A method for preparing lithium carbonate from lithium ore

Abstract

The present application relates to the technical field of separation and purification of inorganic materials, and specifically discloses a method for preparing lithium carbonate from lithium ore. The preparation method comprises: pre-treating the lithium ore, adding water, stirring and leaching, and filtering to obtain a leachate; adding a complexing agent to the leachate, mixing, filtering, collecting a filter cake, adding deionized water and a complexing agent to the filter cake, and simultaneously introducing carbon dioxide to obtain a solution containing lithium bicarbonate; mixing with a cationic chelating resin, reacting, filtering, and collecting a filtrate to obtain a first mixed solution; mixing the first mixed solution with an anion exchange resin, reacting, filtering, and collecting a filtrate to obtain a second mixed solution; adding sodium carbonate to the second mixed solution, mixing, filtering, and obtaining a crude lithium carbonate product; repeatedly washing with water, filtering, and drying to obtain lithium carbonate. The method for preparing lithium carbonate from lithium ore of the present application has the advantages of reducing impurities and improving the purity of lithium carbonate through the synergistic effect between the steps.

Description

Technical Field

[0001] The present application relates to the technical field of separation and purification of inorganic materials, and in particular to a method for preparing lithium carbonate from lithium ore. Background Art

[0002] Lithium, the first element in Group IA, possesses the highest redox potential, the largest specific heat capacity, and the smallest density. Therefore, lithium plays a vital role in electronics, metallurgy, chemicals, medicine, nuclear energy, aerospace, and energy, earning it the title "the key energy element driving global progress." Over 150 lithium-containing minerals have been discovered in nature, primarily in the forms of lepidolite, spodumene, and petalite. In addition to lithium-bearing ores, lithium is also widely found in salt lake brines. The world's lithium resources are primarily distributed in South and North America and Asia. my country possesses abundant lithium reserves, with total proven reserves ranking second in the world, behind only Bolivia.

[0003] Lithium exists in various compounds in nature. Among them, lithium carbonate, as the most important basic lithium salt, is the basic raw material for the preparation of other lithium compounds such as metallic lithium, lithium chloride, lithium molybdate, and butyl lithium. It can also be used to prepare lithium-ion batteries and electrolytic bath additives for aluminum smelting. It is also widely used in industries such as glass, ceramics, medicine, and food.

[0004] Currently, there are two methods for producing lithium carbonate: extracting lithium from lithium ore and extracting lithium from salt lake brine. Methods for extracting lithium carbonate from lithium ore include lime sintering, sulfate method, chloride roasting, and alkaline autoclave. Methods for purifying lithium carbide include carbonization, electrolysis, causticization, ion exchange, and recrystallization. However, the lithium carbonate produced using these methods contains high impurity levels, resulting in low purity. Summary of the Invention

[0005] In order to reduce the impurity content in lithium carbonate and improve the purity of lithium carbonate, the present application provides a method for preparing lithium carbonate from lithium ore.

[0006] In a first aspect, the present application provides a method for preparing lithium carbonate from lithium ore, using the following technical solution:

[0007] A method for preparing lithium carbonate from lithium ore comprises the following steps:

[0008] S1: pre-treating the lithium ore, adding deionized water, stirring and leaching, and filtering to obtain a leachate;

[0009] S2: adding a complexing agent to the leachate, mixing uniformly, filtering, collecting the filter cake, and adding deionized water to the filter cake while introducing carbon dioxide to obtain a solution containing lithium bicarbonate;

[0010] S3: mixing the solution containing lithium bicarbonate with a cationic chelating resin, reacting, filtering, and collecting the filtrate to obtain a first mixed solution;

[0011] S4: mixing the first mixed solution with the modified chitosan-based chelating resin, reacting, filtering, and collecting the filtrate to obtain a second mixed solution;

[0012] S5: adding sodium carbonate to the second mixed solution, mixing evenly, and filtering to obtain crude lithium carbonate;

[0013] S6: The crude lithium carbonate is repeatedly washed with deionized water, filtered, and dried to obtain lithium carbonate.

