Fly ash-silicon-aluminum solid waste blending granulation and melting process

Abstract

The invention discloses a fly ash-silicon-aluminum solid waste blending granulation and melting process. The process comprises the following steps: S1, raw material pretreatment; s2, blending granulation: mixing the pretreated high-calcium fly ash, fly ash and waste glass powder, and granulating the mixture through a granulator; s3, melting treatment is conducted, specifically, the particles obtained in the step S2 are subjected to melting treatment, and molten slag is subjected to water quenching or air cooling to form a glassy-state solid; and S4, product treatment: cooling the glassy solid obtained in the step S3, and crushing to obtain product particles. Through the synergistic effect of the silicon-aluminum solid waste and the high-calcium fly ash, the melting temperature is reduced to 1000-1200 DEG C from the traditional 1300-1500 DEG C, so that the energy consumption can be obviously reduced; dioxin is thoroughly decomposed through high temperature of melting treatment, heavy metal is stably solidified in a vitreous body network, and a melting product is vitreous body aggregate with stable performance and can be directly subjected to high-value resource utilization.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solid waste recycling, in particular to a fly ash-silicon aluminum solid waste blending granulation and melting process. BACKGROUND

[0002] With the acceleration of urbanization, waste incineration has become one of the mainstream solid waste treatment methods, but the fly ash (especially high calcium fly ash) generated by it is rich in heavy metals, dioxins and other pollutants, and is listed in the National Hazardous Waste List (HW18), which needs to be strictly treated. At present, the mainstream disposal technology of fly ash includes cement kiln co-processing, chemical stabilization / solidification landfill and high-temperature melting treatment, but all have limitations: high calcium fly ash is easy to cause cement kiln skinning and affect clinker quality during cement kiln co-processing, and the amount of mixing needs to be controlled, so the resource utilization efficiency is low; chemical stabilization / solidification landfill needs to add a large amount of cement, chelating agent and other reagents, which is high in cost, and the long-term stability of the solidified body is insufficient, which has the risk of heavy metal leaching. On the other hand, the annual output of silicon aluminum industrial solid waste (such as fly ash and waste glass powder) is more than 1 billion tons, which is currently mainly used as a concrete filler material with low added value. SUMMARY

[0003] The purpose of the present application is to provide a fly ash-silicon aluminum solid waste blending granulation and melting process to solve the problems in the prior art.

[0004] In order to achieve the above-mentioned purpose, the technical scheme of the present application provides a fly ash-silicon aluminum solid waste blending granulation and melting process, which includes the following steps: S1, raw material pretreatment, magnetic separation of high calcium fly ash to remove iron and screening treatment to obtain high calcium fly ash powder, and crushing and ball milling treatment of fly ash and waste glass powder to obtain silicon aluminum solid waste powder; S2, blending granulation, mixing the pretreated high calcium fly ash, fly ash and waste glass powder in the following mass ratio: high calcium fly ash 50%-70%, fly ash 20%-35% and waste glass powder 10%-25%; the mixed material is granulated by a granulator; S3, melting treatment, the granules obtained in step S2 are subjected to melting treatment, and the molten slag after melting is formed into a glassy solid by water quenching or air cooling; S4, product treatment, the glassy solid obtained in step S3 is crushed after cooling to obtain product granules.

[0005] Further, in step S1, the high calcium fly ash screening treatment process uses a 100 mesh screen; the fly ash and waste glass powder crushing process uses a jaw crusher with an output particle size of ≤5mm, and the ball milling process uses a ball mill with an output particle size of ≤200 mesh.

[0006] Furthermore, in step S2, the SiO2 / Al2O3 molar ratio in the mixed powder is controlled at 2.0-4.0, and the Na2O+B2O3 content is controlled at 8%-15%; the mixing process in step S2 also includes an auxiliary agent, which is industrial-grade borax or soda ash.

[0007] Furthermore, in step S2, the granulation process yields columnar particles with a diameter of 5-15 mm and a length of 10-30 mm.

[0008] Furthermore, the specific process of step S3 is as follows: the particles obtained in step S2 are put into the melting treatment device and the temperature is maintained at 1000-1200℃; the particles stay in the furnace for ≥2h, and the slag obtained after melting is quenched by water or air-cooled to form a glassy solid.

