Method for extracting rubidium carbonate from rubidium-containing brine

Abstract

The invention discloses a method for extracting rubidium carbonate from rubidium-containing brine, which comprises the following steps: firstly, removing potassium in the rubidium-containing brine by adopting aluminum sulfate in two steps, controlling the ratio of Rb to K to be 13.5 or above, secondly, adding tartaric acid with low solute molar concentration in the step S3, and complexing the rest trace K element to form water-soluble potassium tartrate macromolecules, so that Rb and K are effectively separated; rubidium carbonate with the purity of 99.9% or above can be formed at a low extraction stage in subsequent extraction, so that compared with the prior art, in the aspect of extracting high-purity rubidium carbonate (greater than or equal to 99.9%), the dosage of the extracting agent T-BAMBP is greatly reduced, the whole process is simple in step and easy to popularize, and in some preferred embodiments, the yield of the rubidium carbonate is greatly increased. The rubidium loss can be reduced by controlling the solute molar concentration of aluminum sulfate.

Description

Technical Field

[0001] The invention relates to the technical field of alkali metal element extraction, and in particular to a method for extracting rubidium carbonate from rubidium-containing brine. Background Art

[0002] At present, rubidium is one of the rare metal elements that occupies a strategic position. It has shown broad application prospects and market demand in high-tech fields such as national defense industry, aerospace industry, bioengineering, medicine and energy industry. In particular, as a component of solid-state lasers, photovoltaic cells, phosphors, fuel cell electrolytes and other materials, its application in the energy field has great potential and has become a key metal resource in the guiding frontier fields in the development of emerging industries.

[0003] However, rubidium is a rare metal resource with a low content in the earth's crust and a complex occurrence state, making it difficult to extract and develop. In terms of element abundance in the earth's crust, the abundance of Rb is 30 times that of Cs and 4 times that of Li, but it is often used as a by-product of the extraction of these two metals. There are few independent minerals, and even fewer independent deposits. It is mainly distributed in brine or silicate ores. + Usually with other metal elements (Li + 、Na + , K + Mg 2+ , Ca 2+ ) coexistence, coupled with lower grade, especially with Rb + K with similar physical and chemical properties + It is difficult to achieve effective separation using traditional methods, which is one of the important factors that make it difficult to produce rubidium salts with nearly 100% extraction purity in existing technologies.

[0004] In the prior art, Chinese application CN116477645A discloses a low-cost simplified process for preparing two products, a high-purity cesium salt and a high-purity rubidium salt. A purified rubidium-cesium salt solution is obtained by removing potassium and aluminum from a mixed solution containing rubidium, cesium and potassium. The potassium removal method is to add tartaric acid to the mixed solution containing rubidium, cesium and potassium to form rubidium-cesium salt crystals with a potassium content of less than 0.0035%. After aluminum removal, cesium extraction and rubidium extraction are performed. In this scheme, although the potassium removal method of adding tartaric acid to form rubidium-cesium salt crystals has a low K content, a large amount of tartaric acid reagent is required to form rubidium-cesium salt crystals, and the reagent cost is relatively high.

[0005] Based on the state of the art, it has been recognized that an improved method for extracting rubidium carbonate is needed, which can effectively separate K and Rb during the extraction of high-purity rubidium carbonate, simplify the process steps, and reduce the cost of reagents. Summary of the invention

[0006] The main purpose of the present invention is to provide a method for extracting rubidium carbonate from rubidium-containing brine, which can effectively separate K and Rb in the process of extracting high-purity rubidium carbonate, simplify the process steps, and reduce the reagent cost, aiming to solve the technical problems of complex process steps and high reagent cost in the extraction process of rubidium salt with extraction purity close to 100% in the prior art.

[0007] To achieve the above object, the present invention provides a method for extracting rubidium carbonate from rubidium-containing brine, comprising the following steps:

[0008] S1. Removing potassium from rubidium-containing brine by a two-step aluminum sulfate method. The two-step aluminum sulfate method first forms a mixed alum by adding aluminum sulfate to the rubidium-containing brine, so that the molar ratio of Rb:K in the mixed alum is a, 0.5≤a≤3.8; then the mixed alum is dissolved in water to obtain a primary potassium removal solution, and then aluminum sulfate is added to form a secondary potassium removal mixed alum precipitate, so that the molar ratio of Rb:K in the secondary potassium removal mixed alum is b, 13.5≤b≤21.2.

