Preparation method of calcium carbide furnace front dust ball

Abstract

The application discloses a preparation method of calcium carbide furnace front dust ball, relates to the technical field of metal material recycling, and belongs to the patent classification C22B1 / 248. The method comprises the following steps: mixing calcium carbide furnace front dust with a composite binder, stirring and rolling to obtain mixed materials; pressure forming the mixed materials to obtain green ball embryos; vacuum impregnating the green ball embryos with a composite liquid containing nanometer silicon dioxide, ammonium bicarbonate and microcrystalline cellulose, then aging and curing to obtain primary ecological pressure balls; and then impregnating the primary ecological pressure balls with a silicon sol solution and drying, and then spraying a nanometer alumina suspension on the surface to obtain the dust ball. The dust ball prepared by the method has good mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of metal material recycling technology, belonging to patent classification number C22B1 / 248, specifically a method for preparing dust ash briquettes for pre-furnace dust removal in calcium carbide furnaces. Background Technology

[0002] During the calcium carbide production process, a large amount of furnace dust is generated in front of the furnace. This solid waste is collected by the dust removal system from the high-temperature flue gas during calcium carbide smelting. Its main components include unreacted calcium oxide, magnesium oxide, carbon powder, and calcium carbide dust, as well as small amounts of impurities such as silicon and iron. This type of dust is produced in large quantities. If directly piled up or landfilled, it will not only occupy a large amount of land resources, but the dust it contains will also spread under wind, causing air pollution. Some alkaline substances may also seep into the soil and groundwater, harming the ecological environment. At the same time, the usable components such as carbon powder contained in the dust will be wasted, which does not meet the industrial development needs of resource recycling.

[0003] To achieve the resource recovery of dust collected from the front of calcium carbide furnaces, dust ash briquetting technology has become one of the mainstream treatment methods. This technology involves mixing dust with an appropriate amount of binder, and then pressing it into briquettes of a certain shape and size using a briquetting device. These briquettes can be reused in calcium carbide smelting or used as raw materials in other industrial production. This reduces waste emissions, enables the secondary utilization of resources, lowers production costs for enterprises, and has significant economic and environmental benefits.

[0004] However, current calcium carbide furnace dust collection briquettes generally suffer from insufficient mechanical strength. On the one hand, the dust particles themselves are fine and highly fluid, making it difficult to control the uniformity of mixing with the binder, resulting in defects in the internal structure of the briquettes. On the other hand, the selection or proportion of existing binders is unreasonable, making it difficult to form a stable bond between the dust particles, and the briquette pressing process parameters (such as pressure and molding time) are not optimized enough, further affecting the strength of the briquettes. This strength deficiency will lead to a series of consequences: during the storage of the briquettes, they are prone to breakage due to their own weight or slight collisions, generating new dust and causing secondary pollution; during transportation, bumps and vibrations will cause a large number of briquettes to break, increasing transportation losses and costs; most importantly, when briquettes with insufficient strength enter the calcium carbide furnace for smelting, they will quickly break into fine powder, which not only makes it difficult to participate in the normal smelting reaction, but may also block the airflow channels in the furnace, affecting the stability of the furnace temperature and pressure, reducing calcium carbide production efficiency and product quality, and even causing abnormal furnace conditions and other production safety hazards. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing dust ash briquettes for calcium carbide furnace front-end dust collection, so as to solve the technical problem of insufficient mechanical strength of dust ash briquettes mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace includes the following steps:

[0008] S1. The dust collected in front of the calcium carbide furnace is mixed with the composite binder, and then stirred and compacted to obtain a mixture.

[0009] S2. Press the mixture into shape to obtain a green pellet;

[0010] S3. Vacuum impregnation of the green pellets with a composite liquid containing nano-silica, ammonium bicarbonate and microcrystalline cellulose, followed by curing and solidification to obtain the initial ecological pressed pellets;

[0011] S4. After impregnating the nascent briquette with a silica sol solution and drying it, the surface is sprayed with a nano-alumina suspension to obtain the dust removal briquette.

