WO2023087799A1 - Method for removing calcium-enriched lithium from salt lake brine with high calcium-lithium ratio - Google Patents

Abstract

A method for removing calcium-enriched lithium from salt lake brine with a high calcium-lithium ratio. The method comprises the following steps: (1) naturally evaporating the original lithium-containing brine of a calcium chloride type salt lake to precipitate a mixed salt of potassium and sodium, and then acidifying the brine to remove boron; and (2) subjecting the brine treated in step (1) to natural evaporation-freezing calcium precipitation operation at least once, wherein the freezing calcium precipitation operation involves cooling the brine to precipitate a calcium chloride crystal, and then performing solid-liquid separation on same to obtain a lithium-enriched concentrated brine. The method has the characteristics of a simple process, simple operation, high calcium-lithium separation efficiency and low consumption of energy, water and chemical reagents. The method is particularly suitable for extracting lithium from salt lake brine with high calcium-lithium ratio in areas with poor infrastructure and insufficient energy supply, and has a practical significance on the utilization of lithium resources in salt lakes.

Description

A method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine technical field

The invention belongs to the technical field of extracting lithium from salt lakes, in particular to a method for removing calcium and enriching lithium from salt lake brine with a high calcium-to-lithium ratio.

Background technique

Lithium and lithium compounds such as lithium chloride, lithium carbonate, lithium hydroxide and organic lithium compounds are widely used in high-energy batteries, aerospace, nuclear power generation and other fields, and are of great significance to the development of my country's national economy. Lithium is the main cathode material for high-energy batteries, and has an important strategic position in the development of energy storage materials and clean nuclear energy. With the rapid development of science and technology and the sharp increase in energy demand, energy is facing great challenges. Lithium batteries have gradually become the mainstay of the battery industry.

Salt lake lithium resources account for more than 69% of the world's industrial reserves of lithium resources. Extracting lithium from salt lake brine has become the top priority of my country's competition for energy strategic heights and is a major national strategic demand. The world's salt lake lithium resources are mainly distributed in South America, North America and Asia; the salt lake area is often sparsely populated, the infrastructure is not perfect, and the energy supply is insufficient, which has brought serious constraints to the development and utilization of these lithium resources. The methods for extracting lithium from brine mainly include evaporative crystallization, precipitation, extraction, adsorption, calcination, and membrane separation.

Among them, the evaporation crystallization method and precipitation method are mainly aimed at extracting lithium from salt lake brine with low magnesium-lithium ratio and calcium-lithium ratio; although extraction, adsorption, calcination and membrane separation methods can be applied to high magnesium-lithium ratio and high calcium-lithium ratio Lithium extraction from salt lake brine has certain problems. For example, in the extraction method, it is necessary to add high-concentration hydrochloric acid for back-extraction equipment corrosion is serious, and the organic solvent is easy to enter the brine after extraction, causing great pollution to the brine of the salt lake; the industrial application of the aluminum-based adsorption method in the adsorption method is relatively good, but There are also problems of high investment, water consumption, and power consumption; in the manganese-based and titanium-based adsorption methods, the acid and alkali consumption is large, and there are also problems such as adsorbent dissolution loss and high energy consumption; the calcination method produces a lot of by-products The hydrochloric acid is seriously corrosive to the equipment, and the process needs to evaporate a large amount of water, and the energy consumption is large; the electrodialysis method can only separate +1 and +2 valent ions, and in the presence of other +1 valent impurity ions (such as K+), The separation efficiency is low, and the service life of the filter membrane is short. Therefore, it is particularly important to seek a simple, efficient, energy-saving, and environmentally friendly technology for extracting lithium from salt lake brine with a high calcium-lithium ratio.

Contents of the invention

The present invention aims to solve at least one of the technical problems existing in the prior art. For this reason, the present invention proposes a method for removing calcium and enriching lithium from salt lake brine with a high calcium-lithium ratio. The method has the characteristics of simple process, easy operation, high separation efficiency of calcium and lithium, and low consumption of energy, water and chemical reagents , especially suitable for extracting lithium from salt lake brine with a high calcium-lithium ratio in areas with poor infrastructure and insufficient energy supply, which has practical significance for the utilization of lithium resources in salt lakes.

