A short process for lithium extraction from lithium clay ores

Abstract

The application discloses a short-process lithium extraction method of lithium clay ore, and belongs to the technical field of lithium extraction. 3+ The main component of the alunite formed in the form of alum is XAl3(SO4)2(OH)2 (X is Na or K). The alunite is insoluble in water and slightly soluble in sulfuric acid, has good crystallinity, and has less adsorption and entrainment of free ions, and almost no entrainment of lithium. The application fully utilizes the characteristics of the alunite, converts Al 3+ into alunite precipitation which is dissolved from the lithium ore by acid, reduces the Al / Li ratio of the leaching solution, and finally collects lithium in the form of lithium carbonate by using the calcium-magnesium resin to adsorb a small amount of calcium and magnesium ions.

Description

Technical Field

[0001] This disclosure pertains to the field of metallurgy, and particularly relates to a short-process lithium extraction method for lithium clay ore. Background Technology

[0002] Lithium resources have wide applications in lithium-ion batteries and related fields. With the rapid development of the lithium-ion battery industry, the demand for lithium resources in industrial production is growing faster and faster, and in recent years there has even been a situation where the supply of lithium raw materials cannot meet the demand.

[0003] my country's lithium resources are mainly found in two forms: salt lakes and lithium mines. The lithium grade varies significantly depending on the type of lithium mine and the geographical location of the deposit. Generally speaking, lithium in mainstream lithium mines is mainly found in spodumene, lepidolite, and lithium clay.

[0004] Among them, spodumene and lepidolite have slightly higher lithium grades, with flotation concentrates typically reaching around 4% and 2% lithium grades, respectively. In contrast, lithium clay rarely achieves a lithium grade above 0.5%. Considering the limited reserves of high-grade lithium resources, attention should be focused on raw materials with slightly lower lithium grades, such as lithium clay.

[0005] Lithium clay contains abundant Al and Si elements. To efficiently extract lithium from it, traditional acid leaching methods often also leach out large amounts of aluminum, resulting in a high Al / Li ratio in the leachate. However, to recover lithium from the leachate into high-purity lithium salts, Al must first be removed. Traditional methods involve adjusting the solution pH to precipitate Al impurities as Al(OH)3. However, Al(OH)3, as a flocculent substance, carries away a significant amount of Li. + Adsorption (exceeding 10%) significantly reduces the overall lithium recovery rate.

[0006] Therefore, it is necessary to develop a highly selective lithium extraction method for low-grade lithium ore, which results in a low Al / Li ratio in the leachate, avoids lithium loss due to impurity removal, and thus improves the overall lithium recovery rate. Summary of the Invention

[0007] Based on this, the purpose of this disclosure is to provide a method for recovering lithium resources from low-lithium-grade lithium clay ore, which mainly achieves selective lithium extraction from lithium clay minerals, thereby reducing the Al / Li ratio of the leachate and improving the overall lithium yield.

[0008] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0009] Calcining lithium clay ore yields calcined material;

[0010] The aging material is dissolved in pure water with concentrated sulfuric acid and alkali metal sulfate, and a hydrothermal reaction is carried out. After filtration, a leachate is obtained.

[0011] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0012] A saturated sodium carbonate solution was added to the impurity removal solution, and the mixture was filtered to obtain lithium carbonate filter residue.

[0013] This disclosure is achieved through pressure leaching, mainly by improving the lithium leaching rate while simultaneously increasing the Al content. 3+ The alunite formed by precipitation in the form of alum is mainly composed of XAl3(SO4)2(OH)2, where X is an alkali metal element. This alunite is insoluble in water, slightly soluble in sulfuric acid, and has good crystallinity. Higher crystallinity results in more regular particle shapes and less adsorption and entrainment of free ions, thus almost eliminating lithium entrainment. This disclosed technology fully utilizes this characteristic of alunite to remove Al from lithium ore dissolved by acid. 3+ The alum stone is converted into alum stone precipitate. After the reaction, the pH of the solution is above 3, so the alum stone will not dissolve, which reduces the Al / Li ratio of the leachate. At the same time, a small amount of calcium and magnesium ions are adsorbed by calcium and magnesium removal resin, and finally lithium is collected in the form of lithium carbonate.

