New process for extracting lithium from salt lake with efficient and balanced utilization of energy

Abstract

The invention discloses a novel salt lake lithium extraction process for efficient and balanced utilization of energy, and belongs to the technical field of preparation of new energy materials. The process comprises the following heat recovery and utilization steps: S1, low-grade heat recovery: adopting raw water of production water as cooling water, and recovering heat in the following procedures: an adsorption lithium extraction procedure, an electrodialysis procedure and a nanofiltration reverse osmosis procedure; s2, medium-grade heat recovery: feeding the production water with recovered low-grade heat or / and reverse osmosis fresh water as a byproduct of the nanofiltration reverse osmosis process into the following processes for continuously absorbing heat: a lithium carbonate process cooling section, an air compression process, a concentration process and a mother liquor recovery process; and S3, heat utilization: taking the production water or / and reverse osmosis fresh water from which the medium-grade heat is recovered as thermal desorption water, and feeding the thermal desorption water into an adsorption lithium extraction process. According to the invention, the application of a circulating-water-free cooling system is realized in the salt lake lithium extraction process for the first time, the investment cost and the occupied area are reduced, and the subversive innovation of the traditional process is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy material preparation, and specifically relates to a new process for extracting lithium from salt lakes with efficient and balanced energy utilization. Background Art

[0002] Lithium extraction from salt lakes is currently the primary source of battery-grade basic lithium salts. Its core process involves extracting lithium from lithium-containing brines of a certain grade through adsorption and extraction techniques for use in the production of battery-grade lithium carbonate and other products. The salt lake lithium extraction process requires cooling at multiple stages, depending on process requirements. These include adsorption extraction, nanofiltration reverse osmosis, electrodialysis, cooling of the finished product from lithium carbonate drying and calcination, extraction of lithium from lithium carbonate mother liquor, and air compressor cooling. Heat from these processes must be effectively removed. At the same time, significant heating is required within the salt lake lithium extraction process, such as heating the desorption water in the adsorption extraction stage. Therefore, energy balance within the salt lake lithium extraction system is crucial and a key tool for energy conservation and emission reduction.

[0003] Current lithium extraction processes from salt lakes typically use a circulating water cooling system to cool the material while simultaneously using steam to heat the liquid. However, this approach increases investment costs and operating energy consumption, while also resulting in a waste of water and energy resources, particularly in the dry and cold northern regions.

[0004] Therefore, developing a new process for extracting lithium from salt lakes with efficient and balanced energy utilization is of great significance for reducing production costs and improving resource utilization efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a new process for extracting lithium from salt lakes with efficient and balanced energy utilization, which can improve resource utilization efficiency and reduce production costs.

[0006] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0007] The present invention discloses a new process for extracting lithium from salt lakes with efficient and balanced energy utilization, comprising a lithium extraction process by adsorption, an electrodialysis process, a nanofiltration reverse osmosis process, a lithium carbonate process, an air pressure process, a concentration process, and a mother liquor recovery process. The process includes the following heat recovery steps:

[0008] S1. Low-grade heat recovery: Using produced water as cooling water, recover heat from at least one of the following processes: adsorption lithium extraction process, electrodialysis process, and nanofiltration reverse osmosis process;

[0009] S2. Medium-grade heat recovery: The produced water from which low-grade heat has been recovered and / or the reverse osmosis fresh water produced as a by-product of the nanofiltration reverse osmosis process are fed to at least one of the following processes for further heat absorption: a lithium carbonate process, an air compression process, a concentration process, and a mother liquor recovery process;

[0010] S3. Heat utilization: The produced water and / or reverse osmosis fresh water with recovered medium-grade heat are sent to the adsorption lithium extraction process as thermal desorption water.

[0011] In some embodiments of the present invention, the produced water from which low-grade heat is recovered is fed into the cooling section of the lithium carbonate process and the air compression process to recover medium-grade heat; the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process is fed into the concentration process and the mother liquor recovery process to recover medium-grade heat; the produced water from which medium-grade heat is recovered and the reverse osmosis fresh water are combined and fed into the adsorption lithium extraction process as thermal desorption water.

