Harmless disposal method of overhaul slag cooperating with spodumene

Abstract

The invention discloses an overhaul slag and spodumene synergistic harmless treatment method which comprises the following steps: putting aluminum-containing overhaul slag powder, spodumene powder and concentrated sulfuric acid into a roasting furnace, sequentially mixing and roasting at high temperature in a negative pressure environment to obtain roasting clinker containing aluminum oxide, and introducing HF gas generated in the mixing and high-temperature roasting processes into a calcium-containing solution to obtain calcium-containing clinker containing aluminum oxide; calcium fluoride is obtained; the temperature of high-temperature roasting is 1000 DEG C or above; slurrying the roasting clinker containing the aluminum oxide, adding a calcium-containing alkaline regulator, leaching, and carrying out solid-liquid separation to obtain a lithium-containing filtrate and slag containing the aluminum oxide; causticizing the lithium-containing filtrate, and removing impurities to obtain a purified lithium-containing solution; and evaporating and concentrating the purified lithium-containing solution to obtain a lithium-rich solution. Carbon contained in the overhaul slag is effectively utilized to provide a heat source, valuable substances contained in the overhaul slag and the overhaul slag are combined and converted into a high-value product, the whole process is simple, operation is easy and convenient, and no pollutant is generated.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling of hazardous solid waste, and relates to a method for the harmless disposal of overhaul slag in conjunction with spodumene. Background Technology

[0002] With the continuous development of the new energy industry, lithium carbonate, as a key raw material for lithium-ion battery cathode materials, is experiencing strong market demand and increasingly tight supply. Currently, lithium carbonate production mainly relies on two technical routes: lithium extraction from lithium ore and lithium extraction from salt lakes. However, lithium extraction from lithium ore is energy-intensive, while lithium extraction from salt lakes is limited by geographical environment and resource distribution, resulting in the overall production cost of lithium carbonate remaining high.

[0003] Electrolytic aluminum overhaul slag is a solid waste generated during the overhaul of aluminum electrolytic cells, mainly composed of approximately 55% waste cathode carbon blocks and 45% waste refractory materials. It is estimated that producing 1 ton of electrolytic aluminum generates 5-10 kg of waste cathode carbon blocks and 10-20 kg of waste refractory materials. In the electrolytic aluminum process, the addition of lithium fluoride as a flux enriches the overhaul slag with a certain amount of lithium and fluorine. Therefore, using it as a secondary lithium source to recover lithium carbonate can not only significantly reduce lithium extraction costs but also help alleviate the lithium resource shortage, demonstrating promising prospects for resource utilization.

[0004] Currently, research on lithium extraction technology from overhaul slag is insufficient, and related patents are relatively limited. Chinese patent CN105293536A discloses a lithium extraction process from electrolytic aluminum slag. This method, through steps such as acidification, water leaching, alkaline hydrolysis, causticization, and carbonization, ultimately produces battery-grade lithium carbonate, providing a new approach for lithium extraction from overhaul slag. However, it requires equipment with high resistance to fluorine corrosion and generates hazardous waste, posing a significant environmental risk. Another Chinese patent, CN1320491A, proposes a sulfuric acid method for treating electrolytic aluminum slag, which can recover multiple valuable elements and theoretically has the potential for clean production, but it does not address the specific lithium extraction method. In summary, while acid treatment offers a high lithium recovery rate, the acidification stage easily generates hydrofluoric acid, which severely corrodes the reaction equipment, limiting its practical application. Chinese patent CN115216645A discloses a mixed salt calcination method for extracting lithium from electrolytic aluminum slag, but this method does not properly address cyanide pollution, and the alkaline leaching process leads to the dissolution of large amounts of aluminum, increasing the difficulty of subsequent separation. In the spodumene acid method for lithium extraction, such as the lithium extraction method disclosed in Chinese patent CN101948124A, lithium is extracted by transforming crystal roasting and acid roasting. The process is very complicated, requires a large investment in equipment, and requires two high-temperature roasting processes.

[0005] In contrast, although lithium extraction technology from spodumene is relatively mature, it still has obvious drawbacks. For example, Chinese patent CN105071811A uses a sulfuric acid pressure cooking method after crystallization roasting, which simplifies the process and reduces energy consumption to some extent, but the utilization rate of sulfuric acid is low and the acid consumption is large, so the economic efficiency and environmental protection are still not ideal.

