A method for coupled acidification-extraction of boron from high boron solutions

Abstract

The application discloses a method for extracting boron from high-boron solution by coupling acidification and extraction. The method comprises the following steps: inputting high-boron solution, concentrated acid and extraction organic phase into an extraction unit to carry out extraction and back extraction, so as to realize separation and enrichment of boron; wherein the concentration of H3BO3 in the high-boron solution is 1-55 g / L; the extraction organic phase comprises an extractant and a diluent, and the extractant comprises a monohydric aliphatic alcohol and / or a dihydric alcohol. The application couples acidification and solvent extraction into one step, cancels the processes of freezing crystallization, solid-liquid separation and separate extraction of mother liquor, greatly reduces the number of equipment and investment, and stably reduces the concentration of raffinate boron to below 0.05 g / L by direct extraction, so that the total boron recovery rate reaches more than 99%. Meanwhile, the method is easy to realize large-scale and automation, fundamentally eliminates the risk of crystallization blockage, and significantly enhances the adaptability to the fluctuation of brine boron concentration and temperature change.

Description

Technical Field

[0001] This invention belongs to the field of boron separation technology, specifically relating to an acidification method for boron separation from high-boron solutions. Extraction coupling method for boron extraction. Background Technology

[0002] Boric acid is an important basic chemical raw material and a key component in many chemical products such as glass fiber, insulating materials, permanent magnets, ceramics, detergents, pesticides, and flame retardants. It plays a vital role in the development of numerous industries, including metallurgy, building materials, machinery, electronics, chemicals, agriculture, and pharmaceuticals. Currently, the scarcity of boron resources in China is threatening the development of related industries, especially as my country's solid boron ore resources have become increasingly depleted after decades of mining. However, the brine in the salt lakes of western my country contains abundant liquid boron ore resources.

[0003] Currently, the main methods for selectively separating boron from salt lake brine include acidification, adsorption, electrochemical methods, membrane separation, and solvent extraction. Although solvent extraction has problems such as extractant loss, it has outstanding advantages such as high selectivity, high efficiency, and flexible operation. One of the mature industrial routes for recovering boron from salt lake brine is the combined process of "acidification, freeze crystallization, and tail liquid solvent extraction". The disadvantages of the existing technology are: (1) Long process and many equipment: It requires independent acidification tanks, crystallizers, centrifugal separation equipment, and tail liquid extraction system, which requires large investment and large area. (2) High energy consumption: Freeze crystallization requires cooling a large amount of brine from room temperature to 0-10℃, which consumes a lot of cold energy and has high operating costs. (3) Limited total boron recovery rate: The single-pass crystallization recovery rate is usually 80%-90%. Although the boron remaining in the mother liquor can be recovered through extraction, the two-stage operation still has mechanical loss and emulsion entrainment loss. The overall boron recovery rate is usually 80%, which is difficult to improve further. (4) Complex operation and poor continuity: Crystallization is an intermittent or semi-continuous operation. After solid-liquid separation, the mother liquor is extracted again, and the process switching is frequent, making automation difficult. (5) The crystallization process is prone to problems such as boric acid carrying impurities and pipeline blockage, which affect product purity and operational stability. Summary of the Invention

[0004] The main objective of this invention is to provide a method for acidifying high-boron solutions. An extraction coupled boron extraction method is proposed to overcome the shortcomings of existing technologies.

[0005] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides an acidification method for high boron solutions. Methods for extracting boron through extraction coupling include: High boron solution, concentrated acid, and organic extractant are simultaneously fed into the extraction unit for extraction and back-extraction, thereby achieving the separation and enrichment of boron. The concentration of H3BO3 in the high-boron solution is 1~55 g / L; the extraction organic phase includes an extractant and a diluent, and the extractant includes a monohydric fatty alcohol and / or a diol.

