow hole. The magnesium chloride melt that has completed the settling process enters the chlorination purification chamber through the second liquid flow hole. Chlorinating agent is introduced into the movable chlorinating agent spray gun to further chlorinate and purify the residual MgO in the magnesium chloride melt. Therefore, this molten chlorination furnace, by setting up a melting chlorination chamber, a clarification chamber, and a chlorination purification chamber, and by using the through holes between the chambers to achieve the overflow of liquid, the flow of solid particles, and the flow of gas, can effectively remove MgO and is applicable to the treatment of hydrous magnesium chloride.

[0038] 2. This invention enables the molten chlorination and dehydration of hydrated magnesium chloride, and is also applicable to anhydrous magnesium chloride feedstocks, thus expanding the range of magnesium chloride feedstocks. This invention fully chlorinates MgO sludge, improving magnesium recovery rate, and thoroughly removes residual MgO impurities from the anhydrous magnesium chloride melt through deep chlorination clarification, reducing their impact on the magnesium electrolysis process. Furthermore, this invention improves the utilization rate of the chlorination medium and increases chlorination efficiency. Compared to traditional magnesium chloride dehydration processes, it shortens the magnesium chloride dehydration process, achieving rapid dehydration and reducing the production cost of metallic magnesium. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the molten chlorination furnace for processing magnesium chloride provided in an embodiment of the present invention;

[0040] Figure 2 This is a schematic diagram of the AA cross-sectional structure of the molten chlorination furnace for processing magnesium chloride provided in an embodiment of the present invention.

[0041] The attached figures are labeled as follows:

[0042] 1. Melting chlorination chamber; 2. Clarification chamber; 3. Chlorination purification chamber; 4. First wall; 5. Second wall; 6. Heating electrodes;

[0043] 101. Raw material and reducing agent inlet; 102. Chlorinating agent inlet; 103. Bottom of melting chlorination chamber; 104. Flue gas outlet; 201. Bottom wall of clarification chamber; 301. Liquid extraction hole; 302. Movable chlorinating agent spray gun; 303. Slag discharge port; 304. Bottom wall of chlorination purification chamber; 401. First flue gas port; 402. First liquid flow port; 403. Slag discharge port; 501. Second flue gas port; 502. Second liquid flow port. Detailed Implementation

[0044] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0045] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0046] For example, when a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range. In this specification and claims, range definitions may be combined and / or interchanged, unless otherwise stated, these ranges include all sub-ranges contained therein.

[0047] In a first aspect, the present invention provides a molten chlorination furnace for processing magnesium chloride, comprising: a furnace shell and a molten chlorination chamber 1, a clarification chamber 2, and a chlorination purification chamber 3 disposed in the furnace shell; wherein, the bottom 103 of the molten chlorination chamber is provided with a raw material and reducing agent inlet 101 and a chlorinating agent inlet 102, and the top of the molten chlorination chamber is provided with a flue gas outlet 104; the clarification chamber 2 is separated from the molten chlorination chamber 1 by a first wall 4, and a first flue gas hole 401, a first liquid flow hole 402, and a slag flow hole 403 are provided from top to bottom on the first wall 4, and the slag flow hole 403 is located at the lowest point of the bottom wall of the clarification chamber, and the clarification chamber and the molten chlorination chamber are connected through the first flue gas hole 401, the first liquid flow hole 402, and the slag flow hole 403. The clarification chamber 2 and the chlorination purification chamber 3 are separated by a second wall 5. A second flue gas hole 501 and a second liquid flow hole 502 are provided on the second wall 5 from top to bottom, and the clarification chamber 2 and the chlorination purification chamber 3 are connected through the second flue gas hole 501 and the second liquid flow hole 502. A liquid extraction hole 301 and a movable chlorinating agent spray gun 302 are provided at the top of the chlorination purification chamber, and a slag discharge port 303 is provided at the bottom of the side wall of the chlorination purification chamber. Heating electrodes 6 are provided in the melting chlorination chamber 1, the clarification chamber 2 and the chlorination purification chamber 3.

