Method for preparing battery-grade lithium carbonate from nanocrystallization lithium-rich liquid

Abstract

The invention discloses a method for preparing battery-grade lithium carbonate from a nanocrystallization lithium-rich liquid, which adopts a low-temperature nanocrystallization lithium-rich liquid technology to realize collaborative coupling of one-step preparation of battery-grade lithium carbonate and CO2 high-valued utilization, and the nanocrystallization lithium-rich liquid carried by CO2 has larger reaction specific surface area and smaller bubble particle size. The problem that CO2 overflows from a solution in an existing bubble tower is avoided, the problem that the particle size of lithium carbonate generated through an existing method is large is solved, and the industrial process is shortened while the CO2 utilization rate is greatly increased.

Description

Technical Field:

[0001] The present invention relates to the technical field of preparation of battery-grade lithium carbonate, and particularly to a method for preparing battery-grade lithium carbonate from nano-lithium-rich liquid. Background Art:

[0002] In recent years, hydrometallurgy technology has been used to leach lithium ions from waste lithium batteries, lithium ores and lithium brines to obtain lithium-rich liquid. The lithium-rich liquid is obtained through various methods to obtain the target lithium salt, so as to realize the recycling of lithium resources and reduce the mining of natural lithium ores. Preparing lithium-rich liquid is an essential step in the extraction of lithium by hydrometallurgy. Such lithium-rich liquid contains a high concentration of lithium ions. The main method for industrial production of lithium carbonate is to react with sodium carbonate salt to prepare lithium carbonate. The reaction temperature for preparing lithium carbonate is about 90 °C. Precipitating lithium ions with sodium carbonate solution will introduce a large amount of sodium elements. By carbonizing and pyrolyzing lithium carbonate, and then washing and removing sodium, the lithium concentration will be reduced, resulting in a very low yield. On the other hand, the efficiency of bubbling carbon dioxide into the tower in a circulating manner is very low. The prepared lithium carbonate needs to be further sieved and ground to prepare battery-grade lithium carbonate to increase its value. And over a long time, it will corrode the bubbling tower and introduce impurities, while the polytetrafluoro bubbling tower cannot withstand high temperatures for a long time. The large loss, low purity and coarse particle size increase the economic cost of preparing battery-grade lithium carbonate from lithium-rich liquid, and reduce the environmental benefit of capturing CO 2 2.

[0003] Therefore, it is necessary to develop a more appropriate method to synergistically recycle metals and capture greenhouse gases to prepare battery-grade lithium carbonate. Summary of the Invention:

[0004] The purpose of the present invention is to provide a method for preparing battery-grade lithium carbonate from nano-lithium-rich liquid, which solves the problems of long process, introduction of impurity metals and large particle size in the prior art for preparing battery-grade lithium carbonate by reacting with sodium carbonate salt, and also solves the problems of low efficiency in preparing lithium carbonate slurry by using CO 2 2 and low product purity.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for preparing battery-grade lithium carbonate from nano-lithium-rich liquid, the method comprising the following steps:

[0007] (1) Nano-lithium-rich liquid: Introduce CO 2 into the negatively pressure-sucked lithium-rich liquid until it reaches supersaturation. The circulating introduction time of CO 2 is 13-20 min, preferably 16-19 min, to nano-lithium-rich nano-liquid by gas-liquid blending method; the lithium-rich liquid is selected from one of waste lithium-ion battery recycling technology, lithium ore lithium extraction technology and brine lithium extraction technology; preferably, the lithium-rich liquid is selected from waste lithium-ion battery recycling technology;