[0006] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The process is greatly shortened: the acidification, freezing crystallization, centrifugation, and mother liquor collection processes are eliminated, and the number of equipment is reduced by more than half; (2) Energy consumption is greatly reduced: Freezing crystallization is completely eliminated, avoiding the consumption of a large amount of low-temperature cold energy; (3) Significantly improved boron recovery rate: Direct extraction can stably control the boron concentration in the raffinate below 0.05 g / L, and the single-pass extraction rate can reach more than 99%. The total recovery rate of the system is at least 10 percentage points higher than that of the "crystallization + extraction" combination. (4) Product purity is easy to guarantee: The extraction process is selective for boric acid, and impurity ions remain in the raffinate. High-purity boric acid can be directly obtained from the back-extraction solution. (5) Continuous and stable operation: All operations are in the liquid phase, which makes it easy to achieve large-scale and automated continuous production without the risk of crystallization blockage; (6) Strong adaptability: It has a good ability to adapt to fluctuations in boron concentration and temperature changes in brine; (7) The solvent extraction method used in this invention allows the extractant to be recycled multiple times, saving resources. Attached Figure Description

[0007] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0008] Figure 1 This is a process flow diagram of acidification-extraction coupled boron extraction in a typical embodiment of the present invention. Detailed Implementation

[0009] In view of the deficiencies of the prior art, the applicant, through long-term research and extensive practice, has proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0010] Specifically, as one aspect of the technical solution of this invention, it relates to an acidification method from a high-boron solution. Extraction coupling methods for boron extraction include: High boron solution, concentrated acid, and organic extractant are simultaneously fed into the extraction unit for extraction and back-extraction, thereby achieving the separation and enrichment of boron. The concentration of H3BO3 in the high-boron solution is 1~55 g / L; the extraction organic phase includes an extractant and a diluent, and the extractant includes a monohydric fatty alcohol and / or a diol.

[0011] In some preferred embodiments, the concentration of H3BO3 in the high-boron solution is 5~55 g / L.

[0012] In some preferred embodiments, the concentration of magnesium ions in the high-boron solution is 20–200 g / L.

[0013] In some preferred embodiments, the pH value of the high boron solution is 0 to 8.

[0014] In some preferred embodiments, the high-boron solution includes any one or more combinations of salt lake brine, underground brine, and boron ore leaching solution, but is not limited thereto.

[0015] In some preferred embodiments, the monohydric fatty alcohol includes, but is not limited to, monohydric fatty alcohols containing 6 to 16 carbon atoms.

[0016] In some preferred embodiments, the extractant includes any one or more combinations of isooctanol, 2-ethylhexanol, n-octanol, n-dodecanol, isododecanol, n-tetradecanool, isotetradecanool, n-hexadecylol, isohexadecylol, 2-ethyl-1,3-hexanediol, and 2,2,4-trimethyl-1,3-pentanediol, and is not limited thereto.

[0017] In some preferred embodiments, the diluent includes, but is not limited to, any one or more combinations of, and selected from, less water-soluble kerosene, sulfonated kerosene, aviation kerosene, benzene, xylene, carbon tetrachloride, heptanol, o-dichlorobenzene, trichlorobenzene, heptane, n-dodecane, decanol, diisobutyl ketone, 1,2-dichloroethane, butyl acetate, amyl acetate, and ionic liquids. The diluent in this invention can not only dissolve solid extractants or reduce the viscosity of liquid extractants, promoting the two-phase transfer process, but also reduce the amount of extractant used, thus lowering production costs.

[0018] Furthermore, the ionic liquid includes any one or more combinations of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids, wherein the imidazole ionic liquid includes [BMIM][PF6] and / or [EMIM][Tf2N].

[0019] In some preferred embodiments, the volume fraction of the extractant in the organic phase is 10% to 100%.

[0020] In some preferred embodiments, the concentrated acid includes any one or more combinations of concentrated hydrochloric acid, concentrated sulfuric acid, and concentrated nitric acid, but is not limited thereto. The feed rate of the concentrated acid is related to the feed rate of the brine (high boron solution) and the boron concentration. A low feed rate will reduce the extraction rate, while an excessively high feed rate will result in a low pH of the raffinate, but a higher extraction rate.

[0021] In some preferred embodiments, the concentrated acid contains H... + The concentration ranges from 0.5 to 18.5 mol / L.

[0022] In some preferred embodiments, the volume ratio of the extractable organic phase to the high boron solution is 1:5 to 5:1.

