Sulfate-process lithium extraction method capable of recycling potassium

Abstract

The invention relates to the technical field of sulfate process lithium extraction, and particularly provides a sulfate process lithium extraction method for recycling potassium, which improves the lithium leaching rate and reduces the overall consumption of potassium.

Description

Technical Field

[0001] The invention relates to the technical field of lithium extraction by sulfate method, in particular to a method for extracting lithium by sulfate method with potassium recycling. Background Art

[0002] Lithium, as an important rare element that promotes the development of modernization construction and related industries such as science and technology, is one of the most promising new energy sources and strategic resources. It is widely used in many fields such as high-energy lithium batteries, rubber industry, aerospace, ceramics, lasers, medicine, welding, explosives, cement, smelting and new energy.

[0003] In the prior art, the methods for extracting lithium from ores mainly include sulfuric acid method, sulfate method, limestone method, etc. Among them, the sulfate method faces two problems in the process of extracting lithium:

[0004] On the one hand, the amount and ratio of additives added during ore roasting will affect the roasting temperature and the final lithium leaching rate. It is crucial to select a better ratio to improve the lithium recovery rate.

[0005] On the other hand, the additive contains a large amount of potassium salt, which is used to replace the lithium in the ore, making the originally insoluble lithium soluble. This causes a large amount of potassium to become solid waste along with the leaching residue, and the high price of potassium leads to a high cost of the sulfate method.

[0006] It is an urgent pursuit of technicians in this field to be able to recycle the potassium in the leaching residue, significantly reduce the consumption of potassium in the sulfate process, and significantly reduce costs.

[0007] In the prior art, there is no report on the method for leaching potassium from the above-mentioned slag.

[0008] In the field of potash fertilizer extraction, there are related reports claiming that the hydrothermal treatment of potassium feldspar at 280°C can achieve a potassium leaching rate of 96.4-99.3%. (Wu Yusheng, Yu Meng, Li Laishi, Wu Xiushi. Optimization of potassium extraction process from potassium feldspar based on response surface methodology. Journal of Shenyang University of Technology. 2023, 45(1): 36-42). However, since the structure of the leached residue is different from that of potassium feldspar, technicians in the field of lithium extraction have no motivation to directly apply the above method to potassium extraction from leached residue.

[0009] Based on the above problems, the technical solution of this application is formed in the hope of obtaining the optimal economic value. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide a method for extracting lithium from ore, which solves the problems existing in the prior art.

[0011] One of the purposes of the present invention is to provide a step for recycling potassium in leaching residue, thereby significantly reducing potassium consumption and reducing costs;

[0012] The second purpose of the present invention is to determine the optimal parameters of the roasting process to improve the yield of lithium.

[0013] The present invention discloses a method for extracting lithium using a sulfate process with potassium recycling, comprising the following steps:

[0014] S1, mixing a roasting aid with a spodumene concentrate raw material for roasting and transformation, wherein the roasting aid is a conventional additive of a sulfate process;

[0015] S2, adding water and / or sulfuric acid to the product after roasting and transformation in step S1 for leaching, and filtering; the filtrate is the leaching liquid, and the filter residue is the leaching residue;

[0016] S3, removing impurities from the leachate produced in step S2;

[0017] S4, the impurity removal product of step S3 is a lithium-containing solution, which can be subjected to conventional separation treatment to obtain a lithium product;

[0018] S5, recovering potassium from the leaching residue produced in step S2; the potassium recovery step comprises the following steps:

[0019] S51, mixing and stirring the leached residue, a calcium source and water, wherein the calcium source is selected from at least one of calcium oxide, hydroxide or salt;

[0020] S52, heating the mixture prepared in step S51 for reaction;

[0021] S53, adding water to the product obtained in step S52 to leach out, and filtering; the obtained filter residue is calcium residue, and the obtained filtrate is used for crystallization;

[0022] S54, crystallizing the filtrate obtained in step S53 to obtain potassium sulfate, which is reused in step S1 as a roasting aid.

