Process and method for recovering lithium from waste medical lithium carbonate

Abstract

The invention discloses a process and a method for recovering lithium from waste medical lithium carbonate, and relates to the technical field of waste medical lithium carbonate recovery, and the process comprises the following steps: S1, carrying out ball milling on a waste medical lithium carbonate material to be recovered through a ball milling process, and then roasting through a roasting process; s2, carrying out ball milling on the roasted lithium material through a ball milling process; s3, performing a water soaking process on the ball-milled lithium material to remove some water-soluble impurities, and performing suction filtration to leave filter residues; the technical scheme is specially used for recycling the waste medical lithium carbonate, the scheme is higher in pertinence, battery-grade lithium carbonate can be recycled, the blank of the current process is effectively made up, the problem of roasting caking in the traditional process is solved, the remarkable effect of acid dissolution defoaming can be achieved, and the method is suitable for industrial production. And the impurity removal step is optimized according to the characteristics of the impurities in the medical lithium carbonate, so that the impurity removal efficiency and effect are remarkably improved, meanwhile, the problems of low lithium recovery rate and high impurity content are solved, and the high recovery rate of the battery-grade lithium carbonate is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of recycling waste medical lithium carbonate, and in particular to a process and method for recycling lithium from waste medical lithium carbonate. Background Art

[0002] Based on the rapid development of new energy electric vehicles and lithium-ion smart device industries in recent years, the global demand for lithium resources has exploded. As an indispensable raw material for lithium-ion batteries, the demand for lithium carbonate has also continued to rise. With the consumption of lithium ore, high-grade lithium ore is becoming increasingly scarce. At the same time, the price of raw ore continues to rise. How to purify lithium carbonate from waste lithium carbonate products has also become a problem that the current large-scale lithium carbonate industry needs to consider. Medical lithium carbonate tablets are symptomatic drugs for the treatment of bipolar disorder composed of lithium carbonate and excipients. Lithium carbonate is an active ingredient that has the function of preventing and treating bipolar disorder. However, due to the failure of many lithium carbonate tablets to be used in time, expiration and waste are very serious, which not only has a great impact on the environment, but also causes waste of resources.

[0003] According to a method for recovering lithium from waste lithium carbonate batteries with announcement number CN117285053A, the method comprises the following steps: 1. adding battery black powder into acid solution, and removing phosphorus iron slag through high temperature stirring and filtering; 2. adding activated carbon to remove grease, fluorine, phosphorus, copper and magnesium; 3. adding ammonia water into the filtrate for neutralization reaction, adjusting the pH value to 6-7, and performing ion exchange in a chelating resin after neutralization to obtain a lithium-containing solution; 4. performing MVR concentration on the lithium-containing solution until the mass concentration of lithium ions in the lithium solution reaches 22-24 g / L; 5. adding sodium carbonate solution into the lithium-containing solution to obtain an ammonium salt solution and a lithium carbonate precipitate. precipitate; 6. Concentrate and crystallize the ammonium salt solution to obtain industrial-grade ammonium sulfate, and centrifuge and dry the lithium carbonate to obtain industrial-grade lithium carbonate; 7. Add alkali salt and sulfuric acid to the ammonium salt solution in step 5 for neutralization reaction to obtain a decarbonized ammonium salt solution; 8. Perform MVR concentration on the decarbonized ammonium salt solution, and produce sodium sulfate as a byproduct during the concentration process; 9. Evaporate the ammonium salt solution after MVR concentration to precipitate lithium carbonate, evaporate until sodium sulfate is close to saturation, and then cool the solution to below 10°C until 95% sodium sulfate crystals are precipitated, and then evaporate to precipitate lithium carbonate. When the CO in the solution reaches the set temperature, repeat steps 6 and 7. The stirring temperature in step 1 is 85-100°C, and the stirring time is 2-3h. The acid solution is a dilute sulfuric acid with a sulfuric acid content of 6wt% to 9wt% and a hydrogen peroxide content of 0.25wt% to 1wt%, which is prepared from a semiconductor pickling sulfuric acid waste liquid with a sulfuric acid content of 55wt% to 65wt% and a hydrogen peroxide content of 2wt% to 6wt%. The chelating resin in step 3 is a weak acid cation exchange resin. The weak acid cation exchange resin is a polystyrene iminodiacetic acid resin. The drying temperature of the lithium carbonate precipitate in step 6 is 110-120° C., and the drying time is 3.5-4.5 hours.

