Coal-based solid waste micro-electrolysis ball, preparation method thereof and dye wastewater treatment method

Abstract

The application relates to a coal-based solid waste micro-electrolysis ball and a preparation method and a dye wastewater treatment method, wherein the coal-based solid waste micro-electrolysis ball is prepared by uniformly mixing a solid mixture and a sodium silicoaluminate aqueous solution and then high-temperature calcining; the solid mixture comprises coal-based solid waste, steel slag and kaolin, the mass ratio of the coal-based solid waste to the steel slag is 0.5-2, and the content of the kaolin is 20% of the mass of the solid mixture; the mass fraction of the sodium silicoaluminate aqueous solution is 2-5%, and the solid-liquid ratio of the sodium silicoaluminate aqueous solution to the solid mixture is 1-5 g / ml. The dye wastewater treatment method adopts a three-stage micro-electrolysis tank, the adsorption-electrochemical-flocculation mechanism of the micro-electrolysis ball is strengthened by changing a micro-electrolysis environment, high-salt strong-acid dye wastewater is efficiently pretreated, the coupling of multiple mechanisms is realized, and the utilization rate of the micro-electrolysis ball is improved. The application realizes comprehensive utilization of the coal-based solid waste and the steel slag, treats waste with waste, and improves the sewage treatment effect through a three-stage wastewater treatment process.

Description

Technical Field

[0001] This application belongs to the field of comprehensive utilization technology of coal-based solid waste, specifically relating to a coal-based solid waste micro-electrolysis ball and its preparation method, and a dye wastewater treatment method. Background Technology

[0002] Dye wastewater is characterized by high color intensity, high organic matter concentration, complex composition, numerous recalcitrant substances, and large amounts of inorganic salts and sulfides, making it a difficult-to-treat industrial wastewater. Especially for strongly acidic azo dyes, dyeing requires acidic baths, and neutral salts are added during the dyeing process to slow down the dyeing process. The resulting highly acidic and saline wastewater has a sulfuric acid content of around 10%, making direct biological treatment impossible. The cost of conventional physicochemical treatment technologies is insufficient to meet practical pretreatment needs. In the wastewater treatment process, the pH of the wastewater plays a crucial role in the treatment effect of each stage. Directly adjusting the pH using chemical reagents is costly and increases the salinity load on subsequent treatment processes. Furthermore, the addition of limestone or lime slurry generates a large amount of solid waste.

[0003] The annual output of coal-based solid waste is approximately 1.5 billion tons. The current situation of large-scale temporary stockpiling not only causes serious environmental pollution problems, but also wastes the unique resources contained in coal-based solid waste. Coal-based solid waste mainly includes coal gangue, fly ash, and coal gasification slag, which are rich in silicon, aluminum, and carbon, have a relatively abundant porous structure and a large specific surface area, and have great application prospects in water treatment.

[0004] Currently, some technical solutions utilize iron-carbon packing material made from coal-based solid waste (gasification slag) to treat wastewater, achieving good results. However, in practical applications, it has been found that this iron-carbon packing / wastewater treatment method suffers from significant losses in strongly acidic wastewater, low electron utilization in the material, and fails to fully utilize the mechanism of action of micro-electrolysis balls at each pH value, resulting in poor wastewater treatment effects and low utilization of iron-carbon materials. Summary of the Invention

[0005] In view of the above analysis, the present invention aims to provide a coal-based solid waste micro-electrolysis ball and its preparation method, as well as a dye wastewater treatment method, to solve the above-mentioned problems existing in the prior art.

[0006] The objective of this invention is achieved as follows:

[0007] In a first aspect, a micro-electrolysis ball for coal-based solid waste is provided, which is made by mixing a solid mixture with an aqueous solution of sodium aluminosilicate and then calcining it at high temperature; the solid mixture includes coal-based solid waste, steel slag and kaolin, the mass ratio of coal-based solid waste to steel slag is 0.5-2, and the content of kaolin is 20% of the mass of the solid mixture; the mass fraction of the aqueous solution of sodium aluminosilicate is 2-5%, and the solid-liquid ratio of the aqueous solution of sodium aluminosilicate to the solid mixture is 1-5 g / ml.

[0008] Furthermore, coal-based solid waste can be one or more combinations of coal gangue, fly ash, and gasification slag.

[0009] Furthermore, the solid mixture also includes a carbon source, and the mass ratio of iron component to carbon component in the solid mixture is 1-5.

