A method and device for purifying lithium chloride containing organic matter

Abstract

The present invention belongs to the technical field of lithium chloride purification, and specifically relates to a method and a device for purifying lithium chloride containing organic matter. The method for purifying lithium chloride containing organic matter comprises the following steps: calcining the organic lithium chloride raw material under an oxygen-containing atmosphere, dissolving the obtained sintered product in a dissolving solution, filtering to obtain a purified solution, then subjecting it to N-level precipitation filtration cold box treatment, recovering the obtained filtrate as a dissolving solution for recycling, and drying the obtained solid to obtain a lithium chloride product; the dissolving solution comprises an organic solvent I and an organic solvent II, the organic solvent I is selected from at least one of pyrrolidone solvents, amide solvents, lactam solvents, and piperidone solvents, and the organic solvent II is selected from urea solvents and / or alcohol solvents. The purification method provided by the present invention obtains a high-purity lithium chloride product through the mutual cooperation of various processing steps, and the yield is high, and the recovered solvent has a low impurity content and can be recycled for a long time.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium chloride purification, and in particular relates to a method and a device for purifying lithium chloride containing organic matter. Background Art

[0002] Lithium chloride (LiCl) is a white crystal and an important inorganic compound widely used in battery manufacturing, organic synthesis, metal smelting and recycling, refrigeration equipment, new energy and other fields. Among them, lithium chloride plays an important role in the electric vehicle (EV) industry.

[0003] In recent years, with the continuous development of battery material industry technology, the consumption of lithium chloride has been increasing, and more and more companies are paying more and more attention to the recycling of lithium chloride. The recycling methods of lithium chloride mainly include: conversion method, solvent extraction method, electrochemical recovery method, thermal concentration crystallization method, cooling crystallization method, etc. At present, the prior art commonly uses a combination of solvent extraction + cooling crystallization to purify lithium chloride. The process flow of this method is relatively simple, and the organic solvent can be recycled. However, when purifying organic lithium chloride, this method will cause organic impurities in the organic solvent to accumulate continuously, which will affect the purity and yield of the purified lithium chloride product when used in a long-term cycle. Therefore, for the purification of organic lithium chloride, it is urgent to find a purification method with high yield, high purity and long-term recycling of solvents. Summary of the invention

[0004] One of the purposes of the present invention is to provide a method for purifying lithium chloride containing organic matter, in view of the problem that in the prior art, when purifying lithium chloride containing organic matter and other impurities, organic impurities in the organic solvent are continuously accumulated during long-term recycling, resulting in a decrease in the purity and yield of the purified lithium chloride product. The method not only improves the purity and yield of the lithium chloride product, but also reduces the possible impurity content of the organic solvent, thereby improving the recycling rate.

[0005] Specifically, the method for purifying lithium chloride containing organic matter comprises the following steps: calcining a lithium chloride raw material containing organic matter in an oxygen-containing atmosphere, dissolving the obtained sintered product in a dissolving solution, filtering the obtained sintered product to obtain a purified solution, subjecting the purified solution to a precipitation filtration treatment in an N-level precipitation filtration cold box, N≧2, recovering the obtained filtrate as a dissolving solution for recycling, and drying the obtained solid to obtain a lithium chloride product; the dissolving solution comprises an organic solvent I and an organic solvent II, wherein the organic solvent I is selected from at least one of pyrrolidone solvents, amide solvents, lactam solvents, and piperidone solvents, and the organic solvent II is selected from urea solvents and / or alcohol solvents.

[0006] In a preferred embodiment, the calcination treatment conditions include: a temperature of 400 to 500° C. and a time of 2 to 4 hours.

[0007] In a preferred embodiment, the cooling rate of the calcination treatment is 10 to 20° C. / h.

[0008] In a preferred embodiment, the mass ratio of the sintered product to the dissolved liquid is (10-15):100.

[0009] In a preferred embodiment, the mass ratio of the organic solvent I to the organic solvent II is (50-90):10.