[0048] The following example, using dried magnesium chloride as raw material, illustrates the technical solution of this invention. Magnesium chloride hexahydrate, after being air-dried, is mixed with a reducing agent, such as coke powder, methane, or carbon monoxide. This mixture is then sprayed into the melting chlorination chamber through a powder spray gun from the raw material and reducing agent inlet 101. Chlorine gas is sprayed into the melting chlorination chamber through a spray gun from the chlorinating agent inlet 102. Within the melting chlorination chamber, complex processes such as dehydration and hydrolysis of hydrated magnesium chloride, MgO chlorination, and chlorine acidification simultaneously occur in the molten magnesium chloride pool. The main reaction equations are as follows. In the melting purification chamber, the MgO in the melt is chlorinated by chlorine gas and the reducing agent, and gaseous water is mainly discharged from this chamber outside the furnace.

[0049] MgCl2·xH2O = MgCl2 + xH2O(g)

[0050] MgCl₂ + H₂O = MgO + 2HCl(g)

[0051] MgO + Cl2(g) + C = MgCl2 + CO(g)

[0052] MgO + Cl2(g) + CO(g) = MgCl2 + CO2(g)

[0053] Cl2(g) + H2O(g) + C = 2HCl(g) + CO(g)

[0054] Cl2(g) + H2O(g) + CO = 2HCl(g) + CO2(g)

[0055] The anhydrous magnesium chloride melt obtained after melting and chlorination flows into the clarification chamber through the first liquid flow hole 402. In the clarification chamber, the magnesium oxide mixed in the anhydrous magnesium chloride melt undergoes a static settling process and settles at the bottom of the clarification chamber. It then flows from the bottom into the melting and chlorination chamber to continue participating in the chlorination reaction, thus realizing the reuse of MgO slag.

[0056] After clarification in the clarification chamber, the anhydrous magnesium chloride solution flows into the chlorination purification chamber through the second liquid flow hole 502. In this chamber, the residual MgO in the magnesium chloride melt is further purified by deep chlorination using a movable chlorinating agent spray gun 302. The resulting gas is HCl or Cl2+CO. Finally, the MgO content in the anhydrous magnesium chloride melt is completely removed after deep chlorination purification, and it is then extracted through the extraction hole 301 for use as a raw material for electrolytic magnesium metal.

[0057] In some embodiments, the bottom 103 of the melting chlorination chamber has an inverted conical structure. In a preferred embodiment, the taper of the bottom 103 of the melting chlorination chamber is 5°-18°. The inverted conical structure of the bottom of the melting chlorination chamber facilitates the collection of magnesium oxide slag.

[0058] In some embodiments, a powder spray gun is installed at the raw material and reducing agent inlet 101. The powder spray gun forms an angle with the bottom wall of the melting chlorination chamber. A chlorinating agent spray gun is installed at the chlorinating agent inlet 102. The chlorinating agent spray gun also forms an angle with the bottom wall of the melting chlorination chamber. Inserting the powder spray gun and chlorinating agent spray gun into the melting chlorination chamber using a side-insertion method is beneficial for increasing the melting rate of the powder in the molten pool, accelerating the reaction with the chlorinating agent, and reducing powder dust loss.

[0059] In some embodiments, the bottom 103 of the melting chlorination chamber is lower than the bottom of the clarification chamber; the bottom wall 201 of the clarification chamber is sloping, gradually decreasing in the direction from the second wall 5 to the first wall 4, and the lowest point of the bottom wall of the clarification chamber communicates with the slag discharge hole 403. Preferably, the slope of the bottom wall 201 of the clarification chamber is 7°-12°. Further, in some embodiments, the slag discharge hole 403 is inclined, gradually decreasing in the direction from the second wall 5 to the first wall 4. Preferably, the slope of the slag discharge hole 403 is the same as the slope of the bottom wall 201 of the clarification chamber. Thus, the magnesium oxide slag settled at the bottom of the clarification chamber can flow into the melting chlorination chamber by gravity, relying on the inclined angle of the bottom of the clarification chamber.

