Method for extracting lithium by roasting aluminum electrolyte waste residue with assistance of sulfuric acid and sulfate

Abstract

The invention relates to the technical field of lithium extraction, in particular to a method for extracting lithium by roasting aluminum electrolyte waste residues with the assistance of sulfuric acid and sulfate jointly, which comprises the following steps: pretreating initial blocky aluminum electrolyte waste residues to obtain raw material fine powder; adding calcium sulfate into the raw material fine powder according to a preset proportion, and grinding to obtain a mixed material; putting the mixed material and concentrated sulfuric acid into a beaker, mixing and stirring, and roasting to obtain a roasted material; the roasted material is subjected to ball milling and then subjected to water leaching according to a preset liquid-solid-liquid ratio, and a lithium sulfate leaching solution is obtained; and adding lithium equivalent sodium phosphate into the heated lithium sulfate leaching solution to react and precipitate lithium. Lithium is roasted into lithium sulfate, the lithium sulfate is soaked in water and enters a solution, finally the lithium is recycled in a lithium phosphate form, a part of HF waste gas is fixed in a CaF2 form in an initial reaction, the waste gas treatment pressure is reduced, and the final lithium leaching rate is larger than 95%. Therefore, the problem that an existing method for extracting lithium from aluminum electrolyte waste residues is low in recovery rate is solved.

Description

Technical Field

[0001] The invention relates to the technical field of lithium extraction, and in particular to a method for extracting lithium by roasting aluminum electrolyte waste slag with the aid of sulfuric acid and sulfate. Background Art

[0002] Waste aluminum electrolyte is a complex solid waste, mainly composed of cryolite (including Na3AlF6, K2NaAlF6, Na2LiAlF6, etc.), fluorite (CaF2) and carbon black. With the increasing shortage of lithium resources and the increasingly serious environmental pollution caused by the storage of waste aluminum electrolytes, how to efficiently and environmentally friendly recover the valuable elements in waste aluminum electrolytes, especially lithium, has become a hot topic of current research. Traditional treatment methods often have problems such as low efficiency and severe environmental pollution, and cannot meet the current dual needs of efficient resource utilization and environmental protection.

[0003] In recent years, researchers have begun to explore the use of chemical methods to treat waste aluminum electrolytes in order to achieve efficient recovery of valuable elements such as lithium and solidification of harmful fluorides. However, most existing chemical treatment methods have problems such as harsh reaction conditions, high energy consumption, and low recovery efficiency, which limits their application in actual industry. Summary of the invention

[0004] The purpose of the present invention is to provide a method for extracting lithium from aluminum electrolyte waste slag by co-assisted roasting of sulfuric acid and sulfate, aiming to solve the problem of low recovery rate of existing methods for extracting lithium from aluminum electrolyte waste slag.

[0005] To achieve the above object, the present invention provides a method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate, comprising the following steps:

[0006] Pre-treating the initial bulk aluminum electrolyte waste slag to obtain raw material fine powder;

[0007] Adding calcium sulfate to the raw material fine powder according to a preset ratio and grinding them to obtain a mixed material;

[0008] The mixed material and concentrated sulfuric acid are placed in a beaker, mixed and stirred, and then roasted to obtain a roasted material;

[0009] After ball milling the calcined material, water leaching is performed according to a preset liquid-solid-liquid ratio to obtain a lithium sulfate leaching solution;

[0010] Add lithium equivalent sodium phosphate to the heated lithium sulfate leaching solution to react and precipitate lithium.

[0011] Among them, in “pre-treating the initial bulk aluminum electrolyte waste slag to obtain raw material fine powder”, it includes:

[0012] Crushing the initial bulk aluminum electrolyte waste slag;

[0013] The crushed initial bulk aluminum electrolyte waste slag is sieved to obtain raw material fine powder, and quantitative analysis is performed.

[0014] Among them, in “adding calcium sulfate to the raw material fine powder according to a preset ratio and grinding to obtain a mixture”, the preset ratio is 1 to 1.5:1.

[0015] Among them, in “putting the mixed material and concentrated sulfuric acid into a beaker, mixing and stirring, and then roasting to obtain a roasted material”, the roasting temperature is 300° C.-500° C., and the time is 2h-3h.

[0016] Among them, in “ball-milling the roasted material and then immersing it in water according to a preset liquid-to-liquid ratio to obtain a lithium sulfate leaching solution”, the preset solid-liquid ratio is 2-4:1, and the immersion time is 0.5h-2h.

[0017] Wherein, in “adding lithium equivalent sodium phosphate to the heated lithium sulfate leaching solution to react and precipitate lithium”, the heating temperature of the lithium sulfate leaching solution is 90° C.; and the lithium precipitation time is 2 hours.

