Method for preparing high-purity cesium carbonate from frozen mixed salt
The method for preparing high-purity cesium carbonate by freezing mixed salts and utilizing the selective separation and recycling of alcohol substances solves the problems of low cesium extraction efficiency and insufficient purity in the existing technology, and realizes efficient and low-cost cesium extraction and purification.
Patent Information
- Application Number
- CN202511024906.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-24
- Publication Date
- 2025-10-10
AI Technical Summary
Existing methods for extracting cesium from lepidolite mixed salts are inefficient and costly, and potassium and sodium impurities affect the quality of the cesium product and the difficulty of extraction, resulting in large amounts of cesium loss.
A method for preparing high-purity cesium carbonate by using frozen mixed salt includes the steps of drying, mixing with alcohols, solid-liquid separation, hydrolysis, distillation, carbonization and drying. The multi-stage extraction step is avoided through the selective separation and recycling of alcohols.
The cesium yield was increased to 80% to 95%, the purity of cesium carbonate products reached over 99.9%, the production energy consumption was reduced by over 30%, and the production cycle was shortened.
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of nonferrous metal processing, and in particular to a method for preparing high-purity cesium carbonate from lepidolite mixed salt. Background Art
[0002] As energy issues become increasingly prominent, the research and development and industrialization of new energy materials such as lithium-ion batteries are booming. my country has abundant lepidolite mineral resources, and the extraction of metals such as lithium, rubidium, and cesium from lepidolite raw materials has good development prospects. However, the cesium content in lepidolite raw materials is approximately 0.17%, while the potassium and sodium contents are as high as 6.5% and 1.25% respectively. Due to the extremely high solubility of potassium and sodium salts in water, these impurities will not only reduce the quality of the cesium product, but also make the extraction of cesium salts more difficult and increase the extraction cost. The existing recovery process mainly extracts rubidium and cesium from mixed solutions. The extraction effect of higher concentrations of potassium and sodium mixed solutions is not ideal, resulting in a large loss of cesium, low production efficiency, and high energy consumption. Summary of the Invention
[0003] The present application provides a method for preparing high-purity cesium carbonate from lepidolite mixed salt, which is conducive to achieving efficient extraction and purification of cesium.
[0004] In a first aspect, an embodiment of the present application provides a method for preparing high-purity cesium carbonate from a frozen mixed salt, comprising:
[0005] Drying the frozen mixed salt;
[0006] mixing the dried frozen mixed salt and the alcohol substance in a predetermined ratio and stirring to obtain a mixture;
[0007] performing solid-liquid separation on the mixture to obtain a cesium-containing solution and a solid residue containing potassium and sodium salts;
[0008] adding water to the cesium-containing solution for hydrolysis to form a solvent-water mixed phase;
[0009] Separating and recovering the solvent from the solvent-water mixed phase by distillation or fractional distillation to obtain a cesium hydroxide solution;
[0010] performing carbonization treatment on the cesium hydroxide solution to generate a cesium carbonate solution;
[0011] Concentrating the cesium carbonate solution to a set solid-liquid ratio and then performing solid-liquid separation to obtain wet cesium carbonate and a filtrate;
[0012] The wet cesium carbonate is dried to obtain a cesium carbonate product.
[0013] According to the first aspect, in a possible implementation manner, the alcohol compound is one or more of methanol, ethanol or propanol.
[0014] According to the first aspect, in one possible implementation, in the step of mixing and stirring the dried frozen mixed salt and the alcohol substance in a preset proportion to obtain a mixture:
[0015] The mass ratio of the anhydrous mixed salt to the alcohol substance is 5-1.
[0016] According to the first aspect, in one possible implementation, in the step of adding water to the cesium-containing solution for hydrolysis to form a solvent-water mixed phase:
[0017] The mass ratio of the cesium-containing solution to water is 10 to 0.5.
[0018] According to the first aspect, in a possible implementation, the cesium hydroxide solution is carbonized to generate a cesium carbonate solution:
[0019] Carbon dioxide is added to the cesium hydroxide solution to achieve carbonization treatment.
[0020] According to the first aspect, in one possible implementation, in the step of concentrating the cesium carbonate solution to a set solid-liquid ratio and then performing solid-liquid separation to obtain wet cesium carbonate and a filtrate:
[0021] The concentrated solid-liquid ratio is 50%-70%.
