Method for extracting rubidium and cesium carbonate from frozen mother liquor

Abstract

The invention provides a method for extracting rubidium and cesium carbonate from frozen mother liquor, and relates to the technical field of nonferrous metallurgy. According to the method for extracting rubidium and cesium carbonate from the frozen mother liquor, rubidium and cesium are extracted from the frozen mother liquor generated in the process of producing lithium carbonate through a lepidolite roasting method, the method is simple and low in cost, the high-purity rubidium and cesium carbonate can be obtained, and full utilization of resources is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal metallurgy, and in particular to a method for extracting rubidium-cesium carbonate from a frozen mother liquor. Background Art

[0002] The rapid development of the new energy industry has brought about a rapid increase in demand for lithium resources. Lepidolite is a good lithium ore. Yichun has rich reserves of lepidolite, which ranks first in China. The rich lithium resources have also driven the vigorous development of the lithium smelting industry in Yichun.

[0003] Lepidolite ore contains a variety of valuable elements such as lithium, rubidium, cesium, tantalum, etc. The existing lepidolite smelting is mainly based on the roasting process. Lepidolite is mixed with sulfate and roasted. After roasting, it is leached in water to remove impurities and finally prepare lithium carbonate. The mother liquor of lithium precipitation is evaporated and concentrated, and potassium and sodium salts are precipitated by freezing and crystallization. The liquid is the frozen mother liquor. The frozen mother liquor also contains a large amount of rubidium and cesium that have not been extracted, resulting in a huge waste of resources. Rubidium and cesium are rare metals with excellent photoelectric properties and chemical activity. They have unique uses in various technical fields and cannot be replaced by other metal elements. In addition, rubidium and cesium are expensive. If they can be separated from the mother liquor of lithium precipitation, they will have excellent economic prospects. Invention patent CN102828052A provides a method for separating potassium, rubidium and cesium alum after extracting lithium from lepidolite raw materials, and recovers and extracts potassium, rubidium and cesium alum salts respectively. Although the valuable metal rubidium and cesium are recovered, no single rubidium and cesium salt is obtained, and the utilization rate of rubidium and cesium resources is low. Therefore, it is urgent to develop a method for extracting rubidium and cesium carbonate from frozen mother liquor to prepare high-purity rubidium and cesium salts, which is of great significance for the resource utilization of lepidolite ore. Summary of the invention

[0004] Based on the technical problems existing in the background technology, the present invention proposes a method for extracting rubidium cesium carbonate from frozen mother liquor.

[0005] The present invention provides a method for extracting rubidium cesium carbonate from a frozen mother liquor, comprising the following steps:

[0006] S1, extraction: adding sodium hydroxide to the frozen mother liquor, mixing evenly, and then adding an extractant for extraction, and the obtained organic layer is the primary extract;

[0007] S2, stripping: adding sulfuric acid solution to the primary extract for stripping, and the obtained water layer is the primary stripping solution;

[0008] S3, extraction: adding sodium hydroxide to the primary stripping solution to adjust the pH, adding an extractant for extraction, and obtaining an organic layer as the secondary extract;

[0009] S4, washing: washing the secondary extract with a detergent to obtain a cesium-rich organic phase and a rubidium-rich aqueous phase;

[0010] S5, the cesium-rich organic phase is stripped and concentrated by evaporation to obtain cesium oxalate;

[0011] S6, extracting, washing, stripping and evaporating the rubidium-rich aqueous phase to obtain rubidium oxalate;

[0012] S7. Roast rubidium oxalate and cesium oxalate respectively to obtain rubidium carbonate and cesium carbonate.

[0013] The invention effectively reduces organic consumption by first enriching and then extracting. The method has a simple process, is easy to operate, has no requirement on the concentration of rubidium and cesium in the extract, has a wide range of applications, and has high purity and yield of rubidium and cesium. The method can fully utilize rubidium and cesium resources and has good economic value.

[0014] Preferably, in S1, the frozen mother liquor is the liquid obtained by evaporation concentration and freezing crystallization of the lithium precipitation mother liquor in the process of producing lithium carbonate by sulfate roasting of lepidolite.