[0014] Furthermore, a method for preparing lithium carbonate from lithium ore comprises the following steps:

[0015] S1: pre-treating the lithium ore, adding deionized water, stirring and leaching, and filtering to obtain a leachate;

[0016] S2: adding a complexing agent to the leachate, mixing uniformly, filtering, collecting the filter cake, and adding deionized water to the filter cake while introducing carbon dioxide to obtain a solution containing lithium bicarbonate;

[0017] S3: mixing the solution containing lithium bicarbonate with a cationic chelating resin, reacting for 1-2 hours, filtering, and collecting the filtrate to obtain a first mixed solution;

[0018] S4: mixing the first mixed solution with a modified chitosan-based chelating resin, reacting for 1-2 hours, filtering, and collecting the filtrate to obtain a second mixed solution;

[0019] S5: adding sodium carbonate to the second mixed solution, mixing evenly, and filtering to obtain crude lithium carbonate;

[0020] S6: repeatedly washing the crude lithium carbonate with deionized water, filtering, and drying to obtain lithium carbonate;

[0021] In step S1, the weight ratio of lithium ore to deionized water is 1:(1-2); in step S2, the weight ratio of lithium ore to complexing agent is 1:(0.6-0.9); in step S3, the weight ratio of lithium ore to deionized water is 1:(10-20); the flow rate of introduced carbon dioxide is 40-80 L / h, and the introduction time is 40-60 min; in step S3, the weight ratio of lithium ore to cationic chelating resin is 1:(1-2); in step S4, the weight ratio of lithium ore to modified chitosan-based chelating resin is 1:(1-2); and the weight ratio of lithium ore to sodium carbonate is 1:(2-3).

[0022] By adopting the above technical solution, the method for preparing lithium carbonate from lithium ore of the present application, through the synergistic effect between each step, not only reduces the content of calcium ions, magnesium ions, aluminum ions, and boron, but also improves the purity of lithium carbonate, wherein the lithium carbonate content is 99.17-99.98%, the calcium ion content is 0.022-0.123%, the magnesium ion content is 0.015-0.068%, the boron content is 0.014-0.073%, and the aluminum ion content is 0.017-0.11%.

[0023] First, the lithium ore is pretreated. Most natural lithium ores are α-lithium ore, which has fine monoclinic crystals and is chemically inert, virtually unreactive with acids and bases. To effectively extract lithium carbonate from lithium ore, the ore must be pretreated to convert it into β-lithium ore, increasing its chemical activity and allowing it to react with various acids and bases, facilitating the extraction of lithium carbonate. After pretreatment, the lithium ore is added with deionized water and filtered to prepare a leachate, which removes dissolved potassium and sodium ions. A chelating agent is then added, filtered, and passed through a stream of carbon dioxide to produce a solution containing lithium bicarbonate. The chelating agent complexes with the calcium, magnesium, and aluminum ions in the lithium ore, forming a precipitate, thereby removing some of the calcium, magnesium, and aluminum ions.

[0024] The solution containing lithium bicarbonate is then mixed with a cationic chelating resin, reacted, and filtered. After obtaining the first mixed solution, the solution is mixed with a modified chitosan-based chelating resin, reacted, and filtered to obtain the second mixed solution. Finally, sodium carbonate is added, filtered, and a crude product is obtained. After purification, lithium carbonate is obtained. Cationic chelating resin can first form a coordinated covalent bond with the high-valent metal ion to form a chelate with stable structure, and then removed after filtration. When the solution containing lithium bicarbonate passes through the cationic chelating resin, it can effectively adsorb high-valent ions. Among the similar ions of the same valence, the ion with the larger diameter is more strongly adsorbed. It can first adsorb ferric ion, aluminum ion, calcium ion, and magnesium ion. The adsorption of lithium ions is not obvious, so some metallic impurities are further removed. The modified chitosan-based chelating resin improves its adsorption function by grafting adsorption functional groups, and after adsorption by the cationic chelating resin, the influence of most magnesium ions and calcium ions is removed, so that the modified chitosan-based chelating resin can better adsorb boron and can further adsorb a small part of magnesium ions and calcium ions, thereby reducing the content of impurities and improving the purity of lithium carbonate.

[0025] Preferably, the specific method of pretreatment in step S1 is: crushing, grinding, and screening the lithium ore to obtain ore powder, and performing crystal conversion and roasting on the ore powder to obtain roasted material; after cooling, grinding again, and acidifying and roasting to obtain acidified clinker.

