阅读说明：本技术 一种从氢氧化锂母液中分离钠钾的方法 (Method for separating sodium and potassium from lithium hydroxide mother liquor ) 是由 沙亚利 李庆玲 李南平 于 2020-12-28 设计创作，主要内容包括：本发明公开一种从氢氧化锂母液中分离钠钾的方法,首先将一定量硫酸锂加入氢氧化锂母液中,得到溶液A；接着控制冷冻速率,将溶液A冷冻至一定温度,析出固体,离心分离后得到溶液B和固体A,固体A搅洗后烘干,测试其化学成分；然后将溶液B继续冷冻至一定温度,析出固体,离心分离后得到溶液C和芒硝；最后测试溶液C中钾含量,达标后返回氢氧化锂生产体系,循环利用。用此方法分离钠钾制备硫酸钾,工艺简单易操作,反应过程绿色安全无污染,降低原有生产系统循环体量,降低生产成本,可做到生产零排放,具有较好的经济效应。(The invention discloses a method for separating sodium and potassium from lithium hydroxide mother liquor, which comprises the steps of firstly, adding a certain amount of lithium sulfate into the lithium hydroxide mother liquor to obtain a solution A; then controlling the freezing rate, freezing the solution A to a certain temperature, separating out solids, performing centrifugal separation to obtain a solution B and a solid A, stirring and drying the solid A, and testing chemical components of the solid A; then continuously freezing the solution B to a certain temperature, separating out solids, and performing centrifugal separation to obtain a solution C and mirabilite; and finally, testing the potassium content in the solution C, returning to a lithium hydroxide production system after reaching the standard, and recycling. The method for preparing potassium sulfate by separating sodium and potassium has the advantages of simple and easy operation process, green, safe and pollution-free reaction process, reduction of the circulating amount of the original production system, reduction of the production cost, zero emission of production and better economic effect.)

1. A method for separating sodium and potassium from lithium hydroxide mother liquor is characterized by comprising the following steps:

step 1: adding a certain amount of lithium sulfate into lithium hydroxide mother liquor to obtain a solution A, and placing the solution A into a dry dust-free beaker;

step 2: controlling the freezing rate, freezing the solution A to a certain temperature, separating out solids, performing centrifugal separation to obtain a solution B and a solid A, stirring and drying the solid A, and testing chemical components of the solid A;

and step 3: continuously freezing the solution B to a certain temperature, and separating by using a crystallization separation device to obtain a solution C and mirabilite;

and 4, step 4: and (4) testing the potassium content of the solution C, returning the solution C to a lithium hydroxide production system for recycling after meeting the standard, and returning the solution C to the solution B for re-separation if not meeting the standard.

2. A process according to claim 1, wherein said catalyst is selected from the group consisting of lithium hydroxideThe method for separating sodium and potassium from the mother liquor is characterized in that the lithium hydroxide mother liquor in the step 1 is Li₂Adding lithium hydroxide solution with O content of 50-70 g/L, K being higher than 25 g/L, Na being higher than 60 g/L into the solution, wherein the amount of added lithium sulfate is the amount of Na in the solution⁺: SO₄ ^2-The molar ratio is 2-2.2: 1 meter.

3. The method for separating sodium and potassium from lithium hydroxide mother liquor as claimed in claim 1, wherein the solution A is frozen to 5-15 ℃ at a freezing rate of 3-8 min/° C in step 2.

4. The method for separating sodium and potassium from lithium hydroxide mother liquor as claimed in claim 1, wherein the solution B is frozen to-10 ℃ to-5 ℃ in the step 3.

5. The method for separating sodium and potassium from lithium hydroxide mother liquor as claimed in claim 1, wherein the potassium concentration in the filtrate C in the step 4 is lower than 15 g/L, and the standard is determined to be met.

Technical Field

The invention belongs to the field of mother liquor recovery and treatment, and particularly relates to a method for separating sodium and potassium from lithium hydroxide mother liquor.