[0004] Regarding the above-mentioned related schemes, the above are technologies for the recycling of lithium ore and lithium batteries, and there is no technical solution for the recycling of waste medical lithium carbonate. When the technology for recycling lithium ore is used to recycle waste medical lithium carbonate, the following problems exist: when roasting waste medical lithium carbonate, a large number of hard blocks are easily generated, which not only affects the roasting efficiency, but also reduces the lithium recovery rate; in the acid dissolution stage, a large number of bubbles are generated when the waste medical lithium carbonate reacts with acid, which not only interferes with the dissolution process, but also affects the smooth progress of subsequent processes; currently, the impurity removal process of lithium ore or lithium battery is applied, and the impurity content in waste medical lithium carbonate is still relatively high, which does not meet the requirements of battery-grade lithium carbonate, affecting its subsequent application value; in addition, the lithium recovery rate is relatively low, which wastes resources and increases the recovery cost. Summary of the invention

[0005] The object of the present invention is to provide a process and method for recovering lithium from waste medical lithium carbonate to solve the technical problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a method for recovering lithium from waste medical lithium carbonate, comprising the following steps:

[0007] S1. The waste medical lithium carbonate material to be recycled is firstly ball-milled by a ball-milling process, and then roasted by a roasting process;

[0008] S2, the calcined lithium material is ball milled again by ball milling process;

[0009] S3, the lithium material after ball milling is soaked in water to remove some water-soluble impurities, and then filtered to retain the residue;

[0010] S4, dissolving the filter residue in the above process by acid dissolution process, and filtering and retaining filtrate 1;

[0011] S5, adding sodium hydroxide solution to the filtrate 1, and performing precipitation reaction to remove iron, zinc and magnesium, and filtering and retaining the filtrate 2;

[0012] S6, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2, and performing precipitation reaction to remove calcium, and filtering to obtain a lithium-containing solution;

[0013] S7. Add the lithium-containing solution into a sodium carbonate solution to obtain a lithium carbonate precipitate and a sulfate solution.

[0014] Preferably, the calcination process conditions in S1 are 500-600° C. and 1 h of calcination time; and the ball milling process conditions are 400 r / min and 1 h of ball milling time.

[0015] Preferably, the ball milling process conditions in S2 are 400 r / min and the ball milling time is 1 h-3 h.

[0016] Preferably, the water soaking process condition in S3 is 50° C., and the stirring soaking time is 2 h-6 h.

[0017] Preferably, the acid dissolution process conditions in S4 are 50° C., 98% concentrated sulfuric acid is added to adjust the pH to 2.5, and the stirring reaction time is 1 hour.

[0018] Preferably, the precipitation reaction conditions in S5 are 60° C., the pH is adjusted to 8.5, and the stirring reaction time is 1 hour. This operation process is a one-time impurity removal.

[0019] Preferably, the chemical reaction equations involved in S5 are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4.

[0020] Preferably, the precipitation reaction conditions in S6 are 60° C., the pH is adjusted to 12, and the amount of sodium carbonate used is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH.

[0021] Preferably, in S7, lithium solution is added dropwise to the sodium carbonate solution, the reaction temperature is 95° C., and the reaction is continued for 1 hour after the lithium solution is added dropwise.

[0022] Preferably, the chemical reaction equation involved in S7 is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention is a technical solution specifically used to recycle waste pharmaceutical lithium carbonate. The solution is more targeted and can successfully recycle battery-grade lithium carbonate, effectively filling the gap in the current process. This technology can not only solve the roasting agglomeration problem existing in the traditional process, but also achieve the significant effect of acid dissolution and defoaming, and by optimizing the impurity removal steps, it significantly improves the removal efficiency and effect of impurities, while overcoming the problem of low lithium recovery rate and ensuring a high recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The present invention is a process flow chart of the recovery of pharmaceutical lithium carbonate. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Embodiment 1

[0028] See also Figure 1 The present invention provides a technical solution: a method for recovering lithium from waste medical lithium carbonate, comprising the following steps:

[0029] S1. The waste medical lithium carbonate material to be recycled is first ball-milled by a ball-milling process, and then roasted by a roasting process. Specifically, in this step, the ball-milling process conditions are 400r / min, and the ball-milling time is 1h; the roasting process conditions are 500°C, and the roasting time is 1h.