[0010] In a preferred embodiment, the organic solvent I is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dipropylacetamide, N,N-dimethylbenzamide, caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-propylcaprolactam, N-butylcaprolactam, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-3-pyrrolidone, N-ethyl-3-pyrrolidone, N-methyl-2-piperidone, N-ethyl-4-piperidone, 1-isopropyl-4-piperidone, and 1-ethyl-3-methyl-4-piperidone.

[0011] In a preferred embodiment, the organic solvent II is at least one selected from tetramethyl urea, N,N'-dimethylethylene urea, N,N'-dimethylpropylene urea, methanol, ethanol, and isopropanol.

[0012] In a preferred embodiment, the conditions for dissolving the sintered product in the dissolving solution include: a temperature of 60 to 80°C.

[0013] In a preferred embodiment, the temperature of the N-stage precipitation filtration cold box is -15 to 0°C.

[0014] In a preferred embodiment, the purified solution includes a pre-cooling treatment before the N-stage precipitation and filtration treatment, the purpose of which is to adjust the temperature of the purified solution to 0-30°C.

[0015] The second object of the present invention is to provide a lithium chloride purification device containing organic matter, the purification device comprising:

[0016] A calcining furnace, used for calcining the lithium chloride raw material containing organic matter to obtain a sintered product;

[0017] A dissolving tank, used for dissolving the sintered product in a dissolving solution to obtain a mixed solution;

[0018] A filter, used for filtering and removing insoluble solids in the mixed solution to obtain a purified solution;

[0019] A multi-stage precipitation filtration cold box, used for subjecting the purified solution to precipitation filtration treatment to obtain a filtrate and a solid precipitate, wherein the inlet of the multi-stage precipitation filtration cold box is connected to the outlet of the filter;

[0020] A drying box, used to dry the solid precipitate to obtain a lithium chloride product;

[0021] The solvent recovery tank is used to store the recovered solution for recycling. The inlet of the solvent recovery tank is connected to the filtrate outlet of the multi-stage precipitation filtration cold box, and the outlet is connected to the inlet of the dissolution tank.

[0022] In a preferred embodiment, the dissolving tank is provided with a heater for heating the dissolving liquid to dissolve the sintered product.

[0023] In a preferred embodiment, the temperature of the dissolving solution is 60-80°C.

[0024] In a preferred embodiment, the filter pore size of the filter is 20-50 nm.

[0025] In a preferred embodiment, a precooler is provided on the pipeline connecting the inlet of the multi-stage precipitation filtration cold box and the outlet of the filter for initially cooling the purified solution.

[0026] In a preferred embodiment, the operating temperature of the precooler is 0-30°C.

[0027] In a preferred embodiment, the operating temperature of the multi-stage sedimentation filtration cold box is -15 to 0°C.

[0028] In a preferred embodiment, the filtration pore size of the multi-stage sedimentation filtration cold box is 100-500 nm.

[0029] In a preferred embodiment, the steam outlet of the drying box is connected to the inlet of the solvent recovery tank, and a condenser is provided on the pipeline connecting the two.

[0030] Beneficial effects:

[0031] For lithium chloride raw materials containing organic matter and other impurities such as metals, in the purification method provided by the present invention, the lithium chloride raw material is first calcined in an air atmosphere to remove organic matter and oxidize other impurities such as metals into insoluble oxides, and then the obtained sintered product is dissolved in a specific dissolving solution, and the undissolved substances are removed by filtration to obtain a purified solution, and then the lithium chloride in the purified solution is precipitated and separated by N-level precipitation filtration cold box treatment, and the filtrate can be recycled as a dissolving solution, and the separated solid precipitate is dried to obtain a lithium chloride product. In summary, the purification method provided by the present invention gradually removes organic matter and other impurities such as metals in the raw material through the mutual cooperation of various processing steps, thereby obtaining a lithium chloride product with high purity, and the yield of lithium chloride is high, and the recovered solvent has a low impurity content and can be recycled for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of the organic-containing lithium chloride purification device provided in Example 1 of the present invention.