[0023] In some preferred embodiments, the extraction and back-extraction temperatures are each independently between 10°C and 40°C.

[0024] In some preferred embodiments, the volume flow ratio of the extractable organic phase to the high boron solution is 1:5 to 5:1.

[0025] In some preferred embodiments, the volume flow ratio of the high boron solution to the concentrated acid is 1:1 to 50:1.

[0026] Furthermore, the volumetric flow rate ratio of the high boron solution to the concentrated acid is 5:1 to 30:1.

[0027] In some preferred embodiments, the extraction unit includes an extraction section and an acid-adjusting extraction section, wherein the acid-adjusting extraction section is used to replenish acid during the extraction process to maintain a suitable acidity.

[0028] In some preferred embodiments, the extraction includes multi-stage countercurrent extraction, wherein the total number of stages in the multi-stage countercurrent extraction is 1 to 6.

[0029] Furthermore, the total number of stages in the multi-stage countercurrent extraction is 2 to 4 stages.

[0030] The multi-stage countercurrent extraction in this invention includes an extraction stage and an acid-adjusting extraction stage. The acid-adjusting extraction stage is used to supplement acid during the extraction process to maintain a suitable acidity. The total number of stages in the multi-stage countercurrent extraction is 1 to 6, preferably 2 to 4. The volumetric flow rate ratio of the extracted organic phase to the brine raw material (high boron solution) is preferably 0.5:1 to 3:1; the volumetric flow rate ratio of the brine raw material to the concentrated acid is preferably 1:1 to 50:1, more preferably 5:1 to 30:1. Increasing the flow rate ratio of the extracted organic phase to the brine raw material and increasing the number of extraction stages are both beneficial to improving the boron extraction effect. Appropriately reducing the flow rate ratio of the brine raw material to the concentrated acid (i.e., increasing the amount of acid used) can also improve the extraction rate. Those skilled in the art can comprehensively select the above parameters based on the actual needs of production costs and boron extraction effect.

[0031] In some preferred embodiments, the back-extraction agent used during the back-extraction is an aqueous solution of HCl or NaOH with a concentration of 0.01 to 1.0 mol / L, but is not limited thereto.

[0032] In some preferred embodiments, the ratio of the loaded organic phase to the stripping agent during back-extraction is 1:5 to 5:1.

[0033] In some preferred embodiments, the back-extraction includes multi-stage countercurrent back-extraction, wherein the total number of stages of the multi-stage countercurrent back-extraction is 1 to 6.

[0034] Furthermore, the total number of stages in the multi-stage countercurrent back-extraction is 2 to 4.

[0035] In some preferred embodiments, the volumetric flow rate ratio of the loaded organic phase to the stripping agent during back-extraction is 1:5 to 5:1.

[0036] In this invention, the total number of stages in the multi-stage countercurrent back-extraction is 1 to 6, preferably 2 to 4; the back-extraction ratio (the volumetric flow ratio of the extractant organic phase to the back-extractant aqueous solution) is preferably 0.5:1 to 5:1. Appropriately increasing the number of back-extraction stages and the ratio is beneficial to improving the back-extraction effect; using a smaller ratio allows for a higher concentration of boron in the back-extraction solution, and in this case, the back-extraction rate can be guaranteed by appropriately increasing the theoretical number of stages. Those skilled in the art can comprehensively select the above parameters based on the actual needs of production costs and back-extraction effect. The two phases undergo multi-stage countercurrent contact at a determined ratio, and a boron-rich back-extraction aqueous solution is obtained in the first stage of the back-extraction section. This solution can be concentrated by evaporation, cooled, and crystallized to obtain boric acid product; the organic phase discharged from the last stage can be recycled.

[0037] This invention integrates acidification and solvent extraction into the same operating unit, forming an acidification-extraction coupled process. High-concentration acid and organic matter are introduced together into the extraction section and mixed with boron-containing brine from a salt lake. While the brine is acidified to form boric acid, the boric acid is rapidly extracted into the organic phase in the mixing chamber or centrifugal extractor, resulting in a loaded organic phase and a boron-poor raffinate. This process prevents direct precipitation of boric acid while maintaining high extraction efficiency, thereby improving the overall boron yield. Based on this, corresponding extraction-back-extraction process conditions have been developed to achieve efficient recycling of the extractant. The process flow diagram of this invention is as follows: Figure 1 As shown.