[0008] (2) Preparation of battery-grade lithium carbonate: Continuing to introduce CO into the lithium-rich nano-liquid obtained in step (1). 2 CO 2 is introduced at a flow rate of 100 - 600 ml / min, preferably 200 - 500 ml / min. The introduction time of CO 2 is 15 - 30 min, preferably 18 - 27 min. The bubble diameter in the lithium-rich nano-liquid is 50 - 85 nm, preferably 55 - 80 nm. At the same time, saturated ammonia water and the lithium-rich nano-liquid prepared in step (1) are placed in a polytetrafluoro reaction vessel, stirred and heated for reaction. Adjust the pH of the lithium-rich nano-liquid to 10.5 - 13, preferably 11 - 12.5. The concentration of lithium in the lithium-rich nano-liquid is 10 - 35 g / L, preferably 15 - 30 g / L. The stirring speed is 100 - 175 rpm, preferably 115 - 160 rpm. The heating temperature is 30 - 80 °C, preferably 40 - 70 °C. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.1 - 1:1.6 m / m, preferably 1:1.2 - 1:1.5 m / m. And ammonia water is slowly added throughout the reaction process. The flow rate of ammonia water is 15 - 25 ml / min, preferably 17 - 23 ml / min. After the reaction, vacuum filtration and drying are carried out to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0009] Preferably, the CO 2 comes from the CO emitted after the combustion of natural gas hydrate, fossil energy or biomass 2 , or the CO obtained by air compression 2 .

[0010] In step (2), saturated ammonia water can be replaced by one of saturated sodium hydroxide or saturated sodium bicarbonate solution, and more preferably saturated ammonia water, which is more environmentally friendly.

[0011] The beneficial effects of the present invention are as follows:

[0012] 1. The present invention realizes the synergistic coupling of one-step preparation of battery-grade lithium carbonate and high-value utilization of CO by using the low-temperature nano-lithium-rich liquid technology. The nano-lithium-rich liquid carried by CO has a larger reaction specific surface area, avoiding the overflow of existing CO from the solution in the bubble column, and greatly improving the utilization rate of CO. 2 CO 2 The carried nano-lithium-rich liquid has a larger reaction specific surface area, avoiding the overflow of existing CO 2 from the solution, and greatly improving the utilization rate of CO 2 .

[0013] 2. The present invention utilizes the greenhouse gas CO 2As a carbonization method for precipitating lithium carbonate, it avoids multiple steps such as adding sodium carbonate solution for high-temperature preparation, secondary carbonization pyrolysis, and multi-stage screening, avoids problems such as a large amount of water resource waste, low lithium conversion rate, long purification steps, and secondary granulation, avoids expanding the reaction equipment by adding sodium carbonate solution, reduces the solvent usage amount in the reaction process, washing and sodium removal of deionized water products, avoids lithium loss during the washing process, and increases environmental benefits and economy.

[0014] 3. The CO in the present invention 2 The nano-sized lithium-rich liquid carried by it has nano-sized bubbles. After the reaction, it can directly prepare lithium carbonate meeting the particle size standard for battery grade without further crushing, grinding, screening, or regulating the particle size to achieve the battery-grade lithium carbonate standard, reducing industrial steps. And compared with the micro-nano bubble technology, it has more reaction interfaces, greatly improving the reaction rate; moreover, the internal energy in the nano-bubbles is greater, which can reduce the energy consumption for heating the reaction system and has the potential for industrial expansion.

[0015] 4. The diameter-to-height ratio of the polytetrafluoro reaction vessel in the present invention is 1:1.1 - 1:1.6 m / m, which solves the problems of difficult product collection, a large amount of microplastics entering the product, and reducing the product purity. Description of the Drawings:

[0016] Figure 1 It is the XRD pattern of lithium carbonate obtained in Example 3. Detailed Embodiments:

[0017] The following is a further description of the present invention, rather than a limitation to the present invention.

[0018] Example 1: A method for preparing battery-grade lithium carbonate from nano-sized lithium-rich liquid

[0019] It includes the following steps:

[0020] (1) Nano-sized lithium-rich liquid: CO 2 is introduced into the lithium-rich liquid sucked in under negative pressure (the lithium-rich liquid is selected from waste lithium-ion battery recycling technologies, see Publication (Announcement) No.: CN115072921B, Publication (Announcement) No.: CN115744992B) until it reaches the supersaturation value. The CO 2 is circulated and introduced for 13 minutes, and the lithium-rich nano-liquid obtained by the gas-liquid blending method for nano-sizing the lithium-rich liquid has bubble particle sizes less than 0.1 μm.

