Method for recovering lithium, rubidium and cesium from lithium ore

Abstract

The invention discloses a method for recovering lithium, rubidium and cesium from lithium ore, and belongs to the technical field of lithium ore recovery. The method for recovering the lithium, the rubidium and the cesium from the lithium ore comprises the following steps: carrying out primary roasting on the lithium ore to obtain a primary roasting product, then mixing the primary roasting product with sulfuric acid, carrying out secondary roasting to obtain a secondary roasting product, and carrying out water leaching to obtain a solution containing the lithium, the rubidium and the cesium; adding a lithium extraction agent into the solution containing lithium, rubidium and cesium, carrying out lithium extraction to obtain a lithium extraction solution and a raffinate 1, and carrying out lithium reverse extraction and pyrolysis to obtain lithium carbonate; adding a cesium extraction agent into the raffinate 1, carrying out cesium extraction to obtain cesium extraction liquid and raffinate 2, and carrying out cesium reverse extraction and pyrolysis to obtain cesium carbonate; adding a cesium extraction agent into the raffinate 2, and carrying out cesium secondary extraction to obtain cesium secondary extraction liquid and raffinate 3; and adding a rubidium extraction agent into the raffinate 3, and carrying out rubidium extraction, rubidium reverse extraction and pyrolysis to obtain rubidium carbonate.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ore recovery, and in particular to a method for recovering lithium, rubidium and cesium from lithium ore. Background Art

[0002] With the rapid development of the new energy battery industry, the supply of lithium battery raw materials is in short supply, and the process technology of how to recover lithium from lithium ore has gradually received attention. However, there are many other rare metals (rubidium, cesium, etc.) in lithium ore; rubidium and cesium have been increasingly widely used in high-tech and emerging technology fields such as national defense and military industry due to their excellent photoelectric properties and unique chemical properties. Lithium ore is an important resource for extracting rubidium and cesium. However, the current extraction method makes it difficult to separate these three metals efficiently and with high purity. How to reasonably extract lithium, rubidium and cesium metals from lithium ore is an important issue currently faced by R&D personnel.

[0003] At present, the industrial methods for extracting lithium from lithium ore are mainly divided into sulfate roasting, sulfuric acid aging, chlorination roasting, etc. Although these methods can recover lithium in large quantities to a certain extent, the recovery of rubidium and cesium is only 20%-30%. In addition, the existing related processes generally have problems such as high roasting temperature, high energy consumption, equipment corrosion, and inability to scale production. Therefore, in the technical field of extracting lithium, rubidium and cesium from lithium ore, there is an urgent need for a method for recovering lithium, rubidium and cesium that is efficient, energy-saving, and suitable for large-scale production. Summary of the invention

[0004] The purpose of the present invention is to provide a method for recovering lithium rubidium and cesium from lithium ore to solve the above-mentioned problems in the background technology. The present invention has a short process, good extraction efficiency, energy saving, high economic benefits, can greatly reduce pollution and costs, and is suitable for large-scale industrial production.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the technical solutions of the present invention is to provide a method for recovering lithium, rubidium and cesium from lithium ore, wherein a 10wt% tributyl phosphate (TBP) kerosene solution is used as a lithium extractant (referred to as ZK953 extractant), a 15wt% tri(2,5-xylyl)phosphine kerosene solution is used as a cesium extractant (referred to as ZK960 extractant), and a 25wt% tri(2,5-xylyl)phosphine kerosene solution is used as a rubidium extractant (referred to as ZK960 extractant), and the lithium, rubidium and cesium-containing solution obtained by water leaching the lithium ore is extracted in sequence according to the order of lithium, cesium and rubidium to obtain a lithium extract, a cesium extract and a rubidium extract.

[0007] Preferably, the kerosene is 260# sulfonated kerosene.