Above-mentioned technical purpose of the present invention is achieved through the following technical solutions:

A method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine, comprising the following steps:

(1) Naturally evaporate the lithium-containing raw brine of the calcium chloride type salt lake to precipitate potassium and sodium mixed salts, and then acidify the brine to remove boron;

(2) The brine treated in step (1) is subjected to at least one natural evaporation-freezing calcium precipitation operation, wherein the freezing calcium precipitation operation is to lower the temperature of the brine to precipitate calcium chloride crystals, and then perform solid-liquid separation to obtain Lithium-enriched concentrated brine.

Preferably, in step (1), the Ca/Li mass ratio in the lithium-containing raw brine of the calcium chloride-type salt lake is above 10.

Further preferably, in step (1), the Ca/Li mass ratio in the lithium-containing original brine of the calcium chloride-type salt lake is above 20.

Preferably, in step (1), when the calcium in the brine is saturated and calcium chloride crystals are about to be precipitated, the brine is acidified to remove boron.

Preferably, the pH of the brine after acidification in step (1) is 0.5-3.

Further preferably, the pH of the brine after acidification in step (1) is 0.5-2.

Preferably, in step (2), when the brine is naturally evaporated until the calcium content is above 140g/L, it is then subjected to freezing and calcium precipitation operation.

Further preferably, in step (2), when the brine is naturally evaporated until the calcium content is above 160g/L, it is then subjected to freezing and calcium precipitation operation.

Preferably, in step (2), the temperature of the brine is lowered to below 15°C by means of a freeze crystallization device.

Further preferably, in step (2), the temperature of the brine is lowered to below 10° C. by means of a freeze crystallization device.

Further preferably, in step (2), the temperature of the brine is lowered to below 5° C. by means of a freeze crystallization device.

Preferably, the freeze crystallization device in step (2) is a cooling crystallizer with a cooling jacket, and a cooling medium is passed through the cooling jacket.

Preferably, the temperature of the brine in step (2) is lowered by using fresh water and/or raw brine from a salt lake.

Preferably, in step (2), solid-liquid separation is carried out when the mass concentration of calcium chloride crystals in the cooling crystallizer is 20-70%.

Further preferably, in step (2), solid-liquid separation is carried out when the mass concentration of calcium chloride crystals in the cooling crystallizer is 25-65%.

Preferably, at least three natural evaporation-freeze calcium precipitation operations are carried out in step (2).

Preferably, the mass ratio of Ca/Li in the concentrated lithium-enriched brine obtained in step (2) is below 10.

Further preferably, the mass ratio of Ca/Li in the concentrated lithium-enriched brine obtained in step (2) is below 5.

The beneficial effects of the present invention are:

(1) The present invention utilizes the principle that the solubility of calcium chloride drops sharply at low temperatures, and realizes the separation of calcium and lithium from salt lake lithium-containing brine with a high calcium-lithium ratio by naturally evaporating and concentrating salt lake brine, cooling and crystallizing calcium, and obtaining Concentrated brine with low calcium-lithium ratio. This process takes advantage of the unique climate environment of the lake area. The process is simple and efficient, energy-saving and environmentally friendly, and low in cost. It effectively solves the technical problem of calcium-lithium separation, and is especially suitable for salt lake brine with a high calcium-lithium ratio in areas with poor infrastructure and insufficient energy supply. Lithium extraction;

(2) Compared with using the ambient temperature difference between day and night in the salt lake area to precipitate calcium chloride crystals, on the one hand, calcium-saturated brine has a good heat preservation effect after heating up during the day, and the temperature change from brine temperature to night is small, and the freezing effect is very poor. It is only suitable for freezing in winter; on the other hand, due to the small amount of evaporation in winter, it seriously limits the improvement of production efficiency. Therefore, the present invention lowers the temperature of the brine through a cooling crystallizer with a cooling jacket so as to achieve the purpose of multiple precipitation of calcium chloride crystals, and the production efficiency is significantly improved.

