阅读说明：本技术 一种部分电离含钠锂卤水的钠锂分离的方法 (Method for separating sodium and lithium by partially ionizing sodium-lithium-containing brine ) 是由 张勇 桑子容 韩培林 罗喆 陈喆 于 2020-12-11 设计创作，主要内容包括：本发明公开了一种部分电离含钠锂卤水的钠锂分离的方法,包括以下步骤：S1：将含有NaCl和LiCl体系的盐湖卤水进行部分电解,得到LiCl和NaOH溶液体系；S2：向LiCl和NaOH溶液体系中加入H_2SO_4,得到LiCl和Na_2SO_4溶液体系；S3：将LiCl和Na_2SO_4溶液进行蒸发处理,使Na_2SO_4呈饱和状态,得到待冷冻溶液；S4：向待冷冻溶液中加入冷冻辅助剂；S5：将具有冷冻辅助剂的待冷冻液进行冷冻结晶处理,并离心分离得到LiCl锂液和Na_2SO_4·10H_2O晶体。本申请通过将原溶液中的氯化物体系转化为硫酸根体系,充分利用了硫酸钠的冷冻结晶技术手段,实现锂钠的高效分离,克服了领域中体系转化障碍。(The invention discloses a method for separating sodium and lithium by partially ionizing sodium-lithium-containing brine, which comprises the following steps: s1: carrying out partial electrolysis on salt lake brine containing a NaCl and LiCl system to obtain a LiCl and NaOH solution system; s2: adding H into LiCl and NaOH solution system 2 SO 4 Obtaining LiCl and Na 2 SO 4 A solution system; s3: mixing LiCl and Na 2 SO 4 Evaporating the solution to obtain Na 2 SO 4 The solution is in a saturated state to obtain a solution to be frozen; s4: adding a freezing auxiliary agent into the solution to be frozen; s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent, and centrifugally separating to obtain LiCl lithium liquid and Na 2 SO 4 •10H 2 And (4) O crystals. According to the method, a chloride system in an original solution is converted into a sulfate system, the freezing crystallization technical means of sodium sulfate is fully utilized, the high-efficiency separation of lithium and sodium is realized, and the defects of the prior art that the sodium sulfate is not dissolved in the original solution are overcomeSystem transformation disorder.)

1. A method for separating sodium and lithium by partially ionizing sodium-lithium-containing brine is characterized by comprising the following steps of:

s1: carrying out partial electrolysis on salt lake brine containing a NaCl and LiCl system to obtain a LiCl and NaOH solution system;

s2: adding H into LiCl and NaOH solution system₂SO₄Obtaining LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solution to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

2. Such as rightThe process for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine of claim 1, wherein: NaCl and LiCl solution System in S1 3>n_Li+/n_Na+>20。

3. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: s2 with H₂SO₄With Na⁺In a molar ratio of 1: 4.

4. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: the evaporation temperature in S3 is 32.4-100 ℃.

5. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: the freezing auxiliary agent in S4 is one or more of ethanol, ethylamine, acetonitrile, isopropanol, propanol and butanol; the addition amount of the freezing auxiliary agent is 2-55% of the mass of the salt lake brine.

6. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: the freezing temperature in S5 is-20 to 10 ℃.

7. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: na obtained in S5₂SO₄·10H₂The O crystal can also be used in S3 to make Na₂SO₄Is in a saturated state.

8. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: the LiCl lithium solution obtained in S5 can also be recycled to salt lake brine in S1 for cyclic extraction and separation.

9. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: the solution to be frozen can also be added with an auxiliary agent, and the addition amount is 0.1-1% of the mass of the salt lake brine; the auxiliary agent is one or more of fatty alcohol polyoxyethylene ether sodium carboxylate, octadecyl trimethyl ammonium chloride and polyacrylamide.

10. The process of claim 1 for the separation of sodium from lithium in a partially ionized sodium-lithium containing brine, wherein: LiCl and NaOH solution system after S1 ionization is not less than 0.98 and not more than nOH^-/nNa⁺≤1.1。

Technical Field

The invention belongs to the technical field of lithium extraction in salt lakes, and particularly relates to a sodium-lithium separation method for partially ionizing sodium-lithium-containing brine.

Background

China is a large lithium resource country and has abundant bittern resources. The lithium extraction from the salt lake generally needs to take old brine left after sodium and potassium ions are filtered as a raw material, and the old brine is subjected to secondary lithium enrichment and then subjected to evaporation, magnesium removal and concentration to extract lithium ions to prepare lithium carbonate. However, since lithium and sodium belong to the same group of elements, their ion masses are light and their chemical properties are very similar, and it is difficult to completely separate them using conventional methods.

At present, the effective separation of sodium is carried out by utilizing the freezing crystallization principle of sodium sulfate in the technical field of caustic soda and the technical field of lithium extraction from ores, sodium ions and most of water are brought out in the form of crystal water of sodium sulfate decahydrate due to certain particularity of the solubility of sodium sulfate, and then the separation of sodium and the concentration of a solution are realized.