[0009] S2, taking a secondary potassium removal mixed alum and dissolving it in water to obtain a secondary potassium removal solution, and then removing aluminum to obtain a potassium and aluminum removal solution;

[0010] S3, removing the potassium aluminum solution, adding tartaric acid to form a tartaric acid solution with a solute molar concentration of A, 0.05mol / L≤A<0.20mol / L, and the tartaric acid solution reacts with potassium ions to form a water-soluble potassium tartrate macromolecule;

[0011] S4, taking the potassium-aluminum-removed solution obtained in S3, extracting and separating rubidium with T-BAMBP as an extractant, and sulfonated kerosene and xylene as diluents, dissolving oxalic acid with a purity of more than 99.0% in high-purity water to prepare a stripping acid for stripping to obtain a stripping solution containing rubidium oxalate, and performing multi-stage extraction, washing, and stripping until the rubidium oxalate in the stripping solution reaches the target purity requirement;

[0012] S5. Add excess oxalic acid to the stripping solution obtained in S4, cool and crystallize, centrifuge to obtain rubidium oxalate crystals, and calcine in an oxidizing atmosphere to obtain rubidium carbonate powder.

[0013] In the present invention, in terms of potassium removal, firstly, aluminum sulfate is used in two steps to remove potassium from rubidium-containing brine, and the molar ratio of Rb:K is controlled at 13.5-21.2. Secondly, tartaric acid with a lower solute molar concentration is added in step S3 to complex the remaining trace potassium to form a water-soluble potassium tartrate macromolecule. Due to the low molar concentration of the tartaric acid solute, rubidium tartrate and cesium tartrate precipitate crystals are not formed in the solution (if precipitate crystals need to be formed, the molar concentration of the tartaric acid solute must usually reach 0.23 mol / L or more). In the subsequent extraction process of the present invention, potassium tartrate is concentrated in the solution. The molecules will not be extracted into the organic phase, but will be retained in the aqueous phase, so that Rb and K in the rubidium-containing brine are effectively separated. In the early stage, the present invention uses aluminum sulfate to remove potassium in two steps, thereby increasing the amount of low-cost aluminum sulfate. However, the cost of aluminum sulfate is currently only about 1 / 10 of the cost of tartaric acid, and its source is wide. In the prior art, medium-to-high concentration tartaric acid solutions are used to form rubidium tartrate and cesium tartrate crystals, and the crystals are dissolved to obtain a rubidium-cesium solution with an extremely low potassium ion concentration. Compared with the prior art, the present invention saves 50% to 85% of the reagent cost in removing potassium.

[0014] Since the present invention enables Rb and K to be effectively separated, rubidium carbonate with a purity of 99.9% or more can be formed at a lower extraction level in the subsequent extraction-stripping process, thereby greatly reducing the amount of the extractant T-BAMBP used compared with the prior art. The extractant T-BAMBP is expensive. The use of the present invention to extract high-purity rubidium carbonate (≥99.9%) can greatly save reagent costs, and the overall process steps are simple and easy to promote.

[0015] High-purity water is a term in the industry, referring to water with a conductivity of less than 0.1μs / cm and a residual salt content of less than 0.3mg / L at 25°C, and water from which non-dielectric impurities such as trace bacteria, microorganisms, and particles have been removed.

[0016] Preferably, the aluminum sulfate added in S1 forms an aluminum sulfate solution with a solute molar concentration of B in the rubidium-containing brine and the primary potassium removal solution, and 0.35 mol / L≤B≤0.55 mol / L.

[0017] Aluminum sulfate at this solute molar concentration is conducive to precipitating more than 90% of rubidium each time a mixed alum is formed.