[0022] According to the first aspect, in a possible implementation, in the step of drying the wet cesium carbonate to obtain a cesium carbonate product, the drying temperature is 180°C to 320°C.
[0023] According to the first aspect, in a possible implementation, the step of carbonizing the cesium hydroxide solution to generate the cesium carbonate solution further includes:
[0024] The filtrate is mixed with the cesium hydroxide solution and then carbonized to generate a cesium carbonate solution.
[0025] The method provided in this application for preparing high-purity cesium carbonate from frozen mixed salts increases the cesium yield to 80% to 95% through the selective separation of alcohol substances, and the purity of the cesium carbonate product reaches above 99.9%. It also avoids multi-stage extraction steps, shortens the production cycle, and reduces energy consumption by more than 30%. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the implementation methods or the description of the prior art. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0027] Figure 1 The present invention is a schematic diagram of a method for preparing high-purity cesium carbonate from a lepidolite mixed salt according to an embodiment. DETAILED DESCRIPTION
[0028] The terms "preferably," "more preferably," and the like, used herein refer to embodiments of the present invention that may provide certain benefits under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the present invention.
[0029] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.
[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts are within the scope of the present invention.
[0031] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.
[0032] The present application provides a method for preparing high-purity cesium carbonate from frozen mixed salts, such as Figure 1 As shown, the method for preparing high-purity cesium carbonate from frozen mixed salt comprises the following steps:
[0033] Step S10, drying the frozen mixed salt;
[0034] The moisture in the frozen mixed salt can be effectively removed by drying.
[0035] In step S10, the drying temperature is crucial when drying the frozen salt mixture. To ensure effective removal of moisture from the salt mixture while preventing decomposition or deterioration of its useful components, the drying temperature is typically controlled between several tens of degrees Celsius and over 100 degrees Celsius. The specific temperature is adjusted based on the physical and chemical properties of the salt mixture and the desired degree of dryness.
[0036] The selection of drying equipment is also crucial. Common drying equipment includes ovens, belt dryers, vacuum dryers, and fluidized bed dryers. When selecting drying equipment, factors such as the properties of the salt mixture, production scale, budget, and ease of maintenance and operation should be considered. By properly selecting and controlling the drying temperature and drying equipment, the salt mixture can be fully dried, providing high-quality raw materials for subsequent steps.
[0037] Step S20: mixing the dried frozen mixed salt and the alcohol substance in a preset ratio and stirring to obtain a mixture;
[0038] The frozen mixed salts that have been dried are mixed with selected alcohols. The alcohols can be a mixture of one or more of methanol, ethanol or propanol. The selection of these alcohols is usually based on factors such as their reactivity, cost-effectiveness and environmental impact.
[0039] Mixing must be done according to a preset ratio: the mass ratio of anhydrous mixed salt to alcohol is controlled within a range of 5 to 1. This ratio is chosen to ensure uniform mixing while allowing the reaction to proceed efficiently and controllably. If the alcohol content is too high, the reaction may be too vigorous and difficult to control; if the content is too low, the reaction may be incomplete, affecting the purity and yield of the final product.
[0040] During the mixing process, a specific chemical reaction will occur. Here A represents alcohol, and its reaction can be expressed as: ACOOH+Na + =ACOONa+H + It is important to note that this reaction equation is intended to illustrate the type of chemical reaction that may occur during mixing, and the actual reaction may vary depending on the specific type of alcohol and the composition of the mixed salts.
[0041] After mixing is completed, sufficient stirring is required to ensure that the mixed salt and alcohol substances are fully in contact and evenly dispersed. The stirring time and speed should be adjusted according to the specific situation to achieve the best mixing effect and reaction efficiency.
[0042] Step S30, performing solid-liquid separation on the mixture to obtain a cesium-containing solution and a solid residue containing potassium and sodium salts;
[0043] In step S30, solid-liquid separation can generally be achieved by methods such as filtration, centrifugation, or gravity sedimentation. The choice of these methods depends on the specific properties of the mixture, such as particle size, density, viscosity, etc., as well as the requirements for separation efficiency and cost. In actual operation, it is necessary to select an appropriate method based on the specific properties of the mixture and the separation requirements. At the same time, in order to ensure the separation effect, it may be necessary to further process the cesium-containing solution and solid residue after separation, such as washing, drying, etc.