[0033] Figure 2 It is a schematic structural diagram of a multi-stage precipitation filtration cold box of a lithium chloride purification device containing organic matter provided in Example 1 of the present invention. DETAILED DESCRIPTION

[0034] The method for purifying organic-containing lithium chloride provided by the present invention comprises the following steps: calcining an organic-containing lithium chloride raw material under an oxygen-containing atmosphere, dissolving the obtained sintered product in a dissolving solution, filtering the obtained product to obtain a purified solution, subjecting the purified solution to a precipitation filtering treatment in an N-level precipitation filtering cold box, N≧2, recycling the obtained filtrate as a dissolving solution for recycling, and drying the obtained solid to obtain a lithium chloride product; the dissolving solution comprises an organic solvent I and an organic solvent II, wherein the organic solvent I is selected from at least one of pyrrolidone solvents, amide solvents, lactam solvents, and piperidone solvents, and the organic solvent II is selected from urea solvents and / or alcohol solvents.

[0035] In the present invention, the conditions for the calcination treatment may include: the temperature is preferably 400-500°C, such as 400°C, 420°C, 450°C, 480°C, 500°C or any value therebetween, which is more conducive to ensuring that organic matter is oxidized and removed and other impurities such as metals are oxidized into insoluble oxides, and lithium chloride will not be converted into other substances; the time is preferably 2-4h, such as 2h, 2.5h, 3h, 3.5h, 4h or any value therebetween.

[0036] Furthermore, the cooling rate of the calcination treatment is preferably 10-20°C / h, such as 10°C / h, 12°C / h, 15°C / h, 18°C / h, 20°C / h or any value therebetween.

[0037] Furthermore, when the organic-containing lithium chloride raw material is calcined, the layer thickness of the raw material is preferably within 25 mm, such as 25 mm, 20 mm, 15 mm, 10 mm, 5 mm, etc., which is beneficial to ensure that the organic-containing lithium chloride raw material is fully in contact with the air during the calcination process, thereby improving the oxidation efficiency of organic matter and other impurities such as metals.

[0038] Furthermore, the oxygen-containing atmosphere may be an air atmosphere, or a mixed gas atmosphere of oxygen and other inert gases, preferably an air atmosphere.

[0039] Furthermore, the air flow rate during the calcination treatment is preferably 5 to 10 L / min, such as 5 L / min, 6 L / min, 7 L / min, 8 L / min, 9 L / min, 10 L / min or any value therebetween.

[0040] In the present invention, the mass ratio of the sintered product to the dissolved liquid is preferably (10-15):100, such as 10:100, 11:100, 12:100, 13:100, 14:100, 15:100 or any value therebetween.

[0041] In the present invention, the mass ratio of the organic solvent I to the organic solvent II is preferably (50-90):10, such as 50:10, 60:10, 70:10, 80:10, 90:10 or any value therebetween. This is more conducive to ensuring that the lithium chloride in the sintered product can be fully dissolved and fully precipitated in the subsequent process, thereby facilitating the improvement of the yield of lithium chloride.

[0042] Further, specific examples of the pyrrolidone solvent include, but are not limited to, at least one of N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, 1-propyl-2-pyrrolidone (CAS 3470-99-3), 1-butyl-2-pyrrolidone (CAS 3470-98-2), N-cyclohexyl-2-pyrrolidone, N-methyl-3-pyrrolidone (CAS 68165-06-0), and N-ethyl-3-pyrrolidone (CAS102153-86-6). Specific examples of the amide solvent include, but are not limited to, at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dipropylacetamide, and N,N-dimethylbenzamide. Specific examples of the lactam solvent include, but are not limited to, at least one of caprolactam, N-methyl caprolactam, N-ethyl caprolactam, N-propyl caprolactam (CAS 52644-85-6), and N-butyl caprolactam. Specific examples of the piperidone solvent include, but are not limited to, at least one of N-methyl-2-piperidone (CAS 931-20-4), N-ethyl-4-piperidone (CAS 3612-18-8), 1-isopropyl-4-piperidone (CAS 5355-68-0), and 1-ethyl-3-methyl-4-piperidone (3612-16-6).

