WO2019100673A1 - Method for selective nitric acid leaching of lithium elements in aluminum electrolyte - Google Patents

Method for selective nitric acid leaching of lithium elements in aluminum electrolyte Download PDF

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Publication number
WO2019100673A1
WO2019100673A1 PCT/CN2018/087340 CN2018087340W WO2019100673A1 WO 2019100673 A1 WO2019100673 A1 WO 2019100673A1 CN 2018087340 W CN2018087340 W CN 2018087340W WO 2019100673 A1 WO2019100673 A1 WO 2019100673A1
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electrolyte
aluminum
lithium
aluminum electrolyte
leaching
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PCT/CN2018/087340
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French (fr)
Chinese (zh)
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王兆文
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东北大学
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/10—Obtaining alkali metals
    • C22B26/12—Obtaining lithium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F7/00—Compounds of aluminium
    • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
    • C01F7/46—Purification of aluminium oxide, aluminium hydroxide or aluminates
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B3/00—Extraction of metal compounds from ores or concentrates by wet processes
    • C22B3/04—Extraction of metal compounds from ores or concentrates by wet processes by leaching
    • C22B3/06—Extraction of metal compounds from ores or concentrates by wet processes by leaching in inorganic acid solutions, e.g. with acids generated in situ; in inorganic salt solutions other than ammonium salt solutions
    • C22B3/065—Nitric acids or salts thereof
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C3/00—Electrolytic production, recovery or refining of metals by electrolysis of melts
    • C25C3/06—Electrolytic production, recovery or refining of metals by electrolysis of melts of aluminium
    • C25C3/18—Electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention relates to the technical field of aluminum electrolyte extraction and recovery, and relates to a method for selectively leaching lithium element in an aluminum electrolyte by using nitric acid.
  • the lithium salt is greatly enriched in the electrolyte, reducing the initial crystal temperature of the electrolyte and the solubility of the alumina, causing the temperature of the aluminum electrolysis to decrease.
  • the increase in furnace bottom sedimentation, the decrease of current efficiency and the increase of energy consumption per ton of aluminum directly affect the economic benefits of China's aluminum electrolysis industry, which is an urgent problem to be solved in China's aluminum electrolysis industry. Therefore, the removal of lithium in the aluminum electrolyte is of great significance to the development of China's aluminum electrolysis industry.
  • lithium salt continues to expand, such as lithium batteries, aluminum-lithium alloys, lithium bromide air conditioners, atomic energy industry, organic synthesis, etc.
  • the demand for lithium salt is rapidly developing, and lithium resources are also facing challenges.
  • the aluminum-containing electrolyte can be used as a lithium salt resource, the lithium salt extracted from it is also of great significance to the development of the lithium salt industry in China.
  • the lithium salt in the aluminum electrolyte can be leached by using a nitric acid solution, but this immersion method not only leaches out the lithium salt, but also leaches all the components in the aluminum electrolyte, thus not only increasing the acid consumption, Moreover, the subsequent separation of the lithium salt from other components is difficult, resulting in a substantial increase in production costs.
  • the present invention provides a method for selectively leaching lithium elements in an aluminum electrolyte, which is capable of efficiently extracting lithium ions in an electrolyte, recovering high value-added lithium salts, and obtaining high purity at the same time.
  • the industrial electrolyte produced by aluminum electrolyte reduces the energy consumption and extraction cost of electrolytic aluminum production.
  • the invention provides a method for selective nitric acid leaching of lithium element in an aluminum electrolyte, comprising the following steps:
  • step S3 adding the aluminum electrolyte treated in step S1 to the acid solution obtained in step S2, stirring and heating to carry out leaching, in the leaching process, the reaction temperature is 20-85 ° C, the amount of aluminum electrolyte added according to the fluoride ion concentration in the solution And comprehensive control of acidity, wherein the acidity is pH less than 4, and the fluoride ion concentration is greater than 1 g/L;
  • the mixed solution after the reaction is filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction;
  • the primary filtrate is used for extracting lithium element, and the primary filter is washed, dried, returned to the electrolytic aluminum plant for aluminum electrolyte production, and/or returned to the leaching process.
  • step S1 the aluminum electrolyte is pulverized and sieved through a 80-120 mesh sieve.
  • the aluminum electrolyte is an aluminum electrolyte which is mixed with an additive and which is obtained by calcination to change the lithium salt phase to a soluble lithium salt.
  • step S2 the water is distilled water.
  • the pH should be less than 5 at the end of the reaction, and the fluoride ion concentration should be greater than 1 g/L; depending on the composition of the material, nitric acid is appropriately added.
  • step S3 the reaction temperature of the mixed solution is adjusted at 30-80 °C.
  • the fluoride ion concentration is from 1 to 80 g/L.
  • step S3 the pH of the mixed solution is controlled by an acidity meter, and the fluoride ion concentration of the mixed liquid is controlled by the fluorine ion concentration selective electrode.
  • the present invention controls only the Li 2 O, LiF and Li 3 in the aluminum electrolyte by controlling the potential, pH and fluoride ion concentration of the acid solution.
  • Lithium salt such as AlF 6 is leached without dissolving or leaching other components in the aluminum electrolyte, thereby separating the lithium salt from the electrolyte main body, thereby efficiently extracting lithium element in the aluminum electrolyte, and recovering the lithium salt in the aluminum electrolyte. It has the possibility of reality, is economically feasible, and realizes the recovery of high value-added lithium salt. At the same time, it can obtain industrial electrolytes with higher purity and suitable for electrolytic aluminum production, greatly reducing the energy consumption and comprehensive average extraction cost of electrolytic aluminum production. Application promotion in industrial production.
  • the raw materials used in the invention are all common raw materials in the chemical industry, and the price is low.
  • the process of the invention is simple. By controlling the fluoride ion concentration, potential and pH value of the leaching process solution, selective leaching (lithium salt equivalent LiF dissolution rate) can be realized. At 70-99%, the electrolyte dissolution rate is less than 10%), the production cost is lowered, and various substances can be separated, and the obtained substance has high purity.
  • the invention is based on the purpose of extracting lithium element in aluminum electrolyte, and successfully studies the method for extracting lithium element in aluminum electrolyte by selective leaching of nitric acid, solving the problem of lithium element in the aluminum electrolysis industry, increasing the benefit and improving the aluminum in China.
  • the comprehensive level of the electrolysis industry has also expanded the supply of lithium salt resources in China.