Background

With the vigorous development of the lithium ion battery and other new energy material industries, lithium salt products such as lithium carbonate, lithium hydroxide and the like have wider prospects, but in the process of producing battery-grade lithium hydroxide according to the traditional method, because the potassium content in raw material ores is high, potassium and sodium can be greatly enriched in the system circulation process, if the conventional means is adopted to directly and uniformly recover sodium and potassium so as to simply treat the sodium and potassium as byproducts, the value waste of a large amount of potassium can be caused.

Potassium sulfate is mainly used as potash fertilizer in agriculture, and is mainly used in the preparation fields of glass, dye, spice, medicine and the like in industry. At present, potassium sulfate is mainly prepared by taking sulfate type potassium salt ores and potassium salt lake brine as raw materials, the earth resources are always limited, a method for separating sodium and potassium from lithium hydroxide mother liquor is designed for realizing the green sustainable development concept of enterprises, and a high-purity potassium sulfate product is extracted extremely necessarily, so that the circulating amount of an original production system can be reduced, the production cost is reduced, zero emission of production is realized, and meanwhile, an obvious economic effect can be generated.

Disclosure of Invention

The invention aims to provide a method for separating sodium and potassium from lithium hydroxide mother liquor, which has the advantages of simple process, easy operation, green, safe and pollution-free reaction process, production emission reduction, reasonable resource utilization, cost saving and enterprise economic benefit improvement.

The invention is realized by the following steps: a method for separating sodium and potassium from lithium hydroxide mother liquor specifically comprises the following steps:

step 1: adding a certain amount of lithium sulfate into lithium hydroxide mother liquor to obtain a solution A, and placing the solution A into a dry dust-free beaker;

step 2: controlling the freezing rate, freezing the solution A to a certain temperature, separating out solids, performing centrifugal separation to obtain a solution B and a solid A, stirring and drying the solid A, and testing chemical components of the solid A;

and step 3: continuously freezing the solution B to a certain temperature, and separating by using a crystallization separation device to obtain a solution C and mirabilite;

and 4, step 4: and (4) testing the potassium content of the solution C, returning to a lithium hydroxide production system for recycling after meeting the standard, and returning to the solution B for re-separation if not meeting the standard.

Further, the lithium hydroxide mother liquor in the step 1 is Li₂Lithium hydroxide solution with O content of 50-70 g/L, K higher than 25 g/L, Na higher than 60 g/LAdding lithium sulfate according to the amount of Na in the solution⁺: SO₄ ^2-The molar ratio is 2-2.2: 1 meter.

Further, solution A in step 2 was frozen to 5-15 ℃ at a freezing rate of 3-8 min/deg.C.

Further, in step 3, solution B was frozen to-10 ℃ to-5 ℃.

Further, in step 4, the potassium concentration in the filtrate C is lower than 15 g/L, which is considered to be in accordance with the standard.

Has the advantages that:

the invention discloses a method for separating sodium and potassium from lithium hydroxide mother liquor, which has simple and easy operation, adopts twice freezing process to efficiently recover sodium and potassium in the lithium hydroxide mother liquor, reduces the waste of resources, can also reduce the circulating amount of an original production system, is green, safe and pollution-free in the whole reaction process, effectively reduces the production cost, and effectively ensures the economic benefits of enterprises.

Drawings

FIG. 1 is a statistical chart of the results of chemical composition tests of solid A and liquid C obtained in examples 1 to 5;

FIG. 2 is a schematic view of a crystal separation apparatus;

FIG. 3 is a schematic bottom view of the cage;

FIG. 4 is a schematic top view of the annular platen;

FIG. 5 is an enlarged view of portion A of FIG. 2;

wherein, 1-freezing crystallization component, 2-crystal growing component and 3-fine crystal settling component;

11-a circulating pump, 12-a refrigerating device, 13-a freezing crystallizer, 14-a discharge pump, 15-a feeding pipe, 16-a circulating liquid outlet and 17-a freezing discharge pipe;

21-thickener, 22-mirabilite centrifuge, 23-hydrocyclone, 24-separated liquid outlet and 25-crystal outlet;

31-a settler, 32-a back flushing pump, 33-a clear liquid outlet, 34-a sedimentation liquid outlet, 35-a stirring device, 36-an isolation hood, 37-a connecting disc and 38-a hydraulic device;

351-motor, 352-stirring shaft, 353-stirring rod, 354-cross rod and 355-sliding ball bearing;

381-annular pressure plate, 382-fixed rod, 383-telescopic segment, 384-spring, 385-annular sliding groove and 386-wall brush.