[0023] Furthermore, in the step S1, the roasting aid is K 2 SO 4 In terms of the amount of substance, the roasting aid and the lithium ore raw material are mixed in the following proportions: K :n Li =1.4~1.86.

[0024] Furthermore, in terms of mass fraction, based on 100 parts of lithium ore, the roasting aid further comprises 5 to 10 parts of CaSO 4 , 5-15 parts NaSO 4 , 1 to 3 parts of CaO.

[0025] Furthermore, the lithium ore is at least one of spodumene, lepidolite, lithium aluminum ore, clay lithium ore and lithium bauxite.

[0026] Furthermore, the step S3 includes the following steps:

[0027] S31, add CaCO to the leaching solution 3 Adjust the pH to 6, and filter to obtain a first purified liquid and a first filter residue;

[0028] S32, adding NaOH to the first purified liquid obtained in step S31 to adjust the pH to 12, and filtering to obtain a second purified liquid and a second filter residue;

[0029] S33, adding Na to the second purified solution obtained in step S32 2 CO 3 , filtering to obtain a third purified liquid and a third filter residue, wherein the third purified liquid is used in the lithium precipitation step.

[0030] Preferably, in S2, the roasted transformation product of step S1 is ground to -100 mesh by mass fraction, and then leached in water or 0-10% sulfuric acid at room temperature and pressure or under heating and pressure, with a leaching time of 0-10 hours and a liquid-to-solid ratio of 2.5-6.

[0031] Furthermore, the S4 step is a conventional sulfate method lithium precipitation step.

[0032] Furthermore, the step S4 includes the following steps:

[0033] S41, concentrating the third purified liquid obtained in step S3 to a Li concentration of 15-30 g / L, adding a saturated sodium carbonate hot solution to precipitate lithium, and filtering to obtain industrial-grade lithium carbonate and lithium precipitation mother liquor;

[0034] S42, purifying the lithium carbonate obtained in step S41 by hydrogenation and pyrolysis to obtain battery-grade lithium carbonate;

[0035] The lithium precipitation mother liquor obtained in steps S43 and S41 is further concentrated and thermally separated to obtain potassium sulfate crystals; after filtration, the thermally separated liquid is further frozen to separate sodium sulfate crystals, and the potassium sulfate is reused in step S1 as a roasting aid.

[0036] Preferably, in step S5, the calcium source is calcium oxide and / or calcium hydroxide.

[0037] Preferably, in step S5, m is expressed in terms of mass fraction. 钙源 :m 浸出渣 The ratio is 1 to 1.5:1, wherein the mass of the calcium source is converted into the mass of calcium oxide.

[0038] Preferably, in step S5, the liquid-to-solid ratio is 7.5 to 10:1 by mass fraction.

[0039] Preferably, in step S52, the reaction temperature is 220-260° C. More preferably, in step S52, the reaction temperature is 240° C.

[0040] Preferably, in step S52, the reaction time is 4 to 6 hours.

[0041] Preferably, in step S53, the leaching time is 30 minutes.

[0042] Preferably, step S5 includes the following steps:

[0043] S51, mixing ingredients, mixing the leached residue, calcium oxide and / or calcium hydroxide, and water and stirring them evenly; in terms of mass fraction, m 钙源 :m 浸出渣 The liquid-to-solid ratio is 1.5:1, wherein the mass of the calcium source is converted into the mass of calcium oxide; in terms of mass fraction, the liquid-to-solid ratio is 10:1.

[0044] S52, heating replacement, the mixture prepared in S51 is heated for reaction, the reaction temperature is 240°C, and the reaction time is 6 hours;

[0045] S53, leaching, adding water to the product obtained in step S52 for leaching for 30 minutes;

[0046] S54, filtering the product after leaching in S53, taking the filtrate and crystallizing it using a conventional method to obtain potassium sulfate.

[0047] Preferably, step S5 includes the following steps:

[0048] S51, mix the ingredients, mix the leaching residue, calcium oxide and water and stir them evenly; in terms of mass fraction, m 钙源 :m 浸出渣 The liquid-to-solid ratio is 1.2:1, wherein the mass of the calcium source is converted into the mass of calcium oxide; in terms of mass fraction, the liquid-to-solid ratio is 7.5:1.