[0012] In this invention, the plant fibers in the composite binder interweave within the mixture to form a three-dimensional network skeleton structure, effectively bearing and dispersing external stress and preventing cracks during pressing. The dried plant stem powder fills the pores between the dust particles, significantly improving the bulk density and overall compactness of the briquettes. Simultaneously, inorganic binders such as sodium silicate and bentonite form strong bridges between particles through gelation, while polyacrylamide improves the overall wettability and uniformity of the material, ensuring the binder fully coats the particle surface. These processes give the mixture excellent initial plasticity and molding stability, facilitating subsequent molding.

[0013] Then, a microstructure enhancement effect is achieved by vacuum impregnation with a nanocomposite liquid combined with curing and solidification treatment. Nano-silica, as a reinforcing phase, is distributed in the interparticle gaps and pore walls, exerting a "pinning effect" to effectively hinder microcrack propagation and strengthen the matrix. On the other hand, when the briquettes are returned to the calcium carbide furnace in a high-temperature environment, a chemical reaction occurs inside (CaO + 3C → CaC2 + CO↑), generating a large amount of CO gas. Without pre-constructed pore channels, the gas accumulation leads to a sudden increase in internal pressure, causing the briquettes to burst and pulverize. To solve this problem, this invention uses ammonium bicarbonate and microcrystalline cellulose as pore-forming agents. During the solidification process, these decompose to generate gas, forming a controllable pore structure. This provides a pre-set escape channel for the gas generated by the chemical reaction, releasing internal pressure and avoiding structural damage caused by internal pressure accumulation, thereby ensuring the structural integrity and reaction stability of the briquettes under extreme high temperatures.

[0014] Finally, the surface properties of the briquette are enhanced by impregnating it with silica sol and spraying it with nano-alumina to form a high-strength protective layer. The silica sol penetrates the surface pores and gels after drying, forming a continuous and dense silicon-based protective film that effectively seals surface micro-cracks and significantly improves surface hardness and wear resistance. The sprayed nano-alumina suspension further forms a high-melting-point, high-hardness ceramic coating on the briquette's surface, acting like a "surface armor" and greatly enhancing the briquette's resistance to mechanical impact and high-temperature corrosion. Figure 1 This is a SEM image of the surface of the dust collector briquettes prepared in this invention. The combination of these two components enhances the overall strength and durability of the briquettes from the inside out, ultimately resulting in dust collector briquettes with excellent mechanical properties in both cold and hot states.

[0015] Preferably, in step S1, the amount of composite binder added is 5 to 10 wt% of the mass of the dust collected before the calcium carbide furnace.

[0016] Preferably, in step S1, the composite binder includes the following components: plant fiber, dried plant stem powder, polyacrylamide, sodium silicate, and bentonite.

[0017] Preferably, the composite adhesive comprises the following components in parts by weight:

[0018] 3-6 parts plant fiber, 8-10 parts dried plant stem powder, 0.1-0.3 parts polyacrylamide, 0.5-1.0 parts sodium silicate, and 0.4-0.8 parts bentonite.

[0019] Preferably, in step S2, the pressure molding includes pre-pressing, heat preservation treatment, and final pressing.

[0020] Preferably, in step S3, the mass ratio of green bulb embryo, nano-silica, ammonium bicarbonate and microcrystalline cellulose is 100:2~4:3~6:1~3.

[0021] Preferably, in step S3, γ-aminopropyltriethoxysilane is also added to the composite solution.