Description of drawings

Fig. 1 is a flowchart of the present invention.

Detailed ways

The present invention will be further described in detail below by taking the extraction of lithium from 3Q salt lake brine in Argentina as an example and in combination with specific examples. Lithium, calcium, potassium, sodium, magnesium, and boron in the brine in the examples were measured by inductively coupled plasma atomic emission spectrometry (ICP-OES), and chloride ions were measured by the silver method.

The following table lists the composition of raw salt lake brine

Example 1:

As shown in Figure 1, a kind of method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine comprises the following steps:

(1) Import 2000m ³ (mass of about 2467.4 tons) of raw salt lake brine into the pre-concentration tank for natural evaporation and concentration to precipitate potassium and sodium mixed salts. When the calcium content reaches 180g/L, calcium chloride begins to precipitate, and the pre-concentration is completed. 465m ³ (mass about 664.8 tons) of calcium-saturated brine was obtained, which was 4.1 times more concentrated than the original lithium content, Ca/Li was basically unchanged, and the lithium yield was about 96%. The specific content is shown in Table 1-1.

Table 1-1 Calcium Saturated Brine Composition Table

(2) Lead the calcium-saturated brine into the acidification tank, add hydrochloric acid and adjust the pH to about 1 to remove boron.

(3) The first natural evaporation-freezing calcium precipitation: import the acidified brine into the 1# calcium chloride pool, when the Ca ²⁺ content in the brine reaches about 185g/L, pump it into the 1# cooling crystallizer, and crystallize at the same time Pass fresh water into the jacket of the crystallizer for cooling. The cooling temperature is 4.5°C. When the solid mass concentration in the crystallizer is about 50%, the solid-liquid separation is carried out, and the first natural evaporation-freezing calcium precipitation is completed to obtain the first calcium chloride. 327.6 tons of crystallization and about 228m ³ of primary decalcified brine (mass about 325.3 tons). The primary decalcified brine is 7.8 times more concentrated than the lithium content of the original halogen, the Ca/Li ratio is reduced by 50.5%, and the lithium yield is about 89%. The specific content is shown in Table 1-2.

Table 1-2 Component content of 1st decalcification brine

(4) The second natural evaporation-freezing calcium precipitation: import the first decalcified brine into the 2# calcium chloride pool for natural evaporation and concentration. When the Ca ²⁺ content in the brine reaches about 200g/L, pump it into 2# for cooling In the crystallizer, at the same time, fresh water is passed into the jacket of the crystallizer for cooling. The cooling temperature is 4.1°C. When the solid mass concentration in the crystallizer is about 49%, the solid-liquid separation is carried out, and the second natural evaporation-freezing calcium precipitation is completed. 136.1 tons of secondary calcium chloride crystals and approximately 97.5 m ³ of secondary decalcified brine (mass approximately 139.2 tons) were obtained. The lithium content of the secondary decalcified brine is 15.7 times more concentrated than that of the original halogen, the Ca/Li ratio is reduced by 76.9%, and the lithium yield is about 76%. The specific content is shown in Table 1-3.

Table 1-3 Component content of 2nd decalcification brine

(5) The third natural evaporation-freezing calcium precipitation: import the second decalcified brine into the 3# calcium chloride pool for natural evaporation and concentration. When the Ca ²⁺ content in the brine reaches about 189g/L, pump it into 3# for cooling In the crystallizer, at the same time, fresh water is passed into the jacket of the crystallizer for cooling. The cooling temperature is 4.3°C. When the solid mass concentration in the crystallizer is about 48%, the solid-liquid separation is carried out, and the third natural evaporation-freezing calcium precipitation is completed. Obtain 55.9 tons of 3 times calcium chloride crystallization and 3 times decalcified brine about 41.6m ³ (mass about 60.5 tons), which is 30.5 times more concentrated than the original halogen lithium content, Ca/Li ratio is 4.85, a drop of 88.7%, lithium yield It is about 63%, and the specific content is shown in Table 1-4.