[0010] Furthermore, the solid mixture also includes an ash source, wherein the acid-soluble ash in the solid mixture accounts for 20-60% by mass.

[0011] Furthermore, the coal-based solid waste micro-electrolysis sphere includes a first micro-electrolysis sphere, a second micro-electrolysis sphere, and a third micro-electrolysis sphere;

[0012] When preparing the first micro-electrolysis sphere, the mass ratio of iron to carbon in the solid mixture is controlled to be 1:5, the content of acid-soluble ash accounts for 50-60% of the total mass, and the mass fraction of sodium aluminosilicate aqueous solution is 2%; the particle size of the first micro-electrolysis sphere is 1 cm; during calcination, it is calcined at a constant temperature of 700℃ for 1 h under a nitrogen atmosphere, and the heating rate is 20℃ / min.

[0013] In preparing the second micro-electrolysis sphere, the mass ratio of iron to carbon in the solid mixture was controlled to be 1:1, the acid-soluble ash content accounted for 30-40% of the total mass, and the mass fraction of sodium aluminosilicate aqueous solution was 5%; the particle size of the second micro-electrolysis sphere was 5 cm; during calcination, it was calcined at 800 °C for 1 h under a nitrogen atmosphere, with a heating rate of 10 °C / min.

[0014] When preparing the third micro-electrolysis sphere, the mass ratio of iron to carbon components in the solid mixture is controlled to be 1:2, the content of acid-soluble ash accounts for 10-20% of the total mass, and the mass fraction of sodium aluminosilicate aqueous solution is 3-4%; the particle size of the second micro-electrolysis sphere is 2-3 cm; during calcination, it is calcined at a constant temperature of 900℃ for 1 h under a nitrogen atmosphere, and the heating rate is 15℃ / min.

[0015] Secondly, a method for preparing coal-based solid waste micro-electrolysis spheres is provided, comprising the following steps:

[0016] Coal-based solid waste, steel slag, and kaolin are thoroughly mixed into a solid mixture. The mass ratio of coal-based solid waste to steel slag is 0.5-2, and the kaolin content is 20% of the mass of the solid mixture.

[0017] Prepare a sodium aluminosilicate aqueous solution with a mass fraction of 2-5%, and mix it with the solid mixture during the granulation process, with a solid-liquid ratio of 1-5 g / ml;

[0018] To manufacture spherical particles, the spherical particles are first dried, and then the dried spherical particles are roasted to obtain coal-based solid waste micro-electrolysis spheres.

[0019] Furthermore, when drying the spherical particles, the spherical particles are dried under vacuum at 70°C until the moisture content is below 5%.

[0020] Furthermore, the dried spherical particles are calcined in a tube furnace at a high temperature of 700-900℃ for 1 hour under a nitrogen atmosphere, with a heating rate of 10-20℃ / min.

[0021] Thirdly, a method for treating dye wastewater is provided, which uses the aforementioned coal-based solid waste micro-electrolysis balls to treat dye wastewater; the dye wastewater treatment method includes the following steps:

[0022] The first micro-electrolysis ball, the second micro-electrolysis ball, and the third micro-electrolysis ball are respectively loaded into the first electrolytic cell, the second electrolytic cell, and the third electrolytic cell; the dye wastewater to be treated is electrolyzed in the first electrolytic cell, the second electrolytic cell, and the third electrolytic cell in sequence.

[0023] Furthermore, since the original wastewater has a pH of less than 1, during the reaction process in the first electrolytic cell, a paddle impeller is used to stir the wastewater below the micro-electrolysis ball packing column at a stirring speed of 50-80 r / min, thus obtaining the wastewater after the first stage of treatment.

[0024] The wastewater treated in the first stage is fed into the second electrolytic cell. The pH of the wastewater in the second electrolytic cell is adjusted to be maintained at 2-4. Disodium oxalate tetraacetate (0.001-0.005 mol / L) is added to the second electrolytic cell. Aeration is carried out during the reaction. The micro-electrolysis reaction lasts for 60-120 minutes to obtain the wastewater treated in the second stage.

[0025] The wastewater treated in the second stage is fed into the third electrolytic cell. The pH of the wastewater in the third electrolytic cell is adjusted to be maintained at 4-6. 0.001-0.005 mol / L of tert-butanol is added to the second electrolytic cell as a foaming agent. Aeration is carried out during the reaction, and the micro-electrolysis reaction lasts for 40-60 minutes.

