Method for extracting lithium from spodurite and preparing lithium hydroxide

Abstract

The invention provides a method for extracting lithium from spodurite and preparing lithium hydroxide, and belongs to the technical field of resource recycling. The method comprises the following steps: putting phosphorus aluminum lithium stone powder into a plasma arc melting furnace for melting, introducing a reducing Ar-H2 mixed gas for reaction, and cooling to obtain a reaction product; and grinding the obtained reaction product, and soaking in water to obtain a lithium hydroxide solution. According to the method, the high temperature generated by ionization of the mixed gas of reducing Ar-H2 in the plasma arc melting furnace is used for roasting the phosphorus-aluminum-lithium stone, meanwhile, the ionized reducing gas reacts with the phosphorus-aluminum-lithium stone to generate a lithium elementary substance, and the amount of generated residues is small; and cooling the reaction product, grinding, and carrying out water immersion to obtain the lithium hydroxide solution. In the process, an impurity removal step does not need to be added, and the whole technological process has the advantages of being low in energy consumption, simple in process, environmentally friendly and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of resource recycling, and particularly to a method for extracting lithium from spodumene and preparing lithium hydroxide. Background Art

[0002] Lithium has been listed as a "critical mineral" or "strategic mineral" by many countries and plays a crucial role in promoting economic development and ensuring national defense security. It has a wide range of application fields, covering multiple industries such as batteries, glass ceramics, greases, air treatment, medicine, and nuclear industry and aerospace. [1] . Therefore, the booming development of the new energy industry is irresistible, and the demand for lithium is rising rapidly. Currently, lithium is mainly extracted from brines and lithium-containing ores. Brines have the largest reserves, accounting for about 60% of the global lithium reserves, but their development process is restricted by various factors, involving challenges in resource quality, mining environment, and extraction technology. Therefore, lithium-containing ores have become the main source of lithium supply. Spodumene and lepidolite, as the main types of lithium ores, have become key resources for lithium extraction due to their rich reserves. However, with the continuous increase in lithium demand and the continuous rise in prices, the phenomenon of supply shortage is becoming increasingly apparent. Spodumene, as a new type of lithium ore, has the highest lithium content in natural lithium ores, and the Li2O content is usually between 6% and 10%, showing extremely promising lithium extraction potential.

[0003] Currently, the main lithium extraction methods for spodumene are sulfuric acid roasting method, inorganic salt roasting method, and alkali dissolution method. Huang Guangzhu et al. [2] studied the process of preparing lithium carbonate by mixing spodumene with sulfuric acid and roasting at high temperature; Deng Hongyun et al. [3] studied the process of extracting lithium from spodumene by the sulfuric acid method; Dezhi Hu [4] et al. proposed a process combining sulfuric acid roasting and water leaching to achieve efficient comprehensive treatment of spodumene and efficient extraction of Li, Al, and P. The invention patent with the publication number CN110372016A discloses a process for synthesizing battery-grade lithium carbonate from lithium spodumene by the acidification method; the invention patent with the publication number CN116730369A discloses a method for comprehensive utilization of spodumene ore, using sulfation roasting for lithium extraction; the invention patent with the publication number CN116835548A discloses a method for wet comprehensive utilization of extracting phosphorus and lithium salts from spodumene, using two-stage countercurrent leaching of high-temperature low-acid and high-temperature high-acid to leach lithium, phosphorus, and aluminum from spodumene; the invention patent with the publication number CN117003264A discloses a method for preparing lithium carbonate using spodumene, roasting spodumene with concentrated sulfuric acid for lithium extraction and preparing lithium carbonate; the invention patents with the publication numbers CN107162024A and CN107188205A disclose a process for extracting lithium carbonate from lithium spodumene by the acidification method. Alafara A et al. [5]The research detected a Nigerian spodumene ore containing 12.47% Li2O, and used the mixed roasting of sodium sulfate and spodumene ore to extract lithium; Qingfeng Zhou et al. [6] Adopted the calcium sulfate roasting - water leaching process to extract lithium from spodumene; Dezhi Hu et al. [7] Adopted the mixed roasting process of CaSO4 and CaO to selectively recover Li, P, and Al in spodumene. The invention patent with the publication number CN107188204A disclosed a process for extracting lithium hydroxide from spodumene by the lime method, using the mixed roasting of sodium sulfate and calcium hydroxide to leach lithium. The invention patents with the publication numbers CN109019643B, CN113830746A, CN113981244A, CN116497236A, CN117070772A, etc. used single inorganic salts or mixed inorganic salts and spodumene for high - temperature roasting to extract lithium. The invention patents with the publication numbers CN111137868A and CN111204726B disclosed a method for preparing lithium phosphate from spodumene, using the low - temperature alkali leaching method to extract lithium in spodumene and prepare lithium phosphate. The invention patent with the publication number CN111252749A disclosed a method for preparing iron phosphate and aluminum hydroxide from spodumene, dissolving spodumene by alkali leaching to extract lithium and aluminum elements in spodumene. The invention patent with the publication number CN118026220A disclosed a method for preparing lithium hydroxide from lithium ore, using lithium ore as raw material to carry out hydrothermal reaction with mixed alkali slurry and crystal regulator to extract lithium.