[0012] In some embodiments of the present invention, when recovering low-grade heat, in the heat recovery step of the adsorption lithium extraction process, the production water is used to exchange heat with the qualified adsorption liquid, and the qualified adsorption liquid is reduced to 25-30°C before entering the nanofiltration reverse osmosis process; preferably, the production water and the qualified adsorption liquid are heat exchanged through a heat exchanger;

[0013] In the heat recovery step of the nanofiltration reverse osmosis process, the production water and brine are heat exchanged to reduce the temperature of the brine to 25-30°C; preferably, the production water and brine are heat exchanged using a heat exchanger;

[0014] In the heat recovery step of the electrodialysis process, the production raw water and the electrodialysis concentrate are used for heat exchange, and the electrodialysis concentrate is cooled by the production raw water to 30-35°C; preferably, a heat exchanger is set on the electrodialysis concentrate side, and the production raw water and the electrodialysis concentrate are exchanged with heat through the heat exchanger.

[0015] In some embodiments of the present invention, when recovering medium-grade heat, in the heat recovery step of the cooling section of the lithium carbonate process, the produced water from which low-grade heat has been recovered or / and the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process are indirectly heat-exchanged with the high-temperature lithium carbonate to cool the lithium carbonate solid to 60° C. Preferably, the medium-grade heat is recovered by indirect heat exchange in a lithium carbonate solid conveying screw, a cooling drum, or a powder flow cooler.

[0016] In the heat recovery step of the air compression process, the compression heat of the air compressor is removed by using produced water with recovered low-grade heat or reverse osmosis fresh water generated in the nanofiltration reverse osmosis process, and the compressed air is cooled to 30-50°C, thereby recovering medium-grade heat.

[0017] In the heat recovery step of the concentration process, produced water from which low-grade heat has been recovered and / or reverse osmosis fresh water produced in the nanofiltration reverse osmosis process are used to cool the concentrated evaporative tail gas, steam compressor lubricating oil, and vacuum pump liquid ring through a heat exchanger, thereby recovering medium-grade heat; preferably, the concentrated evaporative tail gas is cooled to 30-40°C, and the vacuum pump liquid ring is cooled to 30-50°C; preferably, the concentrated evaporative tail gas and vacuum pump liquid ring are cooled through a plate heat exchanger;

[0018] In the heat recovery step of the mother liquor recovery, the produced water from which low-grade heat has been recovered and / or the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process are used to exchange heat with the high-temperature lithium precipitation mother liquor through a heat exchanger to recover medium-grade heat; preferably, heat exchange with the high-temperature lithium precipitation mother liquor is carried out through a plate heat exchanger.

[0019] In some embodiments of the present invention, the temperature of the produced water from which low-grade heat is recovered is 25-32°C.

[0020] In some embodiments of the present invention, the temperature of the produced water from which the medium-grade heat is recovered is 30-40°C.

[0021] In some embodiments of the present invention, the thermal desorption temperature is 30-42°C, preferably 30-38°C.

[0022] In some embodiments of the present invention, the temperature of the reverse osmosis fresh water produced by the nanofiltration reverse osmosis process is 25-35°C.

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

[0024] The present invention is scientifically designed and ingeniously conceived. It realizes the application of a non-circulating water cooling system in the salt lake lithium extraction process for the first time, reduces investment costs and floor space, and achieves disruptive innovation to traditional processes.

[0025] The present invention uses produced water and reverse osmosis fresh water as cooling water, and uses high-temperature water after heat recovery as thermal desorption water, thereby achieving efficient and balanced utilization of energy.

[0026] The present invention first recovers low-grade heat and then recovers medium-grade heat, and achieves maximum utilization of cooling water through a step-cooling method, thereby improving cooling efficiency.

[0027] The present invention improves the operating efficiency of the entire salt lake lithium extraction system, achieves the goal of energy conservation and emission reduction, and has very good promotion value for areas lacking water and steam resources.

