Method for preparing hard carbon negative electrode material raw material from bituminous coal

Abstract

The application discloses a method for preparing hard carbon negative material raw materials from bituminous coal, and the method comprises the following steps: removing ash from bituminous coal by the processes of crushing, alkali leaching, alkali leaching activation, centrifugal water washing and acid leaching to prepare hard carbon negative material raw materials; and the generated ash-removing liquid is subjected to silicon and aluminum separation and alkali recovery by a silicon and aluminum separation process, so that the bituminous coal is used in the field of sodium ion battery hard carbon negative material preparation, and valuable components such as silicon and aluminum are separated and extracted, the high-value resource utilization of the bituminous coal is realized, and the low-cost preparation of the sodium battery negative material is facilitated. The application has the characteristics of comprehensive utilization of valuable components and low cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource utilization, and in particular to a method for preparing hard carbon negative material raw materials from bituminous coal. BACKGROUND

[0002] Bituminous coal, as a form of coal, mainly embodies its energy properties. With the further implementation of policies, the use of coal and its application scenarios are shrinking, and it is urgent to explore high-value material utilization scenarios for bituminous coal. Sodium-ion battery negative materials mainly use hard carbon materials, which are key components of sodium-ion batteries and directly affect the performance of sodium-ion batteries. If bituminous coal is used to prepare sodium-ion battery negative materials, it will not only realize the high-value utilization of bituminous coal, but also provide a new raw material solution for hard carbon negative materials of sodium-ion batteries.

[0003] Chinese patent CN119695152A discloses a coal-based hard carbon negative material and a preparation method thereof. The coal-based hard carbon negative material is prepared by acid treatment, pre-carbonization, and steam activation. The first efficiency of the hard carbon negative material prepared by the method can reach 80% or more than 83%, but the long process and strict raw material requirements limit its subsequent development. Chinese patent CN119683603A discloses a method for preparing a coal-based hard carbon negative material using a coal-based material as a raw material. The method comprises the steps of crushing, acid washing to remove ash, pre-carbonization, and steam activation. The acid washing process uses hydrochloric acid, hydrofluoric acid, and nitric acid in combination, which is dangerous and polluting, and poses a challenge to large-scale production. Chinese patent CN118545697A discloses a hard carbon negative material and a preparation method and application thereof. The ash removal is achieved by acid washing, which inevitably causes waste of valuable components in the ash. Therefore, if bituminous coal is used to prepare hard carbon negative materials for sodium-ion batteries, the process can be simplified, valuable components can be recovered and utilized, the high-value material utilization of bituminous coal can be further realized, the cost of preparing hard carbon negative materials can be reduced, and conditions for subsequent large-scale production can be created. SUMMARY

[0004] The application aims to provide a method for preparing hard carbon negative material raw materials from bituminous coal. The method comprises the steps of crushing, alkali leaching, alkali leaching activation, centrifugal washing, and acid leaching to prepare hard carbon negative materials for sodium-ion batteries from bituminous coal. The method not only realizes the high-value material utilization of bituminous coal, but also recovers valuable components such as silicon and aluminum. It is a low-cost and environmentally friendly method for preparing hard carbon negative material raw materials from bituminous coal.

[0005] To achieve the above-mentioned purposes, the application adopts the following technical solutions:

[0006] The application provides a method for preparing hard carbon negative material raw materials from bituminous coal.