[0043] Further, specific examples of the urea solvent include, but are not limited to, at least one of tetramethyl urea, N,N'-dimethylethylene urea, and N,N'-dimethylpropylene urea. Specific examples of the alcohol solvent include, but are not limited to, at least one of methanol, ethanol, and isopropanol.

[0044] In the present invention, the conditions for dissolving the sintered product in the dissolving solution may include: the temperature is preferably 60-80°C, such as 60°C, 65°C, 70°C, 75°C, 80°C or any value therebetween, which is more conducive to fully dissolving the lithium chloride in the sintered product in the dissolving solution, thereby removing the insoluble matter in the sintered product by filtration, and further improving the yield and purity of lithium chloride. The stirring speed may also be 80-120rpm, such as 80rpm, 90rpm, 100rpm, 110rpm, 120rpm or any value therebetween.

[0045] In the present invention, the temperature of the N-stage precipitation filtration cold box is preferably -15 to 0°C, such as -15°C, -12°C, -10°C, -8°C, -5°C, -2°C, 0°C or any value therebetween.

[0046] In the present invention, the purified solution includes a pre-cooling treatment before the N-stage precipitation filtration treatment, the purpose of which is to adjust the temperature of the purified solution to preferably 0-30°C, such as 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C or any value therebetween.

[0047] In the present invention, the temperature of the drying treatment is preferably 200-250°C, such as 200°C, 210°C, 220°C, 230°C, 240°C, 250°C or any value therebetween. The time of the drying treatment can be selected according to actual conditions. When the lithium chloride solid precipitate is dried, the layer thickness of the paving material is preferably within 20 mm, such as 20 mm, 15 mm, 10 mm, 5 mm, etc.

[0048] In the present invention, the filtration treatment is preferably carried out in a filter, and the filtration pore size is preferably 20 to 50 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm or any value therebetween.

[0049] In the present invention, the filtration pore size of the N-stage precipitation filtration cold box is preferably 100-500 nm, such as 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or any value therebetween. The filtration pore size of each stage of the precipitation filtration cold box can be the same or different.

[0050] The organic-containing lithium chloride purification device provided by the present invention comprises:

[0051] A calcining furnace, used for calcining the lithium chloride raw material containing organic matter to obtain a sintered product;

[0052] A dissolving tank, used for dissolving the sintered product in a dissolving solution to obtain a mixed solution;

[0053] A filter, used for filtering and removing insoluble solids in the mixed solution to obtain a purified solution;

[0054] A multi-stage precipitation filtration cold box, used for subjecting the purified solution to precipitation filtration treatment to obtain a filtrate and a solid precipitate, wherein the inlet of the multi-stage precipitation filtration cold box is connected to the outlet of the filter;

[0055] A drying box, used to dry the solid precipitate to obtain a lithium chloride product;

[0056] The solvent recovery tank is used to store the recovered solution for recycling. The inlet of the solvent recovery tank is connected to the filtrate outlet of the multi-stage precipitation filtration cold box, and the outlet is connected to the inlet of the dissolution tank.

[0057] Furthermore, the calcining furnace can be any type of existing calcining furnaces, such as a rotary hearth type, a belt type, a kiln type, etc., preferably a rotary hearth type calcining furnace.

[0058] In the present invention, the shape and size of the dissolving tank are not specifically limited and can be selected according to actual processing needs. The dissolving tank is provided with a heater for heating the dissolving liquid to dissolve the sintered product.

[0059] Furthermore, the temperature of the dissolving solution is preferably 60-80°C, such as 60°C, 65°C, 70°C, 75°C, 80°C or any value therebetween.

[0060] In the present invention, the filtration pore size of the filter is preferably 20-50 nm, such as 20 nm, 25 nm, 30 nm, 35 nm, 40 nm, 45 nm, 50 nm or any value therebetween.