[0060] In some embodiments, the bottom wall 304 of the chlorination purification chamber is sloped, gradually decreasing in slope from the first wall 4 to the second wall 5, with the lowest point of the bottom wall communicating with the slag discharge port 303. Preferably, the slope of the bottom wall 304 of the chlorination purification chamber is 10°-20°. Thus, the residual magnesium oxide slag in the chlorination purification chamber can be discharged from the slag discharge port 303 of the chlorination purification chamber under its own gravity, relying on the inclination angle of the bottom wall 304.

[0061] In some embodiments, a through hole is provided at the top of the chlorination purification chamber, and a movable chlorinating agent spray gun 302 is disposed in the through hole. The movable chlorinating agent spray gun 302 moves in a vertical direction and is connected to a lifting device. In this document, the lifting device can adopt a conventional configuration found in the prior art; this invention does not specifically limit its use, as long as the movable chlorinating agent spray gun 302 can move vertically under the action of the lifting device. In this document, "vertical direction" refers to... Figures 1-2 The schematic diagram shows directions pointing from the top to the bottom of the chlorination purification chamber or from the bottom to the top. Thus, the chlorination purification chamber can further perform deep chlorination using a chlorinating agent. By flexibly adjusting the movable chlorinating agent spray gun 302, deep chlorination of the clarified solution can be achieved when the gun is inserted, followed by a settling and re-clarification process after the gun is removed, thereby completely removing MgO and other impurities.

[0062] In some embodiments, the number of heating electrodes 6 in each chamber is at least two, and the length of the heating electrodes 6 immersed in molten magnesium chloride is 1 / 3 to 2 / 3 of the length of the heating electrodes 6.

[0063] Secondly, the present invention provides a method for processing magnesium chloride, the method being carried out in the molten chlorination furnace for processing magnesium chloride described above, and the method comprising the following steps:

[0064] (1) Mix the magnesium chloride to be treated with the reducing agent to obtain a gas-solid mixture for spraying. Let the gas-solid mixture for spraying enter the melting chlorination chamber, let the chlorinating agent enter the melting chlorination chamber, turn on the heating electrode 6, and let the magnesium oxide in the magnesium chloride to be treated be converted into magnesium chloride in the melting chlorination chamber.

[0065] (2) The liquid in the melting chlorination chamber enters the clarification chamber and the chlorination purification chamber in sequence through the first liquid flow hole 402 and the second liquid flow hole 502 by gravity flow, so that the outlet of the movable chlorinating agent spray gun 302 is immersed in the liquid in the chlorination purification chamber, and chlorinating agent is introduced into the movable chlorinating agent spray gun 302.

[0066] (3) Electrolytic magnesium raw material was extracted from the extraction hole 301.

[0067] The method provided by this invention involves introducing magnesium chloride to be treated, a reducing agent, and a chlorinating agent into a melting chlorination chamber. Under the action of the heating electrode 6, a molten liquid is formed. After the molten liquid completes processes such as dehydration, hydrolysis, MgO chlorination, and chlorine acidification of the hydrated magnesium chloride in the melting chlorination chamber, it enters the clarification chamber through the first liquid flow hole 402. The magnesium oxide mixed in the magnesium chloride melt undergoes a static settling process and settles at the bottom of the clarification chamber. The magnesium oxide flows back into the melting chlorination chamber through the slag flow hole 403. The magnesium chloride melt that has completed the settling process enters the chlorination purification chamber through the second liquid flow hole 502. The chlorinating agent is introduced into the movable chlorinating agent spray gun 302 to further chlorinate and purify the residual MgO in the magnesium chloride melt.

[0068] In some embodiments, the magnesium chloride to be treated is hydrated magnesium chloride. Preferably, the amount of water of crystallization bound to each mole of magnesium chloride in the magnesium chloride to be treated is less than or equal to 1 mole. This invention enables the molten chlorination and dehydration of hydrated magnesium chloride, and is also applicable to anhydrous magnesium chloride raw materials, thereby expanding the range of magnesium chloride raw materials.

