Composite coke powder cold press molding regenerant and preparation method thereof

Abstract

The invention discloses a composite coke powder cold press molding regenerant and a preparation method thereof. The core composition of the regenerant comprises core-shell structure biomass fibers prepared through multi-step modification, molasses residues, alkali-activated magnesium residues, a CMC water-retaining agent and water. The preparation method comprises the following steps: firstly, carrying out surface pretreatment, silane coupling agent functionalization, nano silicon dioxide loading and magnesium compound deposition coating on biomass fibers to construct reinforced fibers with a special core-shell structure; the magnesium slag is activated by alkali liquor so as to improve the reaction activity of the magnesium slag. Then all the components and coke powder are subjected to premixing, liquid phase feeding and high-speed shearing according to a specific proportion to form a uniform wet forming material; the material can be subjected to cold press molding at normal temperature, and a formed coke product is obtained through subsequent drying.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization and clean energy technology, specifically relating to a technology for preparing composite binders from industrial solid waste and using them for cold pressing of coke powder to produce high-performance coke. Background Technology

[0002] Coke powder is a grayish-black fine-particle byproduct with a particle size of less than 5 mm, formed during the coke preparation, crushing, and transfer processes.

[0003] With tightening resource supplies and increasingly stringent environmental policies, promoting the high-value resource utilization of coke powder has become a crucial issue facing the industry. Currently, the main methods for recycling coke powder both domestically and internationally include: using it as general industrial fuel, blending it into coking coal, producing activated carbon, and using it as raw material for shaped coke. While using it as fuel can consume coke powder to some extent, the ultrafine fraction remains difficult to utilize effectively; the technology for re-blending coke powder in coking is not yet mature, the addition ratio is limited, and the actual consumption is low; while the preparation of activated carbon from coke powder for wastewater treatment is still in the exploratory stage, with limited application scale. In contrast, preparing shaped coke from coke powder through a molding process to partially replace conventional coke is technically feasible. Coke powder generally has a fixed carbon content exceeding 70%, making it a high-value carbon material. After being processed into shaped coke products with certain dimensions and mechanical strength through appropriate molding processes, it can be widely used in metallurgy, domestic fuel, industrial heating, and gasification feedstock. Conducting research on coke powder molding technology and its applications not only helps save coal resources but also increases the added value of by-products and reduces overall enterprise costs, resulting in significant economic and environmental benefits.

[0004] Currently, coke production processes can be divided into two categories based on raw material characteristics: hot pressing and cold pressing. While hot pressing offers advantages such as no binder required, high fixed carbon content, and good mechanical strength, it is particularly unsuitable for low-binding materials like coke powder due to the need for high-temperature insulation, complex equipment, high energy consumption, and the potential release of harmful gases during production. This limits its industrial application. In contrast, cold pressing, with its simpler process, lower forming temperature, and lower pressure requirements, has become the main research direction for coke powder forming. Because coke powder has poor self-binding ability, regenerators are often needed to achieve particle bonding. Under mechanical force, the regenerator can embed into the surface and pores of coke powder particles, forming a cemented or crystalline structure that imparts good strength to the coke. Regenerators are one of the core materials for cold pressing. Commonly used organic regenerators include coal tar, pitch, phenolic resin, lignin, molasses waste liquor, pulp black liquor, and polyvinyl alcohol, but their cost is high, and regenerators such as coal tar and resins often require high-temperature carbonization treatment, increasing process complexity. Inorganic regenerators such as bentonite, water glass, cement, and lime, while widely available and inexpensive, generally suffer from insufficient cold strength, high ash content, and low calorific value, which are detrimental to the production of high-quality coke. Therefore, developing composite regenerators that are low-cost, have excellent strength, high calorific value, and low ash content has become an important research direction in current coke powder cold pressing technology.

[0005] Based on existing technical conditions, this invention focuses on using a novel regenerator system that is widely available, requires small amounts, and has a simple molding process. The composite regenerator formulation is optimized through orthogonal experimental methods, and the traditional pressurization process is improved. A low-temperature and low-pressure molding method is adopted to achieve a low-energy-consumption and environmentally friendly coke powder molding technology path. Summary of the Invention

[0006] The technical problem to be solved: A composite coke powder cold-pressing regenerator and its preparation method solve the problem of poor formability of coke powder itself and overcome the defects of single organic binders, thereby enhancing the mechanical strength and thermal stability of the coke.

