Lightweight high-strength sintered ceramsite based on multi-source solid waste and preparation method of lightweight high-strength sintered ceramsite

Abstract

The invention belongs to the technical field of solid waste resource utilization, and relates to lightweight high-strength sintered ceramsite based on multi-source solid waste and a preparation method of the lightweight high-strength sintered ceramsite. Comprising the following steps: grinding and screening the oil sludge pyrolysis residues; mixing the treated mixture of the oil sludge pyrolysis residues, the fly ash and the coal gangue with municipal sludge; granulating the mixed materials to prepare raw material balls; carrying out gradient heating on the raw material nodules, and carrying out sintering treatment; and cooling the sintered product to obtain the sintered expanded ceramsite. According to the invention, the resource utilization of various solid wastes is realized, and on the premise of not adding any binder, the light high-strength sintered expanded ceramsite with excellent performance is stably prepared through wide-temperature-range sintering under the synergistic effect of multiple components.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource utilization, and relates to a light high-strength expanded ceramsite based on multi-source solid waste and a preparation method thereof. BACKGROUND

[0002] At present, with the continuous expansion of the petrochemical industry, urban sewage treatment and coal-fired power industry, the amount of various solid wastes generated has increased sharply, and their safe disposal and resource utilization have become a key problem restricting the green development of the industry.

[0003] Oily sludge is an important hazardous waste generated in the process of oilfield development, storage and transportation, and refining. With the continuous expansion of the oil industry, the amount of various oily sludge continues to increase. Its composition is complex, usually containing residual oil, heavy metals, sulfides and pathogenic microorganisms and other pollutants, and if not properly disposed of, it can cause serious harm to the environment and human health. In recent years, oil sludge pyrolysis technology has gradually become one of the mainstream treatment methods because it can realize the recovery of oil and the complete decomposition of pollutants. This technology indirectly heats the oily sludge under anaerobic conditions, allowing the organic components to be gasified and separated, but the pyrolysis residue still contains some oil and heavy metals, and is in the form of fine particles, which can easily be dispersed. The traditional disposal method is mainly landfill, which not only occupies land resources, but also poses environmental risks, and it is urgent to develop a resourceful and harmless disposal approach.

[0004] Municipal sludge is a large amount of by-product generated in the process of sewage treatment, with high water content, easy to rot, and containing pathogenic microorganisms and heavy metals and other pollutants. With the expansion of the sewage treatment scale, the sludge production has increased sharply, and the treatment cost has accounted for 20% to 50% of the total operating cost of the sewage treatment plant. How to achieve its reduction, stabilization and resource utilization has become the focus of the industry.

[0005] Fly ash is the main solid waste discharged by coal-fired power plants. Large-scale storage not only occupies land, but also poses risks of dust and heavy metal leaching. Although fly ash is rich in active components such as SiO2 and Al2O3 and has certain cementitious potential, it can partially replace clay raw materials, but at present, the high-value utilization approach is still limited.

[0006] Ceramsite, as a kind of lightweight and high-strength artificial aggregate, is widely used in building materials, filter materials and lightweight aggregate concrete fields. However, the traditional ceramsite production process mainly relies on natural mineral resources such as clay and shale, and large-scale mining leads to ecological environment destruction. In recent years, some studies have attempted to use oil sludge, municipal sludge and other solid wastes to replace part of the raw materials to prepare ceramsite. For example, Chinese patents CN111196731A and CN112919879A both disclose ceramsite production methods using oil-containing sludge or municipal sludge as the main raw material, but there are still obvious limitations: on the one hand, in order to ensure the forming and sintering performance of the green balls, a considerable proportion of kaolin, bentonite or chemical binder still needs to be added, which not only increases the cost, but also goes against the original intention of full utilization of solid waste; on the other hand, the existing process generally faces problems such as low green ball strength, narrow sintering temperature range and large product performance fluctuations. Especially for oil sludge pyrolysis residue, a dangerous waste, the existing technology has not yet realized its large-scale, safe and stable immobilization and resource utilization.

