阅读说明：本技术 一种从碳酸型盐湖卤水中提取碳酸锂的方法 (Method for extracting lithium carbonate from carbonate type salt lake brine ) 是由 裘慕贤 童敏 杨帆 殷玫婕 朱筱滢 朱荣伟 唐影华 于 2020-12-17 设计创作，主要内容包括：本发明提供了一种从碳酸型盐湖卤水中提取碳酸锂的方法,包括：对碳酸型盐湖卤水进行过滤,得到富含锂离子的产水及富含碳酸根和硫酸根的浓水；对所述含锂离子的产水进行吸附及解析,得到富含锂离子的解析液；对所述解析液进行反渗透处理以得到反渗透浓水,并对所述反渗透浓水进行蒸发浓缩,得到高锂母液；对所述富含碳酸根和硫酸根的浓水进行冷冻脱硝处理得到冷冻液；对所述冷冻液进行二次过滤及蒸发浓缩,得到碳酸钠溶液；将所述高锂母液与所述碳酸钠溶液混合,得到碳酸锂沉淀,并通过沉淀分离得到碳酸锂产品。通过过滤分离得到富含锂离子的产水及富含碳酸根的浓水,分别提纯浓缩后反应生成碳酸锂产品,提锂效果好且对环境友好。(The invention provides a method for extracting lithium carbonate from carbonate type salt lake brine, which comprises the following steps: filtering carbonate type salt lake brine to obtain water rich in lithium ions and concentrated water rich in carbonate and sulfate radicals; adsorbing and analyzing the water produced by lithium ions to obtain an analysis solution rich in lithium ions; carrying out reverse osmosis treatment on the analysis solution to obtain reverse osmosis concentrated water, and carrying out evaporation concentration on the reverse osmosis concentrated water to obtain high-lithium mother liquor; freezing and denitrating the concentrated water rich in carbonate and sulfate radicals to obtain a refrigerating fluid; carrying out secondary filtration and evaporative concentration on the refrigerating fluid to obtain a sodium carbonate solution; and mixing the high-lithium mother liquor with the sodium carbonate solution to obtain lithium carbonate precipitate, and separating the precipitate to obtain a lithium carbonate product. The water rich in lithium ions and the concentrated water rich in carbonate are obtained by filtration and separation, and are respectively purified and concentrated to react to generate a lithium carbonate product, so that the lithium extraction effect is good and the environment-friendly effect is achieved.)

1. A method for extracting lithium carbonate from carbonate type salt lake brine is characterized by comprising the following steps:

filtering carbonate type salt lake brine to obtain water rich in lithium ions and concentrated water rich in carbonate and sulfate radicals;

adsorbing and analyzing the water produced by lithium ions to obtain an analysis solution rich in lithium ions;

carrying out reverse osmosis treatment on the analysis solution to obtain reverse osmosis concentrated water, and carrying out evaporation concentration on the reverse osmosis concentrated water to obtain high-lithium mother liquor;

freezing and denitrating the concentrated water rich in carbonate and sulfate radicals to obtain a refrigerating fluid;

carrying out secondary filtration and evaporative concentration on the refrigerating fluid to obtain a sodium carbonate solution;

and mixing the high-lithium mother liquor with the sodium carbonate solution to obtain lithium carbonate precipitate, and separating the precipitate to obtain a lithium carbonate product.

2. The method for extracting lithium carbonate from carbonate lake brine as claimed in claim 1, wherein the concentration of lithium ions in the carbonate lake brine is 1.4g/L, the concentration of sulfate is 30g/L, and the concentration of carbonate is 45 g/L.

3. The method of claim 1, wherein the carbonate lake brine is filtered through a nanofiltration membrane.

4. The method of claim 1, wherein the lithium carbonate is adsorbed by the aluminum adsorbent to the water containing lithium ions.

5. The method of claim 4, wherein the lithium carbonate is extracted from the carbonate lake brine by using fresh water after the lithium ion-containing product water is adsorbed by using an aluminum adsorbent.

