CN115216645B - Method for extracting lithium from electrolytic aluminum waste residue by mixed salt calcination - Google Patents

Abstract

The present invention is to provide a method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method. The electrolytic aluminum waste slag is used as a raw material, potassium and calcium salts are used as auxiliary materials, and a mixed salt calcination method is adopted. Calcification roasting, potassium salt Reburning, alkali leaching, solid-liquid separation, freezing and impurity removal, purification process, the content of other metal impurity ions in the extract is low, easy to separate and extract lithium salt, extract and separate industrial lithium hydroxide and lithium carbonate, the extraction rate It is more than 95%, suitable for industrialization and large-scale production, and improves the market competitiveness of products.

Description

Lithium extraction method from electrolytic aluminum waste slag by mixed salt calcination method

Technical field:

The invention relates to the field of lithium extraction materials for lithium battery new energy technology, and mainly relates to the technology of extracting lithium or lithium salt from electrolytic aluminum waste slag raw materials, especially a method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method.

Background technique:

In response to the vigorous development of new energy in various countries, all countries have invested a lot of material and financial resources in the development and utilization of new energy. The new energy technology and application of lithium battery is an emerging industry strongly supported by the governments of various countries.

Lithium and its compounds are widely used in energy, chemical industry, metallurgy, ceramics, nuclear energy and other fields as energy materials required by new technologies. The global demand for lithium and its compounds is increasing. Therefore, the development of lithium resources and its industrial production is one of the priority industries in the world. At present, the production of lithium carbonate mainly includes two types of technologies: lithium extraction from ore and lithium extraction from brine. The technology of extracting lithium from ore is mature, with high recovery rate and simple process, but it has disadvantages such as high energy consumption, large material flow rate and high cost, while the technology of extracting lithium from salt lake brine is greatly restricted by resource endowment and technical level. However, it is particularly important to extract lithium from lithium-containing solid waste.

"Lithium" is known as "energy metal" and "white oil". Lithium compounds are the basic core raw materials for new energy sources of lithium batteries. Lithium mainly exists in the form of lithium ore resources such as spodumene, lepidolite, lepidolite and phosphate aluminum in natural ores. The technical solutions for extracting lithium or lithium salts from lithium ore resources are very common. However, there are not many other lithium-related materials as raw materials for extracting lithium and its salts.

For example, in the production of aluminum electrolysis, in addition to adding cryolite to the electrolyte, some salts such as fluoride or chloride are also added to improve the properties of the electrolyte and achieve the purpose of improving current efficiency and reducing energy consumption. Commonly used additives One is lithium fluoride. Lithium-containing anhydrous aluminum fluoride and lithium-containing cryolite are currently used in electrolytic aluminum enterprises with good results, which can effectively reduce the initial temperature of the electrolyte, reduce fluorine emissions, and play a role in promoting energy saving and consumption reduction in electrolytic aluminum enterprises. With the use of lithium-containing fluoride salts, lithium-containing electrolytic aluminum waste slag is produced, and its lithium content is 1% to 3% (calculated as Li+). At present, many production enterprises use concentrated sulfuric acid pressure cooking to extract lithium, which has a large amount of hydrogen fluoride. Acid overflow, pollute the environment, high energy consumption of equipment.

For example, Chinese patent announcement number CNCN105293536A discloses a method for extracting lithium from electrolytic aluminum waste residue, which includes the following steps: reacting lithium-containing electrolytic aluminum waste residue with concentrated sulfuric acid at 200-400°C to obtain a mixture A; soaking the mixture A in water Take and filter to obtain filtrate A and filter residue A; add filtrate A to sodium carbonate for alkaline hydrolysis reaction at 20-40°C, and then filter to obtain filtrate B and filter residue B; add water to filter residue B to make slurry and then add lime for caustic After filtration, filtrate C and filter residue C are obtained; CO2 is introduced into the filtrate C in step 4) for carbonization reaction, and then filtered, washed and dried to obtain final product. The impurity ion content in the obtained battery-grade lithium carbonate is low, and the product quality is excellent, which solves the problems of low yield, high production cost and weak market competitiveness in the preparation of battery-grade lithium carbonate by extracting lithium from ore; The new process of high-value and high-quality lithium products has simple process, easy industrial operation, and remarkable economic and social benefits. It can be seen from the technical scheme disclosed in the above-mentioned documents that it uses the electrolytic aluminum waste residue as raw material to extract lithium by concentrated sulfuric acid pressure cooking. The impact of environmental pollution is too great, and the requirements for production equipment are relatively high; the second is that due to the existence of a large amount of hydrofluoric acid in the extracted leachate, the presence of other metal chemical elements in the solution is relatively high, that is, for lithium or For lithium salts, the content of aluminum and copper as impurity elements is higher; subsequent processing is more difficult, resulting in higher production costs.