The original systems in the technical field all contain sulfate radicals, so that sodium sulfate decahydrate crystals can be formed under the freezing condition, for example, lithium sulfate and sodium hydroxide in the system for extracting lithium from ore form sodium sulfate decahydrate crystals and lithium hydroxide liquid under the freezing condition, and the separation of lithium and sodium is realized.

However, in the technical field of lithium extraction in salt lakes, lithium and sodium in a salt lake brine system mainly exist in the forms of lithium chloride and sodium chloride, cannot be directly separated by the principle of sodium sulfate crystallization, and Cl is in the chemical field^-System and SO₄ ^2-The conversion of the system is relatively complex, so that the lithium extraction in the salt lake is generally separated in a direct evaporation crystallization and simple electrolysis mode at present. LiCl and NaCl in sodium-lithium-containing brine are electrolyzed by an electrolysis method to generate a solution containing LiOH and NaOH, and the solution is evaporated and crystallized to obtain LiOH crystals, but the LiOH crystals obtained by the method contain more NaOH impurities, are difficult to wash and have large lithium loss; meanwhile, the direct evaporation crystallization also has the technical problems of unclear separation of lithium and sodium, serious washover and large evaporation capacity.

Disclosure of Invention

The invention aims to provide a method for separating sodium and lithium by partially ionizing sodium-lithium-containing brine, which realizes the crystallization separation of sodium sulfate by converting a chloride system in a raw solution into a sulfate system.

The invention discloses a method for separating sodium and lithium by partially ionizing sodium-lithium-containing brine, which comprises the following steps:

s1: carrying out partial electrolysis on salt lake brine containing a NaCl and LiCl system to obtain a LiCl and NaOH solution system;

s2: adding H into LiCl and NaOH solution system₂SO₄Obtaining LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solution to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

Further, 3 in the NaCl and LiCl solution system in S1>n_Li+/n_Na+>20。

Further, H was added to S2₂SO₄With Na⁺In a molar ratio of 1: 4.

Further, the evaporation temperature in S3 is 32.4-100 ℃.

Further, the freezing adjuvant in S4 is one or more of ethanol, ethylamine, acetonitrile, isopropanol, propanol, and butanol.

Further, the freezing temperature in S5 is-20 to 10 ℃.

Further, Na obtained in S5₂SO₄·10H₂The O crystal can also be used in S3 to make Na₂SO₄Is in a saturated state.

Further, LiCl lithium solution obtained in S5 can be recycled to salt lake brine in S1 for cyclic extraction and separation. This can be improved even betterThe content of LiCl in the final lithium liquid further realizes the efficient separation of lithium and sodium, and n in the final lithium liquid is provided by the application_Li+/n_Na+>And 20, obtaining qualified lithium liquid.

Furthermore, the solution to be frozen can be added with an auxiliary agent, and the addition amount is 0.1-1% of the mass of the salt lake brine.

Further, the auxiliary agent is one or more of fatty alcohol polyoxyethylene ether sodium carboxylate, octadecyl trimethyl ammonium chloride and polyacrylamide. Because the crystal form of the sodium sulfate crystal formed under the system is fine, the crystal is easy to form and float, and the filtering separation is not easy, all the added auxiliary agents can better ensure the crystal formation of larger particles, the subsequent filtering is convenient, and the rapid and efficient separation is further realized.

The invention has the beneficial effects that:

(1) according to the method, a chloride system in an original solution is converted into a sulfate system, the freezing crystallization technical means of sodium sulfate is fully utilized, the high-efficiency separation of lithium and sodium is realized, and the system conversion obstacle in the field is overcome.

(2) The present invention forms Na by adding anhydrous sodium sulfate to sodium-lithium-containing brine and using a freeze crystallization₂SO₄·10H₂The O crystal takes out most of water in the solution in the form of crystal water, so that the sodium and lithium separation and concentration of the mixed solution are realized, the evaporation water amount in the lithium extraction process is greatly reduced, the lithium loss is low, the energy consumption is low, and the comprehensive cost in the lithium extraction process is obviously reduced.

(3) By adding the freezing auxiliary agent, the negative influence of the salt effect on the crystallization separation can be better avoided, and the crystallization effect of the sodium sulfate decahydrate is further improved, so that the high-degree sodium-lithium separation is effectively ensured.

(4) The crystallization auxiliary agent added in the invention can better ensure the formation of crystals of larger particles, is convenient for subsequent filtration and further realizes rapid and efficient separation.

Drawings

Figure 1 is a solubility curve for sodium sulfate.

Detailed Description

The invention will be further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, various changes or modifications of the present invention may be made by those skilled in the art, and equivalents may fall within the scope of the claims of the present application. The proportions in the examples of the invention are by weight.

