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

Abstract

The invention discloses a method for preparing a raw material of a hard carbon negative electrode material from bituminous coal, which comprises the following steps: by taking the bituminous coal as a main raw material, removing ash substances in the bituminous coal through the processes of crushing, alkaline leaching, alkaline leaching activation, centrifugal washing and acid leaching to prepare the raw material of the hard carbon negative electrode material. And the produced deashing liquid is subjected to silicon precipitation and aluminum precipitation processes to realize separation of silicon and aluminum and recycling of alkali liquor. According to the method, high-value utilization of the bituminous coal in the field of preparation of the sodium-ion battery hard carbon negative electrode material is realized, meanwhile, separation and extraction of valuable components such as silicon and aluminum are realized, a direction is found for high-value resource utilization of the bituminous coal, and meanwhile, conditions are created for low-cost preparation of the sodium-ion battery negative electrode material. The method has the characteristics of comprehensive utilization of valuable components, low cost and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and in particular to a method for preparing hard carbon negative electrode material raw material from bituminous coal. Background Art

[0002] As a form of coal, bituminous coal primarily reflects its energy properties. With the further implementation of policies, the amount of coal used and its applicable scenarios are shrinking, necessitating the urgent need to explore high-value material utilization scenarios for bituminous coal. Sodium-ion battery anode materials, primarily hard carbon materials, are key components of sodium-ion batteries and directly impact their performance. Using bituminous coal to prepare sodium-ion battery anode materials would not only achieve high-value utilization of bituminous coal, but also provide a new raw material solution for hard carbon anode materials in sodium-ion batteries.

[0003] Chinese patent CN119695152A discloses a “coal-based hard carbon negative electrode material and its preparation method”, which removes ash from coal and activates carbon materials through acid treatment, pre-carbonization, steam activation and other steps. The hard carbon negative electrode material obtained by this process can achieve an initial efficiency of 80% or more than 83%, but the excessively long process flow and relatively strict raw material requirements limit its subsequent development. Chinese invention patent CN119683603A discloses a “method for preparing coal-based hard carbon negative electrode materials using coal-based materials as raw materials”, which realizes the preparation of hard carbon negative electrode materials through processes such as crushing, acid washing and deashing, pre-carbonization, and steam activation. The acid washing process of this process uses a combination of two or more of hydrochloric acid, hydrofluoric acid, and nitric acid, which is dangerous and polluting, and large-scale production has certain challenges. Chinese invention patent CN118545697A discloses a “hard carbon negative electrode material and its preparation method and application”, which also removes ash by acid washing, and inevitably causes waste of valuable components in the ash. Therefore, if bituminous coal can be used to prepare hard carbon negative electrode materials for sodium ion batteries while simplifying the process flow and realizing the recycling of valuable components, it will further realize the high-value material utilization of bituminous coal, while reducing the preparation cost of hard carbon negative electrode materials, creating conditions for subsequent large-scale production. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for preparing hard carbon negative electrode material raw materials from bituminous coal. The method uses crushing, alkaline leaching, alkaline leaching activation, centrifugal water washing, and acid leaching to prepare hard carbon negative electrode material for sodium ion batteries. This method not only realizes the high-value material utilization of bituminous coal, but also can recover valuable components such as silicon and aluminum. It is a low-cost, environmentally friendly method for preparing hard carbon negative electrode material raw materials from bituminous coal.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions: The present invention provides a method for preparing hard carbon negative electrode material raw material from bituminous coal. The method uses bituminous coal as the main raw material, removes ash from the bituminous coal through the processes of crushing, alkali leaching, alkali leaching activation, centrifugal water washing, and acid leaching to prepare the hard carbon negative electrode material raw material. The generated deashing liquid is subjected to silicon precipitation and aluminum precipitation processes to achieve silicon and aluminum separation and the recycling of the alkali liquid.

[0006] In the above technical solution, 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).

[0007] In the above technical solution, step (1) adopts a dry grinding method, and the particle size of the obtained bituminous coal powder is not less than 100 mesh.

[0008] In the above technical solution, 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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

[0013] 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

[0014] 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.

[0015] 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.

[0016] 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: (1) Crushing: Place the bituminous coal in a crusher and use dry grinding to obtain bituminous coal powder with a particle size of not less than 100 mesh.

[0017] (2) Alkali leaching: placing sodium hydroxide alkaline solution and the bituminous coal powder obtained in step (1) in a high-pressure reactor and reacting them in a homogeneous reactor, wherein the sodium hydroxide concentration is 160-320 g / L, the liquid-solid ratio is (8-15):1, the speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 85-120 °C, the reaction time is 60-180 min, and the solid is filtered to obtain the alkaline leaching residue.

[0018] (3) Alkali leaching activation: placing the sodium hydroxide alkaline solution and the alkaline leaching residue obtained in step (2) in a high-pressure reactor and reacting them in a homogeneous reactor, wherein the sodium hydroxide concentration is 240-400 g / L, the liquid-solid ratio is (8-15):1, the speed of the homogeneous reactor is 20-100 r / min, the reaction temperature is 200-280 °C, the reaction time is 60-180 min, and the solid is filtered to obtain alkali-leached activated carbon.

