Method for reducing roasting temperature of lepidolite and cooperatively extracting lithium, rubidium, cesium and potassium

Abstract

The invention relates to a method for reducing the roasting temperature of lepidolite and cooperatively extracting lithium, rubidium, cesium and potassium. The method comprises the following steps: (1) pre-roasting a roasting additive; (2) uniformly mixing the pre-roasted roasting additive with lepidolite concentrate, and roasting to obtain roasted clinker; (3) the roasted clinker is subjected to water leaching, and a leaching solution containing lithium, rubidium, cesium and potassium is obtained; the roasting additive comprises ammonium sulfate, alkali metal sulfate and nitrate. The roasting additive generates a large amount of molten pyrosulfate in the pre-roasting process, the molten pyrosulfate can wrap lepidolite particles in the roasting process, the molten pyrosulfate and lepidolite are subjected to a liquid-solid reaction, the lepidolite structure is efficiently damaged, and therefore efficient sulfation of alkali metal elements is promoted. Water-soluble salts of lithium, rubidium, cesium and potassium are obtained in the roasting process, and efficient extraction can be achieved through simple water leaching by means of the water-soluble characteristic of the salts.

Description

Technical Field

[0001] The invention relates to the technical field of chemical metallurgy, and in particular to a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium. Background Art

[0002] Lepidolite is an important resource of lithium, rubidium, cesium and potassium. Currently, there are many methods for extracting metals from lepidolite by roasting, including acid method, alkali method, chlorination roasting and sulfate roasting. Due to its simple operation, low corrosion and high lithium extraction rate, sulfate roasting has gradually become one of the mainstream methods.

[0003] However, the existing sulfate roasting method has the problems of high roasting temperature (800-1100°C), resulting in high energy consumption, and it is difficult to extract rubidium, cesium and potassium at the same time. In CN117776231A, the mixture obtained by lithium mica and sodium sulfate, potassium sulfate, calcium sulfate and magnesium sulfate is roasted at 800-900°C, and a lithium-containing leaching solution is obtained after leaching. In CN110395751A, sodium sulfate and limestone are added as roasting auxiliary materials, and iron oxide powder is roasted at 700-1000°C as a roasting stabilizer, and a solution containing lithium sulfate is obtained after leaching. In CN113636579A, the mixture of lithium mica ore powder and sodium potassium sulfate, auxiliary agents and calcium carbonate are mixed and granulated in a certain proportion, and then roasted at 850-900°C in a rotary kiln, and filtered after water immersion to obtain a mother liquor containing lithium sulfate. Most of the above methods are roasted at a high temperature of 800-1100°C, which consumes a lot of energy, and the co-extraction of rubidium, cesium and potassium is not considered at the same time, resulting in the failure to fully extract and utilize high-value metal elements such as rubidium, cesium and potassium, resulting in a waste of lithium mica resources. Although the roasting temperature in CN118835103A is reduced to 650-750°C, and the extraction rate of lithium is also high, the roasting temperature is still high and is not reduced to below 600°C, and the synergistic extraction of rubidium, cesium and potassium from lithium mica is not involved.

[0004] The existing technology still has the problems of too high roasting temperature and insufficient utilization of elements such as rubidium, cesium and potassium. Therefore, it is urgent to develop a method with lower roasting temperature to achieve efficient extraction of lithium, rubidium, cesium and potassium from lithium mica. Summary of the invention

[0005] In order to solve the above technical problems, the present invention adopts a mixed salt composed of sulfate and nitrate as a roasting additive, and produces a large amount of molten pyrosulfate during the pre-roasting process, which can wrap the lithium mica particles during the roasting process, react with the lithium mica in a liquid-solid manner, and efficiently destroy the lithium mica structure, thereby promoting the efficient sulfation of alkali metal elements. Water-soluble salts of lithium, rubidium, cesium and potassium are obtained during the roasting process, and the water-soluble characteristics of these salts are utilized to achieve efficient extraction through simple water immersion.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium, the method comprising the following steps:

[0008] (1) pre-baking the calcination additive;

[0009] (2) roasting the pre-roasted calcination additive and the lepidolite concentrate after uniform mixing to obtain a roasted clinker;

[0010] (3) leaching the roasted clinker in water to obtain a leaching solution containing lithium, rubidium, cesium and potassium;

[0011] The roasting additives include ammonium sulfate, alkali metal sulfates and nitrates.