[0044] The solid-liquid separation process in step S30 produces a relatively pure cesium solution and a solid residue containing potassium and sodium salts. The cesium solution is used in subsequent extraction and purification steps to produce high-purity cesium, while the solid residue containing potassium and sodium salts can be recovered or processed as a byproduct.
[0045] Step S40, adding water to the cesium-containing solution for hydrolysis to form a solvent-water mixed phase;
[0046] A certain amount of water is added to the cesium solution. The mass ratio of cesium solution to water can be controlled within a range of 10 to 0.5. The specific ratio depends on the concentration of the cesium solution, the desired degree of hydrolysis, and the requirements of subsequent processing steps. By adjusting this ratio, the hydrolysis reaction can be carried out efficiently and in a controlled manner.
[0047] Its hydrolysis reaction can be expressed as: ACOONa+H2O=ACOOH+OH - .
[0048] Step S50, separating and recovering the solvent from the solvent-water mixed phase by distillation or fractionation to obtain a cesium hydroxide solution;
[0049] By utilizing the boiling point difference between alcohol and water, alcohols are distilled and purified from the mixed solution for reuse, achieving efficient resource utilization and cost reduction. During the separation and recovery of alcohols, cesium hydroxide remains in the aqueous phase due to the removal of the alcohols, forming a cesium hydroxide solution.
[0050] Step S60, carbonizing the cesium hydroxide solution to generate a cesium carbonate solution;
[0051] In short, carbonization involves introducing carbon dioxide gas into a solution containing hydroxides, utilizing the chemical properties of carbon dioxide to react with the hydroxides to produce the corresponding carbonates. In this step, the cesium hydroxide solution is the main component of the reaction, while carbon dioxide is introduced as the carbonizing agent.
[0052] Carbon dioxide gas is introduced into the cesium hydroxide solution at an appropriate flow rate and pressure. During this process, carbon dioxide and cesium hydroxide undergo the following chemical reaction: 2CsOH + CO2 = Cs2CO3 + H2O.
[0053] Step S70, concentrating the cesium carbonate solution to a set solid-liquid ratio and then separating the solid and the liquid to obtain wet cesium carbonate and a filtrate;
[0054] The cesium carbonate solution is concentrated to a desired solid-to-liquid ratio, typically 50% to 70%. This means that the solute (cesium carbonate) content in the solution increases while the solvent (water) content decreases. Concentration can be achieved by evaporation, distillation, or membrane concentration, depending on process conditions and economics.
[0055] The concentrated solution is then subjected to solid-liquid separation to obtain wet cesium carbonate and a filtrate. Solid-liquid separation can be performed by filtration, centrifugation, or sedimentation. Wet cesium carbonate is solid cesium carbonate containing a certain amount of water, while the filtrate is the separated liquid portion.
[0056] The obtained filtrate is mainly a sodium carbonate solution. This may be because in the previous steps (such as the carbonization treatment in step S60), in addition to generating cesium carbonate, sodium carbonate may also be generated as a by-product in the reaction system.
[0057] The filtrate obtained in step S70 is returned to step S60, mixed with the cesium hydroxide solution, and then carbonized to produce more cesium carbonate solution. This recycling strategy helps improve raw material utilization and reduce production costs. It also embodies the concept of a circular economy, which aims to minimize waste generation and maximize the value of resources.
[0058] Step S80: drying the wet cesium carbonate to obtain a cesium carbonate product.
[0059] In step S80, the drying process is typically performed by heating. Heating can accelerate the evaporation of water, thereby shortening the drying time and improving the drying efficiency. However, the selection of the heating temperature is crucial, as excessively high temperatures may cause the cesium carbonate to decompose or deteriorate.
[0060] The drying temperature is typically between 180°C and 320°C. This temperature range is determined based on the thermal stability of cesium carbonate and the rate of water evaporation. Within this temperature range, water can be effectively evaporated from the wet cesium carbonate while maintaining its chemical properties without decomposition or deterioration.
[0061] After drying, the moisture in the wet cesium carbonate is removed to obtain a pure, dry cesium carbonate product.
[0062] The cesium source in this application is the frozen mixed salt produced by the MVR freezing line. The frozen mixed salt contains 64% potassium sulfate and about 34% sodium sulfate, while the cesium content is only 0.11%. Conventional solution extraction method cannot extract and prepare high-purity cesium carbonate products from this mixed salt.