[0026] Furthermore, the specific method of pretreatment in step S1 is: crushing, grinding, and screening the lithium ore to a particle size of 175-180 μm to obtain ore powder, and performing crystal transformation roasting on the ore powder at a temperature of 1150-1200°C to obtain a roasted material; after cooling, grinding again to a particle size of 70-75 μm, and performing sulfuric acid roasting at a temperature of 200-300°C to obtain an acidified clinker.

[0027] By adopting the above technical solution and utilizing the above pretreatment method to subject the lithium ore to crystal conversion roasting and acidification roasting, the α type can be converted into the β type, and the physical and chemical properties also undergo significant changes with the change of the crystal structure, the chemical activity increases, and it can react with acids and alkalis, thereby facilitating the subsequent preparation of lithium carbonate and facilitating the purification of lithium carbonate.

[0028] Preferably, the complexing agent in step S2 is one or more of nitrilotriacetic acid, diethanolamine, and EDTA.

[0029] More preferably, the complexing agent in step S2 is a mixture of nitrilotriacetic acid, diethanolamine, and EDTA, and the weight ratio of the three is 1:1:1.

[0030] By adopting this technical solution, nitrilotriacetic acid can provide four coordination bonds with metal ions. Its small molecule size allows it to form stable chelates with calcium, magnesium, and aluminum ions due to its strong complexing ability. Diethanolamine also has a certain complexing effect; EDTA can form chelates with divalent metal ions such as magnesium, calcium, and ferrous ions. The synergistic effect of these three agents can effectively remove metallic impurities from lithium ore, thereby improving the purity of lithium carbonate.

[0031] Preferably, in step S2, the solution containing lithium bicarbonate is thermally decomposed after being obtained.

[0032] Preferably, the specific method of the pyrolysis is as follows: heating the solution containing lithium bicarbonate in a water bath with continuous stirring, stopping the heating after a period of time, filtering under reduced pressure, and collecting the filtrate to obtain a pyrolyzed solution containing lithium bicarbonate.

[0033] Furthermore, the specific method of the pyrolysis is as follows: heating the solution containing lithium bicarbonate in a water bath at a temperature of 80-100° C., stirring continuously for 30-40 minutes, stopping heating, filtering under reduced pressure, collecting the filtrate, and obtaining a pyrolyzed solution containing lithium bicarbonate.

[0034] By adopting the above technical solution, some impurities can be converted into insoluble carbonates through pyrolysis and carbonization, and then some impurities can be removed through filtration, thereby improving the purity of lithium carbonate.

[0035] Preferably, the cationic chelating resin in step S3 is an aminophosphonic acid resin.

[0036] By adopting the above technical solution, the aminophosphonic acid resin is a chelating resin with a macroporous structure and a weakly acidic aminophosphonic acid as the active group. This chemical structure helps metal ions form complexes and has a strong affinity for cations, especially for low atomic weight metals such as calcium ions and magnesium ions. Therefore, the use of aminophosphonic acid resin as a cationic chelating resin is beneficial for the removal of calcium ions and magnesium ions, thereby facilitating the improvement of the purity of lithium carbonate.

[0037] Preferably, the aminophosphonic acid resin is treated by the following method before use: the aminophosphonic acid resin is immersed in a sodium chloride solution, taken out, washed, and subjected to acid washing, water washing, alkali washing, water washing, and acid washing to obtain the treated aminophosphonic acid resin.

[0038] Furthermore, the aminophosphonic acid resin is treated by the following method before use: the aminophosphonic acid resin is soaked in a sodium chloride solution for 18-22 hours, taken out, washed with deionized water until the discharged water is no longer yellow, rinsed the soaked aminophosphonic acid resin from top to bottom with a hydrochloric acid solution, and then rinsed with deionized water to a pH value of 6-7, then rinsed with a sodium hydroxide solution from top to bottom, and then rinsed with deionized water to a pH value of 7-8, and finally washed once with a hydrochloric acid solution to obtain a treated aminophosphonic acid resin;

[0039] The mass fraction of the sodium chloride solution is 10%, and the amount of the sodium chloride solution added to 1g of the aminophosphonic acid resin is 1-3mL; the mass fraction of the hydrochloric acid solution is 5%, and the amount of the hydrochloric acid solution added to 1g of the aminophosphonic acid resin is 0.8-1.2mL; the mass fraction of the sodium hydroxide solution is 4%, and the amount of the sodium hydroxide solution added to 1g of the aminophosphonic acid resin is 0.8-1.2mL.