[0012] The present invention pre-baks the calcination additive, and the ammonium sulfate in the calcination additive reacts with sulfate to generate corresponding pyrosulfate after decomposition, and the molten pyrosulfate reacts with the lithium mica in the calcination process. In addition, the ammonium sulfate and nitrate will produce ammonia, nitrogen dioxide, sulfur dioxide and other gases in the calcination process, part of which can react with the lithium mica in a gas-solid manner, and part of which can make the material loose and porous to improve the reaction efficiency. The three components in the calcination additive act synergistically to improve the reaction efficiency of the alkali metal elements in the lithium mica, so that the lithium, rubidium, cesium and potassium elements in the lithium mica can be fully extracted by water immersion.

[0013] As a preferred technical solution of the present invention, the alkali metal sulfate includes potassium sulfate and / or sodium sulfate.

[0014] Preferably, the nitrate comprises potassium nitrate and / or sodium nitrate.

[0015] Preferably, the mass ratio of the ammonium sulfate, the alkali metal sulfate and the nitrate is 1:1:(0.1-1), for example, it can be 1:1:0.1, 1:1:0.2, 1:1:0.4, 1:1:0.6, 1:1:0.8 or 1:1:1, etc.

[0016] The introduction of nitrate into the roasting additive of the present invention can greatly reduce the eutectic point of the system and improve the efficiency of the reaction between the roasting additive and lepidolite.

[0017] As a preferred technical solution of the present invention, the pre-calcination temperature in step (1) is 400-500°C, for example, it can be 400°C, 420°C, 440°C, 460°C, 480°C or 500°C.

[0018] As a preferred technical solution of the present invention, the pre-calcination time in step (1) is 10-30 min, for example, it can be 10 min, 15 min, 20 min, 22 min, 25 min or 30 min.

[0019] The present invention generates molten pyrosulfate in the calcination additive through a pre-calcination process. The pyrosulfate can react with the lithium element of the lepidolite to generate soluble lithium sulfate, thereby promoting the leaching of lithium. The pyrosulfate is an excellent mineral structure destroyer, which can more effectively destroy the aluminosilicate structure of the lepidolite at high temperature and promote the leaching of rubidium, cesium and potassium elements.

[0020] As a preferred technical solution of the present invention, the lepidolite concentrate in step (2) is obtained by pre-treating the lepidolite ore raw material.

[0021] Preferably, the pretreatment may adopt any lepidolite pretreatment method known to those skilled in the art, such as ball milling, flotation, etc.

[0022] As a preferred technical solution of the present invention, the mass ratio of the roasting additive and the lithium mica concentrate in step (2) is (1-3):1, for example, it can be 1:1, 1.5:1, 1.8:1, 2:1, 2.5:1 or 3:1, etc.

[0023] As a preferred technical solution of the present invention, the calcination temperature in step (2) is 400-600°C, for example, it can be 400°C, 420°C, 450°C, 500°C, 550°C or 600°C, preferably 450-600°C.

[0024] Preferably, the calcination time in step (2) is 30-180 min, for example, 30 min, 40 min, 60 min, 80 min, 100 min, 150 min or 180 min.

[0025] The present invention reduces the eutectic temperature of the system by introducing nitrates, thereby promoting the occurrence of solid-liquid reaction, reducing the roasting temperature and improving the reaction efficiency.

[0026] As a preferred technical solution of the present invention, the water immersion temperature in step (3) is 25-90°C, for example, it can be 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 70°C, 80°C or 90°C.

[0027] Preferably, the immersion time in step (3) is 15-180 min, for example, it can be 15 min, 30 min, 40 min, 60 min, 80 min, 100 min, 150 min or 180 min.

[0028] As a preferred technical solution of the present invention, stirring is performed while immersing in water in step (3).