[0007] Technical solution: A composite coke powder cold-pressing regenerator, comprising the following components by weight: Core-shell structured biomass fiber: 15-25 parts; Molasses residue: 5-15 portions; Alkali-activated magnesium slag: 3-5 parts; CMC water-retaining agent: 0.5~1.5 parts; Water: 30-40 parts; The core-shell structured biomass fiber is a modified biomass fiber with a nano-silica layer and a magnesium compound layer sequentially coated on its surface.

[0008] Preferably, the core-shell structured biomass fiber is prepared by a method comprising the following steps: S1. After the biomass fiber is crushed to less than 0.5 mm, it is put into a mixed modification solution composed of 1.0%~5.0% H2O2 solution and 0.5%~2.0% glacial acetic acid. The mixture is reacted at 60~80℃ for 1~3 h. After the reaction is completed, the mixture is filtered, washed until neutral, and dried to obtain modified biomass fiber. S2. The modified biomass fiber obtained in step S1 is placed in a 1.0%~3.0% vinyltriethoxysilane ethanol solution and ultrasonically treated at 40~60℃ for 30~60 min. After treatment, it is taken out, washed, and dried to obtain silane coupling agent functionalized fiber. S3. Disperse the functionalized fibers obtained in step S2 in water to prepare a 3%~7% suspension, add 3%~8% of nano silica powder equivalent to the fiber mass, and shear and disperse at a high speed of 8000~12000 r / min for 20~40 min to allow the nano silica particles to be fully adsorbed on the fiber surface. Then filter and dry to obtain biomass fibers with SiO2 loaded on the surface. S4. Disperse the fiber obtained in step S3 in water to prepare a 2%~5% suspension, add MgCl2·6H2O and stir to dissolve it completely, then add ammonia dropwise while stirring to adjust the pH of the system to 9.0~10.5, and react at 60~80℃ for 2~4h; after the reaction is completed, filter, wash and dry to obtain the core-shell structured biomass fiber.

[0009] Preferably, the activation method of the activated magnesium slag includes the following steps: a1. The raw magnesium slag is ball-milled and screened to a particle size of less than 0.5 mm, then added to a sodium hydroxide solution with a mass concentration of 1.0%~3.0%, and stirred at a constant temperature of 70~90℃ for 1~2 h; b1. After the reaction in step a1 is completed, the solid product is filtered and dried to obtain the activated magnesium slag.

[0010] The preparation method of the above-mentioned composite coke powder cold-pressing regenerator: S11. After stirring the molasses residue to prepare a uniform solution, add CMC water-retaining agent and stir at a constant temperature of 60~80℃ for 1~3 hours; S12. Core-shell structured biomass fiber, alkali-activated magnesium slag and coke powder dry base raw materials are premixed at a ratio of 20~30:5~10:60~75 to obtain a uniform dry mixture; S13. Add the solution prepared in step S11 to the dry mixture in step S12, and mix using a high-speed shearing device until a uniform wet molding material is formed. S14. The wet molding material from step S13 is mixed in proportion and cold-pressed under a pressure of 20~30 MPa, and then naturally air-dried or dried at low temperature to obtain the molded coke.

[0011] Preferably, sodium alginate is added in step S11, and the amount added is 1 to 5% of the weight of molasses residue.

[0012] Preferably, the total amount of water added in step S13 is such that the water content of the final wet-formed material accounts for 8% to 15% of the total mass of the material.

[0013] Preferably, in step S13, the rotational speed of the high-speed shearing is 10000~15000 r / min, and the high-speed shearing time is 15~30 min.

[0014] Preferably, the amount of magnesium chloride hexahydrate added is 1:3 to 1:5 based on the mass ratio of magnesium ions provided to fibers.

[0015] Preferably, the biomass fiber in the step is one or more of corn stalks, sugarcane bagasse, sawdust, and rapeseed stalks.

[0016] Preferably, the mixture is mixed in proportion, cold-pressed under a pressure of 20~30 MPa, and then naturally air-dried or dried at low temperature to obtain the coke.