[0069] In some embodiments, the reducing agent is at least one of coke powder, methane, and carbon monoxide. The reducing agent reacts with the magnesium chloride to be treated in a melting chlorination chamber, undergoing complex processes such as dehydration and hydrolysis of the hydrated magnesium chloride, MgO chlorination, and chlorine acidification. Simultaneously, the magnesium oxide is chlorinated while the hydrated magnesium chloride is being dehydrated.

[0070] In some embodiments, the chlorinating agent is anhydrous hydrogen chloride gas or chlorine gas. Preferably, the chlorinating agent is anhydrous hydrogen chloride gas.

[0071] In some embodiments, the molar ratio of magnesium chloride to reducing agent is 1:(0.01-0.1).

[0072] In some embodiments, the molar ratio of magnesium chloride to be treated to chlorinating agent entering the melting chlorination chamber is 1:(0.03-0.15).

[0073] In some embodiments, the molar ratio of magnesium chloride to be treated to chlorinating agent entering the chlorination purification chamber is 1:(0.01-0.1).

[0074] When the ratio of raw materials is within the appropriate range mentioned above, it is beneficial to achieve the dehydration of hydrated magnesium chloride, the chlorination of magnesium oxide, and subsequent deep chlorination.

[0075] In some feasible implementations, the method further includes adjusting the immersion depth of the heating electrode 6 according to the temperature of the molten pool in each chamber and / or the power of the heating electrode 6, so that the temperature of the solution in each chamber is maintained within a suitable range.

[0076] In some feasible implementations, the insertion depth of the movable chlorinating agent spray gun 302 is determined based on the MgO content in the anhydrous magnesium chloride solution within the chlorination purification chamber 3. Specifically, the higher the MgO content in the anhydrous magnesium chloride solution within the chlorination purification chamber 3, the deeper the insertion depth of the movable chlorinating agent spray gun 302. This facilitates the effective removal of magnesium oxide and other impurities.

[0077] In some feasible implementations, after introducing the chlorinating agent using the movable chlorinating agent spray gun 302, the solution can be allowed to stand and clarify. Thus, by flexibly adjusting the movable chlorinating agent spray gun 302, deep chlorination of the clarified solution can be achieved when the gun is inserted, followed by a process of standing and clarifying the purified solution after the gun is removed. This further facilitates the effective and deep removal of magnesium oxide and other impurities.

[0078] Thirdly, the present invention provides a method for preparing metallic magnesium by electrolysis, including the method for treating magnesium chloride described above.

[0079] The technical solution of the present invention will be further illustrated below through embodiments. These embodiments are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0080] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0081] Example 1

[0082] This embodiment provides a molten chlorination furnace for processing magnesium chloride. Please refer to [link to relevant documentation]. Figure 1 ,

[0083] The molten chlorination furnace includes: a furnace shell and a molten chlorination chamber 1, a clarification chamber 2, and a chlorination purification chamber 3 disposed within the furnace shell;

[0084] The bottom 103 of the melting chlorination chamber is provided with a raw material and reducing agent inlet 101 and a chlorinating agent inlet 102, and the top of the melting chlorination chamber is provided with a flue gas outlet 104. The clarification chamber 2 and the melting chlorination chamber 1 are separated by a first wall 4. On the first wall 4, a first flue gas hole 401, a first liquid flow hole 402 and a slag flow hole 403 are provided from top to bottom, and the slag flow hole 403 is located at the lowest point of the bottom wall of the clarification chamber. The clarification chamber 2 and the melting chlorination chamber 1 are connected through the first flue gas hole 401, the first liquid flow hole 402 and the slag flow hole 403.

[0085] The clarification chamber 2 and the chlorination purification chamber 3 are separated by a second wall 5. On the second wall 5, a second flue gas hole 501 and a second liquid flow hole 502 are provided from top to bottom, and the clarification chamber 2 and the chlorination purification chamber 3 are connected through the second flue gas hole 501 and the second liquid flow hole 502. The top of the chlorination purification chamber is provided with a liquid extraction hole 301 and a movable chlorinating agent spray gun 302, and the bottom of the side wall of the chlorination purification chamber 3 is provided with a slag discharge port 303.

[0086] Heating electrodes 6 are installed in the melting chlorination chamber 1, the clarification chamber 2, and the chlorination purification chamber 3.

