A lithium-containing aluminum electrolyte waste roasting aid, a preparation method and application thereof, and an application method and roasted clinker in lithium-containing aluminum electrolyte waste resource utilization

Abstract

This invention provides a roasting aid for lithium-containing aluminum electrolyte waste, its preparation method, application, and application method in the resource recovery of lithium-containing aluminum electrolyte waste, as well as roasted clinker, relating to the field of lithium-containing waste recycling. The roasting aid for lithium-containing aluminum electrolyte waste contains a first calcium-containing substance and a second calcium-containing substance. The first calcium-containing substance is at least one of calcium sulfate, calcium bisulfate, calcium carbonate, or calcium bicarbonate. The second calcium-containing substance is at least one of calcium carbonate, bicarbonate, sulfate, bisulfate, hydroxide, oxide, or chloride. The second calcium-containing substance and the first calcium-containing substance contain different or dissimilar anions. The molar amount of calcium in the first calcium-containing substance accounts for 40%-80% of the total molar amount of calcium. Furthermore, the ratio of the total molar amount of calcium in the first and second calcium-containing substances to the molar amount of aluminum in the lithium-containing aluminum electrolyte waste is 1-4:1. The roasting aid of this invention has high roasting efficiency, good roasting effect, and low energy consumption.

Description

Technical Field

[0001] This application relates to the field of lithium-containing waste recycling, and in particular to a roasting aid for lithium-containing aluminum electrolyte waste, its preparation method, application, and application method in the resource utilization of lithium-containing aluminum electrolyte waste, as well as roasted clinker. Background Technology

[0002] The lithium-containing aluminum electrolyte waste currently existing and continuously produced in my country is a hazardous solid waste containing toxic and harmful substances such as fluorides and cyanides, which must be treated to render it harmless. At the same time, it is also an important secondary lithium resource. The Li content in lithium-containing aluminum electrolyte is as high as 1-3%, which is equivalent to 2-6.5% Li2O content, close to 1.5-7% in spodumene ore, and its potential lithium extraction value is very high.

[0003] Due to their dense and stable structure, lithium-containing aluminum electrolytes are difficult to effectively destroy or transform the crystal structure of their various phases through conventional acid leaching. However, calcination at high temperatures using calcination aids can promote this process. Therefore, current technologies often involve adding calcination aids for calcination treatment followed by leaching.

[0004] For example, CN114804171A uses aluminum sulfate as a roasting aid. The crushed lithium-containing aluminum electrolyte is mixed with aluminum sulfate, ground, and pressed into lumps before being roasted in a high-temperature furnace. Afterward, it is leached in water, where aluminum enters the slag phase as aluminum fluoride, and sodium and lithium enter the liquid phase as sulfates. All of the above methods using aluminum sulfate as an aid require a large amount of aluminum sulfate, with the aluminum sulfate added to the lithium-containing aluminum electrolyte at almost a 1:1 mass ratio. This not only consumes a large amount of expensive aluminum sulfate (approximately 1900 yuan / ton) but also generates a slag volume equivalent to the amount of lithium-containing aluminum electrolyte. This results in high process costs, large amounts of process materials and slag, which is unfavorable for actual industrial production.

[0005] Existing technologies also involve other auxiliary treatment processes, such as CN115011798A, which solves the problems of low lithium leaching rate and the use of corrosive concentrated acids in lithium-aluminum electrolytes by adding auxiliary materials for roasting and acid leaching. The auxiliary materials are selected from the following components: NaCl, Na2SO4, NaHSO4, Na2O, NaOH, Na2CO3, NaHCO3, KCl, K2SO4, KHSO4, K2O, KOH, K2CO3, KHCO3, Fe2O3, FeSO4, MnO2; or selected from the following components: a) containing alkaline earth metal elements. a) Salts or oxides of elements; b) Salts or oxides containing lanthanide metals; c) Salts or oxides containing silicon or lead; d) Ores containing one or more of the above elements, as well as production residues or waste; or salts or oxides containing magnesium, calcium, barium, silicon or lead, or ores containing alkaline earth metals, Si or Pb, as well as production residues or waste, preferably one or more of MgO, MgCO3, MgSO4, CaO, CaCO3, CaSO4, BaO, BaCO3, BaSO4, SiO2, magnesia, silica, limestone or lime. This patent provides numerous auxiliary roasting schemes, but the overall lithium leaching rate is only around 70%-80%, which cannot achieve effective recovery of high-value lithium. Secondly, the high-temperature roasting time is as long as 8 hours or even 11 hours, resulting in low process efficiency and high energy consumption. Moreover, it does not disclose the specific addition of auxiliary agents and the basis for their addition. According to the limited examples, it is only known that it contains salts or oxides of alkaline earth metal elements, which are added to lithium-containing aluminum electrolytes at a 1:1 mass ratio. This has the defects of large amount of auxiliary materials, simple and crude addition method, and lack of basis for implementation. In addition, since the roasting process does not achieve sufficient phase transformation reaction, the subsequent acid leaching also has the problems of long leaching time (6-8 hours), low efficiency, high leaching acid concentration, high requirements for equipment corrosion resistance, and most of the aluminum and iron enter the acid leaching liquid phase with the lithium, making it difficult to avoid the subsequent lithium and aluminum separation difficulties that are common in the lithium extraction industry.