[0007] Therefore, it is of great significance to develop a method for preparing lightweight and high-strength ceramsite in a wide temperature range by using multi-source solid waste as the only raw material without adding external binder, which can break through the existing bottleneck of pyrolysis residue disposal and promote the collaborative resource utilization of solid waste. SUMMARY

[0008] In order to solve the problems in the prior art, the present application provides a lightweight and high-strength expanded ceramsite based on multi-source solid waste and a preparation method thereof, which realizes the resource utilization of various solid wastes and stably prepares lightweight and high-strength expanded ceramsite with excellent performance in a wide temperature range without adding any binder.

[0009] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, the present application provides a preparation method of lightweight and high-strength expanded ceramsite based on multi-source solid waste, comprising the following steps: Grinding and screening the oil sludge pyrolysis residue; Mixing the treated oil sludge pyrolysis residue, a mixture of fly ash and coal gangue, and municipal sludge; Granulating the mixed materials to obtain green balls; Gradient heating the green balls and performing sintering treatment; Cooling the sintered product to obtain the expanded ceramsite.

[0010] Preferably, the mass ratio of the treated oil sludge pyrolysis residue, the mixture of fly ash and coal gangue, and the municipal sludge is (25-40):(40-55):(15-30).

[0011] Preferably, the mass ratio of fly ash to coal gangue is (5.5~4):1.

[0012] Preferably, the step of gradient heating comprises: heating at 100~200℃ for 15~20min; heating at 400~600℃ for 10~15min.

[0013] Preferably, the moisture content of the green ball after gradient heating is <3%.

[0014] Preferably, the step of sintering comprises: heating from 800℃ to 1100℃ at a heating rate of 8℃ / min; heating from 1100℃ to 1175~1205℃ at a heating rate of 5~8℃ / min; heating from 1175~1205℃ to 1180~1210℃ at a heating rate of 5℃ / min, and holding at 1180~1210℃ for 1~8min.

[0015] Preferably, the step of cooling comprises: cooling to 800℃ at a cooling rate of 3~5℃ / min; then cooling from 800℃ to room temperature at a cooling rate of 8~10℃ / min.

[0016] Preferably, the oil content of the treated oil sludge pyrolysis residue is ≤2%, and the particle size range is 80~100 mesh.

[0017] Preferably, the mixture of fly ash and coal gangue is subjected to magnetic separation treatment before mixing.

[0018] In the second aspect, the application provides a lightweight high-strength expanded ceramic based on multi-source solid waste.

[0019] Compared with the prior art, the application has the following beneficial effects: The preparation method provided by the application realizes efficient preparation of lightweight high-strength expanded ceramsite through multi-source solid waste collaborative treatment and precise process control. Specifically, the oil sludge pyrolysis residue is sieved and ground to optimize the particle size distribution and reaction activity, and ensure uniform carbon residue foaming; then the mixture of oil sludge pyrolysis residue, fly ash and coal gangue is mixed with municipal sludge to fully exert the synergistic effect of oil sludge pyrolysis residue on fluxing and foaming, the mixture of fly ash and coal gangue on regulating melt viscosity and crystal phase generation, and sludge on providing organic foaming agent and granulation moisture; gradient heating and sintering are adopted to accurately control the kinetics process of organic matter decomposition, gas release, liquid phase formation and mullite crystal precipitation, and finally the expanded ceramsite with low density, high strength, low water absorption and high porosity is successfully prepared, the whole process does not need to add binder, and the organic combination of solid waste resource utilization and high-performance building material production is realized. DETAILED DESCRIPTION

[0020] To enable those skilled in the art to understand the features and effects of the present application, the following is a general description and definition of the terms and phrases mentioned in the specification and claims. Unless otherwise specified, all technical and scientific words used herein have their usual meanings to those skilled in the art of the present application, and in case of conflict, the definition in the specification shall prevail.

[0021] Theories or mechanisms described and disclosed herein, whether correct or not, should not be considered limiting the scope of the present application, i.e., the present application can be practiced without any particular theory or mechanism.

[0022] In this text, all features defined in the form of numerical range or percentage range such as numerical value, quantity, content and concentration are only for the sake of brevity and convenience. Therefore, the description of numerical range or percentage range should be considered to have covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0023] In this text, unless otherwise specified, "comprise", "include", "contain", "have" or similar terms cover the meaning of "consist of" and "consist essentially of", for example, "A comprises a" covers the meaning of "A comprises a and other" and "A only comprises a".