[0087] The bottom 103 of the melting chlorination chamber has an inverted conical structure with a taper of 12°. The bottom 103 of the melting chlorination chamber is lower than the bottom of the clarification chamber. The bottom wall 201 of the clarification chamber is sloped, gradually decreasing in elevation along the direction from the second wall 5 to the first wall 4, and its lowest point communicates with the slag discharge hole 403. The slope of the bottom wall 201 of the clarification chamber is 10°. The slag discharge hole 403 is inclined, gradually decreasing in elevation along the direction from the second wall 5 to the first wall 4, and its slope is the same as that of the bottom wall 201 of the clarification chamber. The bottom wall 304 of the chlorination purification chamber is sloped, gradually decreasing in elevation along the direction from the first wall 4 to the second wall 5, and its lowest point communicates with the slag discharge port 303. The slope of the bottom wall 304 of the chlorination purification chamber is 15°.

[0088] A powder spray gun is installed at the raw material and reducing agent inlet 101, forming an angle with the bottom wall of the melting chlorination chamber. A chlorinating agent spray gun is installed at the chlorinating agent inlet 102, also forming an angle with the bottom wall of the melting chlorination chamber.

[0089] The top of the chlorination purification chamber is provided with a through hole, and a movable chlorinating agent spray gun 302 is installed in the through hole. The movable chlorinating agent spray gun 302 is connected to a lifting device and can move in the vertical direction.

[0090] There are two heating electrodes 6 in each chamber, and the length of the heating electrode 6 immersed in molten magnesium chloride is 1 / 3 of the length of the heating electrode.

[0091] Example 2

[0092] This embodiment provides a method for processing magnesium chloride, which is carried out in the molten chlorination furnace for processing magnesium chloride in Example 1. The method includes the following steps:

[0093] (1) The magnesium chloride to be treated is mixed with a reducing agent to obtain a gas-solid mixture for injection. The gas-solid mixture is then introduced into the melting chlorination chamber 1, and the chlorinating agent is introduced into the melting chlorination chamber 1. The heating electrode 6 is turned on, so that the magnesium oxide in the magnesium chloride to be treated is converted into magnesium chloride in the melting chlorination chamber 1. The magnesium chloride to be treated is hydrated magnesium chloride, and the amount of water of crystallization bound to each mole of magnesium chloride in the hydrated magnesium chloride is 0.5 moles. The reducing agent is coke powder, and the molar ratio of magnesium chloride to reducing agent is 1:0.03. The chlorinating agent is chlorine gas, and the molar ratio of magnesium chloride to chlorinating agent entering the melting chlorination chamber is 1:0.04.

[0094] (2) The liquid in the melting chlorination chamber enters the clarification chamber and the chlorination purification chamber in sequence through the first liquid flow hole 402 and the second liquid flow hole 502 by gravity flow, so that the outlet of the movable chlorinating agent spray gun 302 is immersed in the liquid in the chlorination purification chamber, and chlorinating agent is introduced into the movable chlorinating agent spray gun 302; the molar ratio of magnesium chloride to be treated to the chlorinating agent entering the chlorination purification chamber is 1:0.04.

[0095] (3) Electrolytic magnesium raw material was extracted from the extraction hole.

[0096] In this embodiment, the MgO content in the magnesium chloride raw material to be treated is 1%.

[0097] The MgO impurity content in the electrolytic magnesium raw material (i.e. anhydrous magnesium chloride melt) obtained by step (3) of this embodiment is 0.2%, the MgO chlorination rate is 80%, and the MgCl2 loss rate is 8%.

[0098] Example 3

[0099] This embodiment provides a method for processing magnesium chloride, which is carried out in the molten chlorination furnace for processing magnesium chloride in Example 1. The method includes the following steps:

[0100] (1) The magnesium chloride to be treated is mixed with a reducing agent to obtain a gas-solid mixture for injection. The gas-solid mixture is then introduced into the melting chlorination chamber 1, and the chlorinating agent is introduced into the melting chlorination chamber 1. The heating electrode is turned on, so that the magnesium oxide in the magnesium chloride to be treated is converted into magnesium chloride in the melting chlorination chamber 1. The magnesium chloride to be treated is hydrated magnesium chloride, and the amount of water of crystallization bound to each mole of magnesium chloride in the hydrated magnesium chloride is 0.8 moles. The reducing agent is carbon monoxide, and the molar ratio of the magnesium chloride to the reducing agent is 1:0.05. The chlorinating agent is chlorine gas, and the molar ratio of the magnesium chloride to the chlorinating agent entering the melting chlorination chamber is 1:0.06.