[0061] In the present invention, the multi-stage sedimentation filtration cold box is provided with N filter bags, N≧2, the inlet of the first filter bag is connected to the outlet of the filter and the filtrate outlet is connected to the inlet of the next filter bag, and the filtrate outlet of the last filter bag is connected to the inlet of the solvent recovery tank. The N filter bags are preferably installed in a detachable manner so that the solid precipitates intercepted by the filter bags can be collected and transferred to the drying box for subsequent treatment.

[0062] Furthermore, the filtration pore sizes of the N filter bags are preferably 100-500 nm, such as 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm or any value therebetween. The filtration pore sizes of the N filter bags may be the same or different, and may decrease step by step along the proceeding direction.

[0063] Furthermore, the operating temperature of the multi-stage precipitation filtration cold box is preferably -15 to 0°C, such as -15°C, -12°C, -10°C, -8°C, -5°C, -2°C, 0°C or any value therebetween.

[0064] In the present invention, a precooler is provided on the pipeline connecting the inlet of the multi-stage precipitation filtration cold box and the outlet of the filter, for initially cooling the purified solution.

[0065] Furthermore, the operating temperature of the precooler is preferably 0-30°C, such as 0°C, 5°C, 10°C, 15°C, 20°C, 25°C, 30°C or any value therebetween.

[0066] In the present invention, the steam outlet of the drying box is connected to the inlet of the solvent recovery tank, and a condenser is provided on the pipeline connecting the two.

[0067] Furthermore, the drying box is provided with at least one partition for spreading the lithium chloride solid precipitate, and the spreading thickness is preferably within 20 mm, such as 20 mm, 15 mm, 10 mm, 5 mm, etc.

[0068] Furthermore, the operating temperature of the drying box is preferably 200-250°C, such as 200°C, 210°C, 220°C, 230°C, 240°C, 250°C or any value therebetween.

[0069] The present invention will be described in detail below through specific embodiments.

[0070] Example 1

[0071] This embodiment is used to illustrate a device and method for purifying lithium chloride containing organic matter.

[0072] Reference Figure 1 and Figure 2 The organic-containing lithium chloride purification device provided in this embodiment specifically includes: a rotary hearth calcining furnace, a dissolving tank, a filter, a precooler, a four-stage precipitation and filtration cold box, a drying box, and a solvent recovery tank.

[0073] The rotary hearth calcining furnace is used to calcine the organic lithium chloride raw material to obtain a sintered product. The dissolving tank is used to dissolve the sintered product in the dissolving liquid to obtain a mixed solution, and is provided with a stirrer I and a heater. The filter is used to filter and remove the insoluble solids in the mixed solution to obtain a purified solution, and the filter aperture is 35nm. The outlet of the dissolving tank is connected to the inlet of the filter, and a centrifugal pump I is provided on the connecting pipeline between the two. The solution outlet of the filter is connected to the inlet of the precooler, and the outlet of the precooler is connected to the inlet of the four-stage precipitation filter cold box, and a stirrer II is provided in the precooler. The four-stage precipitation filter cold box is used to precipitate and filter the purified solution to obtain a filtrate and a solid precipitate, and is provided with four detachable filter bags, and the filter aperture of the filter bags is 300nm. The drying box is used to dry the solid precipitate to obtain a lithium chloride product, and the steam outlet of the drying box is connected to the inlet of the solvent recovery tank, and a condenser is provided on the connecting pipeline between the two. The solvent recovery tank is used to store the filtrate of the four-stage sedimentation filtration cold box and the condensate of the condenser so as to be recycled as a dissolving liquid. The inlet of the solvent recovery tank is connected with the filtrate outlet of the four-stage sedimentation filtration cold box and a centrifugal pump II is arranged on the connecting pipeline between the two. The outlet of the solvent recovery tank is connected with the inlet of the dissolving tank and a centrifugal pump III is arranged on the connecting pipeline between the two.

