Secondary lithium extraction and resource utilization method of lithium extraction slag

Abstract

The invention belongs to the field of lithium slag treatment, and particularly relates to a secondary lithium extraction method of lithium extraction slag, which comprises the following steps: mixing and ball-milling the lithium extraction slag and a copper-based additive, and then carrying out water leaching treatment and solid-liquid separation to obtain lithium liquid and secondary lithium extraction slag; the copper-based auxiliary agent comprises at least one of copper sulfate, copper chloride and copper nitrate. In addition, the invention also comprises application of the secondary lithium extraction slag in concrete preparation. According to the method disclosed by the invention, the copper-based auxiliary agent is creatively adopted to carry out ball-milling auxiliary modification treatment on the lithium extraction slag, so that the secondary extraction effect of deeply embedded lithium in the lithium extraction slag can be accidentally improved, and a good lithium extraction effect can be obtained without high-temperature treatment conditions such as roasting and the like; and the physical and chemical characteristics of the secondary lithium extraction slag can be further optimized, so that the secondary lithium extraction slag can accidentally obtain excellent performance in the aspect of resource application of concrete. For example, the wear resistance, the breaking strength and the compressive strength of the concrete prepared by recycling the secondary lithium extraction slag can be improved.

Description

Technical Field

[0001] The present invention belongs to the field of solid waste resource utilization, and particularly relates to the field of secondary utilization of lithium extraction slag. Background Art

[0002] With the rapid rise of new energy storage industries, represented by lithium batteries, the lithium extraction industry, including lithium carbonate, lithium hydroxide, and lithium chloride, has experienced significant growth. However, the production of lithium slag, a residual product from industrial smelting, has increased annually. Lithium slag is an industrial solid waste generated during the lithium extraction process. Currently, the most common methods for lithium extraction include sulfuric acid roasting, limestone roasting, salt roasting, and high-temperature chloroform roasting. Typically, every ton of lithium salt produced generates 10 to 50 tons of lithium slag, resulting in an annual stockpile of tens of millions of tons.

[0003] Lithium extraction slag generates large quantities of waste and has low resource utilization, leading to its primary storage. This not only occupies significant land resources but also requires high construction and maintenance costs. The accumulation of lithium slag results in significant land waste and environmental pollution, making its rational utilization a major challenge facing industrial development and upgrading.

[0004] Prior art also provides some methods for utilizing lithium slag. For example, Chinese Patent Publication No. CN116770098A discloses a method for acid leaching clay-type lithium ore with sulfuric acid and ammonium sulfate, followed by high-temperature lithium extraction. The method involves mixing the clay-type lithium ore with sulfuric acid, slurrying the mixture, reacting the residue with ammonium sulfate, and then dissolving the mixture at high temperature to produce a lithium-aluminum leachate. Chinese Patent Publication No. CN116065038A discloses a method for acid leaching with concentrated sulfuric acid followed by high-temperature lithium extraction. This method involves reacting a lithium-containing material with concentrated sulfuric acid, then calcining it at high temperature, and repeating this process to produce a lithium-containing leachate. Chinese Patent Publication No. CN119194106A discloses a method for efficiently extracting lithium carbonate from clay-type lithium ore using a selective adsorption process. The method specifically describes crushing and finely grinding the clay-type lithium ore to produce a powdered clay-type lithium ore; calcining the powdered clay-type lithium ore at high temperature to produce a calcined product; and leaching the calcined product with a dilute acid solution. This calcined product is then separated to produce a leachate and high-silicon slag, which is then used as a raw material for cement production.

[0005] Chinese patent document CN118290058A discloses a method for harmless resource recovery of lithium slag, comprising the following steps: S1: mixing lithium slag with a sulfuric acid-containing material to obtain a slurry mixture; S2: roasting the slurry mixture at a temperature of 180-750°C to obtain roasted slag, which is then soaked in water and filtered to obtain leached slag and leaching liquid; S3: drying the leached slag, adding an alkaline substance, and then ball-milling the mixture, and using the ball-milled mixture as a cement admixture.