[0015] Preferably, in said S1, the concentrations of rubidium and cesium in the frozen mother liquor are 5-10 g / L and 1-5 g / L respectively.

[0016] Preferably, in said S1, the mass ratio of the frozen mother liquor to sodium hydroxide is 100:(1-4).

[0017] The mass ratio of frozen mother liquor to sodium hydroxide within a certain range is helpful to improve the extraction rate of rubidium and cesium and the yield of valuable ions.

[0018] Preferably, in S1, the extractant includes a diluent and a phenol-alcohol reagent; the diluent is sulfonated kerosene, and the phenol-alcohol reagent is t-BAMBP; and the concentration of the phenol-alcohol reagent in the extractant is 1-3 mol / L.

[0019] Preferably, in S1, the ratio of the extractant to the frozen mother liquor is (0.5-2):1.

[0020] Preferably, in S1, the water layer obtained after extraction is collected and reused to mix with lithium precipitation mother liquor to precipitate potassium and sodium salts.

[0021] Preferably, in S2, the concentration of the sulfuric acid solution is 1-3 mol / L, and the volume ratio of the sulfuric acid solution to the primary extract is 1:(5-20).

[0022] The concentration of sulfuric acid solution within a certain range is helpful to strip ions in the organic phase more completely while reducing costs.

[0023] Preferably, in S2, the organic layer obtained after the back extraction is collected and used as an extractant to extract rubidium and cesium.

[0024] Preferably, in S3, the water layer obtained after extraction is collected and reused to mix with the frozen mother liquor.

[0025] Preferably, in S3, the pH is adjusted to 11-14.

[0026] Controlling the extraction pH within a certain range helps to increase the yield of rubidium and cesium, while reducing the extraction emulsification phenomenon.

[0027] Preferably, in S3, the extractant includes a diluent and a phenol-alcohol reagent; the diluent is sulfonated kerosene, and the phenol-alcohol reagent is t-BAMBP; and the concentration of the phenol-alcohol reagent in the extractant is 0.5-1.5 mol / L.

[0028] Preferably, in S3, the ratio of the extractant to the primary stripping solution is (0.5-2):1.

[0029] Preferably, in S4, the detergent is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.01-0.2 mol / L.

[0030] Washing with sodium hydroxide solution can reduce the loss during the separation of rubidium and cesium.

[0031] Preferably, in S4, the ratio of the secondary extract to the detergent is (0.5-2):1.

[0032] Preferably, in said S4, the number of washing times is 1-8 times.

[0033] Preferably, in S5, the stripping comprises stripping the cesium-rich organic phase with an oxalic acid solution.

[0034] Rubidium and cesium oxalate are obtained by stripping with oxalic acid solution. The solubility of rubidium and cesium oxalate is low, which reduces the energy consumption of evaporation and crystallization.

[0035] More preferably, the ratio of the oxalic acid solution to the cesium-rich organic phase is (5-25):1.

[0036] More preferably, the concentration of the oxalic acid solution is 0.5-1.5 mol / L.

[0037] Preferably, in S5, the temperature of evaporation and concentration is 80-150°C.

[0038] Preferably, in S6, the extraction comprises adding sodium hydroxide to the rubidium-rich aqueous phase, mixing evenly, and then adding an extractant for extraction, and the obtained organic layer is a rubidium-rich organic phase.

[0039] More preferably, sodium hydroxide is added to adjust the pH to 12-14.

[0040] More preferably, the extractant comprises a diluent and a phenol-alcohol reagent; the diluent is sulfonated kerosene, and the phenol-alcohol reagent is t-BAMBP; and the concentration of the phenol-alcohol reagent in the extractant is 1-3 mol / L.

[0041] More preferably, the ratio of the extractant to the rubidium-rich aqueous phase is (0.5-3):1.

[0042] Preferably, in S6, the washing liquid is pure water, the ratio of the rubidium-rich organic phase to the washing liquid is (5-10):1, and the number of washing times is 1-3 times.

[0043] Compared with the washing liquid, the rubidium-rich organic phase can help reduce the rubidium loss in the washing process and reduce the amount of washing liquid used within a certain range.