[0021] (2) Preparing battery-grade lithium carbonate: The lithium-rich nano-liquid obtained in step (1) is continuously introduced with CO 2React at a flow rate of 100 ml / min for 15 min. The bubble size in the lithium-rich nano-liquid is 50 nm. At the same time, introduce saturated ammonia water to adjust the pH of the lithium-rich nano-liquid to 10.5, and the lithium concentration in the lithium-rich nano-liquid is 10 g / L. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.1 m / m, the stirring speed is 100 rpm, the temperature is 30 °C, and the flow rate of the saturated alkaline solution slowly added throughout the reaction is 15 ml / min. After the reaction, perform vacuum filtration and drying to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0022] Example 2: A method for preparing battery-grade lithium carbonate from nano-lithium-rich liquid

[0023] Comprising the following steps:

[0024] (1) Nano-lithium-rich liquid: Introduce CO 2 into the negatively pressure-sucked lithium-rich liquid to reach supersaturation. The circulation time of CO 2 is 20 min, and the lithium-rich nano-liquid obtained by nano-sizing the lithium-rich nano-liquid by the gas-liquid blending method contains bubbles with a size less than 0.1 μm.

[0025] (2) Prepare battery-grade lithium carbonate: Continue to introduce CO 2 into the lithium-rich nano-liquid obtained in step (1) at a flow rate of 600 ml / min for reaction. The reaction time is 30 min, and the bubble size in the lithium-rich nano-liquid is 85 nm. At the same time, introduce saturated ammonia water to adjust the pH of the lithium-rich nano-liquid to 13, and the lithium concentration in the lithium-rich nano-liquid is 35 g / L. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.6 m / m, the stirring speed is 175 rpm, the temperature is 80 °C, and the flow rate of the saturated alkaline solution slowly added throughout the reaction is 25 ml / min. After the reaction, perform vacuum filtration and drying to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0026] Example 3: A method for preparing battery-grade lithium carbonate from nano-lithium-rich liquid

[0027] Comprising the following steps:

[0028] (1) Nano-lithium-rich liquid: Introduce CO 2 into the negatively pressure-sucked lithium-rich liquid to reach supersaturation. The circulation time of CO 2 is 16 min, and the lithium-rich nano-liquid obtained by nano-sizing the lithium-rich nano-liquid by the gas-liquid blending method contains bubbles with a size less than 0.1 μm.

[0029] (2) Prepare battery-grade lithium carbonate: Continue to introduce CO 2React at a flow rate of 200 ml / min for 18 min. The bubble size in the lithium-rich nano-liquid is 55 nm. Meanwhile, introduce saturated ammonia water to adjust the pH of the lithium-rich nano-liquid to 11, and the lithium concentration in the lithium-rich nano-liquid is 15 g / L. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.2 m / m, the stirring speed is 115 rpm, the temperature is 40 °C, and the flow rate of the saturated alkaline solution slowly added throughout the reaction is 17 ml / min. After the reaction, perform vacuum filtration and drying to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0030] Example 4: A method for preparing battery-grade lithium carbonate from nano-sized lithium-rich liquid

[0031] It includes the following steps:

[0032] (1) Nano-sized lithium-rich liquid: Introduce CO 2 into the negatively pressure-sucked lithium-rich liquid until it reaches supersaturation. The CO 2 circulation time is 19 min. The lithium-rich nano-liquid obtained by nano-sizing the lithium-rich nano-liquid by the gas-liquid blending method contains bubble sizes less than 0.1 μm.

