Method for extracting lithium and potassium from carbonic acid type salt lake brine

Abstract

The invention discloses a method for extracting lithium and potassium from carbonic acid type salt lake brine. The method comprises the following steps: carrying out pre-evaporation treatment on carbonic acid type salt lake brine to prepare first brine; performing Li < + > adsorption and desorption treatment on the first brine to prepare second brine and desorption liquid; the desorption solution is subjected to natural evaporation treatment, and LiCl is prepared; and performing freezing, natural evaporation and cold crystallization treatment on the second brine to prepare KCl, thereby realizing extraction of lithium and potassium in the carbonic acid type salt lake brine. According to the method, a salt lake resource development mode of lithium first and potassium second is constructed, the method specifically comprises a process of pre-evaporation, continuous ion exchange, freezing, natural evaporation and cold crystallization, resource utilization of lithium and potassium in the carbonic acid type salt lake brine is achieved, and the lithium yield is increased.

Description

Technical Field

[0001] This invention belongs to the field of comprehensive utilization technology of salt lake brine resources, specifically relating to a method for extracting lithium and potassium from carbonated salt lake brine. Background Technology

[0002] Lithium and potassium in salt lake brines are important resources. Currently, potassium extraction and separation technologies are relatively mature and well-developed, forming a complete industrial chain. Examples include the 8 million-ton-per-year potash fertilizer production line of Qinghai Salt Lake Industry Co., Ltd., and the potassium sulfate production line in Lop Nur Salt Lake.

[0003] Research on lithium extraction and separation methods from salt lake resources is very active, and several production lines have been established. For example, Lanke Lithium, Zangge Lithium, and Jintai Lithium use adsorption methods for lithium extraction, while Minmetals, Qinghai Lithium, and Hengxinrong Lithium use membrane methods.

[0004] Currently, there is no complete technology or industrial demonstration for the simultaneous extraction of lithium and potassium from carbonated salt lake brines in China. For example, in Zabuye Salt Lake, lithium carbonate is currently prepared using a precipitation method, and potassium resources are then utilized later. This process results in significant lithium resource loss. In Qinghai, salt lake resources are first utilized using potassium resources, and then lithium is extracted from the tailings. The drawback of this process is also significant lithium resource loss. Summary of the Invention

[0005] The main objective of this invention is to provide a method for extracting lithium and potassium from carbonated salt lake brine, in order to overcome the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes:

[0007] This invention provides a method for extracting lithium and potassium from carbonated salt lake brine, comprising:

[0008] The first brine was obtained by pre-evaporating carbonate-type salt lake brine.

[0009] The first brine was subjected to Li + Adsorption and desorption processes were performed to obtain a second brine and a desorption solution.

[0010] The eluent was subjected to natural evaporation to obtain LiCl;

[0011] Furthermore, the second brine is subjected to freezing, natural evaporation, and cold crystallization to produce KCl, thereby enabling the extraction of lithium and potassium from carbonate-type salt lake brine.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention constructs a "lithium first, potassium later" salt lake resource development model, which specifically includes the process of "pre-evaporation-continuous ion exchange-freezing-natural evaporation-cold crystallization", realizing the resource utilization of both lithium and potassium in carbonate salt lake brine and improving the lithium yield (the yield of the prior art is less than 90%). Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a typical embodiment of the present invention for extracting lithium and potassium from carbonated salt lake brine. Detailed Implementation

[0015] In view of the deficiencies of the existing technology, the inventors of this case, through long-term research and extensive practice, have been able to propose the technical solution of this invention, which mainly establishes a process method of "pre-evaporation-continuous ion exchange-freezing-natural evaporation-cold crystallization" for carbonate-type salt lake lithium and potassium resources.

[0016] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] Specifically, as one aspect of the technical solution of this invention, a method for extracting lithium and potassium from carbonated salt lake brine includes:

[0018] The first brine was obtained by pre-evaporating carbonate-type salt lake brine.

[0019] The first brine was subjected to Li + Adsorption and desorption processes were performed to obtain a second brine and a desorption solution.

[0020] The eluent was subjected to natural evaporation to obtain LiCl;

[0021] Furthermore, the second brine is subjected to freezing, natural evaporation, and cold crystallization to produce KCl, thereby enabling the extraction of lithium and potassium from carbonate-type salt lake brine.