[0006] In summary, existing lithium extraction technologies from overhaul slag still suffer from problems such as immature processes, high equipment requirements, significant risks of secondary pollution, and high energy consumption. Therefore, it is necessary to develop a new lithium extraction method that is simple, economical, efficient, environmentally friendly, and capable of achieving the co-processing and harmless disposal of overhaul slag, drawing on experience in lithium extraction from spodumene. Summary of the Invention

[0007] To address the aforementioned problems in the existing technology, the purpose of this invention is to provide a method for the harmless disposal of overhaul slag and spodumene. This method avoids the influence of aluminum ions in the impurity removal and purification process through high-temperature roasting, thereby achieving the extraction and recovery of lithium from hazardous waste overhaul slag and spodumene. Furthermore, the high-temperature roasting process also achieves the degradation of cyanide in the overhaul slag.

[0008] To achieve the above-mentioned technical objectives, the present invention provides a method for the harmless disposal of overhaul slag in conjunction with spodumene, comprising the following steps:

[0009] S1 Aluminum-containing overhaul slag powder and spodumene powder are placed in a roasting furnace and mixed and roasted at high temperature under negative pressure to obtain roasted clinker containing aluminum oxide. The HF gas generated during the mixing and high-temperature roasting process is passed into a calcium-containing solution to obtain calcium fluoride. The high-temperature roasting temperature is above 1000℃.

[0010] S2 involves slurrying the calcined clinker containing aluminum oxides, adding a calcium-containing alkaline regulator, and then leaching and separating the solid and liquid components to obtain lithium-containing filtrate and aluminum oxide-containing slag.

[0011] The lithium-containing filtrate described in S3 is causticized and then purified to obtain a purified lithium-containing solution.

[0012] The purified lithium-containing solution described in S4 is then evaporated and concentrated to obtain a lithium-rich solution with a lithium concentration ≥12g / L.

[0013] The key innovation of this invention lies in the use of high-temperature roasting, which allows aluminum to remain indirectly in the slag as aluminum oxide. This simplifies the removal of metal cations during leaching and avoids the adverse effects of aluminum ions on lithium purification, resulting in a harmless high-concentration lithium-rich solution. Specifically, during the mixing of aluminum slag powder and spodumene powder with concentrated sulfuric acid, fluorides in the slag are collected as hydrogen fluoride in the flue gas and further precipitated as calcium fluoride, achieving resource recovery of fluorine. Cyanide is also oxidized and decomposed by concentrated sulfuric acid during stirring. As the roasting temperature increases, aluminum compounds in the slag and spodumene are first converted into aluminum sulfate, and further decomposed into aluminum oxides (including alumina) upon reaching the roasting temperature of this invention. Simultaneously, lithium in the slag and spodumene is converted into soluble lithium sulfate. The subsequently added calcium-containing alkaline regulator can preferentially remove some impurity metal cations to a certain extent, reducing the reagent consumption for subsequent fine purification. Furthermore, it can effectively remove residual sulfate ions in the solution by combining with them to form calcium sulfate, preventing sulfate and sodium ions from precipitating as saturated sodium sulfate crystals during the subsequent preparation of lithium carbonate from the lithium-rich solution, thus avoiding a decrease in the purity of lithium carbonate. The causticization process converts lithium sulfate into lithium hydroxide solution and calcium sulfate precipitate; further purification removes excess calcium ions introduced into the lithium hydroxide solution and removes metal cations such as aluminum, iron, and magnesium from the solution, resulting in a pure lithium-containing solution. Thanks to steps S1 to S3, a high-concentration, pure lithium-rich solution can be obtained through final enrichment.

[0014] Experiments have shown that controlling the roasting temperature in step S1 of this invention is crucial for the entire impurity removal process. If the roasting temperature is too low, the aluminum in the overhaul slag and spodumene will be converted into soluble aluminum sulfate. In the subsequent leaching process, aluminum sulfate will enter the leaching solution along with lithium ions. At the same time, small amounts of impurity metal ions such as iron, magnesium, and calcium will also enter the leaching solution, making lithium purification very difficult. If hydroxide ions are added, the resulting Al(OH)3 colloid has high adsorption capacity, causing a significant loss of lithium ions. Furthermore, high-temperature roasting can convert the alumina crystalline phase in the aluminum oxide-containing slag into α-Al2O3, making the slag phase more suitable for making refractory materials.