[0029] As a preferred technical solution of the present invention, the method comprises the following steps:

[0030] (1) pre-baking a baking additive at 400-500° C. for 10-30 min; the baking additive comprises ammonium sulfate, alkali metal sulfate and nitrate; the alkali metal sulfate comprises potassium sulfate and / or sodium sulfate; the nitrate comprises potassium nitrate and / or sodium nitrate; the mass ratio of the ammonium sulfate, alkali metal sulfate and nitrate is 1:1:(0.1-1);

[0031] (2) uniformly mixing the pre-baked calcination additive and the lepidolite concentrate in a mass ratio of (1-3):1 and then calcining the mixture, wherein the calcination temperature is 400-600° C. and the calcination time is 30-180 min to obtain a calcined clinker;

[0032] (3) Soaking the roasted clinker in water at 25-90° C. for 15-180 min while stirring to obtain a leaching solution containing lithium, rubidium, cesium and potassium.

[0033] Compared with the prior art, the present invention has at least the following beneficial effects:

[0034] (1) The present invention reduces the roasting temperature to 400-600°C, which is much lower than the 800-1100°C of the prior art, thereby greatly reducing the energy consumption of extracting lithium, rubidium, cesium and potassium from lepidolite.

[0035] (2) The present invention can simultaneously extract lithium, rubidium, cesium and potassium elements, and various metal elements can be fully leached and utilized, thereby improving the utilization rate of lithium mica. Under the optimal conditions, the lithium leaching rate can reach 91.7%, the rubidium leaching rate can reach 87.6%, the cesium leaching rate can reach 86.4%, and the potassium leaching rate can reach 72.3%. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is the XRD spectrum of the calcined additive after pre-calcination in Example 1 of the present invention.

[0037] Figure 2 It is a trend diagram of the leaching rate of lithium, rubidium, cesium and potassium of different types of roasting additives of the present invention.

[0038] Figure 3 It is a trend diagram of the leaching rates of lithium, rubidium, cesium and potassium of the lepidolite of the present invention and roasting additives of different qualities.

[0039] Figure 4 It is a trend diagram of the leaching rates of lithium, rubidium, cesium and potassium at different roasting temperatures of the present invention.

[0040] Figure 5 It is a trend diagram of the leaching rates of lithium, rubidium, cesium and potassium at different roasting times of the present invention.

[0041] Figure 6 It is a trend diagram of the leaching rates of lithium, rubidium, cesium and potassium at different water immersion temperatures of the present invention.

[0042] Figure 7 It is a leaching rate trend diagram of lithium, rubidium, cesium and potassium at different water immersion times of the present invention. DETAILED DESCRIPTION

[0043] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0044] The raw materials used in the following examples are all from common commercially available products, and the devices or equipment used are all purchased from conventional market sales channels.

[0045] Example 1

[0046] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium, the method comprising the following steps:

[0047] (1) pre-calcining a calcining additive (a mixture of ammonium sulfate: sodium sulfate: sodium nitrate in a mass ratio of 1:1:0.5) at 500°C for 10 min;

[0048] (2) the pre-baked calcination additive and the lepidolite concentrate are uniformly mixed in a mass ratio of 2:1 and then calcined at a temperature of 500° C. and a calcination time of 120 min to obtain a calcined clinker;

[0049] (3) The roasted clinker was stirred and leached at 90°C and 800 rpm for 60 min, and a leaching solution containing lithium, rubidium, cesium and potassium was obtained by suction filtration. The concentrations of lithium, rubidium, cesium and potassium ions in the leaching solution were determined by ICP-OES and the leaching rate was analyzed. Figure 1 The figure shows the XRD spectrum of the calcined additive in this example after pre-calcination, which proves the formation of pyrosulfate.

[0050] Example 2

[0051] This embodiment provides a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium. The method is the same as Example 1 except that the composition of the roasting additive is: the mass ratio of ammonium sulfate: sodium sulfate: potassium nitrate is 1:1:0.1.

[0052] Example 3

[0053] This embodiment provides a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium. The method is the same as Example 1 except that the composition of the roasting additive is: the mass ratio of ammonium sulfate: sodium sulfate: potassium nitrate is 1:1:1.

[0054] Example 4

[0055] This embodiment provides a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the mass ratio of the roasting additive to the lepidolite concentrate is 1:1.

[0056] Example 5

[0057] This embodiment provides a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the mass ratio of the roasting additive to the lepidolite concentrate is 3:1.

[0058] Example 6

[0059] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination temperature is 400°C.

[0060] Example 7

[0061] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination temperature is 450°C.

[0062] Example 8

[0063] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium. The method is the same as that of embodiment 2 except that the calcination temperature is 600°C.

