CN113104870B - Continuous preparation method of molten salt electrolyte for electrolytic magnesium - Google Patents

Continuous preparation method of molten salt electrolyte for electrolytic magnesium Download PDF

Info

Publication number
CN113104870B
CN113104870B CN202110383198.6A CN202110383198A CN113104870B CN 113104870 B CN113104870 B CN 113104870B CN 202110383198 A CN202110383198 A CN 202110383198A CN 113104870 B CN113104870 B CN 113104870B
Authority
CN
China
Prior art keywords
chloride
magnesium
mixture
ammonium
carnallite
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202110383198.6A
Other languages
Chinese (zh)
Other versions
CN113104870A (en
Inventor
卢旭晨
张志敏
闫岩
王天华
薛立强
李金沙
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hebei Dayou Magnesium Industry Co ltd
Institute of Process Engineering of CAS
Original Assignee
Hebei Dayou Magnesium Industry Co ltd
Institute of Process Engineering of CAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hebei Dayou Magnesium Industry Co ltd, Institute of Process Engineering of CAS filed Critical Hebei Dayou Magnesium Industry Co ltd
Priority to CN202110383198.6A priority Critical patent/CN113104870B/en
Publication of CN113104870A publication Critical patent/CN113104870A/en
Application granted granted Critical
Publication of CN113104870B publication Critical patent/CN113104870B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/26—Magnesium halides
    • C01F5/30—Chlorides
    • C01F5/305—Dehydrating ammonium or alkali magnesium chlorides, e.g. carnalite
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/26—Magnesium halides
    • C01F5/30—Chlorides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/26—Magnesium halides
    • C01F5/30—Chlorides
    • C01F5/32—Preparation of anhydrous magnesium chloride by chlorinating magnesium compounds
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/04—Electrolytic production, recovery or refining of metals by electrolysis of melts of magnesium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2002/00—Crystal-structural characteristics
    • C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
    • C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Landscapes

  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geology (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

The invention discloses a continuous preparation method of molten salt electrolyte for electrolytic magnesium, which comprises the following steps: (1) uniformly mixing a magnesium-containing raw material and ammonium chloride to obtain a mixture of the magnesium-containing raw material and the ammonium chloride; (2) distributing a mixture of a magnesium-containing raw material and ammonium chloride, and heating to prepare a mixture of anhydrous magnesium chloride and low-water ammonium carnallite; (3) uniformly mixing the mixture of the anhydrous magnesium chloride and the low-water ammonium carnallite and other metal chlorides, and heating to prepare a melt containing the anhydrous magnesium chloride, wherein the melt is used as an electrolyte melt for starting an electrolytic cell; (4) and (3) repeating the steps S1 and (2), distributing the mixture of the anhydrous magnesium chloride and the low-water ammonium carnallite obtained in the step S2 and the electrolyte melt with low anhydrous magnesium chloride content generated in the process of preparing the metal magnesium by electrolysis, and heating to prepare the melt containing the anhydrous magnesium chloride to be used as the electrolyte melt in the continuous electrolysis process. The invention can prepare the molten salt electrolyte for electrolyzing magnesium under relatively simple conditions.

