Comprehensive recovery method of lithium-aluminum-silicon-boron-magnesium glass

Abstract

The invention provides a comprehensive recovery method of lithium-aluminum-silicon-boron-magnesium glass, which comprises the following steps: (1) crushing waste lithium-aluminum-silicon-boron-magnesium glass, slurrying, heating and carrying out acid leaching treatment to obtain silicon slag and an acid leaching solution, and carrying out membrane separation and concentration treatment on the acid leaching solution to obtain a concentrated solution; performing solid-liquid separation to obtain a lithium-boron-containing fresh water solution and an aluminum-magnesium-containing concentrated water solution; (2) mixing the lithium-boron-containing fresh water solution with a phosphorus source to carry out lithium precipitation reaction, carrying out solid-liquid separation to obtain lithium precipitation mother liquor and lithium phosphate, mixing the lithium precipitation mother liquor with a magnesium source to carry out boron precipitation reaction, and carrying out solid-liquid separation to obtain magnesium borate and wastewater; and (3) carrying out concentration crystallization treatment on the concentrated aqueous solution containing aluminum and magnesium to obtain aluminum salt crystals and crystallization mother liquor, carrying out magnesium precipitation treatment on the crystallization mother liquor, and carrying out solid-liquid separation to obtain magnesium hydroxide. According to the method disclosed by the invention, efficient and comprehensive recovery of metal elements in the lithium aluminum silicon boron magnesium glass is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of resource recovery and relates to a comprehensive recovery method of lithium aluminum silicon boron magnesium glass. Background Art

[0002] Lithium aluminum borosilicate magnesium glass is a versatile specialty glass. Its typical composition includes SiO2 (50-70%) as the glass network skeleton, Al2O3 (10-20%) to enhance chemical stability, Li2O (5-15%) as a flux and conductive component, B2O3 (5-15%) to lower the melting point and adjust the thermal expansion coefficient, and a small amount of MgO (1-5%) to improve mechanical strength and thermal shock resistance. Through the synergistic effect of its components, this glass system combines a low melting point with high chemical stability, excellent thermal properties, and ionic conductivity. It is widely used in lithium battery separators, high-temperature optical glass, and specialty packaging materials.

[0003] CN118813959A discloses a method for recovering valuable elements in lithium-containing glass waste, comprising the following steps: acid leaching the lithium-containing glass waste to obtain a leachate and a leach residue; mixing the leachate with an alum-forming agent to perform a first-stage aluminum removal to obtain a crude alum product and a first-stage aluminum-removed liquid; adjusting the pH value of the first-stage aluminum-removed liquid to 2-3.5, then mixing it with a precipitant to perform a second-stage aluminum removal to obtain a second-stage aluminum-removed liquid; mixing the second-stage aluminum-removed liquid with an oxidant, then adjusting the pH value to 10-13 to remove impurities to obtain a de-impurity liquid; and preparing a lithium-containing compound using the de-impurity liquid to complete the recovery of valuable elements in the lithium-containing glass waste.

[0004] CN118255360A discloses a method for selectively separating and recovering boron from boron-containing aluminosilicate glass, the method comprising the following steps: (1) ball-milling the boron-containing aluminosilicate glass, calcining it, adding water to slurry it, mixing the slurried material with sulfuric acid, and subjecting it to pressurized acid leaching to obtain a boron-containing leachate; (2) adjusting the pH of the boron-containing leachate, adding sodium carbonate to precipitate magnesium, and obtaining a sodium borate solution; and (3) concentrating and crystallizing the sodium borate solution to obtain borax.

