Method for producing lithium hydroxide from industrial-grade lithium carbonate

Abstract

The present invention relates to the field of manufacturing technology for battery-grade lithium hydroxide, and more specifically to a method for manufacturing lithium hydroxide using industrial-grade lithium carbonate. The present invention involves acidifying lithium carbonate, mixing it with an alkali, and then performing ultrafiltration; the obtained ultrafiltration product is sequentially subjected to chelation treatment and boron removal treatment; the obtained boron removal resin product is subjected to electrodialysis to obtain ED concentrated water and ED fresh water; the ED concentrated water is treated in an anode membrane system, and the obtained lithium hydroxide feed solution containing sulfate ions is subjected to primary evaporation crystallization after sulfate ion removal to obtain lithium hydroxide; the ED fresh water passes through a membrane concentration system, and the obtained concentrated water is mixed with the ultrafiltration product for reuse; the ED concentrated water is treated in an anode membrane system to produce an acidic solution and a lithium sulfate solution; the acidic solution is reused in the acidification treatment process; and alkali is added to the lithium sulfate solution and mixed with the ultrafiltration product for reuse. The above manufacturing method has high production efficiency and high product quality.

Description

Technology Field

[0001] The present invention relates to the field of manufacturing technology for battery-grade lithium hydroxide, and in particular to a method for manufacturing lithium hydroxide from industrial-grade lithium carbonate. Background Technology

[0002] Currently, while it is possible to directly produce battery-grade lithium hydroxide from lithium ore, refining costs are very high because it requires multiple evaporation and recrystallization steps. Salt lake lithium extraction requires first producing lithium carbonate and then causticizing it to generate lithium hydroxide; therefore, it is not possible to directly produce battery-grade lithium hydroxide beyond the lithium carbonate production stage. In the case of ore lithium extraction, lithium sulfate solution is generated using the roasting and acidification of lithium concentrate. This lithium sulfate is then converted via sodium hydroxide, and battery-grade lithium hydroxide is produced through filtration, evaporation and concentration, crystallization (some undergoing polycrystalline), drying, and other processes. Because the process is complex, consumes a large amount of sodium hydroxide, and requires multiple re-dissolutions and evaporation crystallizations to refine it to battery-grade standards, battery-grade lithium hydroxide produced by the ore method is very energy-intensive and has a very high cost. In the production of battery-grade lithium hydroxide from salt lakes, lithium carbonate is first produced, followed by the production of lithium hydroxide products through the caustic method. However, because the impurity content of the salt lake lithium carbonate itself is high, the quality and consistency of the lithium hydroxide products produced cannot be guaranteed when industrial-grade lithium carbonate is processed using the caustic method. In addition to the caustic method, there is also a process for producing lithium hydroxide through brine electrolysis, but at the current stage, it is still in the testing phase, and the process maturity and product quality are poor. The problem to be solved

[0003] The objective of the present invention is to provide a method for producing lithium hydroxide from industrial-grade lithium carbonate having high production efficiency and high product quality. means of solving the problem

[0004] To achieve the above objective of the present invention, the present invention provides the following technical solution:

[0005] The present invention provides a method for producing lithium hydroxide from industrial-grade lithium carbonate, comprising the following steps:

[0006] Lithium carbonate is acidified to obtain an acidified lithium sulfate solution;

[0007] After mixing the above acidified lithium sulfate solution with alkali, ultrafiltration is performed to obtain ultrafiltered water;

[0008] The above-mentioned ultrafiltration product is sequentially chelated using a chelating resin and boron removal treatment is performed using a boron removal resin to obtain a boron removal resin product;

[0009] The above boron removal resin-generated water is subjected to electrodialysis to obtain ED concentrated water and ED fresh water;

[0010] After treating the above ED concentrate in an anode membrane system, lithium hydroxide containing sulfate ions, an acidic solution, and a lithium sulfate solution are obtained;

[0011] The lithium hydroxide supply solution containing the above sulfate ions is treated to remove the sulfate ions in order to obtain the above lithium hydroxide solution;

[0012] The lithium hydroxide solution is subjected to primary evaporation and crystallization to obtain the lithium hydroxide;

[0013] The above ED fresh water passes through a membrane concentration system to obtain a concentrated liquid, is mixed with ultrafiltered generated water, and is reused;

[0014] The above acidic solution is reused in the acidification treatment process, and the above lithium sulfate solution is reused by adding alkali and mixing it with ultrafiltered water.