Therefore, how to provide a method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method is to use electrolytic aluminum waste slag as a raw material and adopt a mixed salt calcination method to find a method with simple technology, low energy consumption and high product quality. , the whole process is a kind of comprehensive utilization of lithium solid waste. In the extraction process, the hydrofluoric acid solution will not have a great impact on the environment, and the content of other metal impurity ions in the extraction solution is not high, and the lithium salt method is easy to separate and extract, realizing the technology of extracting lithium from electrolytic aluminum waste slag. It is applied in industrialization and large-scale production. The production cost of extracting lithium from electrolytic aluminum waste slag is greatly reduced.

Invention content:

The purpose of the present invention is to provide a method for extracting lithium from electrolytic aluminum waste residue by a mixed salt calcination method, which uses electrolytic aluminum waste slag as raw material, potassium and calcium salts as auxiliary materials, and adopts a mixed salt calcination method. Burning, alkali leaching, solid-liquid separation, freezing and impurity removal, and purification processes, the content of other metal impurity ions in the leach solution is low, and the lithium salt is easily separated and extracted, which improves the market competitiveness of the product.

The object of the present invention is to provide a method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method. The electrolytic aluminum waste slag is used as a raw material, potassium and calcium salts are used as auxiliary materials, and a mixed salt calcination method is adopted. Calcination, alkali leaching, solid-liquid separation, freezing to remove impurities, purification process, which includes the following method steps:

1) Crushing and ball milling, the electrolytic aluminum waste residue is mechanically crushed into subdivided materials, mixed with calcium salt after sieving, and then entered into a ball milling device for ball milling treatment, which is a ball milling mixture;

2) Pressing, calcification and roasting, placing step 1) the ball milled mixed material in a press device, pressing it into a brick shape, and then placing it in a tunnel kiln device for calcification and roasting to become a roasting material;

3) Secondary ball milling of the ingredients, the step 2) roasting material and potassium salt are placed in a ball milling device for mixed ball milling to 50-100 mesh, which is the mixture;

4) Secondary roasting, put the mixed material in the rotary kiln device, and roast it through the rotary kiln. The material is then mechanically crushed and ball-milled for clinker, and processed to 80 mesh to 160 mesh, which is roasted fine powder;

5) Alkali leaching treatment, placing the roasted fine powder material, lye and aqueous solution in a stirring device, fully stirring and mixing, and performing leaching treatment to obtain a lithium hydroxide solution leaching solution;

6) Solid-liquid separation and countercurrent washing, the lithium hydroxide solution leachate is subjected to solid-liquid separation through a filter device to obtain a filter residue and a filtrate; the filter residue is subjected to countercurrent washing for several times, and then filtered through a plate and frame filter to obtain a washing solution and a washing solution. slag, control the concentration of lithium ions in the washing slag to be low;

7) freezing treatment, fully mixing the filtrate and washing liquid prepared in step 6) to be a lithium-making solution, and processing the lithium-making solution through a freezing process to become a mixed salt of aluminum potassium sulfate dodecahydrate, and then centrifuging to obtain lithium purification fluid;

8) Rinsing treatment, the aluminum sulfate potassium salt dodecahydrate obtained after step 7) centrifugation is continuously rinsed several times with clear water to obtain the washing liquid and the washing aluminum sulfate potassium salt dodecahydrate, and the washing liquid is the next step 5 ) for alkaline leaching treatment;

9) In-depth purification to produce lithium hydroxide or lithium carbonate salt, the step 7) lithium purification solution is adsorbed and purified with a purification device chelating resin to remove Ca ²⁺ and Mg ²⁺ in the lithium purification solution, and then undergoes a concentration process, It is a lithium deep purification solution, which is processed to prepare battery-grade lithium hydroxide or battery-grade lithium carbonate.

The method for extracting lithium from electrolytic aluminum waste slag by the mixed salt calcination method, its step 1) the ball mill is to control the ball milling time to 2h-3h, and to control the speed of the ball mill to 200r/min-400r/min; at the same time, to control the electrolytic aluminum The mass ratio of waste residue: calcium salt is=100:40-60; the calcium salt is any one or a mixture of calcium oxide, calcium carbonate, and calcium hydroxide.

Preferably, in step 2) pressing, the pressure of the press is controlled at 6000-8000 MPa, the calcination temperature is controlled at 800°C-950°C, and the calcination holding time is 1-2h.

Preferably, step 3) controls the mass ratio of roasting material and potassium salt to be roasting material:potassium salt=100:20-80; the potassium salt is a mixture of potassium sulfate and/or potassium carbonate.