Description

Continuous preparation method of molten salt electrolyte for electrolytic magnesium
Technical Field
The invention relates to the technical field of preparation of molten salt electrolytes, in particular to a continuous preparation method of a molten salt electrolyte for electrolytic magnesium.
Background
China is the most abundant world magnesium resource country, and has a large amount of liquid magnesium ores and solid magnesium ores. In the aspect of liquid magnesium ore, during the process of producing the potash fertilizer in Qinghai salt lakeMagnesium chloride hexahydrate (MgCl) in annual waste brine2·6H2O) content reaches 2400-3600 ten thousand tons. A large amount of magnesium chloride hexahydrate resources are piled everywhere to form magnesium hazard locally, and the opening and the utilization of the magnesium chloride hexahydrate are urgent and become hot spots concerned by government departments and various social circles. In the aspect of solid magnesium ore, the storage capacity and the quality of magnesite in the Liaoning Yingkou large stone bridge area of China are the first in the world. However, at present, the mainstream pidgeon magnesium smelting method cannot utilize bischofite or magnesite as raw materials, so that a large amount of liquid and solid magnesium ores are accumulated. The preparation of high-purity anhydrous magnesium chloride from bischofite or magnesite through dehydration/chlorination, and then the preparation of metal magnesium by using a molten salt electrolysis method is a reasonable way for efficiently and economically utilizing magnesium resources. The preparation of the high-purity magnesium electrolyte melt (or the high-purity anhydrous magnesium chloride) is a key link which can be realized by the process. In the process of preparing anhydrous magnesium chloride by heating in an air environment, no matter bischofite is dehydrated or magnesite is chloridized, hydrolysis reaction can be carried out to generate magnesium hydroxychloride or magnesium oxide. Magnesium hydroxychloride or magnesium oxide are very harmful to the subsequent electrolysis process, which can seriously reduce the current efficiency and increase the electrolysis energy consumption.
At present, the methods for preparing high-purity magnesium electrolyte melt (or high-purity anhydrous magnesium chloride) by using bischofite or magnesite comprise the following steps:
(1) and (5) dehydrating under the protection of gas. The gas protection dehydration is to dehydrate magnesium chloride hexahydrate in the atmosphere of hydrogen chloride gas or chlorine gas to obtain high-purity anhydrous magnesium chloride. The magnesium chloride hexahydrate is hydrolyzed to generate hydrogen chloride gas in the heating dehydration process, and from the chemical balance point of view, the magnesium chloride hexahydrate is heated under the hydrogen chloride atmosphere to prevent hydrolysis, so that the anhydrous magnesium chloride is obtained. Chlorine gas can react with hydrolysate magnesium oxide or hydroxyl magnesium chloride at high temperature to generate anhydrous magnesium chloride. Therefore, the hydrogen chloride and chlorine atmosphere is helpful for preparing anhydrous magnesium chloride with higher purity by dehydrating magnesium chloride hexahydrate or chlorinating magnesium oxide. Boyum et al (in detail, U.S. Pat. No. 5, 3742100) use magnesium chloride solution as raw material, concentrate it to about 55% magnesium chloride content for granulation, fluidize and dry it in hot air at 200 deg.C to obtain magnesium chloride dihydrate powder, fluidize and dehydrate it in Anhydrous hydrogen chloride gas at 300 deg.C to obtain Anhydrous magnesium chloride containing magnesium oxide and water content less than 0.2%. The gas protection dehydration process utilizes hydrogen chloride gas to inhibit the hydrolysis of magnesium chloride hexahydrate or utilizes chlorine gas to chlorinate hydrolysis products, and anhydrous magnesium chloride with high purity can be obtained. However, the consumption of hydrogen chloride gas or chlorine gas is large, the corrosion to equipment is large, the requirement on the sealing performance of the equipment is high, the difficulty in purifying the gas is high, and the dehydration process cost is greatly increased.
(2) A magnesite chlorination process. In the traditional IG method, magnesite is used as a raw material, a product obtained after calcination at the temperature of 700-800 ℃ is mixed with coke and a binder and pressed into blocks, and the blocks react with chlorine gas in a chlorination furnace at the temperature of about 1100 ℃ to obtain an anhydrous magnesium chloride melt. Liu Bin et al (see in detail: Liu Bin, anhydrous magnesium chloride and light metal prepared from calcined magnesite 2000: 10: 40-42) studied the influence of calcined condition of calcined magnesite on the activity of magnesium oxide and the influence of activity of magnesium oxide on the rate of chlorination reaction in order to solve the problems of poor air permeability of the material layer of the chlorination furnace, non-uniform material layer, low furnace productivity, etc. Shackleton et al (see in detail: Shackleton CEE, Preparation of anhydrous magnesium chloride, US Patent 4269816) use magnesite as a raw material, carbon monoxide as a reducing agent and chlorine as a chlorinating agent in a packed bed reactor, perform chlorination at 800-. The magnesite chlorination method has low energy consumption and simple equipment, and can be applied and industrialized, but magnesite is easy to crack in the thermal decomposition process, so that the gas permeability of a furnace layer is poor, the productivity of the furnace is low, and the utilization rate of chlorine is low.
(3) Organic solvent method. The organic solvent distillation method utilizes the characteristic that hydrated magnesium chloride is easy to dissolve in certain organic solvents, and adopts distillation to obtain anhydrous organic solution of magnesium chloride, and then the anhydrous magnesium chloride is separated from the organic solvent. Zhang Mumer et al (see, e.g., Zhang D.M. et al, The reduction of magnesium chloride by butanol precipitation, J.Cent Inst. Min. Metal, 1988, 19 (4): 388-394.) dissolve magnesium chloride in butanol to make a solution. Most of the crystal water was first removed by distillation by heating and then butanol was removed by heating to 450 c to obtain anhydrous magnesium chloride with less than 1.5% magnesium oxide. Ootang flood et al (Ootang flood et al, kinetics of leaching calcined magnesite in ethylene glycol solution of ammonium chloride, proceedings of Process engineering, 2007, 7 (5): 928-933) calcines magnesite to obtain magnesium oxide, selectively leaching magnesium oxide with ammonium chloride in ethylene glycol solution to generate magnesium chloride, removing water in the solution by rectification, introducing ammonia gas and magnesium chloride to generate magnesium chloride hexammoniate precipitate, separating the precipitate and washing, and calcining magnesium chloride hexammoniate to obtain anhydrous magnesium chloride. The organic solvent distillation process consumes a large amount of organic solvent to wash the product, and the volatilization of the organic solvent greatly increases the cost of the method.
(4) And (4) a double salt method. The double salt method is to synthesize carnallite or other double salt forms from magnesium chloride hexahydrate or magnesium oxide, and dehydrate the carnallite or other double salt forms by utilizing the characteristic of poor binding capacity of magnesium chloride and crystal water in the double salt to obtain anhydrous magnesium chloride or molten salt containing the anhydrous magnesium chloride. Zhongbo et al (for details, see the literature: Zhongbo et al, anhydrous magnesium chloride is prepared by an ammonium carnallite gas-solid reaction method, applied chemistry, 2005, 22 (8): 874) 878) utilize bischofite solution and magnesium chloride solution filtered by ammonia method magnesium precipitation as raw materials, adopt a crystallization method to prepare ammonium carnallite, and dehydrate the ammonium carnallite at 160 ℃ to obtain low-water ammonium carnallite. Mixing low-water ammonium carnallite and ammonium chloride according to the molar ratio of 1:4, and heating to obtain anhydrous magnesium chloride with the magnesium oxide content of less than 0.1%. \37154OJsuch as Pinna minor et al (see the literature: 37154; Pinna minor, the method for preparing anhydrous magnesium chloride by using ammonium carnallite takes bischofite and ammonium chloride as raw materials to synthesize ammonium carnallite, 1983: 351-. The method consumes a large amount of ammonium chloride in the heating process, the ammonium chloride decomposes to absorb a large amount of heat, and the recovery of the ammonium chloride greatly increases the cost of the method.
In summary, the above-mentioned method for preparing high-purity electrolytic magnesium melt (or high-purity anhydrous magnesium chloride) has the following common problems: (1) there is a lack of dehydration/chlorination commonality studies. Although there are many differences in the reaction mechanism and reaction kinetics between the dehydration of magnesium chloride hexahydrate and the chlorination of magnesium oxide, there are some common problems with both processes: firstly, hydrolysis products of hydroxyl magnesium chloride or magnesium oxide are chlorinated into anhydrous magnesium chloride in the dehydration process of magnesium chloride hexahydrate, and moisture generated by reaction is removed in the chlorination process of magnesium oxide; the problem of dehydration of magnesium chloride hexahydrate can be seen as the dehydration/chlorination of magnesium chloride hydrate containing a certain amount of magnesium oxide or magnesium hydroxychloride, and the problem of chlorination of magnesium oxide can be seen as the chlorination/dehydration of magnesium oxide containing a certain amount of water of crystallization. (2) The reaction mechanism is single. For example, the gas-shielded dehydration of hydrated magnesium chloride utilizes the shielding effect of hydrogen chloride gas or the conversion effect of chlorine gas, and the chlorination process of magnesite utilizes the gas-solid reaction of chlorine gas and magnesite. The single reaction mechanism can cause the purity of the product to seriously depend on the uniform mixing degree of materials and the contact condition of the materials in the reaction process, which can not be strictly ensured in large-scale continuous industrial production, thereby causing the purity of anhydrous magnesium chloride of different batches of products to be unstable. (3) A global protection mechanism is lacking. The raw material magnesium chloride hydrate, the intermediate product ammonium carnallite (intermediate product of magnesium oxide chlorination and dehydration of magnesium chloride hydrate) and the final product anhydrous magnesium chloride are very unstable in the heating process and are easy to hydrolyze or oxidize. Therefore, both bischofite dehydration and magnesia chlorination require a global protection mechanism from the starting material, intermediate product, and final product. (4) There is a lack of general operating conditions that can accommodate the various extreme feed conditions. In the preparation of anhydrous magnesium chloride by dehydration of bischofite or chlorination of magnesium oxide, high water content, high hydrolysate content, low ammonium chloride content and any combination thereof are considered extreme raw materials and need to be strictly avoided. However, the raw materials are easily affected by weather conditions and the sealing condition of the equipment, so that a universal operation condition is needed to be found to eliminate the influence of the extreme raw materials on the purity of the anhydrous magnesium chloride product.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a continuous preparation method of molten salt electrolyte for electrolytic magnesium, aiming at the defects of the prior art, the method utilizes various magnesium-containing materials as raw materials, has very wide requirements on the water content and the hydrolysate content in the raw materials, and can continuously prepare high-purity electrolyte melt for electrolytic magnesium under relatively simple operation conditions.
In order to solve the above technical problems, the present invention comprises:
a continuous preparation method of molten salt electrolyte for electrolyzing magnesium comprises the following steps:
s1, uniformly mixing the magnesium-containing raw material with ammonium chloride to obtain a mixture of the magnesium-containing raw material and the ammonium chloride;
s2, distributing the mixture of the magnesium-containing raw material and ammonium chloride in a reactor according to the following conditions: the ratio of the height of the mixture material to the maximum cross section of the material is 0.35-28.50, the porosity of a particle bed layer formed by the mixture is 0.26-0.70, and the equivalent diameter of a pore channel in the particle bed layer formed by the mixture is 0.01-1.50 mm; supplying heat to the solid material in radial direction by an external heat source, and ensuring that the temperature difference between the radial edge and the center is 12-75 ℃; heating the mixture at 350-590 ℃ for 0.1-5.5 hours to prepare a mixture of anhydrous magnesium chloride and low-water ammonium carnallite;