[0064] Example 9

[0065] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination time is 30 minutes.

[0066] Example 10

[0067] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination time is 180 minutes.

[0068] Embodiment 11

[0069] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the water immersion temperature is 25°C.

[0070] Example 12

[0071] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the water immersion temperature is 60°C.

[0072] Embodiment 13

[0073] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the immersion time is 15 minutes.

[0074] Embodiment 14

[0075] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the immersion time is 180 minutes.

[0076] Embodiment 15

[0077] This embodiment provides a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium. The method is the same as Example 2 except that the composition of the roasting additive is: the mass ratio of ammonium sulfate: sodium sulfate: potassium nitrate is 1:1:0.05.

[0078] Example 16

[0079] This embodiment provides a method for reducing the roasting temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium. The composition of the roasting additive is as follows: the mass ratio of ammonium sulfate: sodium sulfate: potassium nitrate is 1:1:1.5, and the rest is the same as that of Example 2.

[0080] Embodiment 17

[0081] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination temperature is 350°C.

[0082] Embodiment 18

[0083] This embodiment provides a method for synergistically extracting lithium, rubidium and cesium potassium by roasting lepidolite. The method is the same as that of Embodiment 2 except that the roasting temperature is 700°C.

[0084] Embodiment 19

[0085] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination time is 15 minutes.

[0086] Embodiment 20

[0087] This embodiment provides a method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium, and cesium potassium. The method is the same as that of Embodiment 2 except that the calcination time is 200 minutes.

[0088] Comparative Example 1

[0089] This comparative example provides a method for synergistically extracting lithium, rubidium, and cesium potassium by roasting lepidolite. The method is the same as Example 1 except that the roasting additive is not pre-roasted.

[0090] Comparative Example 2

[0091] This comparative example provides a method for synergistically extracting lithium, rubidium and cesium potassium by roasting lepidolite. The method is the same as Example 1 except that the composition of the roasting additive is that the mass ratio of ammonium sulfate to sodium sulfate is 1:1.

[0092] Comparative Example 3

[0093] This comparative example provides a method for synergistically extracting lithium, rubidium and cesium potassium by roasting lepidolite. The method is the same as Example 1 except that the composition of the roasting additive is that the mass ratio of sodium pyrosulfate to sodium nitrate is 2:0.5.

[0094] The test results are shown in Table 1 and Figure 2-7 shown.

[0095] Table 1

[0096]

[0097]

[0098] The test results show that:

[0099] (1) It can be seen from Examples 1 to 14 that the present invention produces a large amount of molten pyrosulfate during the pre-baking process of the baking additive, which can achieve efficient leaching of lithium, rubidium, cesium and potassium elements in lepidolite. The synergistic effect of sulfate and nitrate promotes the leaching of lithium, rubidium, cesium and potassium elements inside lepidolite. The lithium leaching rate is above 68%, the rubidium leaching rate is above 63%, the cesium leaching rate is above 50%, and the potassium leaching rate is above 45%. The best embodiment has a lithium leaching rate of 91.7%, a rubidium leaching rate of 87.6%, a cesium leaching rate of 86.4%, and a potassium leaching rate of 72.3%.

[0100] (2) It can be seen from Example 2 and Examples 15-16 that the present invention can achieve better leaching effect by further optimizing the composition of the roasting additive. When the amount of nitrate added in the roasting additive is too little, the lithium leaching rate decreases from 90.6% to 90.2%, the rubidium leaching rate decreases from 83.9% to 81.3%, the cesium leaching rate decreases from 80.8% to 78.5%, and the potassium leaching rate decreases from 70.3% to 66.9%. When the amount of nitrate added in the roasting additive is too much, the lithium leaching rate decreases from 90.6% to 89.5%, the rubidium leaching rate decreases from 83.9% to 79.3%, the cesium leaching rate decreases from 80.8% to 78.9%, and the potassium leaching rate increases from 70.3 to 78.5%.

[0101] (3) It can be seen from Example 2 and Examples 17-20 that the present invention can further improve the efficiency of the reaction of lithium elements and the like during the roasting process by further optimizing the roasting temperature and time, and reduce the energy consumption of roasting while maintaining a high leaching rate of lithium, rubidium, cesium and potassium elements.