Preferably, it is step 5) alkali leaching treatment, the concentration of the control lye is 0.5-0.7mol/L, and the lye is potassium hydroxide solution or sodium hydroxide solution; the mass ratio of the control roasting fine powder and water is 1: 5.5-6.5; control the leaching temperature during alkali leaching treatment to 90°C-95°C, and control the leaching time to 2h-4h under the condition of constant stirring.

Further, step 6) is to control the number of countercurrent washing of the filter residue at 2-6 times, and control the concentration of lithium ions in the washing residue to be ≤0.20wt%.

A method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method according to the present invention, step 7) freezing treatment, controlling the freezing temperature to -5°C to 5°C, and the freezing time to 2-3h.

Further, it is step 9) deep purification, controlling the concentration of lithium ions in the lithium deep purification solution to 12-18g/L; and controlling the concentration of Ca ²⁺ , Mg ²⁺ , P, F ^- , and ions in the lithium deep purification solution ≤0.06%; and then filtered and separated to prepare battery-grade lithium hydroxide and battery-grade lithium carbonate.

A method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method according to the present invention, wherein the electrolytic aluminum waste slag contains the following components by mass percentage: Al ³⁺ : 12% to 18%, Na ⁺ : 14% ~20%, F ^- : 30% ~ 54%, Li ⁺ : 1.5% ~ 3.2%, SiO ₂ : 0.05% ~ 1.05%, Fe ₂ O ₃ : 0.5% ~ 0.20%, SO ₄ ^2— : 0.11% ~ 0.35%.

In step 6) of the present invention, the filtered filter residue and washing residue can be used as raw materials in the carbon industry.

The method for extracting lithium from electrolytic aluminum waste residue disclosed by the mixed salt calcination method of the present invention involves the main chemical reaction equation: 2Na ₃ AlF ₆ +3CaO=Al ₂ O ₃ +6NaF+3CaF ₂

3CaO+2AlF ₃ ＝Al ₂ O ₃ +3CaF ₂

12CaO+7Al ₂ O ₃ ＝12CaO·7Al ₂ O ₃

CaO+6Al ₂ O ₃ ＝CaO·6Al ₂ O ₃

CaO+2Al ₂ O ₃ =CaO·2Al ₂ O ₃ .

The invention discloses a method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method. The chemical process is as follows: electrolytic aluminum waste slag raw material, crushing, crushing, ball mill ball milling, fine powder pressed into powder brick, tunnel kiln roasting, two The first crushing, the second ball milling to about 80 mesh is the mixture, the second roasting of the mixture, the second crushing, and ball milling are roasted fine powder, alkali leaching treatment, solid-liquid separation and countercurrent washing, freezing, rinsing, and finally deep purification and preparation. Battery grade lithium hydroxide or battery grade lithium carbonate.

A method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method disclosed in the present invention, compared with the prior art and the extraction of lithium by pressure cooking with concentrated sulfuric acid, has a large amount of hydrofluoric acid overflowing, pollutes the environment, and has high energy consumption for equipment, etc. Compared with it, it has the following outstanding advantages:

First, the present invention uses electrolytic aluminum waste slag as raw material and adopts the method of calcining mixed salts. The technical process is simple, the energy consumption cost is low, and the product quality is high. The whole process is a kind of comprehensive utilization of lithium solid waste. There is little hydrofluoric acid solution in the extraction process, which will not cause great pollution to the environment. The second is that in the subsequent leaching and extraction process, the content of other metal impurity ions in the leachate is low, such as impurity Al (g/ L) content, when using sulfuric acid pressure cooking method to extract lithium, is 10.8, and adopts the method of the present invention, and its Al (g/L) 0.5; Fe (mg/L) is 1.80, and the inventive method is 0.1; That is, the mass concentration of Al and Fe in the leach solution is low, which is very beneficial to the subsequent extraction of lithium salt lithium hydroxide or lithium carbonate salt, that is, the method of easy separation and extraction of lithium salt, and realizes the industrialization of lithium extraction technology from electrolytic aluminum waste residue. and applied in large-scale production. The production cost of extracting lithium from electrolytic aluminum waste residue is greatly reduced; the yield of lithium leaching can reach 95%.

Detailed ways:

The present invention will be further described in detail according to specific corresponding examples below, and the components in the present invention can be obtained commercially, in mass ratio or mass parts.