[0005] The above scheme has poor recovery effect on various metal elements, and it is difficult to achieve comprehensive recovery of various metals, and the actual application effect is poor. Summary of the Invention

[0006] The object of the present invention is to provide a comprehensive recovery method for lithium aluminum silicate boro magnesium glass. The present invention uses a membrane separation process to pre-separate a complex leachate to obtain lithium boron fresh water and aluminum magnesium concentrated water, while significantly improving the lithium recovery rate. At the same time, the aluminum salt product is recovered by evaporation-crystallization, and the magnesium oxide prepared by magnesium precipitation-pyrolysis is reused in the concentrated water lithium precipitation mother liquor to prepare the magnesium borate by-product, thereby realizing the efficient and comprehensive recovery of metal elements in lithium aluminum silicate boro magnesium glass.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a comprehensive recovery method for lithium aluminum silicon boro magnesium glass, the comprehensive recovery method comprising the following steps:

[0009] (1) crushing waste lithium aluminum borosilicate magnesium glass into pulp, subjecting it to heated acid leaching treatment to obtain silicon slag and acid leaching solution, and subjecting the acid leaching solution to membrane separation and concentration treatment, and performing solid-liquid separation to obtain a lithium-boron-containing fresh water solution and an aluminum-magnesium-containing concentrated water solution;

[0010] (2) mixing the lithium-boron-containing freshwater solution with a phosphorus source to carry out lithium precipitation reaction, and performing solid-liquid separation to obtain a lithium precipitation mother liquor and lithium phosphate, and mixing the lithium precipitation mother liquor with a magnesium source to carry out boron precipitation reaction, and obtaining magnesium borate and wastewater through solid-liquid separation;

[0011] (3) The aluminum-magnesium concentrated aqueous solution is concentrated and crystallized to obtain aluminum salt crystals and a crystallization mother liquor, and the crystallization mother liquor is subjected to magnesium precipitation treatment, and solid-liquid separation is performed to obtain magnesium hydroxide.

[0012] The present invention does not limit the order of operations of step (2) and step (3), and step (2) or step (3) can be performed first.

[0013] The present invention uses a membrane separation process to concentrate and separate the acid leachate of lithium-aluminum-silicon-boro-magnesium glass, producing a lithium-boron-containing freshwater solution and an aluminum-magnesium-containing concentrated aqueous solution. The two solutions are then subjected to precipitation treatment, achieving highly selective separation of the high-value elements lithium and boron from aluminum and magnesium. This effectively avoids the lithium carryover / adsorption loss problem associated with traditional lithium-aluminum separation processes and promotes diversified processing methods for elements such as aluminum and magnesium. After membrane concentration, lithium and boron are selectively separated from the lithium-boron-containing freshwater solution by precipitating lithium phosphate. The aluminum-magnesium-containing concentrated aqueous solution undergoes evaporative concentration followed by cooling and crystallization to separate the majority of the aluminum. The remaining magnesium-aluminum mixture is then precipitated by adjusting the base to produce magnesium hydroxide.

[0014] Preferably, the median particle size D50 of the waste lithium aluminum borosilicate magnesium glass after pulverization in step (1) is less than 100 μm.

[0015] Preferably, the solvent for the slurrying in step (1) comprises water.

[0016] Preferably, the liquid-to-solid mass ratio of the slurry in step (1) is (2.8-10):1, for example: 2.8:1, 3:1, 5:1, 8:1 or 10:1, etc., and is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the acid solution used in the heated acid leaching treatment in step (1) includes a sulfuric acid solution.

[0018] Preferably, the acid-ore ratio of the heated acid leaching treatment in step (1) is (1-1.3):1, for example: 1:1, 1.05:1, 1.1:1, 1.2:1 or 1.3:1, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0019] Preferably, the temperature of the heating acid leaching treatment in step (1) is 80°C to 95°C, for example, 80°C, 82°C, 85°C, 90°C or 95°C, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0020] Preferably, the time for the heating acid leaching treatment in step (1) is 2 hours to 6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours or 6 hours, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0021] Preferably, the membrane separation and concentration treatment in step (1) comprises separating the acid solution using a nanofiltration membrane and then concentrating it using an RO membrane.

[0022] Preferably, after the RO membrane is concentrated, the lithium content of the obtained lithium-boron-containing freshwater solution is 8 g / L to 20 g / L, for example, 8 g / L, 10 g / L, 12 g / L, 15 g / L or 20 g / L.

[0023] Preferably, the phosphorus source in step (2) includes phosphoric acid.

[0024] Preferably, the molar ratio of phosphorus in the phosphorus source to lithium in the lithium-boron-containing freshwater solution in step (2) is (1-1.2):3, for example: 1:3, 1.05:3, 1.1:3, 1.15:3 or 1.2:3, etc., and is not limited to the listed values. Other values ​​not listed within this numerical range are also applicable.