[0040] By adopting the above technical scheme, although the unused aminophosphonic acid resin contains certain moisture, it will also expand after encountering water, and its volume increases rapidly, causing the aminophosphonic acid resin to fragment, affecting its use. The aminophosphonic acid resin is placed in a sodium chloride solution and soaked, which can prevent it from fragmenting when encountering water and reduce the speed of swelling when encountering water. The purpose of pickling is to backwash away mechanical impurities and inorganic impurities with deionized water, and the purpose of alkali washing is to remove organic impurities. Finally, the aminophosphonic acid resin is pickled again and hydrogenated, which can improve the adsorption capacity to impurities, facilitate better removal of impurities, and improve the purity of lithium carbonate.

[0041] Preferably, the modified chitosan-based chelate resin in step S4 is prepared by modifying the chitosan-based chelate resin with 2-amino-1,3-propanediol.

[0042] Preferably, the modified chitosan chelate resin is prepared by the following method:

[0043] A1: Place chitosan powder in acetic acid solution, mix well, add sodium hydroxide solution, mix, let stand, filter, wash, and dry to obtain chitosan microspheres;

[0044] A2: Place chitosan microspheres in deionized water, add isopropyl alcohol, adjust the pH to 9-11, add epichlorohydrin, heat and reflux, filter, wash, and dry to obtain modified chitosan microspheres;

[0045] A3: Place the modified chitosan microspheres in an ethanol solution, add dioxane, a catalyst, and 2-amino-1,3-propanediol, heat to a high temperature, reflux reaction, filter, wash, and dry to obtain a modified chitosan-based chelating resin.

[0046] Furthermore, the modified chitosan-based chelating resin is prepared by the following method:

[0047] A1: Place chitosan powder in acetic acid solution, mix well, add sodium hydroxide solution, mix, let stand for 10-14 hours, filter, wash with deionized water until neutral, and dry to obtain chitosan microspheres;

[0048] A2: Place chitosan microspheres in deionized water, add isopropyl alcohol, adjust the pH to 9-11 with sodium hydroxide solution, add epichlorohydrin, heat to 50-70°C, reflux for 3-5 hours, filter, wash with deionized water and ethanol solution 5-7 times respectively, and dry to obtain modified chitosan microspheres;

[0049] A3: Place the modified chitosan microspheres in an ethanol solution, add dioxane, a catalyst, and 2-amino-1,3-propanediol, heat to 40-60°C, reflux for 6-8 hours, filter, wash with deionized water and methanol solution 5-7 times, respectively, and dry to obtain a modified chitosan-based chelating resin;

[0050] In step A1, the amount of acetic acid solution added to each 1g of chitosan powder is 18-22mL, and the mass fraction of the acetic acid solution is 8%; the amount of sodium hydroxide solution added to each 1g of chitosan powder is 2-3mL, and the mass fraction of the sodium hydroxide solution is 40%; in step A2, the amount of deionized water added to each 1g of chitosan microspheres is 15-17mL, the amount of isopropyl alcohol added to each 1g of deionized water is 22-26mL, and the mass fraction of the sodium hydroxide solution is 40%; the amount of epichlorohydrin added to each 1g of chitosan microspheres is 4.5-5mL; in step A3, the amount of ethanol solution added to each 1g of modified chitosan microspheres is 10-14mL, and the mass fraction of the ethanol solution is 30%; the amount of dioxane added to each 1g of modified chitosan microspheres is 10-14mL; the weight ratio of modified chitosan microspheres to catalyst is 1:(0.4-0.6), and the mass fraction of the methanol solution is 47%.