[0022] In some preferred embodiments, the method specifically includes: pre-evaporating carbonate-type brine in summer to obtain a first brine; wherein the pre-evaporation treatment at least satisfies the following condition: the first brine contains K + The concentration is ≤2.00 wt%.

[0023] In some preferred embodiments, the carbonated brine comprises the following components calculated by mass percentage: K + 1.00–1.20 wt%, Mg 2+ 0.02–0.06 wt%, Li + 0.016~0.020wt%, Cl - 7.50–8.10 wt%, SO4 2- 1.15–1.25 wt% and CO3 2- 1.16–1.26 wt%.

[0024] In some preferred embodiments, the method specifically includes:

[0025] The first brine is fed into a continuous ion exchanger for Li... + Adsorption treatment was used to obtain a second brine.

[0026] The continuous ion exchange device was subjected to a 0.3–0.4 mol / L HCl solution to obtain the eluent;

[0027] The eluent was subjected to natural evaporation to obtain a third brine and crude NaCl; wherein, the third brine contained Li + The concentration is 0.65–0.75 wt%.

[0028] Furthermore, the third brine is subjected to further natural evaporation to obtain the LiCl product.

[0029] Furthermore, the yield of the LiCl product is ≥90%.

[0030] In some preferred embodiments, the method specifically includes:

[0031] The second brine was frozen at -17.0 to -13.0°C, and then subjected to solid-liquid separation to obtain the fourth brine and the first solid product.

[0032] The fourth brine is subjected to natural evaporation, followed by solid-liquid separation to obtain a fifth brine and a second solid product; wherein, K in the fifth brine + The concentration was 3.30–3.40 wt%.

[0033] The fifth brine is further subjected to natural evaporation. When the mass ratio of the obtained brine to the carbonated salt lake brine is 2.5 to 3.5:100, evaporation is stopped and solid-liquid separation is carried out to obtain the sixth brine and the third solid product.

[0034] Furthermore, the first solid product and the second solid product are used to prepare sodium products (such as caustic soda).

[0035] Further, the method specifically includes: adding the third solid product to Na at a temperature of 80-90°C. + -K + -Cl - The product is dissolved in a saturated system, then separated and filtered. The obtained liquid product is then naturally cooled to obtain KCl product and liquid by-product.

[0036] Furthermore, the yield of the KCl product is ≥65%.

[0037] Furthermore, the liquid phase byproducts are recycled as mother liquor.

[0038] In some more specific implementation plans, taking a carbonate salt lake in Tibet as an example, the main technical components are as follows, and the process flow is shown below. Figure 1 :

[0039] (1) Brine composition: K + 1.00–1.20 wt%, Mg 2+ 0.02–0.06 wt%, Li + 0.016~0.020wt%, Cl - 7.50–8.10 wt%, SO4 2- 1.15–1.25 wt% and CO3 2- 1.16–1.26 wt%, of which Na + The content was obtained by subtraction, and will not be further elaborated below.

[0040] (2) A certain amount of brine (L1, the aforementioned carbonate-type salt lake brine) is subjected to slight natural evaporation. Taking advantage of the high evaporation rate of the salt lake in summer, the brine is pre-evaporated in summer to obtain concentrated brine (L2, the aforementioned first brine). The key control point for the pre-evaporation process is to prevent salt precipitation. That is, K + Concentration control: K in brine + The concentration is close to or reaches 2.00 wt.%.

[0041] (3) The brine (L2) is transported to a continuous ion exchange unit to treat the Li in the brine. +Adsorption separation was performed, and the adsorbed brine (L3, the aforementioned second brine) was transported to a refrigeration unit for freezing. Li was treated with 0.3–0.4 M HCl. + The solution was analyzed, and LiCl was obtained by natural evaporation of the eluent (L4). The chemical compositions of L3 and L4 are shown in Tables 1 and 2.