[0030] S2, the calcined lithium material is subjected to a water soaking process to remove some water-soluble impurities, and the filter residue is filtered out. Specifically, in this step, the water soaking process condition is 50° C. and stirred for 2 hours;

[0031] S3, dissolving the filter residue of the above process by acid dissolution process, filtering and retaining filtrate 1, specifically, in this step, the acid dissolution process conditions are 50 ° C, adding 98% concentrated sulfuric acid to adjust the pH to 2.5, and the stirring reaction time is 1h;

[0032] S4, adding sodium hydroxide solution to the filtrate 1, and performing precipitation reaction to remove iron, zinc and magnesium, and filtering to retain the filtrate 2. Specifically, in this step, the precipitation reaction condition is 60°C, the pH is adjusted to 8.5, and the stirring reaction time is 1h. This operation process is a one-time impurity removal, and the chemical reaction equations involved in this step are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4;

[0033] S5, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2, and performing precipitation reaction to remove calcium, and filtering to obtain a lithium-containing solution. The precipitation reaction condition is 60° C., and the pH is adjusted to 12. The amount of sodium carbonate is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved in this step is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH;

[0034] S6. Add the lithium-containing solution to the sodium carbonate solution at a reaction temperature of 95°C. After the lithium solution is added, react for another hour to obtain lithium carbonate precipitate and sulfate solution. The chemical reaction equation involved in this step is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

[0035] Embodiment 2

[0036] The present invention provides a technical solution: a method for recovering lithium from waste medical lithium carbonate, comprising the following steps:

[0037] S1. The waste medical lithium carbonate material to be recycled is first ball-milled and then calcined. Specifically, in this step, the ball-milling process is 400 r / min, the ball-milling time is 1 h, and the calcination process is 600 ° C, and the calcination time is 1 h;

[0038] S2, the calcined lithium material is subjected to a water soaking process to remove some water-soluble impurities, and the filter residue is filtered out. Specifically, in this step, the water soaking process condition is 50° C., and the stirring soaking time is 2 h;

[0039] S3, dissolving the filter residue of the above process by acid dissolution process, filtering and retaining filtrate 1, specifically, in this step, the acid dissolution process conditions are 50 ° C, adding 98% concentrated sulfuric acid to adjust the pH to 2.5, and the stirring reaction time is 1h;

[0040] S4, adding sodium hydroxide solution to the filtrate 1 for precipitation reaction, removing iron, zinc and magnesium, and filtering to retain the filtrate 2. Specifically, in this step, the precipitation reaction condition is 60°C, the pH is adjusted to 8.5, and the stirring reaction time is 1h. This operation process is a one-time impurity removal, and the chemical reaction equations involved in this step are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4;

[0041] S5, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2 for precipitation reaction, removing calcium, and filtering to obtain a lithium-containing solution; the precipitation reaction condition is 60° C., the pH is adjusted to 12, and the amount of sodium carbonate is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved in this step is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH;

[0042] S6. Add the lithium-containing solution to the sodium carbonate solution at a reaction temperature of 95°C. After the lithium solution is added, react for another hour to obtain lithium carbonate precipitate and sulfate solution. The chemical reaction equation involved in this step is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

[0043] Embodiment 3

[0044] The present invention provides a technical solution: a method for recovering lithium from waste medical lithium carbonate, comprising the following steps:

[0045] S1. The waste medical lithium carbonate material to be recycled is first ball-milled by a ball milling process and then roasted by a roasting process. Specifically, in this step, the ball milling process condition is 400r / min, and the ball milling time is 1h; the roasting process condition is 600°C, and the roasting time is 1h;

[0046] S2, the calcined lithium material is subjected to a water soaking process to remove some water-soluble impurities, and the filter residue is filtered out. Specifically, in this step, the water soaking process condition is 50° C., and the stirring soaking time is 6 hours;

[0047] S3, dissolving the filter residue of the above process by acid dissolution process, filtering and retaining filtrate 1, specifically, in this step, the acid dissolution process conditions are 50 ° C, adding 98% concentrated sulfuric acid to adjust the pH to 2.5, and the stirring reaction time is 1h;