[0025] Preferably, the pH of the lithium precipitation reaction in step (2) is 10-11, for example, 10, 10.2, 10.5, 10.8 or 11, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0026] Preferably, the temperature of the lithium precipitation reaction in step (2) is 75°C to 90°C, for example: 75°C, 78°C, 80°C, 85°C, 88°C or 90°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0027] Preferably, the magnesium source in step (2) comprises magnesium oxide.

[0028] Preferably, the molar ratio of the magnesium element in the magnesium source in step (2) to the boron element in the lithium precipitation mother liquor is (1.5 to 3):1, for example: 1.5:1, 1.8:1, 2:1, 2.5:1 or 3:1, etc., is not limited to the listed values, and other unlisted values ​​within this numerical range are also applicable.

[0029] Preferably, the pH of the boron precipitation reaction in step (2) is 9.5 to 10.5, for example, 9.5, 9.8, 10, 10.2 or 10.5, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0030] Preferably, the temperature of the boron precipitation reaction in step (2) is 60°C to 80°C, for example: 60°C, 65°C, 70°C, 75°C or 80°C, etc., not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] Preferably, the concentration and crystallization treatment in step (2) comprises sequentially performing evaporation concentration, cooling crystallization and centrifugal separation treatments on the aluminum-magnesium concentrated aqueous solution.

[0032] Preferably, the pH of the magnesium precipitation treatment in step (3) is 12.5 to 14, for example, 12.5, 12.8, 13, 13.5 or 14, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the magnesium hydroxide in step (3) is pyrolyzed to obtain magnesium oxide, and the magnesium oxide is returned to step (2) as a magnesium source.

[0034] The invention uses magnesium hydroxide obtained from magnesium-aluminum concentrated water to prepare magnesium oxide, and uses the obtained magnesium oxide as a magnesium source to precipitate a magnesium borate product, which can greatly improve the added value of the product.

[0035] Preferably, the temperature of the pyrolysis treatment is 450°C to 550°C, for example, 450°C, 480°C, 500°C, 520°C or 550°C, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] (1) The present invention uses a membrane separation process to pre-separate the complex leachate to obtain lithium boron fresh water and aluminum magnesium concentrated water, which significantly improves the lithium recovery rate. At the same time, the aluminum salt product is recovered by evaporation-crystallization, and the magnesium oxide prepared by magnesium precipitation-pyrolysis is recycled to the concentrated water lithium precipitation mother liquor to prepare the magnesium borate by-product, and a high lithium recovery rate is guaranteed. The processing cost of lithium products is reduced in the whole process, the economic benefits are improved, and it is conducive to large-scale promotion and application.

[0038] (2) The lithium recovery rate of the method of the present invention can reach more than 94.8%, the aluminum recovery rate can reach more than 90.5%, the magnesium recovery rate can reach more than 97.8%, and the boron recovery rate can reach more than 92.2%. The purity of the obtained lithium phosphate can reach 99.5%, the purity of aluminum sulfate can reach 98%, the purity of magnesium oxide can reach 99%, and the purity of magnesium borate can reach 98.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a process flow chart of the comprehensive recovery method of lithium aluminum silicon boron magnesium glass provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0041] The elemental composition of the lithium aluminum silicon boron magnesium glass used in the examples and comparative examples of the present invention is shown in Table 1 below:

[0042] Table 1

[0043] element Na Ca Mg Li Al Si B content% 0.8982 0.9575 1.0378 1.8545 6.7447 26.0086 1.9264

[0044] The glass raw material used in the present invention is amorphous glass.