[0004] The sulfuric acid method for extracting lithium from spodumene has strong corrosiveness to equipment, requires high equipment material requirements, increases production costs, and at the same time, the roasted materials are thin and sticky to the wall, making them difficult to handle; the inorganic salt method roasting requires adding a large amount of inorganic salts for roasting, generates a large amount of residues, and the caking phenomenon after roasting is relatively serious, making crushing difficult; at the same time, a large amount of other impurities will be introduced, and the impurity removal process is complex; although the alkali dissolution method generates less residue, more impurity elements are dissolved in the solution, and the impurity removal process is complex.

[0005] The sources of the literature cited in the above background technology are as follows:

[0006] [1] Zhao Q, Ma B, Zhou H, et al. Clean and efficient extraction of lithium from montebrasite ore by aluminum sulfate roasting method: Thermal behavior and process optimization[J]. Journal of Environmental Chemical Engineering, 2024, 12(5): 113632-113632.

[0007] [2] Huang GZ, Wang J, Zhao Q. Process study on preparation of lithium carbonate from montebrasite[J]. Phosphate & Compound Fertilizer, 2019, 34(11): 7-9.

[0008] [3] Deng HY, Zhong SW, Liu YX, et al. Process study and optimization on extraction of lithium from montebrasite by sulfuric acid method[J]. Nonferrous Metals Science and Engineering, 2022, 13(4): 35-43.

[0009] [4] Dezhi H, Baozhong M, Yubo L, et al. Phase transformation of montebrasite for efficient extraction and separation of lithium, aluminum, phosphorus[J]. Journal of Environmental Chemical Engineering, 2023, 11(3).

[0010] [5] Baba AA, Olaoluwa DT, Balogun AF, et al. High-grade Li2SO4 from a local montebrasite ore as industrial raw material for managing bipolar disorder[J]. Springer, 2023, 152: 1138-1143.

[0011] [6] Zhou Q, Ma X, Xiong

[0012] [7]Hu D,Ma B,Lv Y,et al.A sustainable process for efficient extraction of lithium,aluminum,and phosphorus from montebrasite[J].ACSSustainable Chemistry&Engineering,2024,12(9):3390-3898. Summary of the invention

[0013] In view of this, in order to solve the above-mentioned deficiencies of the lithium aluminum phosphate sulfuric acid method, inorganic salt method and alkali dissolution method in the prior art, the present invention provides a method for extracting lithium from aluminum phosphate and preparing lithium hydroxide, using the high temperature generated by the ionization of the reducing Ar-H2 mixed gas in a plasma arc melting furnace to roast the aluminum phosphate, and at the same time, the ionized reducing gas reacts with the aluminum phosphate to produce lithium single substance, and the amount of residue produced is small; the product after the reaction is cooled, ground and then soaked in water to obtain a lithium hydroxide solution. After evaporation concentration and cooling crystallization, lithium hydroxide crystals with higher purity are obtained. No impurity removal step is required in this process, and the entire process has the characteristics of low energy consumption, simple process, and environmental friendliness.

[0014] To achieve the above object, the present invention provides the following technical solutions:

[0015] A method for extracting lithium from pyroxenite and preparing lithium hydroxide comprises the following steps:

[0016] Step (1), placing the phosphate aluminum lithium stone powder into a plasma arc furnace for melting, introducing a reducing Ar-H2 mixed gas for reaction, and cooling to obtain a reaction product;

[0017] Step (2), grinding the reaction product of step (1) and then soaking it in water to obtain a lithium hydroxide solution.