[0024] In this text, for the sake of brevity, all possible combinations of various technical features in each embodiment or example are not described. Therefore, as long as the combinations of technical features do not conflict, any combination of technical features in each embodiment or example can be combined, and all possible combinations should be considered as the scope disclosed in the specification.

[0025] The first object of the present application is to provide a preparation method of lightweight high-strength expanded ceramsite based on multi-source solid waste, which realizes efficient utilization of solid waste resources and optimization of ceramsite performance through the synergistic effect of oil sludge pyrolysis residue, a mixture of fly ash and coal gangue, and municipal sludge, comprising the following steps: S1, grinding and screening treatment is performed on the oil sludge pyrolysis residue; the mixture of fly ash and coal gangue is subjected to magnetic separation treatment, and the coal gangue is subjected to grinding treatment before mixing and screening with a sieve of more than 200 meshes.

[0026] The oil sludge pyrolysis residue is ground and screened to control its particle size (80-100 meshes) and ensure that the oil content is ≤2%, ensuring uniform distribution of residual carbon in the oil sludge pyrolysis residue and avoiding the influence of fuel oil residues on product performance; at the same time, the mixture of fly ash and coal gangue is subjected to magnetic separation treatment, which can selectively remove magnetic substances such as Fe2O3 with strong fluxing effect, and by adjusting the Fe2O3 content of the mixture, it can avoid the premature formation of excessive low-viscosity liquid phase during sintering, which can cause deformation or collapse of the ceramsite, thereby effectively widening the sintering temperature window and enhancing the process stability and product consistency.

[0027] S2, the treated oil sludge pyrolysis residue, the mixture of fly ash and coal gangue, and the municipal sludge are mixed in a mass ratio of (25-40):(40-55):(15-30); wherein the mass ratio of fly ash to coal gangue is (5.5-4):1.

[0028] The residual carbon (2%-5%) in the oil sludge pyrolysis residue and the organic matter in the sludge together form a dual foaming system, which significantly improves the porosity of the ceramsite through synergistic gas production; the fluxing components such as Fe2O3 (5%-8%) and CaO (3%-8%) can effectively reduce the formation temperature of silicate melt and reduce the sintering energy consumption; at the same time, the inherent micron-sized porous structure of the oil sludge pyrolysis residue provides an initial pore basis for the ceramsite, which is conducive to gas accumulation and uniform pore development. Municipal sludge with a water content of 65%-82% can be directly used as a source of water for granulation, significantly reducing the additional water consumption, and the organic matter (proteins, lipids, etc.) in the sludge can generate CO2, H2, etc. during the pyrolysis process, which can effectively build the porous structure of the ceramsite as a foaming agent; in addition, the humic acid remaining in the sludge and the residual carbon in the oil sludge pyrolysis residue form a synergistic effect, which can reduce the liquid phase viscosity of the silicate melt during high-temperature sintering, promote uniform gas escape and pore development, and thus synergistically realize the lightweight and strength optimization of the ceramsite.

[0029] By introducing calcined coal gangue and fly ash to form a composite system, the crystal composition and sintering temperature window of the ceramsite are significantly optimized: 3Al2O3 2SiO2) as the main crystalline phase of high-temperature sintering, which endows the ceramsite with high melting point, high hardness and excellent mechanical properties; fly ash provides active SiO2 and Al2O3 to react with CaO to form a liquid phase layer with moderate viscosity, while coal gangue not only increases the Al2O3 content to promote the full formation of mullite, but also contains TiO2 (1%~3%) as a nucleating agent to induce the directional precipitation of mullite crystals, further improving the compressive strength. The widening of the temperature window is due to multiple regulation: the fluxing effect of TiO2 and Fe2O3 in coal gangue forms a gradient melting zone at about 1100℃, while reducing the Fe2O3 content (removal rate 50%) through magnetic separation pretreatment can avoid premature liquid phase formation or too low viscosity, while increasing the Al2O3 content to increase the liquid phase viscosity and mullite crystal supportability, and inhibit high-temperature flow deformation. Experiments show that the sintering window of pure fly ash system is only 1170±10℃ (fluctuation >±5℃ leads to underfiring or overfiring), while the system with calcined coal gangue expands the window to 1150~1220℃, and the cylinder pressure strength fluctuation is <15% within ±10℃, significantly improving the process stability and product consistency.