[0042] Table 1 (Unit: wt%)

[0043]

[0044] Table 2 (Unit: wt%)

[0045]

[0046] (4) The above-mentioned brine (L3) was frozen using the low-temperature cold energy of the salt lake in winter. The freezing conditions were: brine temperature -17.0 to -13.0℃. The composition of the frozen brine (L6, the aforementioned fourth brine) is shown in Table 3, and the chemical composition of the solid mineral S3 (the aforementioned first solid product) is shown in Table 4.

[0047] Table 3 (Unit: wt%)

[0048]

[0049] Table 4

[0050]

[0051] (5) The L6 above was naturally evaporated, and brine K was detected. + The content reached 3.30 wt% to 3.40 wt%, and solid-liquid separation was performed. The chemical compositions of the brine (L7, the aforementioned fifth brine) and solid (S6) (the aforementioned second solid product) obtained after separation are shown in Table 5.

[0052] Table 5

[0053]

[0054] (6) Continue evaporating L7 and measure the weight of the brine. Stop evaporation when the remaining brine weight accounts for 2.5-3.5% of the weight of L1 (brine formation rate), and perform solid-liquid separation. The chemical compositions of the separated brine (L8, the aforementioned sixth brine) and solid (S8) (the aforementioned third solid product) are shown in Table 6:

[0055] Table 6

[0056]

[0057] (7) The LA solution obtained in (3) above was naturally evaporated, and Li was detected in the brine.+ After the content reaches 0.65wt% to 0.75wt%, solid-liquid separation is performed. The separated liquid phase (L5, the aforementioned third brine) has NaCl as the main solid phase. The chemical composition of L5 is shown in Table 7.

[0058] Table 7

[0059]

[0060] (8) The above L5 continues to evaporate naturally until it is dry, and LiCl product is obtained with a yield of over 90.0%.

[0061] (9) Use S8 as a raw material for preparing KCl. Add S8 to Na at 90℃. + -K + -Cl - Dissolve in a saturated system (mother liquor). After complete dissolution, separate and filter. The resulting solid phase is sodium chloride solid. The hot solution is used as the mother liquor for cooling and crystallizing KCl.

[0062] (10) The obtained liquid phase (the above hot solution) is placed indoors to cool naturally and reach equilibrium before solid-liquid separation is performed. The liquid phase is recycled as the mother liquor. + -K + -Cl - The saturated system (mother liquor) has a solid phase of KCl product with a purity greater than 70% and an overall yield of 65%. The chemical composition of the circulating mother liquor at room temperature is: K... + 5.31–5.55 wt%, Na + 6.99–7.66 wt%, Cl - : 15.45~17.16wt%.

[0063] The development sequence of lithium and potassium resources in carbonate-type salt lakes in this invention is: "lithium first, then potassium".

[0064] This invention establishes a process for preparing lithium and potassium resources from carbonate-type salt lakes using a "pre-evaporation-continuous ion exchange-freezing-natural evaporation-cold crystallization" method. Natural evaporation comprises two parts: the LiCl product obtained after natural evaporation of the eluent, and the potassium mixed salt obtained after lithium adsorption in the brine, which is then further prepared into KCl through natural evaporation. Freezing is used to control the SO4 content in the brine. 2- and CO3 2- "Pre-evaporation", "evaporation" and "freezing" all utilize natural energy and do not consume additional energy.

[0065] The present invention is as follows Figure 1 In the process, the node control for evaporation-I is K in the brine. + The content shall not exceed 2.00 wt%; the evaporation-III node control shall be based on the K content in the brine. +Content 3.30–3.40 wt% and brine formation rate 2.5–3.5%; Evaporation-II node control is based on Li in the brine. + Content: 0.65–0.75 wt%.

[0066] The eluent in this invention undergoes natural evaporation, unlike the forced evaporation used in existing production processes.

[0067] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0068] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0069] Example 1

[0070] (1) Take a certain amount of salt lake brine (L1), 25.0 kg. The chemical composition of L1 is: K + -1.00 wt.%; Mg 2+ -0.02wt.%; Li + -0.016wt.%; Cl - -7.50 wt.%; SO4 2- -1.15 wt.%; CO3 2- -1.16wt.%.

[0071] (2) The above-mentioned brine L1 was pre-evaporated, and the resulting brine L2, weighing 20.5 kg, had the following chemical composition: K + -1.22 wt.%; Mg 2+ -0.03wt.%; Li + -0.021wt.%; Cl - -8.15 wt.%; SO4 2- -1.15 wt.%; CO3 2- -1.16wt.%.