[0006] In summary, it is difficult to extract lithium from the lithium slag for the second time after lithium extraction. Most of the industry needs to use high-temperature treatment methods, which can achieve a certain secondary lithium extraction effect, but it will also increase the composition. In addition, it may also affect its performance in cement mixture applications. Summary of the Invention

[0007] In view of the difficulty of secondary mild lithium extraction from existing lithium extraction slag, the first purpose of the present invention is to provide a secondary lithium extraction method for lithium extraction slag, aiming to gently achieve secondary lithium extraction from lithium extraction slag and obtain secondary lithium extraction slag that is beneficial to the performance of cement mixture.

[0008] The second object of the present invention is to provide a method for secondary lithium extraction and resource utilization of lithium extraction slag, aiming to use the slag after secondary lithium extraction for the preparation of high-performance concrete slurry and / or concrete.

[0009] Lithium extraction slag is the residue left after lithium extraction from lithium ore, such as lepidolite. Its lithium content is low, and the lithium is deeply embedded in the slag phase, making secondary lithium extraction extremely difficult. To address this issue, the conventional solution in the industry is to use high-temperature transformation and relatively intense leaching conditions. While this can achieve good secondary lithium extraction results, it also affects the slag phase and slag shape, making it unfavorable for its application in concrete and the performance of concrete prepared from resource-based materials. To address this issue, the present invention, after in-depth research, provides the following improvement scheme:

[0010] A secondary lithium extraction method for lithium extraction slag comprises mixing the lithium extraction slag and a copper-based additive and ball milling the mixture, followed by water immersion treatment and solid-liquid separation to obtain a lithium solution and secondary lithium extraction slag;

[0011] The copper-based additive includes at least one of copper sulfate, copper chloride and copper nitrate.

[0012] To address the difficulties in gentle secondary lithium extraction from lithium-extraction slag and the unsatisfactory performance of secondary lithium-extraction slag in concrete, the present invention innovatively uses copper-based additives to perform ball-milling-assisted modification on the lithium-extraction slag. This unexpectedly improves the secondary extraction of deeply embedded lithium in the lithium-extraction slag, enabling it to achieve good lithium extraction results without the need for high-temperature treatment such as roasting. Furthermore, the physicochemical characteristics of the secondary lithium-extraction slag can be further optimized, resulting in unexpectedly excellent performance in the resource utilization of concrete. For example, the wear resistance, flexural strength, and compressive strength of concrete prepared from the resource utilization of secondary lithium-extraction slag can be improved.

[0013] In the present invention, the lithium extraction slag can be any slag after lithium extraction, such as the lithium extraction slag after wet and pyrometallurgical lithium extraction of lepidolite. As an optional solution, it can be the leaching slag after lithium extraction from lepidolite concentrate by sulfate roasting.

[0014] In the present invention, the lithium extraction slag includes at least one phase of aluminophosphate silicate, leucite and sodalite.

[0015] In the present invention, the lithium content in the lithium extraction slag is 0.2-0.5 wt.%, and the SiO2 content is 20-35 wt.%. , CaO content is 10~30 wt.%, Al2O3 content is 8~10 wt.%, and Fe2O3 content is 0.8~2.7 wt.%.

[0016] Preferably, the copper-based additive is at least one of copper sulfate and copper chloride. Studies have shown that the preferred copper-based additive can be combined with the process to further improve the secondary lithium extraction effect of the lithium extraction slag and the concrete utilization performance of the secondary lithium extraction slag.

[0017] In the present invention, the copper-based additive comprises 0.5-3% of the weight of the lithium-extraction slag, for example, 0.5-2%, preferably 0.8-1.2%, and more preferably 0.9-1.1%. Research in the present invention has shown that this preferred ratio further improves the modification effect, helping to further enhance lithium leaching and the subsequent application performance of the secondary lithium-extraction slag in concrete.

[0018] In the present invention, the ball milling speed can be, for example, 200-500 rpm, preferably 300-400 rpm. Studies have found that at this optimal ball milling speed, good secondary lithium extraction from the lithium-extraction slag can be achieved. Furthermore, this speed facilitates the physicochemical changes in the secondary lithium-extraction slag, improving its performance in concrete.