[0045] Example 1

[0046] This embodiment provides a comprehensive recovery method for lithium aluminum silicon boron magnesium glass. The flow diagram of the comprehensive recovery method is as follows: Figure 1 As shown, the comprehensive recovery method comprises the following steps:

[0047] (1) Waste lithium aluminum borosilicate magnesium glass is crushed, dried, crushed and sieved to obtain a powder with a particle size D50 less than 100 μm; after slurrying at a liquid-solid ratio of 3:1, sulfuric acid is added at an acid-ore ratio of 1.2:1, and acid leaching is performed at 85°C for 4 hours, and solid-liquid separation is performed to obtain acid leaching liquid and silicon slag, and the acid solution is separated by a nanofiltration membrane and concentrated by an RO membrane to obtain a lithium-boron-containing fresh water solution and an aluminum-magnesium-containing concentrated water solution, and the membrane-separated fresh water is concentrated by an RO membrane to a lithium content of 10 g / L;

[0048] (2) mixing a lithium-boron-containing freshwater solution with phosphoric acid at a phosphorus-to-lithium molar ratio of 1.2:3 (phosphorus is in excess, the lithium-to-phosphorus ratio in Li3PO4 is 3:1, so phosphorus is in excess here), adjusting the pH to 11 with liquid caustic soda, performing a lithium precipitation reaction at 80°C, and performing solid-liquid separation to obtain a lithium precipitation mother liquor and lithium phosphate, mixing the lithium precipitation mother liquor with magnesium oxide at a magnesium-to-boron molar ratio of 2:1, adjusting the pH to 10 with sulfuric acid, performing a boron precipitation reaction at 70°C, and obtaining magnesium borate and wastewater through solid-liquid separation;

[0049] (3) The aluminum-magnesium concentrated aqueous solution is evaporated and concentrated, cooled and crystallized, and then centrifuged to obtain aluminum sulfate crystals and a crystallization mother liquor. Liquid caustic soda is added to the crystallization mother liquor to adjust the pH to 13 to precipitate magnesium hydroxide. After filtration, the precipitated magnesium mother liquor is added to concentrated water to recycle and recover aluminum sulfate, and the aluminum sulfate is discharged after the sodium sulfate concentration exceeds the standard. The magnesium hydroxide is roasted at 450° C. to obtain magnesium oxide to be reused in step (2).

[0050] Example 2

[0051] This embodiment provides a comprehensive recovery method for lithium aluminum silicon boron magnesium glass. The flow diagram of the comprehensive recovery method is as follows: Figure 1 As shown, the comprehensive recovery method comprises the following steps:

[0052] (1) Waste lithium aluminum borosilicate magnesium glass is crushed, dried, crushed and sieved to obtain a powder with a particle size D50 less than 100 μm; after slurrying at a liquid-solid ratio of 2.8:1, sulfuric acid is added at an acid-ore ratio of 1:1 and acid leaching is performed at 95°C for 2 hours, solid-liquid separation is performed to obtain acid leaching liquid and silicon slag, the acid solution is separated by a nanofiltration membrane, and then concentrated by an RO membrane to obtain a lithium-boron-containing fresh water solution and an aluminum-magnesium-containing concentrated water solution, and the membrane-separated fresh water is concentrated by an RO membrane to a lithium content of 10 g / L;

[0053] (2) mixing a lithium-boron-containing freshwater solution with phosphoric acid at a phosphorus-lithium molar ratio of 1.05:3 (excess phosphorus), adjusting the pH to 11 with liquid caustic soda, performing a lithium precipitation reaction at 75°C, and performing solid-liquid separation to obtain a lithium precipitation mother liquor and lithium phosphate. The lithium precipitation mother liquor was mixed with magnesium oxide at a magnesium-boron molar ratio of 1.5:1, adjusting the pH to 9.5 with sulfuric acid, and performing a boron precipitation reaction at 80°C, and obtaining magnesium borate and wastewater through solid-liquid separation;

[0054] (3) The aluminum-magnesium concentrated aqueous solution is evaporated and concentrated, cooled and crystallized, and then centrifuged to obtain aluminum sulfate crystals and a crystallization mother liquor. Liquid caustic soda is added to the crystallization mother liquor to adjust the pH to 14 to precipitate magnesium hydroxide. After filtration, the precipitated magnesium mother liquor is added to concentrated water to recycle and recover aluminum sulfate, and the aluminum sulfate is discharged after the sodium sulfate concentration exceeds the standard; the magnesium hydroxide is roasted at 550° C. to obtain magnesium oxide to be reused in step (2).