[0008] Preferably, the obtained lithium extract, cesium extract and rubidium extract are respectively stripped using water and stripping gas to obtain lithium bicarbonate, cesium bicarbonate and rubidium bicarbonate; the lithium bicarbonate, cesium bicarbonate and rubidium bicarbonate are respectively pyrolyzed to obtain lithium carbonate, cesium carbonate and rubidium carbonate; and the stripping gas is CO2.

[0009] Preferably, the method for recovering lithium rubidium cesium comprises the following steps:

[0010] The lithium ore is primarily roasted to obtain a primary roasted product, which is then mixed with sulfuric acid, and then secondarily roasted to obtain a secondary roasted product, which is then leached in water to obtain a lithium-rubidium-cesium solution;

[0011] adding a lithium extractant to the lithium-containing rubidium-cesium solution to perform lithium extraction to obtain a lithium extract and a raffinate 1, performing lithium stripping on the lithium extract to obtain a lithium bicarbonate solution, and performing pyrolysis to obtain lithium carbonate;

[0012] adding a cesium extractant to the raffinate 1 to perform cesium extraction to obtain a cesium extract and a raffinate 2, performing cesium stripping on the cesium extract to obtain a cesium bicarbonate solution, and performing pyrolysis to obtain cesium carbonate;

[0013] Adding a cesium extractant to the raffinate 2 to perform a cesium secondary extraction to obtain a cesium secondary extract and a raffinate 3;

[0014] A rubidium extractant is added to the raffinate 3 to perform rubidium extraction to obtain a rubidium extract and a raffinate 4. The rubidium extract is stripped to obtain a rubidium bicarbonate solution, which is thermally decomposed to obtain rubidium carbonate.

[0015] The blank organic phase obtained after stripping can be directly recycled.

[0016] Preferably, the lithium ore is spodumene; the temperature of the initial roasting is 1070-1100° C., and the time is 2 hours.

[0017] Preferably, the mass ratio of the primary calcination product to sulfuric acid is 5:2; the temperature of the secondary calcination is 280° C., and the time is 2 h.

[0018] Preferably, the pH value of the lithium extraction is 9-11.

[0019] Preferably, the pH value of the cesium extraction is 12-12.5; and the pH value of the cesium secondary extraction is 12-12.5.

[0020] Preferably, the pH value of the rubidium extraction is 12.5-13.

[0021] The second technical solution of the present invention is to provide lithium carbonate, cesium carbonate and rubidium carbonate recovered according to the above method.

[0022] The technical principles of the present invention are as follows:

[0023] Similar solutions in the prior art generally use sulfuric acid to neutralize the lithium mother liquor from lithium ore extraction to a pH below 7 to remove CO3 2- , circulate concentrated crystal Na2SO4 (carrying lithium loss 0.5-1%) and increase the lithium ion concentration, and then carry out secondary lithium precipitation of the lithium-containing concentrate. Since the content of Na2SO4 and other impurities is significantly higher than that of the primary lithium precipitation, the lithium carbonate produced by the secondary lithium precipitation is generally industrial-grade lithium carbonate, which still needs carbonization reaction to prepare battery-grade lithium carbonate. The ternary synergistic stripping system designed by the present invention can solve this problem, connect with the traditional carbonization process, and prepare battery-grade lithium carbonate in one step.

[0024] The stripping process designed by the present invention is different from the traditional acid stripping. It adopts water and gas stripping, does not consume acid, has a stable system, has little pollution, and the organic phase of this process method can be directly recycled without consuming alkali. ZK960 in the present invention is an extractant designed for the separation of rubidium and cesium in the reaction step, and the rubidium and cesium in the raffinate can be extracted separately by adjusting the concentration of the extractant.