[0038] Compared to the traditional "acidification-freeze crystallization + tail liquor extraction" process, this invention couples acidification conversion and solvent extraction into a single step, completely eliminating the steps of freeze crystallization, solid-liquid separation, and separate extraction of the mother liquor, thus significantly reducing the number of equipment and investment. Since it is no longer necessary to cool large quantities of brine to low temperatures, cooling energy consumption is reduced. Direct extraction can stably reduce the boron concentration in the raffinate to below 0.05 g / L, with a total boron recovery rate exceeding 99%. Simultaneously, the selectivity of the extraction process for boric acid ensures that impurities remain in the raffinate, and the back-extraction liquid can directly produce high-purity boric acid, guaranteeing product quality. The entire process is a continuous liquid-phase operation, easily scalable and automated, fundamentally eliminating the risk of crystallization blockage, and significantly enhancing adaptability to fluctuations in brine boron concentration and temperature changes.

[0039] 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.

[0040] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0041] Example 1 The raw material was the magnesium-containing brine from the Xitaijinaier salt lake in the Qaidam Basin of Qinghai Province after potassium extraction. The brine contained 37.10 g / L boric acid and the pH of the raw material was 4.60. A mixed solution of 50% isooctanol / 50% sulfonated kerosene was used as the organic phase for extraction. The extractant structure is shown in Table 1. The flow ratio of the organic phase to the feed liquid was 1:1. 0.05 mol / L HCl was used as the back-extraction agent, with a flow ratio of 1:1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 12.0 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 30:1. Three-stage countercurrent extraction (two-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction was obtained from the fourth stage. The boron concentration in the raffinate was measured to be 29 mg / L, and the boron extraction rate E% was calculated to be 99.55%. The boron (elemental boron) content in the back-extraction was measured to be 6.37 g / L, and the back-extraction efficiency reached 98.67%. The calculation method for the boron extraction rate E% is shown in the following formula: Extraction rate E% = ([c0v0 - c1v1] / [c0v0]) * 100 In the formula, E is the extraction rate, c0 is the boron concentration in the boric acid aqueous solution of the raw material (mol / L), c1 is the boron concentration in the boric acid aqueous solution of the raffinate (mol / L), v0 is the volume of the raw material solution (mL), and v1 is the volume of the raffinate (mL).

[0042] Table 1. Composition of the feed liquid and structure of the extractant

[0043] Example 2 The raw material was the magnesium-containing brine from the Xitaijinaier salt lake in the Qaidam Basin of Qinghai Province after potassium extraction. The brine contained 37.10 g / L boric acid and the pH of the raw material was 4.60. A mixed solution consisting of 80% isooctanol and 20% sulfonated kerosene was used as the organic phase for extraction. The extractant structure is shown in Table 2. The flow ratio of the organic phase to the feed liquid was 1 / 5. The back-extraction agent was 0.05 mol / L HCl, with a flow ratio of 2 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 6.0 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 12 / 1. Six-stage countercurrent extraction (four-stage extraction + two-stage acid-adjusting extraction) and four-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the seventh stage. The boron concentration in the raffinate was measured to be 45 mg / L, and the boron extraction rate (E%) was calculated to be 99.31%. The boron content in the back-extraction liquid was measured to be 2.57 g / L, and the back-extraction efficiency reached 99.75%.

[0044] Table 2. Composition of raw material liquid and structure of extractant

[0045] Example 3 The raw material was the magnesium-containing brine from the Xitaijinaier salt lake in the Qaidam Basin of Qinghai Province after potassium extraction. The brine contained 37.10 g / L boric acid and the pH of the raw material was 4.60. A mixed solution of 20% isooctanol / 90% sulfonated kerosene was used as the organic phase for extraction. The extractant structure is shown in Table 3. The flow ratio of the organic phase to the feed liquid was 5 / 1. The back-extraction agent was 0.02 mol / L HCl, with a flow ratio of 1 / 5 between the organic phase and the back-extraction agent. The concentration of concentrated H2SO4 was 0.5 mol / L, and the flow ratio of the old brine feed liquid to the concentrated H2SO4 was 1 / 1. Four-stage countercurrent extraction (three-stage extraction + one-stage acid-adjusting extraction) and four-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fifth stage. The boron concentration in the raffinate was measured to be 23 mg / L, and the boron extraction rate E% was calculated to be 99.65%. The boron content in the back-extraction liquid was measured to be 6.33 g / L, and the back-extraction efficiency reached 98.11%.