[0007] In the above technical scheme, the specific method comprises the following steps:

[0008] Step (1), crushing: the bituminous coal is placed in a crusher to obtain bituminous coal powder;

[0009] Step (2), alkali leaching: the sodium hydroxide solution and the bituminous coal powder obtained in step (1) are placed in a high-pressure reaction kettle and then reacted in a homogeneous reactor, and the solid is filtered to obtain alkali leaching residue;

[0010] Step (3), alkali leaching activation: the sodium hydroxide solution and the alkali leaching residue obtained in step (2) are placed in a high-pressure reaction kettle and then reacted in a homogeneous reactor, and the solid is filtered to obtain alkali leaching activated carbon;

[0011] Step (4), centrifugal water washing: the alkali leaching activated carbon obtained in step (3) is placed in a centrifuge, and then the pH value is adjusted to neutral by adding sulfuric acid or hydrochloric acid solution for water washing to obtain washing residue;

[0012] Step (5), acid leaching: the sulfuric acid or hydrochloric acid solution and the washing residue obtained in step (4) are placed in a magnetic stirrer for reaction to obtain hard carbon negative material raw materials;

[0013] Step (6), silicon precipitation: the ash-removing liquid obtained in step (2) is subjected to a silicon precipitation process to obtain a crude silicon product, and the alkali washing liquid can be reused in the alkali leaching process of step (2);

[0014] Step (7), aluminum precipitation: the secondary ash-removing liquid obtained in step (3) is subjected to an aluminum precipitation process to obtain a crude aluminum product, and the secondary alkali washing liquid can be reused in the alkali leaching activation process of step (3).

[0015] In the above technical scheme, step (1) adopts a dry grinding mode, and the particle size of the obtained bituminous coal powder is not less than 100 mesh.

[0016] In the above technical scheme, in step (2), the concentration of the sodium hydroxide solution is 160-320 g / L, the mass ratio of the sodium hydroxide solution to the bituminous coal powder is (8-15):1, the rotation speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 85-120 DEG C, and the reaction time is 60-180 min.

[0017] In the above technical solution, in step (3), the concentration of the sodium hydroxide solution is 240-400 g / L, the mass ratio of the sodium hydroxide solution to the alkaline leaching residue is (8-15):1, the speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 200-280°C, and the reaction time is 60-180 min.

[0018] In the above technical solution, in step (4), the centrifuge speed is 5000-15000 r / min, the water washing time is 5-15 min each time, the liquid-to-solid ratio of each water washing is (20-50):1, and the ultrapure water washing is repeated 3 times.

[0019] In the above technical solution, in step (5), the concentration of the sulfuric acid or hydrochloric acid solution is 20-30%, the temperature in the magnetic stirrer is 45-85°C, the mass ratio of the sulfuric acid or hydrochloric acid solution to the washed slag is (20-50):1, the reaction time is 8-15h, and after the reaction is completed, the washing liquid is washed with water until the pH value is neutral to obtain the hard carbon negative electrode material raw material.

[0020] The beneficial effects of this invention are: it achieves high-value utilization of bituminous coal in the preparation of hard carbon anode materials for sodium-ion batteries, while also enabling the separation and extraction of valuable components such as silicon and aluminum. This paves the way for high-value resource utilization of bituminous coal and creates conditions for the low-cost preparation of sodium battery anode materials. This invention boasts comprehensive utilization of valuable components and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the method for preparing hard carbon negative electrode material raw material from bituminous coal of the present invention. DETAILED DESCRIPTION

[0022] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments. The present invention can be implemented in many different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concept of the present invention to those skilled in the art. The present invention will be limited only by the claims.

[0023] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0024] This invention uses bituminous coal as the main raw material and removes ash from the coal through crushing, alkali leaching, alkali leaching activation, centrifugal water washing, and acid leaching. It also recovers silicon and aluminum through silicon and aluminum precipitation processes, and reuses the acid and alkali. The main technical solutions are as follows:

[0025] (1) Pulverization: pulverize the bituminous coal in a pulverizer by dry grinding to obtain a bituminous coal powder with a particle size of no less than 100 mesh.

[0026] (2) Alkali leaching: place the sodium hydroxide alkali solution and the bituminous coal powder obtained in step (1) in a high-pressure reaction kettle and then in a homogeneous reactor to react, wherein the concentration of sodium hydroxide is 160-320 g / L, the liquid-solid ratio is (8-15):1, the rotation speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 85-120 ℃, and the reaction time is 60-180 min; filter the solid to obtain alkali leaching residue.