[0017] Beneficial effects: The composite coke powder cold-pressed regenerator material of this invention has the following advantages: 1. The core-shell structured biomass fiber of the present invention significantly improves the specific surface area and surface roughness of the fiber through the surface coating of a nano-silica layer and a magnesium compound layer, thereby enhancing the mechanical interlocking effect between the fiber and coke powder particles. The nano-silica layer provides a large number of active silanol groups, which can form hydrogen bonds with oxygen-containing functional groups on the surface of coke powder; Mg(OH)2 is partially converted into a magnesium-based gel phase during the molding process, further strengthening the chemical bond between the fiber and the coke powder, thereby improving the compressive strength and abrasion resistance of the molded coke.

[0018] 2. Molasses residue contains abundant sugars, organic acids, and humic substances, which can form a viscous network structure during the molding process. This effectively coats coke powder particles and fills pores, improving the material's plastic deformation capacity. During the later drying or low-temperature carbonization process, it gradually cokes, forming a stable carbon skeleton structure, thereby enhancing the cold strength and thermal stability of the molded coke and preventing cracking or pulverization during molding.

[0019] 3. After alkali activation, the inert magnesium silicate phase of magnesium slag is partially converted into active MgO and Mg(OH)2. Upon mixing with water, a hydration reaction occurs to form magnesium gel. This gel phase can form a bridging structure between coke powder particles, enhancing the bonding strength. Simultaneously, the magnesium slag powder fills the gaps between particles, optimizing the porosity distribution of the coke and improving its density and mechanical properties.

[0020] 4. CMC water-retaining agent adsorbs and locks in moisture through the carboxymethyl groups in its molecular chain, delaying premature evaporation of moisture during molding and ensuring that the material has a sufficient plasticity time window. The addition of sodium alginate further forms an ionic cross-linked network structure, which works synergistically with CMC to enhance the viscosity and dispersion stability of wet materials, avoids localized cracking caused by moisture migration, and thus improves the uniformity and yield of coke molding.

[0021] 5. High-speed shearing at 10,000–15,000 r / min is used to fully disperse the core-shell fiber, activated magnesium slag, and other components in the liquid phase and uniformly coat the coke powder surface. This significantly increases the contact area and interfacial reaction efficiency between the components, effectively avoiding stress concentration caused by agglomeration. This ensures that the molded coke forms a dense and uniform microstructure during cold pressing, resulting in a final product with high strength and low breakage rate after molding under 20–30 MPa pressure. Detailed Implementation

[0022] The present invention will be further described below with reference to embodiments. These embodiments are illustrative of the present invention, but the present invention is not limited to these embodiments: A composite coke powder cold-pressing regenerator, by weight, comprises the following components: Core-shell structured biomass fiber: 15-25 parts; Molasses residue: 5-15 portions; Alkali-activated magnesium slag: 3-5 parts; CMC water-retaining agent: 0.5~1.5 parts; Water: 30-40 parts; The core-shell structured biomass fiber is a modified biomass fiber with a nano-silica layer and a magnesium compound layer sequentially coated on its surface.

[0023] The aforementioned biomass fibers possess excellent toughness and tensile strength. They interweave with the coke powder particles, forming a three-dimensional, flexible network skeleton structure. This skeleton, like the reinforcing bars in reinforced concrete, effectively disperses and withstands external pressure, preventing brittle fracture of the coke under pressure or drop, greatly improving the mechanical strength and drop strength of the coke. The nano-silica particles have extremely high specific surface area and reactivity. They coat the fiber surface, significantly increasing the fiber roughness. The coated magnesium compound chemical binder, after molding, especially during subsequent curing or use, reacts with water and CO2 that may be introduced from molasses residue or air. Molasses residue is a natural binder. Its numerous -OH groups can bind tightly to coke powder particles and biomass fibers through hydrogen bonds, providing initial binding force. This gives the mixture good agglomeration and plasticity before pressing. The viscosity of molasses also improves the material's flowability during pressing, making it easier to fill the mold, resulting in a more uniform coke density and a smoother surface. As an organic material, molasses is also combustible. Unlike inorganic binders, it doesn't increase ash content in the coke; instead, it slightly increases the calorific value of the coke. Activated magnesium slag releases OH⁻ ions upon contact with water, creating a strongly alkaline environment. This environment can stimulate the activity of other components. CMC can adsorb a large amount of water and form a gel, effectively preventing water from evaporating or being lost too quickly during mixing and pressing. This ensures sufficient water participates in the various hydration reactions mentioned above. The viscosity of the CMC solution increases the material's viscosity, improves plasticity, and also acts as a lubricant during pressing, reducing energy consumption.