[0046] Table 3. Composition of raw material liquid and structure of extractant

[0047] Example 4 The raw material was the magnesium-containing brine from the old salt lake in Chaka Salt Lake in the Qaidam Basin of Qinghai Province after potassium extraction. The brine contained 12.37 g / L boric acid and the pH of the raw material was 4.72. A mixed solution of 10% 2-ethyl-1,3-hexanediol and 90% xylene was used as the organic phase for extraction. The extractant structure is shown in Table 4. The flow ratio of the organic phase to the feed liquid was 2 / 1. The back-extraction agent was 0.03 mol / L NaOH, with a flow ratio of 1 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 1 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 5 / 1. Three-stage countercurrent extraction (two-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fourth stage. The boron concentration in the raffinate was measured to be 6.2 mg / L, and the boron extraction rate (E%) was calculated to be 99.72%. The boron content in the back-extraction liquid was measured to be 1.05 g / L, and the back-extraction efficiency reached 98.11%.

[0048] Table 4. Composition of the feed liquid and structure of the extractant

[0049] Example 5 The feedstock was an old brine from the magnesium-containing salt lake in the Qarhan Basin of Qinghai Province, after potassium extraction. This brine contained 12.37 g / L boric acid, and the pH of the feedstock was 4.72. A mixed solution of 100% isooctanol was used as the organic phase for extraction. The extractant structure is shown in Table 5. The flow ratio of the organic phase to the feedstock was 1:1. The back-extraction agent was 0.05 mol / L HCl, with a flow ratio of 5:1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 10 mol / L, and the flow ratio of the old brine feedstock to the concentrated HCl was 24:1. Three-stage countercurrent extraction (two-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction was obtained from the fourth stage. The boron concentration in the raffinate was measured to be 12 mg / L, and the boron extraction rate (E%) was calculated to be 99.44%. The boron content in the back-extraction was measured to be 0.42 g / L, and the back-extraction efficiency reached 97.22%.

[0050] Table 5. Composition of raw material liquid and structure of extractant

[0051] Example 6 The raw material was an old brine from a magnesium-containing salt lake in Da Qaidam, Qaidam Basin, Qinghai Province, after potassium extraction. The brine contained 51.43 g / L boric acid and had a pH of 4.33. A mixed solution of 50% isooctanol / 50% sulfonated kerosene was used as the extraction organic phase. The extractant structure is shown in Table 6. The flow ratio of the extraction organic phase to the feed liquid was 2.5 / 1. The back-extraction agent was 0.01 mol / L HCl, with a flow ratio of 1.5 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 10 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 25 / 1. Four-stage countercurrent extraction (three-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fifth stage. The boron concentration in the raffinate was measured to be 16 mg / L, and the boron extraction rate E% was calculated to be 99.82%. The boron content in the back-extraction liquid was measured to be 5.38 g / L, and the back-extraction efficiency reached 98.40%.

[0052] Table 6. Composition of raw material liquid and structure of extractant

[0053] Example 7 The raw material was an old brine from a magnesium-containing salt lake in Da Qaidam, Qaidam Basin, Qinghai Province, after potassium extraction. The brine contained 51.43 g / L boric acid and had a pH of 4.33. A mixed solution consisting of 5% 2-ethyl-1,3-hexanediol / 45% isooctyl alcohol / 50% sulfonated kerosene was used as the extraction organic phase. The extractant structure is shown in Table 7. The flow ratio of the extraction organic phase to the feed liquid was 2 / 1. The back-extraction agent was 0.1 mol / L NaOH, with a flow ratio of 1.5 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 10 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 25 / 1. Three-stage countercurrent extraction (two-stage extraction + one-stage acid-adjusting extraction) and five-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fourth stage. The boron concentration in the raffinate was measured to be 13 mg / L, and the boron extraction rate E% was calculated to be 99.86%. The boron content in the back-extraction liquid was measured to be 6.80 g / L, and the back-extraction efficiency reached 99.02%.

