Method for extracting lithium sulfate from waste residues

Abstract

The invention relates to a method for extracting lithium sulfate from waste residues, and belongs to the technical field of lithium sulfate extraction, and the method comprises the following steps: S1, slurrying primary purified residues: putting the primary purified residues into a reaction kettle according to a ratio of the purified residues to water of 1: 3, then adding condensed water at 90 DEG C, and fully stirring for more than 30 minutes to complete primary slurrying; adjusting the pH value: adding sulfuric acid into the reaction kettle after the primary slurrying until the pH value in the reaction kettle is stabilized at 3-5; filter pressing: carrying out filter pressing to obtain a primary lithium sulfate solution and primary leaching residues; s2, slurrying the secondary purified slag: putting the primary leached slag obtained in the previous step into the reaction kettle according to the ratio of the purified slag to water of 1: 3, and stirring to complete secondary slurrying; adjusting the pH value: adding sulfuric acid into the reaction kettle after the secondary slurrying until the pH value in the reaction kettle is stabilized between 6 and 7; and filter pressing: carrying out filter pressing to obtain a secondary lithium sulfate solution and secondary leaching residues.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium sulfate extraction, in particular to a method for extracting lithium sulfate from waste residue. BACKGROUND

[0002] In the prior art, in the process of producing lithium carbonate with lithium sulfate solution as raw material, a process step of primary purification and secondary purification is required to remove fluorine and impurities such as calcium, magnesium, iron and aluminum. After the primary purification of lithium sulfate solution to remove fluorine, solid waste residue is generated as primary purification residue. After the lithium sulfate solution after pressure filtration enters the secondary purification to remove calcium, magnesium, iron and aluminum, solid waste residue is generated as secondary purification residue. A large amount of purification residue is generated after two purifications. According to statistics, about 500 kg of purification residue is generated for every ton of lithium carbonate produced.

[0003] The above-mentioned purification residue still contains a certain amount of valuable lithium after water washing. Selling such purification residue is very cheap, which also causes the loss of lithium metal. The traditional treatment method is to mix the purification residue with lithium concentrate and then perform roasting treatment. Since the water content of the purification residue is about 35%, the water needs to be dried before roasting, and then various sulfates are added for treatment. The treatment cost of the purification residue is high, and the treatment cost required from drying and sulfate treatment to lithium sulfate purification liquid generation is more than 900 yuan per ton of purification residue. Moreover, a long process flow is required to change the purification residue into lithium sulfate purification liquid, and the lithium recovery rate during this period is only between 75-80%. In addition, harmful gases such as sulfur dioxide and hydrogen fluoride are easily generated during the roasting process, which increases the cost of environmental protection treatment.

[0004] Chinese patent application No. 202210337594.X discloses a comprehensive recovery method for lithium-containing purification residue, which includes the following steps: 1. adding lithium-containing purification residue and industrial water into a ball mill; 2. obtaining lithium-containing purification residue slurry after ball milling, and then entering a pit with stirring; 3. adding industrial-grade concentrated sulfuric acid to the lithium-containing purification residue slurry until the pH value is stable at 5-6, and then reacting for 2 hours; 4. leaching the reacted lithium-containing purification residue slurry to obtain lithium sulfate solution and leaching residue, and recovering the lithium metal component therein; uniformly treating each purification residue by using a ball mill to grind the residue, which requires a purchase cost and consumes electric energy during operation; using a ratio of purification residue to industrial water of 1:1, using industrial-grade concentrated sulfuric acid to adjust the pH value to 5-6, and stirring for 2 hours to maximize the extraction rate. The whole process from step 1 to step 4 takes a long time, the recovery cost is high, and the recovery efficiency is low. SUMMARY

[0005] In order to overcome the above-mentioned defects of the prior art, the present application provides a method for extracting lithium sulfate from waste residue, so as to overcome the shortcomings of the prior art, effectively extract lithium in the waste residue in a low-cost and fast way, and maximize the extraction rate and recovery efficiency of lithium.

[0006] In order to achieve the above-mentioned purposes of the present application, the present application provides a method for extracting lithium sulfate from waste residue, the method comprising the following steps: S1: primary purification residue The primary purification residue comprises the following steps: Slurry: the primary purification residue is put into a reaction kettle according to a ratio of 1:3 of the purification residue to water, then 90 DEG C condensed water is added, and fully stirred for more than 30 minutes to complete the first slurry; PH value adjustment: sulfuric acid is added to the reaction kettle after the above-mentioned first slurry to stabilize the PH value in the reaction kettle to 3-5, the temperature is kept at 60-80 DEG C, and fully stirred and reacted for 30-60 minutes; Filter pressing: the slurry after the reaction in the above step is transported to a filter press for filter pressing to obtain a primary lithium sulfate solution and a primary leaching residue; S2: secondary purification residue The secondary purification residue comprises the following steps: Slurry: the primary leaching residue in the above step is put into a reaction kettle according to a ratio of 1:3 of the purification residue to water, then 90 DEG C condensed water is added, and fully stirred for more than 30 minutes to complete the second slurry; PH value adjustment: sulfuric acid is added to the reaction kettle after the above-mentioned second slurry to stabilize the PH value in the reaction kettle to 6-7, the temperature is kept at 60-80 DEG C, and fully stirred and reacted for 30-60 minutes; Filter pressing: the slurry after the reaction in the above step is transported to a filter press for filter pressing to obtain a secondary lithium sulfate solution and a secondary leaching residue.