The invention discloses a method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method. The electrolytic aluminum waste slag is used as a raw material, potassium and calcium salts are used as auxiliary materials, and a mixed salt calcination method is adopted. Soaking, solid-liquid separation, freezing to remove impurities, purification process, which includes the following method steps:

1) Crushing and ball milling, the electrolytic aluminum waste slag raw material is mechanically crushed into fine materials, sieved and fully mixed with calcium salt, and then enters the ball milling device for ball milling treatment. The ball milling treatment time is controlled to 2h-3h, and the ball mill is controlled The rotational speed during ball milling is 200r/min-400r/min; at the same time, the mass ratio of electrolytic aluminum waste residue: calcium salt is controlled to be =100:40-60; the calcium salt is any one of calcium oxide, calcium carbonate, and calcium hydroxide A mixture of one or more types; the electrolytic aluminum waste slag contains the following components by mass percentage, that is, the content ratio of the main components: Al ³⁺ : 12% to 18%, Na ⁺ : 14% to 25%, F ^- : 30% to 54%, Li ⁺ : 1.5% to 3.2%, SiO ₂ : 0.05% to 1.05%, Fe ₂ O ₃ : 0.5% to 0.20%, SO ₄ ^2— : 0.11% to 0.35% %; for the ball milling material;

2) Compression, calcification and roasting, step 1) the ball-milled mixture is placed in a press device, and pressed into a brick shape. During the pressing process, the water content in the mixture or the ball-milled mixture is controlled at the same time. That is to control the brick material that can be pressed into a block, and control the pressure of the press to 6000-8000MPa, and then place the block of bricks in the tunnel kiln device for calcification and roasting after stacking, and control the roasting process. The temperature is 800℃～950℃, and the roasting and holding time is 1-2h, which is the roasting material;

3) Secondary ball milling of the ingredients, after stirring and mixing the roasted material and potassium salt in step 2), then place it in a ball milling device for full mixing and ball milling to 50-100 mesh, and control the mass ratio of the roasted material and potassium salt to be the roasted material : potassium salt=100:20-80; the potassium salt is a mixture of potassium sulfate and/or potassium carbonate; after ball milling, it is a mixture;

4) Secondary roasting, put the mixed material in the rotary kiln device, and roast it through the rotary kiln. The clinker is mechanically crushed and then ball milled to 80 mesh to 160 mesh, which is roasted fine powder;

5) Alkali leaching treatment, the roasted fine powder material, lye and aqueous solution are placed in a stirring device, fully stirred and mixed, and leaching is performed, and the concentration of the lye is controlled to be 0.5-0.7mol/L, and the lye is hydrogen Potassium oxide solution or sodium hydroxide solution; control the mass ratio of roasted fine powder and water to 1:5.5-6.5; control the leaching temperature during alkali leaching treatment to 90 ° C ~ 95 ° C, and control the leaching under the condition of constant stirring. The time is 2h-4h; thus, the lithium in the roasted fine powder in the alkaline leaching treatment process exists in the leachate in the form of lithium hydroxide, and the leachate containing lithium hydroxide solution is obtained;

6) Solid-liquid separation and countercurrent washing, the lithium hydroxide solution leachate obtained in step 5) is subjected to solid-liquid separation through a filter device to obtain filter residue and filtrate; the filter residue is subjected to countercurrent washing for 2-6 times, and then plate and frame filter Filtration treatment to obtain washing liquid and washing residue, and control the concentration of lithium ions in the washing residue to ≤0.20wt%;

7) freeze treatment, fully mix the filtrate and washing liquid prepared in step 6) to be a lithium-making solution, process the lithium-making solution through a freezing process, and freeze the potassium, aluminum, etc. in the solution to be mixed with potassium aluminum sulfate dodecahydrate Salt, control the freezing temperature -5°C to 5°C, freeze for 2-3 hours, and then centrifuge to obtain lithium purification solution;

8) Rinsing treatment, the aluminum sulfate potassium salt dodecahydrate obtained after step 7) centrifugation, is continuously rinsed several times with clear water, and the washing liquid and the washing aluminum sulfate potassium salt dodecahydrate are obtained, and washing is the next step 5) use of alkaline leaching treatment;

9) In-depth purification to produce lithium hydroxide or lithium carbonate salt, the step 7) lithium purification solution is adsorbed and purified with a purification device chelating resin to remove Ca ²⁺ and Mg ²⁺ in the lithium purification solution, and then undergoes a concentration process, It is a lithium deep purification solution, and the purification is to control the concentration of lithium ions in the lithium deep purification solution to 12-18g/L; and to control the Ca ²⁺ , Mg ²⁺ , P, F ^- , ions in the purified lithium deep purification solution The mass concentration is less than or equal to 0.06%; and then filtered and separated to prepare raw materials for battery-grade lithium hydroxide and battery-grade lithium carbonate, and further prepared to be battery-grade lithium hydroxide or battery-grade lithium carbonate.

Step 6) The prepared filter residue and washing residue can be used as raw materials for carbon industry production, and the lithium leaching yield can reach 95%. The parts that are not described in the following specific examples are the same as this specific embodiment.