[0063] And the cesium yield is improved to 80%~95% and the purity of cesium carbonate product is up to 99.9% by selective separation of alcohol substances in the embodiment; the solvent and filtrate can be recycled to reduce production cost, avoid multi-stage extraction steps, shorten production cycle and reduce energy consumption by more than 30%.
[0064] In the first embodiment, the method for preparing high-purity cesium carbonate from frozen mixed salt comprises the following steps:
[0065] Take 1kg of anhydrous mixed salt and 50g of anhydrous ethanol for mixing and stirring, filter the mixture after stirring, and detect the cesium content in the obtained filter residue, which is reduced from 0.112% at the beginning to 0.021%, and the cesium yield is about 80%; mix and stir the obtained filtrate and deionized water according to a mass ratio of 10:1, return the gaseous ethanol obtained after rectification to the previous step, evaporate and concentrate the cesium hydroxide solution for crystallization, stop concentrating when 60% solid appears, filter, dry the obtained wet cesium carbonate solid at 260℃, and obtain high-purity cesium carbonate after drying, and the purity of the obtained cesium carbonate is 99.98% after detection.
[0066] In the second embodiment, the method for preparing high-purity cesium carbonate from frozen mixed salt comprises the following steps:
[0067] Take 1kg of anhydrous mixed salt and 80g of anhydrous ethanol for mixing and stirring, filter the mixture after stirring, and detect the cesium content in the obtained filter residue, which is reduced from 0.112% at the beginning to 50ppm, and the cesium yield is about 95%; mix and stir the obtained filtrate and deionized water according to a mass ratio of 5:1, return the gaseous ethanol obtained after rectification to the previous step, evaporate and concentrate the cesium hydroxide solution for crystallization, stop concentrating when 60% solid appears, filter, dry the obtained wet cesium carbonate solid at 260℃, and obtain high-purity cesium carbonate after drying, and the purity of the obtained cesium carbonate is 99.97% after detection.
[0068] The applicant declares that the detailed method of the present application is illustrated by the above embodiments, but the present application is not limited to the above detailed method, that is, it does not mean that the present application must rely on the above detailed method to be implemented. It should be understood by those skilled in the art that any improvement of the present application, equivalent replacement of the method of the present application, addition of auxiliary steps, selection of specific modes, etc. fall within the protection scope and disclosure scope of the present application.
Claims
1. A method for preparing high-purity cesium carbonate from frozen mixed salt, characterized in that: include: Drying the frozen mixed salt; mixing the dried frozen mixed salt and the alcohol substance in a predetermined ratio and stirring to obtain a mixture; performing solid-liquid separation on the mixture to obtain a cesium-containing solution and a solid residue containing potassium and sodium salts; adding water to the cesium-containing solution for hydrolysis to form a solvent-water mixed phase; Separating and recovering the solvent from the solvent-water mixed phase by distillation or fractional distillation to obtain a cesium hydroxide solution; performing carbonization treatment on the cesium hydroxide solution to generate a cesium carbonate solution; Concentrating the cesium carbonate solution to a set solid-liquid ratio and then performing solid-liquid separation to obtain wet cesium carbonate and a filtrate; The wet cesium carbonate is dried to obtain a cesium carbonate product.
2. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein The alcohol compound is one or more of methanol, ethanol or propanol.
3. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein In the step of mixing and stirring the dried frozen mixed salt and the alcohol substance in a preset ratio to obtain a mixture: The mass ratio of the anhydrous mixed salt to the alcohol substance is 5-1.
4. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein In the step of adding water to the cesium-containing solution for hydrolysis to form a solvent-water mixed phase: The mass ratio of the cesium-containing solution to water is 10 to 0.
5.
5. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein The cesium hydroxide solution is subjected to carbonization treatment to generate a cesium carbonate solution: Carbon dioxide is added to the cesium hydroxide solution to achieve carbonization treatment.
6. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein In the step of concentrating the cesium carbonate solution to a set solid-liquid ratio and then performing solid-liquid separation to obtain wet cesium carbonate and a filtrate: The concentrated solid-liquid ratio is 50%-70%.
7. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein In the step of drying the wet cesium carbonate to obtain a cesium carbonate product, the drying temperature is 180° C. to 320° C.
8. The method for preparing high-purity cesium carbonate from frozen mixed salt according to claim 1, wherein The step of carbonizing the cesium hydroxide solution to generate the cesium carbonate solution further comprises: The filtrate is mixed with the cesium hydroxide solution and then carbonized to generate a cesium carbonate solution.