[0028] In summary, the process of the present invention not only reduces investment costs and floor space, but also improves resource utilization efficiency, reduces energy consumption and production costs, and has very good promotion value for areas lacking water and steam resources. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Attachment Figure 1 It is a process flow chart of the present invention.

[0030] The names corresponding to the reference numerals are: 101 - first conveying pipeline, 102 - second conveying pipeline. DETAILED DESCRIPTION

[0031] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0032] Example 1

[0033] As attached Figure 1 As shown, the present invention discloses a new process for extracting lithium from salt lakes with efficient and balanced energy utilization, including a lithium extraction process by adsorption, an electrodialysis process, a nanofiltration reverse osmosis process, a lithium carbonate process, an air compression process, a concentration process, and a mother liquor recovery process, including the following steps:

[0034] S1. Low-grade heat recovery

[0035] The produced raw water (temperature of 9-20°C) is used as cooling water to recover heat from at least one of the following processes: adsorption lithium extraction process, electrodialysis process, and nanofiltration reverse osmosis process.

[0036] In the heat recovery step of the adsorption lithium extraction process, the production water and the qualified adsorption liquid are exchanged through a heat exchanger to cool the qualified adsorption liquid to 25-30℃ before entering the nanofiltration reverse osmosis process;

[0037] In the heat recovery step of the nanofiltration reverse osmosis process, the produced water and brine are exchanged through a heat exchanger to reduce the temperature of the brine to 25-30°C;

[0038] In the heat recovery step of the electrodialysis process, production raw water and electrodialysis concentrated liquid are used for heat exchange, and the electrodialysis concentrated liquid is cooled by the production water raw water to a temperature of 30-35°C. Specifically, a heat exchanger is set on the electrodialysis concentrated liquid side, and the production water raw water and electrodialysis concentrated liquid are heat exchanged through the heat exchanger.

[0039] S2. Medium-grade heat recovery

[0040] The produced water (temperature of 25-32°C) from which low-grade heat has been recovered is fed to at least one of the following processes to continue absorbing heat: a lithium carbonate process, an air compression process, a concentration process, and a mother liquor recovery process;

[0041] In the heat recovery step of the lithium carbonate process, the produced water from which low-grade heat has been recovered is indirectly heat-exchanged with the high-temperature lithium carbonate; preferably, the intermediate-grade heat is recovered by indirect heat exchange in a lithium carbonate solid conveying screw, a cooling drum, or a powder flow cooler;

[0042] In the heat recovery step of the air compression process, the compression heat of the air compressor is removed by using the produced water with recovered low-grade heat, thereby recovering the medium-grade heat;

[0043] In the heat recovery step of the concentration process, the produced water with recovered low-grade heat is used to cool the concentrated evaporation tail gas and the liquid ring of the vacuum pump through a plate heat exchanger to recover the medium-grade heat;

[0044] In the heat recovery step of the mother liquor recovery, the produced water with recovered low-grade heat is used to exchange heat with the high-temperature lithium precipitation mother liquor through a plate heat exchanger to recover medium-grade heat;

[0045] S3. Heat utilization: Add a small amount of low-temperature production water (temperature 9-20°C) to the produced water (temperature 30-40°C) with recovered medium-grade heat, mix them and send them into the adsorption lithium extraction process as thermal desorption water (temperature 30-38°C).

[0046] Example 2

[0047] As attached Figure 1 As shown, the present invention discloses a new process for extracting lithium from salt lakes with efficient and balanced energy utilization, including a lithium extraction process by adsorption, an electrodialysis process, a nanofiltration reverse osmosis process, a lithium carbonate process, an air compression process, a concentration process, and a mother liquor recovery process, including the following steps:

[0048] S1. Low-grade heat recovery

[0049] The raw water (temperature of 9-20°C) is used as cooling water to recover heat from the following processes: adsorption lithium extraction process, electrodialysis process, and nanofiltration reverse osmosis process.

