Method for selectively precipitating and separating rubidium and cesium from secondary zinc oxide powder alkali wash

Abstract

The invention discloses a method for selectively precipitating and separating rubidium and cesium from a zinc hypoxide powder alkali wash solution, and belongs to the technical field of non-ferrous metallurgy, the method specifically comprises the following steps: adjusting the pH value of the zinc hypoxide powder alkali wash solution to 1-5, then adding a precipitant phosphotungstic acid into the zinc hypoxide powder alkali wash solution at 20-25 DEG C, mixing for 40-120 minutes to obtain a mixed solution, and carrying out solid-liquid separation to obtain the rubidium and cesium powder. A clarified solution I and a cesium-enriched product are obtained; adding phosphotungstic acid into the clarified liquor I at 40-80 DEG C, stirring and mixing for 90-240 minutes to obtain mixed liquor, and performing solid-liquid separation to obtain clarified liquor II and rubidium enrichment; according to the method disclosed by the invention, rubidium and cesium are separated and recovered step by step from the secondary zinc oxide powder alkali wash solution in a two-stage precipitation manner by taking phosphotungstic acid as a precipitator, and a high-content enriched product of rubidium and cesium is obtained, so that selective precipitation separation of rubidium and cesium in the secondary zinc oxide powder alkali wash solution can be realized; the method has the advantages of short process flow, simplicity in operation, low reagent consumption, high rubidium and cesium precipitation rate and the like.

Description

TECHNICAL FIELD

[0001] The application relates to a method for selectively precipitating and separating rubidium and cesium from a zinc suboxide powder alkali washing solution and belongs to the technical field of nonferrous metallurgy. BACKGROUND

[0002] Rubidium and cesium are extremely important rare and valuable metal resources. With the rapid development of new energy, new materials and other high-tech industries, rubidium and cesium are not only widely used in strategic emerging industries such as aerospace, national defense and military industry and information technology, but also have a place in high-tech fields such as magnetic fluid power generation, cesium (rubidium) atomic clock, energy converter and ion thruster, perovskite battery, and are known as the “peerless double” in rare metals.

[0003] Zinc-containing dust generated in the process of steel or nonferrous smelting contains fluorine, chlorine, zinc, potassium and sodium and cannot be directly utilized, and needs to be washed with water / alkali to remove fluorine and chlorine. When alkali washing is used to remove fluorine and chlorine in the process of zinc hydrometallurgy, alkali metal ions are dissolved into the alkali washing solution at the same time, which is an important rubidium and cesium resource and has high recycling value. Sodium, potassium, rubidium and cesium and their compounds have many similar physicochemical properties (ion valence, radius and hydration radius, solvent coordination ability, compound solubility, etc.), and it is difficult to achieve efficient and complete separation. Therefore, reasonable development and utilization of rubidium and cesium resources in the alkali washing solution of zinc suboxide powder has become a research hotspot in China at present, and has certain guiding significance for efficient separation and resource utilization of potassium, rubidium and cesium in high-potassium and high-sodium wastewater.

[0004] At present, the methods for extracting rubidium and cesium from a solution mainly include solvent extraction, precipitation, ion exchange and fractional crystallization. The extraction method has high selectivity, large treatment capacity and is easy to operate, but needs repeated extraction and stripping, is prone to emulsification, and has problems such as high price of extractant, toxicity of diluent and the like. Common extractants include phenolic extractants t-BAMBP and crown ether extractants 15 crown 5 and 18 crown 6; the precipitants used in the precipitation method mainly include heteropoly acids, complex acid salts, polyhalides, metal ferricyanides and alum salts. The precipitation reagent has the advantages of various types, high selectivity, high recovery rate and easy operation, but has the disadvantages of complex precipitation process, high price of reagent and inability of the precipitant to be regenerated; the ion exchange method has the advantages of simple process flow and high recovery rate, but has the disadvantages of poor heat resistance, radiation resistance and selectivity of organic ion exchangers; Chinese patent 201910583379.6 proposes a method for separating rubidium and cesium in aqueous solution by precipitating and floating, which uses phosphotungstate as a precipitant to react with rubidium and cesium to form a precipitate, and then uses the foam surface tension to float out the fine particles by flotation method, so as to realize the separation of rubidium and cesium. Chinese patent 202211131376.7 proposes a method for separating rubidium and cesium from high-salt mother liquor, which uses soluble transition metal salt and soluble ferrocyanide to form rubidium and cesium-containing ferrocyanide to extract rubidium and cesium, but there are problems such as small particle size, poor strength and difficulty in filtration.