[0014] Preferably, the calcination temperature of the lithium clay ore is 500-1000℃. Calcination at this temperature causes the lithium clay ore to undergo a dehydroxylation phase transition, thereby breaking the complex bonds between other elements and lithium in the lithium clay ore. After heat treatment, lithium exists in the form of Li2O.

[0015] Preferably, the calcination time of the lithium clay ore is 1 to 12 hours. If the calcination time is too short, the lithium clay ore cannot completely undergo the dehydroxylation phase transition. If the calcination time is too long, it will not have a beneficial effect on the dehydroxylation phase transition and will instead increase the cost.

[0016] Preferably, the mass ratio of the aging material to the concentrated sulfuric acid is 1:0.1 to 1. If the amount of sulfuric acid is too low, it will not be able to dissolve the lithium element in the aging material. If the amount of sulfuric acid is too high, it will not be beneficial to the lithium dissolution effect, but will instead increase the cost.

[0017] Preferably, the mass ratio of the calcined material to the alkali metal sulfate is 1:0.1 to 2.5. If the alkali metal sulfate is too little, it will not provide enough alkali metal ions to form alunite; if the alkali metal sulfate is too much, it will not have a beneficial effect and will instead be too costly. Among them, lithium clay usually contains varying amounts of sodium and potassium elements, which can be utilized. The amount of alkali metal sulfate should be determined according to the sodium and potassium content in the raw material.

[0018] Preferably, the alkali metal sulfate is at least one of potassium sulfate and sodium sulfate. In alunite formed from sodium sulfate or potassium sulfate, the Na and K sites are located in the interlayer positions, which can support the crystal structure of alunite, while Li...+ With its small radius, it cannot contain Na and K sites, and therefore there is no lithium alunite phase, which reduces the entrainment of lithium ions and improves the lithium yield.

[0019] Preferably, the concentrated sulfuric acid has a mass concentration of 98%.

[0020] Preferably, the liquid-to-solid ratio of the hydrothermal reaction is 2-6:1 (ml:g), wherein the liquid is the total volume of the concentrated sulfuric acid and the pure water, and the solid is the total mass of the calcined material and the alkali metal sulfate. If the liquid-to-solid ratio is too low, the acidity of the solution will be too high, which will place high demands on the equipment. If the liquid-to-solid ratio is too high, the acidity will be too low, which may lead to a decrease in the lithium leaching rate.

[0021] Preferably, the temperature of the hydrothermal reaction is 100–230°C, and the hydrothermal reaction promotes the Al... 3+ The alum formation reaction only produces a significant promoting effect when the temperature reaches above 100℃. In the temperature range of 100-230℃, the higher the temperature, the faster the reaction rate and the shorter the reaction time. However, when the temperature is above 230℃, the increase in the alum formation reaction rate is weak, and further increasing the temperature will only increase energy consumption and cost.

[0022] Preferably, the hydrothermal reaction time is 1–12 hours. If the reaction time is less than 1 hour, it will lead to Al 3+ The conversion rate to alum is relatively low. If the reaction time is too long, it will not help to improve the conversion rate, but will instead increase energy consumption costs.

[0023] Preferably, the pressure of the hydrothermal reaction is the saturated vapor pressure of water at the corresponding reaction temperature, which is 0.1 to 2.8 MPa. Reacting under high pressure can improve the crystallinity of alunite, further reduce the entrainment of lithium ions, and improve the lithium yield.

[0024] Preferably, the amount of saturated sodium carbonate solution added is 1 to 3 times that of the impurity removal solution, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na. Increasing the concentration of carbonate ions can precipitate as much lithium as possible, thereby improving the lithium yield.

[0025] Preferably, the impurity removal solution is heated to 90-100°C, and then the saturated sodium carbonate solution at the same temperature as the impurity removal solution is added; increasing the temperature can reduce the solubility of lithium carbonate and increase the lithium yield.

[0026] Preferably, after adding saturated sodium carbonate solution to the impurity removal solution, the reaction time is 0.1 to 3 hours. If the reaction time is too short, lithium carbonate particles with good crystallinity cannot be obtained. If the reaction time is too long, the beneficial effect is limited, but the energy consumption cost is high.

[0027] Preferably, a saturated sodium carbonate solution is added to the impurity removal solution, and the mixture is filtered while hot after the reaction. Hot filtration can reduce lithium loss and improve lithium recovery rate.