[0024] Preferably, the core-shell structured biomass fiber is prepared by a method comprising the following steps: S1. One or more of the following materials are crushed to less than 0.5 mm and then added to a mixed modification solution consisting of 1.0%~5.0% H2O2 solution and 0.5%~2.0% glacial acetic acid. The mixture is reacted at 60~80℃ for 1~3 hours. After the reaction is completed, the mixture is filtered, washed until neutral, and dried to obtain modified biomass fiber. S2. The modified biomass fiber obtained in step S1 is placed in a 1.0%~3.0% vinyltriethoxysilane ethanol solution and ultrasonically treated at 40~60℃ for 30~60 min. After treatment, it is taken out, washed, and dried to obtain silane coupling agent functionalized fiber. S3. Disperse the functionalized fibers obtained in step S2 in water to prepare a 3%~7% suspension, add 3%~8% of nano silica powder equivalent to the fiber mass, and shear and disperse at a high speed of 8000~12000 r / min for 20~40 min to allow the nano silica particles to be fully adsorbed on the fiber surface. Then filter and dry to obtain biomass fibers with SiO2 loaded on the surface. S4. Disperse the fiber obtained in step S3 in water to prepare a 2%~5% suspension, add MgCl2·6H2O and stir to dissolve it completely. The amount of magnesium chloride hexahydrate added is 1:3~1:5 based on the mass ratio of magnesium ions provided to the fiber. Then, add ammonia water dropwise while stirring to adjust the pH of the system to 9.0~10.5, and react at 60~80℃ for 2~4 hours. After the reaction is completed, filter, wash and dry to obtain the core-shell structured biomass fiber.

[0025] In step S1 above, glacial acetic acid provides an acidic environment and participates in the weak acid hydrolysis of lignin and hemicellulose in the fiber, initially destroying the inert structure on the fiber surface; H2O2, under weak acid and heating conditions, is a mild oxidant. It can effectively oxidize the -OH on the fiber surface, generating more -CHO and -COOH oxygen-containing functional groups; Step S2 above acts as a bridge connecting the fiber and the inorganic nanolayer. The silanol groups generated by hydrolysis undergo a dehydration condensation reaction with the abundant hydroxyl groups on the fiber surface from step S1, forming strong CO-Si-covalent bonds. In this way, the vinyl groups of the silane coupling agent extend outward, changing the fiber surface from a hydrophilic surface to a vinyl-containing surface. Step S3 above firmly coats the fiber surface with a layer of high specific surface area and high surface energy nano-SiO2 particles. This greatly increases the roughness of the fiber, providing a huge adhesion area and nucleation sites for the subsequent deposition of magnesium compounds; In step S4 above, ammonia water provides OH- - Ions, with Mg 2+ The ionic reaction produces Mg(OH)2.

[0026] Preferably, the activation method of the activated magnesium slag includes the following steps: a1. The raw magnesium slag is ball-milled and screened to a particle size of less than 0.5 mm, then added to a sodium hydroxide solution with a mass concentration of 1.0%~3.0%, and stirred at a constant temperature of 70~90℃ for 1~2 h; b1. After the reaction in step a1 is completed, the solid product is filtered and dried to obtain the activated magnesium slag.

[0027] The above-mentioned a1 ball milling process, which increases the specific surface area, followed by the addition of NaOH solution, disrupts the dense structure on the surface of the magnesium slag particles, exposing more of the internal CaO and MgO. This opens up the reaction pathways. The above-mentioned b1 terminates the alkali activation reaction and removes excess alkali solution and a small amount of soluble salts generated in the reaction, preventing these soluble substances from precipitating in subsequent coke, affecting product strength or causing moisture absorption.

[0028] The preparation method of the above-mentioned composite coke powder cold-pressing regenerator: S11. After stirring the molasses residue to prepare a uniform solution, add CMC water-retaining agent and stir at a constant temperature of 60~80℃ for 1~3 hours; S12. Core-shell structured biomass fiber, alkali-activated magnesium slag and coke powder dry base raw materials are premixed at a ratio of 20~30:5~10:60~75 to obtain a uniform dry mixture; S13. Add the solution prepared in step S11 to the dry mixture in step S12, and mix using a high-speed shearing device. The high-speed shearing speed is 10000~15000 r / min, and the high-speed shearing time is 15~30 min, until a uniform wet molding material is formed. S14. The wet molding material from step S13 is mixed in proportion and cold-pressed under a pressure of 20~30 MPa, and then naturally air-dried or dried at low temperature to obtain the molded coke.