[0049] S52, heating replacement, the mixture prepared in S21 is heated for reaction, the reaction temperature is 240-260°C, and the reaction time is 5h;

[0050] S53, leaching, adding water to the product obtained in step S22 for leaching for 30 minutes, and potassium ions will dissolve in the water;

[0051] S54, filtering the product after leaching in S23, taking the filtrate and crystallizing it by conventional methods to obtain potassium sulfate.

[0052] The beneficial effects of the present invention are:

[0053] 1. Provides a sulfate method for extracting lithium with potassium recycling;

[0054] 2. Effectively reduce the overall consumption of potassium in the sulfate process and significantly reduce costs;

[0055] 3. The reaction conditions are mild. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Flow chart;

[0057] Figure 2 Flow chart of potassium recovery steps;

[0058] Figure 3 Flow chart of lithium deposition steps;

[0059] Figure 4 Flow chart of the impurity removal steps. DETAILED DESCRIPTION

[0060] The specific implementation modes of the present invention are further described below in conjunction with examples. The following examples are only used to more clearly illustrate the technical embodiments of the present invention and are not intended to limit the protection scope of the present invention.

[0061] Example 1

[0062] The present invention discloses a method for extracting lithium using a sulfate process with potassium recycling, comprising the following steps:

[0063] S1. Mix the roasting aid and the spodumene concentrate raw material for roasting and transformation. In terms of the amount of substance, the roasting aid and the spodumene concentrate raw material are mixed in the following proportions: K :n Li =1.4~1.86;

[0064] S2, adding water to the product after the roasting and transformation in step S1 to leach, and filtering; the filtrate is the leachate, and the filter residue is the leach residue; in terms of mass fraction, the roasting and transformation product in step S1 is ground to -100 mesh, and then leached in water at room temperature and pressure or under heating and pressure, the leaching time is 0 to 10 hours, and the liquid-solid ratio is 2.5 to 6;

[0065] S3, removing impurities from the leachate produced in step S2; comprising the following steps:

[0066] S31, add CaCO to the leaching solution 3 Adjust the pH to 6, and filter to obtain a first purified liquid and a first filter residue;

[0067] S32, adding NaOH to the first purified liquid obtained in step S31 to adjust the pH to 12, and filtering to obtain a second purified liquid and a second filter residue;

[0068] S33, adding Na to the second purified solution obtained in step S32 2 CO3 , filtering to obtain a third purified liquid and a third filter residue, wherein the third purified liquid is used in the lithium precipitation step.

[0069] S4, precipitating lithium on the impurity removal product of step S3, comprising the following steps:

[0070] S41, concentrating the third purified liquid obtained in step S3 to a Li concentration of 15-30 g / L, adding a saturated sodium carbonate hot solution to precipitate lithium, and filtering to obtain lithium carbonate and lithium precipitation mother liquor;

[0071] S42, purifying the lithium carbonate obtained in step S41 by hydrogenation and pyrolysis to obtain battery-grade lithium carbonate;

[0072] The lithium precipitation mother liquor obtained in steps S43 and S41 is further concentrated and thermally separated to obtain potassium sulfate crystals; after filtration, the thermally separated liquid is further frozen to separate sodium sulfate crystals, and the potassium sulfate is reused in step S1 as a roasting aid;

[0073] S5, recovering potassium from the leaching residue produced in step S2; the potassium recovery step comprises the following steps:

[0074] S51, mixing ingredients, mixing the leached residue, calcium oxide and / or calcium hydroxide, and water and stirring them evenly; in terms of mass fraction, m 钙源 :m 浸出渣 The liquid-to-solid ratio is 1.5:1, wherein the mass of the calcium source is converted into the mass of calcium oxide; in terms of mass fraction, the liquid-to-solid ratio is 7.5:1.