[0019] The ball-to-material ratio (weight ratio of grinding balls to lithium-extraction slag) during ball milling can be 1-10:1, further 2-5:1, and more preferably 2.5-3.5:1. Research has found that optimal ball-to-material ratios achieve excellent secondary lithium extraction from the lithium-extraction slag. Furthermore, these ratios facilitate the physicochemical transformation of the secondary lithium-extraction slag, improving its performance in concrete.

[0020] Preferably, the ball milling time is 1 to 10 min, and further can be 4 to 6 min.

[0021] In the present invention, the ball milling is dry ball milling.

[0022] In the present invention, the liquid-to-solid ratio of the water immersion process is 2-10:1 (ml / g), and can further be 2.5-3.5 (ml / g); the process of the present invention can achieve effective lithium extraction at a high solid-to-liquid ratio.

[0023] Preferably, the temperature during the water immersion process is 10-40°C, and further can be 15-25°C.

[0024] Preferably, the immersion time is 0.5 to 5 h, and can further be 1 to 3 h. Considering efficiency, it can further be 1 to 1.5 h.

[0025] In the present invention, the lithium solution is directly subjected to lithium precipitation treatment, or the lithium solution is enriched and concentrated before being subjected to lithium precipitation treatment to obtain a lithium product.

[0026] In the present invention, the lithium precipitation and lithium enrichment methods can be conventional.

[0027] For example, as an optional solution, the present invention can pre-use ferrophosphorus slag, dolomite or zeolite as an adsorbent to adsorb lithium, and then undergo acid elution to obtain a lithium concentrate. The lithium concentrate is first subjected to conventional impurity removal and then to lithium precipitation treatment to obtain the lithium product.

[0028] The present invention also provides a method for secondary lithium extraction and resource utilization of lithium extraction slag, wherein the lithium extraction slag is treated by the secondary lithium extraction method of the present invention to obtain secondary lithium extraction slag; the secondary lithium extraction slag is used as an additive to prepare concrete slurry and / or concrete.

[0029] Research in the present invention shows that the secondary lithium extraction process described in the present invention can not only achieve secondary gentle extraction of lithium, but also optimize the physical and chemical characteristics of the slag, help adapt to the resource application requirements of concrete, and obtain better concrete performance.

[0030] In the application of the present invention, secondary lithium extraction slag, cement and aggregate are slurried with water to prepare concrete slurry.

[0031] In the application of the present invention, the water content in the concrete slurry is 100-200 kg / m 3 , cement dosage is 200~300 kg / m 3 The amount of secondary lithium extraction slag is 20~100 kg / m 3 The amount of aggregate is 1500~2000 kg / m 3 The aggregates include sand and gravel. Preferably, the total amount of cement and secondary lithium extraction slag is 250-350 kg / m 3 Among them, the proportion of secondary lithium extraction slag in (cement and secondary lithium extraction slag) is 10~30 wt.%, further 15~25 wt.%.

[0032] Furthermore, in the concrete slurry, water 160±10 kg / m 3 , the total amount of cement-secondary lithium extraction slag is 300±20kg / m 3 、Sand 750±30 kg / m 3 、Crushed stone 1120±50 kg / m 3The content of secondary lithium slag in cement-secondary lithium slag is 15-25 wt.%. Studies have shown that a better secondary lithium slag modification effect can be achieved under the optimal ratio.

[0033] In the application of the present invention, the concrete slurry is solidified to obtain concrete.

[0034] Beneficial effects

[0035] This invention innovatively uses a copper-based additive to perform ball-milling-assisted modification on lithium-extraction slag. This unexpectedly improves the secondary extraction of deeply embedded lithium from the slag, enabling excellent lithium extraction without the need for high-temperature treatments such as roasting. Furthermore, the physicochemical characteristics of the secondary lithium-extraction slag are further optimized, resulting in unexpectedly excellent performance in concrete recycling applications. For example, the wear resistance, flexural strength, and compressive strength of concrete produced from recycled secondary lithium-extraction slag can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the XRD pattern of lithium extraction slag;

[0037] Figure 2 This is the XRD pattern of the secondary lithium extraction slag in Example 1;

[0038] Figure 3 This is the XRD pattern of the lithium-enriched material in Example 1;

[0039] Figure 4 This is the XRD of the lithium carbonate prepared in Example 1. DETAILED DESCRIPTION

[0040] The following is a further description of the present invention with reference to the accompanying drawings and embodiments.