[0009] Further, the specific process of step S2 granulation is as follows: S21, the pretreated high-calcium fly ash is fed into a high-speed shear mixer, and 70%-80% of the total water is added through an atomizing nozzle. Through high-speed shear mixing, the water is initially and uniformly adsorbed by the fly ash, forming a moist and loose agglomerate, and fly ash granulated powder is obtained; S22, fly ash, waste glass powder and additives are dry mixed to obtain a uniformly composed silicon-aluminum mixed powder; S23, granulation: the fly ash granulated powder obtained in step S21 and the silicon-aluminum mixed powder obtained in step S22 are mixed in proportion and then granulated. Water is added as a binder during the granulation process.

[0010] Furthermore, the specific steps of granulation in step S23 are as follows: the wet fly ash granulated powder obtained in step S21 and the dry silicon-aluminum mixed powder obtained in step S22 are fed together into the granulation device through a quantitative feeding device to form granule preforms; then they are fed into a screw extruder granulator, and the remaining 20%-30% of water is added during the extrusion process, and finally they are extruded into high-strength columnar granules.

[0011] This invention also discloses a pelletizing apparatus for realizing the above-mentioned pelletizing process. The pelletizing apparatus includes a pelletizing drum body, a drive motor, a reducer, and an inlet / outlet that cooperate with the pelletizing drum body. The pelletizing drum body includes a central rotating shaft, a primary stirring spiral blade assembly, an extrusion assembly, and a secondary stirring spiral blade assembly. The extrusion assembly includes an extrusion disc, a rear pushing spiral blade assembly, and a front cutting blade. The extrusion disc is fixed inside the drum and has a preset through hole. The central rotating shaft is located in the center of the drum. The rear pushing spiral blade assembly and the front cutting blade are fixed on the central rotating shaft on both sides of the extrusion disc and abut against the extrusion disc. The primary stirring spiral blade assembly and the secondary stirring spiral blade assembly are fixed on both sides of the extrusion assembly, wherein the rear pushing spiral blade assembly and the primary stirring spiral blade assembly are located at the feed end.

[0012] Compared with existing technologies, this invention utilizes the synergistic effect of Na2O and B2O3 components in silicon-aluminum solid waste with CaO and SiO2 in high-calcium fly ash to reduce the melting temperature from the traditional 1300-1500℃ to 1000-1200℃, significantly reducing energy consumption. Using silicon-aluminum solid waste to replace commercial fluxes (such as soda ash and fluorite) effectively reduces flux costs. The high temperature of the melting process completely decomposes dioxins, and heavy metals are stably solidified in the vitreous network, with leaching toxicity far below national standard limits. The melting product is a stable vitreous aggregate that can be directly utilized for high-value resource recovery, achieving closed-loop waste treatment.

[0013] In terms of specific processes, the segmented mixing and granulation process solves the problems of stratification, agglomeration, and uneven moisture distribution when mixing multiple heterogeneous materials, ensuring the uniformity of granulated components and the stability of particle strength, and guaranteeing the synchronicity and consistency of their reaction in the melting furnace. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the process flow of the present invention.

[0015] Figure 2 This is a partial explosion diagram of a particle embryo granulation device according to an embodiment of the present invention.

[0016] Figure 3 This is a partially enlarged schematic diagram of a particle embryo granulation device according to an embodiment of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention aims to provide a fly ash-silica aluminum solid waste blending granulation and melting process. By synergistically combining high-calcium fly ash and silica aluminum solid waste, the SiO2, Al2O3, Na2O, B2O3 and other components in the silica aluminum solid waste are used as natural fluxes to reduce the melting temperature of the system and reduce the amount of commercial flux used. At the same time, high-pressure granulation and pre-curing improve the material flowability. Combined with the high-temperature environment of the waste incinerator, synergistic melting is achieved. Finally, heavy metals are solidified in the glass and dioxins are decomposed. The product is used as building material aggregate or roadbed material, achieving the triple goals of "harmlessness - resource utilization - economy".