[0015] As a preferred embodiment, the aluminum-containing overhaul slag powder and spodumene powder have a particle size of -2mm or more, accounting for more than 90%. Furthermore, the overhaul slag and spodumene are each crushed and passed through a 2mm sieve, and the material remaining on the sieve is recycled back to the crushing process for further crushing.

[0016] As a preferred embodiment, the mass ratio of the aluminum-containing overhaul slag powder and spodumene powder to concentrated sulfuric acid is (100~80):(25~35):(120~140). In this invention, excessive use of overhaul slag, due to its presence of metallic impurities, fluorides, and cyanides, increases the burden on flue gas treatment and the consumption of oxidative decomposition reagents. Furthermore, it leads to excessive carbon source consumption and resource waste. Spodumene powder, on the other hand, is primarily used in the process to provide a suitable amount of lithium source.

[0017] As a preferred embodiment, in S1, the mixing time is 5-10 min; the high-temperature calcination temperature is 1000-1200℃, the heating rate is 3-10℃ / min, the calcination time is 1-3 h, and the exhaust gas generated during calcination is introduced into a calcium hydroxide solution with a concentration of 5-10 mol / L.

[0018] As a preferred embodiment, in S2, the calcium-containing alkaline regulator includes at least one of calcium oxide and calcium hydroxide, and the amount used is 20-30 wt% of the calcined clinker containing aluminum oxide. This invention achieves a triple effect by adding a calcium-containing alkaline regulator: removing impurity metal cations, removing calcium, and adjusting the pH of the system to 8-10.

[0019] As a preferred embodiment, the leaching conditions are as follows: with water as the leaching agent, the liquid-to-solid ratio is controlled at 4-12, the leaching temperature is 25-65℃, and the leaching time is 2-4 h.

[0020] As a preferred embodiment, the causticization process involves adding calcium hydroxide and quicklime to adjust the pH to 9-10.

[0021] As a preferred embodiment, the impurity removal includes carbonate removal and hydrolysis.

[0022] Furthermore, after causticization, the solution can be filtered, and sodium hydroxide can be added to the filtrate to adjust the concentration to 11-12 to remove some of the metal cations.

[0023] As a preferred embodiment, during the carbonate purification process, sodium carbonate is added at a molar ratio of carbonate to calcium ions of (1.4~1.6):1. The main purpose of carbonate purification is to remove calcium ions introduced during the causticizing process as calcium sulfate precipitate; therefore, an excess of carbonate ions is required to ensure complete calcium ion precipitation.

[0024] As a preferred embodiment, during the hydrolysis process, after adjusting the solution pH to 5-6, a complexing agent is added, and the solution pH is gradually increased until the solution becomes clear. The hydrolysis process of this invention primarily aims to remove metallic impurity cations such as aluminum, iron, and magnesium from the solution. Therefore, it is necessary to first adjust the pH to a lower range, using the complexing agent to convert lithium ions into water-soluble complexes, and then gradually increase the pH to 13, gradually causing the metallic impurity cations to hydrolyze and precipitate. Further, sulfuric acid is added to adjust the pH to 5-6.

[0025] As a preferred embodiment, the complexing agent is one of EDTA and oxalic acid. EDTA is more preferably used. The present invention uses EDTA as a complexing agent to rapidly form a stable complex with lithium ions, preventing precipitation.

[0026] As a preferred embodiment, lithium carbonate is prepared by adding carbonate to the lithium-rich solution.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) This invention utilizes the carbon contained in the hazardous waste overhaul residue and spodumene for synergistic sulfation roasting, which can effectively provide a heat source by combining the valuable substances contained in the overhaul residue and transforming them into high-value products. The whole process is simple, easy to operate, and produces no pollutants.

[0029] (2) This invention not only solves the environmental hazards of overhaul slag, but also achieves economic benefits and has certain industrial application prospects.

[0030] (3) This invention provides a new approach to synergistic lithium extraction and impurity removal from overhaul slag and spodumene. By using high-temperature roasting, aluminum is indirectly retained in the slag in the form of aluminum oxide. This simplifies the removal of metal cations during leaching and avoids the adverse effects of aluminum ions on lithium purification, thus enabling the production of a high-concentration lithium-rich solution without harm.