[0006] However, due to the complex composition of lithium-containing aluminum electrolytes, high-temperature roasting inevitably involves complex multiphase reactions. Because of the complex composition of lithium-containing aluminum electrolytes, the complex high-temperature phase transformation system during roasting, and the numerous interdependent and influencing factors, it is difficult to conduct in-depth and clear research and elucidation of the roasting reaction mechanism. Existing technologies lack clear guidance on how to efficiently roast and transform lithium-containing aluminum electrolytes. Although many researchers have proposed various auxiliary roasting schemes, they often face problems such as unsatisfactory lithium phase transformation, failure to transform into easily leached, especially selectively leached, lithium-containing compounds, slow conversion rates, low conversion rates, high costs and large dosages of roasting aids, and unstable roasting effects leading to large fluctuations in subsequent lithium leaching recovery rates. This not only wastes resources but also results in a large amount of production investment not yielding returns, making the industrialization of lithium-containing aluminum electrolyte recovery extremely difficult and challenging. Summary of the Invention

[0007] This invention provides a lithium-containing aluminum electrolyte roasting aid, a preparation method, an application, a method for its application in the resource recovery of lithium-containing aluminum electrolyte waste, and the roasted clinker obtained therefrom, in order to solve at least one technical problem in the background art.

[0008] As a first aspect of the present invention, a roasting aid for lithium-aluminum electrolyte waste is provided, the roasting aid comprising:

[0009] The first calcium-containing substance is at least one of calcium sulfate, calcium bisulfate, calcium carbonate, or calcium bicarbonate, for example, one, two, three, or four of them.

[0010] The second calcium-containing substance is at least one of the following: calcium carbonate, bicarbonate, sulfate, hydrogen sulfate, hydroxide, oxide, and chloride. For example, it may contain one, two, three, four, five, or six of these. Furthermore, the second calcium-containing substance contains anions that are different or dissimilar to the first calcium-containing substance. For instance, when the first calcium-containing substance is calcium sulfate and / or calcium bisulfate, the second calcium-containing substance is not only calcium sulfate and / or calcium bisulfate; similarly, when the first calcium-containing substance is calcium carbonate and / or calcium bicarbonate, the second calcium-containing substance is not only calcium bicarbonate and / or calcium carbonate. By combining different calcium salts, the guiding and promoting effect of the additives on the calcination reaction is ensured.

[0011] The calcium molar content of the first calcium-containing substance accounts for 40%-80% of the total calcium molar content of the calcination aid, for example, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%.

[0012] And the ratio of the total molar amount of calcium in the first calcium-containing substance and the second calcium-containing substance to the molar amount of aluminum in the lithium-aluminum electrolyte waste is 1-4:1, for example, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, 4:1.

[0013] Among them, similar anions, such as carbonate and bicarbonate ions, and sulfate and bisulfate ions, are used. By combining different calcium-containing compounds, the guiding and promoting effects of the additives on the roasting reaction are ensured. Through control of the types, molar ratios, and lithium-containing aluminum electrolyte ratios of different calcium-containing substances, the corresponding additives can rapidly and efficiently convert lithium in the lithium-containing aluminum electrolyte into easily soluble lithium compounds, thereby simplifying and optimizing lithium recovery from the lithium-containing aluminum electrolyte, while shortening the roasting time and improving the roasting furnace capacity and roasting efficiency.

[0014] Furthermore, the calcium molar content in the first calcium-containing substance accounts for 50%-80% of the total calcium molar content.

[0015] Furthermore, the ratio of the total calcium molar amount of the first and second calcium-containing substances to the aluminum molar amount in the lithium-aluminum electrolyte waste is 1.5-3.5:1.

[0016] Furthermore, the first calcium-containing substance is at least one of calcium sulfate or calcium bisulfate.

[0017] Furthermore, the second calcium-containing substance is at least one of calcium oxide, hydroxide, carbonate, bicarbonate, and chloride.

[0018] Furthermore, the calcium molar content in the first calcium-containing substance accounts for 60-75% of the total calcium molar content.

[0019] Furthermore, the ratio of the total molar amount of calcium in the first and second calcium-containing substances to the molar amount of aluminum in the lithium-aluminum electrolyte waste is 2-3:1.

[0020] Furthermore, the first calcium-containing substance is calcium sulfate or calcium bisulfate.

[0021] Furthermore, the second calcium-containing substance is calcium hydroxide and / or calcium oxide; or, the second calcium-containing substance is calcium carbonate and calcium chloride; or, the second calcium-containing substance is a combination of at least one of calcium hydroxide and calcium oxide with at least one of calcium chloride and calcium carbonate.

[0022] By further combining and optimizing the proportions of calcium-containing additives, the transformation of impurities such as calcium, aluminum, and fluorine into stable phases can be further promoted, or they can be transformed into stable phases and enter the slag during the subsequent wet lithium extraction process, thereby achieving separation from lithium elements, reducing the pressure of separating and removing impurities from lithium-containing leachate, shortening the wet processing flow, improving processing efficiency, and reducing costs.

[0023] As a second aspect of the present invention, a method for preparing the lithium-aluminum electrolyte waste roasting aid as described above is provided, comprising the following steps:

[0024] Provide the first calcium-containing substance, the second calcium-containing substance, and lithium-aluminum electrolyte waste;

[0025] The first and second calcium-containing substances are prepared according to the ratio of the calcium molar amount in the first calcium-containing substance to the total calcium molar amount in the additive, the ratio of the total calcium molar amount of the first and second calcium-containing substances to the aluminum molar amount in the lithium-aluminum electrolyte waste, and the aluminum molar amount in the lithium-aluminum electrolyte waste. The prepared first and second calcium-containing substances are then mixed to obtain the lithium-aluminum electrolyte waste roasting additive.

[0026] As a third aspect of the present invention, the application of the lithium-containing aluminum electrolyte waste roasting aid described above in the recycling of lithium-containing aluminum electrolyte waste is provided.

[0027] Applying the lithium-aluminum electrolyte waste roasting aid of this invention to the recycling of lithium-aluminum electrolyte waste has significant comprehensive economic and social benefits.

[0028] As a fourth aspect of the present invention, a method for applying the above-mentioned calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste is provided, the method comprising the following steps: mixing lithium-containing aluminum electrolyte waste with the calcination aid and then calcining it.