[0025] The beneficial technical effects of the present invention are as follows:

[0026] The present invention solves the problems of the traditional lithium ore extraction scheme, such as complicated steps (such as the need for multiple lithium precipitations), high cost, the need to add a large amount of sodium carbonate and acid-base solutions, high pollution, and the easy generation of a large amount of acid-base waste discharge. The present invention aims at the problem that the three elements are difficult to separate and the purity is low when extracting lithium, rubidium and cesium from lithium ore, and provides a targeted process method for continuous extraction of lithium, rubidium and cesium. Through the innovation of the process method, lithium, rubidium and cesium can be extracted from the lithium, rubidium and cesium solution at the same time and the purity and recovery rate can be guaranteed, and lithium carbonate, rubidium carbonate and cesium carbonate can be finally obtained. The process of the present invention is short, the extraction efficiency is good, energy-saving, and the economic benefits are high. It can greatly reduce pollution and cost, and is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is a flow chart of the preparation process of Example 1 of the present invention. DETAILED DESCRIPTION

[0029] Now, various exemplary embodiments of the present invention are described in detail, and this detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics and embodiments of the present invention. It should be understood that the terms described in the present invention are only for describing specific embodiments and are not used to limit the present invention.

[0030] In addition, for the numerical range in the present invention, it is understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0031] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the invention pertains. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention.

[0032] The words “include,” “including,” “have,” “contain,” etc. used in the present invention are open-ended terms, meaning including but not limited to.

[0033] The kerosene used in the following examples and comparative examples of the present invention is 260# sulfonated kerosene.

[0034] All raw materials used in the following examples and comparative examples of the present invention are commercially available products.

[0035] The extraction in the following embodiments and comparative examples of the present invention is carried out by using a centrifugal extractor for five-stage continuous extraction.

[0036] In the following embodiments and comparative examples of the present invention, CO2 is continuously and excessively introduced during the stripping operation.

[0037] Figure 1 This is a flow chart of the preparation process of Example 1 of the present invention.

[0038] Example 1

[0039] A method for recovering lithium, rubidium and cesium from lithium ore:

[0040] Step 1, calcining spodumene at 1080°C for 2h, mixing it with sulfuric acid (the concentration of sulfuric acid is 98wt%) at a mass ratio of 5:2, and roasting it at 280°C for 2h to obtain a secondary roasting product, then leaching it with water at a liquid-to-solid ratio of 2:1 at 80°C for 0.5h, and filtering;

[0041] Step 2: add quicklime to the filtrate to adjust the pH value to 10, then add sodium carbonate to remove impurities such as calcium and magnesium, filter after precipitation, and obtain a lithium-rubidium-cesium solution;

[0042] Step 3: Add a lithium extractant (a tributyl phosphate kerosene solution with a tributyl phosphate concentration of 10 wt%) to the filtrate obtained in step 2 for extraction (the mass ratio of the filtrate to the lithium extractant is 9:1) to obtain a lithium extract and a raffinate, and pass the lithium extract, pure water and CO2 into a new ternary stripping system (the mass ratio of the lithium extract to pure water is 1:1) for stripping for 40 minutes to obtain a lithium bicarbonate solution and a blank organic phase, and fully pyrolyze to obtain battery-grade lithium carbonate;

[0043] Step 4: adding a cesium extractant (a tri(2,5-xylyl)phosphine kerosene solution having a tri(2,5-xylyl)phosphine concentration of 15 wt%) to the raffinate obtained in step 3, extracting at a pH of 12 (the mass ratio of the raffinate to the cesium extractant is 4:1) to obtain a cesium extract and a raffinate, passing the cesium extract, pure water and CO2 into a novel ternary stripping system (the mass ratio of the cesium extract to pure water is 1:2) for stripping for 40 min to obtain a cesium bicarbonate solution and a blank organic phase, and fully pyrolyzing to obtain cesium carbonate;

[0044] Step 5: Add a cesium extractant (a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 15wt%) to the raffinate obtained in step 4 for extraction (the mass ratio of the filtrate to the cesium extractant is 4:1) to obtain a cesium extract and a raffinate, adjust the pH of the raffinate to 13, and add a rubidium extractant (a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 25wt%) to extract (the mass ratio of the raffinate to the rubidium extractant is 3:1) to obtain a rubidium extract and a raffinate, pass the rubidium extract, pure water and CO2 into a new ternary stripping system (the mass ratio of the rubidium extract to pure water is 1:2) for stripping for 40min to obtain a rubidium bicarbonate solution and a blank organic phase, and fully pyrolyze to obtain rubidium carbonate.