  • the present invention provides a method for selective nitric acid leaching of lithium in an aluminum electrolyte, comprising the steps of:
  • the aluminum electrolyte containing lithium element is pulverized, sieved through a 80-120 mesh sieve, and sieved to perform acid leaching.
  • the selected aluminum electrolyte may be an aluminum electrolyte directly from the electrolytic cell of the electrolytic aluminum plant, or may be mixed with an aluminum electrolyte raw material from an electrolytic cell of an electrolytic aluminum plant and an additive, and subjected to high temperature baking treatment to make insoluble lithium in the aluminum electrolyte.
  • the aluminum electrolyte obtained after the salt is sufficiently converted into a soluble lithium salt, that is, a transition electrolyte which changes the aluminum lithium salt phase to a soluble lithium salt.
  • the above additive selects an alkali metal oxide other than lithium, an alkali metal oxyacid salt other than lithium which can be converted into an alkali metal oxide under high-temperature calcination conditions, and an alkali metal halide other than lithium.
  • One or more kinds are mixed according to the kind of the additive, the molecular ratio of the aluminum electrolyte, and the lithium salt content in the aluminum electrolyte, and satisfy the following conditions: ensuring that the alkali metal fluoride contained in the aluminum electrolyte in the mixture is directly added
  • the molar ratio of the alkali metal fluoride and the additive to the alkali metal fluoride which can be converted under high temperature calcination conditions to aluminum fluoride ie, (LiF+NaF+KF)/AlF 3 >3) is greater than 3.
  • the mixture is compacted or pelletized and calcined at 300-1200 ° C for 3-5 h. During the calcination, the insoluble lithium salt in the aluminum electro
  • the alkali metal oxide other than lithium may be selected from one of sodium oxide and potassium oxide or a mixture of both.
  • the alkali metal oxide other than lithium may be selected from sodium oxide, potassium oxide or a mixture of both.
  • the alkali metal halide other than lithium may be selected from one or more of NaF, NaCl, NaBr, KF, KCl, and KBr.
  • the water may preferably be distilled water, and it is possible to reduce the introduction of new impurity elements into the solution, thereby affecting the leaching of the lithium element.
  • the aluminum electrolyte treated in the step S1 is added to the acid solution obtained in the step S2, and leaching is carried out under stirring and heating. Due to the large fluctuations in the electrolyte composition, the LiF content (3-8%) and the additives added during the electrolyte transition are also different. Therefore, the amount of the aluminum electrolyte added is controlled according to the fluoride ion concentration and the acidity in the solution, wherein The leaching process controls the electrolyte acidity to a pH of less than 4, a fluoride ion concentration of greater than 1 g/L, preferably from 1 to 80 g/L, while monitoring the potential change of the solution.
  • the reaction temperature of the mixed liquor is controlled to be between 20 and 85 ° C, preferably between 30 and 80 ° C.
  • the mixture is stirred by a magnetic stirrer, and the stirring speed is not limited as long as the aluminum electrolyte and the acid solution can be uniformly mixed to promote the elution of lithium in the aluminum electrolyte.
  • the pH of the mixture is controlled by a pH meter, and the fluoride ion concentration of the mixture is controlled by a fluoride ion concentration selection electrode.
  • the pH should be less than 5 and the fluoride ion concentration should be greater than 1 g/L. According to the material composition, appropriate amount of nitric acid is added.
  • the mixed solution after the reaction is filtered and washed a plurality of times (at least two or three times) to obtain a primary filtrate and a primary filtrate after the reaction.
  • Filtration can separate an acid solution containing a large amount of a lithium salt and a very small amount of an aluminum electrolyte component from a precipitate composed of other components of the aluminum electrolyte. Repeated washing twice or three times with distilled water can extract and recover high value-added lithium salt, and at the same time obtain a high purity aluminum electrolyte.
  • the primary filtrate is used for extracting lithium element, and the primary filter is washed, dried, returned to the electrolytic aluminum plant for aluminum electrolyte production, and/or returned to the leaching process.
  • the primary filter After the primary filter is washed and washed with distilled water, it can be returned to the electrolytic aluminum plant as a raw material to produce aluminum electrolyte, or it can be returned to the leaching process of leaching lithium element by the nitric acid solution, and the cycle is repeated, thereby improving the recovery rate of lithium element.
  • the present invention controls only the Li 2 O, LiF and Li 3 in the aluminum electrolyte by controlling the potential, pH and fluoride ion concentration of the acid solution.
  • Lithium salt such as AlF 6 is leached without dissolving or leaching other components in the aluminum electrolyte, thereby separating the lithium salt from the electrolyte main body, thereby efficiently extracting lithium element in the aluminum electrolyte, and recovering the lithium salt in the aluminum electrolyte. It has the possibility of reality, is economically feasible, and realizes the recovery of high value-added lithium salt. At the same time, it can obtain industrial electrolytes with higher purity and suitable for electrolytic aluminum production, greatly reducing the energy consumption and comprehensive average extraction cost of electrolytic aluminum production. Application promotion in industrial production.
  • the raw materials used in the invention are all common raw materials in the chemical industry, and the price is low.
  • the process of the invention is simple. By controlling the fluoride ion concentration, potential and pH value of the leaching process solution, selective leaching (lithium salt equivalent LiF dissolution rate) can be realized. At 78-99%, the electrolyte dissolution rate is less than 10%), the production cost is lowered, and various substances can be separated, and the obtained substance has high purity.
  • the invention is based on the purpose of extracting lithium element in aluminum electrolyte, and successfully studies the method for extracting lithium element in aluminum electrolyte by selective leaching of nitric acid, solving the problem of lithium element in the aluminum electrolysis industry, increasing the benefit and improving the aluminum in China.
  • the comprehensive level of the electrolysis industry has also expanded the supply of lithium salt resources in China.
  • the following exemplary embodiment takes the extraction of aluminum electrolyte samples from some electrolytic aluminum plant 300 kA electrolytic cells, 400 kA electrolytic cells and 200 kA electrolytic cells, respectively.
  • the sample is directly crushed and analyzed by grinding.
  • the element composition and content of the electrolyte are expressed by molecular ratio, alumina concentration, calcium fluoride concentration, lithium fluoride concentration and the like.
  • the embodiments are as follows:
  • the aluminum electrolyte powder Take 10g of aluminum electrolyte (the content of LiF in the electrolyte is 5%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and dispose 100ml of acid solution with nitric acid and distilled water, the pH value of the acid solution 3, the potential is 0.05V, the aluminum electrolyte powder is placed into the above acid solution, heated to 60 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH value 4, When the fluoride ion concentration was 2 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 99%, and the dissolution rate of the electrolyte was 8%.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 90%, and the electrolyte dissolution rate was 10%.