[0072] (3) The L2 brine is introduced into a continuous ion exchange device for Li + After adsorption, the adsorbed tail brine L3 was obtained. L3 was then frozen using the low winter temperatures of the salt lake, followed by solid-liquid separation to obtain brine L6 and solid phase S3. L6 weight: 14.9 kg; S3 weight: 5.20 kg. The chemical compositions of L6 and S3 are shown in Tables 8 and 9.

[0073] Table 8 Unit: wt%

[0074]

[0075] Table 9 Unit: wt%

[0076]

[0077] (4) 14.9 kg of L6 brine was naturally evaporated, and K was detected in the brine. + The content was 3.30 wt%. Solid-liquid separation was performed to obtain brine (L7) and solid (S6) after separation. The weights of L7 and S6 were 8.74 kg and 2.11 kg, respectively. The corresponding chemical compositions are shown in Table 10.

[0078] Table 10

[0079]

[0080] (5) Continue evaporating L7 and measure the weight of the brine. Stop evaporation when the remaining brine weight accounts for 2.5% of the weight of L1 (brine formation rate) and perform solid-liquid separation. The brine (L8) and solid (S8) obtained after separation have weights of 0.22 kg and 0.88 kg, respectively. The corresponding chemical compositions are shown in Table 11.

[0081] Table 11

[0082]

[0083] (6) Use S8 as a raw material for preparing KCl. Add 0.88 kg of S8 to Na at 90 °C. + -K + -Cl - Dissolve in a saturated system (mother liquor). After complete dissolution, separate and filter. The obtained solid phase is sodium chloride solid. The obtained liquid phase is placed indoors to cool naturally and equilibrate before solid-liquid separation. The liquid phase is recycled as mother liquor, and the solid phase is KCl product. The weight of the obtained product is 0.40 kg, the purity is greater than 91.9%, and the total yield is 76.0%.

[0084] (7) In step (3) above, the L2 brine is introduced into a continuous ion exchange device for Li + Adsorption, using 0.3–0.4 M HCl for Li + The analysis was performed, and the amount of hydrochloric acid used was determined as follows: the volume ratio of adsorbent to hydrochloric acid was 1:0.8. The eluent (L4) was allowed to evaporate naturally, and Li was detected in the liquid phase. + After reaching a concentration of 0.65 wt%, solid-liquid separation was performed to obtain liquid phase L5 and solid sodium chloride. The chemical compositions of L4 and L5 are shown in Table 12.

[0085] Table 12 Unit: wt%

[0086]

[0087] (8) L5 continued to evaporate naturally until it was completely dry. The solid obtained was LiCl product. The weight of the product was 3.12 kg, the purity was greater than 70.5%, and the yield was 90.2%.

[0088] Example 2

[0089] (1) Take a certain amount of salt lake brine (L1), 25.0 kg. The chemical composition of L1 is: K + -1.20 wt.%; Mg 2+ -0.06wt.%; Li + -0.020wt.%; Cl - -8.10 wt.%; SO4 2- -1.25wt.%; CO3 2- -1.26wt.%.

[0090] (2) The above-mentioned brine L1 was pre-evaporated, and the resulting brine L2, weighing 18.7 kg, had the following chemical composition: K + -1.61 wt.%; Mg 2+ -0.06wt.%; Li + -0.025wt.%; Cl - -8.29wt.%; SO4 2- -1.25wt.%; CO3 2- -1.26wt.%.

[0091] (3) The L2 brine is introduced into a continuous ion exchange device for Li + After adsorption, the adsorbed tail brine L3 was obtained. L3 was then frozen using the low winter temperatures of the salt lake, followed by solid-liquid separation to obtain brine L6 and solid phase S3. L6 weight: 14.7 kg; S3 weight: 5.21 kg. The chemical compositions of L6 and S3 are shown in Tables 13 and 14.