[0029] Furthermore, the calcination temperature is 750-1100℃, for example, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, 810℃, 820℃, 830℃, 840℃, 850℃, 860℃, 870℃, 880℃, 890℃, 900℃, 910℃, 920℃, 930℃, 940℃, 950℃, 960℃, 970℃, 980℃, 990℃, 1000℃, 1010℃, 1020℃, 1030℃, 1040℃, 1050℃, 1060℃, 1070℃, 1080℃, 1090℃, and 1100℃.

[0030] Furthermore, the calcination temperature is 760-1050℃, and even more specifically 780-900℃.

[0031] Furthermore, the roasting time is 0.75h-5h, for example, 45min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min, 190min, 200min, 210min, 220min, 230min, 240min, 250min, 260min, 270min, 280min, 290min, or 300min.

[0032] Furthermore, the roasting time is 1-3 hours, and even more specifically 1-2 hours.

[0033] The existence of lithium in lithium-containing aluminum electrolytes is highly complex. Besides existing as LiF, lithium also exists to varying degrees as Li₂NaAlF₆, LiNa₂AlF₆, and other forms. Through long-term research, the inventors discovered that by controlling specific calcium salt mixtures, the total calcium addition, and different calcium salt ratios, the lithium-containing phase transformation in lithium-containing aluminum electrolytes can be achieved through short-time calcination. This transforms lithium into easily soluble lithium aluminum fluoride compounds, and ensures that most of the fluorine and aluminum exist as calcium aluminum fluorides such as Ca₂AlF₇ and CaAlF₅, which are difficult to dissolve through acid leaching. Furthermore, calcium will further bind with fluorine (F) from the raw materials. The formation of insoluble CaF2 by elements not only significantly improves lithium conversion efficiency but also significantly enhances the lithium leaching rate in subsequent wet leaching, greatly reducing roasting energy consumption. Furthermore, during acid leaching, only a portion of aluminum enters the liquid phase. Particularly when a specific calcium salt (calcium sulfate + calcium hydroxide) is used, under specific acid leaching solutions, the aluminum dissolved in the solution by specific fluorinated aluminum lithium compounds can be converted into more stable aluminum-containing compounds by other components in the leaching system and re-enter the slag phase. This results in an aluminum leaching rate in high-aluminum lithium-containing aluminum electrolytes as low as below 0.1%, greatly reducing the aluminum removal burden and lithium loss in subsequent leaching solutions. In addition, the precise addition of calcium-containing substances avoids the adverse effects of excessive additives on additive costs, process materials, and slag volume.

[0034] As a fifth aspect of the present invention, a roasted clinker is provided by a method for applying the roasting aid in the resource recovery of lithium-aluminum electrolyte waste.

[0035] The clinker has the advantage of being easy to leach for lithium extraction, while impurities such as fluorine, calcium, and aluminum are difficult to leach out.

[0036] Compared with the prior art, the beneficial effects of the present invention include:

[0037] 1. Provide calcium-containing additives with specific correlation to the composition of lithium-containing aluminum electrolyte waste. This effectively avoids the increased time and investment caused by repeated trials and formulation of additive schemes due to batch raw material composition fluctuations, or the insufficient or excessive addition of additives due to blind adjustment of additive use, resulting in incomplete phase transformation, low lithium leaching rate in subsequent leaching stages, or waste of additives, low effective batch processing capacity, and large slag volume caused by blindly adding excessive amounts.

[0038] 2. By combining specific calcium-containing substances in a precise and synergistic manner, the reaction thermodynamic conditions of a single additive are altered. This reduces the activation energy for the conversion of lithium-containing phases into fluorinated aluminum lithium phases, promotes the conversion of lithium-containing phases into easily leached phases and drives the conversion process, and converts aluminum, calcium, and fluorine into more stable compound phases. This significantly shortens the duration of the high-temperature, high-energy-consumption roasting process. The overall roasting process time and roasting energy consumption can be reduced by more than 60-90%, significantly improving production efficiency and reducing operational difficulty and investment.

[0039] 3. By combining and allocating calcination aids, the lithium leaching rate is significantly improved, reaching a maximum of 99.75%, which is more than 40% higher than existing technologies. Simultaneously, the leaching of fluorine and aluminum impurities is suppressed to varying degrees. Based on the efficient conversion of lithium-containing phases during the calcination stage, approximately 80% selective lithium leaching can be achieved through neutral leaching. The aluminum leaching rate during neutral leaching is only about 0.001%, and the fluorine leaching rate is only about 0.005%, laying a solid foundation for the subsequent separation and purification of most lithium in lithium-containing aluminum electrolytes. The Li content in the acid leaching residue is basically <0.1wt.%, with a minimum of only 0.002wt.%, and the lithium leaching rate is above 85%, reaching a maximum of 99.75%. The fluorine leaching rate is controlled below 2.5%, mostly below 1%, and the aluminum leaching rate during acid leaching is as low as 0.003%. Most of the fluorine and aluminum elements remain in the slag phase, which not only greatly reduces the burden of subsequent wet lithium extraction and impurity removal, and simplifies the impurity removal process, but also effectively avoids the entrainment loss of lithium caused by aluminum removal and defluorination in the solution. In particular, for low-fluorine and low-aluminum neutral leaching solutions, there is no need for aluminum removal and defluorination stages, which not only effectively improves lithium recovery efficiency, but also has significant benefits for energy conservation, emission reduction and emission reduction.

[0040] 4. The roasted material obtained by the roasting method of the present invention has relaxed subsequent acid leaching conditions, the acid leaching process is efficient and simple to operate, and lithium can be leached efficiently under low acid conditions. The equipment requirements are low, the operating conditions are friendly, and it is conducive to the return and recycling of acid leaching solution.

[0041] 5. No harmful volatile substances such as HF and sulfur dioxide are generated during the roasting process. It is a neutral roasting process, with friendly operating conditions and low equipment requirements.