[0015] Preferably, the acidic solution used in the acidification treatment is dilute sulfuric acid, and the mass concentration of the dilute sulfuric acid is 4.9%;

[0016] After the above acidification treatment is stably performed, it comprises lithium carbonate, dilute sulfuric acid, and water; the usage ratio of the lithium carbonate, dilute sulfuric acid, and water is 0.9~1.1t: 2.90~3.50m 3 : 23~27m 3 am.

[0017] Preferably, the pH value of the mixed solution obtained after mixing the acidified lithium carbonate solution and alkali is 9 to 11.

[0018] Preferably, the chelate resin is an aminophosphonic acid resin and / or an iminodiacetic acid resin;

[0019] The above chelate resin is packed into a resin column, and the adsorption flow rate is 4 to 8 BV / h.

[0020] Preferably, the boron removal resin comprises polyhydroxylamine groups;

[0021] The pH of the above boron removal treatment is 5 to 14.

[0022] Preferably, the membrane groups of the bipolar membrane system are all symmetric ion membranes;

[0023] The operating voltage of each bipolar membrane set is 1.0–2.0 V and the current density is 200–800 A / m² 2 am.

[0024] Preferably, the ion exchange membrane used for the above electrodialysis is a bio-ionic membrane.

[0025] Preferably, when processed in a bipolar membrane system, the concentration of the ED concentrate is ≥8 wt% and the concentration of the lithium sulfate solution is ≥4 wt%.

[0026] Preferably, the sulfate ion removal is performed by separating sulfate ions using a nanofiltration membrane;

[0027] The operating pressure for the above sulfate ion removal is 2 to 6 MPa.

[0028] Preferably, the evaporator for the primary evaporation and crystallization uses an MVR;

[0029] The above primary evaporation and crystallization include evaporative concentration and cooling crystallization performed sequentially;

[0030] The above evaporation concentration temperature is 75~105℃, and the temperature after cooling crystallization is <40℃.

[0031] The present invention provides a method for producing lithium hydroxide from industrial-grade lithium carbonate, comprising the following steps: acidifying lithium carbonate to obtain an acidified lithium sulfate solution; mixing the acidified lithium sulfate solution with an alkali and then performing ultrafiltration to obtain an ultrafiltered water;

[0032] The above ultrafiltered water is sequentially chelated using a chelating resin, and boron removal treatment is performed using a boron removal resin to obtain boron removal resin-produced water;

[0033] The above boron removal resin-generated water is subjected to electrodialysis to obtain ED concentrated water and ED fresh water;

[0034] After treating the above ED concentrated water in an anode membrane system, lithium hydroxide containing sulfate ions, an acidic solution, and a lithium sulfate solution are obtained; the lithium hydroxide solution is obtained by removing sulfate ions from the above lithium hydroxide feed solution containing sulfate ions; the lithium hydroxide solution is obtained by primary evaporation and crystallization; the above ED fresh water is passed through a membrane concentration system to obtain a concentrated liquid, which is mixed with ultrafiltered water and reused; the above acidic solution is reused in the above acidification treatment process, and the above lithium sulfate solution is reused by adding alkali and mixing it with ultrafiltered water. Effects of the invention

[0035] Compared to existing technology, the technical solution described in the present invention has the following beneficial effects.

[0036] 1) The present invention produces lithium hydroxide using an anode film, and has a higher production efficiency compared to other lithium hydroxide production methods.

[0037] 2) Manufacturing lithium hydroxide using a positive electrode is an economical and environmentally friendly production process.

[0038] 3) The technology is safe and highly reliable.

[0039] 4) The quality of lithium hydroxide produced by this process is better. Brief explanation of the drawing

[0040] Figure 1 is a schematic diagram of a lithium hydroxide manufacturing process according to the present invention. Specific details for implementing the invention

[0041] The present invention provides a method for producing lithium hydroxide from industrial-grade lithium carbonate comprising the following steps:

[0042] Lithium carbonate is acidified to obtain an acidified lithium sulfate solution;

[0043] After mixing the above acidified lithium sulfate solution with alkali, ultrafiltration is performed to obtain ultrafiltered water;

[0044] The above-mentioned ultrafiltered water is sequentially chelated using a chelating resin, and boron removal treatment is performed using a boron removal resin to obtain boron removal resin-derived water;

[0045] The above boron removal resin-generated water is subjected to electrodialysis to obtain ED concentrated water and ED fresh water;