[0041] In the following cases, as an optional solution, lithium slag (XRD see Figure 1 ), mainly containing SiO220-35%, CaO 10-30%, Al2O3 5-30%, and about 0.35% lithium, and is produced from a lithium mine in Jiangxi. In the present invention, the above-mentioned about can be, for example, ±0.05%.

[0042] Example 1

[0043] 1. Crushing and screening: Use a crusher to crush the 10 mm block lithium extraction slag into 2 mm small pieces, and then use a disc crusher to crush the 2 mm small pieces into powder.

[0044] 2. Ball milling: Weigh 300 g of the above-mentioned lithium extraction slag, add 3 g of copper sulfate as a ball milling aid, with a ball-to-material ratio of 3:1, a rotation speed of 350 rpm, and a ball milling time of 5 min to obtain ball milled mixture A.

[0045] 3. Water immersion treatment: The ball milled mixture A was subjected to water immersion treatment with a liquid-to-solid ratio of 3:1 (ml / g). After stirring and washing for 1 h, it was filtered to obtain the secondary lithium extraction slag (see XRD). Figure 2 ) and lithium solution, the lithium dissolution rate is 98.3%.

[0046] 4. Lithium enrichment: The ferrophosphorus slag (mainly FePO4) after selective lithium extraction from waste lithium iron phosphate cathode materials was added to the filtrate to enrich lithium. The liquid-solid ratio was 10:1 (ml / g). The adsorption process temperature was 60-90 °C. The adsorption time was 2 h under alkaline conditions (pH was adjusted to 11-12 by adding sodium hydroxide). The adsorption rate was 93.61%. The XRD results of the enriched material were as follows: Figure 3 (Iron is an amorphous phase.) After enrichment, lithium is extracted using dilute hydrochloric acid (1 M concentration) at a liquid-to-solid ratio of 3:1 (ml / g) for 1 h. The pH at the leaching endpoint is controlled between 2 and 3 to obtain lithium-rich solution B and iron-containing filter residue.

[0047] 5. Lithium precipitation: add sodium carbonate as precipitant to lithium-rich solution B, adjust the pH to 9-10, filter to remove copper-containing residue, continue to add sodium carbonate to adjust the pH to 11-12, evaporate, crystallize, filter and wash to obtain lithium carbonate, the purity of which can reach 99.5%; XRD shows Figure 4 The final total lithium recovery rate was 86.3%.

[0048] 6. Lithium slag application: The concrete test size for abrasion and compressive strength is 10 cm × 10 cm × 10 cm, and the test size for flexural strength is 10 cm × 10 cm × 40 cm. The mix ratio of lithium slag concrete is calculated according to JGJ55-2011 "Standard for Design of Ordinary Concrete Mix Ratio". Lithium slag is used to replace cement. The ingredients are mixed evenly and allowed to stand for 24 hours before demolding. After demolding, the concrete is placed in a water tank for curing for 28 days before performance testing. For example, if the water is 160 kg / m 3 , cement 240 kg / m 3 , secondary lithium extraction slag 60 kg / m 3 , sand 750 kg / m 3 , crushed stone 1120 kg / m 3 The mixture was mixed to obtain a slurry, which was then cured to obtain 20% lithium slag-doped concrete. The test operation method was in accordance with the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The wear rate of the concrete doped with 20% lithium slag was measured to be 2.1 kg / m 2 The compressive strength of each cubic meter is 37.7 MPa and the flexural strength is 5.6 MPa.

[0049] Example 2

[0050] Compared with Example 1, the only difference is that the auxiliary agent is changed, specifically:

[0051] Group A: Copper chloride was used as the additive during ball milling, and all other conditions remained unchanged. The lithium dissolution rate in step 3 was 92.84%, and the concrete wear rate was 2.5 kg / m 2 , the compressive strength is 45.8 MPa and the flexural strength is 5.4 MPa.

