Search

CN-122013260-A - Preparation method of magnesium-lithium alloy based on ammonia dehydration and fused salt electrolysis coupling and magnesium-lithium alloy

CN122013260ACN 122013260 ACN122013260 ACN 122013260ACN-122013260-A

Abstract

The invention discloses a magnesium-lithium alloy preparation method based on ammonia dehydration and fused salt electrolysis coupling, which comprises the steps of placing bischofite and lithium chloride in a dehydration tank of an integrated reactor, carrying out ammonia dehydration for 0.5-4h at 180-300 ℃ to obtain a solid material, conveying the solid material to a fused salt electrolysis tank of the integrated reactor, introducing direct current at 450-550 ℃ to carry out electrolysis treatment, and carrying out cathodic co-electrodeposition to prepare the magnesium-lithium alloy. The stable ammine ion cluster is formed, so that the physical and chemical properties of the electrolyte are optimized, side reactions are inhibited, the current efficiency is improved, the precise control of the metallographic composition and microstructure is realized, and the high-performance and high-purity magnesium-lithium alloy is directly obtained. Solves the problems of dependence on an inert gas protection system, fragmentation of the process flow, difficult dehydration and low alloy purity in the prior art.

Inventors

  • QIAN ZHIQIANG
  • YE XIUSHEN
  • MU TONG
  • LI KEXIN
  • HAN WENJIE
  • LI MINGZHEN

Assignees

  • 中国科学院青海盐湖研究所

Dates

Publication Date
20260512
Application Date
20260119

Claims (10)

  1. 1. The preparation method of the magnesium-lithium alloy based on the coupling of ammonia dehydration and molten salt electrolysis is characterized by comprising the following steps: s1, placing bischofite and lithium chloride in a dehydration tank of an integrated reactor, and dehydrating for 0.5-4 hours at 180-300 ℃ by an ammonia method to obtain a solid material; s2, conveying the solid materials to a fused salt electrolysis tank of the integrated reactor, introducing direct current at 450-550 ℃ for electrolytic treatment, and preparing the magnesium-lithium alloy by cathodic co-electrodeposition.
  2. 2. The method for preparing the magnesium-lithium alloy based on ammonia dehydration and fused salt electrolysis coupling according to claim 1, wherein bischofite and lithium chloride are subjected to ammonia dehydration at 180-300 ℃ for 0.5-4 hours, specifically, after the bischofite and the lithium chloride are mixed, the bischofite and the lithium chloride are subjected to ammonia dehydration at 180-300 ℃ for 0.5-4 hours, or the bischofite and the lithium chloride are respectively subjected to ammonia dehydration at 180-300 ℃ for 0.5-4 hours and then mixed; The ammonia dehydration can be carried out by introducing bischofite and lithium chloride into dry pure ammonia gas or mixed gas of ammonia gas and inert gas, or adding ammonium chloride solid into bischofite and lithium chloride, and fully grinding and mixing.
  3. 3. The method for preparing the magnesium-lithium alloy based on the coupling of ammonia dehydration and molten salt electrolysis according to claim 1, wherein in the step S1, the molar ratio of magnesium to lithium in bischofite and lithium chloride is 5-15:1.
  4. 4. The method for preparing the magnesium-lithium alloy based on coupling of ammonia dehydration and molten salt electrolysis according to claim 1, wherein in the step S2, the anode of the molten salt electrolysis tank is selected from one of graphite, metal oxide ceramic or metal ceramic.
  5. 5. The method for preparing the magnesium-lithium alloy based on the coupling of ammonia dehydration and molten salt electrolysis according to claim 1, wherein in the step S2, the cathode of the molten salt electrolysis bath is selected from one of low-melting-point magnesium-lithium alloy, solid magnesium, tin, molybdenum, copper, stainless steel, tungsten and nickel.
  6. 6. The method for preparing a magnesium-lithium alloy based on coupling of ammonia dehydration and molten salt electrolysis according to claim 5, wherein in the step S2, the cathode of the molten salt electrolysis bath is selected from solid magnesium or molybdenum.
  7. 7. The method for preparing the magnesium-lithium alloy based on the coupling of ammonia dehydration and molten salt electrolysis according to claim 1, wherein in the step S2, the cathode current density is controlled to be 0.5-2.5A/cm 2 in the electrolysis treatment.
  8. 8. The method for preparing the magnesium-lithium alloy based on the coupling of ammonia dehydration and molten salt electrolysis according to claim 1, wherein in the step S2, organic amine is used as a coupling agent, one or more of KCl, naCl, csCl, rbCl and fluoride salts are used as a cosolvent, and Mg (BH 4 ) 2 is used as an overpotential reducing agent for magnesium deposition).
  9. 9. A magnesium-lithium alloy, characterized in that it is prepared by the preparation method according to any one of the preceding claims 1-8.
  10. 10. A magnesium-lithium alloy according to claim 9, which is an alpha-phase, beta-phase or alpha + beta dual-phase magnesium-lithium alloy having a lithium content of 5-16wt%.