[0051] By adopting the above technical solution, chitosan powder is first condensed into balls in an alkaline solution, and then the stability and mechanical strength are enhanced through chlorination and cross-linking reactions. Then, 2-amino-1,3-propanediol is grafted onto the surface of the modified chitosan microspheres through an amination reaction to obtain a modified chitosan-based chelating resin, forming a network structure, thereby enhancing the alkali and acid resistance and further enhancing the adsorption performance, and can further improve the adsorption of boron, calcium ions, and magnesium ions, reduce the content of impurities, and improve the purity of lithium carbonate.

[0052] Preferably, the weight ratio of the chitosan powder to 2-amino-1,3-propanediol is 1:(5-6).

[0053] If the amount of 2-amino-1,3-propanediol added is too low, less 2-amino-1,3-propanediol will be grafted onto the chitosan surface, affecting adsorption. If the amount of 2-amino-1,3-propanediol added is too high, when the chitosan surface reaches saturation, it will cause waste of raw materials and increase production costs. By adopting the above technical solution, when the amount of 2-amino-1,3-propanediol added is within the above range, it can be better grafted onto chitosan, improving the adsorption of chitosan, thereby improving the adsorption capacity of impurities and increasing the purity of lithium carbonate.

[0054] In summary, this application includes at least one of the following beneficial technical effects:

[0055] 1. Since the lithium carbonate in the lithium ore is prepared in the present application by the method of lithium ore pretreatment-complex precipitation-cation chelate resin adsorption-modified chitosan-based chelate resin adsorption-crude product preparation-purification, the influence of impurities such as magnesium ions, calcium ions, aluminum ions, and boron in the lithium ore can be removed by the adsorption of the complexing agent, the cationic chelate resin, and the modified chitosan-based chelate resin, thereby improving the purity of the lithium carbonate, and the lithium carbonate content can reach 99.98%, the calcium ion content can be reduced to 0.022%, the magnesium ion content can be reduced to 0.015%, the boron content can be reduced to 0.014%, and the aluminum ion content can be reduced to 0.017%.

[0056] 2. In the present application, aminophosphonic acid resin is preferably selected as the cationic chelating resin, and is treated before use by soaking in sodium chloride solution - pickling - washing with water - alkali washing - washing with water - pickling, which can reduce the fragmentation of the aminophosphonic acid resin when it comes into contact with water, reduce the rate of swelling when it comes into contact with water, and remove mechanical impurities, inorganic impurities and organic impurities on the aminophosphonic acid resin, so as to facilitate better adsorption, facilitate better removal of impurities in lithium ore, and improve the purity of lithium carbonate. DETAILED DESCRIPTION

[0057] The following is a further detailed description of this application in conjunction with the specific content.

[0058] raw material

[0059] The catalyst is triethylamine.

[0060] Preparation Example

[0061] Preparation Example 1

[0062] A modified chitosan-based chelating resin is prepared by the following method:

[0063] A1: Place 2 kg of chitosan powder in 40 L of 8% acetic acid solution, mix thoroughly, add 5 L of 40% sodium hydroxide solution, mix, let stand for 12 hours, filter, wash with deionized water until neutral, and dry to obtain chitosan microspheres;

[0064] A2: Chitosan microspheres were placed in deionized water, isopropyl alcohol was added, the pH was adjusted to 10 with 40% sodium hydroxide solution, epichlorohydrin was added, the temperature was raised to 60°C, refluxed for 4 hours, filtered, washed six times with deionized water and ethanol solution, and dried to obtain modified chitosan microspheres;

[0065] A3: Modified chitosan microspheres were placed in a 30% by mass ethanol solution, and dioxane, a catalyst, and 10 kg of 2-amino-1,3-propanediol were added. The mixture was heated to 50°C and refluxed for 7 hours. The mixture was filtered and washed six times with deionized water and six times with a 47% by mass methanol solution, respectively. The mixture was then dried to obtain a modified chitosan-based chelating resin.

[0066] Among them, the amount of deionized water added to each 1g of chitosan microspheres in step A2 is 16mL, the amount of isopropanol added to each 1g of chitosan microspheres is 24mL, and the amount of epichlorohydrin added to each 1g of chitosan microspheres is 4.7mL; the amount of ethanol solution added to each 1g of modified chitosan microspheres in step A3 is 12mL, the amount of dioxane added to each 1g of modified chitosan microspheres is 12mL, and the weight ratio of modified chitosan microspheres to catalyst is 1:0.5.