[0052] Group B: Copper nitrate was used as the additive during ball milling, and all other conditions remained unchanged. The lithium dissolution rate in step 3 was 88.7%, and the concrete wear rate was 2.2 kg / m 2 , the compressive strength is 41.8 MPa and the flexural strength is 4.4 MPa.

[0053] Group C: The copper sulfate content during ball milling was 0.5% of the weight of the lithium slag. The lithium dissolution rate in step 3 was 86.85%, and the concrete wear rate was 5.1 kg / m 2 , the compressive strength is 31.4 MPa and the flexural strength is 4.1 MPa.

[0054] Group D: The copper sulfate content during ball milling was 3% of the weight of the lithium extraction slag. The lithium dissolution rate in step 3 was 81.44%, and the concrete wear was 2.8 kg / m 2 , the compressive strength is 39.8 MPa and the flexural strength is 5.9 MPa.

[0055] Group E: The ball milling speed was 500 rpm, and other conditions remained unchanged. The lithium dissolution rate in step 3 was 91.91%, and the concrete wear was 5.1 kg / m 2 , the compressive strength is 24.2 MPa and the flexural strength is 4.7 MPa.

[0056] Example 3

[0057] Compared with Example 1, the only difference is that the single factor conditions in Table 1 are changed. The operations and parameters are the same as those in Example 1. The results are shown in Table 1:

[0058]

[0059] Example 4

[0060] Compared with Example 1, the only difference is that the ratio of cement and secondary lithium extraction slag in concrete is changed (the total amount of cement and secondary lithium extraction slag is 300 kg / m 3 The secondary lithium extraction slag is 0, 30, and 60 kg / m 3 , the corresponding cement is 300, 270, 240 kg / m 3, the lithium slag doping ratio represented is 0, 10, 20%), and the wear loss measured by mechanical properties test is 6kg / m 2 , 4.1 kg / m 2 , 2.1 kg / m 2 The compressive strength of each cubic meter is 24.6 kg / m 2 , 29.9 kg / m 2 , 37.7 MPa, and the flexural strength per cubic meter is 4.1 kg / m 2 , 4.7 kg / m 2 , 5.6 MPa.

[0061] Example 5

[0062] Compared with Example 1, the only difference is that in step 4, dolomite or zeolite is added to the ball-milled leachate instead of ferrophosphorus slag for lithium enrichment, and the lithium adsorption rate is 91.47% and 83.9%. The lithium-rich slag after adsorption or chemical precipitation is leached with dilute hydrochloric acid (concentration of 1~2 M) at 50-80 ° C, the liquid-solid ratio is 10~40 mL / g, the reaction time is 1~3 h, and a precipitant is added to the lithium-rich solution. The final lithium recovery rate is 81.5%~84.82%.

[0063] Comparative Example 1

[0064] Compared with Example 1, the only difference is that no additives were added during ball milling. Other operations and parameters were the same as in Example 1. The results showed that the lithium dissolution rate in step 3 was 80.77%. The measured concrete wear was 5.5 kg / m 2 The compressive strength per cubic meter is 22.3 MPa, and the flexural strength per cubic meter is 3.9 MPa.

[0065] Comparative Example 2

[0066] Compared with Example 1, the only difference is that in step 2, equal amounts of the following components are used as auxiliary agents, and other operations and parameters are the same as those in Example 1.

[0067] Group A: Ferric chloride was used instead of copper sulfate as an additive;

[0068] Group B: Calcium chloride was used instead of copper sulfate as an additive;

[0069] The results are:

[0070] Group A: The lithium dissolution rate in step 3 was 82.31%, and the concrete wear was 4.5 kg / m 2 The compressive strength per cubic meter is 28.3 MPa, and the flexural strength per cubic meter is 5.4 MPa.

[0071] Group B: The lithium dissolution rate in step 3 was 77.31%, and the wear rate of concrete measured by mechanical properties test was 5.2kg / m 2 The compressive strength per cubic meter is 33.7 MPa, and the flexural strength per cubic meter is 3.9 MPa.