[0046] After treating the above ED concentrate in an anode membrane system, lithium hydroxide containing sulfate ions, an acidic solution, and a lithium sulfate solution are obtained;

[0047] The lithium hydroxide supply solution containing the above sulfate ions is treated to remove the sulfate ions in order to obtain the above lithium hydroxide solution;

[0048] The lithium hydroxide solution is subjected to primary evaporation and crystallization to obtain the lithium hydroxide;

[0049] The above ED fresh water passes through a membrane concentration system to obtain a concentrated liquid, is mixed with ultrafiltered water, and is reused;

[0050] The above acidic solution is reused in the acidification treatment process, and the above lithium sulfate solution is reused by adding alkali and mixing it with ultrafiltered water.

[0051] Unless otherwise specifically stated, all manufacturing materials in this invention are commercially available products well known to those skilled in the art.

[0052] In the present invention, lithium carbonate is acidified to obtain an acidified lithium sulfate solution.

[0053] In the present invention, the acidification treatment process preferably involves pre-injecting water, lithium carbonate, and concentrated sulfuric acid into the reaction facility during the initial pre-injection stage to perform oxidation treatment, taking into account issues such as congestion in the pipeline, reaction facility, and concentration circulation pipe. After stable operation, there is no need to continuously inject concentrated sulfuric acid, and the acidic solution is replaced and replenished with an acidic solution (dilute sulfuric acid) obtained through ion exchange in an anode membrane system. In the present invention, the purity of the lithium carbonate is preferably 99%. The lithium carbonate also preferably comprises 0.15 wt% sodium ions, 0.0015 wt% magnesium ions, 0.04 wt% calcium ions, 0.35 wt% sulfate ions, 0.01 wt% chloride ions, 0.035 wt% iron-containing ions, and 0.015 wt% salts and insoluble substances. In the present invention, the mass percentage concentration of the concentrated sulfuric acid is preferably 98 wt%. In the present invention, during the acidification treatment process, sulfuric acid reacts with lithium carbonate to produce lithium sulfate, carbon dioxide, and water. In the present invention, during the initial pre-injection stage, the pre-injection ratio of lithium carbonate, concentrated sulfuric acid, and water within the reaction facility is 0.9~1.13t: 1.32~1.60t: 26~32m 3 After the acidification treatment has proceeded stably, the input ratio of lithium carbonate, dilute sulfuric acid, and water to the acidification treatment system is preferably 0.9~1.1t:23~27m 3 :2.90~3.50m 3In the present invention, the input ratio (volume ratio) of the lithium carbonate, concentrated sulfuric acid, and water is preferably the consumption ratio of lithium hydroxide monohydrate per ton.

[0054] In the present invention, the total dissolved solids (TDS) content in the acidified lithium sulfate solution is preferably 4.9 wt%, i.e., 50,000 mg / L.

[0055] After obtaining the above acidified lithium sulfate solution, the present invention obtains ultrafiltered water by mixing the above acidified lithium sulfate solution with an alkali and then performing ultrafiltration treatment.

[0056] In the present invention, after obtaining the acidified lithium sulfate solution, preferably, a plate frame filter press is performed on the acidified lithium sulfate solution to obtain a filtrate and a filter cake, the filtrate is refluxed into the acidified lithium sulfate solution; and the filter cake is treated as solid waste.

[0057] In the present invention, the base is preferably lithium hydroxide. In the present invention, there is no special limitation on the amount of alkali used, and the pH value of the resulting mixture is adjusted to 9.5 to 10.5 using an amount known to those skilled in the art, and more preferably, the pH value of the resulting mixture is adjusted to 10.

[0058] In the present invention, the process of mixing with the alkali is preferably carried out by using a precipitation method, in which some expensive metal ions (such as iron-containing ions) in the acidified lithium sulfate solution precipitate in the form of hydroxide precipitates.

[0059] The method further includes the step of, after mixing with the alkali, transferring the obtained product system to a concentration circulation tank and ultrafiltration the lithium sulfate feed solution in the concentration circulation tank.

[0060] In the present invention, the inlet pressure of the ultrafiltration treatment is preferably 0.3 MPa, and the ultrafiltration treatment filters insoluble substances and precipitates in the filtrate to improve the inlet water quality of the anode membrane and protect the anode membrane system.

[0061] In the present invention, the feed liquid containing a large amount of impurities is preferably fed into a plate frame filter press system and filtered by a plate frame filter press, the obtained filtrate is returned to a process of mixing with alkali in the above technical method, and the obtained filter cake is treated as solid waste.