[0018] The method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate comprises the following steps: pre-treating the initial blocky aluminum electrolyte waste slag to obtain raw material fine powder; adding calcium sulfate to the raw material fine powder according to a preset ratio for grinding to obtain a mixed material; putting the mixed material and concentrated sulfuric acid into a beaker for mixing and stirring, and then roasting to obtain a roasted material; ball-milling the roasted material and then immersing it in water according to a preset liquid-to-solid ratio to obtain a lithium sulfate leaching solution; adding lithium equivalent sodium phosphate to the heated lithium sulfate leaching solution to react and precipitate lithium. The main reaction equations of the present invention are: 2Na2LiAlF6+CaSO4+5H2SO4=Na2SO4+Li2SO4+Al2(SO4)3+CaF2+10HF, 3Li2SO4+2Na3PO4=2Li3PO4+3Na2SO4, lithium is calcined to become lithium sulfate and leached into the solution, and finally lithium is recovered in the form of lithium phosphate, a part of HF waste gas is fixed in the form of CaF2 in the initial reaction, reducing the waste gas treatment pressure, and finally the lithium leaching rate is greater than 95%. Thus, the problem of low recovery rate of the existing method for extracting lithium from aluminum electrolyte waste slag is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 This is a schematic diagram of lithium extraction.

[0021] Figure 2 The present invention provides a flow chart of a method for extracting lithium by using sulfuric acid and sulfate to assist in roasting aluminum electrolyte waste slag.

[0022] Figure 3 The present invention is a flow chart of pretreating the initial bulk aluminum electrolyte waste slag to obtain raw material fine powder. DETAILED DESCRIPTION

[0023] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0024] See also Figures 1 to 3 The present invention provides a method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate, comprising the following steps:

[0025] S1 pre-treats the initial bulk aluminum electrolyte waste slag to obtain raw material fine powder;

[0026] S11 crushes the initial bulk aluminum electrolyte waste slag;

[0027] Specifically, the initial bulk aluminum electrolyte waste slag is crushed by a crusher.

[0028] S12 sieves the crushed initial bulk aluminum electrolyte waste slag to obtain raw material fine powder, and performs quantitative analysis.

[0029] Specifically, the crushed initial bulk aluminum electrolyte waste slag is sieved through a 120-mesh sieve, and the sieve material is taken to detect the content of each component of the raw material fine powder.

[0030] S2 adding calcium sulfate to the raw material fine powder according to a preset ratio and grinding to obtain a mixed material;

[0031] The preset ratio is 1 to 1.5:1.

[0032] Specifically, the crushed raw material fine powder is added with calcium sulfate according to the molar ratio of n(CaSO4):n(2Li)=1-1.5:1, and the mixture is ground and mixed.

[0033] S3: putting the mixed material and concentrated sulfuric acid into a beaker, mixing and stirring, and then roasting to obtain a roasted material;

[0034] The calcination temperature is 300° C.-500° C., and the calcination time is 2 h-3 h.

[0035] Specifically, the primary mixed material is placed in a beaker, and concentrated sulfuric acid with a mass ratio of 40% to 70% is added and stirred evenly, and the material to be calcined is placed in a corundum ark and placed in a muffle furnace, and calcined at 300 to 500° C. for 2 to 3 hours.

[0036] S4 ball-mills the calcined material and then leaches it in water according to a preset liquid-solid-liquid ratio to obtain a lithium sulfate leaching solution;

[0037] The preset solid-liquid ratio is 2-4:1, and the immersion time is 0.5h-2h.

[0038] Specifically, the calcined material is ball-milled, and soaked in water at room temperature for 0.5 to 2 hours at a liquid-to-solid ratio of 2 to 4:1 to obtain a lithium sulfate leaching solution.

[0039] S5: Add lithium equivalent sodium phosphate to the heated lithium sulfate leaching solution to react and precipitate lithium.

[0040] The heating temperature of the lithium sulfate leaching solution is 90° C. and the lithium precipitation time is 2 hours.

[0041] Specifically, the leaching solution is heated to 90° C., and lithium equivalent sodium phosphate is added to react for 2 hours to precipitate lithium. The lithium recovery rate in the entire recovery process is greater than 95%.

[0042] Example 1

[0043] Raw materials: Aluminum electrolyte waste slag is crushed and screened to obtain the raw material fine powder used in the embodiment of the present invention, and its element quantitative analysis is as follows:

[0044]

[0045] Initial mixing: Add calcium sulfate to the crushed raw material fine powder according to the molar ratio of n(CaSO4):n(2Li)=1:1, and grind and mix.