[0074] The method for purifying organic-containing lithium chloride provided in this embodiment is carried out in the purification device provided above, and the specific steps are as follows:

[0075] 200 kg of lithium chloride containing impurities was placed in a rotary hearth calcining furnace, the layer thickness of the raw material was 20 mm, and 6 L / min of compressed air was continuously introduced. The heating temperature of the calcining furnace was controlled at 420 ° C and kept at a constant temperature for 3 hours, then cooled to 30 ° C at 15 ° C / h, and the introduction of air was stopped to obtain 122 kg of sintered solid;

[0076] 122 kg of sintered solid was placed in a dissolving tank, 1000 kg of dissolving solution (N-methyl-2-pyrrolidone and isopropanol in a ratio of 90:10) was added, heated to 70° C., and stirred until dissolved to obtain a mixed solution;

[0077] The mixed solution is transported to the filter through centrifugal pump I for filtration to obtain a purified solution. The filter has a filtration pore size of 35nm. The purified solution is cooled to 15°C in a precooler, and then enters a four-stage precipitation filtration cold box to be cooled to -10°C and solid-liquid separation is performed. The filtration pore size of the four filter bags is 300nm. The filtrate is transported to a solvent recovery tank through centrifugal pump II, and the solid precipitate enters a drying box and is dried at 220°C for 2h. The layer thickness of the material is 10mm. 103kg of lithium chloride product is obtained and sealed and packaged.

[0078] Example 2

[0079] The organic-containing lithium chloride purification device provided in this embodiment is the same as the purification device provided in Example 1, except that the pore size of the filter is 20 nm, the filtration pore size of the filter bag is 150 nm, and the rest of the structures are the same.

[0080] The method for purifying organic-containing lithium chloride provided in this embodiment is carried out in the purification device provided above, and the specific steps are as follows:

[0081] 200 kg of lithium chloride containing impurities was placed in a rotary hearth calcining furnace, the layer thickness of the raw material was 20 mm, and 6 L / min of compressed air was continuously introduced. The heating temperature of the calcining furnace was controlled at 450 ° C and kept at a constant temperature for 3 hours, then cooled to 30 ° C at 10 ° C / h, and the introduction of air was stopped to obtain 118 kg of sintered solid;

[0082] 118 kg of sintered solid was placed in a dissolving tank, 1000 kg of dissolving solution (N-methyl-2-pyrrolidone and isopropanol in a ratio of 75:10) was added, heated to 80° C., and stirred until dissolved to obtain a mixed solution;

[0083] The mixed solution is transported to the filter through centrifugal pump I for filtration to obtain a purified solution. The filter pore size is 20nm. The purified solution is cooled to 0°C in a precooler, and then enters a four-stage precipitation filtration cold box to be cooled to -15°C and solid-liquid separation is performed. The filtration pore size of the four filter bags is 150nm. The filtrate is transported to a solvent recovery tank through centrifugal pump II. The solid precipitate enters a drying box and is dried at 220°C for 3 hours. The layer thickness of the material is 10mm. 100kg of lithium chloride product is obtained and sealed and packaged.

[0084] Example 3

[0085] The organic-containing lithium chloride purification device provided in this embodiment is the same as the purification device provided in Example 1, except that the pore size of the filter is 50 nm and the filter pore size of the filter bag is 450 nm, and the rest of the structures are the same.

[0086] The method for purifying organic-containing lithium chloride provided in this embodiment is carried out in the purification device provided above, and the specific steps are as follows:

[0087] 200 kg of lithium chloride containing impurities was placed in a rotary hearth calcining furnace, the layer thickness of the raw material was 20 mm, and 6 L / min of compressed air was continuously introduced. The heating temperature of the calcining furnace was controlled at 480 ° C and kept at a constant temperature for 3 hours, then cooled to 30 ° C at 20 ° C / h, and the introduction of air was stopped to obtain 116 kg of sintered solid;

[0088] 116 kg of sintered solid was placed in a dissolving tank, 1000 kg of dissolving solution (N-methyl-2-pyrrolidone and isopropanol in a ratio of 50:10) was added, heated to 60° C., and stirred until dissolved to obtain a mixed solution;

[0089] The mixed solution is transported to the filter through centrifugal pump I for filtration to obtain a purified solution. The filter has a filtration pore size of 50nm. The purified solution is cooled to 30°C in a precooler, and then enters a four-stage precipitation filtration cold box to be cooled to -5°C and solid-liquid separation is performed. The filtration pore size of the four filter bags is 450nm. The filtrate is transported to a solvent recovery tank through centrifugal pump II, and the solid precipitate enters a drying box and is dried at 220°C for 2.5h. The layer thickness of the material is 10mm. 98kg of lithium chloride product is obtained and sealed and packaged.