[0033] (2) Prepare battery-grade lithium carbonate: Continue to introduce CO 2 into the lithium-rich nano-liquid obtained in step (1) at a flow rate of 500 ml / min for reaction. The reaction time is 27 min, and the bubble size in the lithium-rich nano-liquid is 80 nm. Meanwhile, introduce saturated ammonia water to adjust the pH of the lithium-rich nano-liquid to 12.5, and the lithium concentration in the lithium-rich nano-liquid is 30 g / L. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.5 m / m, the stirring speed is 160 rpm, the temperature is 70 °C, and the flow rate of the saturated alkaline solution slowly added throughout the reaction is 23 ml / min. After the reaction, perform vacuum filtration and drying to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0034] Example 5: A method for preparing battery-grade lithium carbonate from nano-sized lithium-rich liquid

[0035] It includes the following steps:

[0036] (1) Nano-sized lithium-rich liquid: Introduce CO 2 into the negatively pressure-sucked lithium-rich liquid until it reaches supersaturation. The CO 2 circulation time is 17 min. The lithium-rich nano-liquid obtained by nano-sizing the lithium-rich nano-liquid by the gas-liquid blending method contains bubble sizes less than 0.1 μm.

[0037] (2) Prepare battery-grade lithium carbonate: Continue to introduce CO 2React at a flow rate of 300 ml / min for 21 min. The bubble size in the lithium-rich nano-liquid is 60 nm. Meanwhile, introduce saturated ammonia water to adjust the pH of the lithium-rich nano-liquid to 11.5, and the lithium concentration in the lithium-rich nano-liquid is 20 g / L. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.3 m / m, the stirring speed is 130 rpm, the temperature is 50 °C, and the flow rate of the saturated alkaline solution is slowly added throughout the reaction process at 19 ml / min. After the reaction, perform vacuum filtration and drying to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0038] Example 6: A method for preparing battery-grade lithium carbonate from nano-sized lithium-rich liquid

[0039] It includes the following steps:

[0040] (1) Nano-sized lithium-rich liquid: Introduce CO 2 into the negatively pressured-inhaled lithium-rich liquid until it reaches supersaturation. The circulation time of CO 2 is 18 min. The lithium-rich nano-liquid obtained by nano-sizing the lithium-rich nano-liquid by the gas-liquid blending method contains bubble sizes less than 0.1 μm.

[0041] (2) Prepare battery-grade lithium carbonate: Continue to introduce CO 2 into the lithium-rich nano-liquid obtained in step (1) at a flow rate of 400 ml / min for reaction. The reaction time is 24 min, and the bubble size in the lithium-rich nano-liquid is 75 nm. Meanwhile, introduce saturated ammonia water to adjust the pH of the lithium-rich nano-liquid to 12, and the lithium concentration in the lithium-rich nano-liquid is 25 g / L. The diameter-to-height ratio of the polytetrafluoro reaction vessel is 1:1.4 m / m, the stirring speed is 145 rpm, the temperature is 60 °C, and the flow rate of the saturated alkaline solution is slowly added throughout the reaction process at 21 ml / min. After the reaction, perform vacuum filtration and drying to obtain battery-grade lithium carbonate, and the tail liquid is recycled into the lithium-rich liquid.

[0042] Comparative Example 1: A method for preparing battery-grade lithium carbonate from nano-sized lithium-rich liquid

[0043] Refer to Example 2, the difference is that in step (1), the lithium-rich liquid is not nano-sized, and the remaining processes and parameters are the same as those in Example 2.

[0044] Since the lithium-rich liquid was not nano-sized in Comparative Example 1, a large amount of CO 2 bubbled out from the solution, and it was necessary to add a circulating gas path device and a drying device. Moreover, the conversion rate of CO 2 was extremely low. Due to the too large gas bubbles in the lithium-rich liquid, a large amount of it sputtered onto the reactor wall, resulting in uneven reaction and high loss of lithium elements on the wall. Also, the too large bubble size caused the particle size of the lithium carbonate product to be large particles, which did not meet the requirements of battery-grade lithium carbonate.

[0045] Comparative Example 2: A method for preparing battery-grade lithium carbonate from nano-lithium-rich solution

[0046] Referring to Example 2, the difference is that in step (2), the diameter-to-height ratio of the polytetrafluoroethylene reaction vessel is less than 1:1.1, and the rest of the process and parameters are the same as those in Example 2.