[0046] Mixing + calcining: Place the primary mixed material in a beaker and add 50% of its mass of concentrated sulfuric acid and stir evenly. Use a corundum ark to hold the material to be calcined and place it in a muffle furnace and calcine at 400°C for 2 hours.

[0047] Ball milling + water leaching: ball mill the calcined material and soak it in water at room temperature for 0.5h at a liquid-to-solid ratio of 4:1 to obtain a lithium sulfate leaching solution.

[0048] Lithium precipitation: The leaching solution was heated to 90°C, and lithium equivalent sodium phosphate was added to react for 2 hours to precipitate lithium. The lithium recovery rate in the entire recovery process was 95.56%.

[0049] Example 2

[0050] Initial mixing: Add calcium sulfate to the crushed raw material fine powder according to the molar ratio of n(CaSO4):n(2Li)=1:1, and grind and mix.

[0051] Mixing + calcining: Place the primary mixed material in a beaker and add 60% of its mass of concentrated sulfuric acid and stir evenly. Use a corundum ark to hold the material to be calcined and place it in a muffle furnace and calcine at 400°C for 2 hours.

[0052] Ball milling + water leaching: ball mill the calcined material and soak it in water at room temperature for 0.5h at a liquid-to-solid ratio of 3:1 to obtain a lithium sulfate leaching solution.

[0053] Lithium precipitation: The leaching solution was heated to 90°C, and lithium equivalent sodium phosphate was added to react for 2 hours to precipitate lithium. The lithium recovery rate in the entire recovery process was 96.02%.

[0054] Example 3

[0055] Initial mixing: Add calcium sulfate to the crushed raw material fine powder according to the molar ratio of n(CaSO4):n(2Li)=1:1, and grind and mix.

[0056] Mixing + calcining: Place the primary mixed material in a beaker and add 70% of its mass of concentrated sulfuric acid and stir evenly. Use a corundum ark to hold the material to be calcined and place it in a muffle furnace and calcine at 400°C for 2 hours.

[0057] Ball milling + water leaching: ball mill the calcined material and soak it in water at room temperature for 0.5h at a liquid-to-solid ratio of 2:1 to obtain a lithium sulfate leaching solution.

[0058] Lithium precipitation: The leaching solution was heated to 90°C, and lithium equivalent sodium phosphate was added to react for 2 hours to precipitate lithium. The lithium recovery rate in the entire recovery process was 95.13%.

[0059] The above disclosure is only a preferred embodiment of the method for extracting lithium from aluminum electrolyte waste slag by co-assisted roasting with sulfuric acid and sulfate of the present invention. Of course, it cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate, characterized in that: The following steps are involved: Pre-treating the initial bulk aluminum electrolyte waste slag to obtain raw material fine powder; Adding calcium sulfate to the raw material fine powder according to a preset ratio and grinding them to obtain a mixed material; The mixed material and concentrated sulfuric acid are placed in a beaker, mixed and stirred, and then roasted to obtain a roasted material; After ball milling the calcined material, water leaching is performed according to a preset liquid-solid-liquid ratio to obtain a lithium sulfate leaching solution; Add lithium equivalent sodium phosphate to the heated lithium sulfate leaching solution to react and precipitate lithium.

2. The method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate as claimed in claim 1, characterized in that: In "pre-treating the initial bulk aluminum electrolyte waste slag to obtain raw material fine powder", it includes: Crushing the initial bulk aluminum electrolyte waste slag; The crushed initial bulk aluminum electrolyte waste slag is sieved to obtain raw material fine powder, and quantitative analysis is performed.

3. The method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate as claimed in claim 1, characterized in that: In “adding calcium sulfate to the raw material fine powder in a preset ratio and grinding them to obtain a mixed material”, the preset ratio is 1 to 1.5:

1.

4. The method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate as claimed in claim 1, characterized in that: In "putting the mixed material and concentrated sulfuric acid into a beaker, mixing and stirring, and then roasting to obtain a roasted material", the roasting temperature is 300° C.-500° C., and the time is 2 h-3 h.

5. The method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate as claimed in claim 1, characterized in that: In “ball milling the calcined material and then immersing it in water according to a preset liquid-to-solid ratio to obtain a lithium sulfate leaching solution”, the preset solid-to-liquid ratio is 2-4:1, and the immersion time is 0.5h-2h.

6. The method for extracting lithium by roasting aluminum electrolyte waste slag with sulfuric acid and sulfate as claimed in claim 1, characterized in that: In "adding lithium equivalent sodium phosphate to the heated lithium sulfate leaching solution to react and precipitate lithium", the heating temperature of the lithium sulfate leaching solution is 90° C. and the lithium precipitation time is 2 hours.

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