6. The method of claim 5, wherein the fresh water has a temperature of between 40 degrees Celsius and 50 degrees Celsius.

7. The method for extracting lithium carbonate from carbonate lake brine as claimed in claim 1, wherein the solution is subjected to reverse osmosis treatment by using an RO membrane to obtain reverse osmosis concentrated water.

8. The method for extracting lithium carbonate from carbonate lake brine as claimed in claim 1, wherein the produced water obtained by subjecting the desorption solution to reverse osmosis is reused for desorption after adsorption of the produced water containing lithium ions.

9. The method for extracting lithium carbonate from carbonate lake brine as claimed in claim 1, wherein the reverse osmosis concentrated water and/or the freezing liquid is subjected to evaporative concentration by using a steam mechanical recompression technology.

10. The method for extracting lithium carbonate from carbonate type salt lake brine as claimed in claim 1, wherein the secondary filtration of the refrigerating fluid is performed by using a high pressure nanofiltration membrane.

Technical Field

The invention relates to the technical field of water treatment, in particular to a method for extracting lithium carbonate from carbonate type salt lake brine.

Background

Lithium is an important strategic resource substance and is an indispensable important raw material of modern high-tech products. With the wide application of lithium and lithium salt and the continuous development of high and new technology, especially the rapid development of lithium battery industry in recent years, the demand of the market for lithium is rapidly increased. At present, lithium salt is mostly extracted from the ore in China, but with the continuous reduction of high-grade lithium ore and the continuous improvement of the cost of extracting lithium from the ore, and because the salt lake is rich in a large amount of lithium elements, the lithium extraction from the salt lake gradually draws attention of people. The salt lake lithium extraction has obvious resource and cost advantages compared with the ore lithium extraction.

The key point of the lithium extraction from the salt lake is that lithium ions are enriched from the salt lake brine in a low-cost mode and are separated out to be lithium concentrate. The main influencing factors of the lithium extraction in the salt lake are two: firstly, the lithium content in the salt lake is lower, the evaporation capacity of brine is higher, and the cost is relatively higher; secondly, the ion proportion relation of various minerals in the salt lake, particularly the magnesium-lithium ratio, and the smaller the magnesium-lithium ratio is, the better the magnesium-lithium ratio is. The method for extracting lithium mainly depends on the magnesium-lithium ratio of the salt lake brine, and the commonly used salt lake lithium extraction process comprises an ion selective electrodialysis method, a nanofiltration membrane method and a calcination leaching method.

In the ion selective electrodialysis method, the separation of lithium ions and magnesium ions is realized based on the selective permeability of the surface of the ion exchange membrane, but along with the progress of the reaction of the magnesium ion substrate, a dirt layer is easily generated on the surface of the ion exchange membrane, so that the membrane flux is reduced, and even the phenomenon of membrane electric breakdown failure caused by uneven distribution of current density on the surface of the membrane can occur. The nanofiltration membrane method uses a nanofiltration membrane as a separation medium, and applies a pressure difference on two sides of the membrane to ensure that components on the raw material side selectively permeate through the membrane, so as to realize effective separation of monovalent ions and divalent ions. However, the nanofiltration membrane method has high requirements on the pressure of the nanofiltration membrane separation equipment, the concentration of the raw material liquid, the structure and the charge property of the nanofiltration membrane. The calcining method is characterized in that lithium-containing brine obtained after potassium extraction and boron extraction is used as a raw material, water is evaporated to obtain lithium-containing magnesium chloride tetrahydrate, spray drying and calcining are adopted to obtain lithium-containing magnesium oxide, water is added to wash and filter the lithium to leach, calcium, magnesium and other impurities are removed by lime milk, the solution is evaporated and concentrated until the content of Li is about 2%, sodium carbonate is added to precipitate lithium carbonate, and the lithium yield is about 90%. The method is beneficial to comprehensively utilizing the lithium and magnesium resources in the salt lake brine, producing lithium carbonate and producing magnesite as a byproduct. However, the method has the problems that a large amount of dilute hydrochloric acid as a byproduct is recovered, acid mist is generated in the production process, and excessive hydrochloric acid cannot be treated. In addition, the problem of the corrosion of the brick furnace equipment caused by the acid environment of the calcination is difficult to completely solve.