[0005] In summary, there are still some problems in separating rubidium and cesium, such as the influence of organic residues in the aqueous phase in the extraction process, the high price of organic extractants, etc.; the high cost of reagents in the precipitation process, the inability to regenerate the precipitant, etc.; the loss of rubidium and cesium in the crystallization process, and the complex process flow, etc. SUMMARY

[0006] In view of the problems existing in the prior art, the present application provides a method for selectively precipitating and separating rubidium and cesium from a zinc suboxide powder alkali washing solution, which uses phosphotungstic acid as a precipitant and adopts a two-stage precipitation method to separate and recover rubidium and cesium step by step, and obtains rubidium and cesium-rich products with high content.

[0007] The method for selectively precipitating and separating rubidium and cesium from a zinc suboxide powder alkali washing solution according to the present application is as follows: 1. Adjust the pH of the zinc suboxide powder alkali washing solution to 1-5, then add the precipitant phosphotungstic acid to the zinc suboxide powder alkali washing solution at 20-25°C, stir and mix for 40-120 min to obtain a mixed solution, and then separate the solid and liquid to obtain a clear solution I and a cesium-rich product; The zinc suboxide powder alkali washing solution contains potassium, sodium, lithium, rubidium, cesium, chlorine and other ions, wherein the concentration of rubidium ions is 4-6 g / L, and the concentration of cesium ions is 3-7 g / L; The addition amount of the precipitant phosphotungstic acid is 0.8-1.4 times the theoretical amount of reaction with rubidium and cesium; the stirring speed is 400-600 rpm; and 8-12 mol / L hydrochloric acid aqueous solution is used to adjust the pH; The cesium-rich product is obtained preferentially because the ionic radius of cesium is larger than that of rubidium and the metal activity of cesium is stronger; After the first precipitation, the concentration of rubidium ions in the clear solution I is 3-5 g / L, the concentration of cesium ions is 0.1-0.5 g / L, the content of rubidium in the cesium-rich product is 0.5%-1.5%, and the content of cesium is 3%-4.5%; 2. adding phosphotungstic acid in the clear solution I at 40~80℃, mixing and stirring for 90~240min to obtain a mixed solution, and then solid-liquid separation to obtain a clear solution II and a rubidium enrichment; after secondary precipitation, the concentration of rubidium ion in the clear solution II is 0.01~1g / L, and the concentration of cesium ion is 0.0001~0.01g / L; the content of rubidium in the rubidium enrichment is 1.5%~3%, and the content of cesium is 0.1%~0.5%; The amount of phosphotungstic acid added is 1.3~1.9 times of the theoretical reaction amount of rubidium and cesium reaction; the stirring speed is 400~600rpm.

[0008] The above theoretical reaction amount of rubidium and cesium reaction is calculated according to the following chemical reaction formula: ; The beneficial effects of the present application are: (1) The method can efficiently realize the selective precipitation separation of rubidium and cesium in the alkali washing solution of secondary zinc oxide powder, the selectivity of phosphotungstic acid to cesium is high in an acidic medium, the high charge density and cavity size of the anion of the precipitant are more easily combined with the cesium ion with large radius and low charge density, and the enrichment of cesium is preferentially obtained, so that the step-by-step enrichment of rubidium and cesium is realized; the two-stage precipitation method of the present application with phosphotungstic acid as the precipitant preferentially precipitates cesium and then precipitates rubidium, realizes the step-by-step separation and recovery of rubidium and cesium, is beneficial to the comprehensive recovery of rubidium and cesium secondary resources in secondary zinc oxide powder, and improves the utilization rate of rubidium and cesium resources and the resource recovery of secondary zinc oxide powder; (2) The method can obtain high rubidium and cesium content enrichment. It has the advantages of short process flow, simple operation, high rubidium and cesium precipitation rate, etc. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 is the SEM spectrum of the cesium and rubidium enrichment prepared by the embodiment 3 of the present application, wherein figure a is the SEM spectrum of the cesium enrichment, and figure b is the SEM spectrum of the rubidium enrichment;