[0055] Example 3

[0056] This embodiment provides a comprehensive recovery method for lithium aluminum silicon boron magnesium glass. The flow diagram of the comprehensive recovery method is as follows: Figure 1 As shown, the comprehensive recovery method comprises the following steps:

[0057] (1) Waste lithium aluminum borosilicate magnesium glass is crushed, dried, crushed and sieved to obtain a powder with a particle size D50 less than 100 μm; after slurrying at a liquid-solid ratio of 10:1, sulfuric acid is added at an acid-ore ratio of 1.3:1, and acid leaching is performed at 80°C for 6 hours, and solid-liquid separation is performed to obtain an acid leaching solution and silicon slag, the acid solution is separated using a nanofiltration membrane, and then concentrated using an RO membrane to obtain a lithium-boron-containing fresh water solution and an aluminum-magnesium-containing concentrated water solution, and the RO membrane is concentrated until the lithium content in the lithium-boron-containing fresh water solution is 10 g / L;

[0058] (2) mixing a lithium-boron-containing freshwater solution with phosphoric acid at a phosphorus-to-lithium molar ratio of 1.1:3 (excess phosphorus), adjusting the pH to 10.5 with liquid caustic soda, performing a lithium precipitation reaction at 90°C, and performing solid-liquid separation to obtain a lithium precipitation mother liquor and lithium phosphate; mixing the lithium precipitation mother liquor with magnesium oxide at a magnesium-boron molar ratio of 3:1, adjusting the pH to 10.5 with sulfuric acid, performing a boron precipitation reaction at 60°C, and obtaining magnesium borate and wastewater through solid-liquid separation;

[0059] (3) The aluminum-magnesium concentrated aqueous solution is evaporated and concentrated, cooled and crystallized, and then centrifuged to obtain aluminum sulfate crystals and a crystallization mother liquor. Liquid caustic soda is added to the crystallization mother liquor to adjust the pH to 12.5 and precipitate magnesium hydroxide. After filtration, the precipitated magnesium mother liquor is added to concentrated water to recycle and recover aluminum sulfate, and the aluminum sulfate is discharged after the sodium sulfate concentration exceeds the standard. The magnesium hydroxide is roasted at 500° C. to obtain magnesium oxide to be reused in step (2).

[0060] Example 4

[0061] The only difference between this embodiment and embodiment 1 is that in step (1), the RO membrane is concentrated until the lithium content in the lithium-boron-containing fresh water solution is 5 g / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0062] Example 5

[0063] The only difference between this embodiment and embodiment 1 is that the acid-ore ratio in step (1) is 0.8:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0064] Example 6

[0065] The only difference between this embodiment and embodiment 1 is that the acid-ore ratio in step (1) is 1.5:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0066] Example 7

[0067] The only difference between this embodiment and embodiment 1 is that the molar ratio of phosphorus to lithium in step (2) is 0.8:3, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0068] Example 8

[0069] The only difference between this embodiment and embodiment 1 is that the molar ratio of phosphorus to lithium in step (2) is 1.5:3, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0070] Example 9

[0071] The only difference between this embodiment and embodiment 1 is that the molar ratio of magnesium to boron in step (2) is 1:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0072] Example 10

[0073] The only difference between this embodiment and embodiment 1 is that the molar ratio of magnesium to boron in step (2) is 4:1, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0074] Example 11

[0075] The only difference between this comparative example and Example 1 is that no RO membrane is used in step (1), and the other conditions and parameters are exactly the same as those in Example 1.

[0076] Comparative Example 1

[0077] The only difference between this comparative example and Example 1 is that step (1) does not use a nanofiltration membrane, and the other conditions and parameters are exactly the same as those in Example 1.