[0018] Further preferably, A is 0.1 mol / L and B is 0.4 mol / L. The technical effect under this parameter is optimal. When extracting rubidium carbonate with a purity of more than 99.9%, the extraction stage is 17, and the mass of rubidium carbonate reaches 74.8% of the mass of the raw material. When extracting rubidium carbonate with a purity of more than 99.99%, the extraction stage is 26, and the mass of rubidium carbonate reaches 65.2% of the mass of the raw material.

[0019] Preferably, the aluminum removal step in S3 is: introducing a gas containing CO2 into the secondary potassium removal solution, adjusting the pH to 6.5-7.5 to form aluminum oxide precipitation, and filtering to obtain a potassium and aluminum removal solution. More preferably, the pH is 7. This method can effectively remove aluminum without generating new impurities that are difficult to remove.

[0020] Preferably, the rubidium content in the rubidium-containing brine is ≥5g / L. The rubidium-containing brine with this rubidium content can better reflect the effect of effectively separating Rb and K in the present invention, reducing the number of extraction stages, and saving reagent costs. When the rubidium content in the rubidium-containing brine is low, the molar ratio of Rb:K in step S1 of the present invention will be difficult to meet the corresponding requirements. Those skilled in the art can increase the rubidium content in the rubidium-containing brine by concentration, and then use the present invention to extract rubidium. The source of the rubidium-containing brine in the scheme is mainly the concentrated solution of the leaching solution of the rubidium-containing ore. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in this field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] The present invention is further described below by way of examples. Raw materials, reagents, etc. not specifically described are all commercially available, and the same batch of raw materials or reagents are used in both the examples and comparative examples.

[0023] The raw materials used in the following examples and comparative examples are mainly rubidium-containing brine (concentrated mother liquor).

[0024] The element content analysis of rubidium-containing brine (concentrated mother liquor) is as follows:

[0025] R K Li Na Content (g / L) 21.5 22.1 5.9 3.1

[0026] The specific values ​​of the solute molar concentration A of tartaric acid in S3 and the solute molar concentration B of aluminum sulfate in S1 in the methods of extracting rubidium carbonate from rubidium-containing brine of Examples 1 to 3 and Comparative Examples 1 to 3 are shown in Table 1.

[0027] Table 1

[0028]

[0029] Examples 1 to 3 refer to the following preparation items:

[0030] A method for extracting rubidium carbonate from rubidium-containing brine comprises the following steps:

[0031] S1. Aluminum sulfate is added to 200 ml of rubidium-containing brine to form a mixed alum, wherein the molar ratio of Rb:K in the mixed alum is a; the mixed alum is dissolved in water to obtain a primary potassium removal solution, and aluminum sulfate is added to form a secondary potassium removal mixed alum, wherein the molar ratio of Rb:K in the secondary potassium removal mixed alum is b;

[0032] The aluminum sulfate added in S1 forms an aluminum sulfate solution with a solute molar concentration of B in the rubidium-containing brine and the primary potassium removal solution;

[0033] S2, taking the secondary potassium removal mixed alum and dissolving it in water to obtain a secondary potassium removal solution, and then removing aluminum to obtain a potassium removal aluminum solution; the aluminum removal step is: passing a gas containing CO2 into the secondary potassium removal solution, adjusting the pH to 7 to form an aluminum oxide precipitate, and filtering to obtain a potassium removal aluminum solution;

[0034] S3, adding tartaric acid to the potassium-aluminum removal solution, the tartaric acid forms a tartaric acid solution with a solute molar concentration of A in the potassium-aluminum removal solution, and the complex potassium forms a water-soluble potassium tartrate macromolecule;

[0035] S4, taking the potassium-aluminum-removed solution obtained in S3, extracting and separating rubidium with T-BAMBP as an extractant, sulfonated kerosene and xylene as diluents, dissolving oxalic acid with a purity of more than 99.0% in high-purity water to prepare a stripping acid for stripping to obtain a stripping solution containing rubidium oxalate, and performing multi-stage extraction, washing, and stripping until the rubidium oxalate in the stripping solution reaches the target purity requirement;

[0036] S5, adding excess oxalic acid to the stripping solution obtained in S4, cooling and crystallizing, centrifuging to obtain rubidium oxalate crystals, and then calcining to obtain high-purity rubidium carbonate powder;

[0037] The calcination conditions are as follows: the temperature is gradually increased from 0°C to 600°C within 60 minutes under continuous air flow, and the calcination is continued at 600°C for 120 minutes. The air flow rate is 400 sccm.