[0050] In the heat recovery step of the adsorption lithium extraction process, the production water and the qualified adsorption liquid are exchanged through a heat exchanger to cool the qualified adsorption liquid to 25-30°C; the cooled qualified adsorption liquid enters the nanofiltration reverse osmosis process;

[0051] In the heat recovery step of the nanofiltration reverse osmosis process, the produced water (temperature of 9-20°C) is used to exchange heat with the brine through a heat exchanger to reduce the temperature of the brine to 25-30°C;

[0052] In the heat recovery step of the electrodialysis process, production raw water (temperature of 9-20°C) is used for heat exchange with the electrodialysis concentrate to cool the electrodialysis concentrate to 30-35°C. Specifically, a heat exchanger is set on the electrodialysis concentrate side, and the production raw water and the electrodialysis concentrate are heat exchanged through the heat exchanger.

[0053] S2. Medium-grade heat recovery

[0054] The produced water (temperature of 25-32°C) from which low-grade heat has been recovered is sent to the following processes to continue absorbing heat: the lithium carbonate process and the air compression process; the reverse osmosis fresh water (temperature of 25-35°C) produced in the nanofiltration reverse osmosis process is sent to the concentration process and the mother liquor recovery process to recover medium-grade heat;

[0055] In the heat recovery step of the lithium carbonate process, the produced water with recovered low-grade heat is indirectly exchanged with the high-temperature lithium carbonate; specifically, the intermediate-grade heat is recovered by indirect heat exchange in the lithium carbonate solid conveying screw, cooling drum, or powder flow cooler;

[0056] In the heat recovery step of the air compression process, the compression heat of the air compressor is removed by using produced water with recovered low-grade heat, and the compressed air is cooled to 30-50°C, thereby recovering medium-grade heat.

[0057] In the heat recovery step of the concentration process, reverse osmosis fresh water is used to cool the concentrated evaporation tail gas and the vacuum pump liquid ring through a plate heat exchanger to recover the intermediate heat; specifically, the concentrated evaporation tail gas is cooled to 30-40°C, and the vacuum pump liquid ring is cooled to 30-50°C;

[0058] In the heat recovery step of the mother liquor recovery, reverse osmosis fresh water is used to exchange heat with the high-temperature lithium precipitation mother liquor through a plate heat exchanger, and the lithium precipitation mother liquor is cooled to 35-40°C to recover the intermediate heat;

[0059] S3. Heat utilization: The produced water (temperature of 30-40°C) with recovered medium-grade heat and the reverse osmosis fresh water (temperature of 30-40°C) are combined, and a small amount of low-temperature produced raw water (temperature of 9-20°C) is added and then sent to the adsorption lithium extraction process as thermal desorption water (temperature of 30-38°C).

[0060] Example 3

[0061] As attached Figure 1 As shown, the present invention discloses a new process for extracting lithium from salt lakes with efficient and balanced energy utilization, including a lithium extraction process by adsorption, an electrodialysis process, a nanofiltration reverse osmosis process, a lithium carbonate process, an air compression process, a concentration process, and a mother liquor recovery process, including the following steps:

[0062] S1. Low-grade heat recovery

[0063] The raw water (temperature of 9-20°C) is used as cooling water to recover heat from the following processes: adsorption lithium extraction process, electrodialysis process, and nanofiltration reverse osmosis process.

[0064] In the heat recovery step of the adsorption lithium extraction process, the production water and the qualified adsorption liquid are exchanged through a heat exchanger to cool the qualified adsorption liquid to 25-30°C; the cooled qualified adsorption liquid enters the nanofiltration reverse osmosis process;

[0065] In the heat recovery step of the nanofiltration reverse osmosis process, the produced water (temperature of 9-20°C) is used to exchange heat with the brine through a heat exchanger to reduce the temperature of the brine to 25-30°C;

[0066] In the heat recovery step of the electrodialysis process, production raw water (temperature of 9-20°C) is used for heat exchange with the electrodialysis concentrate to cool the electrodialysis concentrate to 30-35°C. Specifically, a heat exchanger is set on the electrodialysis concentrate side, and the production raw water and the electrodialysis concentrate are heat exchanged through the heat exchanger.