  • the aluminum electrolyte powder Take 10kg of aluminum electrolyte (the content of LiF in the electrolyte is 4%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and arrange 100L acid solution with nitric acid and distilled water.
  • the pH value of the acid solution is 2, the potential is 0.015V
  • the aluminum electrolyte powder is placed in the above acid solution, heated to 85 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH is 4, When the fluoride ion concentration was 30 g/L, the leaching was completed.
  • the mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 80%, and the electrolyte dissolution rate was 6%.
  • the aluminum electrolyte powder Take 150kg of aluminum electrolyte (the content of LiF in the electrolyte is 4%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and arrange 1000L acid solution with nitric acid and distilled water.
  • the pH value of the acid solution is 1, the potential is 0.18V
  • the aluminum electrolyte powder is placed into the above acid solution, heated to 40 ° C, stirred with a magnetic stirrer, control the pH value of the solution and fluoride ion concentration, when the solution pH value 4, fluoride ion At a concentration of 25 g/L, the leaching ended.
  • the mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 88%, and the dissolution rate of the electrolyte was 8%.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 78%, and the electrolyte dissolution rate was 9%.
  • the aluminum electrolyte powder Take 2kg of aluminum electrolyte (the content of LiF in the electrolyte is 5%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and arrange 30L acid solution with nitric acid and distilled water.
  • the pH value of the acid solution is 2, the potential is 0.5V
  • the aluminum electrolyte powder is put into the above acid solution, heated to 30 ° C, stirred with a magnetic stirrer, control the pH value of the solution and the fluoride ion concentration, when the pH value of the solution is 3.8, the potential is At 1.5 V, when the fluoride ion concentration was 1 g/L, the leaching was completed.
  • the mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 83%, and the electrolyte dissolution rate was 5%.
  • the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve.
  • the pH value of the acid solution is 1, the potential is 0.3V
  • the aluminum electrolyte powder is placed in the above acid solution, heated to 80 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH is 1.5, When the fluoride ion concentration was 65 g/L, the leaching was completed.
  • the mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
  • the dissolution rate of LiF in the lithium salt in the electrolyte was 86%, and the electrolyte dissolution rate was 7%.
  • the dissolution rate of LiF in the electrolyte obtained in Example 1 was the highest, the height was 99%, the obtained aluminum electrolyte dissolution rate was 8%, and the purity was relatively high.
  • the extraction of lithium ions in the aluminum electrolyte is optimal.

Abstract

Disclosed is a method for the selective nitric acid leaching of lithium elements in an aluminum electrolyte, comprising the following steps: S1. pulverizing and sieving an aluminum electrolyte containing lithium elements; S2. mixing nitric acid with water, and adjusting the pH value of the acid solution to be less than 4 and the potential to be between 0.015-0.8 V; S3. adding the aluminum electrolyte to the acid solution, stirring and heating same for leaching, wherein the reaction temperature is 20-85ºC, and the addition amount of the aluminum electrolyte is controlled depending on the fluoride ion concentration and acidity in the solution, with the acidity being of a pH value less than 4 and the fluoride ion concentration being greater than 1 g/L; S4. filtering and washing the mixed solution to obtain a filtrate and a filtered substance; and S5. using the filtrate for extracting the lithium elements, and washing and drying the filtered substance, and then returning same to the aluminum electrolysis plant for producing the aluminum electrolyte, and/or returning to the leaching process.

Description

一种铝电解质中锂元素选择性硝酸浸出的方法Method for selectively leaching lithium element in aluminum electrolyte 技术领域Technical field
本发明涉及铝电解质提取回收技术领域，涉及一种采用硝酸选择性浸出铝电解质中锂元素的方法。The invention relates to the technical field of aluminum electrolyte extraction and recovery, and relates to a method for selectively leaching lithium element in an aluminum electrolyte by using nitric acid.
背景技术Background technique
我国电解铝工业的迅速发展，对铝土矿资源的需求量急剧增加。我国高品位铝土矿已经面临枯竭，只有大量的中低品位铝土矿被开釆利用，生产冶金级氧化铝。这种中低品位铝土矿中含有大量的碱金属元素，特别是我国铝土矿主要产区的铝土矿中，锂盐含量较高。大量含有锂盐的氧化铝作为原料用于电解铝生产，导致铝电解槽中的电解质成分发生变化，锂盐在电解质中大量富集，降低电解质初晶温度和氧化铝溶解度，造成铝电解温度下降，炉底沉淀增加，电流效率下降，吨铝能耗增加，直接影响我国铝电解工业的经济效益，是我国铝电解工业亟待解决的问题。因此去除铝电解质中的锂元素，对我国铝电解工业的发展具有重要意义。于此同时，锂盐的工业应用领域不断扩展，如锂电池、铝锂合金、溴化锂空调、原子能工业、有机合成等，对锂盐的需求迅猛发展，锂资源也面临挑战。如果能将含铝电解质作为锂盐资源，提取其中的锂盐，对我国锂盐工业的发展也具有重要意义。The rapid development of China's electrolytic aluminum industry has dramatically increased the demand for bauxite resources. China's high-grade bauxite mines have been exhausted, and only a large number of low-grade bauxite mines have been exploited to produce metallurgical grade alumina. This medium-low grade bauxite contains a large amount of alkali metal elements, especially in the bauxite mines in the main bauxite producing areas of China, and the lithium salt content is relatively high. A large amount of alumina containing lithium salt is used as raw material for electrolytic aluminum production, which causes the electrolyte composition in the aluminum electrolytic cell to change. The lithium salt is greatly enriched in the electrolyte, reducing the initial crystal temperature of the electrolyte and the solubility of the alumina, causing the temperature of the aluminum electrolysis to decrease. The increase in furnace bottom sedimentation, the decrease of current efficiency and the increase of energy consumption per ton of aluminum directly affect the economic benefits of China's aluminum electrolysis industry, which is an urgent problem to be solved in China's aluminum electrolysis industry. Therefore, the removal of lithium in the aluminum electrolyte is of great significance to the development of China's aluminum electrolysis industry. At the same time, the industrial application of lithium salt continues to expand, such as lithium batteries, aluminum-lithium alloys, lithium bromide air conditioners, atomic energy industry, organic synthesis, etc., the demand for lithium salt is rapidly developing, and lithium resources are also facing challenges. If the aluminum-containing electrolyte can be used as a lithium salt resource, the lithium salt extracted from it is also of great significance to the development of the lithium salt industry in China.