[0090] Example 4

[0091] This embodiment uses the purification device provided in Example 1 to purify lithium chloride containing organic matter. The specific steps are the same as the purification method provided in Example 1. The difference is that the dissolving solution used is obtained by mixing N-methylcaprolactam and tetramethylurea in a mass ratio of 90:10, and the other conditions are the same as in Example 1, thereby obtaining 102 kg of lithium chloride product and sealing it.

[0092] Comparative Example 1

[0093] This comparative example provides a method for purifying lithium chloride containing organic matter. The specific steps are the same as the purification method provided in Example 1, except that 200 kg of impure lithium chloride is not calcined but directly dissolved in a dissolution tank. The other conditions are the same as those in Example 1, thereby obtaining 100 kg of lithium chloride product and sealing it.

[0094] Comparative Example 2

[0095] This comparative example provides a method for purifying lithium chloride containing organic matter. The specific steps are the same as the purification method provided in Example 1, except that 1000 kg of N-methyl-2-pyrrolidone is used as the dissolving liquid, and the other conditions are the same as those in Example 1, thereby obtaining 96 kg of lithium chloride product and sealing it.

[0096] Comparative Example 3

[0097] This comparative example provides a method for purifying lithium chloride containing organic matter. The specific steps are the same as the purification method provided in Example 1, except that 1000 kg of isopropanol is used as the dissolving liquid, and the other conditions are the same as those in Example 1, thereby obtaining 95 kg of lithium chloride product and sealing it.

[0098] Comparative Example 4

[0099] This comparative example provides a method for purifying lithium chloride containing organic matter. The specific steps are the same as the purification method provided in Example 1, except that 6 L / min of nitrogen is introduced into the rotary hearth calcining furnace, and the other conditions are the same as in Example 1, thereby obtaining 101 kg of lithium chloride product and sealing it.

[0100] Test Case

[0101] The purity and various impurity contents of the lithium chloride products prepared in the examples and comparative examples were tested according to the methods of parts 3 to 7 and parts 9 and 11 of GB / T 11064-2013, wherein the organic matter content was tested using a total organic carbon (TOC) analyzer, and the results are shown in Table 1.

[0102] Table 1

[0103]

[0104] As can be seen from the results of Table 1, compared with Comparative Examples 1 to 4, the lithium chloride products obtained by the methods provided in Examples 1 to 4 of the present invention have better lithium chloride purity and yield. As can be seen from the comparison results of Example 1 with Comparative Examples 1 and Comparative Example 4, if the impurity-containing lithium chloride is not calcined or calcined under oxygen-containing conditions, the purity and yield of the obtained lithium chloride product are significantly reduced. As can be seen from the comparison results of Example 1 with Comparative Examples 2 and Comparative Examples 3, or only one of N-methyl-2-pyrrolidone and isopropanol is used as the dissolving liquid, the purity of the obtained lithium chloride product is slightly reduced, and the yield is also reduced.

[0105] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and intent of the present invention.

Claims

1. A method for purifying lithium chloride containing organic matter, characterized in that: The method for purifying organic-containing lithium chloride comprises the following steps: calcining an organic-containing lithium chloride raw material in an oxygen-containing atmosphere, dissolving the obtained sintered product in a dissolving solution, filtering the obtained product to obtain a purified solution, subjecting the purified solution to a precipitation filtration cold box of N levels, N≧2, recovering the obtained filtrate as a dissolving solution for recycling, and drying the obtained solid to obtain a lithium chloride product; the dissolving solution comprises an organic solvent I and an organic solvent II, wherein the organic solvent I is selected from at least one of pyrrolidone solvents, amide solvents, lactam solvents, and piperidone solvents, and the organic solvent II is selected from urea solvents and / or alcohol solvents.