s3, uniformly mixing the mixture of the anhydrous magnesium chloride and the low-water ammonium carnallite with other metal chlorides, and ensuring that the ratio of the height of the uniformly mixed mixture to the maximum cross section diameter is 0.25-3.50; heating the uniformly mixed mixture at 500-880 ℃ for reaction for 0.2-4.0 hours, and controlling the melting time of the mixture (anhydrous magnesium chloride, low-water ammonium carnallite and other metal chlorides) to be 0.1-1.2 hours to prepare an electrolyte melt for starting the electrolytic cell;
s4, heating the electrolyte melt with low anhydrous magnesium chloride content to 630-880 ℃, and contacting the electrolyte melt with a mixture of anhydrous magnesium chloride and low-water ammonium carnallite in a surface contact manner, wherein the ratio of the height of the mixture to the diameter of a contact surface is kept between 0.10 and 6.50, and the melting time of the mixture is between 0.10 and 3.85 hours; after the melting is finished, heating the melt to 600-900 ℃ and keeping the ratio of the volume of the upper space of the high-temperature melt to the volume of the melt at 0.01-0.95, and heating to prepare the melt containing anhydrous magnesium chloride as an electrolyte for continuously preparing the metal magnesium by electrolysis.
Further, in the step S1, the magnesium-containing raw material is selected from one of the group consisting of: magnesium chloride hydrate; magnesium oxide; ammonium carnallite hydrate; hydrated magnesium chloride and magnesium oxide; magnesium chloride hydrate and ammonium carnallite hydrate; magnesium oxide and ammonium hydroxide carnallite.
Further, when magnesium chloride hydrate is used as the raw material containing magnesium, the addition amount of ammonium chloride is 0.02 to 2.00 parts by weight based on 1.00 part by weight of the addition amount of the magnesium chloride hydrate; when magnesium oxide is used as a raw material containing magnesium, the feeding amount of ammonium chloride is 1.20-8.00 parts by weight based on 1.00 part by weight of the feeding amount of magnesium oxide; when ammonium hydroxide carnallite is used as the raw material containing magnesium, the feeding amount of ammonium chloride is 0.00-1.00 parts by weight based on 1.00 part by weight of the feeding amount of the ammonium hydroxide carnallite; when hydrated magnesium chloride and magnesium oxide are used as magnesium-containing raw materials, the feeding amount of ammonium chloride is 0.08-6.50 parts by weight based on the total feeding amount of the hydrated magnesium chloride and the magnesium oxide being 1.00 part by weight; when the magnesium chloride hydrate and the ammonium hydroxide carnallite are used as magnesium-containing raw materials, the feeding amount of the ammonium chloride is 0.00-1.25 parts by weight based on the total feeding amount of the magnesium chloride hydrate and the ammonium hydroxide carnallite being 1.00 part by weight; when magnesium oxide and ammonium hydroxide carnallite are used as raw materials containing magnesium, the feeding amount of ammonium chloride is 0.45-5.50 parts by weight based on the total feeding amount of the magnesium oxide and the ammonium hydroxide carnallite being 1.00 part by weight.
Further, in the step S2, the anhydrous magnesium chloride is contained in the mixture of anhydrous magnesium chloride and low-water ammonium carnallite in an amount of 10.00 to 75.00 wt.%; the low water ammonium carnallite has a water content of less than 10.5wt.%, and the low water ammonium carnallite has an ammonium chloride content of 3.5-35.5 wt.%.
Further, in the step S3, the total amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite added is 1.00 part by weight, and the amount of the other metal chlorides added is 1.50-9.00 parts by weight.
Further, in the step S3, the other metal chloride is selected from one of the group consisting of: sodium chloride; potassium chloride; sodium chloride and potassium chloride; sodium chloride, potassium chloride and calcium chloride; sodium chloride, potassium chloride, calcium chloride and barium chloride.
Further, in the step S4, the sum of the contents of potassium chloride and sodium chloride in the electrolyte melt with low anhydrous magnesium chloride content generated in the process of electrolytically preparing the metallic magnesium is 42-80wt.% and the solidification temperature of the electrolyte melt is 450-650 ℃, as the raw material for continuously preparing the electrolyte melt.
Further, in the step S4, the electrolyte melt having a low anhydrous magnesium chloride content is charged in an amount of 2.20 to 6.80 parts by weight based on 1.00 part by weight of the charged amount of the mixture of anhydrous magnesium chloride and low anhydrous ammonium carnallite.
Further, in the step S4, the ammonium chloride released during the continuous production process is recovered and returned to the step S1 for reuse.
The invention has the beneficial effects that:
the invention has the following advantages: (1) the universality of the operation process. Through chlorination studies of magnesium oxide and magnesium hydroxychloride and dehydration studies of magnesium chloride hydrate and ammonium carnallite hydrate, a general reaction mechanism of chlorination/dehydration-transformation-protection is discovered. Therefore, the invention can prepare the high-purity anhydrous magnesium chloride-containing electrolyte melt under a set of general operation conditions in the chlorination/dehydration process of various raw materials, thereby greatly simplifying the difficulty of the operation process; (2) the versatility of the raw materials. When the anhydrous magnesium chloride or the electrolyte melt for magnesium electrolysis is prepared by the traditional method, the hydrolysis product in the product is greatly beyond the electrolysis requirement easily because the water content in the raw materials and/or the hydrolysis product content are high. However, the present invention does not have any requirement for the water content and hydrolysate content of the feedstock, since the commonality of the chlorination and dehydration processes is found. Magnesium chloride hexahydrate (MgCl) without dehydration treatment2·6H2O) or ammonium carnallite (NH)4Cl·MgCl2·6H2O) and pure magnesia material with 100wt.% of hydrolysate content can be used as the raw material of the invention; (3) the multiple reaction mechanisms ensure the high purity and the quality stability of the product. By utilizing the coordination of a material distribution mode, a material structure, a heating mode and the likeThe coexistence of a plurality of reaction mechanisms in the heating process ensures that the purity of the product is not influenced by the uniform mixing degree of the materials, thereby ensuring the stability of the quality of the products in different batches; (4) the whole protection mechanism forms multiple guarantees of the product purity. In the process of heating and preparing the electrolyte melt, different protection mechanisms are formed at low temperature, medium temperature and high temperature, and the whole preparation process is protected by carrying out transition and connection on the protection mechanisms. The whole-process protection forms multiple guarantees on the purity of the product, and ensures that high-purity electrolyte melt can be obtained even under the condition of adopting extreme raw materials (such as high moisture content and high content of hydrolysis products).
Drawings
FIG. 1 is a process scheme of a continuous preparation method of a molten salt electrolyte for electrolytic magnesium according to the present invention;
FIG. 2 is an XRD (X-ray diffraction) spectrum of an electrolyte for starting an electrolytic cell, which is prepared by taking magnesium chloride hexahydrate and ammonium chloride as raw materials and taking potassium chloride as other metal chlorides;
FIG. 3 is an XRD spectrum of an electrolyte for continuous electrolytic magnesium prepared from magnesium chloride hexahydrate and ammonium chloride;
FIG. 4 is an XRD spectrum of an electrolyte for a start-up electrolyzer prepared from hydrated magnesium chloride and ammonium chloride as raw materials and sodium chloride as other metal chlorides;
FIG. 5 is an XRD spectrum of an electrolyte for continuous electrolytic magnesium prepared from hydrated magnesium chloride and ammonium chloride;
FIG. 6 is an XRD spectrum of an electrolyte for a start-up electrolyzer prepared from magnesium oxide and ammonium chloride as raw materials and sodium chloride as other metal chlorides;
FIG. 7 is an XRD spectrum of an electrolyte for continuous electrolytic magnesium prepared from magnesium oxide and ammonium chloride.
Detailed Description
For the purpose of promoting an understanding of the invention, reference will now be made in detail to the present embodiments of the invention, examples of which are illustrated in the accompanying drawings. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
As shown in fig. 1, the continuous preparation method of the molten salt electrolyte for electrolytic magnesium provided by the invention comprises the following specific preparation processes:
the method comprises the following steps: uniformly mixing a magnesium-containing raw material (one selected from the following components: magnesium chloride hydrate, magnesium oxide, ammonium hydroxide carnallite, magnesium chloride hydrate and magnesium oxide, magnesium chloride hydrate and ammonium hydroxide carnallite, magnesium oxide and ammonium hydroxide carnallite) with ammonium chloride to obtain a mixture of the magnesium-containing raw material and the ammonium chloride;
in the first step, when magnesium chloride hydrate is used as the raw material containing magnesium, the addition amount of ammonium chloride is 0.02 to 2.00 parts by weight, preferably 0.05 to 1.80 parts by weight, and more preferably 0.10 to 1.50 parts by weight, based on 1.00 part by weight of the addition amount of the magnesium chloride hydrate; when magnesium oxide is used as the raw material containing magnesium, the amount of ammonium chloride added is 1.20 to 8.00 parts by weight, preferably 1.40 to 7.30 parts by weight, and more preferably 1.80 to 6.80 parts by weight, based on 1.00 part by weight of magnesium oxide; when ammonium hydroxide carnallite is used as the raw material containing magnesium, the addition amount of ammonium chloride is 0.00 to 1.00 part by weight, preferably 0.02 to 0.85 part by weight, and more preferably 0.05 to 0.70 part by weight, based on 1.00 part by weight of the addition amount of ammonium hydroxide carnallite; when hydrated magnesium chloride and magnesium oxide are used as the raw materials containing magnesium, the amount of ammonium chloride added is 0.08 to 6.50 parts by weight, preferably 0.10 to 6.00 parts by weight, and more preferably 0.18 to 5.00 parts by weight, based on 1.00 part by weight of the sum of the amounts of hydrated magnesium chloride and magnesium oxide added; when magnesium chloride hydrate and ammonium hydroxide carnallite are used as the raw materials containing magnesium, the feeding amount of ammonium chloride is 0.00-1.25 parts by weight, preferably 0.10-1.00 parts by weight, and more preferably 0.25-0.85 parts by weight, based on the total feeding amount of the magnesium chloride hydrate and the ammonium hydroxide carnallite being 1.00 part by weight; when magnesium oxide and ammonium hydroxide carnallite are used as the raw material containing magnesium, the amount of ammonium chloride added is 0.45 to 5.50 parts by weight, preferably 0.70 to 4.20 parts by weight, and more preferably 0.90 to 3.60 parts by weight, based on 1.00 part by weight of the sum of the amounts of magnesium oxide and ammonium hydroxide carnallite added.
Step two: the mixture of the magnesium-containing raw material and ammonium chloride is distributed in a reactor according to the following conditions: the ratio of the height of the material to the maximum cross section of the material is 0.35-28.50, the porosity of the particle bed layer formed by the mixture is 0.26-0.70, and the equivalent diameter of the pore channel in the particle bed layer formed by the mixture is 0.01-1.50 mm. And radially supplying heat to the solid material by an external heat source, and ensuring that the temperature difference between the radial edge and the center is 12-75 ℃. Heating the mixture at 350-590 ℃ for 0.1-5.5 hours to prepare a mixture of anhydrous magnesium chloride (with a content of 10.00-75.00 wt.%) and a low ammonium carnallite mixture (with a water content of less than 10.5wt.%, and an ammonium chloride content of 3.5-35.5 wt.%);
in the second step, the ratio of the material height of the mixture of the magnesium-containing raw material and the ammonium chloride to the maximum cross-sectional diameter of the material is preferably 0.70 to 25.00, and more preferably 1.30 to 21.50. The porosity of the granular bed layer consisting of the mixture of the magnesium-containing raw material and the ammonium chloride is preferably 0.30 to 0.65, more preferably 0.40 to 0.55. The equivalent diameter of the cell channels in the particle bed layer composed of the mixture of the magnesium-containing raw material and the ammonium chloride is preferably 0.03-1.20mm, and more preferably 0.05-1.05 mm.