[0045] Examples 2-4 are repeated tests according to the process of Example 1, and the samples are from different batches.

[0046] Comparative Example 1

[0047] A method for recovering lithium, rubidium and cesium from lithium ore:

[0048] Step 1, calcining spodumene at 1080°C for 2h, mixing it with sulfuric acid (the concentration of sulfuric acid is 98wt%) at a mass ratio of 5:2, and roasting it at 280°C for 2h to obtain a secondary roasting product, then leaching it with water at a liquid-to-solid ratio of 2:1 at 80°C for 0.5h, and filtering;

[0049] Step 2: add quicklime to the filtrate to adjust the pH value to 10, then add sodium carbonate to remove impurities such as calcium and magnesium, filter after precipitation, and obtain a lithium-rubidium-cesium solution;

[0050] Step 3: Add a lithium extractant (a tributyl phosphate kerosene solution with a tributyl phosphate concentration of 10 wt%) to the filtrate obtained in step 2 for extraction (the mass ratio of the filtrate to the lithium extractant is 9:1) to obtain a lithium extract and a raffinate, mix the lithium extract and sulfuric acid (the mass ratio of the lithium extract to sulfuric acid is 1:2) for back extraction for 40 min to obtain an aqueous solution, then add sodium carbonate (the mass ratio of the aqueous solution to sodium carbonate is 1:1) to obtain industrial-grade lithium carbonate, and carbonize at 600° C. for 2 h to obtain battery-grade lithium carbonate;

[0051] Step 4: adding a cesium extractant (a tri(2,5-xylyl)phosphine kerosene solution having a tri(2,5-xylyl)phosphine concentration of 15 wt%) to the raffinate obtained in step 3, extracting at a pH value of 12 (the mass ratio of the raffinate to the cesium extractant is 4:1) to obtain a cesium extract and a raffinate, mixing the cesium extract and sulfuric acid (the mass ratio of the cesium extract to sulfuric acid is 1:2) for stripping for 40 min to obtain an aqueous phase solution, and then adding sodium carbonate (the mass ratio of the aqueous phase solution to the sodium carbonate is 1:1) to obtain cesium carbonate;

[0052] Step 5: Add a cesium extractant (a tri(2,5-xylyl)phosphine kerosene solution having a tri(2,5-xylyl)phosphine concentration of 15 wt%) to the raffinate obtained in step 4 for extraction (the mass ratio of the filtrate to the cesium extractant is 4:1) to obtain a cesium extract and a raffinate, adjust the pH of the raffinate to 13, and add a rubidium extractant (a tri(2,5-xylyl)phosphine kerosene solution having a tri(2,5-xylyl)phosphine concentration of 25 wt%) to extract (the mass ratio of the raffinate to the rubidium extractant is 4:1) to obtain a rubidium extract and a raffinate, mix the rubidium extract and sulfuric acid (the mass ratio of the rubidium extract to sulfuric acid is 1:2) for stripping for 40 minutes to obtain an aqueous solution, add sodium carbonate (the mass ratio of the aqueous solution to sodium carbonate is 1:1), and evaporate and crystallize to obtain rubidium carbonate.

[0053] Comparative Examples 2-4 are repeated tests according to the process method of Comparative Example 1, and the sample batches correspond to the batch order of the embodiment.

[0054] Comparative Example 5

[0055] The only difference from Example 1 is that the lithium extractant is changed to a tributyl phosphate kerosene solution with a tributyl phosphate concentration of 15 wt%, the cesium extractant is changed to a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 10 wt%, and the rubidium extractant is changed to a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 20 wt%.

[0056] Comparative Example 6

[0057] The only difference from Example 1 is that the lithium extractant is changed to a tributyl phosphate kerosene solution with a tributyl phosphate concentration of 8 wt%, the cesium extractant is changed to a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 18 wt%, and the rubidium extractant is changed to a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 28 wt%.