[0044] Preferably, in S6, the stripping comprises stripping the rubidium-rich organic phase with an oxalic acid solution.

[0045] More preferably, the ratio of the oxalic acid solution to the rubidium-rich organic phase is (5-10):1.

[0046] Preferably, in S6, the temperature of evaporation and concentration is 90-150°C.

[0047] Preferably, in said S7, the calcination temperature is 550-750°C.

[0048] The calcination temperature within a certain range is helpful to improve the conversion rate of rubidium-cesium oxalate into rubidium-cesium carbonate and obtain pure rubidium-cesium carbonate.

[0049] The beneficial effects of the present invention are:

[0050] The invention discloses a method for extracting rubidium and cesium carbonate from frozen mother liquor. The frozen mother liquor produced in the process of producing lithium carbonate by calcining lithium mica is used as a raw material to extract rubidium and cesium. The frozen mother liquor is firstly extracted and enriched. Compared with other methods, the utilization rate of the extractant is improved, the amount and loss of the extractant are reduced, and the water consumption in the production process is reduced. The method is simple, the cost is low, and high-purity rubidium and cesium carbonate can be obtained, so that resources are fully utilized. The purity of the cesium carbonate and rubidium carbonate products obtained by the method of the invention is greater than 99%. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The present invention is a process flow chart of the method for extracting rubidium cesium carbonate from frozen mother liquor. DETAILED DESCRIPTION

[0052] The technical solution of the present invention is described in detail through specific embodiments.

[0053] Unless otherwise specified, the materials, reagents, etc. used in the following examples and comparative examples can be obtained from commercial sources.

[0054] The composition of the frozen mother liquor is shown in Table 1. The pH of the frozen mother liquor is 9.8.

[0055] Table 1

[0056] element <![CDATA[Li2O]]> Na K R Cs Concentration (g / L) 27.21 27.45 30.75 8.83 1.96

[0057] Example 1

[0058] A method for extracting rubidium cesium carbonate from a frozen mother liquor comprises the following steps:

[0059] S1, extraction: t-BAMBP is added to sulfonated kerosene to dilute to a concentration of 2 mol / L to obtain an extractant, sodium hydroxide is added to the frozen mother liquor to make the sodium hydroxide concentration in the frozen mother liquor 20 g / L, and the extractant is added for extraction, the volume ratio of the extractant to the frozen mother liquor is 0.5:1, and the aqueous layer and the organic layer are separated after standing, and the organic layer is the primary extract; the aqueous layer is collected and reused with the lithium precipitation mother liquor to prepare potassium sodium salt;

[0060] S2, stripping: add 2 mol / L sulfuric acid solution to the primary extract for stripping, the volume ratio of sulfuric acid solution to the primary extract is 1:5; stand and separate the water layer and the organic layer, the organic layer is reused as an extractant to extract rubidium and cesium, and the obtained water layer is the primary stripping solution;

[0061] S3, extraction: sodium hydroxide is added to the primary stripping solution to adjust the pH to 14, and an extractant is added for extraction, wherein the volume ratio of the extractant to the primary stripping solution is 0.5:1; after standing and separating, the aqueous phase is collected and mixed with the frozen mother liquor for reuse, and the obtained organic layer is the secondary extract; wherein the extractant is t-BAMBP, and the extractant is diluted with sulfonated kerosene to a concentration of 1 mol / L;

[0062] S4, washing: washing the secondary extract with 0.1 mol / L sodium hydroxide solution for 4 times, with the volume ratio of the secondary extract to the washing solution being 2:1, to obtain a cesium-rich organic phase and a rubidium-rich aqueous phase;

[0063] S5, mixing the cesium-rich organic phase with a 0.8 mol / L oxalic acid solution for stripping, the stripping conditions being: the stripping phase ratio (O / A) being 10:1, to obtain a cesium-rich stripping solution, and evaporating and concentrating the cesium-rich stripping solution at 130° C. to obtain cesium oxalate;