[0028] Preferably, the lithium carbonate filter residue is dried.

[0029] Preferably, the drying temperature is 60-120℃, the drying time is 3-12h, the lower limit of the drying temperature is 60℃, which can ensure the evaporation of moisture. If the temperature is lower than this, the drying effect cannot be achieved. The upper limit of the drying temperature is 120℃, which may cause the dehydration to be too fast, the particle structure to be destroyed, and the product performance to be unsatisfactory. Attached Figure Description

[0030] Figure 1 The images show the leaching residue described in Example 1, the leaching residue described in Comparative Example 1, and the XRD pattern of the lithium clay ore described in Example 1. Detailed Implementation

[0031] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0032] Lithium clay ore is calcined at 500-1000℃ for 1-12 hours to obtain calcined material;

[0033] The aging material is dissolved in pure water with 98% concentrated sulfuric acid and an alkali metal sulfate, and reacted at 100-230℃ for 1-12 hours. The reaction pressure is the saturated vapor pressure of water at this temperature. The liquid-to-solid ratio is 2-6:1 (ml:g), wherein the liquid is the total volume of the concentrated sulfuric acid and the pure water, and the solid is the total mass of the aging material and the alkali metal sulfate. The mass ratio of the aging material to the concentrated sulfuric acid is 1:0.1-1, and the mass ratio of the aging material to the alkali metal sulfate is 1:0.1-2.5. The alkali metal sulfate is at least one of potassium sulfate and sodium sulfate. The leachate is obtained by hot filtration.

[0034] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0035] The impurity removal solution is heated to 90-100℃, and a saturated sodium carbonate solution at the same temperature as the impurity removal solution is added. The reaction is carried out for 0.1-12 hours. After hot filtration, lithium carbonate filter residue is obtained and dried at a temperature of 60-120℃ for 3-12 hours. The amount of saturated sodium carbonate solution added is 1-3 times that of the impurity removal solution. The impurity removal solution is calculated based on the molar amount of Li, and the saturated sodium carbonate solution is calculated based on the molar amount of Na.

[0036] Example 1

[0037] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0038] Take 1 kg of lithium clay ore powder and calcine it at 500℃ for 12 hours to obtain calcined material;

[0039] The calcined material, 100g of 98% concentrated sulfuric acid, and 100g of sodium sulfate were mixed, and pure water was added to make the liquid-solid ratio 2:1 (ml:g). The liquid was the total volume of pure water and concentrated sulfuric acid, and the solid was the total mass of calcined material and sodium sulfate. The mixture was subjected to a hydrothermal reaction at 230°C and 2.8 MPa for 1 hour. After filtration, a leachate and a leachate residue were obtained.

[0040] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0041] The impurity removal solution is heated to 90°C, and an equal amount of saturated sodium carbonate solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 1 hour, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 120°C for 3 hours.

[0042] Example 2

[0043] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0044] Take 1 kg of lithium clay ore powder and calcine it at 600℃ for 1 hour to obtain calcined material;

[0045] The calcined material, 500g of 98% concentrated sulfuric acid, and 600g of potassium sulfate were mixed, and pure water was added to make the liquid-solid ratio 6:1 (ml:g). The liquid was the total volume of pure water and concentrated sulfuric acid, and the solid was the total mass of calcined material and potassium sulfate. The mixture was subjected to a hydrothermal reaction at 100°C and 0.1 MPa for 3 hours, and the leachate was obtained after filtration.

[0046] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0047] The impurity removal solution is heated to 100°C, and 3 times the amount of saturated sodium carbonate solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 9 hours, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 60°C for 12 hours.

[0048] Example 3

[0049] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0050] Take 1 kg of lithium clay ore powder and calcine it at 1000℃ for 3 hours to obtain calcined material;

[0051] The aging material, 300g of 98% concentrated sulfuric acid, and 300g of sodium sulfate were mixed, and pure water was added to make the liquid-solid ratio 3:1 (ml:g). The liquid was the total volume of pure water and concentrated sulfuric acid, and the solid was the total mass of aging material and sodium sulfate. The hydrothermal reaction was carried out at a temperature of 140℃ and a pressure of 0.36MPa for 12 hours. After filtration, the leachate was obtained.

[0052] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0053] The impurity removal solution is heated to 95°C, and a saturated sodium carbonate solution of twice the amount of the impurity removal solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 9 hours, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 80°C for 9 hours.