[0027] (3) Alkali leaching activation: place the sodium hydroxide alkali solution and the alkali leaching residue obtained in step (2) in a high-pressure reaction kettle and then in a homogeneous reactor to react, wherein the concentration of sodium hydroxide is 240-400 g / L, the liquid-solid ratio is (8-15):1, the rotation speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 200-280 ℃, and the reaction time is 60-180 min; filter the solid to obtain alkali leaching activated carbon.

[0028] (4) Centrifugal water washing: place the alkali leaching activated carbon obtained in step (3) in a centrifuge, adjust the pH value to neutral by adding sulfuric acid or hydrochloric acid, and then wash with water, wherein the rotation speed of the centrifuge is 5000-15000 r / min, the water washing time is 5-15 min each time, the liquid-solid ratio is (20-50):1, and after the first neutral pH adjustment and centrifugal water washing, repeat the ultrapure water washing for 3 times to obtain washing residue.

[0029] (5) Acid leaching: place the acid solution and the washing residue obtained in step (4) in a magnetic stirrer to react, wherein the acid solution is one of sulfuric acid or hydrochloric acid, the concentration is 20-30%, the temperature is 45-85 ℃, the liquid-solid ratio is (20-50):1, and the acid washing time is 8-15 h; after acid washing, repeat water washing until the pH of the washing liquid is neutral; adjust the concentration of the acid washing liquid to reuse the acid washing process, and finally obtain the hard carbon negative electrode material raw material.

[0030] (6) Silicon precipitation: obtain crude silicon product by silicon precipitation process from the ash removal liquid obtained in step (2), and the alkali washing liquid can be reused in the alkali leaching process.

[0031] The silicon precipitation process specifically includes: introducing carbon dioxide into the ash removal liquid, and reacting the carbon dioxide with sodium silicate to produce silicic acid, thereby realizing the precipitation of silicon.

[0032] (7) Aluminum precipitation: obtain crude aluminum product by aluminum precipitation process from the secondary ash removal liquid obtained in step (3), and the secondary alkali washing liquid can be reused in the alkali leaching activation process.

[0033] There are two types of aluminum precipitation processes: carbonization and seeding. The present invention utilizes both processes to achieve aluminum precipitation. The carbonization process involves introducing carbon dioxide into the secondary deashing solution, causing sodium metaaluminate to react with carbonic acid to form aluminum hydroxide precipitate. The seeding process involves adding aluminum hydroxide seeds to the secondary desiliconization solution to promote the growth of aluminum hydroxide crystals, resulting in aluminum hydroxide precipitate.

[0034] Example 1

[0035] Using bituminous coal as raw material, the ash content in the bituminous coal is removed through crushing, alkali leaching, alkali leaching activation, centrifugal water washing, and acid leaching. At the same time, silicon and aluminum are recovered through silicon precipitation and aluminum precipitation processes, and the acid and alkali are reused. The main technical solutions are as follows:

[0036] (1) Crushing: Place the bituminous coal in a crusher and use dry grinding to obtain bituminous coal powder with a particle size that can pass through a 100-mesh sieve.

[0037] (2) Alkali leaching: sodium hydroxide alkaline solution and the bituminous coal powder obtained in step (1) are placed in a high-pressure reactor and reacted in a homogeneous reactor, wherein the sodium hydroxide concentration is 160 g / L, the liquid-solid ratio is 12:1, the speed of the homogeneous reactor is 50 r / min, the reaction temperature is 115 °C, and the reaction time is 60 min. The solid is filtered to obtain the alkaline leaching residue.