[0058] Comparative Example 7

[0059] The only difference from Example 1 is that the lithium extractant is changed to a tributyl phosphate kerosene solution with a tributyl phosphate concentration of 13 wt%, the cesium extractant is changed to a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 13 wt%, and the rubidium extractant is changed to a tri(2,5-xylyl)phosphine kerosene solution with a tri(2,5-xylyl)phosphine concentration of 23 wt%.

[0060] The lithium rubidium cesium recovery rates of the embodiments and comparative examples are shown in Table 1.

[0061] Table 1

[0062]

[0063] Among them, the calculation formulas for lithium recovery rate, rubidium recovery rate and cesium recovery rate are:

[0064] Lithium recovery rate = lithium mass content in stripping solution / lithium mass content in lithium-containing rubidium-cesium solution * 100%

[0065] Rubidium recovery rate = rubidium mass content in stripping solution / rubidium mass content in lithium-containing rubidium-cesium solution * 100%

[0066] Cesium recovery rate = Cesium mass content in stripping solution / Cesium mass content in lithium-rubidium-cesium solution * 100%

[0067] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for recovering lithium, rubidium and cesium from lithium ore, characterized in that: Using a 10wt% tributyl phosphate kerosene solution as a lithium extractant, a 15wt% tri(2,5-xylyl)phosphine kerosene solution as a cesium extractant, and a 25wt% tri(2,5-xylyl)phosphine kerosene solution as a rubidium extractant, the lithium, cesium, and rubidium-containing solutions obtained by water leaching lithium ore are extracted in sequence to obtain lithium extract, cesium extract, and rubidium extract.

2. The method according to claim 1, characterized in that: The obtained lithium extract, cesium extract and rubidium extract are respectively stripped using water and stripping gas to obtain lithium bicarbonate, cesium bicarbonate and rubidium bicarbonate; the lithium bicarbonate, cesium bicarbonate and rubidium bicarbonate are respectively pyrolyzed to obtain lithium carbonate, cesium carbonate and rubidium carbonate; the stripping gas is CO2.

3. The method according to claim 2, characterized in that The method for recovering lithium rubidium cesium comprises the following steps: The lithium ore is primarily roasted to obtain a primary roasted product, which is then mixed with sulfuric acid, and then secondarily roasted to obtain a secondary roasted product, which is then leached in water to obtain a lithium-rubidium-cesium solution; adding a lithium extractant to the lithium-containing rubidium-cesium solution to perform lithium extraction to obtain a lithium extract and a raffinate 1, performing lithium stripping on the lithium extract to obtain a lithium bicarbonate solution, and performing pyrolysis to obtain lithium carbonate; adding a cesium extractant to the raffinate 1 to perform cesium extraction to obtain a cesium extract and a raffinate 2, performing cesium stripping on the cesium extract to obtain a cesium bicarbonate solution, and performing pyrolysis to obtain cesium carbonate; Adding a cesium extractant to the raffinate 2 to perform a cesium secondary extraction to obtain a cesium secondary extract and a raffinate 3; A rubidium extractant is added to the raffinate 3 to perform rubidium extraction to obtain a rubidium extract and a raffinate 4. The rubidium extract is stripped to obtain a rubidium bicarbonate solution, which is thermally decomposed to obtain rubidium carbonate.

4. The method according to claim 3, characterized in that The lithium ore is spodumene; the temperature of the initial roasting is 1070-1100°C and the time is 2h.

5. The method according to claim 3, characterized in that: The mass ratio of the primary roasting product to sulfuric acid is 5:2; the temperature of the secondary roasting is 280° C. and the time is 2 hours.

6. The method according to claim 3, characterized in that The pH value of the lithium extraction is 9-11.

7. The method according to claim 3, characterized in that The pH value of the cesium extraction is 12-12.5; the pH value of the cesium secondary extraction is 12-12.

5.

8. The method according to claim 3, characterized in that The pH value of the rubidium extraction is 12.5-13.

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