[0030] S3, granulating the mixed material to prepare φ10~20mm green balls, and the water content of the green balls is controlled at 18%~22%.

[0031] The present application can not only make full use of the water content in municipal sludge itself to reduce external water addition, but also ensure that the green balls have appropriate plasticity and mechanical strength to meet the requirements of the subsequent sintering process on the integrity of the body; if the mixed material has poor hand balling due to component fluctuations, a small amount of water can be added to adjust the water content to the optimal range, thereby ensuring the stability and consistency of the green ball forming quality, laying a foundation for uniform expansion and structure optimization in the subsequent high-temperature sintering stage.

[0032] S4, gradient heating and sintering treatment are performed on the green balls, so that the water content of the green balls after gradient heating is <3%.

[0033] The gradient heating step includes: heating at 100~200℃ for 15~20min; heating at 400~600℃ for 10~15min.

[0034] The present application first removes free water and part of bound water at a low temperature stage (100~200℃) to avoid cracking of the body caused by rapid evaporation of water, and then completely decomposes the organic matter in the sludge and stabilizes the carbonaceous components at a medium temperature stage (400~600℃) to reserve gas sources for subsequent foaming.

[0035] The sintering step comprises: heating from 800 DEG C to 1100 DEG C at a heating rate of 8 DEG C / min; heating from 1100 DEG C to 1175 DEG C to 1205 DEG C at a heating rate of 5 DEG C / min to 8 DEG C / min; heating from 1175 DEG C to 1205 DEG C to 1180 DEG C to 1210 DEG C at a heating rate of 5 DEG C / min, and keeping at 1180 DEG C to 1210 DEG C for 1 min to 8 min.

[0036] In the main foaming stage at 800 DEG C to 1100 DEG C, the rapid heating at 8 DEG C / min promotes the pyrolysis of sludge organic matter to generate CO2 and a small amount of CH4 gas; in the secondary foaming stage from 1100 DEG C to the target temperature (1180 DEG C to 1210 DEG C), the slow heating at 5 DEG C / min to 8 DEG C / min promotes the reduction reaction of residual carbon in the pyrolysis residue and Fe2O3 (3C+Fe2O3→2Fe+3CO↑) to generate CO gas for continuous expansion of the pore. At the same time, the metakaolin (Al6Si2O 13 ) generated by the decomposition of coal gangue and the unburned carbon in the pyrolysis residue form a synergistic effect (Al6Si2O 13 +C→3Al2O3+2SiO2+CO2↑) to compensate for the decay of the decomposition rate of sludge organic matter and maintain the pore generation power. On the other hand, by adjusting the viscosity of the silicate melt, it can effectively wrap the gas; finally, the short-time holding at 1180 DEG C to 1210 DEG C optimizes the crystal phase development, cooperatively controls the dynamic balance of the gas release rate and the melt solidification process, and promotes the liquid phase to completely wrap the bubbles to form an independent closed pore structure during the cooling stage, thereby constructing a ceramsite microsystem with high porosity and high strength.

[0037] S5, cooling the sintered product to obtain the expanded ceramsite.

[0038] The cooling step comprises: cooling at a cooling rate of 3 DEG C / min to 5 DEG C / min to 800 DEG C, and then cooling from 800 DEG C to room temperature at a cooling rate of 8 DEG C / min to 10 DEG C / min.

[0039] The slow cooling in the high-temperature section (above 800 DEG C) effectively avoids the coarsening of mullite crystals, the accumulation of internal stress in the glass phase and the generation of macroscopic cracks due to sudden temperature drop, ensuring the mechanical strength of the ceramsite; the fast cooling in the medium-low temperature section (below 800 DEG C) inhibits the excessive crystallization or secondary shrinkage of the residual liquid phase, reducing the formation of open pore structure, thereby significantly reducing the water absorption of the ceramsite and stabilizing its lightweight and high-strength closed pore microstructure.

[0040] The ceramsite prepared by the method of the present application, the heavy metals possibly existing in the oil sludge residue are also wrapped by the molten glass phase at high temperature to form a stable silicate structure, and the leaching toxicity is far lower than the relevant solid waste identification standard; at the same time, in the preheating and sintering stages, the residual oil in the pyrolysis residue is completely decomposed / burned.