[0054] Example 4

[0055] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0056] 1 kg of lithium clay ore powder was calcined at 700℃ for 6 hours to obtain calcined material;

[0057] The calcined material, 400g of 98% concentrated sulfuric acid, and 200g of potassium sulfate were mixed, and pure water was added to make the liquid-solid ratio 4:1 (ml:g). The liquid was the total volume of pure water and concentrated sulfuric acid, and the solid was the total mass of calcined material and potassium sulfate. The mixture was subjected to a hydrothermal reaction at 180℃ and 1.0 MPa for 2 hours, and the leachate was obtained after filtration.

[0058] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0059] The impurity removal solution is heated to 100°C, and 1.5 times the amount of saturated sodium carbonate solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 6 hours, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 90°C for 6 hours.

[0060] Example 5

[0061] This disclosure discloses a short-process lithium extraction method from lithium clay ore, comprising the following steps:

[0062] 1 kg of lithium clay ore powder was calcined at 800℃ for 9 hours to obtain calcined material;

[0063] The calcined material, 200g of 98% concentrated sulfuric acid, and 400g of potassium sulfate were mixed, and pure water was added to make the liquid-solid ratio 5:1 (ml:g). The liquid was the total volume of pure water and concentrated sulfuric acid, and the solid was the total mass of calcined material and potassium sulfate. The mixture was subjected to a hydrothermal reaction at 200℃ and 1.55MPa for 9 hours, and the leachate was obtained after filtration.

[0064] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0065] The impurity removal solution is heated to 97°C, and 1.2 times the amount of saturated sodium carbonate solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 2 hours, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 100°C for 1 hour.

[0066] Comparative Example 1

[0067] The difference from Example 1 is that sodium sulfate is not added, but the other steps are the same.

[0068] Comparative Example 2

[0069] Take 1 kg of lithium clay ore powder and calcine it at 500℃ for 12 hours to obtain calcined material;

[0070] The aging material, 100g of 98% concentrated sulfuric acid and 100g of sodium sulfate are mixed, and pure water is added to make the liquid-solid ratio 2:1 (ml:g). The liquid is the total volume of pure water and concentrated sulfuric acid, and the solid is the total mass of aging material and sodium sulfate. After filtration, leachate and leachate residue are obtained.

[0071] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0072] The impurity removal solution is heated to 90°C, and an equal amount of saturated sodium carbonate solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 1 hour, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 120°C for 3 hours.

[0073] Comparative Example 3

[0074] Take 1 kg of lithium clay ore powder, 100 g of 98% concentrated sulfuric acid and 100 g of sodium sulfate, mix them, add pure water to make the liquid-solid ratio 2:1 (ml:g), where the liquid is the total volume of pure water and concentrated sulfuric acid, and the solid is the total mass of lithium clay ore powder and sodium sulfate. Carry out a hydrothermal reaction at a temperature of 230℃ and a pressure of 2.8 MPa for 1 hour, and obtain leachate and leachate residue after filtration.

[0075] The leachate was adsorbed and purified using a calcium and magnesium removal resin column to obtain a purified solution.

[0076] The impurity removal solution is heated to 90°C, and an equal amount of saturated sodium carbonate solution is added, wherein the impurity removal solution is based on the molar amount of Li, and the saturated sodium carbonate solution is based on the molar amount of Na; after reacting for 1 hour, the mixture is filtered while hot to obtain lithium carbonate filter residue, which is then dried at 120°C for 3 hours.

[0077] Table 1. Main elemental contents of the lithium clay ore described in Example 1

[0078] Main elements Li Al Mg Ca Si Content (wt.%) 0.29 12.14 0.28 3.77 18.08

[0079] Table 2 Comparison of leachates from each embodiment and the comparative example.

[0080]

[0081] Comparison of experimental parameters

[0082] Table 1 shows the main element content of the lithium clay ore described in Example 1. The Li content is only 0.29 wt.%, which is a low-grade lithium ore, and the aluminum content is relatively high.

[0083] Table 2 compares the leachates of each embodiment with those of the comparative example. It can be seen that the lithium leaching rate in the leachates of the embodiments is greater than 94%, and the low Al / Li ratio indicates that the aluminum content is low, which corresponds to the low aluminum concentration. In addition, the lithium recovery rate in the embodiments is much higher than that in the comparative example.