In the second step, the heating temperature is preferably 360-570 ℃, and more preferably 380-550 ℃; the heating time is preferably 0.3 to 5.0 hours, and more preferably 0.8 to 4.0 hours. The temperature difference between the radial edge and the center of the material is preferably 15 to 70 ℃ and more preferably 18 to 65 ℃. The amount of anhydrous magnesium chloride in the mixture of anhydrous magnesium chloride and low-water ammonium carnallite is preferably from 15.00 to 68.50wt.%, more preferably from 18.50 to 58.50 wt.%. Preferably the water content in the low water ammonium carnallite is less than 9.5wt.%, more preferably less than 8.7 wt.%; the ammonium chloride content of the low-water ammonium carnallite is preferably 5.5 to 33.5wt.%, more preferably 6.8 to 32.0 wt.%.
Step three: the anhydrous magnesium chloride, the low-water ammonium carnallite and other metal chlorides are uniformly mixed, and the ratio of the height of the mixture material to the maximum cross section diameter is ensured to be 0.25-3.50. Heating and reacting the mixture at the temperature of 500-880 ℃ for 0.2-4.0 hours, and controlling the melting time of the mixture to be 0.1-1.2 hours to prepare an electrolyte melt for starting the electrolytic cell;
in the third step, the amount of the other metal chloride to be added is 1.50 to 9.00 parts by weight, preferably 2.00 to 7.80 parts by weight, and more preferably 2.50 to 6.50 parts by weight, based on 1.00 part by weight of the total amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite to be added. The heating temperature is preferably 550-850 ℃, and more preferably 600-800 ℃; the heating time is preferably 0.5 to 3.5 hours, and more preferably 0.8 to 2.8 hours. The ratio of the height of the mixture of anhydrous magnesium chloride, low-water ammonium carnallite and other metal chlorides to the maximum cross-sectional diameter of the material is preferably 0.30 to 3.20, and more preferably 0.50 to 2.85. The melting time of the mixture of anhydrous magnesium chloride, low-water ammonium carnallite and other metal chlorides is preferably 0.2 to 1.0 hour, and more preferably 0.3 to 0.8 hour.
Step four: the electrolyte melt with low anhydrous magnesium chloride content is generated in the process of preparing the metal magnesium by electrolysis, and can be used as a raw material for continuously preparing the electrolyte melt when the sum of the potassium chloride content and the sodium chloride content in the melt is 42-80wt.% and the solidification temperature is 450-650 ℃. The electrolyte melt with low anhydrous magnesium chloride content is heated to the temperature of 630-880 ℃, and is in surface contact with the mixture of anhydrous magnesium chloride and low-water ammonium carnallite, the ratio of the height of the mixture to the diameter of the contact surface is kept between 0.10 and 6.50, and the melting time of the mixture is kept between 0.10 and 3.85 hours. After the melting is finished, the melt is heated to 600-900 ℃ and the ratio of the volume of the upper space of the high-temperature melt to the volume of the melt is kept between 0.01 and 0.95 so as to be used as an electrolyte for continuously preparing the metal magnesium by electrolysis. The ammonium chloride released during the continuous production process is recovered and returned to step S1 for reuse.
In step four, the sum of the contents of potassium chloride and sodium chloride in the electrolyte melt with low anhydrous magnesium chloride content produced in the process of electrolytically preparing metallic magnesium is preferably 45 to 75wt.%, and more preferably 50 to 70 wt.%. The solidification temperature of the electrolyte melt with a low anhydrous magnesium chloride content is preferably 480-600 ℃, and more preferably 495-580 ℃. The electrolyte melt temperature with a low anhydrous magnesium chloride content is preferably 650-850 ℃, and more preferably 680-800 ℃. The electrolyte melt having a low anhydrous magnesium chloride content is charged in an amount of 2.20 to 6.80 parts by weight, preferably 2.50 to 6.50 parts by weight, and more preferably 2.80 to 6.00 parts by weight, based on 1.00 part by weight of the charged amount of the mixture of anhydrous magnesium chloride and low aqueous ammonium carnallite. The mixture of anhydrous magnesium chloride and low-water ammonium carnallite is in surface contact with the electrolyte melt with low anhydrous magnesium chloride content, and the ratio of the height of the mixture to the diameter of the contact surface is preferably 0.50-6.00, and more preferably 0.80-5.50. The melting time of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite is preferably 0.30 to 3.50 hours, and more preferably 0.60 to 3.00 hours. The heating temperature for heating and preparing the anhydrous magnesium chloride-containing melt is preferably 630-870 ℃, and more preferably 650-820 ℃. The ratio of the volume of the headspace above the anhydrous magnesium chloride-containing melt to the volume of the melt is preferably 0.03 to 0.90, more preferably 0.08 to 0.75.
The method has the following general principle: (1) various reaction modes are provided. In the heating process of the magnesium-containing raw material and ammonium chloride, when a certain material distribution mode, a certain heating mode, a certain material structure and a certain ammonium chloride decomposition release rate are met, the reaction between the materials is converted from a simple solid-solid phase reaction into a solid-solid and gas-solid phase reaction. For example, under certain conditions, magnesium chloride hydrate or low-water ammonium carnallite and ammonium chloride simultaneously have a solid-solid reaction between magnesium hydroxychloride and ammonium chloride, a solid-solid reaction between magnesium oxide and ammonium chloride, a gas-solid reaction between ammonium chloride and magnesium oxide/magnesium hydroxychloride, and a gas-solid reaction between hydrogen chloride and magnesium oxide/magnesium hydroxychloride. By adding a reaction mode, the double functions of ammonium chloride chlorination (solid-solid reaction and gas-solid reaction) and dehydration (gas-solid reaction) can be realized, so that the method is not only suitable for various magnesium-containing raw materials, but also suitable for materials under various extreme conditions (such as high water content, high hydrolysate content and the like); (2) various purity assurance mechanisms. Under certain material structure, heating mode and reaction conditions, when the mixture of the magnesium-containing raw material and ammonium chloride is heated at low temperature, the kinetics of chlorination/dehydration conforms to an unreacted nuclear model: the water content and ammonium chloride content of the external material are lower than those of the internal core raw material, and the internal core gradually becomes smaller to be eliminated along with the reaction. Thus, the combination of the control of the decomposition release rate of the internal ammonium chloride by the external material and the protection of the external material by the protective atmosphere generated by the decomposition release of the ammonium chloride in the internal material is formed; when the reaction is carried out to the medium temperature, the conversion of the hydrolysate to anhydrous magnesium chloride (including gas-solid reaction of gaseous ammonium chloride and the hydrolysate, gas-solid reaction of hydrogen chloride and the hydrolysate and solid-solid reaction of ammonium chloride and the hydrolysate) can be realized by controlling the material structure and the heating mode, so that the purity of the material at the medium temperature is ensured; when the reaction is carried out to high temperature, the liquid molten salt protection of the material can be realized by controlling the contact mode, the melting speed and the material structure of the solid material and the high-temperature melt. The concentration of the anhydrous magnesium chloride is greatly reduced by the liquid molten salt, and the unstable anhydrous magnesium chloride is efficiently protected by the compact structure of the molten salt. Thus, the synergy-transformation-protection forms a whole protection for the preparation process, forms a plurality of product purity guarantee mechanisms, and can ensure the quality of the product even if one or two mechanisms are out of order.
The inventor finds out through extensive research that the principle of continuous production by using the method is as follows: continuous production of magnesium metal by electrolysis requires first the use of solid materials to prepare the electrolyte melt for starting the cell. In the invention, a magnesium-containing raw material, ammonium chloride and other metal chlorides are used as raw materials, and the characteristic that potassium chloride or/and sodium chloride form double salt with magnesium chloride in the heating process is utilized to prepare high-purity anhydrous magnesium chloride-containing electrolyte melt which can be used as a raw material for starting an electrolytic cell. In order to ensure continuous production in the electrolytic process, the invention utilizes the electrolyte melt containing low anhydrous magnesium chloride content generated in the electrolytic process as a raw material, and realizes the rapid molten salt protection of the anhydrous material by controlling the contact mode of the solid material and the high-temperature melt, the melting rate of the solid material and the structure of the solid material, so that the prepared high-temperature melt containing the anhydrous magnesium chloride can be used as the electrolyte for continuous production.
The present invention includes the following examples.
The molecular expression of the hydrated magnesium chloride in the invention is MgCl2·nH2O, wherein 6 is not less thannIs greater than 0. Molecular NH of ammonium hydroxide carnallite as described in the invention4Cl·MgCl2·mH2O, wherein 6 is not less thanm＞0。
In the present invention, the content of the hydrolysate is less than 0.1wt% based on 100% of anhydrous magnesium chloride (i.e., the upper limit of the content of the hydrolysate contained in anhydrous magnesium chloride that is acceptable in the most advanced multi-polar electrolytic cells currently used in the electrolytic production of magnesium metal). Therefore, the high-purity electrolytic magnesium electrolyte melt prepared by the method can be directly used for preparing metal magnesium by electrolysis of a multi-polar electrolytic cell.
The products prepared according to the invention were tested according to the following method.
1. Titration method for determining precipitate of sample water solution to determine content of hydrolysate in anhydrous magnesium chloride
The anhydrous magnesium chloride sample obtained was dissolved in water and the aqueous solution was filtered repeatedly at least three times with four sheets of filter paper of a quantitative size phi 90mm until the filtrate was particularly clear. Repeatedly washing the filter paper with deionized water to remove magnesium ions attached to the filter paper, putting the filter paper containing hydrolysate particles into a beaker after washing, adding excessive prepared 1:100 sulfuric acid, heating the beaker on an electric furnace to boil and standing for five minutes to complete the reaction. The solution in the beaker was subjected to EDTA titration to determine the content of magnesium ions, thereby obtaining the content of hydrolysate in anhydrous magnesium chloride.
2. The phase of each substance was determined by X-ray diffraction (XRD) using an X-ray diffractometer (model: X' Pert PRO MPD; manufacturer: Philips).
Typical but non-limiting examples of the invention are as follows:
example 1
1000g of MgCl2·6H2O and 20g of ammonium chloride (the addition amount of the ammonium chloride is 0.02 part by weight based on 1.00 part by weight of the addition amount of the magnesium chloride hydrate) were uniformly mixed, and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 28.50, the porosity of the particle bed was 0.58, and the equivalent diameter of the channels in the particle bed was 1.50 mm. The above mixture of materials was heated at 350 ℃ for 5.0 hours (external heating, material edge to center temperature difference of 24 ℃), and a mixture of anhydrous magnesium chloride and low water ammonium carnallite was prepared. The anhydrous magnesium chloride content of the mixture was 10.00wt.% and the low water ammonium carnallite content was lowThe water and ammonium chloride contents were 9.85wt.% and 28.4wt.%, respectively. An electrolyte melt for starting the electrolytic cell was prepared by uniformly mixing 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite with 600g of potassium chloride (the amount of potassium chloride added was 3.00 parts by weight based on 1.00 part by weight of the total amount of the anhydrous magnesium chloride and low-water ammonium carnallite added), the ratio of the height of the mixture to the maximum cross-sectional diameter was 2.50, and the mixture was heated at 550 ℃ for 1.5 hours while maintaining the melting rate of the mixture for 1.5 hours. The electrolyte melt with a low hydrated magnesium chloride content (sum of potassium chloride and sodium chloride contents 45wt.%, solidification temperature 486 ℃) obtained after electrolysis was kept at 650 ℃ and 500g of the electrolyte melt was brought into surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the top (the charge amount of the electrolyte melt was 2.50 parts by weight based on 1.00 part by weight of the charge amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), keeping the melting time of the solid material at 1.50 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the volume of the melt at 0.08, heating to 700 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 1 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for the start-up electrolytic cell is 0.004wt.%, and XRD (X-ray diffraction) is shown in figure 2; the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium is 0.002wt.%, and the XRD (X-ray diffraction) is shown in figure 3.