[0092] Table 13 Unit: wt%

[0093]

[0094] Table 14 Unit: wt%

[0095]

[0096] (4) 14.7 kg of L6 brine was allowed to evaporate naturally, and K was detected in the brine. +The content was 3.40 wt%. Solid-liquid separation was performed, yielding brine (L7) and solid (S6) with weights of 8.74 kg and 2.17 kg respectively. The corresponding chemical compositions are shown in Table 15.

[0097] Table 15

[0098]

[0099] (5) Continue evaporating L7 and measure the weight of the brine. Stop evaporation when the remaining brine weight accounts for 3.5% of the weight of L1 (brine formation rate) and perform solid-liquid separation. The brine (L8) and solid (S8) obtained after separation have weights of 0.32 kg and 0.89 kg, respectively. The corresponding chemical compositions are shown in Table 16.

[0100] Table 16

[0101]

[0102] (6) Use S8 as a raw material for preparing KCl. Add 0.89 kg of S8 to Na at 90 °C. + -K + -Cl - Dissolve in a saturated system (mother liquor). After complete dissolution, separate and filter. The obtained solid phase is sodium chloride solid. The obtained liquid phase is placed indoors to cool naturally and equilibrate before solid-liquid separation. The liquid phase is recycled as mother liquor, and the solid phase is KCl product. The weight of the obtained product is 0.42 kg, the purity is greater than 92.3%, and the total yield is 67.3%.

[0103] (7) In step (3) above, the L2 brine is introduced into a continuous ion exchange device for Li + Adsorption, using 0.3–0.4 M HCl for Li + The hydrochloric acid dosage was determined by the following analysis: the volume ratio of adsorbent to hydrochloric acid was 1:0.9. The eluent (L4) was allowed to evaporate naturally, and Li was detected in the liquid phase. + After reaching a concentration of 0.75 wt%, solid-liquid separation was performed to obtain liquid phase L5 and sodium chloride solid. The chemical compositions of L4 and L5 are shown in Table 7, and their corresponding chemical compositions are shown in Table 17.

[0104] Table 17 Unit: wt%

[0105]

[0106] (8) L5 continued to evaporate naturally until it was completely dry. The resulting solid was LiCl. The weight of the product was 2.5 kg, and the purity was greater than 85%.

[0107] Example 3

[0108] (1) Take a certain amount of salt lake brine (L1), 25.0 kg. The chemical composition of L1 is: K + -1.10 wt.%; Mg 2+ -0.03wt.%; Li + -0.019wt.%; Cl - -8.00 wt.%; SO4 2- -1.20 wt.%; CO3 2- -1.20wt.%.

[0109] (2) The above-mentioned brine L1 was pre-evaporated, and the resulting brine L2, weighing 19.5 kg, had the following chemical composition: K + -1.41 wt.%; Mg 2+ -0.05wt.%; Li + -0.023wt.%; Cl - -8.21 wt.%; SO4 2- -1.20 wt.%; CO3 2- -1.19wt.%.

[0110] (3) The L2 brine is introduced into a continuous ion exchange device for Li + After adsorption, the adsorbed tail brine L3 was obtained. L3 was then frozen using the low winter temperatures of the salt lake, followed by solid-liquid separation to obtain brine L6 and solid phase S3. L6 weight: 14.8 kg; S3 weight: 5.14 kg. The chemical compositions of L6 and S3 are shown in Tables 18 and 19.

[0111] Table 18 Unit: wt%

[0112]

[0113] Table 19 Unit: wt%

[0114]

[0115] (4) 14.8 kg of L6 brine was allowed to evaporate naturally, and K was detected in the brine. + The brine (L7) and solid (S6) were separated after a solid-liquid separation process, with weights of 8.74 kg and 2.10 kg respectively. Their chemical compositions are shown in Table 20.

[0116] Table 20

[0117]

[0118] (5) Continue evaporating L7 and measure the weight of the brine. Stop evaporation when the remaining brine weight accounts for 3.0% of the weight of L1 (brine formation rate) and perform solid-liquid separation. The brine (L8) and solid (S8) obtained after separation have weights of 0.262 kg and 0.90 kg, respectively. The corresponding chemical compositions are shown in Table 21.