[0041] The second object of the present application is to provide a lightweight high-strength expanded ceramic based on multi-source solid waste, the cylinder compressive strength of which is kept in a high-strength interval of 7.3-8.1 MPa (better than the 600-grade ceramic particles of the national standard GB / T17431.1-2010), the bulk density of which is in the lightweight range of 592-721 kg / m 3 The second object of the present application is to provide a lightweight high-strength expanded ceramic based on multi-source solid waste, the cylinder compressive strength of which is kept in a high-strength interval of 7.3-8.1 MPa (better than the 600-grade ceramic particles of the national standard GB / T17431.1-2010), the bulk density of which is in the lightweight range of 592-721 kg / m

[0042] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not used to limit the scope of the present application. Furthermore, it should be understood that those skilled in the art can make various modifications or changes to the present application after reading the content taught by the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0043] The following examples use the conventional apparatus in the art. The experimental methods in the following examples, if not specified, are usually carried out according to the conventional conditions, or according to the conditions suggested by the manufacturers. The following examples use various raw materials, unless otherwise specified, all use the conventional commercially available products, and the specifications are the conventional specifications in the art. In the specification of the present application and the following examples, unless otherwise specified, "%" means weight percent, "parts" means weight parts, and the ratio means weight ratio.

[0044] The individual component proportions of the oil sludge pyrolysis residue, fly ash, coal gangue and municipal sludge selected in the embodiments of the present application are shown in Table 1: Table 1 Individual component proportions of oil sludge pyrolysis residue, fly ash, coal gangue and municipal sludge

[0045] Example 1 The oil sludge pyrolysis residue is ground and sieved to control the particle size to 80 mesh; the coal gangue is ground and sieved using a 200 mesh sieve to obtain coal gangue powder; 5 parts of fly ash and 1 part of coal gangue powder are uniformly mixed, and the mixture is subjected to magnetic separation by a magnetic roller; The treated oil sludge pyrolysis residue, the mixture of fly ash and coal gangue after magnetic separation, and municipal sludge (water content 65%) are mixed in a mass ratio of 3:5:2, uniformly mixed with water, and then granulated to obtain φ10 mm green balls; the water content of the green balls is 21.2%, and the strength is >70 N; Put the green balls into the first muffle furnace, keep at 150℃ for 15min, then put into the second muffle furnace, keep at 500℃ for 10min, ensure the water content of the green balls <3%; Preheat the green balls at a heating rate of 8℃ / min from 800℃ to 1100℃, then at a heating rate of 8℃ / min from 1100℃ to 1205℃, finally at a heating rate of 5℃ / min from 1205℃ to 1210℃, and keep at 1210℃ for 4min; Cool to 800℃ at a cooling rate of 5℃ / min, then cool to room temperature at a cooling rate of 8℃ / min from 800℃, to obtain the expanded ceramic.

[0046] The cylinder compressive strength of the expanded ceramic is 8.1Mpa, the bulk density is 692kg / m 3 , the 1h water absorption is 5.54%, the porosity is 71%, and the surface is vitrified.

[0047] Example 2 Grind and screen the oil sludge pyrolysis residue to control the particle size to be 80 mesh; grind the coal gangue and screen it with a 200 mesh sieve to obtain coal gangue powder; uniformly mix 5 parts of fly ash and 1 part of coal gangue powder, and magnetically separate the mixture by a magnetic roller; Mix the treated oil sludge pyrolysis residue, the mixture of fly ash and coal gangue after magnetic separation, and municipal sludge (water content 65%) according to a mass ratio of 2.5:4.5:3, mix uniformly, and granulate to obtain φ10mm green balls; the water content of the green balls is 19.6%, and the strength is >60N; Put the green balls into the first muffle furnace, keep at 150℃ for 20min, then put into the second muffle furnace, keep at 500℃ for 10min, ensure the water content of the green balls <3%; Preheat the green balls at a heating rate of 8℃ / min from 800℃ to 1100℃, then at a heating rate of 8℃ / min from 1100℃ to 1175℃, finally at a heating rate of 5℃ / min from 1175℃ to 1180℃, and keep at 1180℃ for 4min; Cool to 800℃ at a cooling rate of 6℃ / min, then cool to room temperature at a cooling rate of 8℃ / min from 800℃, to obtain the expanded ceramic.