[0038] (3) Alkali leaching activation: The sodium hydroxide alkaline solution and the alkaline leaching residue obtained in step (2) are placed in a high-pressure reactor and reacted in a homogeneous reactor, wherein the sodium hydroxide concentration is 320 g / L, the liquid-solid ratio is 12:1, the speed of the homogeneous reactor is 50 r / min, the reaction temperature is 220 °C, and the reaction time is 120 min. The solid is filtered to obtain alkali-leached activated carbon.

[0039] (4) Centrifugal water washing: The alkali-leached activated carbon obtained in step (3) is placed in a centrifuge, sulfuric acid is added to adjust the pH value to neutral, and then washed with water. The centrifuge speed is 10,000 r / min, the water washing time is 10 min each time, and the liquid-solid ratio is 40:1. After the first centrifugal water washing to adjust the pH to neutral, repeat the ultrapure water washing three times to obtain washed residue.

[0040] (5) Pickling: sulfuric acid and the slag obtained in step (4) are placed in a magnetic stirrer for reaction. The concentration of sulfuric acid is 20%, the temperature is 65 °C, the liquid-solid ratio is 35:1, and the pickling time is 10 h. After pickling, water washing is repeated until the pH of the washing solution is neutral. After adjusting the concentration of the pickling solution, it can be reused in the pickling process to finally obtain the raw material of the hard carbon negative electrode material.

[0041] (6) Silicon precipitation: The deashing liquid obtained in step (2) is subjected to a silicon precipitation process to obtain a crude silicon product, and the alkaline washing liquid can be reused in the alkaline leaching process.

[0042] (7) Aluminum precipitation: the secondary deashing liquid obtained in step (3) is subjected to aluminum precipitation process to obtain crude aluminum product, and the secondary alkali washing liquid can be reused in the alkali leaching activation process.

[0043] The hard carbon negative electrode material raw material obtained in step (5) is made into a hard carbon negative electrode material by the method of Chinese invention patent CN118545697A "Hard carbon negative electrode material and its preparation method and application", and a sodium ion battery is assembled. The "hard carbon negative electrode material raw material" in the present application is equivalent to "deashed activated carbon" in patent CN118545697A. The hard carbon negative electrode material is prepared by the method of Example 1 in patent CN118545697A. Then, according to the method described in paragraph

[0089] of patent CN118545697A, a slurry is prepared in a proportion of 8:1:1 of hard carbon negative electrode material, small particle conductive carbon black (Super P) and sodium alginate, and uniformly coated on a copper foil. After drying, the pole piece with a diameter of 14 mm is cut, and the metal sodium is used as the opposite electrode. After assembling into a button cell in a glove box, constant current charge and discharge test is carried out, and the voltage interval is 0 2.5V and the current is 20mAg -1 . The test results are as follows: the charge specific capacity of the obtained sodium ion battery is 294.0 mAh / g, the discharge specific capacity is 337.3mAh / g, and the initial efficiency is 87.16%.

[0044] Example 2

[0045] With bituminous coal as raw material, the removal of ash in bituminous coal is realized by the methods of crushing, alkali leaching, alkali leaching activation, centrifugal washing, and acid leaching. At the same time, the recovery of silicon and aluminum is realized by silicon precipitation and aluminum precipitation processes, and the reuse of acid and alkali is realized. The main technical scheme is as follows:

[0046] (1) Crushing: the bituminous coal is placed in a crusher, and dry grinding is adopted to obtain bituminous coal powder with a particle size that can pass through a 100 mesh screen.

[0047] (2) Alkali leaching: the sodium hydroxide alkali solution and the bituminous coal powder obtained in step (1) are placed in a high-pressure reaction kettle and then reacted in a homogeneous reactor. The concentration of sodium hydroxide is 200 g / L, the liquid-solid ratio is 10:1, the rotation speed of the homogeneous reactor is 100r / min, the reaction temperature is 120℃, and the reaction time is 90 min. The solid is filtered to obtain alkali leaching residue.