[0048] S4, adding sodium hydroxide solution to the filtrate 1 for precipitation reaction, removing iron, zinc and magnesium, and filtering to retain the filtrate 2. Specifically, in this step, the precipitation reaction condition is 60°C, the pH is adjusted to 8.5, and the stirring reaction time is 1h. This operation process is a one-time impurity removal, and the chemical reaction equations involved in this step are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4;

[0049] S5, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2 for precipitation reaction, removing calcium, and filtering to obtain a lithium-containing solution. The precipitation reaction condition is 60° C., and the pH is adjusted to 12. The amount of sodium carbonate is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved in this step is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH;

[0050] S6. Add the lithium-containing solution to the sodium carbonate solution at a reaction temperature of 95°C. After the lithium solution is added, react for another hour to obtain lithium carbonate precipitate and sulfate solution. The chemical reaction equation involved in this step is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

[0051] Embodiment 4

[0052] See also Figure 1 The present invention provides a technical solution: a method for recovering lithium from waste medical lithium carbonate, comprising the following steps:

[0053] S1. The waste medical lithium carbonate material to be recycled is first ball-milled by a ball milling process and then roasted by a roasting process. Specifically, in this step, the ball milling process condition is 400r / min, and the ball milling time is 1h; the roasting process condition is 600°C, and the roasting time is 1h;

[0054] S2, the calcined lithium material is then ball milled. Specifically, in this step, the ball milling process condition is 400r / min, and the ball milling time is 1h;

[0055] S3, the lithium material after ball milling is soaked in water to remove some water-soluble impurities, and the residue is filtered out. Specifically, in this step, the water soaking process condition is 50° C., and the stirring soaking time is 2 h;

[0056] S4, dissolving the filter residue of the above process by acid dissolution process, filtering and retaining filtrate 1, specifically, in this step, the acid dissolution process conditions are 50 ° C, adding 98% concentrated sulfuric acid to adjust the pH to 2.5, and the stirring reaction time is 1h;

[0057] S5. Add sodium hydroxide solution to the filtrate 1 for precipitation reaction to remove iron, zinc and magnesium, and filter and retain the filtrate 2. Specifically, in this step, the precipitation reaction condition is 60°C, the pH is adjusted to 8.5, and the stirring reaction time is 1h. This operation process is a one-time impurity removal, and the chemical reaction equations involved in this step are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4;

[0058] S6, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2 for precipitation reaction, removing calcium, and filtering to obtain a lithium-containing solution. The precipitation reaction conditions are 60° C., and the pH is adjusted to 12. The amount of sodium carbonate is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved in this step is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH;

[0059] S7. Add the lithium-containing solution into the sodium carbonate solution at a reaction temperature of 95°C. After the lithium solution is added, react for another hour to obtain lithium carbonate precipitate and sulfate solution. The chemical reaction equation involved in this step is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

[0060] Embodiment 5

[0061] See also Figure 1 The present invention provides a technical solution: a method for recovering lithium from waste medical lithium carbonate, comprising the following steps:

[0062] S1. The waste medical lithium carbonate material to be recycled is first ball-milled by a ball milling process and then roasted by a roasting process. Specifically, in this step, the ball milling process condition is 400r / min, and the ball milling time is 1h; the roasting process condition is 600°C, and the roasting time is 1h;

[0063] S2, the calcined lithium material is then ball milled. Specifically, in this step, the ball milling process condition is 400r / min, and the ball milling time is 3h;

[0064] S3, the lithium material after ball milling is soaked in water to remove some water-soluble impurities, and the residue is filtered out. Specifically, in this step, the water soaking process condition is 50° C., and the stirring soaking time is 2 h;

[0065] S4, dissolving the filter residue of the above process by acid dissolution process, filtering and retaining filtrate 1, specifically, in this step, the acid dissolution process conditions are 50 ° C, adding 98% concentrated sulfuric acid to adjust the pH to 2.5, and the stirring reaction time is 1h;

[0066] S5. Add sodium hydroxide solution to the filtrate 1 for precipitation reaction to remove iron, zinc and magnesium, and filter and retain the filtrate 2. Specifically, in this step, the precipitation reaction condition is 60°C, the pH is adjusted to 8.5, and the stirring reaction time is 1h. This operation process is a one-time impurity removal, and the chemical reaction equations involved in this step are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4;