Example 1

The following technical content is further described through specific examples, but the skilled person should be aware that the examples do not limit the protection scope of the patent of the present invention in any way. Modifications or equivalent substitutions made by those skilled in the art on this basis shall be included within the protection scope of this patent.

A method for extracting lithium from electrolytic aluminum waste slag by a mixed salt calcination method disclosed in the embodiment of the present invention uses the electrolytic aluminum waste slag from an aluminum company in Tianshan, Xinjiang as the raw material of this example, and its main components are as shown in the following table 1 .

Table 1,

Wt(F) Wt(Na) Wt(Al) Wt(Ca) Wt(Li) Wt (Other) 53.10 24.89 12.73 1.90 2.12 3.75

Note: The contents of each component in the table are mass ratios.

The raw material electrolytic aluminum waste slag is mechanically crushed into subdivided materials, after sieving, a certain amount of calcium oxide is added, it is put into a ball mill for grinding for 2 hours, and the speed is 250r/min, and it is fully stirred and mixed to form a mixed material or called a ball milled homogeneous material; control electrolytic aluminum The mass ratio of waste slag: calcium oxide is = 100:40; the fine powder material that is ground is the ball milling mix, the humidity of the ball milling mix is controlled, and then pressed into bricks with a press device, that is, bricks, controlled The pressure of the press is 6000-8000MPa, and then the bricks are stacked so that they can enter the tunnel kiln device for roasting, and the tunnel kiln is controlled for calcification and high-temperature roasting transformation. The roasting temperature is controlled at 900 ° C ~ 950 ° C, and the roasting holding time is 1 -2h; the clinker after calcification and roasting is the roasting material; then put it in a ball milling device for ball milling to 70 mesh, the fine powder is the roasting material, according to the fine powder: potassium sulfate: potassium carbonate = 100:30:10 (mass ratio) ingredients; the uniformly mixed material is the mixture, the mixture is roasted in a rotary kiln, the roasting temperature of the rotary kiln is controlled at 880°C, the high temperature roasting and holding time is 1h, the powder is processed to 100 mesh, and it is processed into calcined sand and roasted Fine powder: deep alkali leaching or alkali leaching treatment, stir and mix roasted fine powder with 0.6mol/L potassium hydroxide solution and water, control the mass ratio of clinker roasted fine powder and water to 1:6, and leaching The temperature is 90 ℃ ~ 95 ℃, the stirring and leaching time is 4 hours, so that the lithium in the clinker fine powder, that is, the roasted fine powder, enters the leaching liquid as lithium lithium hydroxide liquid; solid-liquid separation and countercurrent washing, the lithium lithium hydroxide The solid-liquid mixture of the solution passes through the filter device for solid-liquid separation to obtain filter residue and filtrate. Carry out countercurrent washing to the filter residue 4 times, the filter device is a plate and frame filter, control the concentration of lithium ions in the filter residue ≤ 0.20wt%; make lithium purification solution, mix the above-mentioned filtrate and washing liquid to make lithium solution, and use freezing process Potassium, sodium, and aluminum in the solution are formed into potassium aluminum sulfate dodecahydrate mixed salt, and the lithium purification solution is prepared by centrifugation; the freezing temperature is controlled at -5°C to 5°C, and the freezing time is 2-3h; the dodecahydrate after centrifugation The aluminum sulfate potassium salt is washed twice, and the obtained washing liquid, namely the flushing liquid, is stored for the next alkali leaching; the lithium purification liquid is then adsorbed and purified by chelating resin to treat Ca ²⁺ and Mg ²⁺ , and after the concentration process, it becomes a concentrated liquid The concentration of lithium ions is about 15g/L, which is the lithium deep purification solution. Control the concentration of Ca ²⁺ , Mg ²⁺ , P, F ^- , and ions in the purified solution, that is, the lithium deep purification solution, to ≤0.06%, and filter Separation; be the solution that is used to prepare battery-grade lithium hydroxide or lithium carbonate, obtain battery-grade lithium hydroxide or lithium carbonate through further preparation, the battery-grade lithium hydroxide or lithium carbonate product detection result that embodiment case 1 prepares See Table 2 below.

The parts not described in the following examples are all the same as those in Example 1 or the specific implementation.