Example 2
1000g of MgCl2·2.4H2O and 2000g of ammonium chloride (the amount of ammonium chloride added was 2.00 parts by weight based on 1.00 part by weight of the magnesium chloride hydrate) were mixed uniformly and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 25.6, the porosity of the particle bed was 0.26, and the equivalent diameter of the channels in the particle bed was 0.17 mm. Heating the above mixture at 450 deg.C for 0.8 hr (external heating, material edge and center temperature difference of 68 deg.C), and preparing to obtain anhydrous magnesium chloride and low water content ammonium lightA mixture of halorocks. The anhydrous magnesium chloride content of the mixture was 47.80wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 2.16wt.% and 32.5wt.%, respectively. An electrolyte melt for starting the electrolytic cell was prepared by uniformly mixing 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite with 1800g of sodium chloride (the amount of sodium chloride added was 9.00 parts by weight based on 1.00 part by weight of the total amount of the anhydrous magnesium chloride and low-water ammonium carnallite added), the ratio of the height of the mixture to the maximum cross-sectional diameter was 0.25, and the mixture was heated at 880 ℃ for 0.2 hour while maintaining the melting rate of the mixture for 0.1 hour. The electrolyte melt with low hydrated magnesium chloride content (the sum of the contents of potassium chloride and sodium chloride is 42wt.%, the solidification temperature is 450 ℃) obtained after electrolysis is kept at 630 ℃ and 440g of the electrolyte melt is in surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the upper part (the charging amount of the electrolyte melt is 2.20 parts by weight based on 1.00 part by weight of the charging amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), and the melting time of the solid material is kept at 1.00 hour. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the volume of the melt at 0.58, heating to 800 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the metal magnesium.
The product obtained in example 2 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for the start-up electrolytic cell is 0.06wt.%, and XRD thereof is shown in figure 4; the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuous electrolytic magnesium metal is 0.03wt.%, and XRD thereof is shown in figure 5.
Example 3
1000g of magnesium oxide was uniformly mixed with 8000g of ammonium chloride (the amount of ammonium chloride added was 8.00 parts by weight based on 1.00 part by weight of the magnesium oxide), and the mixture was distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 0.35, the porosity of the particle bed was 0.34, and the equivalent diameter of the channels in the particle bed was 0.01 mm. The above mixture of materials was heated at 400 ℃ for 2.5 hours (external heating, material edge to center temperature difference of 12 ℃), to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 65.50wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 0.0wt.% and 30.5wt.%, respectively. The mixture of 200g of the above anhydrous magnesium chloride and low-moisture ammonium carnallite was mixed with 300g of sodium chloride and potassium chloride (the total amount of the charged anhydrous magnesium chloride and low-moisture ammonium carnallite was 1.00 part by weight, the amount of the charged sodium chloride and potassium chloride was 1.50 parts by weight), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 3.35, the mixture was heated at 750 ℃ for 4.0 hours while maintaining the melting rate of the mixture for 1.2 hours, and an electrolyte melt for starting the electrolytic cell was prepared. The electrolyte melt having a low hydrated magnesium chloride content (sum of potassium chloride and sodium chloride contents: 80wt.%, solidification temperature: 650 ℃) obtained after electrolysis was kept at 730 ℃ and 1360g of the electrolyte melt was brought into surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from above (the charge amount of the electrolyte melt was 6.80 parts by weight based on 1.00 part by weight of the charge amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), keeping the melting time of the solid material at 0.10 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the volume of the melt at 0.95, heating to 900 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the metal magnesium.
The product obtained in example 3 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for the start-up electrolytic cell is 0.003wt.%, and XRD (XRD) is shown in figure 6; the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuous electrolytic magnesium metal is 0.01wt.%, and XRD thereof is shown in figure 7.
Example 4
1000g of magnesium oxide was uniformly mixed with 1200g of ammonium chloride (the amount of ammonium chloride added was 1.20 parts by weight based on 1.00 part by weight of the amount of magnesium oxide added), and the mixture was distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 5.86, the porosity of the particle bed was 0.70, and the equivalent diameter of the channels in the particle bed was 0.86 mm. The above mixture of materials was heated at 570 ℃ for 0.3 hour (external heating, material edge to center temperature difference of 46 ℃), to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 75.00wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 0.0wt.% and 15.8wt.%, respectively. An electrolyte melt for starting the electrolytic cell was prepared by uniformly mixing 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite with 1800g of sodium chloride, potassium chloride and calcium chloride (the amount of sodium chloride, potassium chloride and calcium chloride added was 9.00 parts by weight based on 1.00 part by weight of the total amount of the anhydrous magnesium chloride and low-water ammonium carnallite charged), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 3.20, and the mixture was heated at 820 ℃ for 2.8 hours while maintaining the melting rate of the mixture at 0.8 hour. The electrolyte melt with low hydrated magnesium chloride content (45 wt.% of the sum of the potassium chloride and sodium chloride, 636 ℃ of solidification) obtained after electrolysis was kept at 790 ℃, and 500g of the electrolyte melt was brought into surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the lower part (the charge amount of the electrolyte melt was 2.50 parts by weight based on 1.00 part by weight of the charge amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), and the melting time of the solid material was kept at 3.85 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the volume of the melt at 0.01, heating to 650 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 4 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.006wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.009 wt.%.
Example 5
1000g NH4Cl·MgCl2·6H2O and 0g of ammonium chloride (the feeding amount of the ammonium chloride is 0.00 part by weight based on 1.00 part by weight of the feeding amount of the ammonium carnallite) are uniformly mixed, and the mixture is distributed according to the following mode: material height and material of mixtureThe ratio of the maximum cross-sectional diameter is 16.85, the porosity of the particle bed layer is 0.65, and the equivalent diameter of the pore channel in the particle bed layer is 1.08 mm. The above mixture of materials was heated at 550 ℃ for 3.5 hours (external heating, material edge to center temperature difference of 75 ℃) to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 35.40wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 5.79wt.% and 4.8wt.%, respectively. 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite was mixed with 1000g of sodium chloride, potassium chloride, calcium chloride and barium chloride (the total amount of the added anhydrous magnesium chloride and low-water ammonium carnallite was 1.00 part by weight, the amount of the added sodium chloride, potassium chloride, calcium chloride and barium chloride was 5.00 parts by weight), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 1.80, the mixture was heated at 720 ℃ for 3.5 hours while maintaining the melting rate of the mixture at 0.85 hour, and an electrolyte melt for starting the electrolytic cell was prepared. The electrolyte melt with low hydrated magnesium chloride content (the sum of the contents of potassium chloride and sodium chloride is 58wt.%, the solidification temperature is 648 ℃) obtained after electrolysis was kept at 840 ℃, 560g of the electrolyte melt was brought into surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the lower part (the charging amount of the electrolyte melt was 2.80 parts by weight based on 1.00 part by weight of the charging amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), and the melting time of the solid material was kept at 3.50 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the volume of the melt at 0.38, heating to 780 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 5 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.07wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.09 wt.%.
Example 6
1000g NH4Cl·MgCl2·1.4H2O with 1000g ammonium chloride (low water ammonium light)1.00 part by weight of the halolite and 1.00 part by weight of the ammonium chloride) and the mixture is uniformly mixed and distributed according to the following mode: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 1.35, the porosity of the particle bed was 0.40, and the equivalent diameter of the channels in the particle bed was 0.54 mm. The above mixture of materials was heated at 380 ℃ for 3.2 hours (external heating, material edge to center temperature difference of 29 ℃) to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 27.20wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 0.05wt.% and 26.79wt.%, respectively. 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite was mixed with 800g of sodium chloride, potassium chloride, calcium chloride and barium chloride (the total amount of the added anhydrous magnesium chloride and low-water ammonium carnallite was 1.00 part by weight, the amount of the added sodium chloride, potassium chloride, calcium chloride and barium chloride was 4.00 parts by weight), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 2.70, the mixture was heated at 750 ℃ for 3.8 hours while maintaining the melting rate of the mixture at 0.92 hours, and an electrolyte melt for starting the electrolytic cell was prepared. The electrolyte melt with low hydrated magnesium chloride content (the sum of the contents of potassium chloride and sodium chloride is 70wt.%, and the solidification temperature is 628 ℃) obtained after electrolysis is kept at 820 ℃, 1200g of the electrolyte melt is in surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the lower part (the charging amount of the mixture of the anhydrous magnesium chloride and the low-water ammonium carnallite is 1.00 part by weight, and the charging amount of the electrolyte melt is 6.00 parts by weight), and the melting time of the solid material is kept for 3.20 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the melt body at 0.07, heating to 800 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the metal magnesium.
The product obtained in example 6 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.01wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.02 wt.%.
Example 7
1000g of MgCl2·1.2H2The mixture of O and magnesium oxide was uniformly mixed with 80g of ammonium chloride (0.08 parts by weight of ammonium chloride based on 1.00 parts by weight of the total amount of the charged magnesium chloride hydrate and magnesium oxide) and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 5.85, the porosity of the particle bed was 0.58, and the equivalent diameter of the channels in the particle bed was 0.96 mm. The above mixture of materials was heated at 480 ℃ for 2.4 hours (external heating, material edge to center temperature difference of 47 ℃), to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 18.70wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 1.70wt.% and 23.69wt.%, respectively. An electrolyte melt for starting the electrolytic cell was prepared by uniformly mixing 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite with 600g of sodium chloride and potassium chloride (the amount of sodium chloride, potassium chloride, calcium chloride and barium chloride added was 3.00 parts by weight based on 1.00 part by weight of the total amount of the anhydrous magnesium chloride and low-water ammonium carnallite added), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 2.50, and the mixture was heated at 820 ℃ for 0.6 hour while maintaining the melting rate of the mixture at 0.78 hour. The electrolyte melt with low hydrated magnesium chloride content (sum of potassium chloride and sodium chloride content is 68wt.%, solidification temperature is 615 ℃) obtained after electrolysis was kept at 800 ℃, 1000g of the electrolyte melt was brought into surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the lower part (the charge amount of the electrolyte melt was 5.00 parts by weight based on 1.00 part by weight of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), and the melting time of the solid material was kept at 2.80 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the melt body at 0.15, heating to 780 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 7 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.05wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.01 wt.%.