[0067] S6, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2 for precipitation reaction, removing calcium, and filtering to obtain a lithium-containing solution. The precipitation reaction conditions are 60° C., and the pH is adjusted to 12. The amount of sodium carbonate is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved in this step is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH;

[0068] S7. Add the lithium-containing solution into the sodium carbonate solution at a reaction temperature of 95°C. After the lithium solution is added, react for another hour to obtain lithium carbonate precipitate and sulfate solution. The chemical reaction equation involved in this step is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

[0069] Working principle: the waste medical lithium carbonate material to be recycled is first ball-milled by a ball milling process, and then roasted by a roasting process. The roasted lithium material is ball-milled again by a ball milling process. The milled lithium material is soaked in water to remove some water-soluble impurities, filtered and retained by filter residue, the filter residue of the above process is dissolved by acid dissolution, filtered and retained by filtrate 1, sodium hydroxide solution is added to filtrate 1, and a precipitation reaction is carried out to remove iron, zinc and magnesium, filtered and retained by filtrate 2, sodium hydroxide solution, activated carbon and sodium carbonate solution are added to filtrate 2, and a precipitation reaction is carried out to remove calcium, filtered to obtain a lithium-containing solution, and the above lithium-containing solution is added to a sodium carbonate solution to obtain a lithium carbonate precipitate and a sulfate solution. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

[0070] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for recovering lithium from waste medical lithium carbonate, characterized in that: The steps include: S1. The waste medical lithium carbonate material to be recycled is firstly ball-milled by a ball-milling process, and then roasted by a roasting process; S2, the calcined lithium material is ball milled again by ball milling process; S3, the lithium material after ball milling is soaked in water to remove some water-soluble impurities, and then filtered to retain the residue; S4, dissolving the filter residue in the above process by acid dissolution process, and filtering and retaining filtrate 1; S5, adding sodium hydroxide solution to the filtrate 1, and performing precipitation reaction to remove iron, zinc and magnesium, and filtering and retaining the filtrate 2; S6, adding sodium hydroxide solution, activated carbon and sodium carbonate solution to the filtrate 2, and performing precipitation reaction to remove calcium, and filtering to obtain a lithium-containing solution; S7. Add the lithium-containing solution into a sodium carbonate solution to obtain a lithium carbonate precipitate and a sulfate solution.

2. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: The calcination process conditions in S1 are 500-600° C. and 1 h. The ball milling process conditions are 400 r / min and 1 h-3 h.

3. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: The ball milling process conditions in S2 are 400r / min and the ball milling time is 1h-3h.

4. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: The water soaking process condition in S3 is 50° C., and the stirring soaking time is 2 h to 6 h.

5. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: The acid dissolution process conditions in S4 are 50° C., 98% concentrated sulfuric acid is added to adjust the pH to 2.5, and the stirring reaction time is 1 hour.

6. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: The precipitation reaction conditions in S5 are 60° C., the pH is adjusted to 8.5, and the stirring reaction time is 1 hour. This operation process is a one-time impurity removal.

7. A method for recovering lithium from waste medical lithium carbonate according to claim 6, characterized in that: The chemical reaction equations involved in S5 are: ZnSO4+2NaOH=Zn(OH)2↓+Na2SO4, MgSO4+2NaOH=Mg(OH)2↓+Na2SO4; Fe2(SO4)3+6NaOH=2Fe(OH)3↓+3Na2SO4.

8. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: The precipitation reaction conditions in S6 are 60°C, the pH is adjusted to 12, and the amount of sodium carbonate used is determined according to the calcium content in the filtrate 2. This operation process is a secondary impurity removal, and the chemical reaction equation involved is: Ca(OH)2+Na2CO3=CaCO3↓+2NaOH.

9. A method for recovering lithium from waste medical lithium carbonate according to claim 1, characterized in that: In the step S7, lithium solution is added dropwise to the sodium carbonate solution, the reaction temperature is 95° C., and the reaction is continued for 1 hour after the lithium solution is added dropwise.

10. A method for recovering lithium from waste medical lithium carbonate according to claim 9, characterized in that: The chemical reaction equation involved in S7 is: Li2SO4+Na2CO3=Li2CO3↓+Na2SO4.

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