[0048] (3) Alkali leaching activation: the sodium hydroxide alkali solution and the alkali leaching residue obtained in step (2) are placed in a high-pressure reaction kettle and then reacted in a homogeneous reactor. The concentration of sodium hydroxide is 400 g / L, the liquid-solid ratio is 15:1, the rotation speed of the homogeneous reactor is 100r / min, the reaction temperature is 260℃, and the reaction time is 180 min. The solid is filtered to obtain alkali leaching activated carbon.

[0049] (4) Centrifugal washing: the alkali-activated carbon obtained in step (3) is placed in a centrifuge, and after adjusting the pH value to neutral with sulfuric acid, it is washed with water. The centrifuge speed is 15000 r / min, the washing time is 15 min, and the liquid-solid ratio is 50:1. After the first neutral pH adjustment and centrifugal washing, the washing residue is washed with ultrapure water for 3 times, and the washing residue is obtained.

[0050] (5) Acid washing: sulfuric acid and the washing residue obtained in step (4) are placed in a magnetic stirrer for reaction. The concentration of sulfuric acid is 30%, the temperature is 85 ℃, the liquid-solid ratio is 50:1, and the acid washing time is 15 h. After acid washing, the washing liquid is adjusted to neutral pH, and the acid washing process can be reused. Finally, the hard carbon negative material raw material is obtained.

[0051] (6) Silicon precipitation: the deashing liquid obtained in step (2) is subjected to a silicon precipitation process to obtain a crude silicon product. The alkali washing liquid can be reused in the alkali leaching process.

[0052] (7) Aluminum precipitation: the secondary deashing liquid obtained in step (3) is subjected to an aluminum precipitation process to obtain a crude aluminum product. The secondary alkali washing liquid can be reused in the alkali leaching activation process.

[0053] The hard carbon negative material raw material obtained is made into a hard carbon negative material by the method described in Chinese invention patent CN118545697A "Hard Carbon Negative Material and Its Preparation Method and Application". The specific method is as described in Example 1. The obtained sodium ion battery has a charge specific capacity of 302.7 mAh / g, a discharge specific capacity of 339.7 mAh / g, and a first efficiency of 89.11%.

[0054] Example 3

[0055] With bituminous coal as raw material, the removal of ash in bituminous coal is realized by the methods of crushing, alkali leaching, alkali leaching activation, centrifugal washing, and acid leaching. At the same time, the recovery of silicon and aluminum is realized by the processes of silicon precipitation and aluminum precipitation, and the reuse of acid and alkali is realized. The main technical scheme is as follows:

[0056] (1) Crushing: the bituminous coal is placed in a crusher, and dry grinding is adopted to obtain bituminous coal powder with a particle size that can pass through a 200 mesh screen.

[0057] (2) Alkali leaching: sodium hydroxide solution and the bituminous coal powder obtained in step (1) are placed in a high-pressure reaction kettle and reacted in a homogeneous reactor. The concentration of sodium hydroxide is 320 g / L, the liquid-solid ratio is 10:1, the rotation speed of the homogeneous reactor is 20 r / min, the reaction temperature is 105 ℃, and the reaction time is 90 min. After filtration, the alkali leaching residue is obtained.

[0058] (3) Alkali leaching activation: The sodium hydroxide alkaline solution and the alkaline leaching residue obtained in step (2) are placed in a high-pressure reactor and reacted in a homogeneous reactor, wherein the sodium hydroxide concentration is 400 g / L, the liquid-solid ratio is 10:1, the speed of the homogeneous reactor is 20 r / min, the reaction temperature is 220 °C, and the reaction time is 120 min. The solid is filtered to obtain alkali-leached activated carbon.

[0059] (4) Centrifugal water washing: The alkali-leached activated carbon obtained in step (3) is placed in a centrifuge, hydrochloric acid is added to adjust the pH value to neutral, and then washed with water. The centrifuge speed is 5000 r / min, the washing time is 10 min, and the liquid-solid ratio is 40:1. After the first centrifugal water washing to adjust the pH to neutral, repeat the ultrapure water washing three times to obtain washed residue.