[0026] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0027] a) The coal-based solid waste micro-electrolysis spheres provided by this invention are iron-carbon micro-electrolysis spheres prepared from coal-based solid waste and steel slag. The steel slag and coal-based solid waste form a galvanic cell in the wastewater, and the treatment effect is enhanced through micro-electrolysis. The coal-based solid waste contains a certain proportion of residual carbon and has a high specific surface area, which can improve the electron utilization rate in the micro-electrolysis reaction. The acidity in the wastewater is controlled by the ash content in the coal-based solid waste, which is economical and cost-effective. The coal-based solid waste after acid leaching and deashing can be used for boiler co-firing or to prepare porous silicon-carbon materials, thereby increasing added value.

[0028] b) The preparation method of the coal-based solid waste micro-electrolysis ball provided by the present invention is simple and low in cost.

[0029] c) The dye wastewater treatment method provided by the present invention uses three micro-electrolysis cells connected in series, and adds three kinds of micro-electrolysis balls with different characteristics to the three micro-electrolysis cells respectively, so as to enhance the different action mechanisms of the micro-electrolysis balls at different pH levels, combining the characteristics of coal-based solid waste and acidic wastewater, treating waste with waste, which is in line with the concept of sustainable development. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this specification or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings.

[0031] Figure 1 This is a flowchart of the dye wastewater treatment method in Example 3. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. It should be noted that, unless otherwise specified, the implementation methods and features in the implementation methods in this disclosure can be combined, separated, interchanged, and / or rearranged. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] Example 1

[0034] A specific embodiment of the present invention discloses a coal-based solid waste micro-electrolysis ball, which is made by mixing a solid mixture with an aqueous solution of sodium aluminosilicate and then calcining it at high temperature. The iron-carbon filler is spherical particles with a particle size of 1-5 cm. The solid mixture includes coal-based solid waste, steel slag, and kaolin, with a mass ratio of coal-based solid waste to steel slag of 0.5-2 and a kaolin content of 20% of the mass of the solid mixture. The sodium aluminosilicate aqueous solution has a mass fraction of 2-5%, and the solid-liquid ratio of the sodium aluminosilicate aqueous solution to the solid mixture is 1-5 g / ml.

[0035] In this embodiment, the coal-based solid waste can be one or more combinations of coal gangue, fly ash, and gasification slag. If the coal-based solid waste only uses gasification slag, the solid mixture is composed of gasification slag, steel slag, and kaolin.

[0036] Because steel slag has a low specific surface area, it can be directly dissolved in acidic wastewater, resulting in a low number of reactive sites and low electron utilization. However, when steel slag is combined with gasified fine slag with a large specific surface area to form micro-electrolysis spheres, these spheres can form galvanic cells in the wastewater. Through the action of electric field, pollutants are gathered on the surface of the micro-electrolysis spheres, which can achieve better treatment results for wastewater.

[0037] When preparing the solid mixture, the mass ratio of iron to carbon is controlled to be 1-5. The solid mixture also includes a carbon source, preferably anthracite, which is added to control the mass ratio of iron to carbon at 1-5. For example, if the carbon content in the coal-based solid waste is less than 20% of the mass fraction of the coal-based solid waste or the zero-valent iron content in the steel slag is less than 60% of the mass fraction of the steel slag, anthracite is added for co-roasting. By adding anthracite as a component, the carbon content can be increased and iron oxide can be reduced, thereby improving the iron-carbon ratio in the micro-electrolysis pellets to achieve better treatment results.

[0038] When preparing the solid mixture, the acid-soluble ash content is controlled to be 20-60% of the total mass. The solid mixture also includes an ash source, preferably alkaline bauxite slag, and the acid-soluble ash content is controlled to be 20-60% by adding alkaline bauxite slag. For example, if the acid-soluble ash content in the coal-based solid waste is less than 40% of the coal-based solid waste, alkaline bauxite slag is added to the solid mixture to improve the acid consumption performance of the micro-electrolysis balls and to prevent the iron components from precipitating out in large quantities in the acidic wastewater, thus reducing the effectiveness.