[0048] The cylinder compressive strength of the expanded ceramic is 7.3Mpa, the bulk density is 606kg / m 3 , the 1h water absorption is 6.56%, the porosity is 76%, and the surface is liquefied and expanded.

[0049] Example 3 The oil sludge pyrolysis residue is ground and screened to control the particle size to be 90 mesh; the coal gangue is ground and screened by a 250 mesh sieve to obtain coal gangue powder; 5 parts of fly ash and 1 part of coal gangue powder are uniformly mixed, and the mixed material is subjected to magnetic separation by a magnetic roller; The treated oil sludge pyrolysis residue, the mixture of fly ash and coal gangue after magnetic separation, and municipal sludge (water content 65%) are mixed in a mass ratio of 3:5:2, uniformly mixed with water, and then granulated to obtain φ15mm green balls; the water content of the green balls is 21.2%, and the strength is >70N; The green balls are placed into a first muffle furnace, kept at 150℃ for 15min, then placed into a second muffle furnace, kept at 500℃ for 10min, to ensure that the water content of the green balls is <3%; The preheated green balls are heated from 800℃ to 1100℃ at a heating rate of 8℃ / min, then heated from 1100℃ to 1175℃ at a heating rate of 8℃ / min, and finally heated from 1175℃ to 1180℃ at a heating rate of 5℃ / min, and kept at 1180℃ for 3min; The temperature is decreased to 800℃ at a cooling rate of 7℃ / min, and then cooled from 800℃ to room temperature at a cooling rate of 9℃ / min to obtain the expanded ceramsite.

[0050] The test results show that the compressive strength of the expanded ceramsite is 7.9Mpa, the bulk density is 721kg / m 3 , the 1h water absorption is 7.98%, the porosity is 69%, and the surface is vitrified.

[0051] Example 4 The oil sludge pyrolysis residue is ground and screened to control the particle size to be 100 mesh; the coal gangue is ground and screened by a 300 mesh sieve to obtain coal gangue powder; 5 parts of fly ash and 1 part of coal gangue powder are uniformly mixed, and the mixed material is subjected to magnetic separation by a magnetic roller; The treated oil sludge pyrolysis residue, the mixture of fly ash and coal gangue after magnetic separation, and municipal sludge (water content 65%) are mixed in a mass ratio of 2.5:4.5:3, and then granulated to obtain φ20mm green balls; the water content of the green balls is 19.6%, and the strength is >60N; The green balls are placed into a first muffle furnace, kept at 150℃ for 20min, then placed into a second muffle furnace, kept at 500℃ for 10min, to ensure that the water content of the green balls is <3%; The preheated green balls are heated from 800℃ to 1100℃ at a heating rate of 8℃ / min, then heated from 1100℃ to 1205℃ at a heating rate of 8℃ / min, and finally heated from 1205℃ to 1210℃ at a heating rate of 5℃ / min, and kept at 1210℃ for 2min; The temperature is lowered to 800°C at a rate of 8°C / min, and then cooled from 800°C to room temperature at a rate of 10°C / min to obtain the sintered ceramsite.

[0052] The tested sintered ceramsite showed a compressive strength of 8.1 MPa and a bulk density of 592 kg / m³. 3 The water absorption rate is 4.02% in 1 hour, the porosity is 77%, and the surface liquefies and expands.

[0053] Example 5 The pyrolysis residue of oily sludge is ground and sieved to control its particle size to 100 mesh; the coal gangue is ground and sieved through a 300 mesh sieve to obtain coal gangue powder; 5.5 parts of fly ash and 1 part of coal gangue powder are mixed evenly, and the mixture is magnetically separated by a magnetic drum. The treated oil sludge pyrolysis residue, the mixture of magnetically separated fly ash and coal gangue, and municipal sludge (moisture content 65%) were mixed at a mass ratio of 4:4:2. After adding water and mixing evenly, the mixture was granulated to obtain φ20mm raw material balls; the raw material balls had a moisture content of 18% and a strength >60N. The raw material pellets are placed in the first muffle furnace and held at 100°C for 20 minutes, then placed in the second muffle furnace and held at 600°C for 10 minutes, ensuring that the moisture content of the raw material pellets is <3%. The preheated raw material pellets were heated from 800℃ to 1100℃ at a heating rate of 8℃ / min, then from 1100℃ to 1190℃ at a heating rate of 5℃ / min, and finally from 1190℃ to 1195℃ at a heating rate of 5℃ / min, and held at 1195℃ for 8 minutes. The temperature is lowered to 800°C at a rate of 8°C / min, and then cooled from 800°C to room temperature at a rate of 10°C / min to obtain the sintered ceramsite.