[0078] Performance testing:

[0079] The purity of lithium phosphate, aluminum sulfate, magnesium oxide and magnesium borate obtained in the embodiment and the comparative example was tested, and the recovery rates of lithium, aluminum, magnesium and boron were calculated. The test results are shown in Table 2:

[0080] Table 2

[0081]

[0082]

[0083] As can be seen from Table 2, from Examples 1-10, the lithium recovery rate of the method of the present invention can reach more than 78.4%, the aluminum recovery rate can reach more than 87%, the magnesium recovery rate can reach more than 95.4%, and the boron recovery rate can reach more than 88.5%. The purity of the obtained lithium phosphate can reach more than 99.5%, the purity of aluminum sulfate can reach 98%, the purity of magnesium oxide can reach 99%, and the purity of magnesium borate can reach more than 98.5%. The acid-ore ratio in the leaching process has a significant impact on the recovery rate of each element. The leaching liquid-solid ratio, the liquid concentration after membrane concentration, and the lithium precipitation conditions have a significant impact on the recovery rate of lithium phosphate. The magnesium-boron ratio has a significant impact on the boron removal effect and product purity. The preparation of aluminum sulfate by the crystallization method is less affected by other factors due to the reuse of the mother liquor, and the preparation of magnesium oxide is affected by the precipitation pH. By adjusting the above conditions, the lithium recovery rate of the method can reach more than 94.8%, the aluminum recovery rate can reach more than 90.5%, the magnesium recovery rate can reach more than 97.8%, and the boron recovery rate can reach more than 92.2%. The purity of the prepared lithium phosphate can reach 99.5%, the purity of aluminum sulfate can reach 98%, the purity of magnesium oxide can reach 99%, and the purity of magnesium borate can reach 98.5%.

[0084] By comparison between Example 1 and Example 4, it can be seen that in the comprehensive recovery method of lithium aluminum silicate boron magnesium glass according to the present invention, the lithium content in the lithium-boron-containing freshwater solution obtained after RO membrane concentration will affect the subsequent lithium recovery rate. When the lithium content in the lithium-boron-containing freshwater solution obtained after RO membrane concentration is controlled at 8 g / L to 20 g / L, the lithium recovery rate is relatively high. If the lithium content in the lithium-boron-containing freshwater solution obtained after RO membrane concentration is too low, the lithium concentration is too low, resulting in the inability to be completely captured by the phosphorus source to form lithium phosphate, resulting in a significant decrease in the lithium recovery rate.

[0085] By comparing Example 1 with Examples 5-6, it can be seen that in the comprehensive recovery method of lithium aluminum silicon boro magnesium glass of the present invention, the acid-ore ratio of the heated acid leaching in step (1) will affect the recovery effect. When the acid-ore ratio is controlled within (1-1.3):1, the recovery effect is better. If the acid-ore ratio is too low, the leaching of each element is insufficient and the recovery rate is low. If the acid-ore ratio is too high, it may lead to an increase in the silicon leaching rate, difficulty in filtration and increased ineffective costs.

[0086] By comparing Example 1 with Examples 7-8, it can be seen that in the comprehensive recovery method of lithium aluminum silicon boro magnesium glass according to the present invention, the amount of phosphorus source added in step (2) affects the recovery effect. When the phosphorus-lithium molar ratio is controlled within (1-1.2):3, the recovery effect is better. If the amount of phosphorus source added is too low, the lithium phosphate precipitation is incomplete and the lithium recovery rate is reduced. If the amount of phosphorus source added is too high, the cost increases.

[0087] By comparing Example 1 with Examples 9-10, it can be seen that in the comprehensive recovery method of lithium aluminum silicon boron magnesium glass according to the present invention, the amount of magnesium source added in step (2) affects the recovery effect. The recovery effect is better when the magnesium-boron molar ratio is controlled at (1.5-3):1. If the amount of magnesium source added is too low, boron removal is incomplete, the recovery rate is reduced, and the back-end treatment of boron in the wastewater is more complicated. If the amount of magnesium source added is too high, excess magnesium is converted into magnesium hydroxide, affecting the purity of magnesium borate.

[0088] From the comparison between Example 1 and Example 11, it can be seen that in the comprehensive recovery method of lithium aluminum silicon boro magnesium glass of the present invention, the use of RO membrane concentration can significantly improve the recovery rate of lithium.

[0089] By comparing Example 1 and Comparative Example 1, it can be seen that the membrane separation and concentration process of nanofiltration membrane separation and RO membrane concentration is used to treat the lithium aluminum borosilicate magnesium glass acid leachate, which can achieve high-selective separation of high-value elements lithium, boron and aluminum and magnesium, effectively avoid the problem of lithium entrainment / adsorption loss in the traditional lithium aluminum separation process, and promote the diversified treatment of elements such as aluminum and magnesium.