Disclosure of Invention

The invention aims to provide a method for extracting lithium carbonate from carbonate type salt lake brine, which has good lithium extraction effect and is environment-friendly and suitable for high-altitude carbonate type salt lakes with inconvenient traffic.

In order to achieve the above object, the present invention provides a method for extracting lithium carbonate from carbonate salt lake brine, which is used for treating coking wastewater after biochemical treatment, and comprises:

filtering carbonate type salt lake brine to obtain water rich in lithium ions and concentrated water rich in carbonate and sulfate radicals;

adsorbing and analyzing the water produced by lithium ions to obtain an analysis solution rich in lithium ions;

carrying out reverse osmosis treatment on the analysis solution to obtain reverse osmosis concentrated water, and carrying out evaporation concentration on the reverse osmosis concentrated water to obtain high-lithium mother liquor;

freezing and denitrating the concentrated water rich in carbonate and sulfate radicals to obtain a refrigerating fluid;

carrying out secondary filtration and evaporative concentration on the refrigerating fluid to obtain a sodium carbonate solution;

and mixing the high-lithium mother liquor with the sodium carbonate solution to obtain lithium carbonate precipitate, and separating the precipitate to obtain a lithium carbonate product.

Optionally, in the carbonate type salt lake brine, the concentration of lithium ions is 1.4g/L, the concentration of sulfate radicals is 30g/L, and the concentration of carbonate radicals is 45 g/L.

Optionally, the carbonate salt lake brine is filtered by a nanofiltration membrane.

Optionally, an aluminum adsorbent is used to adsorb the water containing lithium ions.

Optionally, after the lithium ion-containing produced water is adsorbed by the aluminum adsorbent, fresh water is used for desorption.

Optionally, the temperature of the fresh water is between 40 ℃ and 50 ℃.

Optionally, performing reverse osmosis treatment on the desorption solution by using an RO membrane to obtain reverse osmosis concentrated water.

Optionally, the produced water obtained by performing reverse osmosis treatment on the desorption solution is reused for desorption after adsorption of the produced water containing lithium ions.

Optionally, the reverse osmosis concentrated water and/or the refrigerating fluid is evaporated and concentrated by adopting a steam mechanical recompression technology.

Optionally, a high-pressure nanofiltration membrane is used for secondary filtration of the refrigerating fluid.

The invention provides a method for extracting lithium carbonate from carbonate type salt lake brine, which comprises the following steps: filtering carbonate type salt lake brine to obtain water rich in lithium ions and concentrated water rich in carbonate and sulfate radicals; adsorbing and analyzing the water produced by lithium ions to obtain an analysis solution rich in lithium ions; carrying out reverse osmosis treatment on the analysis solution to obtain reverse osmosis concentrated water, and carrying out evaporation concentration on the reverse osmosis concentrated water to obtain high-lithium mother liquor; freezing and denitrating the concentrated water rich in carbonate and sulfate radicals to obtain a refrigerating fluid; carrying out secondary filtration and evaporative concentration on the refrigerating fluid to obtain a sodium carbonate solution; and mixing the high-lithium mother liquor with the sodium carbonate solution to obtain lithium carbonate precipitate, and separating the precipitate to obtain a lithium carbonate product. The method comprises the steps of obtaining lithium ion-rich produced water and carbonate-rich concentrated water through filtration and separation, respectively purifying and concentrating the produced water and the concentrated water, and reacting to generate a lithium carbonate product.

Drawings

It will be appreciated by those skilled in the art that the drawings are provided for a better understanding of the invention and do not constitute any limitation to the scope of the invention. Wherein:

fig. 1 is a process diagram of a method for extracting lithium carbonate from carbonate lake brine according to an embodiment of the present invention;

fig. 2 is a flowchart of a method for extracting lithium carbonate from carbonate lake brine according to an embodiment of the present invention.