[0019] As attached Figure 1 As shown, the process involved in this invention includes the following steps: S1. Raw material pretreatment: high-calcium fly ash is subjected to magnetic separation to remove iron and screening to obtain high-calcium fly ash powder; fly ash and waste glass powder are crushed and ball-milled to obtain silicon-aluminum solid waste powder. Specifically, high-calcium fly ash originates from the bag filter of a waste incinerator, and its main components are CaO (20%-40%), SiO2 (15%-30%), Al2O3 (5%-15%), and Cl. - (2%-8%), magnetic separation iron removal rate >90%, screening process uses 100 mesh screen to remove large particulate impurities; Fly ash comes from coal-fired power plants, with SiO2+Al2O3≥70%; waste glass powder comes from glass recycling companies, with SiO2≥70% and Na2O+B2O3≥15%. The crushing process uses a jaw crusher with a discharge particle size ≤5mm, and the ball milling process uses a ball mill with a discharge particle size ≤200 mesh.

[0020] S2. Blending and granulation: The pretreated high-calcium fly ash, fly ash, and waste glass powder are mixed in the following mass ratio: 50%-70% high-calcium fly ash, 20%-35% fly ash, and 10%-25% waste glass powder; the mixed material is then granulated by a granulator.

[0021] More specifically, the SiO2 / Al2O3 molar ratio in the mixed powder is controlled at 2.0-4.0, and the Na2O+B2O3 content is controlled at 8%-15%. This is achieved by adjusting the proportions of high-calcium fly ash, fly ash, and waste glass powder within the above range. If the content of relevant components in fly ash or waste glass powder does not meet the requirement of Na2O+B2O3 content being 8%-15%, it is supplemented by adding additives, specifically industrial-grade borax (Na2B4O7·10H2O) or soda ash (Na2CO3).

[0022] More specifically, water is added as a binder during the granulation process, at a rate of 1.0%–3.0% of the total mass of the mixture. The added water is mainly used to activate the self-gelling properties of components such as CaO in the high-calcium fly ash. Furthermore, 0.1–0.3% of carboxymethyl cellulose can also be added as an organic binder.

[0023] More specifically, after granulation, columnar particles are prepared with a diameter of 5-15 mm, a length of 10-30 mm, and a drop strength (free fall from a height of 1 meter onto a steel plate) greater than 5 times.

[0024] Because high-calcium fly ash, fly ash, and waste glass powder exhibit significant differences in particle shape and density, stratification and segregation easily occur during mixing due to variations in density and particle size. Heavier or coarser particles settle to the bottom, while lighter or finer powders float, making it difficult to obtain a chemically homogeneous mixture. Uneven mixing leads to large fluctuations in the composition of the resulting particles. During melting, some particles may not melt completely due to insufficient flux, while others may over-melt due to excessive alkali metal content, resulting in uneven slagging within the furnace and severely impacting melting efficiency and product quality.

[0025] To address this problem, this application provides a segmented mixing and granulation process, specifically including the following steps: S21. The pretreated high-calcium fly ash is fed into a high-speed shear mixer, and 70%-80% of the total water is added through an atomizing nozzle. Through high-speed shear mixing, the water is initially and uniformly adsorbed by the fly ash, forming a moist and loose agglomerate, and fly ash granulated powder is obtained.

[0026] S22. Dry mix fly ash, waste glass powder, and additives to obtain a uniform silicon-aluminum mixed powder.

[0027] S23. Granulation: The fly ash granulated powder obtained in step S21 and the silicon-aluminum mixed powder obtained in step S22 are mixed in proportion and then granulated. During the granulation process, the remaining 20%-30% of water can be added.

[0028] The granulation process in step S23 is as follows: The moist fly ash granulated powder obtained in step S21 and the dry silica-alumina mixed powder obtained in step S22 are fed together into the pelletizing device via a quantitative feeding device. Under the rolling action of the rollers, the silica-alumina mixed powder and the fly ash granulated powder form pellets. Subsequently, the pellets are fed into a screw extruder, where the remaining 20%-30% of water is added during the extrusion process, and finally, they are extruded into high-strength columnar pellets.

[0029] To improve the uniformity of granulation of the granule embryo, as shown in the attached... Figure 2 As shown, this application also provides a pelletizing apparatus, which is a drum type and includes a primary mixing drum section and a secondary rounding drum section, with an extrusion section provided between the primary mixing drum section and the secondary rounding drum section.