[0031] (4) This invention converts the fluoride in the overhaul slag into calcium fluoride and decomposes the cyanide in the overhaul slag, thus achieving true harmless treatment.

[0032] (5) The high-temperature roasting of the present invention is beneficial to obtaining aluminum oxide slag with better crystal structure, which can then be further used as a refractory material. Attached Figure Description

[0033] Figure 1 The present invention provides a process flow diagram for a method of harmless treatment of overhaul slag and spodumene, wherein the impurity removal includes primary impurity removal and secondary impurity removal, and the high-lithium solution is a lithium-rich solution. Detailed Implementation

[0034] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments are merely illustrative of the present invention and should not be considered as specific limitations thereof. Unless otherwise specified, the relevant percentages refer to mass percentages.

[0035] The overhaul slag in the examples and comparative examples refers to the overhaul slag of electrolytic aluminum, the main components of which are shown in Table 1, and the main components of spodumene are shown in Table 2.

[0036]

[0037]

[0038] Pretreatment: The overhaul slag and spodumene are subjected to a crushing-screening process, with a 2mm sieve for screening. The material on the sieve is returned to the crushing process, and finally, the material with a particle size of less than 2mm (100%) is obtained. The overhaul slag contains 100mg / kg of cyanide.

[0039] Example 1

[0040] A method for the harmless treatment of overhaul slag in conjunction with spodumene, according to... Figure 1 The process flow shown includes the following steps:

[0041] S1 uses overhaul slag from an electrolytic aluminum plant in Henan and spodumene mined from a lithium mine in Hunan as raw materials. 100g of pretreated overhaul slag, 35g of spodumene, and 140g of concentrated sulfuric acid are placed in a roasting furnace and stirred for 5 minutes under negative pressure to ensure uniform mixing. The temperature is increased to 1000℃ at a rate of 5℃ / min and roasted for 2 hours to obtain roasted clinker containing aluminum oxides. The HF tail gas generated during roasting is passed into a 5mol / L calcium hydroxide solution to obtain calcium fluoride. The HF recovery rate reaches 99.4%.

[0042] After the S2 roasting process is completed, the roasted clinker containing aluminum oxide is transferred to a mechanically stirred tank for slurrying and leaching. The liquid-to-solid ratio is controlled at 12 g / mL, the leaching temperature is 65℃, and the leaching time is 3 hours. Simultaneously, 20 wt% calcium hydroxide and 20 wt% calcium oxide (relative to the slurry, mass ratio 1:1) are added and mixed. After solid-liquid separation, lithium-containing filtrate and aluminum oxide-containing slag are obtained. The aluminum oxide-containing slag (crystalline phase α-Al2O3) is further utilized as a refractory material.

[0043] S3 first added 10g of calcium hydroxide and 15g of quicklime to the lithium-containing filtrate to adjust the pH to 10. After filtration using a plate and frame filter press, sodium hydroxide was added to adjust the pH to 12, and the solution was filtered again. Sodium carbonate was added at a carbonate:calcium ion molar ratio of 1.5:1 to remove calcium. After calcium removal, sulfuric acid was added to adjust the pH to 6. EDTA was then added, and the pH of the solution was gradually increased to approximately 12 until the solution became clear. The concentrations of aluminum, calcium, magnesium, and fluoride ions in the solution were measured to be less than 200 ppm, indicating a purified lithium-containing solution with a lithium recovery rate of 99%.

[0044] S4 evaporates and concentrates the purified liquid, and the lithium in the solution is concentrated and enriched, eventually making the lithium in the lithium-rich solution reach 12g / L.

[0045] S5 slowly adds the obtained lithium-rich solution dropwise into a 30wt% sodium carbonate stirred hydrothermal solution to obtain a lithium carbonate product with a purity of 99.4%.

[0046] Example 2

[0047] A method for the harmless treatment of overhaul slag in conjunction with spodumene, according to... Figure 1 The process flow shown includes the following steps:

[0048] S1 uses overhaul slag from an electrolytic aluminum plant in Henan and spodumene mined from a lithium mine in Hunan as raw materials. 80g of pretreated overhaul slag, 25g of spodumene, and 130g of concentrated sulfuric acid are placed in a roasting furnace and stirred for 5 minutes under negative pressure to ensure uniform mixing. The temperature is increased to 1100℃ at 3℃ / min and roasted for 1 hour to obtain roasted clinker containing aluminum oxide. The HF tail gas generated during roasting is passed into a 5mol / L calcium hydroxide solution to obtain calcium fluoride. The HF recovery rate reaches 99.5%.