[0007] Further, in the step S1, the primary lithium sulfate solution obtained after filter pressing is transported to a primary purification reaction kettle for defluorination.

[0008] Further, in the step S2, the secondary lithium sulfate solution obtained after filter pressing is transported to a secondary purification reaction kettle for removal of calcium, magnesium, iron and aluminum impurities.

[0009] Further, in the step S1, the reaction temperature during the PH value adjustment is 70 DEG C.

[0010] Further, in the step S2, the reaction temperature during the PH value adjustment is 70 DEG C.

[0011] Further, in the step S1, the fully stirred and reacted time during the PH value adjustment is 40 minutes.

[0012] Further, in the step S2, the sufficient stirring during the adjustment of the PH value and the reaction for 50 minutes.

[0013] Compared with the prior art, the present application has the following advantages: The method for extracting lithium sulfate from the waste residue after purification of lithium sulfate in the present application has the following advantages: the recovery rate of lithium in the primary purification residue is more than 90% after the primary purification residue is treated, the recovery rate of lithium in the secondary purification residue is more than 99% after the secondary purification residue is treated, 90 DEG C condensed water is used to realize the value of wastewater reuse, meet the temperature required by the reaction (60 DEG C-80 DEG C) and save the heat consumption, the primary purification residue and the secondary purification residue are treated respectively and the PH value is adjusted in different ranges, and the maximum extraction rate of lithium in the purification residue is realized.

[0014] The present application has the following advantages: the process steps are less, the process route is short, the process equipment investment is small, the production cost of recovery is extremely low, the comprehensive cost is about 90 yuan per ton of purification residue treated, the process procedure is simple, the operation is easy, the benefit is remarkable, the production raw material of recovered lithium is the byproduct sulfuric acid and condensed water in the process of lithium carbonate, the recovery cost is greatly reduced, the process steps are less, the process route is short, the production cycle is short, and the production efficiency of recovery is greatly improved. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The flow chart of the embodiment of the present application is shown. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the embodiment of the present application clearer, the technical scheme in the embodiment of the present application will be described clearly and completely in combination with the drawings of the present application. Obviously, the described embodiment is a part of the embodiments of the present application, not all the embodiments. The embodiment of the present application will be described in combination with the drawings.

[0017] REFERENCE Figure 1 A method for extracting lithium sulfate from waste residue, comprising the following steps: S1: primary purification residue The primary purification residue comprises the following steps: Slurry: according to the ratio of 1:3 of the purification residue to water, the primary purification residue is put into a reaction kettle, then 90 DEG C condensed water is added, and the primary slurry is completed after sufficient stirring for more than 30 minutes; PH value adjustment: sulfuric acid is added to the reaction kettle after the above primary slurry to stabilize the PH value in the reaction kettle to 3-5, the temperature is kept at 60 DEG C-80 DEG C, and the reaction is carried out after sufficient stirring for 30-60 minutes; In other embodiments of the present embodiment, when adjusting the pH value, sulfuric acid is added to the reactor after the first slurry is formed until the pH value in the reactor is stabilized at 3 or 5, the temperature is maintained at 60°C or 80°C, and the mixture is fully stirred and reacted for 30 minutes or 60 minutes. Filter pressing: the slurry after the reaction is completed is transported to a filter press for filter pressing to obtain a first lithium sulfate solution and a first leaching residue; The first lithium sulfate solution obtained after the first leaching residue is treated as described above is transported to the reactor of the first purification process to remove fluorine to meet the fluorine content standard of the lithium sulfate solution entering the next process. S2: second purification residue The second purification residue includes the following steps: Slurry formation: the first leaching residue of the above step is put into the reactor according to a ratio of 1:3 of the purification residue to water, then condensed water at 90°C is added, the mixture is fully stirred for 30 minutes, and the second slurry formation is completed. PH value adjustment: sulfuric acid is added to the reactor after the second slurry formation until the pH value in the reactor is stabilized between 6 and 7, the temperature is maintained between 60°C and 80°C, and the mixture is fully stirred and reacted for 30-60 minutes. In other embodiments of the present embodiment, when adjusting the pH value, sulfuric acid is added to the reactor after the second slurry formation until the pH value in the reactor is stabilized at 6 or 7, the temperature is maintained at 60°C or 80°C, and the mixture is fully stirred and reacted for 30 minutes or 60 minutes. Filter pressing: the slurry after the reaction is completed is transported to a filter press for filter pressing to obtain a first lithium sulfate solution and a first leaching residue;

[0018] The second lithium sulfate solution obtained after the treatment is transported to the reactor of the second purification process to remove impurities such as calcium, magnesium, iron, and aluminum to meet the calcium, magnesium, iron, and aluminum impurity content standard of the lithium sulfate solution entering the next process.