[0022] In the technical solution of this invention, as described above, ammonium bicarbonate and microcrystalline cellulose are used as pore-forming agents. During the curing process, they decompose to generate gas, forming a controllable porous structure. This provides a pre-set escape channel for the gas generated by the chemical reaction, releasing internal pressure and avoiding structural damage caused by internal pressure accumulation. This ensures the structural integrity and reaction stability of the briquette under extreme high temperatures. However, the research team found during experiments that the gas and pores generated by the decomposition of ammonium bicarbonate and microcrystalline cellulose impact and weaken the already formed solid skeleton, leading to an uncontrollable decrease in the overall mechanical properties of the briquette (especially compressive strength and drop strength). At the same time, the nano-silica particles are mainly physically filled with the matrix, resulting in weak bonding. Under stress, they are prone to interfacial peeling, failing to fully exert their reinforcing effect. To further address this technical problem, the present invention adds γ-aminopropyltriethoxysilane to the composite liquid. One end of the γ-aminopropyltriethoxysilane molecule has a functional group that can react with inorganic substances (such as nano-SiO2 and CaO in dust collector ash), and the other end has a functional group that can bind with organic substances through hydrogen bonding, thereby improving the overall bonding strength and avoiding the decrease in the mechanical strength of the sphere caused by the pore-forming agent.

[0023] Preferably, the amount of γ-aminopropyltriethoxysilane added is 0.5 to 1.5 wt% of the weight of the green embryo.

[0024] Preferably, in step S4, the mass concentration of the silica sol solution is 4-8 wt%.

[0025] Preferably, in step S4, the solid content of the nano-alumina suspension is 7-10 wt%.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] 1. By forming a three-dimensional network skeleton with plant fibers in the composite binder and filling the pores with plant stem powder, combined with the gelling effect of inorganic binder and the improvement of wettability with polyacrylamide, the plasticity, molding stability and bulk density of the mixture are effectively improved, and cracks are prevented during pressing.

[0028] 2. The composite liquid containing nano-silica, pore-forming agent and γ-aminopropyltriethoxysilane is vacuum impregnated. The nano-silica "pins" the cracks, the pore-forming agent creates gas escape channels to avoid high-temperature explosion, and the γ-aminopropyltriethoxysilane enhances the bonding force between the nanoparticles and the matrix, solving the problem of strength reduction caused by pore formation and strengthening the microstructure of the sphere.

[0029] 3. A dense silicon-based protective film is formed by impregnation with silica sol to seal micro-cracks on the surface, and then nano-alumina is sprayed to form a "surface armor", which significantly improves the surface hardness, wear resistance and resistance to mechanical impact and high temperature corrosion of the briquette, achieving excellent cold and hot mechanical properties of the briquette both inside and out. Attached Figure Description

[0030] Figure 1 This is a SEM image of the surface of the dust collection ash briquettes prepared in the pre-furnace area of ​​the calcium carbide furnace according to the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Example 1

[0033] A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace includes the following steps:

[0034] Step 1: Weigh 100 kg of dust collected from the calcium carbide furnace as the main raw material, and weigh 8 kg of composite binder, whose composition by weight is: 5 parts plant fiber (flax fiber), 9.5 parts dried plant stem powder (corn stalk powder), 0.2 parts polyacrylamide, 0.9 parts sodium silicate, and 0.7 parts calcium-based bentonite. Add the dust and composite binder together to a twin-shaft mixer and dry mix at 200 rpm for 5 minutes. Then, slowly spray deionized water to adjust the moisture content of the mixture to 12 wt%. Transfer the mixture to a roller mill mixer and compact it at 15 rpm for 8 minutes to obtain the final mixture.

[0035] Step 2: The mixture is fed into a hydraulic double-roller briquetting machine for pressure molding. First, pre-pressing is performed at 12MPa pressure and 75℃ roller temperature, with the roller gap width set at 6mm and the roller speed controlled at 13rpm to obtain a strip-shaped blank with uniform thickness. Then, the blank is conveyed to a 110℃ heat preservation box for static heat preservation for 4min. Finally, final pressing is performed at 20MPa pressure under normal temperature conditions, with the roller gap adjusted to 4mm, to obtain green pellets with a particle size of 30±2mm and a dense appearance.