[0039] For example, coal-based solid waste micro-electrolysis spheres are prepared using gasification slag, iron powder, and kaolin as raw materials via a thermosetting high-temperature roasting method. Preparation method: Gasification slag with a carbon content of 20% and an acid-soluble ash content of 45% is dried in an oven at 100°C and then passed through a 100-mesh sieve. It is mixed with steel slag ground to 100 mesh at a 1:1 mass ratio, and kaolin with a mass fraction of 20% is added as a binder. The three are thoroughly mixed, and deionized water containing 2% sodium aluminosilicate is added dropwise to granulate into spherical particles approximately 1 cm in size. The spherical particles are then dried in an oven under vacuum at 70-80°C. To prevent high-temperature oxidation, calcination is performed in a tube furnace at 800°C in a nitrogen atmosphere. The heating program is as follows: the temperature is increased from room temperature to 800°C at a rate of 15°C / min and held at that temperature for 60 minutes before heating is stopped. The spheres are then cooled to room temperature to obtain the coal-based solid waste micro-electrolysis spheres. The roasted coal-based solid waste micro-electrolysis spheres have a rich pore structure and a specific surface area as high as 178.7 m². 2The material has high mechanical strength and forms a large amount of ferrous silicate component, exhibiting good acid resistance. Under aeration conditions, it was used to treat Acid Red GR dye wastewater with an initial pH of 2. After 120 minutes of reaction, the decolorization rate reached 86.48%, COD decreased from 84.28 mg / L to 29.13 mg / L, and the B / C ratio increased from 0.249 to 1.373, significantly improving biodegradability. This demonstrates that the coal-based solid waste micro-electrolysis balls have a good treatment effect on acid dye wastewater, and that the gasified fine slag is feasible as a micro-electrolysis material. After the reaction, acid-dissolved iron, calcium, and aluminum ions were detected in the wastewater, with iron ion dissolution at 110 mg / L, a relatively small amount. The pH of the wastewater increased from 2 to 3.87, remaining within the optimal reaction pH range throughout the process. This indicates that the gasified fine slag does indeed alleviate the acidity of the wastewater, with an ideal effect.

[0040] When using coal-based solid waste micro-electrolysis spheres to treat dye wastewater, the acidity of the wastewater changes continuously during the treatment process, with the pH value gradually increasing. To address the differences in pH values ​​between the early, middle, and late stages of wastewater treatment, this embodiment also provides three types of coal-based solid waste micro-electrolysis spheres: the first micro-electrolysis sphere, the second micro-electrolysis sphere, and the third micro-electrolysis sphere, each capable of treating wastewater at different stages.

[0041] The first micro-electrolysis sphere is used for high-acid and high-salt wastewater in the early stage of wastewater treatment. The composition and preparation process of the first micro-electrolysis sphere are as follows: In the solid mixture, the mass ratio of iron component to carbon component is controlled at 1:5. Alkaline bauxite slag is added so that the acid-soluble ash content accounts for 50-60% of the total mass, and the kaolin content is 20%. A sodium aluminosilicate aqueous solution with a mass fraction of 2% is prepared and thoroughly mixed with the solid mixture during the granulation process. The mixture is then granulated into spherical particles of about 1 cm by a disc pelletizer. The spherical particles are vacuum dried at 70°C until the moisture content is below 5%, and then sent to a tube furnace for constant temperature calcination at 700°C for 1 hour under a nitrogen atmosphere with a heating rate of 20°C / min. After cooling, the first coal-based solid waste micro-electrolysis sphere is obtained. Rapid heating causes the moisture inside the micro-electrolysis spheres to evaporate quickly, achieving the purpose of pore formation. This also reduces the wear resistance of the micro-electrolysis spheres themselves, causing their surface layer to peel off layer by layer during the reaction. The first micro-electrolysis sphere, with high acid-soluble components, small particle size, high porosity, and low wear resistance, can fully contact acidic wastewater, ensuring thorough acid dissolution of its soluble ash. While reducing pollutants, it effectively regulates the acidic wastewater, showing significant advantages in the initial stage of treating highly acidic wastewater. The wear resistance of the micro-electrolysis spheres is one of the required parameters for packing material use. If the strength is too low, it is easily broken by the aeration airflow during use, failing to meet application requirements. The micro-electrolysis spheres prepared in this embodiment have slightly reduced wear resistance, allowing their surface layer to peel off layer by layer during use, increasing the reaction contact area.