[0018] Preferably, in step (1), the volume ratio of Ar to H2 is 1:(0.1-1).

[0019] Preferably, in step (1), the melting temperature is 700-950°C.

[0020] Preferably, it further includes:

[0021] Step (3): Filter, evaporate and concentrate, cool and crystallize, and dry the lithium hydroxide solution obtained in step (2) in sequence to obtain a lithium hydroxide product.

[0022] Preferably, in step (3), the conditions for evaporation and concentration are to stop heating when the lithium hydroxide is evaporated to 1 / 4 - 1 / 6 of the original solution volume at 100 - 150 °C.

[0023] Preferably, in step (3), the temperature for cooling and crystallization is 20 - 50 °C, and the crystallization time is 1 - 5 h.

[0024] Preferably, in step (3), the drying temperature is 100 - 150 °C, and the drying time is 0.5 - 3 h.

[0025] Preferably, in step (2), the conditions for water immersion are:

[0026] The water immersion temperature is 30 - 90 °C, the liquid - solid ratio of the water immersion solution is 2:1 - 8:1, the water immersion time is 1 - 4 h, and the stirring speed is 100 - 400 rpm.

[0027] Preferably, in step (1), the reaction time is 1 - 10 min.

[0028] Preferably, in step (1), the product at the bottom of the plasma arc furnace is rapidly cooled with cooling water.

[0029] The present invention has the following beneficial effects compared with the prior art:

[0030] The present invention relates to an innovative method for extracting lithium from spodumene and preparing lithium hydroxide. This method uses a reducing Ar - H2 mixed gas to be ionized in a plasma arc melting furnace to generate a high - temperature environment for roasting spodumene. During this process, the reducing gas generated by ionization reacts chemically with spodumene, effectively converting the lithium element in spodumene into lithium metal. A significant advantage of this method is that the amount of residue generated is relatively small, which helps with subsequent processing and resource recovery. The reaction product after roasting treatment, through cooling and grinding steps, and then water immersion treatment, can obtain a solution containing lithium hydroxide. Subsequently, through evaporation and concentration and cooling and crystallization steps, a lithium hydroxide crystal product with high purity can be obtained. It should be noted that during the entire preparation process, there is no need to additionally add impurity - removal steps, which not only simplifies the process flow but also reduces energy consumption. In addition, this method also has the advantages of simple process flow and environmental friendliness, providing an efficient and environmentally friendly solution for the extraction of lithium resources and the preparation of lithium hydroxide. Specific embodiments

[0031] The present invention relates to an innovative method for extracting lithium from spodumene and preparing lithium hydroxide, and the specific steps are as follows:

[0032] Step (1): Place spodumene powder (preferably 100-200 mesh) in a plasma arc furnace for melting treatment. During this process, introduce a reducing mixed gas Ar-H2 in a certain proportion to promote the reaction. The volume ratio of Ar to H2 is set within the range of 1:(0.1-1) to ensure that the reaction proceeds in a suitable reducing environment. The reaction time is controlled within 1-10 minutes to ensure the sufficiency of the reaction. The melting temperature is maintained between 700-950 °C to achieve the best effect of spodumene melting. After the reaction is completed, the product at the bottom of the plasma arc furnace is rapidly cooled by cooling water to prevent unnecessary chemical changes of the product at high temperature.

[0033] Step (2): Grind the reaction product obtained in step (1) (preferably to 140 mesh), and then perform a water leaching operation to obtain a lithium hydroxide solution. The conditions during the water leaching process include: the water leaching temperature is set within the range of 30-90 °C to ensure the efficiency of the water leaching process; the ratio of the water leaching solution to the solid is controlled between 2:1-8:1 to ensure a sufficient leaching effect; the water leaching time is maintained within 1-4 hours to ensure the sufficient dissolution of lithium ions; at the same time, the stirring speed is set at 100-400 rpm to promote mass transfer during the water leaching process.