[0054] Example 6 The pyrolysis residue of oily sludge is ground and sieved to control its particle size to 100 mesh; the coal gangue is ground and sieved through a 300 mesh sieve to obtain coal gangue powder; 4 parts fly ash and 1 part coal gangue powder are mixed evenly, and the mixture is magnetically separated by a magnetic drum. The treated oil sludge pyrolysis residue, the mixture of magnetically separated fly ash and coal gangue, and municipal sludge (moisture content 65%) were mixed at a mass ratio of 3:5.5:1.5. After adding water and mixing evenly, the mixture was granulated to obtain φ20mm raw material balls; the raw material balls had a moisture content of 22% and a strength >60N. The raw material pellets are placed in the first muffle furnace and held at 200°C for 15 minutes, then placed in the second muffle furnace and held at 400°C for 15 minutes, ensuring that the moisture content of the raw material pellets is <3%. The preheated raw material balls are heated from 800 DEG C to 1100 DEG C at a heating rate of 8 DEG C / min, then heated from 1100 DEG C to 1200 DEG C at a heating rate of 6 DEG C / min, finally heated from 1200 DEG C to 1205 DEG C at a heating rate of 5 DEG C / min, and kept at 1205 DEG C for 1 min; cooled to 800 DEG C at a cooling rate of 8 DEG C / min, then cooled from 800 DEG C to room temperature at a cooling rate of 10 DEG C / min, to obtain the sintered expanded ceramic.

[0055] In summary, the sintered expanded ceramic prepared by the present application has excellent comprehensive performance: the cylinder compressive strength of the samples in Examples 1-4 is kept in the high strength range of 7.3-8.1 MPa, the bulk density is in the lightweight range of 592-721 kg / m 3 The 1-hour water absorption rate is less than 8%, the porosity is in the range of 65%-80%, and the surface realizes good vitrification or liquid expansion, which indicates that by adjusting the raw material ratio, particle size, sintering and cooling system, the lightweight high-strength sintered expanded ceramic with low density, high strength and low water absorption is successfully prepared from multiple solid wastes without adding a binder, and the process repeatability and product stability are good.

[0056] The above is only the preferred embodiment of the present application and is not used to limit the present application, and for those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste, characterized in that, Includes the following steps: The pyrolysis residue of oil sludge is ground and sieved. The treated oil sludge pyrolysis residue, fly ash and coal gangue mixture and municipal sludge are mixed together; The mixed materials are granulated to obtain raw material pellets; The raw material balls are subjected to gradient heating and sintering. The sintered product is cooled to obtain the sintered ceramic particles.

2. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The mass ratio of the treated oil sludge pyrolysis residue, fly ash and coal gangue mixture and municipal sludge is (25~40):(40~55):(15~30).

3. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The mass ratio of fly ash to coal gangue is (5.5~4):

1.

4. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The gradient heating step includes: Heat at 100–200℃ for 15–20 minutes; Heat at 400–600℃ for 10–15 minutes.

5. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 4, characterized in that, The moisture content of the raw material pellets after gradient heating is <3%.

6. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The sintering step includes: The temperature was increased from 800℃ to 1100℃ at a heating rate of 8℃ / min; The temperature was increased from 1100℃ to 1175~1205℃ at a heating rate of 5~8℃ / min; The temperature was increased from 1175~1205℃ to 1180~1210℃ at a heating rate of 5℃ / min, and held at 1180~1210℃ for 1~8min.

7. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The cooling step includes: Cool to 800℃ at a cooling rate of 3~5℃ / min; Then cool to room temperature at a rate of 8~10℃ / min.

8. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The treated pyrolysis residue has an oil content of ≤2% and a particle size range of 80~100 mesh.

9. The method for preparing lightweight, high-strength sintered ceramsite based on multi-source solid waste according to claim 1, characterized in that, The mixture of fly ash and coal gangue is subjected to magnetic separation before mixing.

10. A lightweight, high-strength sintered ceramsite based on multi-source solid waste, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 9.

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