[0060] (5) Pickling: Place hydrochloric acid and the slag obtained in step (4) in a magnetic stirrer for reaction. The concentration of hydrochloric acid is 20%, the temperature is 55 °C, the liquid-solid ratio is 30:1, and the pickling time is 8 h. After pickling, repeat water washing until the pH of the washing liquid is neutral. After adjusting the concentration of the pickling liquid, it can be reused in the pickling process to finally obtain the raw material of the hard carbon negative electrode material.

[0061] (6) Silicon precipitation: The deashing liquid obtained in step (2) is subjected to a silicon precipitation process to obtain a crude silicon product, and the alkaline washing liquid can be reused in the alkaline leaching process.

[0062] (7) Aluminum precipitation: The secondary deashing liquid obtained in step (3) is subjected to an aluminum precipitation process to obtain a crude aluminum product. The secondary alkaline washing liquid can be reused in the alkaline leaching activation process.

[0063] The obtained hard carbon anode material raw material was prepared into a hard carbon anode material using the method described in Chinese invention patent CN118545697A, "Hard Carbon Anode Material, Preparation Method, and Application thereof," and then assembled to obtain a sodium ion battery, as described in Example 1. The resulting sodium ion battery had a charge capacity of 294.5 mAh / g, a discharge capacity of 354.0 mAh / g, and an initial efficiency of 83.19%.

[0064] Example 4

[0065] Using bituminous coal as raw material, the ash content in the bituminous coal is removed through crushing, alkali leaching, alkali leaching activation, centrifugal water washing, and acid leaching. At the same time, silicon and aluminum are recovered through silicon precipitation and aluminum precipitation processes, and the acid and alkali are reused. The main technical solutions are as follows:

[0066] (1) Crushing: Place the bituminous coal in a crusher and use dry grinding to obtain bituminous coal powder with a particle size that can pass through a 100-mesh sieve.

[0067] (2) Alkali leaching: Put the sodium hydroxide alkali solution and the pulverized bituminous coal obtained in step (1) into a high-pressure reaction kettle and then into a homogeneous reactor for reaction, wherein the concentration of sodium hydroxide is 160 g / L, the liquid-solid ratio is 8:1, the rotation speed of the homogeneous reactor is 20 r / min, the reaction temperature is 85 ℃, and the reaction time is 60 min. After filtration of the solid, alkali leaching residue is obtained.

[0068] (3) Alkali leaching activation: Put the sodium hydroxide alkali solution and the alkali leaching residue obtained in step (2) into a high-pressure reaction kettle and then into a homogeneous reactor for reaction, wherein the concentration of sodium hydroxide is 240 g / L, the liquid-solid ratio is 8:1, the rotation speed of the homogeneous reactor is 20 r / min, the reaction temperature is 240 ℃, and the reaction time is 60 min. After filtration of the solid, alkali leaching activated carbon is obtained.

[0069] (4) Centrifugal water washing: Put the alkali leaching activated carbon obtained in step (3) into a centrifuge, adjust the pH value to neutral by adding hydrochloric acid, and then wash with water. The rotation speed of the centrifuge is 5000 r / min, the water washing time is 5 min, the liquid-solid ratio is 20:1, and after the first neutral pH adjustment and centrifugal water washing, repeat the ultrapure water washing for 3 times to obtain washing residue.

[0070] (5) Acid washing: Put the hydrochloric acid and the washing residue obtained in step (4) into a magnetic stirrer for reaction. The concentration of the hydrochloric acid is 20%, the temperature is 45 ℃, the liquid-solid ratio is 20:1, and the acid washing time is 8 h. After acid washing, repeat the water washing until the pH value of the washing liquid is neutral. Adjust the concentration of the acid washing liquid to reuse it in the acid washing process, and finally obtain the hard carbon negative electrode material raw material.