[0084] Table 2 combined Figure 1 Compared with Comparative Example 1, Example 1 added alkali metal sulfate, which generated alunite, causing a large amount of aluminum to precipitate, resulting in a very low Al / Li ratio in the leachate. In the XRD pattern, it can be seen that the leaching residue of Example 1 contains alunite, while the leaching residue of Comparative Example 1 does not contain alunite.

[0085] Compared to Comparative Example 2, Example 1 underwent a hydrothermal reaction under high pressure, forming alunite, which caused a large amount of aluminum to precipitate, resulting in an extremely low Al / Li ratio in the leachate.

[0086] Compared with Comparative Example 3, Example 1 showed a higher overall lithium recovery rate. This is because the lithium clay ore underwent a dehydroxylation phase transition during high-temperature calcination, which destroyed the complex bonds between lithium and the ore. After heat treatment, lithium existed in the form of Li2O, which is beneficial for subsequent leaching and recovery.

Claims

1. A short process for extracting lithium from lithium clay ore, comprising the following steps: calcining lithium clay ore to obtain a cooked material; subjecting the cooked material to hydrothermal reaction with concentrated sulfuric acid and an alkali metal sulfate dissolved in pure water, and obtaining a leaching solution after filtration; removing impurities from the leaching solution by adsorption with a calcium and magnesium removal resin column, and obtaining a purified solution; adding saturated sodium carbonate solution to the purified solution, and obtaining lithium carbonate residue after filtration; the alkali metal sulfate is at least one of potassium sulfate and sodium sulfate; the temperature of the hydrothermal reaction is 100-230℃, and the pressure is the saturated steam pressure of water at the reaction temperature, i.e. 0.1-2.8 MPa.

2. A process for the extraction of lithium from lithium clay ore according to claim 1, characterized in that, The calcination temperature of the lithium clay ore is 500-1000℃.

3. A process for the extraction of lithium from lithium clay ore according to claim 2, characterized in that, The calcination time of the lithium clay ore is 1-12 h.

4. A process for the extraction of lithium from lithium clay ore as claimed in claim 1 wherein, The mass ratio of the cooked material to the concentrated sulfuric acid is 1:0.1-1.

5. A process for extraction of lithium from lithium clay ore as claimed in claim 1 wherein, The mass ratio of the cooked material to the alkali metal sulfate is 1:0.1-2.

5.

6. A process for the extraction of lithium from lithium clay ore as claimed in claim 1 wherein, The mass concentration of the concentrated sulfuric acid is 98%.

7. A process for the extraction of lithium from lithium clay ore according to claim 6, characterised in that, The liquid-solid ratio of the hydrothermal reaction is 2-6:1 (ml:g), wherein the liquid is the total volume of the concentrated sulfuric acid and the pure water, and the solid is the total mass of the cooked material and the alkali metal sulfate.

8. A process for extraction of lithium from lithium clay ore in short form as claimed in claim 1, wherein, The hydrothermal reaction time is 1-12 h.

9. A process for extraction of lithium from lithium clay ore in short form as claimed in claim 1, wherein, The amount of saturated sodium carbonate solution added is 1-3 times the amount of the purified solution, wherein the purified solution is calculated based on the molar amount of lithium, and the saturated sodium carbonate solution is calculated based on the molar amount of sodium.

10. The process for extraction of lithium from lithium clay ore in short form as claimed in claim 1, further comprising the steps of: The purified solution is heated to 90-100℃, and then the saturated sodium carbonate solution at the same temperature as the purified solution is added.

11. A process for the short course extraction of lithium from lithium clay ore as claimed in claim 10, further comprising the steps of: After adding the saturated sodium carbonate solution to the purified solution, the reaction is carried out for 0.1-3 h.

12. A process for the extraction of lithium from lithium clay ore according to claim 11, wherein, After adding the saturated sodium carbonate solution to the purified solution, the reaction is carried out, and then the solution is filtered while hot.

13. The process for extraction of lithium from lithium clay ore in short form as claimed in claim 1, further comprising the steps of: The lithium carbonate residue is dried.

14. A process for the extraction of lithium from lithium clay ore according to claim 13, wherein, The drying temperature is 60-120℃, and the drying time is 3-12 h.

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