[0042] The second micro-electrolysis sphere is used for treating intermediate-acid and intermediate-salt wastewater in the mid-stage of wastewater treatment. The composition and preparation process of the second micro-electrolysis sphere are as follows: In a solid mixture, the mass ratio of iron to carbon is controlled at 1:1. Fly ash is added to ensure that the acid-soluble ash content accounts for 30-40% of the total mass, and the kaolin content is 20%. A 5% sodium aluminosilicate aqueous solution is prepared and thoroughly mixed with the solid mixture during granulation. The mixture is then granulated into 5cm spherical particles using a disc pelletizer. The spherical particles are vacuum-dried at 70℃ until the moisture content is below 5%, then sent to a tube furnace and calcined at 800℃ for 1 hour under a nitrogen atmosphere at a heating rate of 10℃ / min. After cooling, the second micro-electrolysis sphere is obtained. At temperatures above 800℃, the formation of a large amount of ferrous silicate is promoted, enhancing the bonding strength of the entire iron-carbon matrix. Furthermore, ferrous silicate is not easily oxidized or dissolved, and its formation has a catalytic promoting effect on the micro-electrolysis reaction process, which is beneficial for the long-term use of the micro-electrolysis sphere. The second micro-electrolysis ball, which has high mechanical strength, is more resistant to acid during the micro-electrolysis process and can be reused. It fully utilizes the role of micro-electrolysis decolorization reaction and has obvious advantages in the mid-stage of wastewater treatment.

[0043] The third micro-electrolysis sphere is used for low-acid and low-salt wastewater in the later stage of wastewater treatment. The composition and preparation process of the third micro-electrolysis sphere are as follows: In the solid mixture, the mass ratio of iron component to carbon component is controlled at 1:2, and acid-soluble ash content is added to make it account for 10-20% of the total mass, and the kaolin content is 20%; a sodium aluminosilicate aqueous solution with a mass fraction of 3-4% is prepared and thoroughly mixed with the solid mixture during the granulation process, and granulated into spherical particles of 2-3 cm by a disc pelletizer; the spherical particles are vacuum dried at 70℃ until the moisture content is below 5%, and then sent to a tube furnace for constant temperature calcination at 900℃ for 1 hour under a nitrogen atmosphere, with a heating rate of 15℃ / min. After cooling, the third micro-electrolysis sphere is obtained. The third micro-electrolysis ball has a low acid-soluble component, which can prevent the rapid increase of pH in low-acid wastewater from causing severe caking and passivation on the surface of the micro-electrolysis ball, resulting in surface deactivation and termination of the reaction. The moderate mechanical strength helps to wash away the surface, allowing the caking and passivated components on the surface to fall off quickly, which has a significant advantage in the later stage of wastewater treatment.

[0044] Compared with the prior art, the coal-based solid waste micro-electrolysis pellets provided in this embodiment have at least one of the following beneficial effects:

[0045] 1. Applying coal-based solid waste to the decolorization treatment of high-salt, high-acid dye synthesis wastewater efficiently utilizes the multi-component and well-developed porous structure of coal-based solid waste to achieve the goal of "treating waste with waste". Acid leaching effectively removes ash from the coal-based solid waste, increasing its added value, which is in line with the concept of sustainable development and reduces economic costs.

[0046] 2. By preparing micro-electrolysis balls from coal-based solid waste and steel slag, compared with direct acid dissolution of steel slag, the electron utilization rate is greatly improved, and the problem of high cost of using chemical reagents to directly adjust the pH of wastewater is also solved.

[0047] 3. Based on the acidity of acidic wastewater, three types of micro-electrolysis balls with different characteristics are provided to enhance the working mechanism of micro-electrolysis balls under different treatment conditions and maximize the treatment effect of micro-electrolysis balls on wastewater.

[0048] Example 2

[0049] This embodiment also provides a method for preparing coal-based solid waste micro-electrolysis spheres, used to prepare the coal-based solid waste micro-electrolysis spheres in Example 1. Taking gasification fine slag as an example, the preparation method includes the following steps:

[0050] Gasification slag, steel slag, and kaolin are thoroughly mixed into a solid mixture with a mass ratio of 0.5-2 for the gasification slag and steel slag, and a mass fraction of 20% for the kaolin. A sodium aluminosilicate aqueous solution with a mass fraction of 2-5% is prepared and thoroughly mixed with the solid mixture during granulation, with a solid-liquid ratio of 1-5 g / ml. The mixture is then granulated into spherical particles of 1-5 cm using a disc pelletizer. The spherical particles are vacuum dried at 70°C until the moisture content is below 5%, and then sent to a tube furnace for high-temperature calcination at 700-900°C for 1 hour under a nitrogen atmosphere, with a heating rate of 10-20°C / min. After cooling, coal-based solid waste micro-electrolysis pellets are obtained.