[0071] (6) Silicon precipitation: Obtain crude silicon product by silicon precipitation process from the ash removal liquid obtained in step (2). The alkali washing liquid can be reused in the alkali leaching process.

[0072] (7) Aluminum precipitation: Obtain crude aluminum product by aluminum precipitation process from the secondary ash removal liquid obtained in step (3). The secondary alkali washing liquid can be reused in the alkali leaching activation process.

[0073] Use the method described in Chinese invention patent CN118545697A "Hard carbon negative electrode material and its preparation method and application" to make the obtained hard carbon negative electrode material into a hard carbon negative electrode material, and assemble a sodium ion battery. The specific method is described in Example 1. The obtained sodium ion battery has a charge specific capacity of 289.6 mAh / g, a discharge specific capacity of 338.3 mAh / g, and a first efficiency of 85.60%.

[0074] Example 5

[0075] Take bituminous coal as raw material, and realize the removal of ash in bituminous coal by the methods of crushing, alkali leaching, alkali leaching activation, centrifugal water washing, and acid leaching. At the same time, realize the recovery of silicon and aluminum by silicon precipitation and aluminum precipitation processes, and realize the reuse of acid and alkali. The main technical scheme is as follows:

[0076] (1) Crushing: Place the bituminous coal in a crusher and use dry grinding to obtain bituminous coal powder with a particle size that can pass through a 200-mesh sieve.

[0077] (2) Alkali leaching: sodium hydroxide alkaline solution and the bituminous coal powder obtained in step (1) are placed in a high-pressure reactor and reacted in a homogeneous reactor, wherein the sodium hydroxide concentration is 320 g / L, the liquid-solid ratio is 15:1, the speed of the homogeneous reactor is 100 r / min, the reaction temperature is 120 °C, and the reaction time is 180 min. The solid is filtered to obtain the alkaline leaching residue.

[0078] (3) Alkali leaching activation: The sodium hydroxide alkaline solution and the alkaline leaching residue obtained in step (2) are placed in a high-pressure reactor and reacted in a homogeneous reactor, wherein the sodium hydroxide concentration is 400 g / L, the liquid-solid ratio is 15:1, the speed of the homogeneous reactor is 100 r / min, the reaction temperature is 260 °C, and the reaction time is 180 min. The solid is filtered to obtain alkali-leached activated carbon.

[0079] (4) Centrifugal water washing: The alkali-leached activated carbon obtained in step (3) is placed in a centrifuge, hydrochloric acid is added to adjust the pH value to neutral, and then washed with water. The centrifuge speed is 15000 r / min, the washing time is 15 min, and the liquid-solid ratio is 50:1. After the first centrifugal water washing to adjust the pH to neutral, repeat the ultrapure water washing three times to obtain washed residue.

[0080] (5) Pickling: Place hydrochloric acid and the slag obtained in step (4) in a magnetic stirrer for reaction. The concentration of hydrochloric acid is 30%, the temperature is 85 °C, the liquid-solid ratio is 50:1, and the pickling time is 15 h. After pickling, repeat water washing until the pH of the washing solution is neutral. After adjusting the concentration of the pickling solution, it can be reused in the pickling process to finally obtain the raw material of the hard carbon negative electrode material.

[0081] (6) Silicon precipitation: The deashing liquid obtained in step (2) is subjected to a silicon precipitation process to obtain a crude silicon product, and the alkaline washing liquid can be reused in the alkaline leaching process.

[0082] (7) Aluminum precipitation: The secondary deashing liquid obtained in step (3) is subjected to an aluminum precipitation process to obtain a crude aluminum product. The secondary alkaline washing liquid can be reused in the alkaline leaching activation process.