[0049] After the S2 roasting process is completed, the roasted clinker containing aluminum oxide is transported to a mechanically stirred tank for slurrying and leaching. The liquid-to-solid ratio is controlled at 10 g / mL, the leaching temperature is 45℃, and the leaching time is 2 hours. At the same time, 30 wt% calcium hydroxide and 30 wt% calcium oxide (relative to the amount of slurry, mass ratio of 1:1) are added and mixed. After solid-liquid separation, lithium-containing filtrate and aluminum oxide-containing slag are obtained. The aluminum oxide-containing slag (crystal phase α-Al2O3) is further utilized as a refractory material.

[0050] S3 first added 12g of calcium hydroxide and 12g of quicklime to the lithium-containing filtrate to adjust the pH to 10. After filtration using a plate and frame filter press, sodium hydroxide was added to adjust the pH to 13, and the solution was filtered again. Sodium carbonate was added at a carbonate:calcium ion molar ratio of 1.4:1 to remove calcium. After calcium removal, sulfuric acid was added to adjust the pH to 5.5. EDTA was then added, and the pH of the solution was gradually increased to approximately 13 until the solution became clear. The concentrations of aluminum, calcium, magnesium, and fluoride ions in the solution were measured to be less than 100 ppm, indicating a purified lithium-containing solution with a lithium recovery rate of 98.8%.

[0051] S4 evaporates and concentrates the purified liquid, and the lithium in the solution is concentrated and enriched, eventually making the lithium in the lithium-rich solution reach 15g / L.

[0052] S5 slowly adds the obtained lithium-rich solution dropwise into a 35wt% sodium carbonate stirred hydrothermal solution to obtain a lithium carbonate product with a purity of 99.2%.

[0053] Example 3

[0054] A method for the harmless treatment of overhaul slag in conjunction with spodumene, according to... Figure 1 The process flow shown includes the following steps:

[0055] S1 uses overhaul slag from an electrolytic aluminum plant in Henan and spodumene mined from a lithium mine in Hunan as raw materials. 90g of pretreated overhaul slag, 30g of spodumene, and 140g of concentrated sulfuric acid are placed in a roasting furnace and stirred for 5 minutes under negative pressure to ensure uniform mixing. The temperature is increased to 1200℃ at 10℃ / min and roasted for 3 hours to obtain roasted clinker containing aluminum oxides. The HF tail gas generated during roasting is passed into a 5mol / L calcium hydroxide solution to obtain calcium fluoride. The HF recovery rate reaches 99.1%.

[0056] After the S2 roasting process is completed, the roasted clinker containing aluminum oxide is transferred to a mechanically stirred tank for slurry leaching. The liquid-to-solid ratio is controlled at 4 g / mL, the leaching temperature is 25℃, and the leaching time is 4 hours. Simultaneously, a mixture of 30 wt% calcium hydroxide and 30 wt% calcium oxide (mass ratio 1:1) (relative to the amount of slurry) is added and stirred. After solid-liquid separation, lithium-containing filtrate and aluminum oxide-containing slag are obtained. The aluminum oxide-containing slag (crystalline phase α-Al2O3) is further utilized as a refractory material.

[0057] S3 first added 8g of calcium hydroxide and 18g of quicklime to the lithium-containing filtrate to adjust the pH to 11. After filtration through a plate and frame filter press, sodium hydroxide was added to adjust the pH to 13, and the solution was filtered again. Sodium carbonate was added at a carbonate:calcium ion molar ratio of 1.6:1 to remove calcium. After calcium removal, sulfuric acid was added to adjust the pH to 5. EDTA was added, and the pH of the solution was gradually increased to approximately 13 until the solution became clear. The concentrations of aluminum, calcium, magnesium, and fluoride ions in the solution were measured to be less than 300 ppm, indicating a purified lithium-containing solution with a lithium recovery rate of 98.8%.

[0058] S4 evaporates and concentrates the purified liquid, and the lithium in the solution is concentrated and enriched, eventually making the lithium in the lithium-rich solution reach 13g / L.