Example 2

This example is based on the electrolytic aluminum waste slag of a Dongfang Hope aluminum company as raw material, mechanically crushing the electrolytic aluminum waste slag of a Dongfang Hope aluminum company into subdivided materials, and adding a certain amount of calcium oxide and calcium hydroxide after sieving. Mix in any proportion, enter the ball mill to grind for 3 hours, the speed is 280r/min, fully mix the materials evenly; the mixture of electrolytic aluminum waste residue: calcium oxide and calcium hydroxide = 100:45 (mass ratio); press the ground fine powder into Bricks, tunnel kiln calcification high-temperature roasting transition, control temperature 900 ° C, high-temperature roasting holding time is 2 hours; clinker after calcification roasting, ball mill to 70 mesh, according to the fine powder: potassium sulfate: potassium carbonate = 100: 40: 10 (mass ratio) ingredients. The uniformly mixed material is roasted in a rotary kiln at a controlled temperature of 880°C, held at high temperature for 1 hour, milled to 100 mesh, and processed into calcined crushed fine powder; deep alkali leaching, the roasted fine powder and 0.6mol/L Potassium hydroxide solution is stirred and mixed, the mass ratio of clinker fine powder and water is controlled to be 1:6, the leaching temperature is 90°C, and the stirring and leaching time is 4 hours, so that the lithium in the clinker fine powder enters as lithium hydroxide liquid into the leaching liquid; solid-liquid separation and countercurrent washing, the solid-liquid mixture of lithium hydroxide solution is passed through a filter device for solid-liquid separation to obtain filter residue and filtrate. Carry out countercurrent washing to filter residue 4 times, filter device is a plate-and-frame filter, control lithium ion concentration 0.150wt% in filter residue; Make lithium purification solution, mix the above-mentioned filtrate and washing liquid together to make lithium solution, freeze process Potassium, sodium and aluminum in the solution form a mixed salt of potassium aluminum sulfate dodecahydrate, and the lithium purification solution is produced by centrifugal separation. Freezing temperature -5 ℃ ~ 5 ℃, freezing time 3h. The potassium aluminum sulfate dodecahydrate after centrifugation is washed twice, and the washing solution is stored for the next alkali leaching; the lithium purification solution is then adsorbed and purified by chelating resin to treat Ca ²⁺ and Mg ²⁺ , and after the concentration process, it is concentrated The concentration of lithium ions in the liquid is about 17g/L, and the concentration of Ca ²⁺ , Mg ²⁺ , P, F ^- in the purified solution is controlled to 0.05% by filtration and separation to prepare battery-grade lithium hydroxide and battery-grade lithium carbonate . The quality index of battery-grade lithium carbonate is used below, and its analysis report is tested by relevant departments, as shown in Table 2 below.

Table 2:

Product Name: Battery Grade Lithium Carbonate,

Product appearance: fine powder, white powder, no agglomeration,

Particle size: The particle size diameter of D50 is used as the test data, and the standard is controlled at about 6 μm.

Explanation: It can be seen from the result report sheet of the above detection that the technological route disclosed by the present invention can realize industrialization and industrialization. The prepared lithium hydroxide has a content of more than 99.5%, and the test results all meet the quality standard requirements of battery-grade lithium carbonate.