[0062] In the present invention, the iron ion concentration in the acidified lithium sulfate solution is preferably 10 to 20 mg / L, and the insoluble substance is preferably 5 to 10 mg / L; the concentration of the suspension (SS) of the ultrafiltered water produced after the ultrafiltration treatment is preferably <1 mg / L, and the iron ion concentration is reduced to 0.5 to 4.0 mg / L.

[0063] After obtaining the ultrafiltered water product, the present invention sequentially chelates the ultrafiltered water using a chelating resin and performs boron removal treatment using a boron removal resin to obtain boron removal resin product water.

[0064] In the present invention, the functional group of the chelate resin is preferably an iminodiacetic acid group, iminodiacetic acid, aminocarboxylic acid and aminophosphonic acid, aminoacetic acid, or aminomethylphosphate. When the functional group of the chelate resin is an iminodiacetic acid group, the model of the chelate resin is specifically Zhengguang-D851 (framework structure is macroporous styrene-divinylbenzene, phytoform is Na+, applicable pH is 1.5 to 14); and when the functional group of the chelate resin is iminodiacetic acid, the model of the chelate resin is Su Qing-D402 (framework structure is macroporous styrene, phytoform is Na+, applicable pH is 3 to 11); When the functional groups of the above chelate resin are aminocarboxylic acid and aminophosphonic acid, the specific model of the chelate resin is Lanxiao 930 (the skeletal structure is a macroporous polystyrene molecule, the plant form is Na+, and the applicable pH is 2 to 7); when the functional group of the above chelate resin is glycine, the model of the chelate resin is HP-HP4040 (plant form Na+, applicable pH is 8 to 10); and when the functional group of the above chelate resin is aminomethylphosphate, the specific model of the above chelate resin is HP-HP706 (plant form Na+, applicable pH is 8 to 10). In the present invention, the chelation treatment is preferably a multi-stage chelation treatment, and the multi-stage chelation treatment undergoes a three-stage hard removal treatment sequentially through a first chelation resin column, a second chelation resin column, and a third chelation resin column, wherein the chelation resins of the first chelation resin column, the second chelation resin column, and the third chelation resin column are preferably the same.

[0065] In the present invention, the chelation treatment conditions are preferably such that the volumetric flow rate of the ultrafiltered water is preferably 4 to 8 BV / h.

[0066] In the present invention, the chelating resin selectively chelates a polymer compound of a specific metal ion in the form of an ionic bond or a coordination bond from a lithium sulfate solution containing metal ions, and reduces the iron ions, magnesium ions, calcium ions, and other unmentioned heavy metal ions contained in the ultrafiltered water to a sum of calcium and magnesium < 0.5 mg / L and a sum of iron and other heavy metal ions < 1 mg / L.

[0067] In the present invention, when ion exchange occurs, the chelate resin selectively chelates specific calcium, magnesium, iron, and other heavy metal ions in the form of ionic or coordinate bonds to release lithium ions, thereby removing heavy metal ions from the ultrafiltration product water. Therefore, when regenerating the chelate resin after the chelation treatment, it is modified using lithium hydroxide.

[0068] In the present invention, the functional group of the boron removal resin is preferably N-methylglucamine, -N(CH3)--CH2-(CHOH)4-CH2OH, a boron coordinating group, or meglumine; when the functional group of the boron removal resin is preferably N-methylglucamine, the model of the boron removal resin is specifically Zhengguang-D870B (the skeletal structure is styrene-based, the plant form has free hydroxyl groups, and is applicable to pH ≤ 10); and when the functional group of the boron removal resin is preferably -N(CH3)--CH2-(CHOH)4-CH2OH, the specific model of the boron removal resin is Lanxiao-LSC-800 (the skeletal structure is a macroporous styrene-divinylbenzene copolymer, the plant form is free ammonia, and is applicable to pH ≤ 10); When the functional group of the boron removal resin is preferably a boron coordination group, the model of the boron removal resin is HP-HPB119 (the skeletal structure is polystyrene having a macroporous structure, applicable to pH 5 to 14); when the functional group of the boron removal resin is meglumine, the specific model of the boron removal resin is Zhengguang D403 (the skeletal structure is styrene-based, the plant type is free amine type, applicable to pH 8 to 10).

[0069] In the present invention, the boron removal treatment condition is preferably such that the volumetric flow rate of the chelate generated water after the chelation treatment is preferably 4 to 8 BV / h.

[0070] In the present invention, the boron removal resin can adsorb and remove boron ions from a lithium sulfate solution containing boron ions, and can reduce the boron ions in the chelate-produced water to 1 mg / L or less.

[0071] In the present invention, when the boron removal resin performs ion exchange, the boron removal resin removes heavy metal ions in the lithium sulfate supply solution by adsorbing boron ions in the supply solution; therefore, when regenerating the boron removal resin after boron removal treatment, it should preferably be interpreted as an acid solution.

[0072] After obtaining the boron removal resin-generated water, the present invention electrodialyzes the boron removal resin-generated water to obtain ED concentrated water and ED fresh water.

[0073] In the present invention, the electrodialysis preferably uses a uniaxial ion membrane; the negative membrane model used for the electrodialysis is specifically Create-AN (framework structure: co-spinning of three materials: PEEK, PP, and PE; membrane substrate: styrene-PP / PE copolymer; group: quaternary ammonium type; applicable pH 1 to 14); and the positive membrane model used for the electrodialysis is specifically Create-CN (framework structure: co-spinning of polyaromatic hydrocarbons and polyethylene; membrane substrate: styrene-PP / PE copolymer; group: sulfonic acid type; applicable pH 1 to 14). In the present invention, the current density of the electrodialysis is preferably 100 to 500 A / m² 2 and, more preferably 150~350 A / m 2 , most preferably 200~300 A / m 2 And, the operating voltage of each pair of membranes is preferably 0.5 to 1.0 V, more preferably 0.6 to 0.9 V, and most preferably 0.7 to 0.8 V.

[0074] In the present invention, electrodialysis refers to a membrane separation technology in which charged ions in a solution move directionally under the action of a DC electric field and are selectively removed by passing through an ion exchange membrane. It is a physical and chemical process that utilizes the selective permeability of anion and cation exchange membranes for anions and cations, driven by a potential difference, to cause ions to move from one part of water to another. The electrodialysis membrane module consists of a separation membrane, an ion exchange membrane, electrodes, a clamping device, and other key components. The ion exchange membrane can selectively permeate ions of different charges. A cation membrane allows only cations to pass through while blocking anions; an anion membrane allows only anions to pass through while blocking cations. Under the action of an external DC electric field, ions in the water move in a specific direction. Since the membrane module is composed of multi-layered compartments, anions and cations from the dilution chamber move to the adjacent concentration chamber to desalinate the brine.

[0075] In the present invention, the mass percentage concentration of lithium sulfate in the boron removal resin-produced water is preferably 5 wt%, the mass percentage concentration of the ED concentrated water is preferably 8 wt% or more, and the mass percentage concentration of the ED fresh water is preferably 1.5 to 2%.

[0076] After obtaining the above ED concentrated water, the present invention processes the above ED concentrated water in an anode membrane system to obtain lithium hydroxide containing sulfate ions, an acidic solution, and a lithium sulfate solution; the lithium hydroxide feed solution containing sulfate ions undergoes a sulfate ion removal process to obtain the lithium hydroxide solution.

[0077] In the present invention, the membrane group of the bipolar membrane system is preferably a symmetric ion membrane; in the present invention, the cathode membrane model of the bipolar membrane system is specifically Create-A2N (framework structure: co-spinning of three materials: PEEK, PP, and PE; membrane substrate: methylethylpropylbutyl quaternary ammonium secondary ammonium type); the anode membrane model of the bipolar membrane system is specifically Create-C2N (framework structure: polyaromatic and polyethylene co-spinning; membrane substrate: styrene PP / PE copolymer; functional groups: sulfonic acid type / phosphate type); and the anode membrane model of the bipolar membrane system is specifically Create-BP (membrane substrate: styrene PP / PE copolymer; functional groups: quaternary ammonium sulfonic acid type). In the present invention, the operating voltage of each bipolar membrane group is preferably 1.0 to 2.0 V, more preferably 1.2 to 1.8 V, and most preferably 1.4 to 1.6 V; and the current density is preferably 200 to 800 A / m² 2 , more preferably 300~700 A / m 2 , most preferably 400~600 A / m 2 am.

[0078] In the present invention, when a feed solution flows into the salt chamber, anions move through the cathode membrane to the acid chamber under the action of a DC electric field and come into contact with the surface of the anode membrane of the anode membrane; since the surface of the anode membrane carries a negative charge, the anions cannot continue to move and remain in the acid chamber, where they combine with hydrogen ions decomposed on the surface of the anode membrane of the anode membrane to produce acid. Under the action of a DC electric field, the surface of the cathode membrane of the anode membrane continuously decomposes hydroxide ions and combines with cations in the alkali chamber to produce an alkaline liquid. The final salt solution is converted into acid and base through anode membrane electrodialysis. The anode membrane electrodialysis treatment system (i.e., anode membrane electrodialysis system) preferably comprises an anode, an anode membrane, a plurality of repeating membrane units, a cathode membrane, and a cathode arranged in order from left to right; One membrane unit preferably arranges a positive membrane, an anion exchange membrane, a cation exchange membrane, and a positive membrane in sequence, and there is a salt chamber between the anion exchange membrane and the cation exchange membrane, an acid chamber between the positive membrane and the anion exchange membrane, and an alkali chamber between the positive membrane and the cation exchange membrane.

[0079] In the present invention, the mass concentration of the lithium sulfate solution is preferably ≥4 wt%, more preferably 4 to 6 wt%, and the pH of the lithium sulfate solution is preferably 1. In the present invention, the acidic solution is preferably purified water as the contact solution, and sulfuric acid with a hydrogen ion concentration of 1 mol / L and a sulfuric acid content of 49 g / L is obtained. In the present invention, the lithium hydroxide containing sulfate ions is preferably purified water as the contact solution, and an alkaline solution with a hydroxide ion content of 1 mol / L and a lithium hydroxide content of 24 g / L is obtained. In the present invention, the lithium sulfate solution is preferably reused by adding an alkali to adjust the pH to 10 and mixing it with ultrafiltered water, and in the present invention, the alkali is preferably a lithium hydroxide solution.

[0080] In the present invention, the sulfate ion removal is preferably performed by separating sulfate ions using a nanofiltration membrane, the operating pressure of the sulfate ion removal is preferably 2 to 6 MPa, more preferably 3 to 5 MPa, most preferably 4 MPa, and the water recovery rate is preferably 70 to 90%, more preferably 75 to 85%, and most preferably 78 to 82%.

[0081] In the present invention, the concentration of lithium hydroxide in the lithium hydroxide solution is preferably 24 g / L, and the concentration of sulfate ions is preferably less than 200 mg / L.

[0082] After the above-mentioned sulfate ion removal is completed, the present invention preferably includes the step of obtaining a concentrated water from the sulfate ion removal system; the concentrated water from the sulfate ion removal system is introduced into a neutralization tank and neutralized with an acid solution and an external acid to obtain a neutralized feed solution, after which the neutralized feed solution enters the concentration process described in the above-mentioned technical method and is reused.

[0083] In the present invention, the ED fresh water passes through a membrane concentration system to obtain a concentrated liquid, which is returned to an ultrafiltration process and subjected to ultrafiltration; in the present invention, the total salt mass percentage of the ED fresh water is preferably 1.5 to 2%, more preferably 1.6 to 1.8%. In the present invention, the concentration pressure is preferably 2 to 6 MPa, more preferably 3 to 5 MPa; the water recovery rate is preferably 50 to 80%, more preferably 55 to 75%, and most preferably 60 to 70%. The mass percentage of the total salt content of the concentrate obtained after concentration is preferably 4% to 6%, more preferably 4.5% to 5.5%, and most preferably 4.8% to 5.2%.

[0084] In the present invention, the acidic solution is reused in the acidification treatment process; and the lithium sulfate solution is reused by adding alkali to ultrafiltered water.

[0085] After obtaining the above lithium hydroxide solution, the present invention obtains the lithium hydroxide by first evaporating and crystallizing the above lithium hydroxide solution.

[0086] In the present invention, the evaporator for the primary evaporation crystallization preferably uses an MVR; the primary evaporation crystallization preferably includes sequential evaporation concentration and cooling crystallization; the temperature of the evaporation concentration is preferably 70 to 105°C, more preferably 75 to 85°C, and the temperature after cooling and crystallization is preferably <40°C, more preferably room temperature.

[0087] Hereinafter, a method for manufacturing lithium hydroxide using industrial-grade lithium carbonate provided by the present invention will be specifically described with reference to examples, but the scope of the present invention should not be interpreted as being limited thereto.

[0088] Example 1

[0089] As shown in FIG. 1, industrial-grade lithium carbonate (purity is 99%. The lithium carbonate contains 0.15 wt% sodium ions, 0.0015 wt% magnesium ions, 0.04 wt% calcium ions, 0.35 wt% sulfate ions, 0.01 wt% chloride ions, 0.035 wt% iron-containing ions, and 0.015 wt% salts and insoluble substances), a pre-injection amount of concentrated sulfuric acid with a mass concentration of 98% and water (the pre-injection ratio of lithium carbonate, concentrated sulfuric acid, and water is 1.37 t:1.92 t:38.71 m 3 (is) is added to the reaction kettle, acidification treatment is carried out, and after stable operation, the addition of concentrated sulfuric acid is stopped, and the acidic solution is replaced and replenished with an acidic solution (dilute sulfuric acid) obtained through ion exchange in an anode membrane system (after the acidification treatment has operated stably, the dosage ratio of lithium carbonate, dilute sulfuric acid, and water in the acidification treatment system is preferably 1.22t:32.72m3:4.22m 3is), an acidified lithium sulfate solution is obtained (the total dissolved solids (TDS) content is 4.9 wt%, i.e., 50,000 mg / L, the iron ion concentration is 60 mg / L, and the SS concentration is 0.01%);

[0090] The above acidified lithium sulfate solution is placed in a reaction kettle, lithium hydroxide is added to adjust the pH to 10, and then enters a concentration circulation tank to concentrate it, thereby obtaining a suitable raw material liquid (lithium sulfate raw material liquid) and a raw material liquid containing more impurities; the raw material liquid containing more impurities enters a plate frame filter press system to obtain a filtrate and a filter cake, the filtrate is reused in the mixing process with the alkali mentioned above, and the filter cake is outsourced; the accepted raw material liquid is placed in an ultrafiltration system and subjected to ultrafiltration (the ultrafiltration inlet pressure is 0.3 MPa) to filter out insoluble substances and precipitates in the filtrate, thereby obtaining ultrafiltered water (iron ion concentration <0.1 ppm);

[0091] The above ultrafiltration product passes through three aminophosphonic acid resins in succession (specifically the model is Su Qing-D402 (the skeletal structure is macroporous styrene, and the plant form is Na) + (, pH 3~11 applied), the column was subjected to a 3-stage chelation treatment (the volumetric flow rate of the ultrafiltered water is 4 BV / h), and chelated water was obtained (the total concentration of calcium and magnesium is 0.5 ppm, and the total concentration of iron and other heavy metal ions is 0.1 ppm);

[0092] The above chelated water is passed through the boron removal resin of a boron removal resin column (the boron removal resin model is Lanxiao-LSC-800) and boron removal treatment is performed (the boron removal treatment conditions are that the pH of the influent water is neutral or weakly alkaline, and the volumetric flow rate of the chelated water is 4 BV / h), and boron removal resin product water is obtained (the boron ion concentration is 1 mg / L);

[0093] The above boron removal resin-generated water is treated by electrodialysis (the ion exchange membrane used in the above electrodialysis treatment is a bio-bed ion membrane (specifically, the cathode membrane model is Create-AN, and the anode membrane model is specifically Create-CN), and the current density is 400 A / m² 2 , the operating voltage of each pair of membranes is <0.05 MPa), ED concentrated water (mass concentration of lithium sulfate is 12%) and ED fresh water (mass percentage concentration of lithium sulfate is 1%) are obtained; the ED fresh water is concentrated through the membrane concentration system (the concentration pressure is 5 MPa, and the water recovery rate is 75%) to obtain a concentrate (mass percentage content of lithium sulfate is 5%), and the process is returned to the ultrafiltration treatment process to perform ultrafiltration;

[0094] The above ED concentrate is processed in a bipolar membrane system (the bipolar membrane group of the bipolar membrane system is a balanced ion membrane, the anion membrane model is Create-A2N, the anode membrane model is Create-C2N, and the bipolar membrane model is Create-BP, and in the above ion exchange process, the operating voltage of each pair of bipolar membranes is 2V and the current density is 800A / m² 2 is), a lithium sulfate solution (the mass concentration of lithium sulfate is 4%, and the pH is 1), an acidic solution, and an alkaline solution were obtained; the acidic solution was obtained by using purified water as the contact solution to obtain sulfuric acid with a hydrogen ion concentration of 1 mol / L and a sulfuric acid content of 49 g / L; the alkaline solution was obtained by using purified water as the contact solution to obtain an alkaline solution with a hydroxide ion content of 1 mol / L and a lithium hydroxide content of 24 g / L;