[0030] Details are attached. Figure 2 As shown in Figure 3, the granulation drum body of the pellet pelletizing device includes a central rotating shaft 1, a primary stirring spiral blade assembly 2, an extrusion assembly 3, a secondary stirring spiral blade assembly 4, and a drum 5. The pellet pelletizing device also includes a drive motor, a reducer, inlet and outlet ports, and other components that cooperate with the granulation drum body. These components are conventional knowledge in the field.

[0031] The extrusion assembly 3 includes an extrusion disc 31, a rear-mounted feeding spiral blade assembly 32, and a front-mounted cutting blade 33. The extrusion disc 31 is fixed inside the roller 5. For ease of assembly, the roller 5 is a modular assembly, with the extrusion disc 31 positioned between the two parts. The extrusion disc 31 has pre-set through holes.

[0032] The central rotating shaft 1 is located in the center of the drum 5, with a rear-mounted pushing spiral blade assembly 32 and a front-mounted cutting blade 33 fixed on the central rotating shaft on both sides of the extrusion disc 31, abutting against the extrusion disc 31.

[0033] The front cutting blade 33 includes a rotating shaft fixing sleeve and two opposing cutting plates fixed on the rotating shaft fixing sleeve. The rear pushing spiral blade assembly 32 includes a spiral pushing blade assembly 321 and extrusion blades 322. The spiral pushing blade assembly 321 consists of spirally arranged blades with a pitch smaller than that of the primary stirring spiral blade assembly 2. The extrusion blades 322 include a rotating shaft fixing sleeve and several extrusion plates b arranged in a circumferential array on the rotating shaft fixing sleeve. The lower part of the extrusion plate b has a gap with the extrusion disk 3, and the upper part is inclined away from the extrusion disk 3, forming a space that is wider at the top and narrower at the bottom with the extrusion disk 3. During the rotation of the extrusion blades 322, the material gradually moves downward from the top of the extrusion plate b and is extruded from the extrusion disk 3.

[0034] The primary stirring spiral blade assembly 2 and the secondary stirring spiral blade assembly 4 are fixed on both sides of the extrusion assembly 3, wherein the rear pusher spiral blade assembly 32 and the primary stirring spiral blade assembly 2 are located at the feed end.

[0035] Furthermore, to improve the mixing effect of the materials, several lifting plates l1 are provided on the spiral blades of the primary stirring spiral blade assembly 2 and the secondary stirring spiral blade assembly 4. During rotation, the materials can be better dispersed in the drum. The lifting plates l1 are located on the side near the extrusion assembly 3. The lifting plates l1 protrude from the surface of the spiral blades and are arc-shaped.

[0036] S3. Melting treatment: The particles obtained in step S2 are melted, and the molten slag is quenched by water or air to form a glassy solid.

[0037] Specifically, the melting process is carried out in a waste incinerator. The particles obtained in step S2 are put into a melting treatment device and the temperature is maintained at 1000-1200℃. The particles stay in the furnace for ≥2 hours. The slag obtained after melting is quenched by water or air-cooled to form a glassy solid.

[0038] The melting device can be a rotary kiln melting furnace; the rotary kiln melting furnace adopts a gas combustion system or an electric heating system, and can use biogas produced by the waste incineration plant or externally supplied natural gas as fuel. Simultaneously, to minimize energy consumption, waste heat from the waste incineration plant can be used to preheat the particles. By controlling the rotation speed, inclination angle, and length of the rotary kiln, the particle residence time in the kiln is ensured to be ≥2 hours, and the kiln temperature is maintained at 1000-1200℃, thus completing the melting process.

[0039] During the melting process, SiO2 and Al2O3 in the silicon-aluminum solid waste react with CaO in the high-calcium fly ash to form low-melting-point silicates. Simultaneously, Na2O and B2O3 in the waste glass powder lower the liquidus temperature of the system (200-300℃ lower than that of pure high-calcium fly ash). Dioxins undergo high-temperature decomposition above 800℃ (decomposition rate > 99%), and heavy metals (Pb, Cd, etc.) react with Cl... - O 2- They combine to form stable chlorides (such as PbCl2) or are encapsulated in a glass network structure (curing rate > 98%).

[0040] S4. Product processing: The glassy solid obtained in step S3 is cooled and then crushed to obtain product particles.

[0041] Specifically, the product particles include coarse aggregate with a particle size of 5-20mm, mainly used for road base and concrete aggregate; and fine powder with a particle size of ≤5mm, mainly used for compounding with cement and sand to prepare recycled building materials (such as permeable bricks and blocks).