[0036] Step 3: Weigh 3.5 kg of nano-silica (30 nm particle size), 5 kg of ammonium bicarbonate, 2.5 kg of microcrystalline cellulose, and 1.2 kg of γ-aminopropyltriethoxysilane, and disperse them together in 20 L of ethanol solution. Sonicate at 800 W for 30 min to form a uniform suspension, obtaining a composite solution. Place 100 kg of green pellet preforms in a vacuum impregnation tank, evacuate to -0.09 MPa, and spray the composite solution evenly onto the surface of the preforms through an atomizing nozzle. Impregnate under pressure for 15 min. After impregnation, transfer the preforms to a constant temperature and humidity curing chamber and cure at 60℃ and 85% humidity for 50 min. Then place them in a programmable temperature-controlled curing oven, increase the temperature to 180℃ at 3℃ / min, and hold for 40 min to complete segmented curing, obtaining nascent compressed pellets with an internal nano-reinforced porous structure.

[0037] Step 4: Immerse the nascent dust collection briquettes in a 7% (w / w) silica sol solution for 45 seconds, remove and drain until no more droplets drip from the surface. Then, place them in a 165℃ hot air circulating oven to dry for 25 minutes, forming a dense silica gel film on the surface. Finally, use an airless spraying device to uniformly spray a 9% (w / w) nano-alumina suspension (50nm particle size) onto the surface of the briquettes. The spraying amount is 5L of suspension per ton of briquettes. Flash dry at 80℃ for 10 minutes to form a high-hardness surface protective layer, obtaining the final dust collection briquettes.

[0038] Example 2

[0039] A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace includes the following steps:

[0040] Step 1: Weigh 100 kg of dust collected from the calcium carbide furnace as the main raw material, and weigh 6 kg of composite binder, whose composition by weight is: 4 parts plant fiber (flax fiber), 8.5 parts dried plant stem powder (corn stalk powder), 0.15 parts polyacrylamide, 0.6 parts sodium silicate, and 0.5 parts calcium-based bentonite. Add the dust and composite binder together to a twin-shaft mixer and dry mix at 200 rpm for 5 minutes. Then, slowly spray deionized water to adjust the moisture content of the mixture to 12 wt%. Transfer the mixture to a roller mill mixer and compact it at 15 rpm for 8 minutes to obtain the final mixture.

[0041] Step 2: The mixture is fed into a hydraulic double-roller briquetting machine for pressure molding. First, pre-pressing is performed at 12MPa pressure and 75℃ roller temperature, with the roller gap width set at 6mm and the roller speed controlled at 13rpm to obtain a strip-shaped blank with uniform thickness. Then, the blank is conveyed to a 110℃ heat preservation box for static heat preservation for 4min. Finally, final pressing is performed at 20MPa pressure under normal temperature conditions, with the roller gap adjusted to 4mm, to obtain green pellets with a particle size of 30±2mm and a dense appearance.

[0042] Step 3: Weigh 2.5 kg of nano-silica (30 nm particle size), 4 kg of ammonium bicarbonate, 1.5 kg of microcrystalline cellulose, and 0.8 kg of γ-aminopropyltriethoxysilane, and disperse them together in 20 L of ethanol solution. Sonicate at 800 W for 30 min to form a uniform suspension, obtaining a composite solution. Place 100 kg of green pellet preforms in a vacuum impregnation tank, evacuate to -0.09 MPa, and spray the composite solution evenly onto the surface of the preforms through an atomizing nozzle. Impregnate under pressure for 15 min. After impregnation, transfer the preforms to a constant temperature and humidity curing chamber and cure at 60℃ and 85% humidity for 50 min. Then place them in a programmable temperature-controlled curing oven, raise the temperature to 180℃ at 3℃ / min, and hold for 40 min to complete segmented curing, obtaining nascent compressed pellets with an internal nano-reinforced porous structure.

[0043] Step 4: Immerse the nascent dust collection briquettes in a 5% (w / w) silica sol solution for 45 seconds, remove and drain until no more droplets drip from the surface. Then, place them in a 165℃ hot air circulating oven to dry for 25 minutes, forming a dense silica gel film on the surface. Finally, use an airless spraying device to uniformly spray an 8% (w / w) nano-alumina suspension (50nm particle size) onto the surface of the briquettes. The spraying amount is 5L of suspension per ton of briquettes. Flash dry at 80℃ for 10 minutes to form a high-hardness surface protective layer, obtaining the final dust collection briquettes.