2. The method for purifying organic-containing lithium chloride according to claim 1, characterized in that: The calcination treatment conditions include: temperature of 400-500°C and time of 2-4h; Preferably, the cooling rate of the calcination treatment is 10 to 20° C. / h.

3. The method for purifying organic-containing lithium chloride according to claim 1, characterized in that: The mass ratio of the sintered product to the dissolved liquid is (10-15):100; Preferably, the mass ratio of the organic solvent I to the organic solvent II is (50-90):

10.

4. The method for purifying organic-containing lithium chloride according to claim 1, characterized in that: The organic solvent I is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N,N-diethylacetamide, N,N-dipropylacetamide, N,N-dimethylbenzamide, caprolactam, N-methylcaprolactam, N-ethylcaprolactam, N-propylcaprolactam, N-butylcaprolactam, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-isopropyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, N-methyl-3-pyrrolidone, N-ethyl-3-pyrrolidone, N-methyl-2-piperidone, N-ethyl-4-piperidone, 1-isopropyl-4-piperidone and 1-ethyl-3-methyl-4-piperidone; Preferably, the organic solvent II is selected from at least one of tetramethyl urea, N,N'-dimethylethylene urea, N,N'-dimethylpropylene urea, methanol, ethanol and isopropanol.

5. The method for purifying organic-containing lithium chloride according to claim 1, characterized in that: The conditions for dissolving the sintered product in the dissolving solution include: a temperature of 60 to 80°C.

6. The method for purifying organic-containing lithium chloride according to claim 1, characterized in that: The temperature of the N-stage precipitation filtration cold box is -15 to 0°C; Preferably, the purified solution includes a pre-cooling treatment before the N-stage precipitation and filtration treatment, the purpose of which is to adjust the temperature of the purified solution to 0-30°C.

7. A lithium chloride purification device containing organic matter, characterized in that: The purification device comprises: A calcining furnace, used for calcining the lithium chloride raw material containing organic matter to obtain a sintered product; A dissolving tank, used for dissolving the sintered product in a dissolving solution to obtain a mixed solution; A filter, used for filtering and removing insoluble solids in the mixed solution to obtain a purified solution; A multi-stage precipitation filtration cold box, used for subjecting the purified solution to precipitation filtration treatment to obtain a filtrate and a solid precipitate, wherein the inlet of the multi-stage precipitation filtration cold box is connected to the outlet of the filter; A drying box, used to dry the solid precipitate to obtain a lithium chloride product; The solvent recovery tank is used to store the recovered solution for recycling. The inlet of the solvent recovery tank is connected to the filtrate outlet of the multi-stage precipitation filtration cold box, and the outlet is connected to the inlet of the dissolution tank.

8. The organic-containing lithium chloride purification device according to claim 7, characterized in that: The dissolving tank is provided with a heater for heating the dissolving liquid to dissolve the sintered product; Preferably, the temperature of the dissolving solution is 60-80°C; Preferably, the filter pore size of the filter is 20-50 nm.

9. The organic-containing lithium chloride purification device according to claim 7, characterized in that: A precooler is provided on the pipeline connecting the inlet of the multi-stage precipitation filtration cold box and the outlet of the filter, for initially cooling the purified solution; Preferably, the operating temperature of the precooler is 0 to 30°C; Preferably, the operating temperature of the multi-stage precipitation filtration cold box is -15 to 0°C; Preferably, the filtration pore size of the multi-stage sedimentation filtration cold box is 100-500 nm.

10. The organic-containing lithium chloride purification device according to claim 7, characterized in that: The steam outlet of the drying box is communicated with the inlet of the solvent recovery tank, and a condenser is arranged on the pipeline communicating therebetween.

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