目前，采用硝酸溶液可以使将铝电解质中的锂盐浸出，但是这种浸方式不仅会浸出锂盐，而且会将铝电解质中的所有组分都浸出出来，如此，不仅增加了酸消耗量，而且后续的锂盐与其他组分分离困难，造成生产成本的大幅度增加。At present, the lithium salt in the aluminum electrolyte can be leached by using a nitric acid solution, but this immersion method not only leaches out the lithium salt, but also leaches all the components in the aluminum electrolyte, thus not only increasing the acid consumption, Moreover, the subsequent separation of the lithium salt from other components is difficult, resulting in a substantial increase in production costs.
综上所述，亟需提出一种能够选择性浸出锂盐，回收高附加值锂盐，同时得到纯度较高适用于铝电解质生产的工业电解质，降低电解铝生产的能耗，降低综合平均提取费用的铝电解质中锂元素选择性硝酸浸出的方法。In summary, it is urgent to propose a method for selectively leaching lithium salts, recovering high value-added lithium salts, and obtaining industrial electrolytes with higher purity for aluminum electrolyte production, reducing energy consumption of electrolytic aluminum production, and reducing integrated average extraction. A method for the selective leaching of lithium by lithium in the aluminum electrolyte at a cost.
发明内容Summary of the invention
(一)要解决的技术问题(1) Technical problems to be solved
为了解决现有技术的上述问题，本发明提供一种铝电解质中锂元素选择性硝酸浸出的方法，该方法能够有效提取电解质中的锂元素，回收高附加值锂盐，同时得到纯度较高适用于铝电解质生产的工业电解质，降低电解铝生产的能耗和提取成本。In order to solve the above problems of the prior art, the present invention provides a method for selectively leaching lithium elements in an aluminum electrolyte, which is capable of efficiently extracting lithium ions in an electrolyte, recovering high value-added lithium salts, and obtaining high purity at the same time. The industrial electrolyte produced by aluminum electrolyte reduces the energy consumption and extraction cost of electrolytic aluminum production.
(二)技术方案(2) Technical plan
为了达到上述目的，本发明采用以下技术方案：In order to achieve the above object, the present invention adopts the following technical solutions:
本发明提供一种铝电解质中锂元素选择性硝酸浸出的方法，包括以下步骤：The invention provides a method for selective nitric acid leaching of lithium element in an aluminum electrolyte, comprising the following steps:
S1、将含有锂元素的铝电解质粉碎并筛分；S1, pulverizing and sieving an aluminum electrolyte containing lithium element;
S2、将硝酸与水混合，并调整酸溶液的pH值小于4，电位在0.015-0.8V之间；S2, mixing nitric acid with water, and adjusting the pH of the acid solution to be less than 4, and the potential is between 0.015-0.8V;
S3、将步骤S1处理后的铝电解质加入到步骤S2得到的酸溶液中，搅拌并加热进行浸出，在浸出过程中，反应温度为20-85℃，铝电解质的加入量依据溶液中氟离子浓度和酸度综合控制，其中，酸度为pH值小于4，氟离子浓度大于1g/L；S3, adding the aluminum electrolyte treated in step S1 to the acid solution obtained in step S2, stirring and heating to carry out leaching, in the leaching process, the reaction temperature is 20-85 ° C, the amount of aluminum electrolyte added according to the fluoride ion concentration in the solution And comprehensive control of acidity, wherein the acidity is pH less than 4, and the fluoride ion concentration is greater than 1 g/L;
S4、反应结束后，将反应后的混合液进行过滤、洗涤，得到反应后一次滤液和一次过滤物；After the reaction is completed, the mixed solution after the reaction is filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction;
S5、一次滤液用于提取锂元素，一次过滤物经洗涤、干燥，返回电解铝厂用于铝电解质生产，和/或，返回浸出过程中。S5. The primary filtrate is used for extracting lithium element, and the primary filter is washed, dried, returned to the electrolytic aluminum plant for aluminum electrolyte production, and/or returned to the leaching process.
根据本发明，在步骤S1中，所述铝电解质粉碎后，过80-120目筛进行筛分。According to the invention, in step S1, the aluminum electrolyte is pulverized and sieved through a 80-120 mesh sieve.
根据本发明，在步骤S1之前，所述铝电解质为其与添加剂混合，并焙烧后得到的改变锂盐物相为可溶性锂盐的铝电解质。According to the present invention, prior to step S1, the aluminum electrolyte is an aluminum electrolyte which is mixed with an additive and which is obtained by calcination to change the lithium salt phase to a soluble lithium salt.
根据本发明，在步骤S2中，所述水采用蒸馏水。According to the invention, in step S2, the water is distilled water.
根据本发明，在步骤S3中，反应结束时pH值应小于5，氟离子浓 度应大于1g/L；根据物料组成不同，适当补充添加硝酸。According to the present invention, in step S3, the pH should be less than 5 at the end of the reaction, and the fluoride ion concentration should be greater than 1 g/L; depending on the composition of the material, nitric acid is appropriately added.
根据本发明，在步骤S3中，调整混合液的反应温度在30-80℃。According to the invention, in step S3, the reaction temperature of the mixed solution is adjusted at 30-80 °C.
根据本发明，在步骤S3中，所述氟离子浓度为1-80g/L。According to the invention, in step S3, the fluoride ion concentration is from 1 to 80 g/L.
根据本发明，在步骤S3中，采用酸度计控制混合液的pH值，采用氟离子浓度选择电极控制混合液的氟离子浓度。According to the present invention, in step S3, the pH of the mixed solution is controlled by an acidity meter, and the fluoride ion concentration of the mixed liquid is controlled by the fluorine ion concentration selective electrode.