[0044] Example 3

[0045] A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace includes the following steps:

[0046] Step 1: Weigh 100 kg of dust collected from the calcium carbide furnace as the main raw material, and weigh 7 kg of composite binder, whose composition by weight is: 4.5 parts plant fiber (flax fiber), 9 parts dried plant stem powder (corn stalk powder), 0.2 parts polyacrylamide, 0.7 parts sodium silicate, and 0.6 parts calcium-based bentonite. Add the dust and composite binder together to a twin-shaft mixer and dry mix at 200 rpm for 5 minutes. Then, slowly spray deionized water to adjust the moisture content of the mixture to 12 wt%. Transfer the mixture to a roller mill mixer and compact it at 15 rpm for 8 minutes to obtain the final mixture.

[0047] Step 2: The mixture is fed into a hydraulic double-roller briquetting machine for pressure molding. First, pre-pressing is performed at 12MPa pressure and 75℃ roller temperature, with the roller gap width set at 6mm and the roller speed controlled at 13rpm to obtain a strip-shaped blank with uniform thickness. Then, the blank is conveyed to a 110℃ heat preservation box for static heat preservation for 4min. Finally, final pressing is performed at 20MPa pressure under normal temperature conditions, with the roller gap adjusted to 4mm, to obtain green pellets with a particle size of 30±2mm and a dense appearance.

[0048] Step 3: Weigh 3 kg of nano-silica (30 nm particle size), 4.5 kg of ammonium bicarbonate, 2 kg of microcrystalline cellulose, and 1.0 kg of γ-aminopropyltriethoxysilane, and disperse them together in 20 L of ethanol solution. Sonicate at 800 W for 30 min to form a uniform suspension, obtaining a composite solution. Place 100 kg of green pellet preforms in a vacuum impregnation tank, evacuate to -0.09 MPa, and spray the composite solution evenly onto the surface of the preforms through an atomizing nozzle. Impregnate under pressure for 15 min. After impregnation, transfer the preforms to a constant temperature and humidity curing chamber and cure at 60℃ and 85% humidity for 50 min. Then place them in a programmable temperature curing oven, increase the temperature to 180℃ at 3℃ / min, and hold for 40 min to complete segmented curing, obtaining nascent compressed pellets with an internal nano-reinforced porous structure.

[0049] Step 4: Immerse the nascent dust collection briquettes in a 6% (w / w) silica sol solution for 45 seconds, remove and drain until no more droplets drip from the surface. Then, place them in a 165℃ hot air circulating oven to dry for 25 minutes, forming a dense silica gel film on the surface. Finally, use an airless spraying device to uniformly spray an 8.5% solid content nano-alumina suspension (50nm particle size) onto the surface of the briquettes. The spraying amount is 5L of suspension per ton of briquettes. Flash dry at 80℃ for 10 minutes to form a high-hardness surface protective layer, obtaining the final dust collection briquettes.

[0050] Example 4

[0051] A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace includes the following steps:

[0052] Step 1: Weigh 100 kg of dust collected from the calcium carbide furnace as the main raw material, and weigh 10 kg of composite binder. The composition of this binder, by weight, is: 6 parts plant fiber (flax fiber), 10 parts dried plant stem powder (corn stalk powder), 0.3 parts polyacrylamide, 1.0 part sodium silicate, and 0.8 parts calcium-based bentonite. Add the dust and composite binder to a twin-shaft mixer and dry mix at 200 rpm for 5 minutes. Then, slowly spray deionized water to adjust the moisture content of the mixture to 12 wt%. Finally, transfer the mixture to a roller mill mixer and compact it at 15 rpm for 8 minutes to obtain the final mixture.