[0051] Furthermore, the preparation of spherical iron-carbon materials involves a two-step process. First, a first volume of iron-carbon material spheres with an average particle size of 1-3 cm is prepared using a mixture of the above-mentioned components. Then, these first volume iron-carbon material spheres are coated with alkaline bauxite slag to a thickness of 0.5-1 cm. Finally, the prepared spherical particles are vacuum-dried and then calcined in a tube furnace. After cooling, coated coal-based solid waste micro-electrolysis spheres are obtained. These coated coal-based solid waste micro-electrolysis spheres can be used to treat highly acidic dye wastewater. The outer layer of alkaline bauxite slag neutralizes the acidity of the wastewater, raising the pH to the optimal pH for the micro-electrolysis reaction, reducing acid consumption of iron components, and increasing electron utilization.

[0052] Example 3

[0053] Another specific embodiment of the present invention discloses a method for treating dye wastewater. The method uses coal-based solid waste micro-electrolysis balls from Example 1 or coal-based solid waste micro-electrolysis balls prepared by the method in Example 2 to treat dye wastewater. This method employs a three-stage electrolysis system to treat the wastewater. The three-stage electrolysis system includes a first electrolytic cell, a second electrolytic cell, and a third electrolytic cell connected sequentially. The first, second, and third electrolytic cells are respectively equipped with first, second, and third micro-electrolysis balls. Wastewater pretreatment (first stage), intermediate treatment (second stage), and post-treatment (third stage) are carried out sequentially in the three micro-electrolysis cells. By employing a three-stage micro-electrolysis method to treat wastewater, different carbon-iron materials are selected based on factors such as the acidity and salt content of the wastewater in each electrolytic cell. This fully utilizes and enhances the multiple mechanisms of action of the micro-electrolysis balls under different acidic conditions, including adsorption, electrochemical reduction, free radical oxidation, and flocculation adsorption, resulting in better treatment effects. Furthermore, the carbon-iron materials are less prone to caking and passivation, which is beneficial for long-term use.

[0054] The dye wastewater treatment method in this embodiment has the following operation process flow: Figure 1 As shown, it includes the following steps:

[0055] The first micro-electrolysis ball, the second micro-electrolysis ball, and the third micro-electrolysis ball are respectively loaded into the first electrolytic cell, the second electrolytic cell, and the third electrolytic cell;

[0056] The dye wastewater to be treated is electrolyzed in the first electrolytic cell, the second electrolytic cell, and the third electrolytic cell in sequence.

[0057] Specifically, the raw wastewater is fed into the first electrolytic cell. During the reaction, a paddle impeller is used to continuously stir the mixture below the micro-electrolysis ball packing column at a speed of 50-80 r / min. This ensures thorough mixing of the liquid, avoids concentration polarization, and improves reaction efficiency. On the other hand, excessively high speed will affect the contact between the micro-electrolysis balls and the wastewater and may damage the micro-electrolysis balls. After reacting for 40-60 minutes, the wastewater after the first stage of treatment is obtained.

[0058] Subsequently, the wastewater treated in the first stage in the first electrolytic cell is fed into the second electrolytic cell. The pH of the wastewater in the second electrolytic cell is maintained at 2-4 by adjusting the raw water. Micron-sized aeration discs are placed under the micro-electrolysis ball packing column for aeration. 0.001-0.005 mol / L of disodium oxalate tetraacetate is added to the second electrolytic cell. The micro-electrolysis reaction is carried out for 60-120 minutes to obtain the wastewater treated in the second stage.

[0059] Subsequently, the wastewater treated in the second stage in the second electrolytic cell is fed into the third electrolytic cell. The pH of the wastewater in the third electrolytic cell is maintained at 4-6 by adjusting the raw water. Micron-sized aeration discs are placed below the micro-electrolysis ball packing column for aeration. 0.001-0.005 mol / L of tert-butanol is added to the second electrolytic cell as a foaming agent. The micro-electrolysis reaction is carried out for 40-60 minutes to obtain the wastewater treated in the third stage. At this point, the expected wastewater treatment standard has been met, and the color removal rate is over 90%.