Example 8
1000g of MgCl2·6.0H2The mixture of O and magnesium oxide was uniformly mixed with 6500g of ammonium chloride (6.50 parts by weight of ammonium chloride based on 1.00 part by weight of the total amount of charged magnesium chloride hydrate and magnesium oxide) and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 2.80, the porosity of the particle bed was 0.50, and the equivalent diameter of the pore channels in the particle bed was 0.53 mm. The above mixture of materials was heated at 550 ℃ for 1.8 hours (external heating, material edge to center temperature difference of 18 ℃), to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 14.80wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 5.90wt.% and 18.80wt.%, respectively. An electrolyte melt for starting the electrolytic cell was prepared by uniformly mixing 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite with 1000g of sodium chloride and potassium chloride (the amount of sodium chloride, potassium chloride, calcium chloride and barium chloride added was 5.00 parts by weight based on 1.00 part by weight of the total amount of the anhydrous magnesium chloride and low-water ammonium carnallite added), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 1.80, the mixture was heated at 800 ℃ for 0.5 hour while maintaining the melting rate of the mixture at 0.95 hour. The electrolyte melt with low hydrated magnesium chloride content (the sum of the contents of potassium chloride and sodium chloride is 65wt.%, the solidification temperature is 610 ℃) obtained after electrolysis is kept at 780 ℃ and 1000g of the electrolyte melt is in surface contact with 200g of the mixture of anhydrous magnesium chloride and low-moisture ammonium carnallite from the lower part (the charging amount of the electrolyte melt is 5.00 parts by weight based on 1.00 part by weight of the charging amount of the mixture of anhydrous magnesium chloride and low-moisture ammonium carnallite), and the melting time of the solid material is kept at 2.30 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the melt body at 0.27, heating to 760 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 8 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.04wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.02 wt.%.
Example 9
1000g of MgCl2·6.0H2O and NH4Cl·MgCl2·6.0H2The mixture of O was mixed uniformly with 1250g of ammonium chloride (1.25 parts by weight of ammonium chloride based on 1.00 part by weight of the total amount of the charged magnesium chloride hydrate and ammonium carnallite hydrate) and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 2.50, the porosity of the particle bed was 0.48, and the equivalent diameter of the channels in the particle bed was 0.68 mm. The above mixture of materials was heated at 500 ℃ for 1.2 hours (external heating, 23 ℃ difference between edge and center of material) to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 10.80wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 6.70wt.% and 14.70wt.%, respectively. 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite was mixed with 800g of sodium chloride and potassium chloride (the total amount of the added anhydrous magnesium chloride and low-water ammonium carnallite was 1.00 part by weight, the amount of the added sodium chloride and potassium chloride was 4.00 parts by weight), the ratio of the height of the mixed material to the maximum cross-sectional diameter was 2.40, the mixture was heated at 790 ℃ for 0.4 hour while maintaining the melting rate of the mixture at 0.80 hour, and an electrolyte melt for starting the electrolytic cell was prepared. The electrolyte melt with low hydrated magnesium chloride content (the sum of the contents of potassium chloride and sodium chloride is 59wt.%, the solidification temperature is 598 ℃) obtained after electrolysis is kept at 700 ℃, 800g of the electrolyte melt is in surface contact with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the upper part (the charging amount of the electrolyte melt is 4.00 parts by weight based on 1.00 part by weight of the charging amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite), and the melting time of the solid material is kept to be 2.00 hours. The ratio of the volume of the headspace above the high-temperature melt obtained above to the melt volume was kept at 0.19 and heated toPreparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal at 700 ℃.
The product obtained in example 9 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.08wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.05 wt.%.
Example 10
1000g of MgCl2·1.4H2O and NH4Cl·MgCl2·2.7H2The mixture of O was mixed uniformly with 0g of ammonium chloride (0 part by weight of ammonium chloride based on 1.00 part by weight of the total amount of the charged magnesium chloride hydrate and ammonium carnallite hydrate) and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 1.50, the porosity of the particle bed was 0.38, and the equivalent diameter of the channels in the particle bed was 0.71 mm. The above mixture of materials was heated at 600 ℃ for 0.8 hour (external heating, material edge to center temperature difference of 38 ℃) to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 15.60wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 5.90wt.% and 31.20wt.%, respectively. 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite 1200g of sodium chloride and potassium chloride were mixed uniformly (the total amount of the charged anhydrous magnesium chloride and low-water ammonium carnallite was 1.00 part by weight, the amount of the charged sodium chloride and potassium chloride was 4.00 parts by weight), the ratio of the height of the mixture to the maximum cross-sectional diameter was 1.60, the mixture was heated at 830 ℃ for 0.6 hour while maintaining the melting rate of the mixture at 0.70 hour, and an electrolyte melt for starting the electrolytic cell was prepared. The electrolyte melt with low hydrated magnesium chloride content obtained after electrolysis (the sum of the contents of potassium chloride and sodium chloride is 49wt.%, the solidification temperature is 587 ℃) is kept at 780 ℃, and 700g of the electrolyte melt is in surface contact with 200g of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite from the upper part (the adding amount of the electrolyte melt is 1.00 part by weight based on the adding amount of the mixture of the anhydrous magnesium chloride and the low-water ammonium carnalliteThe amount of the material was 3.50 parts by weight), the melting time of the solid material was kept at 0.80 hour. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the melt body at 0.09, heating to 760 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 10 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell is 0.002wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium is 0.006 wt.%.
Example 11
1000g of magnesium oxide and NH4Cl·MgCl2·6.0H2The mixture of O was mixed uniformly with 450g of ammonium chloride (0.45 parts by weight of ammonium chloride based on 1.00 parts by weight of the total amount of the charged magnesium chloride hydrate and ammonium carnallite hydrate) and distributed in the following manner: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 1.80, the porosity of the particle bed was 0.57, and the equivalent diameter of the channels in the particle bed was 0.63 mm. The above mixture of materials was heated at 640 ℃ for 0.9 hour (external heating, material edge to center temperature difference of 42 ℃), and a mixture of anhydrous magnesium chloride and low water ammonium carnallite was prepared. The anhydrous magnesium chloride content of the mixture was 11.40wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 4.60wt.% and 26.70wt.%, respectively. 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite 1000g of sodium chloride and potassium chloride were mixed uniformly (the total amount of the charged anhydrous magnesium chloride and low-water ammonium carnallite was 1.00 part by weight, the amount of the charged sodium chloride and potassium chloride was 5.00 parts by weight), the ratio of the height of the mixture to the maximum cross-sectional diameter was 0.95, the mixture was heated at 800 ℃ for 0.5 hour while maintaining the melting rate of the mixture for 1.8 hours, and an electrolyte melt for starting up the electrolytic cell was prepared. Keeping the electrolyte melt with low hydrated magnesium chloride content (the sum of the contents of potassium chloride and sodium chloride is 50wt.%, the solidification temperature is 590 ℃) obtained after electrolysis at 760 ℃, and mixing 800g of the electrolyte melt with 200g of anhydrous magnesium chloride and low anhydrous magnesium chloride from the upper partThe mixture of aqueous ammonium carnallite was brought into surface contact (the amount of the electrolyte melt was 4.00 parts by weight based on 1.00 part by weight of the amount of the mixture of anhydrous magnesium chloride and aqueous ammonium carnallite charged), and the melting time of the solid material was kept at 0.60 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the melt body at 0.16, heating to 760 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the magnesium metal.
The product obtained in example 11 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.07wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.02 wt.%.
Example 12
1000g of magnesium oxide and NH4Cl·MgCl2·1.8H2The mixture of O was mixed well with 5500g of ammonium chloride (5.50 parts by weight of ammonium chloride based on 1.00 part by weight of the total charged amount of magnesium chloride hydrate and ammonium carnallite hydrate) and distributed as follows: the ratio of the height of the material to the maximum cross-sectional diameter of the material in the mixture was 2.90, the porosity of the particle bed was 0.46, and the equivalent diameter of the channels in the particle bed was 0.37 mm. The above mixture of materials was heated at 620 ℃ for 0.6 hour (external heating, material edge to center temperature difference of 18 ℃) to prepare a mixture of anhydrous magnesium chloride and low water ammonium carnallite. The anhydrous magnesium chloride content of the mixture was 19.40wt.%, and the water and ammonium chloride content of the low water ammonium carnallite were 0.50wt.% and 24.30wt.%, respectively. 200g of the above mixture of anhydrous magnesium chloride and low-water ammonium carnallite 700g of sodium chloride and potassium chloride were mixed uniformly (the total amount of the charged anhydrous magnesium chloride and low-water ammonium carnallite was 1.00 part by weight, the amount of the charged sodium chloride and potassium chloride was 3.50 parts by weight), the ratio of the height of the mixture to the maximum cross-sectional diameter was 0.87, the mixture was heated at 790 ℃ for 1.0 hour while maintaining the melting rate of the mixture for 1.0 hour, and an electrolyte melt for starting up the electrolytic cell was prepared. The electrolyte melt (chloridization) with low hydrated magnesium chloride content obtained after electrolysisThe sum of the contents of potassium and sodium chloride was 58wt.%, the solidification temperature was 576 ℃) and the temperature was kept at 750 ℃ and 1000g of the electrolyte melt was brought into surface contact from the upper part with 200g of a mixture of anhydrous magnesium chloride and low-water ammonium carnallite (the charge amount of the electrolyte melt was 5.00 parts by weight based on 1.00 part by weight of the charge amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite) and the melting time of the solid matter was kept at 0.75 hours. And (3) keeping the ratio of the volume of the space above the obtained high-temperature melt to the melt body at 0.36, heating to 750 ℃, and preparing the electrolyte melt for continuously electrolyzing and producing the metal magnesium.
The product obtained in example 12 was characterized according to the measurement method described above. The results are as follows:
the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for starting the electrolytic cell was 0.04wt.%, and the mass ratio of magnesium oxide to anhydrous magnesium chloride in the prepared melt electrolyte for continuously electrolyzing metal magnesium was 0.01 wt.%.
Although the present invention is illustrated by the above examples to show the detailed process parameters and process flows of the present invention, the present invention is not limited to the above detailed process parameters and process flows, i.e., it is not meant that the present invention is necessarily dependent on the above detailed process parameters and process flows to be practiced. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.