[0067] Preparation Example 2

[0068] A modified chitosan-based chelating resin is prepared. The difference between the modified chitosan-based chelating resin and the preparation example 1 is that the amount of 2-amino-1,3-propanediol added is different. The amount of 2-amino-1,3-propanediol added in the preparation example 2 is 11 kg.

[0069] Preparation Example 3

[0070] A modified chitosan-based chelating resin is prepared. The difference between the modified chitosan-based chelating resin and the preparation example 1 is that the amount of 2-amino-1,3-propanediol added is different. The amount of 2-amino-1,3-propanediol added in the preparation example 2 is 12 kg.

[0071] Example

[0072] Example 1

[0073] A method for preparing lithium carbonate from lithium ore comprises the following steps:

[0074] S1: 2 kg of lithium ore was crushed, ground, and sieved to a particle size of 178 μm to obtain ore powder, which was then subjected to crystal transformation and roasting at 1170°C to obtain a roasted material; after cooling, the ore powder was ground again to a particle size of 72 μm, and then subjected to sulfate roasting at 250°C to obtain an acidified clinker, to which 3 kg of deionized water was added for stirring and leaching, and the mixture was filtered to obtain a leachate;

[0075] S2: Add 0.25 kg of nitrilotriacetic acid, 0.25 kg of diethanolamine, and 0.25 kg of EDTA to the leachate, mix well, filter, collect the filter cake, add 30 L of deionized water to the filter cake, and simultaneously introduce carbon dioxide at a flow rate of 60 L / h for 50 min to obtain a solution containing lithium bicarbonate;

[0076] S3: mixing the solution containing lithium bicarbonate with 3 kg of aminophosphonic acid resin, reacting for 1.5 hours, filtering, and collecting the filtrate to obtain a first mixed solution;

[0077] S4: mixing the first mixed solution with 3 kg of the modified chitosan-based chelating resin prepared in Preparation Example 1, reacting for 1.5 h, filtering, and collecting the filtrate to obtain a second mixed solution;

[0078] S5: Add 5 kg of sodium carbonate to the second mixed solution, mix well, and filter to obtain crude lithium carbonate;

[0079] S6: The crude lithium carbonate is repeatedly washed with deionized water, filtered, and dried to obtain lithium carbonate.

[0080] Example 2

[0081] A method for preparing lithium carbonate from lithium ore, which differs from Example 1 in that the source of the modified chitosan-based chelating resin is different. The modified chitosan-based chelating resin in Example 2 is prepared using Preparation Example 2.

[0082] Example 3

[0083] A method for preparing lithium carbonate from lithium ore, which differs from Example 1 in that the source of the modified chitosan-based chelating resin is different. The modified chitosan-based chelating resin in Example 3 is prepared using Preparation Example 3.

[0084] Example 4

[0085] A method for preparing lithium carbonate from lithium ore, which differs from Example 2 in that, in step S2, after obtaining a solution containing lithium bicarbonate, it is pyrolyzed. The specific method is as follows: heating the solution containing lithium bicarbonate in a water bath at a temperature of 90° C., stirring continuously for 35 minutes, stopping heating, filtering under reduced pressure, and collecting the filtrate to obtain a solution containing lithium bicarbonate after pyrolysis.

[0086] Example 5

[0087] A method for preparing lithium carbonate from lithium ore, which differs from Example 4 in that an aminophosphonic acid resin is treated before use by the following method: soaking the aminophosphonic acid resin in a 10% by mass sodium chloride solution for 20 hours, taking it out, washing it with deionized water until the discharged water is no longer yellow, rinsing the soaked aminophosphonic acid resin from top to bottom with a 5% by mass hydrochloric acid solution, then rinsing it with deionized water to a pH value of 7, then rinsing it from top to bottom with a 4% by mass sodium hydroxide solution, then rinsing it with deionized water to a pH value of 7, and finally washing it once with a 5% by mass hydrochloric acid solution to obtain the treated aminophosphonic acid resin; wherein the amount of sodium chloride solution added to 1g of the aminophosphonic acid resin is 2mL, the amount of hydrochloric acid solution added to 1g of the aminophosphonic acid resin is 1mL, and the amount of sodium hydroxide solution added to 1g of the aminophosphonic acid resin is 1mL.