[0034] To obtain a lithium hydroxide solid product, the present invention further includes step (3):

[0035] Filter, evaporate and concentrate, cool and crystallize, and dry the lithium hydroxide solution obtained in step (2) in sequence to finally obtain a lithium hydroxide product. In the evaporation and concentration stage, the lithium hydroxide solution is evaporated at a temperature of 100-120 °C until the volume of the original solution is reduced to 1 / 4-1 / 6, and then the heating is stopped to obtain a concentrated lithium hydroxide solution. Subsequently, in the cooling and crystallization stage, the concentrated solution is crystallized at a temperature of 20-50 °C, and the crystallization time is controlled within 1-5 hours to form lithium hydroxide crystals. Finally, in the drying stage, the crystals are dried at a temperature of 100-150 °C, and the drying time is maintained within 0.5-3 hours to remove excess moisture and obtain the final lithium hydroxide solid product.

[0036] The technical solution of the present invention will be clearly and detailedly described below in conjunction with specific embodiments.

[0037] The main components of the raw materials used in the following embodiments of the present invention are shown in Table 1:

[0038] Table 1 Main components of spodumene

[0039] Component <![CDATA[Li2O]]> <![CDATA[P2O5]]> <![CDATA[Al2O3]]> <![CDATA[SiO2]]> Others Content / wt% 6.92 45.21 29.31 15.53 3.03

[0040] Example 1

[0041] A method for extracting lithium from spodumene and preparing lithium hydroxide, specifically including the following steps:

[0042] Step (1): Place 10 g of spodumene powder ground to 200 mesh in a plasma arc furnace and melt it at 950 °C. Introduce a reducing Ar-H2 mixed gas with a volume ratio of argon to hydrogen of 1:1 and react for 10 min; cool to obtain a reaction product.

[0043] Step (2): Grind the reaction product to 140 mesh and then mix it with water at 90 °C, with a liquid-solid ratio of water leaching of 8:1 and a water leaching time of 4 h, and a stirring speed of 400 rpm to obtain a lithium hydroxide solution.

[0044] Step (3): Filter the lithium hydroxide solution obtained in step (2) to remove the filter residue; stop heating when the lithium hydroxide solution is evaporated and concentrated to 1 / 4 of the original volume at 150 °C, then cool and crystallize at 20 °C for 5 h and dry at 150 °C for 3 h to obtain a lithium hydroxide product.

[0045] In this example, the lithium recovery rate is 97.6%, the lithium hydroxide yield is 93.21%, and the purity is 99.53%.

[0046] Example 2

[0047] Same as Example 1, except that the melting temperature is 850 °C.

[0048] In this example, the lithium recovery rate is 98.1%, the lithium hydroxide yield is 93.11%, and the purity is 99.06%.

[0049] Example 3

[0050] Same as Example 1, except that the melting temperature is 700 °C.

[0051] In this example, the lithium recovery rate is 96.13%, the lithium hydroxide yield is 93.64%, and the purity is 99.13%.

[0052] Example 4

[0053] Same as Example 2, except that the volume ratio of argon to hydrogen is 1:0.5.

[0054] In this example, the lithium recovery rate is 95.17%, the lithium hydroxide yield is 91.39%, and the purity is 99.61%.

[0055] Example 5

[0056] Same as Example 2, except that the volume ratio of argon to hydrogen is 1:0.1.

[0057] In this example, the lithium recovery rate is 95.31%, the lithium hydroxide yield is 91.43%, and the purity is 99.03%.

[0058] Example 6

[0059] Same as Example 5, except that the reaction time of step (1) is 5 min.

[0060] In this example, the lithium recovery rate is 95.88%, the lithium hydroxide yield is 92.61%, and the purity is 99.61%.

[0061] Example 7

[0062] Same as Example 5, except that the reaction time of step (1) is 1 min.

[0063] In this example, the lithium recovery rate is 95.31%, the lithium hydroxide yield is 91.51%, and the purity is 99.09%.

[0064] Example 8

[0065] Same as Example 7, except that the liquid-solid ratio of the water leaching in step (2) is 6:1.

[0066] In this example, the lithium recovery rate is 95.09%, the lithium hydroxide yield is 90.16%, and the purity is 99.61%.

[0067] Example 9

[0068] Same as Example 7, except that the liquid-solid ratio of the water leaching in step (2) is 2:1.

[0069] In this example, the lithium recovery rate is 94.97%, the lithium hydroxide yield is 91.67%, and the purity is 99.53%.