[0029] The molasses residue in step S11 is viscous, so it is first prepared into a solution to facilitate the addition of CMC. CMC itself is a high molecular polymer, and the molecular chains need time and temperature to fully extend and hydrate.

[0030] The core-shell fibers in step S12 are lightweight and easily agglomerate; the activated magnesium slag is used in small quantities but plays a crucial role; coke powder is the main matrix. If they are directly mixed with liquid, the lightweight fibers will first be encapsulated by the liquid and form clumps, while the heavy particles will sink to the bottom, resulting in extremely uneven distribution. Therefore, liquid-solid composite mixing is performed.

[0031] The above step S13 uses high-speed shearing to stretch the viscous liquid into a thin film, which strongly and evenly coats the surface of each coke powder, magnesium slag and fiber, achieving maximum area contact.

[0032] Preferably, sodium alginate is added in step S11, with the amount added being 1-5% of the weight of the molasses residue. When sodium alginate containing Ca is added... 2+ or Mg 2+ In the system, the carboxyl groups of sodium alginate react instantaneously with these cations to form a preliminary, weak three-dimensional network structure in the material.

[0033] Preferably, the total amount of water added in step S13 is such that the water content of the final wet-formed material accounts for 8% to 15% of the total mass of the material, providing optimal plasticity and lubricity, which is beneficial for compaction under pressure to obtain high density.

[0034] Example 1

[0035] A composite coke powder cold-pressing regenerator, by weight, comprises the following components: Core-shell structured wheat fiber: 15 parts; Molasses residue: 5 portions; Alkali-activated magnesium slag: 3 parts; CMC water-retaining agent: 0.5 parts; Water: 30 parts; The core-shell structured wheat fiber is a modified wheat fiber with a nano-silica layer and a magnesium compound layer sequentially coated on its surface.

[0036] Preferably, the core-shell structured wheat fiber is prepared by a method comprising the following steps: S1. Wheat is crushed to less than 0.5 mm and then put into a mixed modification solution consisting of 3.0% H2O2 solution and 1.0% glacial acetic acid. The mixture is reacted at 60°C for 1 hour. After the reaction is completed, the mixture is filtered, washed until neutral, and dried to obtain modified biomass fiber. S2. The modified wheat straw fiber obtained in step S1 is placed in a 1.0% vinyltriethoxysilane ethanol solution and ultrasonically treated at 40°C for 30 min. After treatment, it is taken out, washed, and dried to obtain silane coupling agent functionalized fiber. S3. Disperse the functionalized fibers obtained in step S2 in water to prepare a 5% suspension, add nano-SiO2 powder equivalent to 5% of the fiber mass, and disperse at high speed of 8000 r / min for 20 min to allow the nano-SiO2 particles to be fully adsorbed on the fiber surface. Then filter and dry to obtain wheat straw fiber with SiO2 loaded on the surface. S4. Disperse the fiber obtained in step S3 in water to prepare a 3% suspension, add MgCl2·6H2O and stir to dissolve it completely. The amount of magnesium chloride hexahydrate added is 1:3 based on the mass ratio of magnesium ions provided to the fiber. Then, ammonia water is added dropwise under stirring to adjust the pH of the system to 9.0, and the reaction is carried out at 60°C for 2 hours. After the reaction is completed, the mixture is filtered, washed and dried to obtain the core-shell structured wheat fiber.

[0037] Preferably, the activation method of the activated magnesium slag includes the following steps: a1. The raw magnesium slag was ball-milled and screened to a particle size of less than 0.5 mm and then added to a 2% sodium hydroxide solution. The mixture was stirred at a constant temperature of 70°C for 1 hour. b1. After the reaction in step a1 is completed, the solid product is filtered and dried to obtain the activated magnesium slag.

[0038] The preparation method of the above-mentioned composite coke powder cold-pressing regenerator: S11. After mixing the molasses residue to prepare a uniform solution, add CMC water-retaining agent and stir at a constant temperature of 60~80℃ for 1~3 hours; add sodium alginate, the amount of which is 3% of the weight of the molasses residue.