Table 1-4 Component content of 3 times decalcified brine

After the original brine was pre-concentrated, acidified to remove boron and 3 times of natural evaporation-freezing calcium precipitation, the isolated lithium-enriched brine was 41.6m ³ , the lithium was concentrated to 31.25g/L, the Ca/Li ratio was reduced to 4.85, and the total lithium yield Above 60%, the separation efficiency of calcium and lithium is high, and the loss of lithium is small.

Example 2:

As shown in Figure 1, a kind of method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine comprises the following steps:

(1) Import 2500m ³ (mass about 3084.2 tons) of raw salt lake brine into the pre-concentration tank for natural evaporation and concentration to precipitate potassium and sodium mixed salts. When the calcium content reaches 160g/L, calcium chloride begins to precipitate, and the pre-concentration is completed. 658m ³ (mass about 916.6 tons) of calcium-saturated brine was obtained, which was 3.7 times more concentrated than the lithium content of the original halogen, Ca/Li remained basically unchanged, and the lithium yield was about 96.7%. The specific content is shown in Table 2-1.

Table 2-1 Calcium-saturated brine composition content table

(2) Lead the calcium-saturated brine into the acidification tank, add hydrochloric acid and adjust the pH to about 0.7 to remove boron.

(3) The first natural evaporation-freezing calcium precipitation: import the acidified brine into the 1# calcium chloride pool, when the Ca ²⁺ content in the brine reaches about 185g/L, pump it into the 1# cooling crystallizer, and crystallize at the same time The original brine is passed into the jacket of the crystallizer for cooling. The cooling temperature is -3.4°C. When the solid mass concentration in the crystallizer is about 51%, the solid-liquid separation is carried out, and the first natural evaporation-freezing calcium precipitation is completed to obtain the first chlorine. 406.7 tons of calcium oxide crystals and about 276m ³ of primary decalcified brine (mass about 385.2 tons). The primary decalcified brine is 8.2 times more concentrated than the lithium content of the original halogen, the Ca/Li ratio is reduced by 58.9%, and the lithium yield is about 90%. The specific content is shown in Table 2-2.

Table 2-2 1st decalcification brine component content list

(4) The second natural evaporation-freezing calcium precipitation: import the first decalcified brine into the 2# calcium chloride pool, and when the Ca ²⁺ content in the brine reaches about 170g/L, pump it into the 2# cooling crystallizer, At the same time, raw brine is passed into the jacket of the crystallizer for cooling, and the cooling temperature reaches -3.4°C. When the solid mass concentration in the crystallizer is about 41%, solid-liquid separation is carried out, and the second natural evaporation-freezing calcium precipitation is completed to obtain 2 134.7 tons of calcium hypochloride crystals and about 142m ³ (mass about 197.5 tons) of twice decalcified brine, 14.4 times more concentrated than the original lithium content, Ca/Li ratio decreased by 78.3%, lithium yield was about 81%, specifically The content is shown in Table 2-3.

Table 2-3 Component content of 2nd decalcification brine

(5) The third natural evaporation-freezing calcium precipitation: import the second decalcified brine into the 3# calcium chloride pool, and when the Ca ²⁺ content in the brine reaches about 170g/L, pump it into the 3# cooling crystallizer, At the same time, raw brine is passed into the jacket of the crystallizer for cooling, and the cooling temperature reaches -3.4°C. When the solid mass concentration in the crystallizer is about 41%, solid-liquid separation is carried out, and the third natural evaporation-freezing calcium precipitation is completed to obtain 3 65.3 tons of calcium hypochloride crystallization and 66.9m ³ (mass of about 93.1 tons) of 3 times decalcified brine, 27.2 times more concentrated than the original lithium content, 89.9% drop in Ca/Li ratio, and 73% lithium yield. See Table 2-4 for specific content.