[0054] Table 7. Composition of the feed liquid and structure of the extractant

[0055] Example 8 The raw material was the magnesium-containing brine from the Dongtaijinaier salt lake in the Qaidam Basin of Qinghai Province after potassium extraction. The brine contained 48.02 g / L boric acid and the pH of the raw material was 4.40. A mixed solution of 70% isooctanol / 30% sulfonated kerosene was used as the organic phase for extraction. The extractant structure is shown in Table 8. The flow ratio of the organic phase to the feed liquid was 2 / 1. The back-extraction agent was 0.05 mol / L HCl, with a flow ratio of 2 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 3 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 7 / 1. Four-stage countercurrent extraction (three-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fifth stage. The boron concentration in the raffinate was measured to be 9.6 mg / L, and the boron extraction rate E% was calculated to be 99.88%. The boron content in the back-extraction liquid was measured to be 8.24 g / L, and the back-extraction efficiency reached 98.89%.

[0056] Table 8. Composition of the feed liquid and structure of the extractant

[0057] Example 9 The raw material was the magnesium-containing brine from the old salt lake in Chaka Salt Lake in the Qaidam Basin of Qinghai Province after potassium extraction. The brine contained 5.20 g / L boric acid and the pH of the raw material was 5.73. A mixed solution consisting of 50% A1416 and 50% sulfonated kerosene was used as the organic phase for extraction. The extractant structure is shown in Table 9. The flow ratio of the organic phase to the feed liquid was 1 / 2. The back-extraction agent was 1.0 mol / L HCl, with a flow ratio of 1 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated H2SO4 was 18 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 50 / 1. Four-stage countercurrent extraction (three-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fifth stage. The boron concentration in the raffinate was measured to be 8.6 mg / L, and the boron extraction rate (E%) was calculated to be 99.06%. The boron content in the back-extraction liquid was measured to be 1.78 g / L, and the back-extraction efficiency reached 98.09%.

[0058] Table 9. Composition of the feed liquid and structure of the extractant

[0059] Comparative Example 1 The feed liquid was an old magnesium-containing salt lake brine from Dongtaijinaier in the Qaidam Basin of Qinghai Province, containing 48.02 g / L boric acid, with a pH of 4.40. A mixed solution of 70% isooctanol and 30% sulfonated kerosene was used as the organic phase for extraction. The extractant structure is shown in Table 10. The flow ratio of the organic phase to the feed liquid was 2:1. The back-extraction agent was 0.05 mol / L HCl, with a flow ratio of 1:1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 11.0 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 55:1. Four stages of countercurrent extraction (three stages of extraction + one stage of acid-adjusting extraction) and three stages of countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction was obtained from the fifth stage. The boron concentration in the raffinate was measured to be 972.9 mg / L, and the boron extraction rate (E%) was calculated to be only 88.42%.

[0060] Table 10. Composition of the feed liquid and structure of the extractant

[0061] Comparative Example 2 The feed liquid was old brine from the magnesium-containing salt lake after potassium extraction in Da Qaidam, Qaidam Basin, Qinghai Province. It contained 51.43 g / L boric acid, and the pH of the feed liquid was 4.33. A mixed solution of 50% isooctanol and 50% sulfonated kerosene was used as the extraction organic phase. The extractant structure is shown in Table 11. The flow ratio of the extraction organic phase to the feed liquid was 2.5 / 1. The back-extraction agent was 0.01 mol / L HCl, with a flow ratio of 7 / 1 between the organic phase and the back-extraction agent. The concentration of concentrated HCl was 10 mol / L, and the flow ratio of the old brine feed liquid to the concentrated HCl was 25 / 1. Four-stage countercurrent extraction (three-stage extraction + one-stage acid-adjusting extraction) and three-stage countercurrent back-extraction were performed at room temperature (25℃). Raffinate was obtained from the first stage, and boron-containing back-extraction liquid was obtained from the fifth stage. The boron content in the back-extraction liquid was measured to be 1.03 g / L, and the back-extraction efficiency was only 79.83%.