[0101] (2) The liquid in the melting chlorination chamber enters the clarification chamber and the chlorination purification chamber in sequence through the first liquid flow hole 402 and the second liquid flow hole 502 by gravity flow, so that the outlet of the movable chlorinating agent spray gun 302 is immersed in the liquid in the chlorination purification chamber, and chlorinating agent is introduced into the movable chlorinating agent spray gun 302; the molar ratio of magnesium chloride to be treated to the chlorinating agent entering the chlorination purification chamber is 1:0.08.

[0102] After 1 hour of purging, lift the movable chlorinating agent spray gun to move the liquid out of the chlorination purification chamber from the outlet of the movable chlorinating agent spray gun, and then let it stand for 0.5 hours.

[0103] (3) Electrolytic magnesium raw material was extracted from the extraction hole.

[0104] In this embodiment, the MgO content in the magnesium chloride raw material to be treated is 1%.

[0105] The MgO impurity content in the electrolytic magnesium raw material (i.e., anhydrous magnesium chloride melt) obtained in step 3 of this embodiment is 0.16%, the MgO chlorination rate is 84%, and the MgCl2 loss rate is 10%.

[0106] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A molten chlorination furnace for processing magnesium chloride, characterized in that, include: The furnace shell and the melting chlorination chamber (1), the clarification chamber (2) and the chlorination purification chamber (3) disposed in the furnace shell; The bottom (103) of the melting chlorination chamber is provided with a raw material and reducing agent inlet (101) and a chlorinating agent inlet (102), and the top of the melting chlorination chamber is provided with a flue gas outlet (104). The clarification chamber and the melting chlorination chamber are separated by a first wall (4). On the first wall (4), a first flue gas hole (401), a first liquid flow hole (402) and a slag flow hole (403) are provided from top to bottom. The slag flow hole (403) is located at the lowest point of the bottom wall of the clarification chamber. The clarification chamber (2) and the melting chlorination chamber (1) are connected through the first flue gas hole (401), the first liquid flow hole (402) and the slag flow hole (403). The clarification chamber and the chlorination purification chamber are separated by a second wall (5). On the second wall (5), a second flue gas hole (501) and a second liquid flow hole (502) are provided from top to bottom. The clarification chamber (2) and the chlorination purification chamber (3) are connected through the second flue gas hole (501) and the second liquid flow hole (502). The top of the chlorination purification chamber is provided with a liquid extraction hole (301) and a movable chlorinating agent spray gun (302). The bottom of the side wall of the chlorination purification chamber is provided with a slag discharge port (303). Heating electrodes (6) are provided in the melting chlorination chamber (1), the clarification chamber (2), and the chlorination purification chamber (3).

2. The molten chlorination furnace for processing magnesium chloride according to claim 1, characterized in that, The bottom (103) of the melting chlorination chamber is an inverted cone structure. Preferably, the taper of the bottom (103) of the melting chlorination chamber is 5°-18°. Preferably, a powder spray gun is provided at the raw material and reducing agent inlet (101). Preferably, the powder spray gun forms an angle with the bottom wall of the melting chlorination chamber. Preferably, a chlorinating agent spray gun is provided at the chlorinating agent inlet (102). Preferably, the chlorinating agent spray gun forms an angle with the bottom wall of the melting chlorination chamber.