[0038] Comparative Example 1

[0039] A method for extracting rubidium carbonate from rubidium-containing brine comprises the following steps:

[0040] S1. Add 53.3 g of aluminum sulfate from 200 ml of rubidium-containing brine to form an aluminum sulfate solution with a solute molar concentration of B in the rubidium-containing brine, and precipitate to form mixed alum;

[0041] S2, dissolving the mixed alum in water, adding tartaric acid, the tartaric acid forms a tartaric acid solution with a solute molar concentration of A in the potassium-aluminum removal solution, and precipitates to form rubidium tartrate and cesium tartrate crystals;

[0042] S3, dissolving the crystals obtained in S2 with water, and then removing aluminum to obtain a potassium-aluminum-removed solution; the aluminum removal step is: introducing air or CO2 into the secondary potassium-removed solution, adjusting the pH to 7 to form aluminum oxide precipitation, and accurately filtering to obtain a potassium-aluminum-removed solution;

[0043] S4-S5 refer to the steps corresponding to S4-S5 in the preparation items of the aforementioned Examples 1-3, and finally obtain high-purity rubidium carbonate powder.

[0044] Comparative Example 2

[0045] The preparation steps are as described in Example 1-2, with the specific adjustment being that the operation of adding tartaric acid in step S3 is not performed.

[0046] Comparative Example 3

[0047] The preparation steps are as shown in Example 1-2, with the following specific adjustments:

[0048] Step S1 is adjusted as follows: 53.3 g of aluminum sulfate is added to 200 ml of rubidium-containing brine to form an aluminum sulfate solution with a solute molar concentration of B in the rubidium-containing brine, and mixed alum is precipitated;

[0049] Step S2 is adjusted as follows: adding water to the mixed alum to dissolve and then removing aluminum to obtain a potassium-aluminum-removed solution; the aluminum removal step is as follows: introducing a gas containing CO2 into the secondary potassium-removed solution, adjusting the pH to 7 to form an aluminum oxide precipitate, and filtering to obtain a potassium-aluminum-removed solution.

[0050] The molar ratio of Rb:K in step S1 in the examples and comparative examples was detected to obtain the mass of rubidium carbonate with a purity of 99.9% and above 99.99%, as well as the conversion rate and extraction level relative to the mass of the raw material.

[0051]

[0052]

[0053] From the above data, we can conclude that:

[0054] It can be seen from the data of Examples 1-1 to 1-3 relative to Comparative Example 1 that the method of the present application significantly reduces the number of extraction stages by 5 to 9 when preparing and extracting high-purity (≥99.9%) rubidium carbonate, thereby greatly reducing the amount of the extractant T-BAMBP used, and by comparing Examples 1-2 with Comparative Example 1, it can be seen that the mass of the obtained rubidium carbonate is significantly increased by more than 2 times. Analysis may be due to the low precipitation rate and large rubidium loss when the prior art uses a tartaric acid solution with a medium to high solute molar concentration to precipitate rubidium tartrate crystals. From the comparison between Example 1-2 and Example 2-1 to 2-3, it can be seen that when the two-step aluminum sulfate method is used to control the degree of potassium removal and low solute molar concentration tartaric acid is added before extraction to complex the remaining potassium ions, and the solute molar concentration of the aluminum sulfate solution is greater than 0.3 mol / L, it is beneficial to significantly improve the quality of the obtained rubidium carbonate. When the solute molar concentration of the aluminum sulfate solution is 0.6 mol / L, the quality of the obtained rubidium carbonate is significantly improved, but at the same time, more potassium is precipitated, so that the subsequent extraction level is improved. The solute molar concentration of the aluminum sulfate solution is preferably limited to the range of 0.35 to 0.55 mol / L, which is helpful to precipitate most of the rubidium when forming a mixed alum, and is beneficial to cooperate with the step of adding low solute molar concentration tartaric acid before subsequent extraction to obtain a good rubidium potassium separation effect.