[0062] Table 11. Composition of the feed liquid and structure of the extractant

[0063] In addition, the applicant 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.

[0064] 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 boron from a high-boron solution using an acidification-extraction coupling process, characterized in that, include: High boron solution, concentrated acid, and extractant are simultaneously fed into the extraction unit for extraction and back-extraction, thereby achieving the separation and enrichment of boron. The concentration of H3BO3 in the high-boron solution is 1~55 g / L; the extraction organic phase includes an extractant and a diluent, and the extractant includes a monohydric fatty alcohol and / or a diol.

2. The method according to claim 1, characterized in that: The concentration of H3BO3 in the high boron solution is 5~55 g / L; And / or, the concentration of magnesium ions in the high boron solution is 20–200 g / L; And / or, the pH value of the high boron solution is 0 to 8; And / or, the high-boron solution includes any one or more combinations of salt lake brine, underground brine, and boron ore leaching solution.

3. The method according to claim 1, characterized in that: The monohydric fatty alcohols include monohydric fatty alcohols containing 6 to 16 carbon atoms; And / or, the extractant comprises any one or more combinations of isooctanol, 2-ethylhexanol, n-octanol, n-dodecanol, isododecanol, n-tetradecanool, isotetradecanool, n-hexadecylol, isohexadecylol, 2-ethyl-1,3-hexanediol, and 2,2,4-trimethyl-1,3-pentanediol; And / or, the diluent comprises any one or more combinations of kerosene, sulfonated kerosene, aviation kerosene, benzene, xylene, carbon tetrachloride, heptanol, o-dichlorobenzene, trichlorobenzene, heptane, n-dodecane, decanol, diisobutyl ketone, 1,2-dichloroethane, butyl acetate, amyl acetate, and ionic liquids with low water solubility; preferably, the ionic liquid comprises any one or more combinations of imidazole ionic liquids, pyridine ionic liquids, quaternary ammonium salt ionic liquids, and quaternary phosphonium salt ionic liquids, wherein the imidazole ionic liquid comprises [BMIM][PF6] and / or [EMIM][Tf2N]; And / or, the volume fraction of the extractant in the extracted organic phase is 10% to 100%.

4. The method according to claim 1, characterized in that: The concentrated acid includes any one or more combinations of concentrated hydrochloric acid, concentrated sulfuric acid, and concentrated nitric acid. And / or, the concentrated acid contains H + The concentration ranges from 0.5 to 18.5 mol / L.

5. The method according to claim 1, characterized in that: The volume ratio of the extracted organic phase to the high boron solution is 1:5 to 5:

1. And / or, the extraction and back-extraction temperatures are each independently between 10°C and 40°C.

6. The method according to claim 1, characterized in that: The volume flow ratio of the extracted organic phase to the high boron solution is 1:5 to 5:1; And / or, the volume flow ratio of the high boron solution to the concentrated acid is 1:1 to 50:1, preferably 5:1 to 30:

1.

7. The method according to claim 1, characterized in that: The extraction unit includes an extraction section and an acid-adjusting extraction section, wherein the acid-adjusting extraction section is used to supplement acid during the extraction process to maintain a suitable acidity.

8. The method according to claim 1, characterized in that: The extraction includes multi-stage countercurrent extraction, wherein the total number of stages of the multi-stage countercurrent extraction is 1 to 6, preferably 2 to 4.

9. The method according to claim 1, characterized in that: The stripping agent used in the stripping process is an aqueous solution of HCl or NaOH with a concentration of 0.01–1.0 mol / L; And / or, the ratio of the loaded organic phase to the stripping agent during the back-extraction is 1:5 to 5:

1.

10. The method according to claim 1, characterized in that: The back-extraction includes multi-stage countercurrent back-extraction, and the total number of stages of the multi-stage countercurrent back-extraction is 1 to 6 stages, preferably 2 to 4 stages; And / or, the volumetric flow rate ratio of the loaded organic phase to the stripping agent during the back-extraction is 1:5 to 5:1.

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