[0083] The obtained hard carbon anode material raw material was prepared into a hard carbon anode material using the method described in Chinese invention patent CN118545697A, "Hard Carbon Anode Material, Preparation Method, and Application thereof," and then assembled to obtain a sodium ion battery, as described in Example 1. The resulting sodium ion battery had a charge capacity of 306.9 mAh / g, a discharge capacity of 333.2 mAh / g, and an initial efficiency of 92.11%.

[0084] Obviously, the above embodiments are merely example for clearly illustrating but not limitation to the embodiments. Based on the above description, other different forms of changes or variations can be made by those skilled in the art. Here, all the embodiments need not and can not be enumerated. The obvious changes or variations derived from the above description are still within the protection scope of the present application.

Claims

1. A method for preparing hard carbon negative electrode material raw material from bituminous coal, characterized by: Using bituminous coal as the main raw material, the ash in the bituminous coal is removed through the processes of crushing, alkali leaching, alkali leaching activation, centrifugal water washing, and acid leaching to prepare a hard carbon negative electrode material raw material. The resulting deashing liquid is subjected to silicon precipitation and aluminum precipitation processes to achieve silicon and aluminum separation and alkaline solution recycling. The specific method includes the following steps: Step (1), crushing: placing bituminous coal in a crusher to obtain bituminous coal powder; Step (2), alkali leaching: placing a sodium hydroxide solution and the bituminous coal powder obtained in step (1) in a high-pressure reactor and reacting them in a homogeneous reactor, filtering the solid to obtain an alkali leaching residue; Step (3), alkali leaching activation: placing a sodium hydroxide solution and the alkali leaching residue obtained in step (2) in a high-pressure reactor and reacting them in a homogeneous reactor, filtering the solid to obtain alkali-leached activated carbon; Step (4), centrifugal washing: placing the alkali-leached activated carbon obtained in step (3) in a centrifuge, adding sulfuric acid or hydrochloric acid solution to adjust the pH value to neutral, and then washing with water to obtain washed residue; Step (5), acid leaching: placing a sulfuric acid or hydrochloric acid solution and the washed residue obtained in step (4) in a magnetic stirrer to react to obtain a hard carbon negative electrode material raw material; Step (6), silicon precipitation: the deashing liquid obtained in step (2) is subjected to a silicon precipitation process to obtain a crude silicon product, and the alkaline washing liquid can be reused in the alkaline leaching process in step (2); Step (7), aluminum precipitation: the secondary deashing liquid obtained in step (3) is subjected to an aluminum precipitation process to obtain a crude aluminum product, and the secondary alkaline washing liquid can be reused in the alkaline leaching activation process in step (3); In step (3), the concentration of the sodium hydroxide solution is 240-400 g / L, the mass ratio of the sodium hydroxide solution to the alkali leaching residue is (8-15):1, the speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 200-280 °C, and the reaction time is 60-180 min.

2. The method according to claim 1, wherein: In step (1), dry grinding is adopted, and the particle size of the obtained bituminous coal powder is not less than 100 mesh.

3. The method according to claim 1, wherein: In step (2), the concentration of the sodium hydroxide solution is 160-320 g / L, the mass ratio of the sodium hydroxide solution to the bituminous coal powder is (8-15):1, the speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 85-120 ° C, and the reaction time is 60-180 min.

4. The method according to claim 1, wherein: In step (4), the centrifuge speed is 5000-15000 r / min, the water washing time is 5-15 min, the liquid-to-solid ratio of each water washing is (20-50):1, and the ultrapure water washing is repeated 3 times.

5. The method according to claim 1, wherein: In step (5), the concentration of the sulfuric acid or hydrochloric acid solution is 20-30%, the temperature in the magnetic stirrer is 45-85 ° C, the mass ratio of the sulfuric acid or hydrochloric acid solution to the washed slag is (20-50): 1, the reaction time is 8-15 h, and after the reaction is completed, the washing solution is washed with water until the pH value is neutral to obtain the hard carbon negative electrode material raw material.

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