comparative example

In this comparative example, the raw materials used are the same as those in the examples, and the electrolytic aluminum waste slag is extracted by the current general sulfuric acid method; The electrolytic aluminum waste slag of an aluminum company in Henan was reacted with concentrated sulfuric acid at 200-400°C for 2-3 hours to obtain a mixture of sulfates containing sodium, aluminum and lithium. The hydrogen fluoride gas generated by the reaction was absorbed by water to obtain hydrofluoric acid in water② Dissolve the sulfate mixture containing sodium, aluminum and lithium in water to prepare a solution with a concentration of 25% to 35% and filter to remove unreacted carbon residue. ③Add sodium carbonate to the above filtrate and carry out alkaline hydrolysis reaction at 20-40°C to obtain hydrogen respectively. Aluminum Oxide and Lithium Carbonate ④ Add Lithium Carbonate Precipitation to Decarburization Mother Liquor to Prepare Slurry. It is advisable to add water to prepare 3%~4% Lithium Carbonate Slurry, and then introduce _CO2 to carry out carbonization reaction and control the pH value of carbonization end point to 6~6.5 , Filtrate to obtain the lithium bicarbonate solution filter residue for cryolite synthesis; ⑤Heat the lithium bicarbonate solution to 90-100°C for decarburization and recrystallization to obtain battery-grade lithium carbonate. Using the method of the present invention, the electrolytic aluminum waste slag of an aluminum industry in Kaiman, Henan is mechanically crushed into subdivided materials, after sieving, a certain amount of calcium oxide is added, and it is put into a ball mill for grinding for 2.5 hours at a speed of 260r/min, and the materials are fully mixed evenly . Electrolytic aluminum waste slag:calcium oxide=100:47 (mass ratio). The ground fine powder is pressed into bricks by a press, and transformed into calcified high-temperature roasting in a tunnel kiln. The temperature is controlled at 920°C, and the high-temperature roasting holding time is 2 hours. The clinker after calcification and roasting is ball milled to 70 meshes, and the ingredients are mixed according to fine powder: potassium sulfate: potassium carbonate = 100: 42: 10 (mass ratio). The uniformly mixed material is roasted in a rotary kiln, the temperature is controlled at 890°C, the high temperature holding time is 1h, the powder is milled to 100 mesh, and it is processed into calcined and crushed fine powder; deep alkali leaching, the roasted fine powder and 0.6mol/L Potassium hydroxide solution is stirred and mixed, the mass ratio of clinker fine powder and water is controlled to be 1:6, the leaching temperature is 90°C, and the stirring and leaching time is 4 hours, so that the lithium in the clinker fine powder enters as lithium hydroxide liquid into the leaching liquid; solid-liquid separation and countercurrent washing, the solid-liquid mixture of lithium hydroxide solution is passed through a filter device for solid-liquid separation to obtain filter residue and filtrate. Carry out countercurrent washing to filter residue 4 times, filter device is a plate-and-frame filter, control lithium ion concentration 0.150wt% in filter residue; Make lithium purification solution, mix the above-mentioned filtrate and washing liquid together to make lithium solution, freeze process Potassium, sodium and aluminum in the solution form a mixed salt of potassium aluminum sulfate dodecahydrate, and the lithium purification solution is produced by centrifugal separation. Freezing temperature -5 ℃ ~ 5 ℃, freezing time 3h. The potassium aluminum sulfate dodecahydrate after centrifugation is washed twice, and the washing solution is stored for the next alkali leaching; Ca ²⁺ and Mg ²⁺ are treated with chelating resin adsorption and purification, and concentrated liquid lithium ion is obtained through the concentration process. The concentration content is about 17g/L, and the concentration of Ca ²⁺ , Mg ²⁺ , P, F ^- , and ions in the control solution is separated by filtration at 0.05%. Lithium carbonate is prepared by precipitation of lithium with sodium carbonate solution. However, the main difference between the patent of the present invention and the sulfuric acid method is that fluoride ions are stabilized in the slag with calcium fluoride compounds, rather than a large amount of F ions entering the leachate, and other metal ions in the leachate such as iron, aluminum, copper, etc. and fluorine content is extremely low. See Table 3 below, which is also the comparison of the content of the main impurity ions in the leachate in the technical route of the present invention and the comparative examples.

The results of impurity detection and analysis in the leachate are compared as follows, Table 3,

F(g/L) Al(g/L) Fe(mg/L) Si (mg/L) Cu(mg/L) concentrated sulfuric acid method 15.12 10.8 1.80 2.70 0.70 The method of the invention 0.20 0.50 0.10 0.60 0.20

As can be seen from the above test results, the patented method is used for the same raw material, and the mass concentration of impurity ions in the primary leachate is significantly lower than that in the sulfuric acid process; it is a great burden for subsequent deep purification and impurity removal, which shows that this The invented process method can be applied to large-scale industrialized production, and greatly reduces its production cost. And the content of its main impurity ion adopting the method for comparative text embodiment is obviously higher than the method of the present invention.

The description is only an overview of the technical solution of the present invention, and it can be implemented according to the contents of the description. It is only a preferred embodiment of the present invention, and does not limit the present invention in any form. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the above-mentioned technical content to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent embodiment with equivalent changes . Therefore, any changes, modifications, equivalent changes and modifications made to the above embodiments according to the technology of the present invention, which do not deviate from the technical solution of the present invention, all belong to the protection scope of the technical solution.

Claims (5)

1. A method for extracting lithium from electrolytic aluminum waste residue by using a mixed salt calcination method takes the electrolytic aluminum waste residue as a raw material, takes potassium and calcium salts as auxiliary materials, adopts the mixed salt calcination method, and adopts the processes of calcification calcination, potassium salt re-calcination, alkaline leaching, solid-liquid separation, freezing and impurity removal and purification, and is characterized by comprising the following steps:

1) Crushing and ball milling, namely mechanically crushing electrolytic aluminum waste residues into fine materials, sieving, and then enabling the fine materials and calcium salt to enter a ball milling device for ball milling treatment to obtain ball milling mixed materials;

2) Pressing and calcified roasting, namely placing the ball-milling mixed material obtained in the step 1) into a pressing device, pressing into brick blocks, and then placing the brick blocks into a tunnel kiln device for middle calcified roasting to obtain a roasted material;

3) Mixing and ball milling for the second time, and placing the roasting material and potassium salt obtained in the step 2) into a ball milling device for mixed ball milling until the particle size reaches 50-100 meshes, so as to obtain a mixture;