[0042] It should be noted that, unless otherwise explicitly specified and limited, terms such as "installation," "connection," "joining," "fixing," and "setting" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

Claims

1. A fly ash-silica-alumina solid waste blending, granulation, and melting process, characterized in that, The process includes the following steps: S1, raw material pretreatment, high-calcium fly ash is subjected to magnetic separation to remove iron and screening to obtain high-calcium fly ash powder, and fly ash and waste glass powder are crushed and ball-milled to obtain silicon-aluminum solid waste powder. S2. Blending and granulation: The pretreated high-calcium fly ash, fly ash, and waste glass powder are mixed in the following mass ratio: 50%-70% high-calcium fly ash, 20%-35% fly ash, and 10%-25% waste glass powder; the mixed material is then granulated using a granulator. S3. Melting treatment: The particles obtained in step S2 are melted, and the molten slag is quenched by water or air-cooled to form a glassy solid. S4. Product processing: The glassy solid obtained in step S3 is cooled and then crushed to obtain product particles.

2. The process according to claim 1, characterized in that, In step S1, the high-calcium fly ash screening process uses a 100-mesh screen; the fly ash and waste glass powder crushing process uses a jaw crusher with a discharge particle size ≤5mm; and the ball milling process uses a ball mill with a discharge particle size ≤200mesh.

3. The process according to claim 1, characterized in that, In step S2, the SiO2 / Al2O3 molar ratio in the mixed powder is controlled at 2.0-4.0, and the Na2O+B2O3 content is controlled at 8%-15%. The mixing process in step S2 also includes an auxiliary agent, which is industrial-grade borax or soda ash.

4. The process according to claim 3, characterized in that, In step S2, the granulation process yields columnar particles with a diameter of 5-15 mm and a length of 10-30 mm.

5. The process according to claim 1, characterized in that, The specific process of step S3 is as follows: The particles obtained in step S2 are put into the melting treatment device and the temperature is maintained at 1000-1200℃; the particles stay in the furnace for ≥2h, and the slag obtained after melting is quenched by water or air-cooled to form a glassy solid.

6. The process according to claim 4, characterized in that, The specific process of step S2 granulation is as follows: S21, the pretreated high-calcium fly ash is fed into a high-speed shear mixer, and 70%-80% of the total water is added through an atomizing nozzle. Through high-speed shear mixing, the water is initially and uniformly adsorbed by the fly ash, forming a moist and loose agglomerate, and fly ash granulated powder is obtained; S22, fly ash, waste glass powder and additives are dry mixed to obtain a uniformly composed silicon-aluminum mixed powder; S23, granulation: the fly ash granulated powder obtained in step S21 and the silicon-aluminum mixed powder obtained in step S22 are mixed in proportion and then granulated. Water is added as a binder during the granulation process.

7. The process according to claim 6, characterized in that, The specific steps of granulation in step S23 are as follows: The wet fly ash granulated powder obtained in step S21 and the dry silicon-aluminum mixed powder obtained in step S22 are fed together into the granulation device through a quantitative feeding device to form granule preforms; then they are fed into a screw extruder granulator, and the remaining 20%-30% of water is added during the extrusion process, and finally they are extruded into high-strength columnar granules.

8. A pelletizing apparatus for implementing the pelletizing process of claim 7, the pelletizing apparatus comprising a pelletizing drum body, a drive motor, a reducer, and inlet / outlet ports cooperating with the pelletizing drum body, characterized in that, The granulation drum body includes a central rotating shaft, a primary stirring spiral blade assembly, an extrusion assembly, and a secondary stirring spiral blade assembly. The extrusion assembly includes an extrusion disc, a rear pushing spiral blade assembly, and a front cutting blade. The extrusion disc is fixed inside the drum and has a preset through hole. The central rotating shaft is located in the center of the drum. The rear pushing spiral blade assembly and the front cutting blade are fixed on the central rotating shaft on both sides of the extrusion disc and abut against the extrusion disc. The primary stirring spiral blade assembly and the secondary stirring spiral blade assembly are fixed on both sides of the extrusion assembly, with the rear pushing spiral blade assembly and the primary stirring spiral blade assembly located at the feed end.

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