[0010] Figure 2 is the process flow diagram of the selective precipitation separation of rubidium and cesium. DETAILED DESCRIPTION

[0011] The present application will be further described by specific examples, but should not be understood as being limited to the following examples. Within the scope of knowledge possessed by those skilled in the art, the technical solutions of the following examples can still be replaced or changed without departing from the above-mentioned idea of the present application, which still belongs to the protection scope of the present application. These modifications or replacements do not make the essence of the corresponding technical solution deviate from the scope of the technical solutions of the embodiments of the present application. Example 1

[0012] 1. Take 500 mL of zinc suboxide powder lye and place it in a beaker, wherein the zinc suboxide powder lye contains rubidium ions 4.99 g / L and cesium ions 5.02 g / L; add 9 mol / L hydrochloric acid solution to the zinc suboxide powder lye to adjust the pH of the lye to 3.99; 2. Place the beaker of step 1 in an oil bath at 20℃, add phosphotungstic acid 55.37 g, stir at 500 r / min for 60 min, then filter to obtain 470 mL of post-precipitation liquid; dry the precipitate in a 70℃ oven for 4 h, then weigh 49.2 g; the contents of rubidium and cesium in the first-stage precipitate are 0.97% and 3.04% respectively, and the SEM spectrum is shown in Figure 1 a; the concentrations of rubidium and cesium in the post-precipitation liquid are 3.65 g / L and 0.37 g / L respectively, as detected by flame atomic absorption method, and the removal rates of rubidium and cesium are 26.85% and 92.65% respectively; 3. Place 470 mL of post-precipitation liquid in a 40℃ oil bath, add phosphotungstic acid 45.12 g, stir for 120 min, then filter to obtain 450 mL of filtrate, dry the precipitate in a 70℃ drying oven for 4 h, then weigh 42.39 g; the contents of rubidium and cesium in the second-stage precipitate are 2.08% and 0.48% respectively, and the SEM spectrum is shown in Figure 1 b; return the filtrate to the zinc suboxide powder lye for recycling extraction, and the concentrations of rubidium and cesium in the filtrate are 0.96 g / L and 0.011 g / L respectively, as detected by flame atomic absorption method, and the removal rates of rubidium and cesium are 73.69% and 97.03% respectively Figure 2 ). Example 2

[0013] 1. Take 500 mL of zinc suboxide powder lye and place it in a beaker, wherein the zinc suboxide powder lye contains rubidium ions 5.89 g / L and cesium ions 6.88 g / L; add 10 mol / L hydrochloric acid solution to the zinc suboxide powder lye to adjust the pH of the lye to 2.19; 2. Place the beaker of step 1 in an oil bath at 20℃, add phosphotungstic acid 55.37 g, stir at 500 r / min for 90 min, then filter to obtain 470 mL of post-precipitation liquid; dry the precipitate in an 80℃ oven for 5 h, then weigh 49.4 g; the contents of rubidium and cesium in the first-stage precipitate are 1.33% and 3.56% respectively; the concentrations of rubidium and cesium in the post-precipitation liquid are 4.53 g / L and 0.46 g / L respectively, as detected by flame atomic absorption method, and the removal rates of rubidium and cesium are 23.09% and 93.35% respectively.