[0088] Comparative Example

[0089] Comparative Example 1

[0090] A method for preparing lithium carbonate from lithium ore, which differs from Example 1 in that the modified chitosan-based chelating resin in step S4 is replaced by chitosan in equal amounts.

[0091] Comparative Example 2

[0092] A method for preparing lithium carbonate from lithium ore, which differs from Example 1 in that the modified chitosan-based chelating resin in step S4 is replaced by an anion exchange resin, specifically D401, in equal amounts.

[0093] Comparative Example 3

[0094] A method for preparing lithium carbonate from lithium ore, which differs from Example 1 in that the complexing agent in step S2 is any one of nitrilotriacetic acid, diethanolamine, and EDTA.

[0095] Comparative Example 4

[0096] A method for preparing lithium carbonate from lithium ore, which differs from Example 1 in that the complexing agent in step S2 is any two of nitrilotriacetic acid, diethanolamine, and EDTA, and the weight ratio of any two is 1:1.

[0097] Performance testing

[0098] The following performance tests were performed on the lithium carbonate in Examples 1-5 and Comparative Examples 1-4:

[0099] Lithium carbonate content: The purity of lithium carbonate was measured in accordance with GB / T 11075-2013 "Lithium Carbonate". The test results are shown in Table 1.

[0100] Calcium ion content: The calcium ion content was measured in accordance with GB / T 11075-2013 "Lithium Carbonate". The test results are shown in Table 1.

[0101] Magnesium ion content: The magnesium ion content was determined in accordance with GB / T 11075-2013 "Lithium Carbonate". The test results are shown in Table 1.

[0102] Boron content: The boron content was measured in accordance with YS / T 582-2013 "Battery Grade Lithium Carbonate". The test results are shown in Table 1.

[0103] Aluminum ion content: The aluminum ion content was measured in accordance with YS / T 582-2013 "Battery Grade Lithium Carbonate". The test results are shown in Table 1.

[0104] Table 1 Test results

[0105]

[0106] As can be seen from Table 1, the method for preparing lithium carbonate from lithium ore of the present application, through the synergistic effect between each step, not only reduces the content of calcium ions, magnesium ions, aluminum ions, and boron, but also improves the purity of lithium carbonate, wherein the lithium carbonate content is 99.17-99.98%, the calcium ion content is 0.022-0.123%, the magnesium ion content is 0.015-0.068%, the boron content is 0.014-0.073%, and the aluminum ion content is 0.017-0.11%.

[0107] Combining Example 1 and Comparative Examples 1-2, it can be seen that the lithium carbonate content in Example 1 is 99.17%, the calcium ion content is 0.123%, the magnesium ion content is 0.068%, the boron content is 0.073%, and the aluminum ion content is 0.11%, which is better than Comparative Examples 1-2, indicating that the modified chitosan-based chelating resin used in the present application is more suitable, can reduce the content of impurities, increase the content of lithium carbonate, and thus improve the purity of lithium carbonate.

[0108] Combining Example 1 and Comparative Examples 3-4, it can be seen that the lithium carbonate content in Example 1 is 99.17%, the calcium ion content is 0.123%, the magnesium ion content is 0.068%, the boron content is 0.073%, and the aluminum ion content is 0.11%, which is better than Comparative Examples 3-4, indicating that a mixture of nitrilotriacetic acid, diethanolamine, and EDTA in a weight ratio of 1:1:1 in the present application is more suitable as a complexing agent, which can reduce the content of impurities and increase the content of lithium carbonate, thereby improving the purity of lithium carbonate.

[0109] It can be seen from Examples 1-3 that the lithium carbonate content in Example 2 is 99.31%, the calcium ion content is 0.067%, the magnesium ion content is 0.035%, the boron content is 0.037%, and the aluminum ion content is 0.042%, which is better than other embodiments, indicating that the modified chitosan-based chelating resin prepared in Preparation Example 2 is more suitable, can reduce the content of impurities, increase the content of lithium carbonate, and thus improve the purity of lithium carbonate.