[0042] 6. The overall process is simple to operate, the lithium-containing phase conversion is complete and the conversion efficiency is high, the overall operating cost and energy consumption of industrialization are low, laying a good foundation for subsequent lithium leaching and extraction. The calcined clinker can achieve rapid lithium leaching through simple weak acid leaching, and the lithium-containing aluminum electrolyte has high recovery value. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation on the scope of this application.

[0044] Figure 1 The image shows the XRD pattern of lithium-aluminum electrolyte waste 1.

[0045] Figure 2 The XRD patterns of the roasted clinker before and after leaching in Example 1 of the present invention are shown.

[0046] Figure 3The XRD patterns of the roasted clinker before and after leaching in Comparative Example 2 of this invention are shown. Detailed Implementation

[0047] The present invention will be described in detail below with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0048] The lithium content in lithium-containing aluminum electrolyte waste is generally greater than 0.5 wt.%, the aluminum content is generally greater than 5 wt.%, and the fluorine content fluctuates greatly.

[0049] In the following examples and comparative examples, the main components of lithium-aluminum electrolyte waste 1 used in Examples 1-10 and the comparative examples are as follows: 15.85 wt.% Al, 2.06 wt.% Li, 13.82 wt.% F. The XRD pattern of this lithium-aluminum electrolyte waste 1 is shown below. Figure 1 As shown.

[0050] The main components of the lithium-aluminum electrolyte waste 2 used in Examples 11-18 are as follows: 13.45 wt.% Al, 1.38 wt.% Li, and 11.68 wt.% F.

[0051] Example 1

[0052] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium carbonate and calcium sulfate, wherein the molar ratio of calcium carbonate to calcium sulfate is 1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte waste to be treated is 2.5:1.

[0053] The preparation method of the lithium-aluminum electrolyte waste roasting aid in this embodiment is as follows: calcium carbonate, calcium sulfate, and lithium-aluminum electrolyte waste are provided; based on the molar ratio of calcium carbonate to calcium sulfate of 1:1, the ratio of the total calcium molar amount of calcium carbonate and calcium sulfate to the aluminum molar amount in the lithium-aluminum electrolyte waste of 2.5:1, and the aluminum molar amount in 1 kg of lithium-aluminum electrolyte waste, 7.34 mol of calcium sulfate (998.24 g) and calcium carbonate (734 g) are weighed and mixed to obtain the lithium-aluminum electrolyte waste roasting aid for later use (the preparation methods of the roasting aids in the following embodiments and comparative examples are similar and will not be repeated).

[0054] The application method of the roasting aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the aforementioned roasting aid that has passed through a 100-mesh sieve is mixed with 1 kg of lithium-containing aluminum electrolyte powder, the mixture is placed in a roasting furnace, the furnace door is closed, and it is roasted at 800°C for 90 minutes to obtain roasted clinker.

[0055] The calcined clinker was ground to pass through a 100-mesh sieve and leached at 60°C for 90 min in a leaching system with an initial liquid-to-solid ratio of 3:1 (volume-to-mass ratio L / kg, the same below) and a pH of 2.3±0.2, to obtain a lithium-containing leachate and leaching residue. The XRD patterns of the calcined clinker before and after leaching are shown below. Figure 2 As shown.

[0056] In this embodiment, the lithium leaching rate of the roasted clinker was 96.48%, the fluorine leaching rate was 0.49%, and the aluminum leaching rate was 36.36%.

[0057] Example 2

[0058] In this embodiment, the calcination aid for lithium-aluminum electrolyte waste is a mixture of calcium carbonate and calcium hydroxide, wherein the molar ratio of calcium carbonate to calcium hydroxide is 1:1, and the molar ratio of calcium in the calcination aid to aluminum in the lithium-aluminum electrolyte is 1:1.

[0059] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through an 80-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and it is calcined at 750°C for 90 minutes to obtain calcined clinker.

[0060] The calcined clinker was ground to pass through 100 mesh and reacted at 65°C for 90 min in a leaching system with pH 2±0.2 and an initial liquid-to-solid ratio of 3:1 to obtain leaching solution and leaching residue. In this example, the lithium leaching rate of the calcined clinker was 86.16%, the fluorine leaching rate was 0.15%, and the aluminum leaching rate was 44.37%.

[0061] Example 3

[0062] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium chloride, wherein the molar ratio of calcium sulfate to calcium chloride is 1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2:1.

[0063] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 780°C for 120 minutes to obtain calcined clinker.

[0064] The calcined clinker was ground to pass through an 80-mesh sieve and reacted in a leaching system with a pH of 2.5 ± 0.5 and an initial liquid-to-solid ratio of 3:1 at 40°C for 120 minutes. The mixture was then filtered to obtain the leachate and leaching residue. In this example, the lithium leaching rate of the calcined clinker was 87.19%, the fluorine leaching rate was 0.48%, and the aluminum leaching rate was 29.34%.

[0065] Example 4

[0066] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium hydroxide, wherein the molar ratio of calcium sulfate to calcium hydroxide is 1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1.

[0067] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 70-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 800°C for 120 minutes to obtain calcined clinker.

[0068] The calcined clinker was ground to pass through a 100-mesh sieve and reacted in a leaching system with a pH of 2.5 ± 0.5 and an initial liquid-to-solid ratio of 3:1 at 60°C for 120 minutes, followed by filtration to obtain leaching solution and leaching residue. In this example, the lithium leaching rate of the calcined clinker was 92.15%, the fluorine leaching rate was 0.04%, and the aluminum leaching rate was 0.04%.

[0069] Example 5

[0070] In this embodiment, the calcination aid for lithium-aluminum electrolyte waste is a mixture of calcium carbonate and calcium chloride, wherein the molar ratio of calcium carbonate to calcium chloride is 1:1, and the molar ratio of calcium in the calcination aid to aluminum in the lithium-aluminum electrolyte is 1.5:1.