Detailed Description

The following detailed description of the preferred embodiments of the present invention is provided to enable those skilled in the art to more readily understand the advantages and features of the present invention, and to clearly and unequivocally define the scope of the present invention.

Example 1

Adding 110 g of lithium sulfate solid into 2000 mL of lithium hydroxide mother liquor, stirring until the lithium sulfate solid is completely dissolved, performing suction filtration, placing the obtained product in a dry dust-free beaker, controlling the freezing rate to be 5 min/DEG C, freezing to be 5 ℃, performing centrifugal separation to obtain 20.37 g of solid, and mixing the solid with a mixed solution of 1: and (3) stirring 1 amount of pure water, drying at 100 ℃ for testing, continuously freezing the liquid to-5 ℃, separating by using a crystallization separation device, collecting the solid, and returning the liquid to the production system when the liquid meets the requirement after testing the potassium content.

Example 2

Adding 115 g of lithium sulfate solid into 2000 mL of lithium hydroxide mother liquor, stirring until the lithium sulfate solid is completely dissolved, performing suction filtration, placing the obtained product in a dry dust-free beaker, controlling the freezing rate to be 5 min/DEG C, freezing to be 10 ℃, performing centrifugal separation to obtain 19.03 g of solid, and mixing the solid with a mixed solution of 1: and (3) stirring 1 amount of pure water, drying at 100 ℃ for testing, continuously freezing the liquid to-8 ℃, separating by using a crystallization separation device, collecting the solid, and returning the liquid to the production system when the liquid meets the requirement after testing the potassium content.

Example 3

Adding 112 g of lithium sulfate solid into 2000 mL of lithium hydroxide mother liquor, stirring until the lithium sulfate solid is completely dissolved, performing suction filtration, placing the obtained product in a dry dust-free beaker, controlling the freezing rate to be 8 min/DEG C, freezing to be 5 ℃, performing centrifugal separation to obtain 22.61 g of solid, and mixing the solid with a mixed solution of 1: and (3) stirring 1 amount of pure water, drying at 100 ℃ for testing, continuously freezing the liquid to-8 ℃, separating by using a crystallization separation device, collecting the solid, and returning the liquid to the production system when the liquid meets the requirement after testing the potassium content.

Example 4

Adding 120 g of lithium sulfate solid into 2000 mL of lithium hydroxide mother liquor, stirring until the lithium sulfate solid is completely dissolved, performing suction filtration, placing the obtained product in a dry dust-free beaker, controlling the freezing speed to be 3 min/DEG C, freezing to be 10 ℃, performing centrifugal separation to obtain 20.12 g of solid, and mixing the solid with a solvent of 1: and (3) stirring 1 amount of pure water, drying at 100 ℃ for testing, continuously freezing the liquid to-5 ℃, separating by using a crystallization separation device, collecting the solid, and returning the liquid to the production system when the liquid meets the requirement after testing the potassium content.

Example 5

Adding 115 g of lithium sulfate solid into 2000 mL of lithium hydroxide mother liquor, stirring until the lithium sulfate solid is completely dissolved, performing suction filtration, placing the obtained product in a dry dust-free beaker, controlling the freezing rate to be 6 min/DEG C, freezing to be 8 ℃, performing centrifugal separation to obtain 18.75 g of solid, and mixing the solid with a mixed solution of 1: and (3) stirring 1 amount of pure water, drying at 100 ℃ for testing, continuously freezing the liquid to-8 ℃, separating by using a crystallization separation device, collecting the solid, and returning the liquid to the production system when the liquid meets the requirement after testing the potassium content.