[0039] S12. Core-shell structured wheat fiber, alkali-activated magnesium slag, and coke powder dry base raw materials are premixed at a ratio of 20:5:75 to obtain a uniform dry mixture; S13. Add the solution prepared in step S11 to the dry mixture in step S12, and mix using a high-speed shearing device. The high-speed shearing speed is 10000 r / min, and the high-speed shearing time is 15 min. The total amount of water added is such that the water content of the final wet molding material accounts for 10% of the total mass of the material. Continue until a uniform wet molding material is formed. S14. The wet molding material from step S13 is mixed in proportion and cold-pressed under a pressure of 25 MPa, and then naturally air-dried or dried at low temperature to obtain the molded coke.

[0040] Example 2

[0041] The difference between Example 2 and Example 1 is that the main components of the composite coke powder cold-pressing regenerator are: 20 parts of core-shell structured wheat fiber, 10 parts of molasses residue, 5 parts of alkali-activated magnesium slag, 1 part of CMC water-retaining agent, and 35 parts of water.

[0042] Example 3

[0043] The difference between Example 3 and Example 1 is that the main components of the composite coke powder cold-pressing regenerator are: 25 parts of core-shell structured wheat fiber, 15 parts of molasses residue, 4 parts of alkali-activated magnesium slag, 1.5 parts of CMC water-retaining agent, and 40 parts of water.

[0044] Example 4

[0045] The difference between Example 4 and Example 1 is that the core-shell structured biomass fiber is sugarcane bagasse.

[0046] Example 5

[0047] The difference between Example 5 and Example 1 is that the core-shell structured biomass fiber is rapeseed stalk.

[0048] Example 6

[0049] The difference between Example 6 and Example 1 is that the core-shell structured biomass fiber is wood chips.

[0050] Example 7

[0051] The difference between Example 7 and Example 1 is that the amount of magnesium chloride hexahydrate added in step S4 is 1:4 based on the mass ratio of magnesium ions provided to fiber.

[0052] Example 8

[0053] The difference between Example 8 and Example 1 is that the amount of magnesium chloride hexahydrate added in step S4 is 1:5 based on the mass ratio of magnesium ions provided to fiber.

[0054] Example 9

[0055] The difference between Example 9 and Example 1 is that in step S12, core-shell structured wheat fiber, alkali-activated magnesium slag and coke powder dry base raw materials are premixed at a ratio of 30:10:30 to obtain a uniform dry mixture.

[0056] Example 10

[0057] The difference between Example 10 and Example 1 is that in step S12, core-shell structured wheat fiber, alkali-activated magnesium slag and coke powder dry base raw materials are premixed at a ratio of 25:10:65 to obtain a uniform dry mixture.

[0058] Example 11

[0059] The difference between Example 11 and Example 1 is that the concentration of NaOH in step a1 is 3%.

[0060] Example 12

[0061] The difference between Example 12 and Example 1 is that the amount of sodium alginate added is 5% of the weight of molasses residue.

[0062] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the main components of the composite coke powder cold-pressing regenerator are: 30 parts of core-shell structured wheat fiber, 1 part of molasses residue, 10 parts of alkali-activated magnesium slag, 1 part of CMC water-retaining agent, and 40 parts of water.

[0063] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the main components of the composite coke powder cold-pressing regenerator are: 30 parts of core-shell structured wheat fiber, 1 part of molasses residue, 10 parts of alkali-activated magnesium slag, 1 part of CMC water-retaining agent, and 40 parts of water.

[0064] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the S2 silanization treatment is removed from the core-shell structure biomass preparation process.

[0065] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that the nano-SiO2 layer coated in step S3 is removed in the preparation process of core-shell structured biomass.

[0066] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is that the amount of magnesium chloride hexahydrate added in step S4 is 1:1 based on the mass ratio of magnesium ions provided to fibers.

[0067] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is that in step S12, core-shell structured wheat fiber, alkali-activated magnesium slag and coke powder dry base raw materials are premixed at a ratio of 40:10:50 to obtain a uniform dry mixture.

[0068] Comparative Example 7 The difference between Comparative Example 7 and Example 1 is that sodium alginate is not added in step S11.

[0069] Comparative Example 8 The difference between Comparative Example 8 and Example 1 is that step S1 does not involve glacial acetic acid modification.

[0070] Comparative Example 9 The difference between Comparative Example 9 and Example 1 is that heating and stirring are not performed in step S4.