[0064] S6. Add sodium hydroxide to the rubidium-rich aqueous phase to adjust the pH to 14, add an extractant for extraction, and the volume ratio of the extractant to the rubidium-rich aqueous phase is 1:1; after standing and separating, the organic phase is the rubidium-extracted organic phase, and the aqueous phase is collected and mixed with a stripping liquid for reuse; the rubidium-extracted organic phase is washed twice with pure water, and the volume ratio of the rubidium-extracted organic phase to pure water is 10:1. After the washing, the organic phase is the rubidium-rich organic phase, and the aqueous phase is the washing liquid; 0.5 mol / L oxalic acid solution is mixed with the rubidium-rich organic phase for stripping, and the stripping conditions are: the stripping phase ratio (O / A) is 5:1, and a rubidium-rich stripping liquid is obtained, and the cesium-rich stripping liquid is evaporated and concentrated at 130°C to obtain rubidium oxalate;

[0065] S7. Roast rubidium oxalate and cesium oxalate in a muffle furnace at 700° C. for 5 hours to obtain rubidium carbonate and cesium carbonate. The purity of cesium carbonate is 99.4%, the purity of rubidium carbonate is 99%, the comprehensive yield of cesium is 90%, and the comprehensive yield of rubidium is 82%.

[0066] The components of rubidium oxalate and cesium oxalate in S5 and S6 were tested, and the test results are shown in Table 2.

[0067] Table 2

[0068] element Li Na K R Cs Cesium oxalate solution (g / L) 0.001 0.07 0.002 0.012 14.5 Rubidium oxalate solution (g / L) 0.005 0.01 0.005 5.55 0.03

[0069] Example 2

[0070] A method for extracting rubidium cesium carbonate from a frozen mother liquor comprises the following steps:

[0071] S1, extraction: t-BAMBP is added to sulfonated kerosene to dilute to a concentration of 1 mol / L to obtain an extractant, sodium hydroxide is added to the frozen mother liquor to make the sodium hydroxide concentration in the frozen mother liquor 10 g / L, and the extractant is added for extraction, the volume ratio of the extractant to the frozen mother liquor is 1:1, and the aqueous layer and the organic layer are separated after standing, and the organic layer is the primary extract; the aqueous layer is collected and reused with the lithium precipitation mother liquor to prepare potassium sodium salt;

[0072] S2, stripping: add 1 mol / L sulfuric acid solution to the primary extract for stripping, the volume ratio of sulfuric acid solution to the primary extract is 1:10; stand and separate the water layer and the organic layer, the organic layer is reused as an extractant to extract rubidium and cesium, and the obtained water layer is the primary stripping solution;

[0073] S3, extraction: sodium hydroxide is added to the primary stripping solution to adjust the pH to 13, and an extractant is added for extraction, wherein the volume ratio of the extractant to the primary stripping solution is 0.5:1; after standing and separating, the aqueous phase is collected and mixed with the frozen mother liquor for reuse, and the obtained organic layer is the secondary extract; wherein the extractant is t-BAMBP, and sulfonated kerosene is added to dilute the extractant to a concentration of 1 mol / L;

[0074] S4, washing: washing the secondary extract with 0.05 mol / L sodium hydroxide solution for 5 times, with the volume ratio of the secondary extract to the washing solution being 1:1, to obtain a cesium-rich organic phase and a rubidium-rich aqueous phase;

[0075] S5, mixing the cesium-rich organic phase with a 1 mol / L oxalic acid solution for stripping, the stripping conditions being: a stripping phase ratio (O / A) of 5:1, to obtain a cesium-rich stripping solution, and evaporating and concentrating the cesium-rich stripping solution at 130° C. to obtain cesium oxalate;

[0076] S6. Add sodium hydroxide to the rubidium-rich aqueous phase to adjust the pH to 14, add an extractant for extraction, and the volume ratio of the extractant to the rubidium-rich aqueous phase is 1:1; after standing and separating, the organic phase is the rubidium-extracted organic phase, and the aqueous phase is collected and mixed with a stripping liquid for reuse; wash the rubidium-extracted organic phase with pure water twice, and the volume ratio of the rubidium-extracted organic phase to pure water is 10:1. After the washing, the organic phase is the rubidium-rich organic phase, and the aqueous phase is the washing liquid; mix the rubidium-rich organic phase with a 1 mol / L oxalic acid solution for stripping, and the stripping conditions are: the stripping phase ratio (O / A) is 5:1, and a rubidium-rich stripping liquid is obtained, and the cesium-rich stripping liquid is evaporated and concentrated at 130°C to obtain rubidium oxalate;