3. The molten chlorination furnace for processing magnesium chloride according to claim 1, characterized in that, The bottom (103) of the melting chlorination chamber is lower than the bottom of the clarification chamber; the bottom wall (201) of the clarification chamber is sloping, pointing from the second wall (5) to the first wall (4), and the bottom wall (201) of the clarification chamber gradually decreases. The lowest point of the bottom wall of the clarification chamber is connected to the slag discharge hole (403). Preferably, the slope of the bottom wall (201) of the clarification chamber is 7°-12°. Preferably, the slag discharge hole (403) is inclined, pointing from the second wall (5) to the first wall (4), and the slag discharge hole (403) gradually decreases. Preferably, the slope of the slag discharge hole (403) is the same as the slope of the bottom wall (201) of the clarification chamber.

4. The molten chlorination furnace for processing magnesium chloride according to claim 1, characterized in that, The bottom wall (304) of the chlorination purification chamber is sloping, pointing from the first wall (4) to the second wall (5). The bottom wall (304) of the chlorination purification chamber gradually decreases, and the lowest point of the bottom wall of the chlorination purification chamber is connected to the slag discharge port (303). Preferably, the slope of the bottom wall (304) of the chlorination purification chamber is 10°-20°.

5. The molten chlorination furnace for processing magnesium chloride according to claim 1, characterized in that, The chlorination purification chamber (3) has a through hole at the top, and the movable chlorinating agent spray gun (302) is installed in the through hole. The movable chlorinating agent spray gun (302) moves in the up and down direction and is connected to a lifting device.

6. The molten chlorination furnace for processing magnesium chloride according to claim 1, characterized in that, The number of heating electrodes (6) in each chamber is at least two, and the length of the heating electrodes (6) immersed in molten magnesium chloride is 1 / 3 to 2 / 3 of the length of the heating electrodes (6).

7. A method for treating magnesium chloride, characterized in that, The method is carried out in the molten chlorination furnace for processing magnesium chloride according to any one of claims 1 to 6, and the method includes the following steps: The magnesium chloride to be treated is mixed with a reducing agent to obtain a gas-solid mixture for spraying. The gas-solid mixture is then introduced into the melting chlorination chamber, and the chlorinating agent is introduced into the melting chlorination chamber. The heating electrode (6) is turned on, so that the magnesium oxide in the magnesium chloride to be treated is converted into magnesium chloride in the melting chlorination chamber. The liquid in the melting chlorination chamber flows into the clarification chamber and the chlorination purification chamber sequentially from the first liquid flow hole (402) and the second liquid flow hole (502) by gravity, so that the outlet of the movable chlorinating agent spray gun (302) is immersed in the liquid in the chlorination purification chamber, and chlorinating agent is introduced into the movable chlorinating agent spray gun (302). Electrolytic magnesium raw material was extracted from the extraction hole (301).

8. The method according to claim 7, characterized in that, The magnesium chloride to be treated is hydrated magnesium chloride. Preferably, the amount of water of crystallization bound to each mole of magnesium chloride in the magnesium chloride to be treated is less than or equal to 1 mole. Preferably, the reducing agent is at least one selected from coke powder, methane, and carbon monoxide; Preferably, the chlorinating agent is anhydrous hydrogen chloride gas or chlorine gas; preferably, the chlorinating agent is anhydrous hydrogen chloride gas. Preferably, the molar ratio of the magnesium chloride to be treated to the reducing agent is 1:(0.01-0.1). Preferably, the molar ratio of the magnesium chloride to be treated to the chlorinating agent entering the melting chlorination chamber is 1:(0.03-0.15). Preferably, the molar ratio of the magnesium chloride to be treated to the chlorinating agent entering the chlorination purification chamber is 1:(0.01-0.1).

9. The method according to claim 7, characterized in that, The method further includes: adjusting the immersion depth of the heating electrode (6) according to the temperature of the molten pool in each chamber and / or the power of the heating electrode (6); The insertion depth of the movable chlorinating agent spray gun (302) is determined based on the MgO content in the anhydrous magnesium chloride solution in the chlorination purification chamber (3). The higher the MgO content in the anhydrous magnesium chloride solution in the chlorination purification chamber (3), the deeper the insertion depth of the movable chlorinating agent spray gun (302).

10. A method for electrolytically preparing metallic magnesium, characterized in that, The method for treating magnesium chloride includes any one of claims 7 to 9.

Images