Detailed Description

To further clarify the objects, advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is to be noted that the drawings are in greatly simplified form and are not to scale, but are merely intended to facilitate and clarify the explanation of the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently. It should be further understood that the terms "first," "second," "third," and the like in the description are used for distinguishing between various components, elements, steps, and the like, and are not intended to imply a logical or sequential relationship between various components, elements, steps, or the like, unless otherwise indicated or indicated.

As shown in fig. 1 and fig. 2, this embodiment provides a method for extracting lithium carbonate from carbonated salt lake brine, including:

step S1: filtering carbonate type salt lake brine to obtain water rich in lithium ions and concentrated water rich in carbonate and sulfate radicals;

step S2: adsorbing and analyzing the water produced by lithium ions to obtain an analysis solution rich in lithium ions;

step S3: carrying out reverse osmosis treatment on the analysis solution to obtain reverse osmosis concentrated water, and carrying out evaporation concentration on the reverse osmosis concentrated water to obtain high-lithium mother liquor;

step S4: freezing and denitrating the concentrated water rich in carbonate and sulfate radicals to obtain a refrigerating fluid;

step S5: carrying out secondary filtration and evaporative concentration on the refrigerating fluid to obtain a sodium carbonate solution;

step S6: and mixing the high-lithium mother liquor with the sodium carbonate solution to obtain lithium carbonate precipitate, and separating the precipitate to obtain a lithium carbonate product.

Specifically, the method for extracting lithium carbonate from carbonate salt lake brine provided by this embodiment is mainly used for carbonate salt lakes, and since carbonate salt lakes are generally located in plateau areas and have good surrounding natural environments, pollution to the salt lakes and the surrounding environments must be selected in order to protect the surrounding environments, an environment-friendly process is selected, the addition of foreign substances is reduced as much as possible, and the material recycling work is performed.

In the embodiment, the brine is from Zabuya salt lake, and the concentration of lithium ions, sulfate radical and carbonate radical in the carbonate salt lake brine are 1.4g/L, 30g/L and 45g/L respectively.

Because the water quality of the carbonate type salt lake contains a certain amount of sodium sulfate besides carbonate, the salt lake is recommended to be treated in winter, because the plateau climate is cold in winter, the sodium sulfate in the brine can be separated out in the form of mirabilite, so the sulfate ions in the salt lake can be greatly reduced, which is beneficial to obtaining the concentrated sodium carbonate solution subsequently, if summer comes, the sodium sulfate content is higher, then the sulfate in the filtered concentrated water is higher, the carbonate concentration is correspondingly reduced, and the water taking amount needs to be increased to meet the carbonate concentration required in the subsequent lithium precipitation.

Firstly, step S1 is executed to filter carbonate type salt lake brine to obtain product water rich in lithium ions and concentrated water rich in carbonate and sulfate. In this example, the carbonate salt lake brine was filtered and separated by a nanofiltration membrane. The separation performance of the nanofiltration membrane is superior to that of ultrafiltration and microfiltration, and compared with the reverse osmosis membrane, the nanofiltration membrane has the advantages of partial removal of monovalent ions, low process osmotic pressure, low operation pressure, energy saving and the like, and can be used for primary filtration of carbonate type salt lake brine. Of course, the filtration mode of the carbonate type salt lake brine is not limited in the application, and an ultrafiltration membrane or a reverse osmosis membrane can be used for treatment.

Next, step S2 is executed to adsorb and analyze the lithium ion-containing produced water to obtain an analysis solution rich in lithium ions. The adsorption-desorption mode is favorable for reducing the salt content in the produced water and improving the concentration of lithium ions. In this example, the water containing lithium ions was adsorbed by an aluminum adsorbent. The aluminum adsorbent has high adsorption and desorption speed, large adsorption and desorption amount and stability, and other adsorbents can be adopted, which is not limited in the application.