[0019] In some embodiments, in step S1, the first lithium sulfate solution obtained after filter pressing is transported to the first purification reactor through a pipeline for fluorine removal to meet the fluorine content standard of the lithium sulfate solution entering the next process.

[0020] In some embodiments, in step S2, the second lithium sulfate solution obtained after filter pressing is transported to the second purification reactor through a pipeline for removal of calcium, magnesium, iron, and aluminum impurities to meet the calcium, magnesium, iron, and aluminum impurity content standard of the lithium sulfate solution entering the next process.

[0021] In some embodiments, in step S1, the reaction temperature when adjusting the pH value is 70°C to provide a suitable temperature for sufficient reaction.

[0022] In some embodiments, in step S2, the reaction temperature when adjusting the pH value is 70 DEG C, so as to provide a suitable temperature for sufficient reaction.

[0023] In some embodiments, in step S1, sufficient stirring is performed when adjusting the pH value, and the reaction is performed for 40 minutes, so as to perform sufficient reaction.

[0024] In some embodiments, in step S2, sufficient stirring is performed when adjusting the pH value, and the reaction is performed for 50 minutes, so as to perform sufficient reaction.

[0025] The method for extracting lithium sulfate from the waste residue after purification of lithium sulfate according to the present application has the following advantages: after the primary purification residue is treated, the recovery rate of lithium in the primary purification residue is above 90%; after the secondary purification residue is treated, the recovery rate of lithium in the secondary purification residue is above 99%; 90 DEG C condensate water is used, which realizes the value of waste water reuse, meets the temperature 60 DEG C-80 DEG C required by the reaction, and saves the consumption of heat energy; the primary purification residue and the secondary purification residue are treated respectively, and the stable adjustment of different pH value ranges is performed, so that the maximum extraction rate of lithium in the purification residue is realized.

[0026] The present application has the following advantages: the process steps are few, the process route is short, the investment of process equipment is small, the production cost of recovery is extremely low, the comprehensive cost is about 90 yuan per ton of purification residue treated, the process procedure is simple, the operation is easy, the benefit is remarkable; the production raw material of recovered lithium is the by-product sulfuric acid and condensate water in the process of lithium carbonate, which greatly reduces the recovery cost; the process steps are few, the process route is short, the production cycle is short, and the production efficiency of recovery is greatly improved.

[0027] The technical solutions of the present application are described above in combination with specific embodiments, but it should be noted that the above description is only for explaining the solutions of the present application, and cannot be explained as the specific limitation of the protection scope of the present application in any way. Based on the explanation herein, other specific embodiments or equivalent substitutions of the present application can be thought of by those skilled in the art without any creative labor, which will fall into the protection scope of the present application.

Claims

1. A method for extracting lithium sulfate from waste residue, characterized in that: The method comprises the following steps: S1: primary purification slag The primary slag purification comprises the following steps: Slurrying: put the first purification residue into the reactor at a ratio of 1:3 purification residue to water, then add 90℃ condensed water, stir thoroughly for more than 30 minutes to complete the first slurrying; Adjusting the pH value: adding sulfuric acid to the reactor after the primary pulping until the pH value in the reactor stabilizes at 3-5, maintaining the temperature between 60°C and 80°C, stirring thoroughly and reacting for 30-60 minutes; Filter pressing: The slurry after the previous reaction is transported to a filter press for filter pressing to obtain a primary lithium sulfate solution and a primary leaching residue; S2: Secondary purification slag The secondary purification slag comprises the following steps: Pulping: put the primary leaching residue from the above step into the reactor at a ratio of 1:3 purified residue to water, then add 90°C condensed water and stir thoroughly for 30 minutes to complete the secondary slurrying; Adjust the pH value: add sulfuric acid into the reactor after the secondary pulping until the pH value in the reactor is stable between 6-7, maintain the temperature between 60℃-80℃, stir well and react for 30-60 minutes; Filter pressing: The slurry after the above reaction is transported to a filter press for filter pressing to obtain a secondary lithium sulfate solution and secondary leaching residue.

2. The method for extracting lithium sulfate from waste residue according to claim 1, wherein In the step S1, the primary lithium sulfate solution obtained after pressure filtration is transported to a primary purification reactor through a pipeline for defluorination.

3. The method for extracting lithium sulfate from waste residue according to claim 1, wherein In step S2, the secondary lithium sulfate solution obtained after pressure filtration is transported to a secondary purification reactor through a pipeline to remove calcium, magnesium, iron, and aluminum impurities.

4. The method for extracting lithium sulfate from waste residue according to claim 1, wherein In step S1, the reaction temperature when adjusting the pH value is 70°C.

5. The method for extracting lithium sulfate from waste residue according to claim 1, wherein In step S2, the reaction temperature when adjusting the pH value is 70°C.

6. The method for extracting lithium sulfate from waste residue according to claim 1, wherein In the step S1, the pH value is adjusted by sufficient stirring and the reaction is carried out for 40 minutes.

7. The method for extracting lithium sulfate from waste residue according to claim 1, wherein: In step S2, the pH value is adjusted by sufficient stirring and the reaction is carried out for 50 minutes.

Images