(三)有益效果(3) Beneficial effects
本发明的有益效果是：The beneficial effects of the invention are:
与现有采用硝酸溶液将铝电解质中的所有组分都浸出的方法不同，本发明通过控制酸溶液的电位、pH值和氟离子浓度，只将铝电解质中的Li 2O、LiF和Li 3AlF 6等锂盐浸出，而不使铝电解质中的其它成分溶解出来或浸出很少，实现锂盐与电解质主体的分离，从而有效提取铝电解质中的锂元素，使铝电解质中锂盐的回收具有了现实的可能，经济上可行，实现了回收高附加值锂盐，同时可得到纯度较高适用于电解铝生产的工业电解质，大大降低电解铝生产的能耗和综合平均提取费用，适合在工业生产中进行应用推广。 Unlike the existing method of leaching all the components in the aluminum electrolyte with a nitric acid solution, the present invention controls only the Li 2 O, LiF and Li 3 in the aluminum electrolyte by controlling the potential, pH and fluoride ion concentration of the acid solution. Lithium salt such as AlF 6 is leached without dissolving or leaching other components in the aluminum electrolyte, thereby separating the lithium salt from the electrolyte main body, thereby efficiently extracting lithium element in the aluminum electrolyte, and recovering the lithium salt in the aluminum electrolyte. It has the possibility of reality, is economically feasible, and realizes the recovery of high value-added lithium salt. At the same time, it can obtain industrial electrolytes with higher purity and suitable for electrolytic aluminum production, greatly reducing the energy consumption and comprehensive average extraction cost of electrolytic aluminum production. Application promotion in industrial production.
本发明所使用的原料均为化工领域常见原料，价格便宜，本发明的流程简单，通过控制浸出过程溶液的氟离子浓度、电位和pH值，可以实现选择性浸出(锂盐折合的LiF溶出率在70-99％，电解质溶出率低于10％)，降低生产成本，且可分离出多种物质，所得物质纯度较高。The raw materials used in the invention are all common raw materials in the chemical industry, and the price is low. The process of the invention is simple. By controlling the fluoride ion concentration, potential and pH value of the leaching process solution, selective leaching (lithium salt equivalent LiF dissolution rate) can be realized. At 70-99%, the electrolyte dissolution rate is less than 10%), the production cost is lowered, and various substances can be separated, and the obtained substance has high purity.
本发明基于提取铝电解质中锂元素的目的，成功的研究出采用硝酸选择性浸出提取铝电解质中锂元素的方法，为铝电解行业解决了锂元素影响问题，也增加了效益，提升了我国铝电解工业的综合水平，同时扩大了我国锂盐资源供给。The invention is based on the purpose of extracting lithium element in aluminum electrolyte, and successfully studies the method for extracting lithium element in aluminum electrolyte by selective leaching of nitric acid, solving the problem of lithium element in the aluminum electrolysis industry, increasing the benefit and improving the aluminum in China. The comprehensive level of the electrolysis industry has also expanded the supply of lithium salt resources in China.
具体实施方式Detailed ways
为了更好的解释本发明，以便于理解，下面结合具体实施方式，对本发明作详细描述。For a better explanation of the present invention, the present invention will be described in detail below in conjunction with the specific embodiments.
本发明提供一种铝电解质中锂元素选择性硝酸浸出的方法，包括以 下步骤：The present invention provides a method for selective nitric acid leaching of lithium in an aluminum electrolyte, comprising the steps of:
S1、将含有锂元素的铝电解质粉碎，过80-120目筛进行筛分，去筛下料进行酸浸。S1. The aluminum electrolyte containing lithium element is pulverized, sieved through a 80-120 mesh sieve, and sieved to perform acid leaching.
选取的铝电解质可以是直接来自电解铝厂电解槽中的铝电解质，也可以是来自电解铝厂电解槽中的铝电解质原料与添加剂混合，并经高温焙烧处理，使铝电解质中的不可溶性锂盐充分地转化成可溶性锂盐后得到的铝电解质，即改变铝锂盐物相为可溶性锂盐的转型电解质。The selected aluminum electrolyte may be an aluminum electrolyte directly from the electrolytic cell of the electrolytic aluminum plant, or may be mixed with an aluminum electrolyte raw material from an electrolytic cell of an electrolytic aluminum plant and an additive, and subjected to high temperature baking treatment to make insoluble lithium in the aluminum electrolyte. The aluminum electrolyte obtained after the salt is sufficiently converted into a soluble lithium salt, that is, a transition electrolyte which changes the aluminum lithium salt phase to a soluble lithium salt.
上述的添加剂选择除锂之外的碱金属氧化物、在高温焙烧条件下可转化成碱金属氧化物的除锂之外的碱金属含氧酸盐、除锂之外的碱金属卤化物中的一种或多种，根据添加剂的种类、铝电解质的分子比以及铝电解质中锂盐含量的不同进行混料，并满足以下条件：保证混合物料中铝电解质含有的碱金属氟化物、添加剂直接添加的碱金属氟化物、添加剂在高温焙烧条件下可转化成的碱金属氟化物三者与氟化铝的摩尔比(即，(LiF+NaF+KF)/AlF 3>3)大于3。将混合物料压实或制团，在300～1200℃下焙烧3-5h，焙烧过程中铝电解质中不可溶性锂盐转化成可溶性锂盐。 The above additive selects an alkali metal oxide other than lithium, an alkali metal oxyacid salt other than lithium which can be converted into an alkali metal oxide under high-temperature calcination conditions, and an alkali metal halide other than lithium. One or more kinds are mixed according to the kind of the additive, the molecular ratio of the aluminum electrolyte, and the lithium salt content in the aluminum electrolyte, and satisfy the following conditions: ensuring that the alkali metal fluoride contained in the aluminum electrolyte in the mixture is directly added The molar ratio of the alkali metal fluoride and the additive to the alkali metal fluoride which can be converted under high temperature calcination conditions to aluminum fluoride (ie, (LiF+NaF+KF)/AlF 3 >3) is greater than 3. The mixture is compacted or pelletized and calcined at 300-1200 ° C for 3-5 h. During the calcination, the insoluble lithium salt in the aluminum electrolyte is converted into a soluble lithium salt.
其中，除锂之外的碱金属氧化物可选择氧化钠、氧化钾中的一种或二者的混合物。除锂之外的碱金属氧化物可选择氧化钠、氧化钾中的一种或二者的混合物。除锂之外的碱金属卤化物可以选择NaF，NaCl，NaBr，KF，KCl，KBr中的一种或多种。Among them, the alkali metal oxide other than lithium may be selected from one of sodium oxide and potassium oxide or a mixture of both. The alkali metal oxide other than lithium may be selected from sodium oxide, potassium oxide or a mixture of both. The alkali metal halide other than lithium may be selected from one or more of NaF, NaCl, NaBr, KF, KCl, and KBr.
S2、将工业硝酸与水混合，并调整酸溶液的pH值小于4，电位在0.015-0.8V之间。S2, mixing industrial nitric acid with water, and adjusting the pH of the acid solution to be less than 4, and the potential is between 0.015 and 0.8V.