Claims (9)

1. A continuous preparation method of molten salt electrolyte for electrolytic magnesium is characterized in that: the method comprises the following steps:
s1, uniformly mixing the magnesium-containing raw material with ammonium chloride to obtain a mixture of the magnesium-containing raw material and the ammonium chloride;
s2, distributing the mixture of the magnesium-containing raw material and ammonium chloride in a reactor according to the following conditions: the ratio of the height of the mixture material to the maximum cross section diameter of the material is 0.35-28.50, the porosity of a particle bed layer formed by the mixture is 0.26-0.70, and the equivalent diameter of a pore channel in the particle bed layer formed by the mixture is 0.01-1.50 mm; supplying heat to the solid material in radial direction by an external heat source, and ensuring that the temperature difference between the radial edge and the center is 12-75 ℃; heating the mixture at 350-590 ℃ for 0.1-5.5 hours to prepare a mixture of anhydrous magnesium chloride and low-water ammonium carnallite;
s3, uniformly mixing the mixture of the anhydrous magnesium chloride and the low-water ammonium carnallite with other metal chlorides, and ensuring that the ratio of the height of the uniformly mixed mixture to the maximum cross section diameter is 0.25-3.50; heating the uniformly mixed mixture at 500-880 ℃ for reaction for 0.2-4.0 hours, and controlling the melting time of the mixture to be 0.1-1.2 hours to prepare an electrolyte melt for starting the electrolytic cell;
s4, repeating the steps S1 and S2, heating the electrolyte melt with low anhydrous magnesium chloride content generated in the process of preparing the metal magnesium by electrolysis to 630-880 ℃, and adopting a surface contact mode with the anhydrous magnesium chloride and low-water ammonium carnallite mixture obtained in the step S2, wherein the ratio of the height of the mixture to the diameter of the contact surface is kept to be 0.10-6.50, and the melting time of the mixture is 0.10-3.85 hours; after the melting is finished, the melt is heated to 600-900 ℃, the ratio of the volume of the upper space of the high-temperature melt to the volume of the melt is kept between 0.01 and 0.95, and the melt containing anhydrous magnesium chloride is prepared by heating and is used as the electrolyte for continuously preparing the metal magnesium by electrolysis.
2. The continuous production method according to claim 1, characterized in that: in the step S1, the magnesium-containing raw material is selected from one of the group consisting of: magnesium chloride hydrate; magnesium oxide; ammonium carnallite hydrate; hydrated magnesium chloride and magnesium oxide; magnesium chloride hydrate and ammonium carnallite hydrate; magnesium oxide and ammonium hydroxide carnallite.
3. The continuous production method according to claim 2, characterized in that: when hydrated magnesium chloride is used as a raw material containing magnesium, the feeding amount of ammonium chloride is 0.02-2.00 parts by weight based on 1.00 part by weight of the feeding amount of the hydrated magnesium chloride; when magnesium oxide is used as a raw material containing magnesium, the feeding amount of ammonium chloride is 1.20-8.00 parts by weight based on 1.00 part by weight of the feeding amount of magnesium oxide; when ammonium hydroxide carnallite is used as the raw material containing magnesium, the feeding amount of ammonium chloride is 0.00-1.00 parts by weight based on 1.00 part by weight of the feeding amount of the ammonium hydroxide carnallite; when hydrated magnesium chloride and magnesium oxide are used as magnesium-containing raw materials, the feeding amount of ammonium chloride is 0.08 to 6.50 parts by weight based on 1.00 part by weight of the sum of the feeding amounts of the hydrated magnesium chloride and the magnesium oxide; when the magnesium chloride hydrate and the ammonium hydroxide carnallite are used as magnesium-containing raw materials, the feeding amount of the ammonium chloride is 0.00-1.25 parts by weight based on the total feeding amount of the magnesium chloride hydrate and the ammonium hydroxide carnallite being 1.00 part by weight; when magnesium oxide and ammonium hydroxide carnallite are used as raw materials containing magnesium, the feeding amount of ammonium chloride is 0.45-5.50 parts by weight based on the total feeding amount of the magnesium oxide and the ammonium hydroxide carnallite being 1.00 part by weight.
4. The continuous production method according to claim 1, characterized in that: in the step S2, the anhydrous magnesium chloride is present in an amount of 10.00 to 75.00wt.% in the mixture of anhydrous magnesium chloride and low-water ammonium carnallite; the low water ammonium carnallite has a water content of less than 10.5wt.%, and the low water ammonium carnallite has an ammonium chloride content of 3.5-35.5 wt.%.
5. The continuous production method according to claim 1, characterized in that: in the step S3, the amount of the other metal chloride is 1.50 to 9.00 parts by weight based on 1.00 part by weight of the total amount of the mixture of anhydrous magnesium chloride and low-water ammonium carnallite charged.
6. The continuous production method according to claim 1, characterized in that: in the step S3, the other metal chloride is one selected from the group consisting of: sodium chloride; potassium chloride; sodium chloride and potassium chloride; sodium chloride, potassium chloride and calcium chloride; sodium chloride, potassium chloride, calcium chloride and barium chloride.
7. The continuous production method according to claim 1, characterized in that: in the step S4, the electrolyte melt with low anhydrous magnesium chloride content generated in the process of preparing the metal magnesium by electrolysis has the sum of the contents of potassium chloride and sodium chloride of 42-80wt.% and the solidification temperature of the electrolyte melt of 450-650 ℃ as the raw material for continuously preparing the electrolyte melt.
8. The continuous production method according to claim 1, characterized in that: in the step S4, the amount of the electrolyte melt having a low anhydrous magnesium chloride content is 2.20 to 6.80 parts by weight based on 1.00 part by weight of the amount of the mixture of anhydrous magnesium chloride and low water ammonium carnallite charged.
9. The continuous production method according to claim 1, characterized in that: in step S4, the ammonium chloride released during the continuous production process is recovered and returned to step S1 for reuse.
CN202110383198.6A 2021-04-09 2021-04-09 Continuous preparation method of molten salt electrolyte for electrolytic magnesium Active CN113104870B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202110383198.6A CN113104870B (en) 2021-04-09 2021-04-09 Continuous preparation method of molten salt electrolyte for electrolytic magnesium