[0119] Table 21

[0120]

[0121] (6) Use S8 as a raw material for preparing KCl. Add 0.90 kg of S8 to Na at 90 °C. + -K + -Cl - Dissolve in a saturated system (mother liquor). After complete dissolution, separate and filter. The obtained solid phase is sodium chloride solid. The obtained liquid phase is placed indoors to cool naturally and equilibrate before solid-liquid separation. The liquid phase is recycled as mother liquor, and the solid phase is KCl product. The weight of the obtained product is 0.44 kg, the purity is greater than 90.6%, and the total yield is 75.3%.

[0122] (7) In step (3) above, the L2 brine is introduced into a continuous ion exchange device for Li + Adsorption, using 0.3-0.4M HCl on Li + The determination of the hydrochloric acid dosage was as follows: the volume ratio of adsorbent to hydrochloric acid was 1:0.8–0.9. The eluent (L4) was allowed to evaporate naturally, and Li was detected in the liquid phase. + After reaching a concentration of 0.70 wt%, solid-liquid separation was performed to obtain liquid phase L5 and sodium chloride solid. The chemical compositions of L4 and L5 are shown in Table 22.

[0123] Table 22 Unit: wt%

[0124]

[0125] (8) L5 continued to evaporate naturally until it was completely dry. The solid obtained was LiCl product. The weight of the product was 3.61 kg, the purity was greater than 73.2%, and the yield was 91.2%.

[0126] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0127] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for extracting lithium and potassium from carbonated salt lake brine, characterized in that, include: The first brine was obtained by pre-evaporating carbonate-type salt lake brine. The first brine was subjected to Li+ adsorption and desorption treatment to obtain a second brine and a desorption solution. The eluent was subjected to natural evaporation to obtain LiCl; Furthermore, the second brine is subjected to freezing, natural evaporation, and cold crystallization to produce KCl, thereby enabling the extraction of lithium and potassium from carbonate-type salt lake brine.

2. The method according to claim 1, characterized in that, Specifically, it includes: In summer, the carbonate-type salt lake brine is pre-evaporated to obtain the first brine; wherein the pre-evaporation treatment at least satisfies the following condition: the concentration of K+ in the first brine is ≤2.00wt%.

3. The method according to claim 1, characterized in that, The carbonated brine comprises the following components by mass percentage: K + 1.00–1.20 wt%, Mg 2+ 0.02–0.06 wt%, Li + 0.016~0.020wt%, Cl - 7.50–8.10 wt%, SO4 2- 1.15–1.25 wt% and CO3 2- 1.16–1.26 wt%.

4. The method according to claim 1, characterized in that, Specifically, it includes: The first brine is fed into a continuous ion exchanger for Li... + Adsorption treatment was used to obtain a second brine. The continuous ion exchange device was subjected to a 0.3–0.4 mol / L HCl solution to obtain the eluent; The eluent was subjected to natural evaporation to obtain a third brine and crude NaCl; wherein, the third brine contained Li + The concentration is 0.65–0.75 wt%. Furthermore, the third brine is subjected to further natural evaporation to obtain the LiCl product.

5. The method according to claim 4, characterized in that: The yield of the LiCl product is ≥90%.

6. The method according to claim 1, characterized in that, Specifically, it includes: The second brine was frozen at -17.0 to -13.0°C, and then subjected to solid-liquid separation to obtain the fourth brine and the first solid product. The fourth brine is subjected to natural evaporation, followed by solid-liquid separation to obtain a fifth brine and a second solid product; wherein, K in the fifth brine + The concentration was 3.30–3.40 wt%. The fifth brine is further subjected to natural evaporation. When the mass ratio of the obtained brine to the carbonated salt lake brine is 2.5 to 3.5:100, evaporation is stopped and solid-liquid separation is carried out to obtain the sixth brine and the third solid product.

7. The method according to claim 6, characterized in that, Specifically, it includes: The third solid product was added to Na at a temperature of 80–90°C. + -K + -Cl - The product is dissolved in a saturated system, then separated and filtered. The obtained liquid product is then naturally cooled to obtain KCl product and liquid by-product.

8. The method according to claim 7, characterized in that: The yield of the KCl product is ≥65%.

9. The method according to claim 7, characterized in that: The liquid phase byproducts are recycled as mother liquor.

10. The method according to claim 6, characterized in that: The first solid product and the second solid product are used to prepare sodium products.

Images