水可以优选蒸馏水，能够减少新的杂质元素被引入溶液中，从而对锂元素的浸出产生影响。The water may preferably be distilled water, and it is possible to reduce the introduction of new impurity elements into the solution, thereby affecting the leaching of the lithium element.
S3、将步骤S1处理后的铝电解质加入到步骤S2得到的酸溶液中，在搅拌和加热的条件下进行浸出。由于电解质成分存在很大的波动，主要是LiF含量(3-8％)以及在电解质转型时加入的添加剂也不同，因此， 铝电解质的加入量依据溶液中氟离子浓度和酸度综合控制，其中，浸出过程控制电解质酸度为pH值小于4，氟离子浓度大于1g/L，优选1-80g/L，同时监测溶液的电位变化。控制混合液的反应温度在20-85℃之间，优选30-80℃。S3. The aluminum electrolyte treated in the step S1 is added to the acid solution obtained in the step S2, and leaching is carried out under stirring and heating. Due to the large fluctuations in the electrolyte composition, the LiF content (3-8%) and the additives added during the electrolyte transition are also different. Therefore, the amount of the aluminum electrolyte added is controlled according to the fluoride ion concentration and the acidity in the solution, wherein The leaching process controls the electrolyte acidity to a pH of less than 4, a fluoride ion concentration of greater than 1 g/L, preferably from 1 to 80 g/L, while monitoring the potential change of the solution. The reaction temperature of the mixed liquor is controlled to be between 20 and 85 ° C, preferably between 30 and 80 ° C.
在浸出过程中，采用磁力搅拌器搅拌混合液，搅拌速度不限，只要能够使铝电解质与酸溶液均匀混合，以促进铝电解质中的锂元素溶出即可。采用酸度计控制混合液的pH值，采用氟离子浓度选择电极控制混合液的氟离子浓度。反应结束时pH值应小于5，氟离子浓度应大于1g/L。根据物料组成不同，适当补充添加适量的硝酸。In the leaching process, the mixture is stirred by a magnetic stirrer, and the stirring speed is not limited as long as the aluminum electrolyte and the acid solution can be uniformly mixed to promote the elution of lithium in the aluminum electrolyte. The pH of the mixture is controlled by a pH meter, and the fluoride ion concentration of the mixture is controlled by a fluoride ion concentration selection electrode. At the end of the reaction, the pH should be less than 5 and the fluoride ion concentration should be greater than 1 g/L. According to the material composition, appropriate amount of nitric acid is added.
S4、反应结束后，将反应后的混合液进行过滤、多次(至少两三次)洗涤，得到反应后一次滤液和一次过滤物。S4. After the reaction is completed, the mixed solution after the reaction is filtered and washed a plurality of times (at least two or three times) to obtain a primary filtrate and a primary filtrate after the reaction.
过滤可以将溶有大量锂盐、极少量的铝电解质成分的酸溶液与铝电解质其他成分组成的沉淀物分离。采用蒸馏水重复洗涤两三次，可提取回收高附加值的锂盐，同时得到纯度高的铝电解质。Filtration can separate an acid solution containing a large amount of a lithium salt and a very small amount of an aluminum electrolyte component from a precipitate composed of other components of the aluminum electrolyte. Repeated washing twice or three times with distilled water can extract and recover high value-added lithium salt, and at the same time obtain a high purity aluminum electrolyte.
S5、一次滤液用于提取锂元素，一次过滤物经洗涤、干燥，返回电解铝厂用于铝电解质生产，和/或，返回浸出过程中。S5. The primary filtrate is used for extracting lithium element, and the primary filter is washed, dried, returned to the electrolytic aluminum plant for aluminum electrolyte production, and/or returned to the leaching process.
一次过滤物经蒸馏水洗涤、烘干后可以返回电解铝厂作为原料生产铝电解质，也可以返回硝酸溶液浸出锂元素的浸出过程，多次循环，从而提高锂元素的回收率。After the primary filter is washed and washed with distilled water, it can be returned to the electrolytic aluminum plant as a raw material to produce aluminum electrolyte, or it can be returned to the leaching process of leaching lithium element by the nitric acid solution, and the cycle is repeated, thereby improving the recovery rate of lithium element.
与现有采用硝酸溶液将铝电解质中的所有组分都浸出的方法不同，本发明通过控制酸溶液的电位、pH值和氟离子浓度，只将铝电解质中的Li 2O、LiF和Li 3AlF 6等锂盐浸出，而不使铝电解质中的其它成分溶解出来或浸出很少，实现锂盐与电解质主体的分离，从而有效提取铝电解质中的锂元素，使铝电解质中锂盐的回收具有了现实的可能，经济上可行，实现了回收高附加值锂盐，同时可得到纯度较高适用于电解铝生产的工业电解质，大大降低电解铝生产的能耗和综合平均提取费用，适合在工业生产中进行应用推广。 Unlike the existing method of leaching all the components in the aluminum electrolyte with a nitric acid solution, the present invention controls only the Li 2 O, LiF and Li 3 in the aluminum electrolyte by controlling the potential, pH and fluoride ion concentration of the acid solution. Lithium salt such as AlF 6 is leached without dissolving or leaching other components in the aluminum electrolyte, thereby separating the lithium salt from the electrolyte main body, thereby efficiently extracting lithium element in the aluminum electrolyte, and recovering the lithium salt in the aluminum electrolyte. It has the possibility of reality, is economically feasible, and realizes the recovery of high value-added lithium salt. At the same time, it can obtain industrial electrolytes with higher purity and suitable for electrolytic aluminum production, greatly reducing the energy consumption and comprehensive average extraction cost of electrolytic aluminum production. Application promotion in industrial production.
本发明所使用的原料均为化工领域常见原料，价格便宜，本发明的流程简单，通过控制浸出过程溶液的氟离子浓度、电位和pH值，可以实现选择性浸出(锂盐折合的LiF溶出率在78-99％，电解质溶出率低于10％)，降低生产成本，且可分离出多种物质，所得物质纯度较高。The raw materials used in the invention are all common raw materials in the chemical industry, and the price is low. The process of the invention is simple. By controlling the fluoride ion concentration, potential and pH value of the leaching process solution, selective leaching (lithium salt equivalent LiF dissolution rate) can be realized. At 78-99%, the electrolyte dissolution rate is less than 10%), the production cost is lowered, and various substances can be separated, and the obtained substance has high purity.