[0059] S5 slowly adds the obtained lithium-rich solution dropwise into a 40wt% sodium carbonate stirred hydrothermal solution to obtain a lithium carbonate product with a purity of 99.0%.

[0060] Comparative Example 1

[0061] The only difference between this comparative example and Example 1 is that the high-temperature roasting temperature in S1 was changed to 600°C. The experiment found that in the S2 impurity removal step, since aluminum sulfate also entered the leaching solution, Al(OH)3 colloid was formed during the separation and impurity removal process. The concentrations of aluminum, calcium, magnesium and fluoride ions in the purified lithium-containing solution were 3 g / L, 1 g / L, 0.5 g / L and 0.1 g / L, respectively, resulting in a lithium recovery rate of only 75%.

[0062] Comparative Example 2

[0063] The only difference between this comparative example and Example 1 is that an equal amount of sodium hydroxide was used instead of calcium oxide in S2; all other steps and conditions were the same. The results showed that the amount of EDTA added in S4 was twice that of Example 1, and during the preparation of lithium carbonate from the lithium-rich solution in S5, sulfate and sodium ions precipitated as saturated sodium sulfate crystals, resulting in lithium carbonate with a purity of only 85%.

Claims

1. A method for the harmless disposal of overhaul slag in conjunction with spodumene, characterized in that: Includes the following steps: S1 Aluminum-containing overhaul slag powder and spodumene powder are placed in a roasting furnace and mixed and roasted at high temperature under negative pressure to obtain roasted clinker containing aluminum oxide. The HF gas generated during the mixing and high-temperature roasting process is passed into a calcium-containing solution to obtain calcium fluoride. The high-temperature roasting temperature is above 1000℃. S2 involves slurrying the calcined clinker containing aluminum oxides, adding a calcium-containing alkaline regulator, and then leaching and separating the solid and liquid components to obtain lithium-containing filtrate and aluminum oxide-containing slag. The lithium-containing filtrate described in S3 is causticized and then purified to obtain a purified lithium-containing solution. The purified lithium-containing solution described in S4 is then evaporated and concentrated to obtain a lithium-rich solution with a lithium concentration ≥12g / L.

2. The method for harmless disposal of overhaul slag and spodumene according to claim 1, characterized in that: The aluminum-containing overhaul slag powder and spodumene powder have a particle size of -2mm and a mass ratio of over 90%.

3. A method for the harmless treatment of overhaul slag and spodumene according to claim 1 or 2, characterized in that: The mass ratio of the aluminum-containing overhaul slag powder and spodumene powder to concentrated sulfuric acid is (100~80):(25~35):(120~140). In S1, the mixing time is 5-10 min; the high-temperature calcination temperature is 1000-1200℃, the heating rate is 3-10℃ / min, the calcination time is 1-3 h, and the tail gas produced by calcination is passed into a calcium hydroxide solution with a concentration of 5-10 mol / L.

4. The method for harmless disposal of overhaul slag and spodumene according to claim 3, characterized in that: In S2, the calcium-containing alkaline regulator includes at least one of calcium oxide and calcium hydroxide.

5. The method for harmless disposal of overhaul slag and spodumene according to claim 1, characterized in that: The leaching conditions are as follows: with water as the leaching agent, the liquid-to-solid ratio is controlled at 4~12 g / mL, the leaching temperature is 25~65℃, and the leaching time is 2~4 h.

6. A method for the harmless disposal of overhaul slag in conjunction with spodumene, as described in claim 1 or 5, characterized in that: The causticization process involves adding calcium hydroxide and quicklime to adjust the pH to 9-10.

7. The method for harmless disposal of overhaul slag and spodumene according to claim 1, characterized in that: The impurity removal includes carbonate removal and hydrolysis.

8. The method for harmless disposal of overhaul slag and spodumene according to claim 7, characterized in that: During the carbonate purification process, sodium carbonate is added at a molar ratio of carbonate to calcium ions of 1.4 to 1.6:

1. During the process of decontamination by water, the solution pH is adjusted to 5-6, a complexing agent is added, and the solution pH is gradually increased until the solution becomes clear.

9. The method for harmless disposal of overhaul slag and spodumene according to claim 8, characterized in that: The complexing agent is one of EDTA and oxalic acid.

10. The method for harmless disposal of overhaul slag and spodumene according to claim 9, characterized in that: Lithium carbonate is prepared by adding carbonate to the lithium-rich solution.

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