[0110] Combining Example 2 and Example 4, it can be seen that the lithium carbonate content in Example 4 is 99.62%, the calcium ion content is 0.051%, the magnesium ion content is 0.019%, the boron content is 0.021%, and the aluminum ion content is 0.024%, which is better than Example 2. This shows that it is more appropriate to pyrolyze the solution containing lithium bicarbonate, which not only reduces the content of calcium ions, magnesium ions, aluminum ions, and boron, but also improves the purity of lithium carbonate.

[0111] Combining Example 4 and Example 5, it can be seen that in Example 5, the lithium carbonate content is 99.98%, the calcium ion content is 0.022%, the magnesium ion content is 0.015%, the boron content is 0.014%, and the aluminum ion content is 0.017%, indicating that it is more appropriate to pretreat the aminophosphonic acid resin before use, which further improves the adsorption capacity, not only reduces the content of calcium ions, magnesium ions, aluminum ions, and boron, but also improves the purity of lithium carbonate.

[0112] The above-mentioned specific implementation examples are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for preparing lithium carbonate from lithium ore, characterized in that: The steps include: S1: pre-treating the lithium ore, adding deionized water, stirring and leaching, and filtering to obtain a leachate; S2: adding a complexing agent to the leachate, mixing uniformly, filtering, collecting the filter cake, and adding deionized water to the filter cake while introducing carbon dioxide to obtain a solution containing lithium bicarbonate; S3: mixing the solution containing lithium bicarbonate with a cationic chelating resin, reacting, filtering, and collecting the filtrate to obtain a first mixed solution; S4: mixing the first mixed solution with the modified chitosan-based chelating resin, reacting, filtering, and collecting the filtrate to obtain a second mixed solution; S5: adding sodium carbonate to the second mixed solution, mixing evenly, and filtering to obtain crude lithium carbonate; S6: repeatedly washing the crude lithium carbonate with deionized water, filtering, and drying to obtain lithium carbonate; The specific method of the pretreatment in step S1 is: crushing, grinding, and screening the lithium ore to obtain ore powder, and performing crystal transformation and roasting on the ore powder to obtain a roasted material; After cooling, grinding again, acidification and roasting are carried out to obtain acidified clinker; The complexing agent in step S2 is a mixture of nitrilotriacetic acid, diethanolamine, and EDTA, and the weight ratio of the three is 1:1:1; The cationic chelating resin in step S3 is an aminophosphonic acid resin; the aminophosphonic acid resin is treated by the following method before use: the aminophosphonic acid resin is immersed in a sodium chloride solution, taken out, washed, and subjected to acid washing, water washing, alkali washing, water washing, and acid washing to obtain the treated aminophosphonic acid resin.

2. The method for preparing lithium carbonate from lithium ore according to claim 1, wherein: In step S2, after obtaining the solution containing lithium bicarbonate, it is pyrolyzed.

3. The method for preparing lithium carbonate from lithium ore according to claim 2, wherein: The specific method of the pyrolysis is as follows: heating the solution containing lithium bicarbonate in a water bath with continuous stirring, stopping the heating after a period of time, filtering under reduced pressure, and collecting the filtrate to obtain a pyrolyzed solution containing lithium bicarbonate.

4. The method for preparing lithium carbonate from lithium ore according to claim 1, wherein: The modified chitosan-based chelate resin in step S4 is prepared by modifying the chitosan-based chelate resin with 2-amino-1,3-propanediol.

5. The method for preparing lithium carbonate from lithium ore according to claim 4, wherein: The modified chitosan chelate resin is prepared by the following method: A1: Place chitosan powder in acetic acid solution, mix well, add sodium hydroxide solution, mix, let stand, filter, wash, and dry to obtain chitosan microspheres; A2: Place chitosan microspheres in deionized water, add isopropyl alcohol, adjust the pH to 9-11, add epichlorohydrin, heat, reflux, filter, wash, and dry to obtain modified chitosan microspheres; A3: Place the modified chitosan microspheres in an ethanol solution, add dioxane, a catalyst, and 2-amino-1,3-propanediol, heat to a high temperature, reflux reaction, filter, wash, and dry to obtain a modified chitosan-based chelating resin.

6. The method for preparing lithium carbonate from lithium ore according to claim 5, wherein: The weight ratio of the chitosan powder to 2-amino-1,3-propanediol is 1:(5-6).

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