[0071] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 50-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 875°C for 60 minutes to obtain calcined clinker.

[0072] The calcined clinker was ground to pass through a 120-mesh sieve and reacted at 50°C for 60 minutes in a leaching system with a pH of 2.5 ± 0.5 and an initial liquid-to-solid ratio of 3:1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 87.53%, the fluorine leaching rate was 0.37%, and the aluminum leaching rate was 45.13%.

[0073] Example 6

[0074] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium carbonate and calcium sulfate, wherein the molar ratio of calcium carbonate to calcium sulfate is 1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 4:1.

[0075] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 850°C for 75 minutes to obtain calcined clinker.

[0076] The calcined clinker was ground to pass through a 70-mesh sieve and reacted at 95°C for 30 min in a leaching system with an initial liquid-to-solid ratio of 3:1 and a pH of 3.5 ± 0.5, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 89.80%, the fluorine leaching rate was 2.82%, and the aluminum leaching rate was 22.49%.

[0077] Example 7

[0078] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium carbonate, wherein the molar ratio of calcium sulfate to calcium carbonate is 2:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 3:1.

[0079] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 900°C for 150 minutes to obtain calcined clinker.

[0080] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 70°C for 120 min in a leaching system with an initial liquid-to-solid ratio of 3:1 and a pH of 1.5 ± 0.1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 87.76%, the fluorine leaching rate was 0.29%, and the aluminum leaching rate was 43.53%.

[0081] Example 8

[0082] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium carbonate, wherein the molar ratio of calcium sulfate to calcium carbonate is 2:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 3:1.

[0083] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 900°C for 150 minutes to obtain calcined clinker.

[0084] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 80°C for 180 min in a leaching system with an initial liquid-to-solid ratio of 3:1 and a pH of 5.0 ± 0.1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 89.47%, the fluorine leaching rate was 0.71%, and the aluminum leaching rate was 6.98%.

[0085] Example 9

[0086] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium hydroxide, wherein the molar ratio of calcium sulfate to calcium hydroxide is 1.5:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1.

[0087] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 900°C for 180 minutes to obtain calcined clinker.

[0088] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 90°C for 90 min in a leaching system with an initial liquid-to-solid ratio of 5:1 and a pH of 3.5±0.1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 89.35%, the fluorine leaching rate was 0.37%, and the aluminum leaching rate was 5.19%.

[0089] Example 10

[0090] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium hydroxide, wherein the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1, and the molar ratio of calcium sulfate to calcium hydroxide is 1.5:1.

[0091] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 900°C for 180 minutes to obtain calcined clinker.

[0092] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 95°C for 60 minutes in a leaching system with a pH of 2.5 ± 0.1 and an initial liquid-to-solid ratio of 10:1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 98.68%, the fluorine leaching rate was 1.27%, and the aluminum leaching rate was 0.03%.

[0093] Example 11

[0094] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium carbonate, wherein the molar ratio of calcium sulfate to calcium carbonate is 3:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1.

[0095] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 850°C for 90 minutes to obtain calcined clinker.

[0096] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 50°C for 240 min in a leaching system with an initial liquid-to-solid ratio of 2:1 and a pH of 1±0.1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 91.41%, the fluorine leaching rate was 0.47%, and the aluminum leaching rate was 64.35%.

[0097] Example 12

[0098] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium carbonate, wherein the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1, and the molar ratio of calcium sulfate to calcium carbonate is 3:1.

[0099] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 850°C for 90 minutes to obtain calcined clinker.

[0100] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 75°C for 120 min in a leaching system with an initial liquid-to-solid ratio of 15:1 and a pH of 4±0.1 to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 89.16%, the fluorine leaching rate was 1.66%, and the aluminum leaching rate was 1.70%.

[0101] Example 13

[0102] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate, calcium carbonate, and calcium chloride, wherein the molar ratio of calcium sulfate, calcium carbonate, and calcium chloride is 1:1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 3:1.

[0103] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 850°C for 90 minutes to obtain calcined clinker.

[0104] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 65°C for 120 min in a leaching system with an initial liquid-to-solid ratio of 6:1 and a pH of 2.5 ± 0.1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 93.72%, the fluorine leaching rate was 2.31%, and the aluminum leaching rate was 15.58%.

[0105] Example 14

[0106] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate, calcium carbonate, and calcium chloride, wherein the molar ratio of calcium sulfate, calcium carbonate, and calcium chloride is 1:1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 3:1.

[0107] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 850°C for 90 minutes to obtain calcined clinker.

[0108] The calcined clinker was ground to pass through a 100-mesh sieve and reacted in a leaching system with an initial liquid-to-solid ratio of 8:1 and a pH of 2.0 ± 0.1 at 25°C for 120 min to obtain a leachate and leaching residue. In this example, the lithium leaching rate of the calcined clinker was 99.75%, the fluorine leaching rate was 1.97%, and the aluminum leaching rate was 22.21%.

[0109] Example 15

[0110] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium carbonate, wherein the molar ratio of calcium sulfate to calcium carbonate is 1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1.

[0111] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 1100℃ for 45 minutes to obtain calcined clinker.

[0112] The calcined clinker was ground to pass through a 100-mesh sieve and reacted at 60°C for 75 minutes in a leaching system with an initial liquid-to-solid ratio of 4:1 and a pH of 2.5 ± 0.1, to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 86.17%, the fluorine leaching rate was 0.90%, and the aluminum leaching rate was 35.69%.

[0113] Example 16

[0114] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate, calcium chloride, and calcium oxide, wherein the molar ratio of calcium sulfate, calcium chloride, and calcium oxide is 1:1:1, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1.

[0115] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the lithium-containing aluminum electrolyte powder that has passed through a 100-mesh sieve is mixed with the calcination aid, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 800°C for 90 minutes to obtain calcined clinker.