[0055] From the comparison of Examples 1-2 and Comparative Examples 2 to 3, it can be seen that in Comparative Example 2, low solute molar concentration tartaric acid is not added before extraction. Due to the presence of a small amount of potassium impurities, the subsequent extraction of 99.9% or more purity rubidium carbonate is significantly improved. In Comparative Example 3, since the two-step aluminum sulfate method is not used in S1 to control the degree of potassium removal, only the addition of low solute molar concentration tartaric acid before extraction cannot effectively separate potassium and rubidium. Even if the extraction level is increased, high-purity rubidium carbonate of more than 99.9% cannot be obtained, indicating that it is necessary to use two-step aluminum sulfate to control the degree of potassium removal and add low solute molar concentration tartaric acid before extraction to complex the remaining trace potassium in order to effectively separate potassium and rubidium, and significantly reduce the extraction level when extracting rubidium carbonate with a purity of more than 99.9%.

[0056] Embodiment 3 has the best effect. When rubidium carbonate with a purity of more than 99.9% is extracted, the extraction stage is 17, and the mass of rubidium carbonate reaches 74.8% of the mass of the raw material. When rubidium carbonate with a purity of more than 99.99% is extracted, the extraction stage is 26, and the mass of rubidium carbonate reaches 65.2% of the mass of the raw material. It is the most preferred embodiment.

[0057] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for extracting rubidium carbonate from rubidium-containing brine, characterized in that: The following steps are involved: S1. Removing potassium from rubidium-containing brine by a two-step aluminum sulfate method. The two-step aluminum sulfate method first forms a mixed alum by adding aluminum sulfate to the rubidium-containing brine, so that the molar ratio of Rb:K in the mixed alum is a, 0.5≤a≤3.8; then the mixed alum is dissolved in water to obtain a primary potassium removal solution, and then aluminum sulfate is added to form a secondary potassium removal mixed alum precipitate, so that the molar ratio of Rb:K in the secondary potassium removal mixed alum is b, 13.5≤b≤21.

2. S2, taking the secondary potassium removal mixed alum and dissolving it in water to obtain a secondary potassium removal solution, and then removing aluminum to obtain a potassium and aluminum removal solution; S3, taking the potassium-aluminum removal solution, adding tartaric acid to form a tartaric acid solution with a solute molar concentration of A, 0.05 mol / L≤A<0.20 mol / L, and the tartaric acid solution reacts with potassium ions to form potassium tartrate; S4, taking the potassium-aluminum-removed solution obtained in S3, extracting and separating rubidium with T-BAMBP as an extractant, sulfonated kerosene and xylene as diluents, dissolving oxalic acid with a purity of more than 99.0% in high-purity water to prepare a stripping acid for stripping to obtain a stripping solution containing rubidium oxalate, and performing multi-stage extraction, washing, and stripping until the rubidium oxalate in the stripping solution reaches the target purity requirement; S5. Add excess oxalic acid to the stripping solution obtained in S4, cool and crystallize, centrifuge to obtain rubidium oxalate crystals, and calcine in an oxidizing atmosphere to obtain rubidium carbonate powder.

2. The method for extracting rubidium carbonate from rubidium-containing brine as claimed in claim 1, characterized in that: The aluminum sulfate added in S1 forms an aluminum sulfate solution with a solute molar concentration of B in the rubidium-containing brine and the primary potassium removal solution, and 0.35 mol / L≤B≤0.55 mol / L.

3. The method for extracting rubidium carbonate from rubidium-containing brine as claimed in claim 2, characterized in that: The A is 0.1 mol / L, and the B is 0.4 mol / L.

4. The method for extracting rubidium carbonate from rubidium-containing brine as claimed in claim 1, characterized in that: The aluminum removal step in S3 is: introducing a gas containing CO2 into the secondary potassium removal solution, adjusting the pH to 6.5-7.5 to form aluminum oxide precipitation, and filtering to obtain the potassium-aluminum removal solution.

5. The method for extracting rubidium carbonate from rubidium-containing brine as claimed in claim 1, characterized in that: The rubidium content in the rubidium-containing brine is ≥5g / L.

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