[0067] S2. Medium-grade heat recovery

[0068] The produced water, from which low-grade heat has been recovered, flows through first pipeline 101 into the following processes: lithium carbonate, air compression, concentration, and mother liquor recovery. The reverse osmosis fresh water produced by the nanofiltration reverse osmosis process is discharged from the nanofiltration reverse osmosis process through second pipeline 102, which is connected to first pipeline 101 via a pipeline. Both first and second pipelines 101, 102, are equipped with valves.

[0069] The lithium carbonate process, air compression process, concentration process, and mother liquor process can switch the type of cooling water used and adjust its flow rate according to the cooling water usage and water quality. The cooling water types are as follows: produced water with low-grade heat recovery, reverse osmosis fresh water, or a mixture of produced water with low-grade heat recovery and reverse osmosis fresh water;

[0070] Specifically:

[0071] In the heat recovery step of the lithium carbonate process, the cooling water is indirectly heat-exchanged with the high-temperature lithium carbonate; specifically, the heat is recovered by indirect heat exchange in the lithium carbonate solid conveying screw or cooling drum or powder flow cooler;

[0072] In the heat recovery step of the air compression process, cooling water is used to remove the compression heat of the air compressor and cool the compressed air to 30-50°C, thereby recovering the heat of the medium.

[0073] In the heat recovery step of the concentration process, cooling water is used to cool the concentrated evaporation tail gas and the vacuum pump liquid ring through a plate heat exchanger to recover the intermediate heat; specifically, the concentrated evaporation tail gas is cooled to 30-40°C, and the vacuum pump liquid ring is cooled to 30-50°C;

[0074] In the heat recovery step of the mother liquor recovery, cooling water is used to exchange heat with the high-temperature lithium precipitation mother liquor through a plate heat exchanger to cool the lithium precipitation mother liquor to 35-40°C to recover the intermediate heat;

[0075] S3. Heat utilization: The cooling water (temperature of 30-40°C) with recovered medium-grade heat is combined and a small amount of low-temperature production water (temperature of 9-20°C) is added to it and then sent to the adsorption lithium extraction process as thermal desorption water (temperature of 30-38°C).

[0076] The present invention uses the supplementary water of lithium adsorption desorption water, that is, the production water and the fresh water produced as a by-product of reverse osmosis, as the source, and indirectly exchanges heat with the materials that need heat exchange in the process. The temperature of the production water and the reverse osmosis fresh water reaches the temperature requirement of the desorption water, thereby avoiding the consumption of circulating water. At the same time, the materials that need to be cooled are cooled, killing two birds with one stone. In the process of the present invention, the heat energy that may be regarded as waste is effectively utilized in a step-by-step manner, realizing the maximum recovery and reuse of energy. It ensures the rational use of cooling water and thermal desorption water, reduces the dependence on external cooling water resources and steam resources, and reduces energy consumption and production costs.

[0077] By adopting the process of this embodiment, taking the extraction of lithium from salt lake brine with a lithium concentration of 0.2 g / L as an example, for every 10,000 tons of lithium carbonate produced, about 4.18 million tons of circulating cooling water and about 72,000 tons of steam can be saved.

[0078] The above is only a preferred embodiment of the invention and does not constitute any formal limitation on the invention. Based on the technical essence of the invention and within the spirit and principles of the invention, any simple modification, equivalent replacement and improvement of the above embodiment shall still fall within the scope of protection of the technical solution of the invention.

Claims

1. A new process for extracting lithium from salt lakes with efficient and balanced energy utilization, comprising a lithium extraction process by adsorption, an electrodialysis process, a nanofiltration reverse osmosis process, a lithium carbonate process, an air compression process, a concentration process, and a mother liquor recovery process, characterized in that: The process includes the following heat recovery steps: S1. Low-grade heat recovery: Using produced water as cooling water, recover heat from at least one of the following processes: adsorption lithium extraction process, electrodialysis process, and nanofiltration reverse osmosis process; S2. Medium-grade heat recovery: The produced water from which low-grade heat has been recovered and / or the reverse osmosis fresh water produced as a by-product of the nanofiltration reverse osmosis process are fed into at least one of the following processes to continue absorbing heat: the lithium carbonate process, the air compression process, the concentration process, and the mother liquor recovery process; S3. Heat utilization: The produced water from which medium-grade heat has been recovered and / or the reverse osmosis fresh water are fed into the adsorption lithium extraction process as thermal desorption water.