[0071] Performance testing: Test Example 1 Compressive strength test: Three parallel samples were taken from each of the prepared coke products. After drying to constant weight at 105℃ and cooling to room temperature, the cylindrical coke samples (Ø50 mm * H50 mm) were subjected to axial compression testing using a universal testing machine at a constant loading rate of 10 mm / min. The maximum pressure value F that the sample withstood upon fracture was recorded. Compressive strength σ; The calculation formula is: σ = F / S, Where S is the cross-sectional area of ​​the sample (unit: mm) 2 The final result is the average of the three parallel sample test values.

[0072] Test Example 2 Drop strength test: For each of the prepared coke samples, take three parallel samples and weigh them first, M1. Then, drop each coke sample freely from a height of 2.0 m onto a steel plate with a thickness of not less than 15 mm, repeating this drop three times. Collect the fragments after the fall using a sieve with a mesh size of 5.0 mm, and weigh the mass of the material remaining on the sieve, M2. The drop strength DS is calculated using the formula: DS = (M2 / M1) × 100%. The final result is the average of the test values ​​of three parallel samples.

[0073] Test Example 3 Water absorption rate test: For each sample of the prepared coke product, take three parallel samples, dry them in an oven at 105℃ until constant weight, and weigh them as m1. Then, completely immerse the samples in distilled water at (25±5)℃ for 24 h, remove them, gently wipe off the free water on the surface with a damp gauze, and immediately weigh them as m2. Water absorption rate W A The calculation formula is: W A =[(m2–m1) / m1]×100%. The final result is the average of the three parallel sample test values.

[0074] To investigate the optimal cold-pressing parameters, a 6-factor, 3-level orthogonal experiment was designed. The orthogonal experimental table and experimental results are shown in Table 1.

[0075] Table 1. Six-factor, three-level orthogonal experimental table and experimental results.

[0076] Table 1 shows that the compressive strength is affected by several factors. Increased amounts of core-shell biomass fiber, molasses residue, and magnesium slag lead to an increase in strength. Increased shearing speed and time aid dispersion and improve strength. Excessive CMC may introduce too much ash or hinder molding, potentially causing a slight decrease in strength. Drop strength reflects the impact and abrasion resistance of the coke; the toughening and bonding effects of core-shell fiber and molasses residue significantly influence drop strength. Water absorption ranges from 6.2% to 8.5%. Lower water absorption indicates a dense coke structure and good hydrophobicity, which is beneficial for storage and transportation. Increased amounts of CMC and molasses residue usually improve water retention, potentially leading to a slight increase in water absorption. More thorough shearing results in more uniform material mixing, reduced porosity, and lower water absorption. The filling effect of magnesium slag also helps reduce water absorption.

[0077] Test Example 4 Viscosity: The apparent viscosity of the regenerant slurry was measured using a rotational viscometer at 25°C with a suitable rotor and rotation speed. Each sample was measured three times and the average value was taken.

[0078] Test Example 5 Electrical conductivity: The conductivity of the regenerator slurry was measured directly at 25°C using a laboratory conductivity meter. Each sample was measured three times and the average value was taken.

[0079] Test Example 6 Corrosiveness: The hanging plate method was adopted. A standard carbon steel test piece was partially immersed in the regenerating agent slurry and subjected to accelerated corrosion at 40°C for 7 days. After being removed, cleaned, dried, and weighed, the corrosion rate was calculated (unit: mm / a).

[0080] Test Example 7 Toxicological effects: Heavy metal leaching toxicity: Toxicity leaching tests were conducted on the cured coke products to detect the concentrations of heavy metals such as As, Ba, Cd, Cr, Pb, Hg, and Se.

[0081] Acute oral toxicity: Refer to the Material Safety Data Sheets (MSDS) of each component of the regenerant (molasses residue, CMC, sodium alginate, magnesium slag) for assessment.

[0082] Table 2 shows the performance tests for each embodiment and comparative example.

[0083] As shown in Table 2, Example 9 is typically characterized by high viscosity and high corrosivity, resulting in poor processability, demanding equipment requirements, and high overall costs. While Example 12 has the lowest water absorption rate, its extremely high viscosity severely limits flowability and production efficiency, making it difficult to meet the needs of continuous industrial production. Comparative Examples 1, 3, 5, and 7 have significant shortcomings in one or more aspects of performance or safety, rendering them unfeasible. The optimal formulation in Example 2 is 20 parts core-shell fiber, 10 parts molasses residue, 5 parts alkali-activated magnesium slag, 1 part CMC, and 35 parts water.