[0060] After the high-salt, high-acid dye wastewater passes through three micro-electrolysis cells in sequence, the color is reduced and pollutants are removed. A large amount of sulfate is also reduced in content through electrostatic adsorption, calcium ion sedimentation, flocculation adsorption and electrochemical reduction during the three-stage micro-electrolysis treatment process, ultimately achieving the ideal treatment effect.

[0061] In one alternative embodiment, after the first batch of wastewater is treated, the remaining portion of the micro-electrolysis balls in the second and third electrolytic cells is screened out and added to the first electrolytic cell. This mixture is then combined with the pre-loaded third micro-electrolysis balls before the second batch of wastewater is fed into the cell. This not only meets the requirement for efficient wastewater treatment but also fully utilizes the iron-carbon materials in the latter two electrolytic cells, improving the utilization rate of these materials and reducing costs.

[0062] The treatment principle of the three-stage electrolysis of wastewater in this embodiment is as follows:

[0063] Based on the different mechanisms of action of the micro-electrolysis balls at different pH values, the treatment effects of the three micro-electrolysis cells were enhanced. The initial pH of the raw water was low, generally below 2. Therefore, in the first micro-electrolysis cell, the main function was to consume some of the hydrogen ions in the raw water, initially raising the pH of the wastewater. Simultaneously, the raw water was too acidic to generate free radicals and flocculants; at this point, the degradation of the wastewater mainly relied on the reduction effect of micro-electrolysis. Since the wastewater contained a large amount of ferrous iron, stirring was used instead of aeration in the first electrolysis cell to prevent aeration from reducing the reducing atmosphere in the wastewater. After the acid components were consumed in the first micro-electrolysis cell, the residence time was controlled to bring the pH of the wastewater to 2 before it entered the second micro-electrolysis cell. In the second micro-electrolysis cell, less ferrous iron dissolved, reducing the reduction effect. Therefore, aeration was used to increase the oxygen content in the wastewater, enhancing the oxidation of hydroxyl and oxygen free radicals, and promoting the synergistic process of micro-electrolysis and Fenton-like reactions. The optimal pH for micro-electrolysis is between 2 and 4. Due to the ash content of the gasified slag, the pH of the wastewater continuously increases. Therefore, the pH is controlled within this range by adjusting the acidity of the raw water. In the second micro-electrolysis tank, the rising pH causes the dissolved iron and aluminum ions to hydrolyze and form hydroxyl polymers, which inhibit Fenton-like reactions. A large number of complexes adhere to the surface of the micro-electrolysis spheres, reducing their reactivity. Therefore, disodium ethylenediaminetetraacetate is added as a metal ion flocculant masking agent to enhance the oxidation effect of free radicals. After the reaction in the second micro-electrolysis tank, the wastewater enters the third micro-electrolysis tank. The acidity of the raw water is used to maintain the wastewater in the third micro-electrolysis tank at a pH between 4 and 5. A foaming agent is added to increase the aeration rate. After the reaction in the first two micro-electrolysis cells, a large number of metal ions such as iron and aluminum gather in the third micro-electrolysis cell. Under the weakly acidic atmosphere of pH 4-5, a large number of macromolecular complexes and flocculants are formed. The pollutants in the wastewater also lose their hydrophilic groups under the action of the first two micro-electrolysis cells and are easily adsorbed and aggregated by flocculation and removed from the water. Under the action of the foaming agent, the pollutants are quickly separated from the wastewater through air flotation.

[0064] Furthermore, a pH monitoring device is installed in each micro-electrolysis cell to detect the pH changes of the wastewater in real time. Each section uses the acidity of the raw water and the acid-soluble components in the micro-electrolysis balls to regulate the pH, so that each micro-electrolysis cell is in the optimal reaction conditions, thus reducing the cost of acid-base regulation.

[0065] Furthermore, the three-stage electrolysis system also includes multiple solid-liquid separators. Specifically, a solid-liquid separator is installed after each of the three micro-electrolysis cells to collect the acid-insoluble silicon-carbon components that detach from the surface of the micro-electrolysis spheres during the micro-electrolysis reaction. These components are then gathered into a mixing and stirring unit, where they are thoroughly leached using the acidity of the raw water to recover the silicon-carbon components. After acid leaching and deashing, the recovered silicon-carbon components have an increased carbon content and can be used for boiler co-firing or to separate porous silicon. Alternatively, the silicon-carbon components can be separated by flotation for the preparation of higher value-added porous materials.