Example 1

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 8.3) partial electrolysis to obtain LiCl and NaOH solution system, and ensuring that nOH is more than or equal to 0.98 in the system^-/nNa⁺≤1.1；

S2: adding H into LiOH and LiCl solution system₂SO₄Adding H₂SO₄With Na⁺In a molar ratio of 1:4 to obtain LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solution at 40 deg.C to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen; the freezing auxiliary agent is ethanol;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at-20 ℃, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

Example 2

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 6.5) partial electrolysis to obtain LiCl and NaOH solution system, and ensuring that nOH is more than or equal to 0.98 in the system^-/nNa⁺≤1.1；

S2: adding H into LiCl and NaOH solution system₂SO₄Adding H₂SO₄With Na⁺In a molar ratio of 1:4 to obtain LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solutionEvaporating at 80 deg.C to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen; the freezing auxiliary agent is isopropyl;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at-10 deg.C, and centrifuging to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

Example 3

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 8.8) partial electrolysis to obtain LiCl and NaOH solution system and ensure that nOH is more than or equal to 0.98 in the system^-/nNa⁺≤1.1；

S2: adding H into LiCl and NaOH solution system₂SO₄Adding H₂SO₄With Na⁺In a molar ratio of 1:4 to obtain LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solution at 100 deg.C to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen; the freezing auxiliary agent is ethylamine;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at 5 ℃, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

Example 4

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 3.8) partial electrolysis to obtain LiCl and NaOH solution system, and ensuring that nOH is more than or equal to 0.98 in the system^-/nNa⁺≤1.1；

S2: adding H into LiCl and NaOH solution system₂SO₄Adding H₂SO₄With Na⁺In a molar ratio of 1:4 to obtain LiCl and Na₂SO₄A solution system;

s3: mixing LiOH and Na₂SO₄Evaporating the solution at 100 deg.C, and adding Na obtained in S5 before evaporation₂SO₄·10H₂Crystal of O to Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen; the freezing auxiliary agent is ethanol;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at-20 ℃, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂O crystals; and recycling the obtained LiCl lithium solution into salt lake brine in S1 for repeated circulating extraction and separation.

Example 5

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 6.8) partial electrolysis to obtain LiCl and NaOH solution system, and ensuring that nOH is more than or equal to 0.98 in the system^-/nNa⁺≤1.1；

S2: adding H2SO4 into a LiCl and NaOH solution system, wherein the molar ratio of the added H2SO4 to Na + is 1:4, SO as to obtain a LiCl and Na2SO4 solution system;

s3: evaporating LiCl and Na2SO4 solution at 100 deg.C to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen; the freezing auxiliary agent is ethanol propanol;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at-20 ℃, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals. .

Example 6

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 8.5) partial electrolysis to obtain LiCl and NaOH solution system, and ensuring that nOH is more than or equal to 0.98 in the system^-/nNa⁺≤1.1；

S2: adding H into LiCl and NaOH solution system₂SO₄Adding H₂SO₄With Na⁺In a molar ratio of 1:4 to obtain LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solution at 100 deg.C to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: adding a freezing auxiliary agent into the solution to be frozen; the freezing auxiliary agent is ethanol and acetonitrile;

s5: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at-20 ℃, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

Comparative example 1

S1: adding salt lake brine (n) containing NaCl and LiCl system_Li+/n_Na+= 10.2) partial electrolysis to obtain a LiCl and NaOH solution system;

s2: adding H into LiCl and NaOH solution system₂SO₄Adding H₂SO₄With Na⁺In a molar ratio of 1:4 to obtain LiCl and Na₂SO₄A solution system;

s3: mixing LiCl and Na₂SO₄Evaporating the solution at 100 deg.C to obtain Na₂SO₄The solution is in a saturated state to obtain a solution to be frozen;

s4: freezing and crystallizing the liquid to be frozen with the freezing auxiliary agent at-20 ℃, and centrifugally separating to obtain LiCl lithium liquid and Na₂SO₄·10H₂And (4) O crystals.

Sodium ion measurement is carried out on the separated lithium liquid to obtain n_Li+/n_Na+23.4, the sodium ions are reduced from 31.4g originally to 14.12g currently; conventional evaporative crystallization separation of n_Li+/n_Na+Between about 6 and about 12; the lithium liquid was subjected to impurity testing, and the results are shown in the following table

Evaluation: according to the measurement result and the impurity content of the separated lithium liquid, the method has a strong effect on the separation of lithium and sodium in the brine, and the efficiency is higher than that of the traditional method. The energy consumption is low, the subsequent treatment is not needed, and the next process can be directly carried out. And the subsequent byproduct sodium sulfate crystal can be used as a raw material in other industries.

In conclusion, the method disclosed by the invention has the advantages that the method has a high-efficiency separation method, sodium and lithium ions in brine can be effectively separated, the separation efficiency is superior to that of the traditional industrial method, the operation process is simpler, the energy consumption is lower, and a novel innovative and feasible scheme is provided for industrial production.

The embodiments of the present invention have been described above by way of example, but the description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. All equivalent changes and modifications within the scope of the application of the present invention shall fall within the scope of the patent of the present invention.