2. The new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to claim 1, characterized in that: The produced water from which low-grade heat has been recovered is sent to the cooling section of the lithium carbonate process and the air compression process to recover medium-grade heat; the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process is sent to the concentration process and the mother liquor recovery process to recover medium-grade heat; the produced water from which medium-grade heat has been recovered and the reverse osmosis fresh water are combined and sent to the adsorption lithium extraction process as thermal desorption water.

3. A new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to claim 1 or 2, characterized in that: When recovering low-grade heat, in the heat recovery step of the adsorption lithium extraction process, the production water raw water is used to exchange heat with the adsorption qualified liquid, and the adsorption qualified liquid is reduced to 25-30°C before entering the nanofiltration reverse osmosis process; preferably, the production water raw water and the adsorption qualified liquid are heat exchanged through a heat exchanger; In the heat recovery step of the nanofiltration reverse osmosis process, the production water and brine are heat exchanged to reduce the temperature of the brine to 25-30°C; preferably, the production water and brine are heat exchanged using a heat exchanger; In the heat recovery step of the electrodialysis process, the production water raw water and the electrodialysis concentrate are used for heat exchange, and the electrodialysis concentrate is cooled by the production water raw water to 30-35°C; preferably, a heat exchanger is set on the electrodialysis concentrate side, and the production water raw water and the electrodialysis concentrate are exchanged with heat through the heat exchanger.

4. A new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to any one of claims 1 to 3, characterized in that: When recovering medium-grade heat, in the heat recovery step of the cooling section of the lithium carbonate process, the produced water from which low-grade heat has been recovered or / and the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process are indirectly exchanged with the high-temperature lithium carbonate to cool the lithium carbonate solid to ~60°C; preferably, the medium-grade heat is recovered by indirect heat exchange in a lithium carbonate solid conveying screw, a cooling drum, or a powder flow cooler; In the heat recovery step of the air compression process, the compression heat of the air compressor is removed using produced water with recovered low-grade heat and / or reverse osmosis fresh water generated in the nanofiltration reverse osmosis process, and the compressed air is cooled to 30-50°C, thereby recovering medium-grade heat. In the heat recovery step of the concentration process, the produced water from which low-grade heat has been recovered and / or the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process are used to cool the concentrated evaporation tail gas, the steam compressor lubricating oil system, and the vacuum pump liquid ring through a heat exchanger, thereby recovering the medium-grade heat. The concentrated evaporation tail gas is cooled to 30-40°C, and the vacuum pump liquid ring is cooled to 30-50°C. Preferably, the concentrated evaporation tail gas and the vacuum pump liquid ring are cooled through a plate heat exchanger. In the heat recovery step of the mother liquor recovery, the produced water from which low-grade heat has been recovered and / or the reverse osmosis fresh water produced in the nanofiltration reverse osmosis process are used to exchange heat with the high-temperature lithium precipitation mother liquor through a heat exchanger, and the lithium precipitation mother liquor is cooled to 35-40°C to recover the medium-grade heat; preferably, the heat is exchanged with the high-temperature lithium precipitation mother liquor through a plate heat exchanger.

5. The new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to claim 1, characterized in that: The temperature of the produced water from which low-grade heat is recovered is 25-32°C.

6. The new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to claim 1, characterized in that: The temperature of the produced water after recovering the medium-grade heat is 30-40°C.

7. The new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to claim 1, characterized in that: The thermal desorption temperature is 30 to 42°C, preferably 30 to 38°C.

8. The new process for extracting lithium from salt lakes with efficient and balanced energy utilization according to claim 1, characterized in that: The temperature of the reverse osmosis fresh water produced by the nanofiltration reverse osmosis process is 25-35°C.

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