[0102] (4) It can be seen from Example 1 and Comparative Examples 1-3 that the present invention generates molten pyrosulfate in the pre-baking process of the calcination additive to promote the leaching of metal elements in lepidolite, and when no pre-baking is performed, the leaching rates of lithium, rubidium, cesium and potassium elements are greatly reduced. When no nitrate is added to the calcination additive in Comparative Example 2, the nitrate cannot synergize with the sulfate to reduce the eutectic point of the system, resulting in a reduction in the reaction efficiency of each element, the lithium leaching rate is reduced from 91.7% to 73.9%, the rubidium leaching rate is reduced from 87.6% to 71.1%, the cesium leaching rate is reduced from 86.4% to 63.3%, and the potassium leaching rate is reduced from 72.3% to 52.6%. When pyrosulfate and nitrate are directly added as calcination additives in Comparative Example 3, due to the lack of gas activation generated by the decomposition of ammonium sulfate, the leaching rate of metal elements in lepidolite decreases, and the process economy is greatly reduced due to the expensive price of pyrosulfate.

[0103] In summary, the present invention generates a large amount of molten pyrosulfate during the pre-baking process of the calcination additive, thereby improving the leaching rate of lithium, rubidium, cesium and potassium elements in lepidolite. The synergistic effect of sulfate and nitrate promotes the leaching of lithium, rubidium, cesium and potassium elements in lepidolite, thereby achieving the technical effect of efficiently extracting lithium, rubidium, cesium and potassium elements from lepidolite under low temperature conditions.

[0104] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for reducing the calcination temperature of lepidolite and synergistically extracting lithium, rubidium and cesium potassium, characterized in that: The method comprises the following steps: (1) pre-calcining the calcination additive; (2) roasting the pre-roasted calcination additive and the lepidolite concentrate after uniform mixing to obtain a roasted clinker; (3) leaching the roasted clinker in water to obtain a leaching solution containing lithium, rubidium, cesium and potassium; The roasting additives include ammonium sulfate, alkali metal sulfates and nitrates.

2. The method according to claim 1, characterized in that The alkali metal sulfate includes potassium sulfate and / or sodium sulfate; Preferably, the nitrate comprises potassium nitrate and / or sodium nitrate; Preferably, the mass ratio of the ammonium sulfate, the alkali metal sulfate and the nitrate is 1:1:(0.1-1).

3. The method according to claim 1 or 2, characterized in that: The pre-baking temperature in step (1) is 400-500°C.

4. The method according to any one of claims 1 to 3, characterized in that: The pre-baking time in step (1) is 10-30 minutes.

5. The method according to any one of claims 1 to 4, characterized in that: The lithium mica concentrate in step (2) is obtained by pre-treating the lithium mica ore raw material.

6. The method according to any one of claims 1 to 5, characterized in that: The mass ratio of the roasting additive and the lithium mica concentrate in step (2) is (1-3):

1.

7. The method according to any one of claims 1 to 6, characterized in that: The calcination temperature in step (2) is 400-600° C., preferably 450-600° C.; Preferably, the calcination time in step (2) is 30-180 min.

8. The method according to any one of claims 1 to 7, characterized in that: The water immersion temperature in step (3) is 25-90° C. Preferably, the immersion time in step (3) is 15-180 min.

9. The method according to any one of claims 1 to 8, characterized in that: The step (3) is performed while stirring the mixture while immersing it in water.

10. The method according to any one of claims 1 to 9, characterized in that: The method comprises the following steps: (1) pre-baking a baking additive at 400-500° C. for 10-30 min; the baking additive comprises ammonium sulfate, alkali metal sulfate and nitrate; the alkali metal sulfate comprises potassium sulfate and / or sodium sulfate; the nitrate comprises potassium nitrate and / or sodium nitrate; the mass ratio of the ammonium sulfate, alkali metal sulfate and nitrate is 1:1:(0.1-1); (2) the pre-baked calcination additive and the lepidolite concentrate are uniformly mixed in a mass ratio of (1-3):1 and then calcined at a temperature of 400-600° C. and a calcination time of 30-180 min; Obtaining roasted clinker; (3) Soaking the roasted clinker in water at 25-90° C. for 15-180 min while stirring to obtain a leaching solution containing lithium, rubidium, cesium and potassium.

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