[0116] The calcined clinker was ground to pass through a 100-mesh sieve and reacted in a leaching system with an initial solid-liquid ratio of 3:1 and a pH of 2.5 ± 0.1 at 60°C for 90 min to obtain a leachate and a leaching residue. In this example, the lithium leaching rate of the calcined clinker was 93.98%, the fluorine leaching rate was 0.77%, and the aluminum leaching rate was 6.19%.

[0117] Example 17

[0118] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate and calcium hydroxide, wherein the molar ratio of calcium sulfate to calcium oxide is 3:2, and the molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1.

[0119] The application method of the calcination aid in the resource utilization of lithium-containing aluminum electrolyte waste in this embodiment is as follows: the calcination aid that has passed through a 100-mesh sieve is mixed with lithium-containing aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 900°C for 180 minutes to obtain calcined clinker.

[0120] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with water at a liquid-to-solid ratio of 3:1 to form a slurry, which was reacted at 60°C for 120 minutes. After the reaction, the mixture was filtered to obtain a water-leached solution and a water-leached residue. In this embodiment, the lithium leaching rate was 77.72%, the fluorine leaching rate was 0.006%, and the aluminum leaching rate was 0.0015% during the water leaching stage. The water-leached residue was mixed with an acid leaching solution with a pH of 2.5 at a liquid-to-solid ratio of 3:1 and reacted at 60°C for 90 minutes. The pH of the slurry was controlled between 2.5 and 0.1 during the reaction to obtain a leachate and a leachate residue. In this embodiment, the total lithium leaching rate was 99.15%, the fluorine leaching rate was 1.31%, and the aluminum leaching rate was 0.04%.

[0121] Example 18

[0122] In this embodiment, the roasting aid for lithium-aluminum electrolyte waste is a mixture of calcium sulfate, calcium carbonate, and calcium hydroxide. The molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 3:1, and the molar ratio of calcium sulfate, calcium carbonate, and calcium hydroxide is 1:1:1.

[0123] The application method of the calcination aid in the resource utilization of lithium-aluminum electrolyte waste in this embodiment is as follows: calcium-containing material that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte powder, the mixture is placed in a calcination furnace, the furnace door is closed, and calcination is carried out at 850°C for 120 minutes to obtain calcined clinker.

[0124] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with water at a liquid-to-solid ratio of 4:1 to form a slurry, which was reacted at 50°C for 90 minutes. After the reaction, the mixture was filtered to obtain a water-leached solution and a water-leached residue. In this embodiment, the lithium leaching rate was 81.72%, the fluorine leaching rate was 0.005%, and the aluminum leaching rate was 0.0011% during the water leaching stage. The water-leached residue was mixed with an acid leaching solution with a pH of 2.5 at a liquid-to-solid ratio of 3:1 and reacted at 75°C for 90 minutes. The pH of the slurry was controlled between 2.3 and 0.1 during the reaction to obtain a leachate and a leachate residue. In this embodiment, the total lithium leaching rate was 99.35%, the fluorine leaching rate was 0.95%, and the aluminum leaching rate was 9.16%.

[0125] Comparative Example 1

[0126] The comparative example of lithium-aluminum electrolyte waste roasting aid is a mixture of calcium chloride and calcium hydroxide. The molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1, and the molar ratio of calcium chloride to calcium hydroxide is 1:1.

[0127] The calcination aid that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte powder. The mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 800℃ for 120 minutes to obtain calcined clinker.

[0128] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with pH 2.5 at a liquid-to-solid ratio of 3:1 and reacted at 60℃ for 120 minutes. The pH of the slurry was controlled between 2.5 and 0.5 during the reaction to obtain a leachate and a leaching residue. In this comparative example, the lithium leaching rate was 52.53%, the fluorine leaching rate was 0.48%, and the aluminum leaching rate was 24.18%.

[0129] As can be seen from this comparative example, not all combinations of different anionic calcium-containing compounds have excellent phase conversion effects of lithium-containing aluminum electrolytes. The calcium-containing composition in this comparative example not only fails to effectively promote the conversion of lithium-containing phases, but also, compared with the blank calcination of Comparative Example 8, inhibits lithium leaching to a certain extent, while promoting the leaching of the impurity element fluorine.

[0130] Comparative Example 2

[0131] The roasting aid for lithium-aluminum electrolyte waste in this comparative example is calcium carbonate.

[0132] Calcium carbonate that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte at a mass ratio of 1.5:1. The mixture is placed in a roasting furnace, the furnace door is closed, and roasted at 800℃ for 120 minutes to obtain roasted clinker.

[0133] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with pH 2.3 at a liquid-to-solid ratio of 3:1 and reacted at 60℃ for 90 minutes. The pH of the slurry was controlled between 2.3 and 0.2 during the reaction to obtain a leachate and leaching residue. In this comparative example, the lithium leaching rate was 71.79%, the fluorine leaching rate was 1.38%, and the aluminum leaching rate was 15.30%.

[0134] The lithium leaching rate and Figure 3 (XRD patterns of the roasted clinker before and after leaching in this comparative example) It can be seen that although the addition of calcium carbonate alone can achieve lithium conversion and leaching promotion to a certain extent, the lithium is mainly converted into the Li3AlF6 phase, which is different from the main lithium-containing phase in Example 1. The weak acid leaching can only leach out part of the lithium in this comparative example. Compared with Example 1, the lithium leaching rate is reduced by about 25 percentage points.

[0135] Comparative Example 3

[0136] The comparative example of lithium-aluminum electrolyte waste roasting aid is a mixture of calcium carbonate and calcium sulfate. The molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1, and the molar ratio of calcium carbonate to calcium sulfate is 1:1.

[0137] The calcination aid that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte powder. The mixture is placed in a calcination furnace, the furnace door is closed, and the calcined material is obtained by calcining at 600°C for 120 minutes.