Table 2-4 Component content of 3 times decalcified brine

(6) The 4th natural evaporation-freezing calcium precipitation: import the 3 times decalcified brine into the 4# calcium chloride pool, when the Ca ²⁺ content in the brine reaches about 140g/L, pump it into the 4# cooling crystallizer, At the same time, the original brine is passed into the jacket of the crystallizer for cooling, and the cooling temperature reaches -3.4°C. When the solid mass concentration in the crystallizer is about 25%, the solid-liquid separation is carried out, and the third natural evaporation-freezing calcium precipitation is completed to obtain 4 19.8 tons of calcium hypochloride crystals and 42.3 m ³ (mass of about 60.3 tons) of 4 times decalcified brine, 36.2 times more concentrated than the original lithium content, 92.1% decrease in Ca/Li ratio, and 61% lithium yield. See Table 2-5 for specific content.

Table 2-5 Component content of 4 times decalcified brine

After the original brine is pre-concentrated, acidified to remove boron, and 4 times of natural evaporation-freezing calcium precipitation, the isolated lithium-enriched brine is 42.3m ³ , the lithium is concentrated to 37.11g/L, the Ca/Li ratio is reduced to 3.41, and the total lithium yield Above 60%, the separation efficiency of calcium and lithium is high, and the loss of lithium is small.

Example 3:

As shown in Figure 1, a kind of method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine comprises the following steps:

(1) Import 2500m ³ (mass about 3084.2 tons) of raw salt lake brine into the pre-concentration tank for natural evaporation and concentration to precipitate potassium and sodium mixed salts. When the calcium content reaches 200g/L, calcium chloride begins to precipitate, and the pre-concentration is completed. 528.7m ³ (about 774.6 tons in mass) of calcium-saturated brine was obtained, which was 4.6 times more concentrated than the lithium content of the original halide, Ca/Li was basically unchanged, and the lithium yield was about 96.8%. The specific content is shown in Table 3-1.

Table 3-1 Component content of calcium-saturated brine

(2) Lead the calcium-saturated brine into the acidification tank, add hydrochloric acid and adjust the pH to about 0.6 to remove boron.

(3) The first natural evaporation-freezing calcium precipitation: import the acidified brine into the 1# calcium chloride pool, and when the Ca ²⁺ content in the brine reaches about 215g/L, pump it into the 1# cooling crystallizer and crystallize at the same time The original brine is passed into the jacket of the crystallizer for cooling. The cooling temperature is 7.8°C. When the solid mass concentration in the crystallizer is about 37.5%, the solid-liquid separation is carried out, and the first natural evaporation-freezing calcium precipitation is completed to obtain the first chlorination. 271.1 tons of calcium crystals and about 317.6m ³ of primary decalcified brine (mass about 385.2 tons). The primary decalcified brine is 6.9 times more concentrated than the lithium content of the original halogen, the Ca/Li ratio is reduced by 45.2%, and the lithium yield is about 88%. The specific content is shown in Table 3-2.

Table 3-2 Component content of 1st decalcification brine

(4) The second natural evaporation-freezing calcium precipitation: import the first decalcified brine into the 2# calcium chloride pool, and when the Ca ²⁺ content in the brine reaches about 192g/L, pump it into the 2# cooling crystallizer, At the same time, the original brine is passed into the jacket of the crystallizer for cooling, and the cooling temperature is 8.2°C. When the solid mass concentration in the crystallizer is about 55%, the solid-liquid separation is carried out, and the second natural evaporation-freezing calcium precipitation is completed to obtain 2 times 185.9 tons of calcium chloride crystallization and about 107.4m ³ (mass of about 153.2 tons) of 2 times decalcified brine, which is 17.7 times concentrated than the original lithium content, the Ca/Li ratio decreased by 80%, and the lithium yield was about 76%. The content is shown in Table 3-3.

Table 3-3 Component content table of 2 times decalcification brine

(5) The third natural evaporation-freezing calcium precipitation: import the second decalcified brine into the 3# calcium chloride pool, and when the Ca ²⁺ content in the brine reaches about 171g/L, pump it into the 3# cooling crystallizer, At the same time, raw brine is passed into the jacket of the crystallizer for cooling, and the cooling temperature reaches 7.6°C. When the solid mass concentration in the crystallizer is about 37%, solid-liquid separation is carried out, and the third natural evaporation-freezing calcium precipitation is completed, and three times 50.9 tons of calcium chloride crystals and about 59.7m ³ (mass of about 87.7 tons) of 3 times decalcified brine, 28.3 times more concentrated than the original lithium content, 86.5% decrease in Ca/Li ratio, and about 67.5% lithium yield. Specifically The content is shown in Table 3-4.