Further, the produced water containing lithium ions is adsorbed by an aluminum adsorbent and then analyzed by fresh water. The temperature of the fresh water is between 40 ℃ and 50 ℃, and the analysis effect is better. Specifically, after lithium ions in the produced water are absorbed into the aluminum-based adsorbent, the lithium ions are desorbed by hot fresh water, and exist in the desorption solution in the form of lithium chloride, wherein the lithium concentration of the desorption solution is equal to or slightly higher than that of the lithium ions in the produced water.

And then executing step S3, performing reverse osmosis treatment on the desorption solution to obtain reverse osmosis concentrated water, and performing evaporation concentration on the reverse osmosis concentrated water to obtain high-lithium mother liquor. In this embodiment, a reverse osmosis membrane (RO membrane) is used to perform reverse osmosis treatment on the desorption solution to obtain reverse osmosis concentrated water. The RO membrane has high filtration accuracy, and can concentrate the analytic solution and improve the concentration of lithium ions. Then, the analysis solution can be further concentrated by combining evaporation concentration treatment to obtain the high lithium mother solution with the lithium ion concentration of 20g/L-30 g/L.

In this embodiment, the reverse osmosis concentrated water is evaporated and concentrated by using a vapor mechanical recompression (MVR) technology. The vapor mechanical recompression (MVR) technology has the advantages of energy conservation, consumption reduction and low operation cost, and is a better choice.

Preferably, the produced water obtained by performing reverse osmosis treatment on the desorption solution is reused for desorption after adsorption of the produced water containing lithium ions. The water produced after reverse osmosis treatment can be used as desorption liquid to desorb the adsorbent, so that the utilization rate of resources is improved.

And step S4 is executed, and the concentrated water rich in carbonate and sulfate is subjected to freezing denitration treatment to obtain a refrigerating fluid. After the nanofiltration concentrated solution is enriched with carbonate and sulfate, the concentration of sulfate is higher, and at the moment, sodium sulfate can be further removed by a freezing denitration mode.

And then executing step S5, and carrying out secondary filtration and evaporative concentration on the refrigerating fluid to obtain a sodium carbonate solution. The concentration of the sodium carbonate solution can be further improved by concentrating the refrigerating fluid through secondary filtration and evaporative concentration. In the embodiment, the refrigerating fluid is subjected to secondary filtration by using a high-pressure nanofiltration membrane, and is subjected to evaporation concentration by using a vapor mechanical recompression (MVR) technology, so that a sodium carbonate solution with the concentration of 160-170 g/L is finally obtained.

In this embodiment, the steps S4 to S5 are to process concentrated water rich in carbonate and sulfate to obtain a sodium carbonate solution, and the steps S2 to S3 are to process water containing lithium ions to obtain a high-lithium mother solution. Therefore, the steps S4-S5 and S2-S3 can be performed synchronously, thereby improving the extraction efficiency.

And finally, executing step S6, mixing the high-lithium mother liquor with the sodium carbonate solution to obtain lithium carbonate precipitate, and separating the lithium carbonate precipitate to obtain a lithium carbonate product. In this embodiment, the high-lithium mother liquor and the sodium carbonate solution are mixed and then subjected to a chemical reaction to generate a lithium carbonate precipitate, and a final lithium carbonate product can be obtained through precipitation separation.

To sum up, the embodiment of the invention provides a method for extracting lithium carbonate from carbonate lake brine, the whole process fully utilizes the existing resources of the carbonate lake, the used external medicament amount is very small, carbonate and lithium ions are mainly separated by a membrane, then sodium carbonate solution and high-lithium mother liquor are obtained after respective purification and concentration, the sodium carbonate solution and the high-lithium mother liquor react with each other to generate a lithium carbonate product, the lithium extraction effect is good, the environment is friendly, and the method is suitable for the high-altitude carbonate lake with inconvenient traffic.

It should be understood, however, that the intention is not to limit the invention to the particular embodiments described. It will be apparent to those skilled in the art from this disclosure that many changes and modifications can be made, or equivalents modified, in the embodiments of the invention without departing from the scope of the invention. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention are still within the protection scope of the technical solution of the present invention, unless the content of the technical solution of the present invention is departed from.