FIG. 1 is a statistical chart of the chemical composition test results of the solid A and the liquid C obtained in examples 1 to 5, and it can be known from the statistical chart that most of sodium and potassium in the lithium hydroxide mother liquor are separated out respectively and can be used for recycling of other purposes, so that the waste of materials is reduced, and the method can reduce the circulating pressure of a production system and has economic benefits.

The crystal separation device used in each embodiment comprises a freezing crystallization component 1, a crystal growing component 2 and a fine crystal settling component 3;

the freezing and crystallizing component 1 comprises a circulating pump 11, a refrigerating device 12, a freezing crystallizer 13 and a discharge pump 14; the crystal growing assembly 2 comprises a thickener 21, a mirabilite centrifugal machine 22 and a hydrocyclone 23; the fine crystal settling assembly 3 comprises a settler 31 and a recoil pump 32;

the freezing crystallizer 13 is provided with an inner cavity, and a feeding pipe 15 communicated with the inner cavity is arranged on the freezing crystallizer 13,

A circulating liquid outlet 16 and a freezing discharge pipe 17; the circulating liquid outlet 16 is communicated with a refrigerating device 12 through a circulating pump 11, and the refrigerating device 12 is communicated with a freezing crystallizer 13; the freezing discharge pipe 17 is communicated with the discharge pump 14;

the discharge hole of the discharge pump 14 is communicated with a hydrocyclone 23, and the hydrocyclone 23 is provided with a separation liquid outlet 24 and a crystal outlet 25; the separation liquid outlet 24 is communicated with the inner cavity of the freezing crystallizer 13, and the crystal outlet 25 is communicated with the thickener 21;

the liquid outlet of the thickener 21 is communicated with the feed inlet of the mirabilite centrifugal machine 22, and the outlet of the mirabilite centrifugal machine 22 is communicated with the settler 31; the upper part of the settler 31 is provided with a clear liquid outlet 33, the bottom of the settler is provided with a settling liquid outlet 34, the settling liquid outlet 34 is provided with a back flushing pump 32, and the back flushing pump 32 is communicated with the feeding pipe 15.

When the device is used, firstly, the solution B is conveyed into the freezing crystallizer 13 through the feeding pipe 15, the circulating pump 11 is started after the slurry submerges the circulating liquid outlet 16, the circulating pump 11 sucks the slurry out of the circulating liquid outlet 16, the slurry is conveyed to the refrigerating device 12 for cooling, the cooled slurry is conveyed into the freezing crystallizer 13 again, the circulation is repeated in such a way until the temperature of the slurry is frozen to-10-5 ℃, a large amount of mirabilite crystals are separated out from the cooled slurry in the freezing crystallizer 13 due to the temperature reduction, and the mirabilite crystals are settled to the bottom of the freezing crystallizer 13 under the action of self gravity.

Then, the freezing feed liquid containing mirabilite crystals is sent into a hydrocyclone 23 through a discharge pump 14 through a freezing discharge pipe 17, the separated clear liquid returns to the freezing crystallizer 13 through a separation liquid outlet 24 (the clear liquid contains a small amount of fine crystals), and the slurry containing a large amount of coarse particles of mirabilite enters a thickener 21 through a crystal outlet 25.

In thickener 21, the slurry containing a large amount of coarse mirabilite is crystallized and settled, then the crystallized slurry is sent to mirabilite centrifuge 26 for separation, the separated liquid (containing 15% of fine crystals) is sent to settler 31, and the solid mirabilite is separated.

The liquid separated by centrifugation is conveyed to a settler 31, fine mirabilite crystals are slowly settled, the supernatant overflows to a clear liquid storage tank from a clear liquid outlet 33, the supernatant is returned to the production system according with the requirement after potassium content is tested, and the mirabilite crystals at the lower layer are returned to a freezing crystallizer 13 from a settling liquid outlet 34 to be used as seed crystals, so that the crystal granularity is increased.