[0090] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A comprehensive recovery method for lithium aluminum silicon boro magnesium glass, characterized in that: The comprehensive recovery method comprises the following steps: (1) crushing waste lithium aluminum borosilicate magnesium glass into pulp, subjecting it to heated acid leaching treatment to obtain silicon slag and acid leaching solution, and subjecting the acid leaching solution to membrane separation and concentration treatment, and performing solid-liquid separation to obtain a lithium-boron-containing fresh water solution and an aluminum-magnesium-containing concentrated water solution; (2) mixing the lithium-boron-containing freshwater solution with a phosphorus source to carry out lithium precipitation reaction, and performing solid-liquid separation to obtain a lithium precipitation mother liquor and lithium phosphate, and mixing the lithium precipitation mother liquor with a magnesium source to carry out boron precipitation reaction, and obtaining magnesium borate and wastewater through solid-liquid separation; (3) The aluminum-magnesium concentrated aqueous solution is concentrated and crystallized to obtain aluminum salt crystals and a crystallization mother liquor, and the crystallization mother liquor is subjected to magnesium precipitation treatment, and solid-liquid separation is performed to obtain magnesium hydroxide.

2. The comprehensive recovery method according to claim 1, characterized in that: The median particle size D50 of the waste lithium aluminum borosilicate magnesium glass after the pulverization in step (1) is less than 100 μm; Preferably, the solvent for the slurrying in step (1) comprises water; Preferably, the liquid-to-solid mass ratio of the slurry in step (1) is (2.8-10):1; Preferably, the acid solution used in the heated acid leaching treatment in step (1) comprises a sulfuric acid solution; Preferably, the acid-ore ratio of the heated acid leaching treatment in step (1) is (1-1.3):1; Preferably, the temperature of the heating acid leaching treatment in step (1) is 80° C. to 95° C.; Preferably, the heating and acid leaching treatment time in step (1) is 2 hours to 6 hours.

3. The comprehensive recovery method according to claim 1 or 2, characterized in that: The membrane separation and concentration treatment in step (1) comprises separating the acid solution using a nanofiltration membrane and then concentrating it using an RO membrane; Preferably, after the RO membrane is concentrated, the lithium content of the obtained lithium-boron-containing freshwater solution is 8 g / L to 20 g / L.

4. The comprehensive recovery method according to any one of claims 1 to 3, characterized in that: The phosphorus source in step (2) includes phosphoric acid; Preferably, the molar ratio of phosphorus in the phosphorus source to lithium in the lithium-boron-containing freshwater solution in step (2) is (1-1.2):

3.

5. The comprehensive recovery method according to any one of claims 1 to 4, characterized in that: The pH of the lithium precipitation reaction in step (2) is 10-11; Preferably, the temperature of the lithium precipitation reaction in step (2) is 75°C to 90°C.

6. The comprehensive recovery method according to any one of claims 1 to 5, characterized in that: The magnesium source in step (2) comprises magnesium oxide; Preferably, the molar ratio of the magnesium element in the magnesium source in step (2) to the boron element in the lithium precipitation mother liquor is (1.5-3):

1.

7. The comprehensive recovery method according to any one of claims 1 to 6, characterized in that: The pH of the boron precipitation reaction in step (2) is 9.5 to 10.5; Preferably, the temperature of the boron precipitation reaction in step (2) is 60°C to 80°C.

8. The comprehensive recovery method according to any one of claims 1 to 7, characterized in that: The concentration and crystallization treatment in step (2) comprises sequentially performing evaporation and concentration, cooling and crystallization, and centrifugal separation treatments on the aluminum-magnesium concentrated aqueous solution.

9. The comprehensive recovery method according to any one of claims 1 to 8, characterized in that: The pH of the magnesium precipitation treatment in step (3) is 12.5-14.

10. The comprehensive recovery method according to any one of claims 1 to 9, characterized in that: The magnesium hydroxide in step (3) is pyrolyzed to obtain magnesium oxide, and the magnesium oxide is returned to step (2) as a magnesium source; Preferably, the temperature of the pyrolysis treatment is 450°C to 550°C.

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