本发明基于提取铝电解质中锂元素的目的，成功的研究出采用硝酸选择性浸出提取铝电解质中锂元素的方法，为铝电解行业解决了锂元素影响问题，也增加了效益，提升了我国铝电解工业的综合水平，同时扩大了我国锂盐资源供给。The invention is based on the purpose of extracting lithium element in aluminum electrolyte, and successfully studies the method for extracting lithium element in aluminum electrolyte by selective leaching of nitric acid, solving the problem of lithium element in the aluminum electrolysis industry, increasing the benefit and improving the aluminum in China. The comprehensive level of the electrolysis industry has also expanded the supply of lithium salt resources in China.
以下典型实施例以提取铝电解质样品分别来自某些电解铝厂300kA电解槽，400kA电解槽和200kA电解槽为例。样品直接破碎、磨细分析，电解质的元素组成及含量用分子比，氧化铝浓度，氟化钙浓度，氟化锂浓度等来表示。各实施例具体如下：The following exemplary embodiment takes the extraction of aluminum electrolyte samples from some electrolytic aluminum plant 300 kA electrolytic cells, 400 kA electrolytic cells and 200 kA electrolytic cells, respectively. The sample is directly crushed and analyzed by grinding. The element composition and content of the electrolyte are expressed by molecular ratio, alumina concentration, calcium fluoride concentration, lithium fluoride concentration and the like. The embodiments are as follows:
实施例1Example 1
取10g铝电解质(电解质中LiF的含量为5％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置100ml酸溶液，酸溶液的pH值为3，电位为0.05V，将铝电解质粉末放入到上述的酸溶液中，加热到60℃，用磁力搅拌器进行搅拌，控制溶液电位、pH值和氟离子浓度，当溶液pH值为4，氟离子浓度为2g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 10g of aluminum electrolyte (the content of LiF in the electrolyte is 5%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and dispose 100ml of acid solution with nitric acid and distilled water, the pH value of the acid solution 3, the potential is 0.05V, the aluminum electrolyte powder is placed into the above acid solution, heated to 60 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH value 4, When the fluoride ion concentration was 2 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为99％，电解质溶出率为8％。According to the analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 99%, and the dissolution rate of the electrolyte was 8%.
实施例2Example 2
取500g铝电解质(电解质中LiF的含量为7％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置1L酸溶液， 酸溶液的pH值为2，电位为0.1V，将铝电解质粉末放入到上述的酸溶液中，加热到70℃，用磁力搅拌器进行搅拌，控制溶液电位、pH值和氟离子浓度，当溶液pH值为1，氟离子浓度为50g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 500g of aluminum electrolyte (the content of LiF in the electrolyte is 7%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve. Configure 1L acid solution with nitric acid and distilled water. The pH value of the acid solution is 2, the potential is 0.1V, the aluminum electrolyte powder is placed in the above acid solution, heated to 70 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH value 1, When the fluoride ion concentration was 50 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为90％，电解质溶出率为10％。According to analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 90%, and the electrolyte dissolution rate was 10%.
实施例3Example 3
取10kg铝电解质(电解质中LiF的含量为4％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置100L酸溶液，酸溶液的pH值为2，电位为0.015V，将铝电解质粉末放入到上述的酸溶液中，加热到85℃，用磁力搅拌器进行搅拌，控制溶液电位、pH值和氟离子浓度，当溶液pH值为4，氟离子浓度为30g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 10kg of aluminum electrolyte (the content of LiF in the electrolyte is 4%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and arrange 100L acid solution with nitric acid and distilled water. The pH value of the acid solution is 2, the potential is 0.015V, the aluminum electrolyte powder is placed in the above acid solution, heated to 85 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH is 4, When the fluoride ion concentration was 30 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为80％，电解质溶出率为6％。According to analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 80%, and the electrolyte dissolution rate was 6%.
实施例4Example 4
取150kg铝电解质(电解质中LiF的含量为4％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置1000L酸溶液，酸溶液的pH值为1，电位为0.18V，将铝电解质粉末放入到上述的酸溶液中，加热到40℃，用磁力搅拌器进行搅拌，控制溶液pH值和氟离子浓度，当溶液pH值为4，氟离子浓度为25g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 150kg of aluminum electrolyte (the content of LiF in the electrolyte is 4%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and arrange 1000L acid solution with nitric acid and distilled water. The pH value of the acid solution is 1, the potential is 0.18V, the aluminum electrolyte powder is placed into the above acid solution, heated to 40 ° C, stirred with a magnetic stirrer, control the pH value of the solution and fluoride ion concentration, when the solution pH value 4, fluoride ion At a concentration of 25 g/L, the leaching ended. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为88％，电解质溶出率为8％。According to the analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 88%, and the dissolution rate of the electrolyte was 8%.
实施例5Example 5
取500g铝电解质(电解质中LiF的含量为7％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置100ml酸溶液，酸溶液的pH值为2，电位为0.8V，将铝电解质粉末放入到上述的酸溶液中，加热到20℃，用磁力搅拌器进行搅拌，控制溶液电位、pH值和氟离子浓度，当溶液pH值为3.9，氟离子浓度为80g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 500g of aluminum electrolyte (the content of LiF in the electrolyte is 7%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and dispose 100ml of acid solution with nitric acid and distilled water, the pH value of the acid solution 2, the potential is 0.8V, the aluminum electrolyte powder is placed in the above acid solution, heated to 20 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH is 3.9, When the fluoride ion concentration was 80 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为78％，电解质溶出率为9％。According to analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 78%, and the electrolyte dissolution rate was 9%.
实施例6Example 6
取2kg铝电解质(电解质中LiF的含量为5％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置30L酸溶液，酸溶液的pH值为2，电位为0.5V，将铝电解质粉末放入到上述的酸溶液中，加热到30℃，用磁力搅拌器进行搅拌，控制溶液pH值和氟离子浓度，当溶液pH值为3.8，电位为1.5V，氟离子浓度为1g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 2kg of aluminum electrolyte (the content of LiF in the electrolyte is 5%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve, and arrange 30L acid solution with nitric acid and distilled water. The pH value of the acid solution is 2, the potential is 0.5V, the aluminum electrolyte powder is put into the above acid solution, heated to 30 ° C, stirred with a magnetic stirrer, control the pH value of the solution and the fluoride ion concentration, when the pH value of the solution is 3.8, the potential is At 1.5 V, when the fluoride ion concentration was 1 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为83％，电解质溶出率为5％。According to analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 83%, and the electrolyte dissolution rate was 5%.