[0077] S7. Roast rubidium oxalate and cesium oxalate in a muffle furnace at 650° C. for 5 hours to obtain rubidium carbonate and cesium carbonate. The purity of cesium carbonate is 99%, the purity of rubidium carbonate is 99%, the comprehensive yield of cesium is 81%, and the comprehensive yield of rubidium is 74%.

[0078] The components of rubidium oxalate and cesium oxalate in S5 and S6 were tested, and the test results are shown in Table 3.

[0079] Table 3

[0080] element Li Na K R Cs Cesium oxalate solution (g / L) 0.002 0.02 0.002 0.02 5.4 Rubidium oxalate solution (g / L) 0.0025 0.001 0.005 5.54 0.015

[0081] Example 3

[0082] A method for extracting rubidium cesium carbonate from a frozen mother liquor comprises the following steps:

[0083] S1, extraction: t-BAMBP is added to sulfonated kerosene to dilute to a concentration of 2 mol / L to obtain an extractant, sodium hydroxide is added to the frozen mother liquor to make the sodium hydroxide concentration in the frozen mother liquor 30 g / L, and the extractant is added for extraction, the volume ratio of the extractant to the frozen mother liquor is 0.5:1, and the aqueous layer and the organic layer are separated after standing, and the organic layer is the primary extract; the aqueous layer is collected and reused with the lithium precipitation mother liquor to prepare potassium sodium salt;

[0084] S2, stripping: add 1 mol / L sulfuric acid solution to the primary extract for stripping, the volume ratio of sulfuric acid solution to the primary extract is 1:10; stand and separate the water layer and the organic layer, the organic layer is reused as an extractant to extract rubidium and cesium, and the obtained water layer is the primary stripping solution;

[0085] S3, extraction: sodium hydroxide is added to the primary stripping solution to adjust the pH to 13, and an extractant is added for extraction, wherein the volume ratio of the extractant to the primary stripping solution is 0.5:1; after standing and separating, the aqueous phase is collected and mixed with the frozen mother liquor for reuse, and the obtained organic layer is the secondary extract; wherein the extractant is t-BAMBP, and sulfonated kerosene is added to dilute the extractant to a concentration of 1 mol / L;

[0086] S4, washing: washing the secondary extract with 0.2 mol / L sodium hydroxide solution for 8 times, with the volume ratio of the secondary extract to the washing solution being 1:1, to obtain a cesium-rich organic phase and a rubidium-rich aqueous phase;

[0087] S5, mixing the cesium-rich organic phase with a 1.2 mol / L oxalic acid solution for stripping, the stripping conditions being: a stripping phase ratio (O / A) of 5:1, to obtain a cesium-rich stripping solution, and evaporating and concentrating the cesium-rich stripping solution at 130° C. to obtain cesium oxalate;

[0088] S6. Add sodium hydroxide to the rubidium-rich aqueous phase to adjust the pH to 13, add an extractant to extract, and the volume ratio of the extractant to the rubidium-rich aqueous phase is 0.5:1; after standing and separating, the organic phase is the rubidium-extracted organic phase, and the aqueous phase is collected and mixed with a stripping liquid for reuse; wash the rubidium-extracted organic phase with pure water three times, and the volume ratio of the rubidium-extracted organic phase to pure water is 5:1. After the washing, the organic phase is the rubidium-rich organic phase, and the aqueous phase is the washing liquid; mix the rubidium-rich organic phase with 0.8 mol / L oxalic acid solution for stripping, and the stripping conditions are: the stripping phase ratio (O / A) is 5:1 to obtain a rubidium-rich stripping liquid, and evaporate and concentrate the cesium-rich stripping liquid at 130°C to obtain rubidium oxalate;

[0089] S7. Roast rubidium oxalate and cesium oxalate in a muffle furnace at 650° C. for 5 hours to obtain rubidium carbonate and cesium carbonate. The purity of cesium carbonate is 99.2%, the purity of rubidium carbonate is 99%, the comprehensive yield of cesium is 64%, and the comprehensive yield of rubidium is 42%.