[0019] (4) Centrifugal water washing: Place the alkali-leached activated carbon obtained in step (3) in a centrifuge, add sulfuric acid or hydrochloric acid to adjust the pH value to neutral, and then wash with water. The centrifuge speed is 5000-15000 r / min, the water washing time is 5-15 min each time, and the liquid-solid ratio is (20-50):1. After the first centrifugal water washing to adjust the pH to neutral, repeat the ultrapure water washing three times to obtain washed residue.

[0020] (5) Acid leaching: The acid solution and the washed residue obtained in step (4) are placed in a magnetic stirrer for reaction, wherein the acid solution is one of sulfuric acid or hydrochloric acid, the concentration is 20-30%, the temperature is 45-85 °C, the liquid-solid ratio is (20-50):1, the pickling time is 8-15 h, and after pickling, the washing is repeated with water 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.

[0021] (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.

[0022] The specific silicon precipitation process is as follows: carbon dioxide is introduced into the deashing liquid, and the carbon dioxide reacts with sodium silicate to produce silicic acid, thereby achieving silicon precipitation.

[0023] (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.

[0024] 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.

[0025] Example 1 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: (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.

[0026] (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.

[0027] (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.

[0028] (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.

[0029] (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.

[0030] (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.

[0031] (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.

[0032] The hard carbon negative electrode material raw material obtained in step (5) was prepared into a hard carbon negative electrode material by the method of "hard carbon negative electrode material and its preparation method and application" described in Chinese invention patent CN118545697A, and a sodium ion battery was obtained by assembling. The "hard carbon negative electrode material raw material" of the present invention is equivalent to the "deashing activated carbon" in patent CN118545697A. The hard carbon negative electrode material was prepared by the method of Example 1 in patent CN118545697A. Then, as described in paragraph

[0089] of patent CN118545697A, a slurry was prepared according to the mass ratio of hard carbon negative electrode material, small particle conductive carbon black (Super P), and sodium alginate in an 8:1:1 ratio, and evenly coated on copper foil. After it was dried, it was cut into pole pieces with a diameter of 14 mm, and metallic sodium was used as the counter electrode. After it was assembled into a button cell in a glove box, a constant current charge and discharge test was carried out, with a voltage range of 0 2.5 V and a current of 20 mAg -1 The test results show that the obtained sodium ion battery has a charge capacity of 294.0 mAh / g, a discharge capacity of 337.3 mAh / g, and an initial efficiency of 87.16%.

[0033] Example 2 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: (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.

[0034] (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 200 g / L, the liquid-solid ratio is 10:1, the speed of the homogeneous reactor is 100 r / min, the reaction temperature is 120 °C, and the reaction time is 90 min. The solid is filtered to obtain alkaline leaching residue.

[0035] (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.

[0036] (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 15,000 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.

[0037] (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 30%, the temperature is 85 °C, the liquid-solid ratio is 50:1, and the pickling time is 15 h. After pickling, the washing is repeated with water 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.

[0038] (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.

[0039] (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.

[0040] 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 302.7 mAh / g, a discharge capacity of 339.7 mAh / g, and an initial efficiency of 89.11%.

[0041] Example 3 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: (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.

[0042] (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 10:1, the speed of the homogeneous reactor is 20 r / min, the reaction temperature is 105 °C, and the reaction time is 90 min. The solid is filtered to obtain the alkaline leaching residue.

[0043] (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.

[0044] (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.

[0045] (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.

[0046] (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.

[0047] (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.

[0048] 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%.

[0049] Example 4 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: (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.

[0050] (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 8:1, the speed of the homogeneous reactor is 20 r / min, the reaction temperature is 85 °C, and the reaction time is 60 min. The solid is filtered to obtain the alkaline leaching residue.

[0051] (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 240 g / L, the liquid-solid ratio is 8:1, the speed of the homogeneous reactor is 20 r / min, the reaction temperature is 240 °C, and the reaction time is 60 min. The solid is filtered to obtain alkali-leached activated carbon.

[0052] (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 5 min, and the liquid-solid ratio is 20:1. After the first centrifugal water washing to adjust the pH to neutral, repeat the ultrapure water washing three times to obtain washed residue.

[0053] (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 45 °C, the liquid-solid ratio is 20:1, 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.

[0054] (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.

[0055] (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.

[0056] 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 289.6 mAh / g, a discharge capacity of 338.3 mAh / g, and an initial efficiency of 85.60%.

[0057] Example 5 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 acid and alkali are reused. The main technical solutions are as follows: (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.

[0058] (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.

[0059] (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.

[0060] (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.

[0061] (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.

[0062] (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.

[0063] (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.

[0064] 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%.

[0065] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing hard carbon negative electrode material raw material from bituminous coal, characterized by: Taking 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 the raw material of hard carbon negative electrode material. The generated deashing liquid is separated from silicon and aluminum through silicon precipitation and aluminum precipitation processes, and the alkali liquid is recycled.

2. The method according to claim 1, wherein: 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).

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

4. The method according to claim 2, 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.

5. The method according to claim 2, wherein: 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.

6. The method according to claim 2, 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.

7. The method according to claim 2, characterized in that: 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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