[0084] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite coke powder cold-pressing regenerator, characterized in that: By weight, it comprises the following components: Core-shell structured biomass fiber: 15-25 parts; Molasses residue: 5-15 portions; Alkali-activated magnesium slag: 3-5 parts; CMC water-retaining agent: 0.5~1.5 parts; Water: 30-40 parts; The core-shell structured biomass fiber is a modified biomass fiber with a nano-silica layer and a magnesium compound layer sequentially coated on its surface.

2. The composite coke powder cold-pressing regenerator according to claim 1, characterized in that: The core-shell structured biomass fiber is prepared by the following steps: S1. After the biomass fiber is crushed to less than 0.5 mm, it is put into a mixed modification solution composed of 1.0%~5.0% H2O2 solution and 0.5%~2.0% glacial acetic acid. The mixture is reacted at 60~80℃ for 1~3 h. After the reaction is completed, the mixture is filtered, washed until neutral, and dried to obtain modified biomass fiber. S2. The modified biomass fiber obtained in step S1 is placed in a 1.0%~3.0% vinyltriethoxysilane ethanol solution and ultrasonically treated at 40~60℃ for 30~60 min. After treatment, it is taken out, washed, and dried to obtain silane coupling agent functionalized fiber. S3. Disperse the functionalized fibers obtained in step S2 in water to prepare a suspension of 3% to 7%, add nano-silica powder equivalent to 3% to 8% of the fiber mass, and shear and disperse at high speed at 8000 to 12000 r / min for 20 to 40 min to allow the nano-silica particles to be fully adsorbed on the fiber surface. Then filter and dry to obtain biomass fibers with SiO2 loaded on the surface. S4. Disperse the fiber obtained in step S3 in water to prepare a 2%~5% suspension, add MgCl2·6H2O and stir to dissolve it completely, then add ammonia dropwise while stirring to adjust the pH of the system to 9.0~10.5, and react at 60~80℃ for 2~4h; after the reaction is completed, filter, wash and dry to obtain the core-shell structured biomass fiber.

3. The composite coke powder cold-pressing regenerator according to claim 1, characterized in that: The activation method for the activated magnesium slag includes the following steps: a1. The raw magnesium slag is ball-milled and screened to a particle size of less than 0.5 mm, then added to a sodium hydroxide solution with a mass concentration of 1.0%~3.0%, and stirred at a constant temperature of 70~90℃ for 1~2 h; b1. After the reaction in step a1 is completed, the solid product is filtered and dried to obtain the activated magnesium slag.

4. The preparation method of the composite coke powder cold-pressing regenerator according to claim 1, characterized in that: S11. After stirring the molasses residue to prepare a uniform solution, add CMC water-retaining agent and stir at a constant temperature of 60~80℃ for 1~3 hours; S12. Core-shell structured biomass fiber, alkali-activated magnesium slag and coke powder dry base raw materials are premixed at a ratio of 20~30:5~10:60~75 to obtain a uniform dry mixture; S13. Add the solution prepared in step S11 to the dry mixture in step S12, and mix using a high-speed shearing device until a uniform wet molding material is formed; S14. The wet molding material from step S13 is mixed in proportion and cold-pressed under a pressure of 20~30 MPa, and then naturally air-dried or dried at low temperature to obtain the molded coke.

5. The preparation method of the composite coke powder cold-pressing regenerator according to claim 4, characterized in that: In step S11, sodium alginate is added, and the amount added is 1-5% of the weight of molasses residue.

6. The preparation method of the composite coke powder cold-pressing regenerator according to claim 4, characterized in that: The total amount of water added in step S13 is such that the moisture content of the final wet-formed material accounts for 8% to 15% of the total mass of the material.

7. The preparation method of the composite coke powder cold-pressing regenerator according to claim 4, characterized in that: In step S13, the high-speed shearing speed is 10000~15000 r / min, and the high-speed shearing time is 15~30 min.

8. The composite coke powder cold-pressing regenerator according to claim 2, characterized in that: The amount of magnesium chloride hexahydrate added is 1:3 to 1:5 based on the mass ratio of magnesium ions provided to fibers.

9. The composite coke powder cold-pressing regenerator according to claim 4, characterized in that: The biomass fiber is one or more of the following: corn stalks, sugarcane bagasse, sawdust, and rapeseed stalks.

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