实施例7Example 7
取800g铝电解质(电解质中LiF的含量为4％)，通过破碎、磨细、过80-120目筛筛分后得到铝电解质粉末，用硝酸与蒸馏水配置100ml酸溶液，酸溶液的pH值为1，电位为0.3V，将铝电解质粉末放入到上述的 酸溶液中，加热到80℃，用磁力搅拌器进行搅拌，控制溶液电位、pH值和氟离子浓度，当溶液pH值为1.5，氟离子浓度为65g/L时，浸出结束。将反应后的混合液进行过滤、洗涤，得到反应后的一次滤液和一次过滤物。Take 800g of aluminum electrolyte (the content of LiF in the electrolyte is 4%), obtain the aluminum electrolyte powder by crushing, grinding and sieving through 80-120 mesh sieve. Configure 100ml acid solution with nitric acid and distilled water. The pH value of the acid solution is 1, the potential is 0.3V, the aluminum electrolyte powder is placed in the above acid solution, heated to 80 ° C, stirred with a magnetic stirrer, control solution potential, pH and fluoride ion concentration, when the solution pH is 1.5, When the fluoride ion concentration was 65 g/L, the leaching was completed. The mixed solution after the reaction was filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction.
经分析检测，电解质中锂盐折合的LiF的溶出率为86％，电解质溶出率为7％。According to analysis, the dissolution rate of LiF in the lithium salt in the electrolyte was 86%, and the electrolyte dissolution rate was 7%.
从上述实施例1-7可以看出，实施例1获得的电解质中LiF的溶出率最高，高达到99％，得到的铝电解质溶出率为8％，纯度也相对较高。提取回收铝电解质中的锂元素效果最优。As can be seen from the above Examples 1-7, the dissolution rate of LiF in the electrolyte obtained in Example 1 was the highest, the height was 99%, the obtained aluminum electrolyte dissolution rate was 8%, and the purity was relatively high. The extraction of lithium ions in the aluminum electrolyte is optimal.
需要理解的是，以上对本发明的具体实施例进行的描述只是为了说明本发明的技术路线和特点，其目的在于让本领域内的技术人员能够了解本发明的内容并据以实施，但本发明并不限于上述特定实施方式。凡是在本发明权利要求的范围内做出的各种变化或修饰，都应涵盖在本发明的保护范围内。The above description of the specific embodiments of the present invention is intended to be illustrative only, and the invention is intended to be understood by those skilled in the art It is not limited to the specific embodiments described above. Various changes or modifications may be made without departing from the scope of the invention.

Claims (7)

  1. 一种铝电解质中锂元素选择性硝酸浸出的方法，其特征在于，包括以下步骤：A method for selectively leaching lithium element in a lithium electrolyte, characterized by comprising the steps of:
    S1、将含有锂元素的铝电解质粉碎并筛分；S1, pulverizing and sieving an aluminum electrolyte containing lithium element;
    S2、将硝酸与水混合，并调整酸溶液的pH值小于4，电位在0.015-0.8V之间；S2, mixing nitric acid with water, and adjusting the pH of the acid solution to be less than 4, and the potential is between 0.015-0.8V;
    S3、将步骤S1处理后的铝电解质加入到步骤S2得到的酸溶液中，搅拌并加热进行浸出，在浸出过程中，反应温度为20-85℃，铝电解质的加入量依据溶液中氟离子浓度和酸度综合控制，其中，酸度为pH值小于4，氟离子浓度大于1g/L；S3, adding the aluminum electrolyte treated in step S1 to the acid solution obtained in step S2, stirring and heating to carry out leaching, in the leaching process, the reaction temperature is 20-85 ° C, the amount of aluminum electrolyte added according to the fluoride ion concentration in the solution And comprehensive control of acidity, wherein the acidity is pH less than 4, and the fluoride ion concentration is greater than 1 g/L;
    S4、反应结束后，将反应后的混合液进行过滤、洗涤，得到反应后一次滤液和一次过滤物；After the reaction is completed, the mixed solution after the reaction is filtered and washed to obtain a primary filtrate and a primary filtrate after the reaction;
    S5、一次滤液用于提取锂元素，一次过滤物经洗涤、干燥，返回电解铝厂用于铝电解质生产，和/或，返回浸出过程中。S5. The primary filtrate is used for extracting lithium element, and the primary filter is washed, dried, returned to the electrolytic aluminum plant for aluminum electrolyte production, and/or returned to the leaching process.
  2. 如权利要求1所述的铝电解质中锂元素选择性硝酸浸出的方法，其特征在于：在步骤S1中，所述铝电解质粉碎后，过80-120目筛进行筛分。A method of selectively leaching lithium element in a lithium electrolyte according to claim 1, wherein in the step S1, the aluminum electrolyte is pulverized and sieved through a sieve of 80-120 mesh.
  3. 如权利要求1所述的铝电解质中锂元素选择性硝酸浸出的方法，其特征在于：在步骤S1之前，所述铝电解质为其与添加剂混合，并焙烧后得到的改变锂盐物相为可溶性锂盐的铝电解质。The method for selectively leaching lithium element in the aluminum electrolyte according to claim 1, wherein before the step S1, the aluminum electrolyte is mixed with the additive, and the changed lithium salt phase obtained after calcination is soluble. Aluminum electrolyte of lithium salt.
  4. 如权利要求1所述的铝电解质中锂元素选择性硝酸浸出的方法，其特征在于：在步骤S2中，所述水采用蒸馏水。A method of selectively leaching lithium elemental acid in an aluminum electrolyte according to claim 1, wherein in the step S2, the water is distilled water.
  5. 如权利要求1-4任一所述的铝电解质中锂元素选择性硝酸浸出的方法，其特征在于：在步骤S3中，反应结束时pH值应小于5，氟离子浓度应大于1g/L；根据物料组成不同，适当补充添加硝酸。The method for extracting lithium element selective nitric acid in an aluminum electrolyte according to any one of claims 1 to 4, wherein in step S3, the pH value at the end of the reaction should be less than 5, and the fluoride ion concentration should be greater than 1 g/L; Depending on the composition of the material, nitric acid is added as appropriate.
  6. 如权利要求1所述的铝电解质中锂元素选择性硝酸浸出的方法，其特征在于：在步骤S3中，调整混合液的反应温度在30-80℃。A method of selectively leaching lithium element in a lithium electrolyte according to claim 1, wherein in step S3, the reaction temperature of the mixed solution is adjusted to be 30 to 80 °C.
  7. 如权利要求1所述的铝电解质中锂元素选择性硝酸浸出的方法，A method of selectively leaching lithium element in a lithium electrolyte according to claim 1,
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