[0066] After passing through three micro-electrolysis cells, the acidity and color of the wastewater are significantly reduced, large molecular pollutants are broken down into smaller molecules, and the biodegradability is greatly increased.

[0067] Considering that micro-electrolysis spheres may become passivated and caked during long-term operation, and that a large amount of sulfate complexes may occupy the active sites on the surface of the micro-electrolysis spheres during the treatment of high-salt wastewater, leading to deactivation, this embodiment of the three-stage electrolysis system also includes a spray device. The spray device periodically rinses each reaction tank through pH-controlled pipelines to ensure long-term stable operation of the process. During rinsing, the spray device above the micro-electrolysis tank sprays acidic wastewater to rinse the packing material inside the micro-electrolysis tank, washing away the surface passivation layer. Immersion is not recommended, as it would cause corrosion of the packing material. Here, the acidic wastewater is used as the rinsing solution, which saves costs and also controls the pH of the strongly acidic wastewater.

[0068] Compared with the prior art, the dye wastewater treatment method provided in this embodiment is carried out in three micro-electrolysis cells. Each micro-electrolysis cell is filled with micro-electrolysis balls with different properties. By adjusting the macroscopic physical parameters, the treatment performance of micro-electrolysis is improved to serve different reaction conditions. The decolorization ability of the micro-electrolysis balls is maximized, and the treatment effect of wastewater is better under the same consumption.

[0069] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A coal-based solid waste micro-electrolysis sphere, characterized in that, It is prepared by mixing a solid mixture with an aqueous solution of sodium aluminosilicate and then calcining it at high temperature; the solid mixture includes coal-based solid waste, steel slag and kaolin, the mass ratio of coal-based solid waste and steel slag is 0.5-2, and the content of kaolin is 20% of the mass of the solid mixture; the mass fraction of the aqueous solution of sodium aluminosilicate is 2-5%, and the solid-liquid ratio of the aqueous solution of sodium aluminosilicate to the solid mixture is 1-5 g / ml; The coal-based solid waste micro-electrolysis sphere includes a first micro-electrolysis sphere, a second micro-electrolysis sphere, and a third micro-electrolysis sphere; When preparing the first micro-electrolysis sphere, the mass ratio of iron to carbon in the solid mixture is controlled to be 1:5, the content of acid-soluble ash accounts for 50-60% of the total mass, and the mass fraction of sodium aluminosilicate aqueous solution is 2%; the particle size of the first micro-electrolysis sphere is 1 cm; during calcination, it is calcined at a constant temperature of 700℃ for 1 h under a nitrogen atmosphere, and the heating rate is 20℃ / min. When preparing the second micro-electrolysis sphere, the mass ratio of iron to carbon in the solid mixture is controlled to be 1:1, the content of acid-soluble ash accounts for 30-40% of the total mass, and the mass fraction of sodium aluminosilicate aqueous solution is 5%; the particle size of the second micro-electrolysis sphere is 5 cm; during calcination, it is calcined at 800℃ for 1 h under a nitrogen atmosphere, and the heating rate is 10℃ / min. When preparing the third micro-electrolysis sphere, the mass ratio of iron to carbon components in the solid mixture is controlled to be 1:2, the content of acid-soluble ash accounts for 10-20% of the total mass, and the mass fraction of sodium aluminosilicate aqueous solution is 3-4%; the particle size of the second micro-electrolysis sphere is 2-3 cm; during calcination, it is calcined at a constant temperature of 900℃ for 1 h under a nitrogen atmosphere, and the heating rate is 15℃ / min.

2. The coal-based solid waste micro-electrolysis sphere according to claim 1, characterized in that, Coal-based solid waste comprises one or more of the following: coal gangue, fly ash, and gasification slag.

3. A method for treating dye wastewater, characterized in that, The method for treating dye wastewater using the coal-based solid waste micro-electrolysis balls described in claim 1 includes the following steps: The first micro-electrolysis ball, the second micro-electrolysis ball, and the third micro-electrolysis ball are respectively loaded into the first electrolytic cell, the second electrolytic cell, and the third electrolytic cell; the dye wastewater to be treated is electrolyzed in the first electrolytic cell, the second electrolytic cell, and the third electrolytic cell in sequence.

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