[0138] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with pH 2.3 at a liquid-to-solid ratio of 3:1 and reacted at 60℃ for 90 minutes. The pH of the slurry was controlled within the range of 2.3 ± 0.2 during the reaction. After the reaction, the mixture was filtered to obtain a lithium-containing leaching solution and leaching residue. In this comparative example, the lithium leaching rate in the lithium-aluminum electrolyte was 67.60%, the fluorine leaching rate was 1.71%, and the aluminum leaching rate was 31.77%.

[0139] As can be seen from the lithium leaching rate in this comparative example, when the calcination aid is applied to the calcination of lithium-containing aluminum electrolyte, if the calcination temperature is too low, the lithium leaching rate will be low. Possible reasons include that the calcination temperature is too low, resulting in insufficient activation energy for the reaction of the lithium-containing phase, which makes the reaction unable to proceed effectively or unable to convert to the easily soluble phase.

[0140] Comparative Example 4

[0141] The calcination aid for lithium-aluminum electrolyte waste in this comparative example is a mixture of calcium carbonate and calcium sulfate. The molar ratio of calcium in the calcination aid to aluminum in the lithium-aluminum electrolyte is 2.5:1, and the molar ratio of calcium carbonate to calcium sulfate is 1:1.

[0142] Lithium-aluminum electrolyte powder that has passed through a 100-mesh sieve is mixed with a calcination aid. The mixture is placed in a calcination furnace, the furnace door is closed, and the mixture is calcined at 700°C for 120 minutes to obtain calcined clinker.

[0143] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with pH 2.3 at a liquid-to-solid ratio of 3:1 and reacted at 60℃ for 90 minutes. The pH of the slurry was controlled within the range of 2.3 ± 0.2 during the reaction. After the reaction, the mixture was filtered to obtain a lithium-containing leaching solution and leaching residue. In this comparative example, the lithium leaching rate in the lithium-aluminum electrolyte was 77.56%, the fluorine leaching rate was 1.71%, and the aluminum leaching rate was 53.66%.

[0144] The lithium leaching rate in this comparative example shows that when the calcination aid is applied to the calcination of lithium-containing aluminum electrolytes, compared with Comparative Example 3, further increasing the calcination temperature can improve the lithium leaching rate to a certain extent, but the leaching of aluminum also increases accordingly. This indicates that the conversion of lithium-containing and aluminum-containing phases is a multi-parallel process, not a single conversion process.

[0145] Comparative Example 5

[0146] The roasting aid for lithium-aluminum electrolyte waste in this comparative example is calcium sulfate.

[0147] Calcium sulfate that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte powder, wherein the molar ratio of calcium to aluminum in the lithium-aluminum electrolyte is 2.5:1. The mixture is placed in a roasting furnace, the furnace door is closed, and after roasting at 800℃ for 120 minutes, roasted clinker is obtained.

[0148] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with pH 2.3 at a liquid-to-solid ratio of 3:1 and reacted at 60℃ for 90 minutes. The pH of the slurry was controlled between 2.3 and 0.2 during the reaction to obtain a leachate and leaching residue. In this comparative example, the lithium leaching rate was 79.13%, the fluorine leaching rate was 0.10%, and the aluminum leaching rate was 38.13%.

[0149] As can be seen from this comparative example, adding calcium sulfate alone is also insufficient to achieve effective lithium leaching.

[0150] Comparative Example 6

[0151] The roasting aids for lithium-aluminum electrolyte waste in this comparative example are calcium hydroxide and calcium oxide. The molar ratio of calcium in the roasting aid to aluminum in the lithium-aluminum electrolyte is 2.5:1, and the molar ratio of calcium oxide to calcium hydroxide is 1:1.

[0152] The calcination aid that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte powder. The mixture is placed in a calcination furnace, the furnace door is closed, and after calcination at 800℃ for 120 minutes, calcined clinker is obtained.

[0153] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with a pH of 2.5 at a liquid-to-solid ratio of 3:1. The pH of the slurry was controlled between 2.5 and 0.5 during the reaction, and the mixture was reacted at 60°C for 90 minutes to obtain a leachate and leaching residue. In this comparative example, the lithium leaching rate was 73.22%, the fluorine leaching rate was 0.87%, and the aluminum leaching rate was 27.55%.

[0154] As can also be seen from this comparative example, not all combinations of different anionic calcium-containing compounds have excellent lithium fluorine-aluminum compound conversion effects.

[0155] Comparative Example 7

[0156] The roasting aids for lithium-aluminum electrolyte waste in this comparative example are calcium sulfate and calcium carbonate, wherein the molar ratio of calcium to aluminum in the lithium-aluminum electrolyte is 0.5:1, and the molar ratio of calcium sulfate to calcium carbonate is 1:1.

[0157] The calcination aid that has passed through a 100-mesh sieve is mixed with lithium-aluminum electrolyte powder. The mixture is placed in a calcination furnace, the furnace door is closed, and after calcination at 800℃ for 120 minutes, calcined clinker is obtained.

[0158] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with an acid leaching solution with pH 2.3 at a liquid-to-solid ratio of 3:1 and reacted at 60℃ for 90 minutes. The pH of the slurry was controlled between 2.3 and 0.2 during the reaction to obtain a leachate and leaching residue. In this comparative example, the lithium leaching rate was 67.38%, the fluorine leaching rate was 0.65%, and the aluminum leaching rate was 37.68%.

[0159] As can be seen from this comparative example, insufficient addition of calcium-containing additives cannot achieve efficient conversion promotion of lithium fluorine aluminum compounds.

[0160] Comparative Example 8

[0161] This comparative example does not use calcination aids.

[0162] Lithium-aluminum electrolyte powder that has passed through a 100-mesh sieve is placed in a roasting furnace, the furnace door is closed, and after roasting at 800℃ for 120 minutes, roasted clinker is obtained.