[0090] The components of rubidium oxalate and cesium oxalate in S5 and S6 were tested, and the test results are shown in Table 4.

[0091] Table 4

[0092] element Li Na K R Cs Cesium oxalate solution (g / L) 0.001 0.02 0.001 0.005 4.3 Rubidium oxalate solution (g / L) 0.001 0.005 0.002 3.1 0.008

[0093] Comparative Example 1

[0094] The difference between this comparative example and Example 1 is that the stripping agent in S5 and S6 in Example 1 is replaced by sulfuric acid instead of oxalic acid, and other conditions remain unchanged. Rubidium sulfate and cesium sulfate solutions are obtained by this method. After evaporation and concentration, the purity of the rubidium sulfate and cesium sulfate crystals obtained after roasting is 93.2% and 90.6% respectively.

[0095] Comparative Example 2

[0096] The difference between this comparative example and Example 1 is that the stripping agent in S5 and S6 in Example 1 is replaced by a carbonate solution formed by passing high-purity carbon dioxide gas into pure water instead of oxalic acid, and other conditions remain unchanged. After the above steps, the recovery rates of rubidium and cesium are 70% and 80% respectively.

[0097] According to the above-mentioned embodiments 1-3 and comparative examples 1-2, due to the high solubility of rubidium cesium sulfate, rubidium cesium carbonate, etc., evaporation and crystallization are difficult, and anions remain after evaporation, the recovery rate is reduced, and the sample purity is unqualified. The present invention makes full use of the low solubility of rubidium cesium oxalate, reduces the difficulty of crystallization of rubidium cesium salt, and improves the recovery rate of rubidium cesium. The method of extracting rubidium cesium carbonate from frozen mother liquor of the present invention is improved compared with the recovery rate of rubidium and cesium in comparative examples 1-2, and the product purity will be greatly improved, and the purity of the obtained rubidium cesium carbonate is high, so that the full utilization of resources is achieved.

[0098] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for extracting rubidium cesium carbonate from a frozen mother liquor, characterized in that: The following steps are involved: S1, extraction: adding sodium hydroxide to the frozen mother liquor, mixing evenly, and then adding an extractant for extraction, and the obtained organic layer is the primary extract; S2, stripping: adding sulfuric acid solution to the primary extract for stripping, and the obtained water layer is the primary stripping solution; S3, extraction: adding sodium hydroxide to the primary stripping solution to adjust the pH, adding an extractant for extraction, and obtaining an organic layer as the secondary extract; S4, washing: washing the secondary extract with a detergent to obtain a cesium-rich organic phase and a rubidium-rich aqueous phase; S5, the cesium-rich organic phase is stripped and concentrated by evaporation to obtain cesium oxalate; S6, extracting, washing, stripping and evaporating the rubidium-rich aqueous phase to obtain rubidium oxalate; S7. Roast rubidium oxalate and cesium oxalate respectively to obtain rubidium carbonate and cesium carbonate.

2. The method according to claim 1, characterized in that In the S1, the mass ratio of the frozen mother liquor to the sodium hydroxide is 100:(1-4).

3. The method according to claim 1, characterized in that In the S2, the concentration of the sulfuric acid solution is 1-3 mol / L, and the volume ratio of the sulfuric acid solution to the primary extract is 1:(5-20).

4. The method according to claim 1, characterized in that: In the S3, the pH is adjusted to 11-14.

5. The method according to claim 1, characterized in that In the S4, the detergent is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.01-0.2 mol / L.

6. The method according to claim 1, characterized in that In the S5, the stripping includes stripping the cesium-rich organic phase with an oxalic acid solution.

7. The method according to claim 1, characterized in that In the S6, the washing liquid is pure water, the ratio of the rubidium-rich organic phase to the washing liquid is (5-10):1, and the washing times are 1-3 times.

8. The method according to claim 1, characterized in that: In the above-mentioned S7, the calcination temperature is 550-750°C.

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