[0053] Step 2: The mixture is fed into a hydraulic double-roller briquetting machine for pressure molding. First, pre-pressing is performed at 12MPa pressure and 75℃ roller temperature, with the roller gap width set at 6mm and the roller speed controlled at 13rpm to obtain a strip-shaped blank with uniform thickness. Then, the blank is conveyed to a 110℃ heat preservation box for static heat preservation for 4min. Finally, final pressing is performed at 20MPa pressure under normal temperature conditions, with the roller gap adjusted to 4mm, to obtain green pellets with a particle size of 30±2mm and a dense appearance.

[0054] Step 3: Weigh 4 kg of nano-silica (30 nm particle size), 6 kg of ammonium bicarbonate, 3 kg of microcrystalline cellulose, and 1.5 kg of γ-aminopropyltriethoxysilane, and disperse them together in 20 L of ethanol solution. Sonicate at 800 W for 30 min to form a uniform suspension, obtaining a composite solution. Place 100 kg of green pellet preforms in a vacuum impregnation tank, evacuate to -0.09 MPa, and spray the composite solution evenly onto the surface of the preforms through an atomizing nozzle. Impregnate under pressure for 15 min. After impregnation, transfer the preforms to a constant temperature and humidity curing chamber and cure at 60℃ and 85% humidity for 50 min. Then place them in a programmable temperature curing oven, increase the temperature by 3℃ / min to 180℃, and hold for 40 min to complete segmented curing, obtaining nascent compressed pellets with an internal nano-reinforced porous structure.

[0055] Step 4: Immerse the nascent dust briquettes in an 8% (w / w) silica sol solution for 45 seconds, remove and drain until no more droplets drip from the surface. Then, place them in a 165℃ hot air circulating oven to dry for 25 minutes, forming a dense silica gel film on the surface. Finally, use an airless spraying device to uniformly spray a 10% (w / w) nano-alumina suspension (50nm particle size) onto the surface of the dust briquettes. The spraying amount is 5L of suspension per ton of dust briquettes. Flash dry at 80℃ for 10 minutes to form a high-hardness surface protective layer, obtaining the final dust removal dust briquettes.

[0056] Example 5

[0057] A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace includes the following steps:

[0058] Step 1: Weigh 100 kg of dust collected from the calcium carbide furnace as the main raw material, and weigh 5 kg of composite binder, whose composition by weight is: 3 parts plant fiber (flax fiber), 8 parts dried plant stem powder (corn stalk powder), 0.1 parts polyacrylamide, 0.5 parts sodium silicate, and 0.4 parts calcium-based bentonite. Add the dust and composite binder together to a twin-shaft mixer and dry mix at 200 rpm for 5 minutes. Then, slowly spray deionized water to adjust the moisture content of the mixture to 12 wt%. Transfer the mixture to a roller mill mixer and compact it at 15 rpm for 8 minutes to obtain the final mixture.

[0059] Step 2: The mixture is fed into a hydraulic double-roller briquetting machine for pressure molding. First, pre-pressing is performed at 12MPa pressure and 75℃ roller temperature, with the roller gap width set at 6mm and the roller speed controlled at 13rpm to obtain a strip-shaped blank with uniform thickness. Then, the blank is conveyed to a 110℃ heat preservation box for static heat preservation for 4min. Finally, final pressing is performed at 20MPa pressure under normal temperature conditions, with the roller gap adjusted to 4mm, to obtain green pellets with a particle size of 30±2mm and a dense appearance.

[0060] Step 3: Weigh 2 kg of nano-silica (30 nm particle size), 3 kg of ammonium bicarbonate, 1 kg of microcrystalline cellulose, and 0.5 kg of γ-aminopropyltriethoxysilane, and disperse them together in 20 L of ethanol solution. Sonicate at 800 W for 30 min to form a uniform suspension, obtaining a composite solution. Place 100 kg of green pellet preforms in a vacuum impregnation tank, evacuate to -0.09 MPa, and spray the composite solution evenly onto the surface of the preforms through an atomizing nozzle. Impregnate under pressure for 15 min. After impregnation, transfer the preforms to a constant temperature and humidity curing chamber and cure at 60℃ and 85% humidity for 50 min. Then place them in a programmable temperature-controlled curing oven, increase the temperature to 180℃ at 3℃ / min, and hold for 40 min to complete segmented curing, obtaining nascent compressed pellets with an internal nano-reinforced porous structure.