[0163] The calcined clinker was ground to pass through a 100-mesh sieve to obtain calcined powder. The calcined powder was then mixed with a leaching agent with a pH of 2.3 at a liquid-to-solid ratio of 3:1 and reacted at 60°C for 120 minutes. The pH of the leaching system was controlled between 2.3 and 0.1 to obtain leaching solution and leaching residue. In this comparative example, the lithium leaching rate was 55.88%, the fluorine leaching rate was 0.05%, and the aluminum leaching rate was 36.17%.

[0164] As can be seen from this comparative example, without the addition of calcium-containing additives, it is impossible to achieve efficient conversion promotion of lithium-containing phases.

[0165] Comparative Example 9

[0166] The lithium-aluminum electrolyte in this comparative example was not subjected to calcination treatment.

[0167] Lithium-aluminum electrolyte powder that has passed through a 100-mesh sieve was mixed with acid leaching solution at a liquid-to-solid ratio of 3:1, and the pH of the slurry was controlled within the range of 2.0±0.1 during the reaction. The reaction was carried out at 60℃ for 120 min. After the reaction was completed, the mixture was filtered to obtain lithium-containing leaching solution and leaching residue. The lithium leaching rate in the lithium-aluminum electrolyte of this comparative example was 7.23%.

[0168] As can be seen from this comparative example, without roasting treatment, effective lithium leaching cannot be achieved under weak acid conditions.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

[0170] Furthermore, those skilled in the art will understand that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and form different embodiments. For example, in the foregoing claims, any of the claimed embodiments can be used in any combination. The information disclosed in this background section is intended only to enhance the understanding of the general background of this application and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

Claims

1. A lithium-containing aluminum electrolyte scrap roasting aid characterized by, The calcination aid contains a first calcium-containing substance and a second calcium-containing substance. The first calcium-containing substance is at least one of calcium sulfate, calcium bisulfate, calcium carbonate, or calcium bicarbonate. The second calcium-containing substance is at least one of calcium carbonate, bicarbonate, sulfate, bisulfate, hydroxide, oxide, or chloride. The second calcium-containing substance contains anions that are different or dissimilar to the first calcium-containing substance. The calcium molar amount in the first calcium-containing substance accounts for 40%-80% of the total calcium molar amount in the calcination aid. The ratio of the total calcium molar amount of the first and second calcium-containing substances to the aluminum molar amount in the lithium-aluminum electrolyte waste is 1-4:

1.

2. The lithium-bearing aluminum electrolyte scrap calcination aid of claim 1, wherein, The calcium molar content in the first calcium-containing substance accounts for 50%-80% of the total calcium molar content in the calcination aid; And / or, the ratio of the total molar amount of calcium in the first calcium-containing substance and the second calcium-containing substance to the molar amount of aluminum in the lithium-aluminum electrolyte waste is 1.5-3.5:

1.

3. The lithium-bearing aluminum electrolyte scrap calcination aid of claim 2, wherein, The first calcium-containing substance is at least one of calcium sulfate or calcium hydrogen sulfate; And / or, the second calcium-containing substance is at least one of calcium oxide, hydroxide, carbonate, bicarbonate, and chloride; And / or, the molar amount of calcium in the first calcium-containing substance accounts for 60-75% of the total molar amount of calcium in the calcination aid; And / or, the ratio of the total molar amount of calcium in the first calcium-containing substance and the second calcium-containing substance to the molar amount of aluminum in the lithium-aluminum electrolyte waste is 2-3:

1.

4. Lithium-containing aluminium electrolyte scrap calcination aid according to any one of claims 1-3, characterised in that The first calcium-containing substance is calcium sulfate or calcium hydrogen sulfate; The second calcium-containing substance is calcium hydroxide and / or calcium oxide; or, the second calcium-containing substance is calcium carbonate and calcium chloride; or, the second calcium-containing substance is a combination of at least one of calcium hydroxide and calcium oxide with at least one of calcium chloride and calcium carbonate.

5. A process for the preparation of a lithium-containing aluminium electrolyte waste calcination aid according to any one of claims 1 to 4, characterised in that, Includes the following steps: Provide the first calcium-containing substance and the second calcium-containing substance; Based on the ratio of the calcium molar amount in the first calcium-containing substance to the total calcium molar amount in the roasting aid, the ratio of the total calcium molar amount of the first calcium-containing substance and the second calcium-containing substance to the aluminum molar amount in the lithium-aluminum electrolyte waste, and the aluminum molar amount in the lithium-aluminum electrolyte waste, the first calcium-containing substance and the second calcium-containing substance are prepared, and the prepared first calcium-containing substance and the second calcium-containing substance are mixed to obtain the lithium-aluminum electrolyte waste roasting aid.

6. The application of the lithium-containing aluminum electrolyte waste roasting aid as described in any one of claims 1-4 in the recycling of lithium-containing aluminum electrolyte waste.

7. A method for the use of a sintering aid in the recycling of lithium-containing aluminum electrolyte waste, characterized in that, Includes the following steps: The lithium-aluminum electrolyte waste is mixed with a roasting aid and then roasted, wherein the roasting aid is the roasting aid described in any one of claims 1-4.

8. The method for the use of the calcination aid according to claim 7 in the resource utilization of lithium-containing aluminum electrolyte waste, characterized in that, The roasting temperature is 750-1100℃; and / or the roasting time is 0.75-5h.

9. The method for the use of the calcination aid according to claim 8 in the resource utilization of lithium-containing aluminum electrolyte waste, characterized in that, The calcination temperature is 760-1050℃, more preferably 780-900℃; and / or the calcination time is 1-3h, more preferably 1-2h.

10. The roasted clinker obtained by the method of applying the roasting aid according to any one of claims 7-9 in the resource utilization of lithium-containing aluminum electrolyte waste.

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