Table 3-4 Component content of 3 times decalcified brine

(6) The 4th natural evaporation-freezing calcium precipitation: import the 3 times decalcified brine into the 4# calcium chloride pool, when the Ca ²⁺ content in the brine reaches about 176g/L, pump it into the 4# cooling crystallizer, At the same time, raw brine is passed into the jacket of the crystallizer for cooling, and the cooling temperature reaches 7.3°C. When the solid mass concentration in the crystallizer is about 28%, the solid-liquid separation is carried out, and the third natural evaporation-freezing calcium precipitation is completed, and 4 times are obtained. 23.1 tons of calcium chloride crystallization and about 40.8m ³ (mass about 59.8 tons) of 4 times decalcified brine, which is 36 times more concentrated than the original halogen lithium content, the Ca/Li ratio decreased by 90.7%, and the lithium yield was about 58.8%. The content is shown in Table 3-5.

Table 3-5 Component content table of 4th decalcification brine

After the original brine is pre-concentrated, acidified to remove boron and 4 times of natural evaporation-freezing calcium precipitation, the isolated lithium-enriched brine is 40.8m ³ , lithium is concentrated to 36.89g/L, the Ca/Li ratio is reduced to 4.0, and the total lithium yield Above 58%, the separation efficiency of calcium and lithium is high, and the loss of lithium is small.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

A method for removing calcium and enriching lithium from salt lake brine with high calcium-lithium ratio, characterized in that: comprising the following steps: (1) Naturally evaporate the lithium-containing raw brine of the calcium chloride type salt lake to precipitate potassium and sodium mixed salts, and then acidify the brine to remove boron; (2) The brine treated in step (1) is subjected to at least one natural evaporation-freezing calcium precipitation operation, wherein the freezing calcium precipitation operation is to lower the temperature of the brine to precipitate calcium chloride crystals, and then perform solid-liquid separation to obtain Lithium-enriched concentrated brine. A method for decalcifying and enriching lithium from high-calcium-lithium ratio salt lake brine according to claim 1, characterized in that: in step (1), when the calcium in the brine is saturated and calcium chloride crystals will be separated out, the brine Carry out acidification to remove boron. A method for decalcifying and enriching lithium from salt lake brine with high calcium-lithium ratio according to claim 1, characterized in that: the pH of the brine after acidification in step (1) is 0.5-3. A method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine according to claim 1, characterized in that: in step (2), when the brine naturally evaporates to a calcium content above 140g/L, then It performs freezing and calcium precipitation operation. A method for decalcifying and enriching lithium from salt lake brine with a high calcium-lithium ratio according to claim 1, characterized in that in step (2), the temperature of the brine is lowered to below 15° C. by means of a freeze crystallization device. A method for decalcifying and enriching lithium from high-calcium-lithium ratio salt lake brine according to claim 5, characterized in that: the freeze crystallization device is a cooling crystallizer with a cooling jacket, and the cooling jacket is equipped with cooling medium. A method for removing calcium and enriching lithium from salt lake brine with high calcium-lithium ratio according to claim 1, characterized in that: the brine in step (2) is cooled by using fresh water and/or the original brine of the salt lake. A method of decalcifying and enriching lithium from high calcium-lithium ratio salt lake brine according to claim 6, characterized in that: in step (2), when the calcium chloride crystallization mass concentration in the cooling crystallizer is 20- At 70%, carry out solid-liquid separation. A method for decalcifying and enriching lithium from high calcium-lithium ratio salt lake brine according to claim 1, characterized in that: in step (2), at least three natural evaporation-freezing calcium precipitation operations are performed. A method for removing calcium and enriching lithium from high calcium-lithium ratio salt lake brine according to claim 1, characterized in that: the Ca/Li mass ratio in the concentrated lithium-enriched brine obtained in step (2) is below 10 .

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