[0072] It can be seen that the extraction effect and the concrete performance of the secondary lithium extraction slag are not as good as those of the present invention.

[0073] Comparative Example 3

[0074] Compared with Example 1, the only difference is that the copper sulfate and lithium extraction slag were not pre-dry ball-milled. Instead, the copper sulfate was directly dissolved in water and then the lithium extraction slag was added (the amount of copper sulfate was the same as in Example 1, and the liquid-to-solid ratio of the copper sulfate solution to the lithium extraction slag was 3 ml / g). The process was pre-ball-milled for 5 minutes and then leached for 1 hour. The other operations and parameters were the same as in Example 1. The lithium dissolution rate in step 3 was 91.79%, and the wear loss of the concrete measured by the mechanical properties test was 7.2 kg / m 2 The compressive strength per cubic meter is 23.5 MPa, and the flexural strength per cubic meter is 2.1 MPa.

[0075] It can be seen that the extraction effect and concrete performance of pre-ball milling with additives and subsequent leaching are not as good as the improved lithium leaching and concrete application performance of the secondary lithium extraction slag of the solution of the present invention.

Claims

1. A secondary lithium extraction method for lithium slag, characterized in that: The lithium extraction slag and the copper-based additive are mixed and ball-milled, and then subjected to water immersion treatment and solid-liquid separation to obtain lithium liquid and secondary lithium extraction slag; The copper-based additive includes at least one of copper sulfate, copper chloride and copper nitrate.

2. The secondary lithium extraction method from lithium extraction slag according to claim 1, wherein: The lithium extraction slag is the leaching residue after lithium is extracted from lepidolite concentrate by sulfate roasting; Preferably, the lithium extraction slag includes at least one phase of phosphate aluminum silicate, leucite and sodalite; Preferably, the lithium extraction slag has a lithium content of 0.2-0.5 wt.%, a SiO2 content of 20-35 wt.%, a CaO content of 10-30 wt.%, an Al2O3 content of 8-10 wt.%, and a Fe2O3 content of 0.8-2.7 wt.%.

3. The secondary lithium extraction method from lithium extraction slag according to claim 1, wherein: The copper-based additive is 0.5-3% by weight of the lithium extraction slag, preferably 0.8-1.2%, and more preferably 0.9-1.1%.

4. The secondary lithium extraction method from lithium extraction slag according to claim 1, wherein: The ball mill speed is 200~500 rpm; Preferably, the ball milling time is 1 to 10 min.

5. The secondary lithium extraction method from lithium extraction slag according to claim 1, characterized in that: The liquid-to-solid ratio during the water immersion process is 2 to 10:1; Preferably, the temperature of the water immersion process is 10-40°C; Preferably, the immersion time is 0.5 to 5 h.

6. The secondary lithium extraction method for lithium extraction slag according to any one of claims 1 to 5, characterized in that: The lithium solution is directly subjected to lithium precipitation treatment, or the lithium salt is concentrated and then subjected to lithium precipitation treatment to obtain a lithium product.

7. A method for secondary lithium extraction and resource utilization of lithium extraction slag, characterized in that: The lithium extraction slag is treated by the secondary lithium extraction method according to any one of claims 1 to 6 to obtain secondary lithium extraction slag; and the secondary lithium extraction slag is used as an additive to prepare concrete slurry and / or concrete.

8. The method for secondary lithium extraction and resource utilization of lithium extraction slag for preparing concrete according to claim 7, characterized in that: The secondary lithium extraction slag, cement and aggregate are slurried with water to prepare concrete slurry.

9. The method for secondary lithium extraction and resource utilization of lithium extraction slag for preparing concrete according to claim 8, characterized in that: In concrete slurry, water is 100~200 kg / m 3 , cement dosage is 200~300 kg / m 3 The amount of secondary lithium extraction slag is 20~100 kg / m 3 The amount of aggregate is 1500~2000 kg / m 3 .

10. The method for secondary lithium extraction and resource utilization of lithium extraction slag for preparing concrete according to claim 8 or 9, characterized in that: The concrete slurry is cured to obtain concrete.

Images