[0047] Since the diameter-to-height ratio of the reaction vessel in Comparative Example 2 is less than 1:1.1 and is 1:1, the gas-liquid two-phase flow and temperature distribution are uneven, and the temperature of the reaction vessel wall is relatively high while the temperature near the center position is relatively low. A large amount of lithium carbonate accumulates at the discharge port of the lithium-rich nano-liquid and on the wall of the polytetrafluoroethylene reactor, resulting in difficult product collection, and a large amount of microplastics enter the product, reducing the product purity.

[0048] The lithium carbonate purity and particle size compliance rates in Examples 1-6 and Comparative Examples 1-2 are shown in Table 1.

[0049] Table 1

[0050]

[0051] The description of the above embodiments is only used to help understand the technical solution and its core idea of the present invention. It should be noted that for those skilled in the art of this technology, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing battery-grade lithium carbonate from nano-lithium-rich liquid, characterized in that: The method comprises the following steps: (1) Nano-forming lithium-rich liquid: CO2 is introduced into the lithium-rich liquid sucked by negative pressure to a supersaturated value, and the CO2 circulation time is 13 to 20 minutes, and the lithium-rich liquid is nano-formed by gas-liquid mixing method; the lithium-rich liquid is selected from one of the waste lithium-ion battery recovery technology, ore lithium extraction technology and brine lithium extraction technology; (2) Preparation of battery-grade lithium carbonate: The lithium-rich nano-liquid obtained in step (1) is continuously passed with CO2, the CO2 flow rate is 100-600 ml / min, the CO2 passing time is 15-30 min, the bubble particle size in the lithium-rich nano-liquid is 50-85 nm, and saturated ammonia water is simultaneously passed with the lithium-rich nano-liquid prepared in step (1) and placed in a polytetrafluoroethylene reaction vessel, stirred and heated for reaction, the pH of the lithium-rich nano-liquid is adjusted to 10.5-13, the lithium concentration in the lithium-rich nano-liquid is 10-35 g / L, the stirring speed is 100-175 rpm, the heating temperature is 30-80° C., the diameter ratio of the polytetrafluoroethylene reaction vessel is 1:1.1-1:1.6 m / m, and ammonia water is slowly added during the whole reaction process, the ammonia water flow rate is 15-25 ml / min, and after the reaction is completed, vacuum filtration and drying are performed to obtain battery-grade lithium carbonate, and the tail liquid is circulated into the lithium-rich liquid.

2. The method according to claim 1, characterized in that Step (1) CO2 is introduced into the lithium-rich solution sucked under negative pressure to a supersaturated value, and the CO2 circulation time is 16-19 minutes.

3. The method according to claim 1, characterized in that The CO2 comes from natural gas hydrates, CO2 emitted after fossil energy or biomass combustion, or CO2 obtained by air compression.

4. The method according to claim 1, characterized in that: The step (2) comprises: continuing to pass CO2 through the lithium-rich nano-liquid obtained in the step (1), wherein the CO2 flow rate is 200-500 ml / min, the CO2 passing time is 18-27 min, the bubble particle size in the lithium-rich nano-liquid is 55-80 nm, and simultaneously passing saturated ammonia water and the lithium-rich nano-liquid prepared in the step (1) into a polytetrafluoroethylene reaction vessel, stirring and heating for reaction, adjusting the pH value of the lithium-rich nano-liquid to 11-12.5, the lithium concentration in the lithium-rich nano-liquid to 15-30 g / L, the stirring speed is 115-160 rpm, the heating temperature is 40-70° C., the diameter ratio of the polytetrafluoroethylene reaction vessel is 1:1.2-1:1.5 m / m, and slowly adding ammonia water during the whole reaction process, wherein the ammonia water flow rate is 17-23 ml / min, vacuum filtration and drying are performed after the reaction to obtain battery-grade lithium carbonate, and the tail liquid is circulated into the lithium-rich liquid.

5. The method according to claim 1, characterized in that: In step (2), the saturated aqueous ammonia is replaced with a saturated sodium hydroxide solution or a saturated sodium bicarbonate solution.

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