[0014] 3, 470 mL of the precipitated solution was placed in an 80 °C oil bath, 49.37 g of phosphotungstic acid was added, and the reaction was stirred for 150 min. After filtration, 450 mL of filtrate was obtained. The precipitate was placed in a 70 °C drying oven and dried for 4 h, and the weight was recorded as 45.14 g. The contents of rubidium and cesium in the second-stage precipitate were 1.68% and 0.23%, respectively. The filtrate was returned to the zinc suboxide powder alkali washing solution. The concentrations of rubidium and cesium in the filtrate were 0.65 g / L and 0.009 g / L, respectively, as detected by flame atomic absorption spectrometry. The removal rates of rubidium and cesium were 85.65% and 98.04%, respectively. Example 3

[0015] 1, 500 mL of zinc suboxide powder alkali washing solution was taken in a beaker, wherein the zinc suboxide powder alkali washing solution contained 5.89 g / L of rubidium ions and 6.88 g / L of cesium ions. 10 mol / L hydrochloric acid aqueous solution was added to the zinc suboxide powder alkali washing solution to adjust the pH of the alkali washing solution to 2.19. 2, the beaker of step 1 was placed in an oil bath at room temperature 20 °C, 55.37 g of phosphotungstic acid was added, and the stirring speed was 500 r / min. After stirring for 120 min, the precipitate was filtered to obtain 470 mL of the precipitated solution. The precipitate was placed in an 80 °C oven and dried for 6 h, and the weight was recorded as 46.6 g. The contents of rubidium and cesium in the first-stage precipitate were 1.31% and 3.22%, respectively. The concentrations of rubidium and cesium in the precipitated solution were 4.13 g / L and 0.34 g / L, respectively, as detected by flame atomic absorption spectrometry. The removal rates of rubidium and cesium were 29.88% and 95.06%, respectively. 3, 470 mL of the precipitated solution was placed in an 80 °C oil bath, 49.37 g of phosphotungstic acid was added, and the reaction was stirred for 150 min. After filtration, 450 mL of filtrate was obtained. The precipitate was placed in a 70 °C drying oven and dried for 4 h, and the weight was recorded as 45.14 g. The contents of rubidium and cesium in the second-stage precipitate were 1.68% and 0.23%, respectively. The filtrate was returned to the zinc suboxide powder alkali washing solution. The concentrations of rubidium and cesium in the filtrate were 0.65 g / L and 0.009 g / L, respectively, as detected by flame atomic absorption spectrometry. The removal rates of rubidium and cesium were 85.65% and 98.04%, respectively.

Claims

1. A method for selectively precipitating and separating rubidium and cesium from a zinc oxide powder alkaline washing solution, characterized in that: Here are the steps: (1) The pH of the secondary zinc oxide powder alkaline washing solution is adjusted to 1-5, and then a precipitant, phosphotungstic acid, is added to the secondary zinc oxide powder alkaline washing solution at 20-25°C, and the mixture is stirred for 40-120 minutes to obtain a mixed solution, and the solid-liquid separation is performed to obtain a clarified solution I and a cesium enriched product; (2) Phosphotungstic acid is added to the clarified liquid I at 40-80°C and stirred for 90-240 minutes to obtain a mixed liquid, and the solid-liquid separation is performed to obtain clarified liquid II and rubidium-enriched product.

2. The method for selectively precipitating and separating rubidium and cesium from a secondary zinc oxide powder alkali wash according to claim 1, wherein: In step (1), the amount of phosphotungstic acid added as a precipitant is 0.8 to 1.4 times the theoretical amount for reaction with rubidium and cesium.

3. The method for selectively precipitating and separating rubidium and cesium from a secondary zinc oxide powder alkali wash according to claim 1, wherein: The amount of phosphotungstic acid added in step (2) is 1.3 to 1.9 times the theoretical reaction amount for reacting with rubidium and cesium.

4. The method for selectively precipitating and separating rubidium and cesium from a secondary zinc oxide powder alkali wash according to claim 1, wherein: The pH was adjusted using 8-12 mol / L hydrochloric acid aqueous solution.

5. The method for selectively precipitating and separating rubidium and cesium from a secondary zinc oxide powder alkaline washing solution according to claim 1, wherein: The stirring speed is 400~600rpm.

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