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202110383198.6A CN113104870B (en) 2021-04-09 2021-04-09 Continuous preparation method of molten salt electrolyte for electrolytic magnesium

Publications (2)

Publication Number Publication Date
CN113104870A CN113104870A (en) 2021-07-13
CN113104870B true CN113104870B (en) 2022-06-03

Family

ID=76715035

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202110383198.6A Active CN113104870B (en) 2021-04-09 2021-04-09 Continuous preparation method of molten salt electrolyte for electrolytic magnesium

Country Status (1)

Country Link
CN (1) CN113104870B (en)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102491384B (en) * 2011-12-01 2013-10-16 中国科学院过程工程研究所 Method for preparing anhydrous magnesium chloride by utilizing magnesium chloride hexahydrate
CN102491382B (en) * 2011-12-01 2013-10-16 中国科学院过程工程研究所 Method for preparing anhydrous magnesium chloride by utilizing ammonium camallite

Also Published As

Publication number Publication date
CN113104870A (en) 2021-07-13

Similar Documents

Publication Publication Date Title
KR102413985B1 (en) Hydrometallurgical process to produce pure magnesium metal and various by-products
AU2014383725B2 (en) Method for directly recovering lead oxide used for a lead-acid battery cathode from waste lead paste
CN103911514B (en) The recovery and treatment method of scrap hard alloy grinding material
CN106611841A (en) Method for preparing nickel-cobalt-manganese ternary material precursor by using nickel-cobalt slag material
CN114031099B (en) Acidification roasting method for efficiently treating aluminum electrolysis solid waste
CN113501536A (en) Method for preparing aluminum fluoride product by multi-waste combined treatment and aluminum fluoride product
CN104418370A (en) Method and device for preparing anhydrous magnesium chloride
CN109264748B (en) Method for preparing lithium carbonate from crude lithium phosphate
CN108751234B (en) Method for purifying lithium fluoride
CN109599602A (en) The method that the waste and old positive electrode of a kind of pair of lithium battery carries out resource utilization
CN113104870B (en) Continuous preparation method of molten salt electrolyte for electrolytic magnesium
CN115196609B (en) Method for recovering iron phosphate from lithium iron phosphate lithium extraction slag and application thereof
CN110562946A (en) Battery-grade anhydrous iron phosphate with sheet structure and preparation method thereof
CN113151680B (en) Method for recycling waste lithium batteries
CN113697834A (en) Method for preparing Friedel salt by extracting titanium slag and Friedel salt
CN111153395B (en) Method for comprehensively recovering fluorine and carbon powder in electrolytic aluminum cathode carbon block
CN117327923B (en) Method for jointly extracting lithium from waste aluminum electrolyte and overhaul slag
JPS6256215B2 (en)
US3980536A (en) Process for producing magnesium metal from magnesium chloride brines
CN112899728B (en) Ammonium carnallite dehydration material and method for preparing magnesium electrolyte melt by using same
CN115161478B (en) By MgO/SiO in minerals containing Si and Mg2Method for extracting magnesium metal through carbon in-situ high-temperature reduction reaction
CN116835626A (en) Method for comprehensively utilizing fluorogypsum and aluminum electrolyte
CN118343706A (en) Method for preparing lithium phosphate from waste lithium iron phosphate lithium extraction waste residues
CN117098862A (en) Method for integrally recycling lithium through full chain
CN118047365A (en) Recovery treatment method of aluminum electrolysis waste cathode

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant