Process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate

Abstract

The invention discloses a process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate, which comprises the steps of extracting lithium chloride from organic reaction wastewater and preparing lithium carbonate from the obtained industrial-grade lithium chloride, adding lithium chloride to anhydrous ethanol and stirring at a constant temperature until completely dissolved to obtain lithium chloride ethanol solution, adding sodium hydroxide ethanol solution to the lithium chloride ethanol solution, and obtaining a suspended alcohol solution through ultrasonic reaction, and cooling and filtering after reduced pressure distillation reaction to obtain a mixed precipitate, heating distilled water and slowly adding it to the mixed precipitate, washing with anhydrous ethanol for several times and drying to obtain lithium carbonate, utilizing the difference in solubility of lithium carbonate and sodium chloride to realize rapid impurity removal of lithium carbonate to obtain lithium carbonate with higher purity, and utilizing the solubility of lithium chloride and sodium hydroxide in ethanol, supplemented by the insolubility of sodium chloride and lithium carbonate in ethanol, to achieve the effect of promoting the reaction.

Description

Technical Field

[0001] The invention relates to the technical field of battery-grade lithium carbonate preparation, and specifically to a process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate. Background Art

[0002] Lithium carbonate is a basic compound of lithium with a variety of industrial uses. It is widely used in ceramics, glass, atomic energy, aerospace, military industry, refrigeration, welding, lithium alloys, lithium batteries, controlled nuclear fusion reactors, medicine and other fields. In addition, lithium carbonate, as a basic raw material for lithium, can be converted into a variety of other lithium compounds. Battery-grade lithium carbonate is mainly used to produce lithium cobalt oxide, lithium iron phosphate, lithium nickel oxide, lithium manganese oxide or nickel cobalt manganese oxide and other lithium-ion battery positive electrode materials. Its market demand is increasing, and the global demand for lithium carbonate is increasing at an annual rate of 8%. Battery-grade lithium carbonate is mainly produced by the lithium sulfate transformation method produced by the spodumene sulfuric acid method, the lithium hydroxide carbonization method, and the deep carbonization of lithium carbonate into lithium bicarbonate and then lithium hydroxide precipitation method. Battery-grade lithium carbonate is silvery white and easily reacts with oxygen and nitrogen in humid air. It reacts with water and burns or explodes violently when it encounters fire.

[0003] As the demand for lithium continues to rise, global lithium resources are becoming increasingly scarce, and the production of lithium-containing products will produce a large amount of wastewater and waste residue. These wastewater and waste residues are rich in lithium, and recycling them to extract lithium has extremely high economic benefits;

[0004] In the production of lithium fluoride, a large amount of waste liquid containing Li+ and F- ions is generated. Direct discharge of these waste liquids is not only polluting but also a waste of resources. In addition, conventional methods often use dispersants as auxiliary materials for rapid dispersion. However, the addition of dispersants not only causes changes in the reaction system, but also brings certain impurities, resulting in a decrease in the purity of lithium carbonate and difficulty in recovering the lithium therein, which results in a huge waste of resources. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] Therefore, the purpose of the present invention is to provide a process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate, which can deeply remove impurities from the lithium-containing solution to achieve industrial-grade industrial-grade lithium chloride, and further extract the waste generated in the preparation process, thereby increasing resource utilization and reducing resource waste.

[0007] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0008] The process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate comprises the following steps:

[0009] (1) Extraction: Extract lithium chloride from organic reaction wastewater;

[0010] S1. placing organic wastewater in a reaction kettle, adding solid barium carbonate to the organic wastewater for stirring, heating the mixture to 60-70° C. during the stirring process, and performing a preliminary static precipitation operation after the heating reaction is completed to obtain a lithium-containing mixed solution;

[0011] S2, adding 30% liquid caustic soda to the lithium-containing mixed solution prepared in step S1 to make its pH reach 9-13, stirring and heating, and after the temperature reaches 95°C, evenly adding soda ash solution, the concentration of sodium carbonate in the soda ash solution is 200-260g / L, and maintaining the temperature of the reactor at 90-100°C during the addition process. After adding the soda ash solution, keep the temperature constant for 1-2 hours, and then perform a secondary static precipitation operation after the constant temperature;

[0012] S3, filtering the mixed solution obtained in step S2 to obtain a lithium chloride solution and a filter residue, performing an evaporation and concentration operation on the lithium chloride solution to obtain a lithium chloride slurry, and performing a drying operation on the lithium chloride slurry to obtain industrial grade lithium chloride.

[0013] (2) The first preparation method is to prepare lithium carbonate from the obtained industrial-grade lithium chloride:

[0014] A1. Add lithium chloride to anhydrous ethanol and stir at a constant temperature of 90-100°C until it is completely dissolved to obtain lithium chloride ethanol solution;

[0015] A2, adding sodium hydroxide ethanol solution to the lithium chloride ethanol solution prepared in A1, and introducing carbon dioxide gas at the same time, obtaining a suspended alcohol solution through ultrasonic reaction, and cooling and filtering after vacuum distillation to obtain a mixed precipitate;

[0016] A3. Heat distilled water and slowly add it to the mixed precipitate until the precipitate is continuously reduced to obtain a suspension, filter while hot to obtain lithium carbonate precipitate, wash with anhydrous ethanol several times and then dry to obtain lithium carbonate.

[0017] (3) The second preparation method is to prepare lithium carbonate from the obtained industrial-grade lithium chloride;

[0018] B1. Mix lithium chloride, sodium potassium sulfate mixed salt additive and calcium carbonate in a certain proportion through a ball mill, and then granulate them through a granulator. The granulated mixed solid is sent to a rotary kiln for roasting. After the roasted material is cooled, it is wet-milled in a ball mill.

[0019] B2, placing the raw material after wet grinding in step B1 into a leaching kettle, adding circulating water for heating and immersion, maintaining a constant temperature during the immersion process, and obtaining a lithium sulfate mother liquor;

[0020] B3, adding a neutralizing liquid auxiliary agent to the lithium sulfate mother liquor in B2 to neutralize and remove impurities, evaporating and concentrating, adding to a saturated sodium carbonate solution, and precipitating lithium to obtain a crude lithium carbonate product;

[0021] B4. The crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate.

[0022] (4) waste preparation and extraction, further extracting the waste and precipitate from steps (1) and (2);

[0023] N1. The waste materials and precipitates in steps (1) and (2) are mixed uniformly by a ball mill, and then granulated by a granulator. The granulated mixed solid is sent to a rotary kiln for roasting;

[0024] N2, control the temperature of the rotary kiln to roast in the range of 1173-1273K, and convert lithium, potassium, cesium and rubidium in the waste into solid chlorides soluble in water. After being dissolved in water, crude lithium carbonate and other compound products are obtained through crystallization separation. The obtained crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate;

[0025] N3, control the temperature of the rotary kiln to roast in the range of 1273 ~ 1873K, the lithium, potassium, cesium and rubidium in the waste are converted into gaseous chlorides, and then the crude lithium carbonate and other compound products are extracted by collection and separation. The obtained crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate.

[0026] As a preferred embodiment of the process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to the present invention, in step S3, the drying conditions are 100° C. to 150° C., the drying time is 40 to 60 min, and the drying operation is a centrifugal drying operation.

[0027] As a preferred embodiment of the process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to the present invention, in step A2, stirring is performed while introducing carbon dioxide gas.

[0028] As a preferred embodiment of the process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to the present invention, wherein: in the step (1), in the first static sedimentation operation, the static sedimentation time is 2 h to 4 h, and in the second static sedimentation operation, the static sedimentation time is 4 h to 8 h.

[0029] As a preferred embodiment of the process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to the present invention, the volume of the lithium chloride ethanol solution in the step (1) is 70-80% of the volume of the sodium hydroxide ethanol solution, the dropping speed is 2-4 mL / min, the temperature of the ultrasonic dispersion is 30-50°C, the ultrasonic frequency is 40-80 kHz, the pressure of the vacuum distillation is 80-90 KPa of the atmospheric pressure, the temperature is 70-80°C, and the volume after the vacuum distillation is 20-30% of the volume of the suspended alcohol solution.

[0030] Compared with existing technologies:

[0031] 1. By adding barium carbonate, sulfate ions and calcium ions are removed at the same time, avoiding the multiple addition of impurity removers. The pH is subsequently adjusted to remove cations such as iron and magnesium, and then filtered together to avoid multiple filtrations. In addition, barium carbonate itself is a poorly soluble substance, and excess barium carbonate can be removed together during filtration, which is easy to control and avoids the introduction of other impurities. The obtained lithium chloride has high purity;

[0032] 2. The difference in solubility between lithium carbonate and sodium chloride is used to achieve rapid impurity removal of lithium carbonate to obtain lithium carbonate with higher purity. The solubility of lithium chloride and sodium hydroxide in ethanol, supplemented by the insolubility of sodium chloride and lithium carbonate in ethanol, can promote the reaction.

[0033] 3. Multiple preparation methods can be used simultaneously to reduce the impurities contained in the prepared lithium chloride and increase the purity of lithium chloride;

[0034] 4. The waste generated during the preparation process is roasted at two temperatures to remove impurities, obtain lithium carbonate and other compounds, and further extract the waste to increase resource utilization and reduce resource waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below in combination with the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0036] Figure 1 It is a step diagram of the preparation method of the present invention. DETAILED DESCRIPTION

[0037] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0038] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Secondly, the present invention is described in detail with reference to schematic diagrams. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0041] The present invention provides a process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate. Figure 1 , including the following steps:

[0042] 1) Extraction: Extract lithium chloride from organic reaction wastewater;

[0043] S1. placing organic wastewater in a reaction kettle, adding solid barium carbonate to the organic wastewater for stirring, heating the mixture to 60-70° C. during the stirring process, and performing a preliminary static precipitation operation after the heating reaction is completed to obtain a lithium-containing mixed solution;

[0044] S2, adding 30% liquid caustic soda to the lithium-containing mixed solution prepared in step S1 to make its pH reach 9-13, stirring and heating, and after the temperature reaches 95°C, evenly adding soda ash solution, the concentration of sodium carbonate in the soda ash solution is 200-260g / L, and maintaining the temperature of the reactor at 90-100°C during the addition process. After adding the soda ash solution, keep the temperature constant for 1-2 hours, and then perform a secondary static precipitation operation after the constant temperature;

[0045] S3, filtering the mixed solution obtained in step S2 to obtain a lithium chloride solution and a filter residue, evaporating and concentrating the lithium chloride solution to obtain a lithium chloride slurry, and drying the lithium chloride slurry to obtain industrial grade lithium chloride (drying conditions are 100° C. to 150° C., drying time is 40 to 60 min, and the drying operation adopts a centrifugal drying operation);

[0046] (In step 1), in the first static precipitation operation, the static precipitation time is 2h to 4h, and in the second static precipitation operation, the static precipitation time is 4h to 8h) (the volume of lithium chloride ethanol solution is 70-80% of the volume of sodium hydroxide ethanol solution, the dropping speed is 2-4mL / min, the temperature of ultrasonic dispersion is 30-50°C, the ultrasonic frequency is 40-80kHz, the pressure of vacuum distillation is 80-90KPa of atmospheric pressure, the temperature is 70-80°C, and the volume after vacuum distillation is 20-30% of the volume of the suspended alcohol solution);

[0047] 2) The first preparation method is to prepare lithium carbonate from the obtained industrial-grade lithium chloride:

[0048] A1. Add lithium chloride to anhydrous ethanol and stir at a constant temperature of 90-100°C until it is completely dissolved to obtain lithium chloride ethanol solution;

[0049] A2, adding sodium hydroxide ethanol solution to the lithium chloride ethanol solution prepared in A1, and introducing carbon dioxide gas at the same time, obtaining a suspended alcohol solution through ultrasonic reaction, and cooling and filtering after reduced pressure distillation reaction to obtain a mixed precipitate (in step A2, stirring operation is performed while introducing carbon dioxide gas);

[0050] A3. Heat distilled water and slowly add it to the mixed precipitate until the precipitate is continuously reduced to obtain a suspension, filter while hot to obtain lithium carbonate precipitate, wash with anhydrous ethanol several times and then dry to obtain lithium carbonate.

[0051] 3) The second preparation method is to prepare lithium carbonate from the obtained industrial-grade lithium chloride;

[0052] B1. Mix lithium chloride, sodium potassium sulfate mixed salt additive and calcium carbonate in a certain proportion through a ball mill, and then granulate them through a granulator. The granulated mixed solid is sent to a rotary kiln for roasting. After the roasted material is cooled, it is wet-milled in a ball mill.

[0053] B2, placing the raw material after wet grinding in step B1 into a leaching kettle, adding circulating water for heating and immersion, maintaining a constant temperature during the immersion process, and obtaining a lithium sulfate mother liquor;

[0054] B3, adding a neutralizing liquid auxiliary agent to the lithium sulfate mother liquor in B2 to neutralize and remove impurities, evaporating and concentrating, adding to a saturated sodium carbonate solution, and precipitating lithium to obtain a crude lithium carbonate product;

[0055] B4. The crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate.

[0056] 4) Waste preparation and extraction, further extracting the waste and sediment in steps 1) and 2);

[0057] N1. The waste materials and precipitates in steps 1) and 2) are mixed evenly by a ball mill, and then granulated by a granulator. The granulated mixed solids are sent to a rotary kiln for roasting;

[0058] N2, control the temperature of the rotary kiln to roast in the range of 1173-1273K, and convert lithium, potassium, cesium and rubidium in the waste into solid chlorides soluble in water. After being dissolved in water, crude lithium carbonate and other compound products are obtained through crystallization separation. The obtained crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate;

[0059] N3, control the temperature of the rotary kiln to roast in the range of 1273 ~ 1873K, the lithium, potassium, cesium and rubidium in the waste are converted into gaseous chlorides, and then the crude lithium carbonate and other compound products are extracted by collection and separation. The obtained crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate.

[0060] Although the present invention has been described above with reference to the embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, as long as there is no structural conflict, the various features in the embodiments disclosed in the present invention may be used in combination with each other in any manner, and the fact that these combinations are not exhaustively described in this specification is only for the sake of omitting space and saving resources. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate. It is characterized in that Includes the following steps: (1) Extraction: Extract lithium chloride from organic reaction wastewater; S1. placing organic wastewater in a reaction kettle, adding solid barium carbonate to the organic wastewater for stirring, heating the mixture to 60-70° C. during the stirring process, and performing a preliminary static precipitation operation after the heating reaction is completed to obtain a lithium-containing mixed solution; S2, adding 30% liquid caustic soda to the lithium-containing mixed solution prepared in step S1 to make its pH reach 9-13, stirring and heating, and after the temperature reaches 95°C, evenly adding soda ash solution, the concentration of sodium carbonate in the soda ash solution is 200-260g / L, and maintaining the temperature of the reactor at 90-100°C during the addition process. After adding the soda ash solution, keep the temperature constant for 1-2 hours, and then perform a secondary static precipitation operation after the constant temperature; S3, filtering the mixed solution obtained in step S2 to obtain a lithium chloride solution and a filter residue, evaporating and concentrating the lithium chloride solution to obtain a lithium chloride slurry, and drying the lithium chloride slurry to obtain industrial grade lithium chloride; (2) The first preparation method is to prepare lithium carbonate from the obtained industrial-grade lithium chloride, comprising steps A1-A3: A1. Add lithium chloride to anhydrous ethanol and stir at a constant temperature of 90-100°C until it is completely dissolved to obtain lithium chloride ethanol solution; A2, adding sodium hydroxide ethanol solution to the lithium chloride ethanol solution prepared in A1, and introducing carbon dioxide gas at the same time, obtaining a suspended alcohol solution through ultrasonic reaction, and cooling and filtering after vacuum distillation to obtain a mixed precipitate; A3, heating distilled water and slowly adding it to the mixed precipitate until the precipitate is continuously reduced to obtain a suspension, filtering while hot to obtain lithium carbonate precipitate, washing with anhydrous ethanol several times and drying to obtain lithium carbonate; (3) The second preparation method is to prepare lithium carbonate from the obtained industrial-grade lithium chloride, comprising steps B1-B4: B1, lithium chloride, sodium potassium sulfate mixed salt additive and calcium carbonate are mixed evenly in a certain proportion by a ball mill, and then granulated by a granulator, and the granulated mixed solid is sent to a rotary kiln for roasting, and the roasted material is wet-milled by a ball mill after cooling; B2, placing the raw material after wet grinding in step B1 into a leaching kettle, adding circulating water for heating and immersion, maintaining a constant temperature during the immersion process, and obtaining a lithium sulfate mother liquor; B3, adding a neutralizing liquid auxiliary agent to the lithium sulfate mother liquor in B2 to neutralize and remove impurities, evaporating and concentrating, adding to a saturated sodium carbonate solution, and precipitating lithium to obtain a crude lithium carbonate product; B4, the crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate; (4) Waste preparation and extraction, further extracting the waste and precipitate in steps (1) and (2), including steps N1-N3: N1. The waste materials and precipitates in steps (1) and (2) are mixed uniformly by a ball mill, and then granulated by a granulator. The granulated mixed solid is sent to a rotary kiln for roasting; N2, control the temperature of the rotary kiln to roast in the range of 1173-1273K, and convert lithium, potassium, cesium and rubidium in the waste into solid chlorides soluble in water. After being dissolved in water, crude lithium carbonate and other compound products are obtained through crystallization separation. The obtained crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate; N3, control the temperature of the rotary kiln to roast in the range of 1273 ~ 1873K, the lithium, potassium, cesium and rubidium in the waste are converted into gaseous chlorides, and then the crude lithium carbonate and other compound products are extracted by collection and separation. The obtained crude lithium carbonate is washed with anhydrous ethanol several times, dried and crushed to obtain battery-grade lithium carbonate.

2. The process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to claim 1, It is characterized in that In step S3, the drying condition is 100° C. to 150° C., the drying time is 40 to 60 minutes, and the drying operation is a centrifugal drying operation.

3. The process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to claim 1, It is characterized in that In the step A2, stirring is performed while introducing carbon dioxide gas.

4. The process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to claim 1, It is characterized in that In the step (1), in the first static sedimentation operation, the static sedimentation time is 2 hours to 4 hours, and in the second static sedimentation operation, the static sedimentation time is 4 hours to 8 hours.

5. The process for recovering lithium chloride from organic reaction wastewater to prepare battery-grade lithium carbonate according to claim 1, It is characterized in that In the step (1), the volume of the lithium chloride ethanol solution is 70-80% of the volume of the sodium hydroxide ethanol solution, the dropping speed is 2-4 mL / min, the temperature of the ultrasonic dispersion is 30-50° C., the ultrasonic frequency is 40-80 kHz, the pressure of the vacuum distillation is 80-90 KPa of the atmospheric pressure, the temperature is 70-80° C., and the volume after the vacuum distillation is 20-30% of the volume of the suspended alcohol solution.

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