4) The mixture is put into a rotary kiln device for secondary roasting, the roasting temperature is controlled to be 750-900 ℃ and the roasting heat preservation time is 0.5-1.0h, the secondary roasting is carried out, the secondary roasting is mechanically crushed and ball-milled by clinker, and the secondary roasting is processed to 80-160 meshes, thus obtaining roasting fine powder;

5) Alkali leaching, namely placing the calcined fine powder, alkali liquor and aqueous solution into a stirring device, fully stirring and mixing, and leaching to obtain a lithium hydroxide-containing solution leaching solution;

6) Solid-liquid separation and countercurrent washing, wherein the lithium hydroxide solution leaching solution is subjected to solid-liquid separation by a filtering device to obtain filter residues and filtrate; countercurrent washing the filter residue for several times, filtering with a plate-and-frame filter to obtain washing liquid and washing residue, and controlling the concentration of lithium ions in the washing residue to be low;

7) Freezing, namely fully mixing the filtrate prepared in the step 6) with the washing liquid to prepare a lithium preparation solution, performing freezing process treatment on the lithium preparation solution to obtain aluminum potassium sulfate dodecahydrate mixed salt, and performing centrifugal separation treatment to obtain a lithium purification solution;

8) Washing, namely washing the aluminum potassium sulfate dodecahydrate obtained after centrifugal separation in the step 7) with clear water for a plurality of times to obtain a washing liquid and washed aluminum potassium sulfate dodecahydrate, wherein the washing liquid is used for the alkaline leaching treatment of the next step 5);

9) Deeply purifying to prepare hydrogen lithium oxide or lithium carbonate salt, and removing Ca in the lithium purifying liquid by using chelating resin adsorption purification treatment of the purifying liquid obtained in the step 7) by using a purifying device ²⁺ 、Mg ²⁺ Then the lithium deep purification liquid is treated by a concentration process, and is prepared into battery-grade lithium hydroxide or battery-grade lithium carbonate by treatment;

the ball milling step 1) is to control the ball milling time to be 2-3h and the rotating speed of the ball mill to be 200-400 r/min; simultaneously controlling electrolytic aluminum waste residues: the mass ratio of calcium salt is = 100:40-60; the calcium salt is any one or the mixture of more of calcium oxide, calcium carbonate and calcium hydroxide;

step 2) pressing, namely controlling the pressure of the pressing machine to be 6000-8000MPa, controlling the roasting temperature to be 800-950 ℃ and the roasting heat preservation time to be 1-2h;

and 3) controlling the mass ratio of the roasting material to the potassium salt to be as follows: potassium salt = 100:20-80 parts; the potassium salt is a mixture of potassium sulfate and/or potassium carbonate.

Step 5), alkaline leaching treatment, wherein the concentration of alkaline liquor is controlled to be 0.5-0.7mol/L, and the alkaline liquor is potassium hydroxide solution or sodium hydroxide solution; the mass ratio of the calcined fine powder to the water is controlled to be 1:5.5-6.5; the leaching temperature is controlled to be 90-95 ℃ during alkaline leaching treatment, and the leaching time is controlled to be 2-4 h under the condition of continuous stirring.

2. The method for extracting lithium from electrolytic aluminum waste residue by using a mixed salt calcination method according to claim 1, wherein the step 6) is to control the countercurrent washing times of the filter residue to be 2-6 times, and the concentration of lithium ions in the washing residue to be less than or equal to 0.20wt%.

3. The method for extracting lithium from electrolytic aluminum waste residue by using a mixed salt calcination method according to claim 1, wherein 7) the freezing treatment is performed, the freezing temperature is controlled to be-5 ℃ to 5 ℃, and the freezing time is controlled to be 2 to 3 hours.

4. The method for extracting lithium from electrolytic aluminum waste residue by using a mixed salt calcination method according to claim 1, wherein the step 9) is deep purification, and the concentration content of lithium ions in the lithium deep purification liquid is controlled to be 12-18g/L; and control Ca in the lithium deep purification liquid ²⁺ 、Mg ²⁺ 、P、F ^- Ion mass concentration is less than or equal to 0.06%; and then filtering and separating to prepare the battery-grade lithium hydroxide and the battery-grade lithium carbonate.

5. The method for extracting lithium from electrolytic aluminum waste residues by using the mixed salt calcination method as claimed in claim 1, wherein the electrolytic aluminum waste residues comprise the following components in percentage by mass: al (Al) ³⁺ ：12％～18％，Na ⁺ ：14％～25％，F ^- ：30％～54％，Li ⁺ ：1.5％～3.2％，SiO ₂ ：0.05％～1.05％，Fe ₂ O ₃ ：0.5％～0.20％，SO ₄ ^2— ：0.11％～0.35％。