[0095] Alkaline (lithium hydroxide) is added to the lithium sulfate supply solution to adjust the pH of the lithium sulfate supply solution to 10, and then the solution is introduced into an ultrafiltration water production tank to perform ultrafiltration treatment (the ultrafiltration treatment condition is to adjust the operating pressure to 0.3 MPa); the water produced through the ultrafiltration treatment is used as a raw material for a subsequent sulfate removal system to perform sulfate ion removal (the sulfate ion removal is performed by separating sulfate ions using a nanofiltration membrane, with an operating pressure of 3 MPa and a water recovery rate of 80%), and a lithium hydroxide solution is obtained (lithium hydroxide concentration is 24 g / L, sulfate ion concentration is 50 ppm);

[0096] The above lithium hydroxide solution was subjected to primary evaporation crystallization (the above primary evaporation crystallization includes sequential evaporation concentration and cooling crystallization; the temperature of the evaporation concentration is 85℃ and the temperature of the cooling crystallization is room temperature at 15℃ / h) to obtain lithium hydroxide (the above lithium hydroxide can reach battery levels), and the annual production volume was 10,598.55 tons (based on lithium hydroxide monohydrate).

[0097] The above is merely a preferred embodiment of the present invention, and those skilled in the art may make various improvements and modifications within the scope of the principles of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

Claim 1 Lithium carbonate is acidified to obtain an acidified lithium sulfate solution; the acidified lithium sulfate solution is mixed with an alkali, followed by ultrafiltration to obtain ultrafiltered water; the ultrafiltered water is sequentially chelated using a chelating resin and boron removed using a boron removal resin to obtain boron removal resin-derived water; the boron removal resin-derived water is subjected to electrodialysis to obtain ED concentrated water and ED fresh water; the ED concentrated water is treated in an anode membrane system to obtain lithium hydroxide containing sulfate ions, an acidic solution, and a lithium sulfate solution; the lithium hydroxide feed solution containing sulfate ions is subjected to sulfate ion removal to obtain the lithium hydroxide solution; the lithium hydroxide solution is subjected to primary evaporation and crystallization to obtain the lithium hydroxide; the ED fresh water passes through a membrane concentration system to obtain a concentrated liquid, which is mixed with the ultrafiltered water and reused; the acidic solution is reused up to the acidification treatment process, and the A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized by including the step of reusing a lithium sulfate solution by adding alkali and mixing it with ultrafiltered water. Claim 2 In claim 1, the acidic solution used for the acidification treatment is dilute sulfuric acid, and the mass concentration of the dilute sulfuric acid is 4.9%; and after the acidification treatment is stably carried out, the amount of lithium carbonate used to produce 1 ton of lithium hydroxide monohydrate is 0.9 to 1.1 tons, and the amount of dilute sulfuric acid used is 2.90 to 3.50 m³ 3 and the water usage is 23~27m 3 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized by the fact that Claim 3 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, the pH value of the mixed solution obtained after mixing the acidified lithium carbonate solution with an alkali is 9 to 11. Claim 4 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, the chelate resin is an aminophosphonic acid resin and / or an iminodiacetic acid resin; and the chelate resin is packed into a resin column and the adsorption flow rate is 4 to 8 BV / h. Claim 5 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, the boron removal resin comprises polyhydroxylamine groups; and the pH of the boron removal treatment is 5 to 14. Claim 6 In claim 1, the membrane groups of the bipolar membrane system are all balanced ion membranes; the operating voltage of each bipolar membrane set is 1.0 to 2.0 V and the current density is 200 to 800 A / m² 2 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized by the fact that Claim 7 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, the ion exchange membrane used for electrodialysis is a bio-bed ion membrane. Claim 8 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, when processed in an anode membrane system, the concentration of the ED concentrate is 8 wt% or more and the concentration of the lithium sulfate solution is 4 wt% or more. Claim 9 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, the sulfate ion removal separates sulfate ions using a nanofiltration membrane; and the operating pressure of the sulfate ion removal is 2 to 6 MPa. Claim 10 A method for producing lithium hydroxide from industrial-grade lithium carbonate, characterized in that, in claim 1, the evaporator for the primary evaporation and crystallization uses an MVR; the primary evaporation and crystallization includes evaporation concentration and cooling crystallization performed sequentially; and the evaporation concentration temperature is 75 to 105°C and the temperature after cooling crystallization is less than 40°C.

Images