[0061] Step 4: Immerse the nascent dust collection briquettes in a 4% (w / w) silica sol solution for 45 seconds, remove and drain until no more droplets drip from the surface, then place them in a 165℃ hot air circulating oven to dry for 25 minutes, forming a dense silica gel film on the surface. Finally, use an airless spraying device to uniformly spray a 7% (50nm) nano-alumina suspension onto the surface of the briquettes, using 5L of suspension per ton of briquettes, and flash dry at 80℃ for 10 minutes to form a high-hardness surface protective layer, obtaining the final dust collection briquettes.

[0062] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the composite adhesive in step 1 lacks plant fiber and plant stem powder.

[0063] Comparative Example 2: The difference between Comparative Example 2 and Example 1 is that the composite liquid in step 3 lacks nano-silica.

[0064] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that the composite liquid in step 3 lacks the pore-forming agents ammonium bicarbonate and microcrystalline cellulose.

[0065] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the composite solution in step 3 lacks nano-γ-aminopropyltriethoxysilane.

[0066] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the initial ecological spheres in step 4 are not soaked in silica sol solution.

[0067] Comparative Example 6: The difference between Comparative Example 6 and Example 1 is that the initial ecological spheres in step 4 are not treated with nano-alumina suspension spraying.

[0068] Performance testing:

[0069] 1. Cold compressive strength test: Referring to the "Method for Determining the Cold Compressive Strength of Iron-Bearing Charge Briquettes for Blast Furnaces" (YB / T4203-2009), briquettes with a particle size of 30±2mm were selected from each sample, and 10 briquettes were randomly selected from each group as parallel samples. An electronic universal pressure testing machine (range 0-50kN, accuracy 0.01kN) was used to apply pressure axially to the briquettes at a uniform speed of 2mm / min. The maximum pressure value at the moment of briquette rupture was recorded, and the arithmetic mean of the 10 parallel samples was calculated, which is the cold compressive strength of the sample (unit: MPa). The test results are shown in Table 1.

[0070] 2. Drop Strength Test: Simulating impact damage during briquette transportation, 10 intact briquettes with a diameter of 30±2mm were selected for each group. The briquettes were dropped freely from a height of 2.0m, vertically impacting a horizontally placed Q235 steel plate (10mm thick, flatness ≤0.1mm / m). Each drop constituted one cycle. The briquettes were observed for cracks or breakage (crack length >3mm was considered damage). The number of cycles from the first drop to the appearance of damage for each briquette was recorded. The arithmetic mean of the 10 briquettes was taken as the drop strength (unit: cycles). The test results are shown in Table 1.

[0071] 3. Hot compressive strength test: Simulating the high-temperature working environment of a calcium carbide furnace (temperature 800℃, close to the preheating zone temperature of the furnace charge), 10 briquettes with a particle size of 30±2mm were selected from each group and placed in a programmed temperature-increasing muffle furnace. The temperature was increased to 800℃ at a rate of 5℃ / min and held for 30 minutes to ensure uniform temperature inside and outside the briquettes. The briquettes were then quickly removed and immediately placed on an electronic universal pressure testing machine. Using the same test parameters as the cold compressive strength test (loading rate 2mm / min), the maximum pressure at which the briquettes ruptured was measured. The arithmetic mean of the 10 parallel samples was calculated as the hot compressive strength (unit: MPa). The test results are shown in Table 1.