[0075] S52, heating replacement, the mixture prepared in S51 is heated for reaction, the reaction temperature is 240°C, and the reaction time is 6 hours;

[0076] S53, leaching, adding water to the product obtained in step S52 for leaching, the leaching time is 30 minutes, and the potassium ions will dissolve in the water;

[0077] S54, filtering the product after leaching in S53, taking the filtrate and crystallizing it by conventional methods to obtain potassium sulfate, and the potassium sulfate is reused in the step S1 as a roasting aid.

[0078] Embodiments 2 to 17

[0079] The difference between Examples 2 to 17 and Example 1 is that the condition parameters of step S1 are different. The parameters of each example are shown in Table 1 below:

[0080] Table 1 Parameters of the embodiment (Step S1)

[0081]

[0082]

[0083] This shows that the lithium leaching effect of Example 15 is the best.

[0084] Embodiments 18 to 31

[0085] The difference between Examples 18 to 31 and Example 15 is that the condition parameters of step S5 are different. The parameters of each example are shown in Table 2 below:

[0086] Table 2 Parameters of the embodiment (step S5)

[0087]

[0088]

[0089] In order to further illustrate the beneficial effects of the technical solution of the present invention, the following comparative examples are set:

[0090] Comparative Examples 1 to 3

[0091] The difference between Comparative Examples 1 to 3 and Example 1 is only that the parameters of step S1 are different, and the specific parameters are shown in Table 3 below:

[0092] Table 3 Comparative Example Parameters (S1 Step)

[0093]

[0094] By comparing Comparative Examples 1 to 3 with Examples 1 to 15, it can be seen that the selection of parameters in step S1 affects the leaching rate of lithium.

[0095] Comparative Examples 4 to 10

[0096] The difference between Comparative Examples 4 to 7 and Example 15 is only in the parameters; the difference between Comparative Examples 8 to 10 and Example 15 is that the roasting method is adopted; the specific parameters are shown in Table 4 below:

[0097] Table 4 Comparative example parameters

[0098]

[0099] Note: When the "liquid-to-solid ratio" in the above table is " / ", it means no water is added, and the temperature of step S2 in the "calcination method" is adjusted to the temperature in the table.

[0100] In order to further verify the beneficial effects of the present invention, the above-mentioned embodiments and comparative examples were leached according to the method described in step S5 of embodiment 1, and the data are shown in the following table 5:

[0101] Table 5 Leaching results data table

[0102]

[0103]

[0104] Analysis of the above results:

[0105] 1. By comparing Examples 18 to 31 with Comparative Examples 8 to 10, it can be seen that the leaching effect of the hydrothermal method is much higher than that of the roasting method.

[0106] 2. By comparing Examples 18 to 19 with Comparative Examples 4 to 5, it can be seen that the selection of the liquid-to-solid ratio affects the final leaching results.

[0107] 3. By comparing Example 19 with Comparative Example 6, it can be seen that the amount of calcium source added affects the final leaching result.

[0108] 4. By comparing the embodiment with comparative example 7, it can be seen that the selection of temperature affects the final leaching result.

[0109] 5. By comparing Examples 19 to 23, Example 27 and Example 29 with other examples, it can be seen that the coordination between the amount of calcium source added and the liquid-to-solid ratio can produce unexpected effects.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for extracting lithium from a sulfate solution with potassium recycling, characterized in that: The steps include: S1, mixing a roasting aid with a spodumene concentrate raw material for roasting and transformation, wherein the roasting aid is a conventional additive of a sulfate process; S2, adding water and / or sulfuric acid to the product after roasting and transformation in step S1 for leaching, and filtering; the filtrate is the leaching liquid, and the filter residue is the leaching residue; S3, removing impurities from the leachate produced in step S2; S4, the impurity removal product of step S3 is a lithium-containing solution, which can be subjected to conventional separation treatment to obtain a lithium product; S5, recovering potassium from the leaching residue produced in step S2; the potassium recovery step comprises the following steps: S51, mixing and stirring the leached residue, a calcium source and water, wherein the calcium source is selected from at least one of calcium oxide, hydroxide or salt; S52, heating the mixture prepared in step S51 for reaction; S53, adding water to the product obtained in step S52 to leach out, and filtering; the obtained filter residue is calcium residue, and the obtained filtrate is used for crystallization; S54, crystallizing the filtrate obtained in step S53 to obtain potassium sulfate, which is reused in step S1 as a roasting aid.

2. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: In the step S1, the roasting aid is K2SO4, and the roasting aid and the lithium ore raw material are mixed in the following proportions based on the amount of substance: K :n Li =1.4~1.

86.

3. The method for extracting lithium by sulfate process with potassium recycling according to claim 2, characterized in that: In terms of mass parts, based on 100 parts of lithium ore, the roasting aid also includes 5 to 10 parts of CaSO4, 5 to 15 parts of NaSO4, and 1 to 3 parts of CaO.

4. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: The S3 step includes the following steps: S31, adding CaCO3 to the leachate to adjust the pH to 6, and filtering to obtain a first purified liquid and a first filter residue; S32, adding NaOH to the first purified liquid obtained in step S31 to adjust the pH to 12, and filtering to obtain a second purified liquid and a second filter residue; S33. Add Na2CO3 to the second purified liquid obtained in step S32, and filter to obtain a third purified liquid and a third filter residue, wherein the third purified liquid is used in the lithium precipitation step.

5. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: The S4 step includes the following steps: S41, concentrating the third purified liquid obtained in step S3 to a Li concentration of 15-30 g / L, adding a saturated sodium carbonate hot solution to precipitate lithium, and filtering to obtain industrial-grade lithium carbonate and lithium precipitation mother liquor; S42, purifying the lithium carbonate obtained in step S41 by hydrogenation and pyrolysis to obtain battery-grade lithium carbonate; The lithium precipitation mother liquor obtained in steps S43 and S41 is further concentrated and thermally separated to obtain potassium sulfate crystals; after filtration, the thermally separated liquid is further frozen to separate sodium sulfate crystals, and the potassium sulfate is reused in step S1 as a roasting aid.

6. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: In step S5, the calcium source is calcium oxide and / or calcium hydroxide.

7. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: In step S5, m is expressed in terms of mass fraction. 钙源 :m 浸出渣 The ratio is 1 to 1.5:1, wherein the mass of the calcium source is converted into the mass of calcium oxide.

8. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: In step S5, the liquid-to-solid ratio is 7.5 to 10:1 by mass fraction.

9. The method for extracting lithium by sulfate process with potassium recycling according to claim 1, characterized in that: In step S52, the reaction temperature is 200-260°C.

10. The method for extracting lithium from a sulfate solution with potassium recycling according to claim 1, characterized in that: Step S5 includes the following steps: S51, mixing ingredients, mixing the leached residue, calcium oxide and / or calcium hydroxide, and water and stirring them evenly; in terms of mass fraction, m 钙源 :m 浸出渣 The ratio of liquid to solid is 1.5:1, where the mass of the calcium source is converted into the mass of calcium oxide; in terms of mass fraction, the liquid-to-solid ratio is 10:1; S52, heating replacement, the mixture prepared in S51 is heated for reaction, the reaction temperature is 240°C, and the reaction time is 6 hours; S53, leaching, adding water to the product obtained in step S52 for leaching, the leaching time is 30 minutes, and the potassium ions will dissolve in the water; S54, filtering the product after leaching in S53, and taking the filtrate and crystallizing it by conventional methods to obtain potassium sulfate; Or, step S5 includes the following steps: S51, mix the ingredients, mix the leaching residue, calcium oxide and water and stir them evenly; in terms of mass fraction, m 钙源 :m 浸出渣 The liquid-to-solid ratio is 1.2:1, wherein the mass of the calcium source is converted into the mass of calcium oxide; in terms of mass fraction, the liquid-to-solid ratio is 7.5:

1. S52, heating replacement, the mixture prepared in S21 is heated for reaction, the reaction temperature is 240-260°C, and the reaction time is 5h; S53, leaching, adding water to the product obtained in step S22 for leaching for 30 minutes, and potassium ions will dissolve in the water; S54, filtering the product after leaching in S23, taking the filtrate and crystallizing it by conventional methods to obtain potassium sulfate.

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