In order to avoid the mirabilite crystals from being attached to the inner wall of the settler 31 and simultaneously avoid the fixed accumulation of the mirabilite crystals at corners, a stirring device 35 is arranged in the settler 31, the stirring device 35 comprises a motor 351, a stirring shaft 352 and stirring rods 353, the motor 351 is fixed at the top of the settler 31 through a support, one end of the stirring shaft 352 is connected with the motor 351, the other end of the stirring shaft 352 extends into the lower end of the settler 31, a cross rod 354 is arranged at the bottom of the stirring shaft 352, and a plurality of stirring rods 353 are uniformly distributed above the cross;

in order to realize stirring crystallization at normal stirring speed and keep the liquid flowing speed in the settler 31 at a lower level while stirring and increase the precipitation effect, a plurality of annular isolation hoods 36 are arranged in the settler 31 to divide the interior of the settler 31 into a plurality of annular spaces, the top end of each isolation hood 36 is fixedly connected with a connecting disc 37, the top of each connecting disc 37 is fixedly connected with the top of the settler 31, stirring rods 353 are uniformly arranged in the spaces enclosed by the correspondingly arranged isolation hoods 36, and the liquid is divided between the adjacent isolation hoods 36 by utilizing the mode so as to reduce the flowing between the liquid, thereby reducing the liquid flowing interference to the maximum degree and ensuring the fine-grain precipitation effect.

In order to prevent the liquid level from floating and influencing the fine grain precipitation effect, a hydraulic device 38 is arranged in the settler 31 and below the connecting disc 37, the hydraulic device 38 is composed of a plurality of annular pressing plates 381 which are distributed in a flush mode, the annular pressing plates 381 which are located between adjacent isolation covers 36 are embedded between the adjacent isolation covers 36 in a matching mode so as to move longitudinally along the surfaces of the isolation covers 36, an annular pressing plate 381 is also arranged between the isolation covers 36 and the inner wall of the settler 31, the inner side wall of the annular pressing plate is in contact with the outer wall of the outermost isolation cover 36, the tops of the annular pressing plates 381 are connected into a whole through a fixing rod 382, a telescopic section 383 is arranged at the top of the fixing rod 382, and a spring 384 is arranged in the telescopic.

In order to prevent the annular pressure plate 381 from interfering with the stirring rod 353 when the annular pressure plate 381 descends, the stirring rod 353 is a longitudinal telescopic rod, a sliding ball 355 is provided on the top of the stirring rod 353, and an annular sliding groove 385 is provided on the bottom of the annular pressure plate 381 at a position corresponding to the sliding ball 355.

In the specific using process, the liquid centrifugally separated by the mirabilite centrifugal machine 26 enters the settler 31 from the bottom of the settler 31, after the liquid is filled in the space between the isolation covers 36, the annular pressure plate 381 gradually and stably floats upwards under the action of the liquid at the bottom, so that the spring 384 in the telescopic section 383 is stressed and compressed, then the motor 351 is started to drive the stirring rod 353 to rotate, the sliding balls 355 at the top of the stirring rod 353 make a circular motion along the annular sliding groove 385, when fine crystal sedimentation is finished, clear liquid is led out from a clear liquid outlet 33 at the upper end, mirabilite crystals at the lower layer flow out from a sedimentation liquid outlet 34, during the process of flowing out the clear liquid, the total liquid level is lowered, the annular pressure plate 381 is subjected to the buoyancy of the bottom liquid to be reduced, under the action of the elastic restoring force of the spring, the annular pressure plate 381 descends synchronously along with the liquid level, the annular pressure plate 381 is always pressed above the liquid level, the liquid level is stable in sinking, and the fine grains can not float greatly in the process of leading out the liquid.

The outer side surface of the annular pressure plate 381 between the isolation cover 36 and the inner wall of the settler 31 is provided with a wall brush 386, which can not only not influence the outflow of clear liquid, but also scrape a small amount of crystals adhered to the wall of the settler 31 in the process of descending the annular pressure plate 381.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.