[0072] 4. High-Temperature Bursting Rate Test: To verify the anti-bursting effect of the pore-forming agents (ammonium bicarbonate, microcrystalline cellulose), 50 intact briquettes with a particle size of 30±2mm were selected from each group and placed in a muffle furnace. The temperature was increased to 1000℃ (simulating the extreme temperature of the high-temperature reaction zone of a calcium carbide furnace) at a rate of 10℃ / min. After holding at this temperature for 60min, heating was stopped, and the briquettes were allowed to cool naturally to room temperature. The number of briquettes that showed obvious bursting after cooling (cracks penetrating the briquettes or breaking into two or more pieces) was counted, and the bursting rate was calculated (bursting rate = number of bursting briquettes / total number of briquettes × 100%). The test results are shown in Table 1.

[0073] Table 1:

[0074] sample Cold compressive strength (MPa) Drop intensity (times) Hot compressive strength (800℃, MPa) High-temperature bursting rate (1000℃, %) Example 1 25.1 5.0 17.3 1.2 Example 2 24.2 4.5 16.4 1.6 Example 3 24.7 4.8 16.8 1.5 Example 4 25.6 5.3 17.5 1.0 Example 5 23.6 4.3 16.0 1.8 Comparative Example 1 10.3 2.1 6.5 15.3 Comparative Example 2 16.8 3.2 9.9 7.5 Comparative Example 3 25.6 5.7 17.8 45.6 Comparative Example 4 15.6 3.0 9.5 9.0 Comparative Example 5 20.4 3.6 14.1 2.8 Comparative Example 6 19.5 3.4 12.5 2.4

[0075] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace, characterized in that, Includes the following steps: S1. The dust collected in front of the calcium carbide furnace is mixed with the composite binder, and then stirred and compacted to obtain a mixture. The composite binder includes the following components: plant fiber, dried plant stem powder, polyacrylamide, sodium silicate, and bentonite; S2. Press the mixture into shape to obtain a green pellet; S3. Vacuum impregnation of the green pellets with a composite liquid containing nano-silica, ammonium bicarbonate and microcrystalline cellulose, followed by curing and solidification to obtain the initial ecological pressed pellets; S4. After impregnating the nascent briquette with a silica sol solution and drying it, the surface is sprayed with a nano-alumina suspension to obtain the dust removal briquette.

2. The method for preparing dust briquettes for front-end dust collection of a calcium carbide furnace according to claim 1, wherein in step S1, the amount of composite binder added is 5 to 10 wt% of the mass of the dust briquettes for front-end dust collection of the calcium carbide furnace.

3. The method for preparing dust briquettes for pre-furnace dust removal of a calcium carbide furnace according to claim 1, wherein the composite binder comprises the following components in parts by weight: 3-6 parts plant fiber, 8-10 parts dried plant stem powder, 0.1-0.3 parts polyacrylamide, 0.5-1.0 parts sodium silicate, and 0.4-0.8 parts bentonite.

4. The method for preparing dust ash briquettes for pre-furnace dust removal in a calcium carbide furnace according to claim 1, characterized in that, In step S2, the pressure molding includes pre-pressing, heat preservation treatment, and final pressing.

5. The method for preparing dust ash briquettes for pre-furnace dust removal in a calcium carbide furnace according to claim 1, characterized in that, In step S3, the mass ratio of green bulb embryo, nano-silica, ammonium bicarbonate and microcrystalline cellulose is 100:2~4:3~6:1~3.

6. The method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace according to claim 1, characterized in that, In step S3, γ-aminopropyltriethoxysilane is also added to the composite solution.

7. The method for preparing dust ash briquettes for pre-furnace dust removal in a calcium carbide furnace according to claim 6, characterized in that, The amount of γ-aminopropyltriethoxysilane added is 0.5 to 1.5 wt% of the weight of the green embryo.

8. The method for preparing dust ash briquettes for pre-furnace dust removal in a calcium carbide furnace according to claim 1, characterized in that, In step S4, the mass concentration of the silica sol solution is 4-8 wt%.

9. The method for preparing dust briquettes for pre-furnace dust removal in a calcium carbide furnace according to claim 1, characterized in that, In step S4, the solid content of the nano-alumina suspension is 7-10 wt%.

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