Description

Preparation method of magnesium-lithium alloy based on ammonia dehydration and fused salt electrolysis coupling and magnesium-lithium alloy Technical Field The invention relates to the technical field of landfill leachate treatment, in particular to a magnesium-lithium alloy preparation method based on ammonia dehydration and fused salt electrolysis coupling and a magnesium-lithium alloy. Background The magnesium-lithium alloy is the lightest metal structural material in the world, and has irreplaceable application prospect in the fields of aerospace, military equipment, 3C electronic products and the like due to excellent specific strength, specific rigidity and good damping and shock absorption performance. At present, the industrialized production of magnesium-lithium alloy mainly adopts a 'counter doping method'. The process comprises the steps of firstly producing magnesium metal by a Pidgeon method or an electrolysis method, producing lithium metal by a molten salt electrolysis method, and then carrying out melt blending, stirring and casting on two metals in a crucible under the protection of high temperature (generally higher than 700 ℃) vacuum or inert atmosphere. The molten salt electrolysis process is regarded as a potential alternative process, and can directly prepare alloy from salt in one step, taking anhydrous magnesium chloride and anhydrous lithium chloride which are dehydrated thoroughly in advance as raw materials, mixing the raw materials according to a required proportion, placing the raw materials in a closed electrolysis tank, heating the raw materials to 650-750 ℃ under the protection of inert gas (such as argon) to enable the raw materials to be melted to form electrolyte, then introducing direct current, and separating out magnesium-lithium alloy at a cathode. In theory, the flow is shorter and the energy consumption is lower, but the key bottleneck of the scheme is that anhydrous magnesium chloride is the precondition of the scheme, the obtained electrolytic anhydrous magnesium chloride is the basic stone of the whole process, and the cost and the difficulty of the step are extremely high. The protective atmosphere is a necessary condition, in order to prevent the damage of moisture and oxygen in the air to molten salt and metal products, the air must be isolated in the whole process, and the whole electrolysis system must be operated under the protection of inert atmosphere, so that the operability of equipment is limited, and the maintenance cost and the energy consumption are increased. The traditional thermal dehydration path can not radically stop the hydrolysis reaction of magnesium chloride, and the introduced MgO impurity reduces the current efficiency and affects the purity of the alloy. Disclosure of Invention In view of the defects of the prior art, the invention aims to provide a magnesium-lithium alloy preparation method based on ammonia dehydration and fused salt electrolysis coupling, which solves the problems of dependence on an inert gas protection system, fragmentation of a process flow, difficult dehydration and low alloy purity in the prior art. The invention provides a magnesium-lithium alloy preparation method based on ammonia dehydration and fused salt electrolysis coupling, which comprises the following steps: s1, placing bischofite and lithium chloride in a dehydration tank of an integrated reactor, and dehydrating for 0.5-4 hours at 180-300 ℃ by an ammonia method to obtain a solid material; s2, conveying the solid materials to a fused salt electrolysis tank of the integrated reactor, introducing direct current at 450-550 ℃ for electrolytic treatment, and preparing the magnesium-lithium alloy by cathodic co-electrodeposition. The integrated reactor comprises a dehydration tank and a molten salt electrolytic tank, and can be of an up-down structure or a parallel structure, and the dehydration tank and the electrolytic tank are connected through a screw conveyor or pneumatic conveying. The electrolytic tank adopts a multi-stage tank or a bipolar electrode tank. Preferably, the bischofite and the lithium chloride are dehydrated for 0.5 to 4 hours in an ammonia method at 180 to 300 ℃, specifically, the bischofite and the lithium chloride are mixed and dehydrated for 0.5 to 4 hours in an ammonia method at 180 to 300 ℃, or the bischofite and the lithium chloride are respectively dehydrated for 0.5 to 4 hours in an ammonia method at 180 to 300 ℃ and then are mixed. The ammonia dehydration can be carried out by introducing bischofite and lithium chloride into dry pure ammonia gas or mixed gas of ammonia gas and inert gas, or adding ammonium chloride solid into bischofite and lithium chloride, fully grinding and mixing, decomposing ammonium chloride under heating to generate NH 3 and HCl, and further enhancing hydrolysis inhibition effect by micro-HCl. Preferably, in the step S1, the molar ratio of magnesium to lithium in bischofite to lithium chloride is 5-15:1.