[0070] Example 10

[0071] Same as Example 1, except that in step (3), the lithium hydroxide solution obtained in step (2) is filtered to remove the filter residue; the lithium hydroxide solution is evaporated and concentrated to 1 / 6 of the original volume at 100 °C and then the heating is stopped, and then cooled and crystallized at 30 °C for 3 h and dried at 120 °C for 0.5 h to obtain the lithium hydroxide product.

[0072] In this example, the lithium recovery rate is 96.89%, the lithium hydroxide yield is 92.91%, and the purity is 99.34%.

[0073] Example 11

[0074] Same as Example 1, except that in step (3), the lithium hydroxide solution obtained in step (2) is filtered to remove the filter residue; the lithium hydroxide solution is evaporated and concentrated at 130 °C until it reaches 1 / 5 of the original volume, then heating is stopped, and then it is cooled and crystallized at 50 °C for 1 h and dried at 100 °C for 2 h to obtain the lithium hydroxide product.

[0075] In this example, the lithium recovery rate is 97.30%, the lithium hydroxide yield is 93.61%, and the purity is 99.66%.

[0076] Comparative Example 1

[0077] In this comparative example, the reducing gas (Ar-H2 mixed gas) in Example 6 is replaced with Ar gas, and other conditions remain unchanged.

[0078] In this example, the lithium recovery rate is 55.13%, the lithium hydroxide yield is 93.83%, and the purity is 99.61%.

[0079] Comparative Example 2

[0080] In this comparative example, the reducing gas (Ar-H2 mixed gas) in Example 6 is replaced with an (Ar-CO mixed gas) with a ratio of 1:0.1, and other conditions remain unchanged.

[0081] In this example, the lithium recovery rate is 60.11%, the lithium hydroxide yield is 88.11%, and the purity is 95.71%.

[0082] Comparative Example 3

[0083] In this comparative example, the reducing gas (Ar-H2 mixed gas) in Example 6 is replaced with a composite reducing agent (high-silicon ferrosilicon, aluminum powder, aluminum-silicon powder) with a ratio of 1:0.5:0.5, and other conditions remain unchanged.

[0084] In this example, the lithium recovery rate is 51.11%, the lithium hydroxide yield is 71.31%, and the purity is 83.65%.

[0085] The above are only the preferred embodiments and comparative examples of the present invention, and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for extracting lithium from spodumene and preparing lithium hydroxide, characterized in that, It includes the following steps: Step (1): Put spodumene powder into a plasma arc furnace for melting, introduce a mixed gas of reducing Ar-H2 for reaction, and cool to obtain a reaction product; Step (2): Grind the reaction product of step (1) and then leach it with water to obtain a lithium hydroxide solution.

2. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 1, characterized in that, In step (1), the volume ratio of Ar to H2 is 1:(0.1 - 1).

3. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 1, characterized in that, In step (1), the melting temperature is 700 - 950 °C.

4. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 1, characterized in that, It also includes: Step (3): Filter, evaporate and concentrate, cool and crystallize, and dry the lithium hydroxide solution obtained in step (2) in sequence to obtain a lithium hydroxide product.

5. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 4, characterized in that, In step (3), the conditions for evaporation and concentration are to stop heating when lithium hydroxide is evaporated to 1 / 4 - 1 / 6 of the original solution volume at 100 - 150 °C.

6. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 4, characterized in that, In step (3), the temperature for cooling and crystallization is 20 - 50 °C, and the crystallization time is 1 - 5 h.

7. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 4, characterized in that, In step (3), the drying temperature is 100 - 150 °C, and the drying time is 0.5 - 3 h.

8. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 1, characterized in that, In step (2), the conditions for water leaching are: The water leaching temperature is 30 - 90 °C, the liquid-solid ratio of the water leaching solution is 2:1 - 8:1, the water leaching time is 1 - 4 h, and the stirring speed is 100 - 400 rpm.

9. A method for extracting lithium from spodumene and preparing lithium hydroxide according to claim 1, characterized in that, In step (1), the reaction time is 1 - 10 min.

10. A method for extracting lithium from spodumene and preparing lithium hydroxide according to any one of claims 1-9, characterized in that, In step (1), the product at the bottom of the plasma arc furnace is quickly cooled with cooling water.