Environment-friendly brick drying and roasting method and system
By using a phased drying and firing method, the problems of unevenness and cracking in the drying and firing process of environmentally friendly bricks were solved, the yield and quality stability were improved, and the efficient production of environmentally friendly bricks was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-15
- Publication Date
- 2026-04-14
AI Technical Summary
Existing environmentally friendly bricks suffer from uneven drying, "false drying," over-firing, and under-firing during the drying and firing process. This leads to inconsistent shrinkage in different parts of the brick body, generating internal stress, which easily causes surface cracks, edge cracks, and deformation, reducing the yield.
A staged drying and firing method is adopted, including primary preheating, constant-rate drying, slow-rate drying, equilibrium drying and moisture detection, combined with secondary preheating, firing, heat preservation and cooling treatment in the firing kiln to ensure the uniformity of drying inside and outside the brick blank, and qualified bricks are screened through performance parameter testing.
This process ensures uniform drying of the environmentally friendly bricks both inside and out, preventing cracking and improving the yield rate. Furthermore, screening ensures the quality stability and performance of the bricks meet the standards.
Smart Images
Figure CN121850601A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of environmentally friendly brick technology, and in particular to an environmentally friendly brick drying and firing method and system. Background Technology
[0002] Eco-friendly bricks are made primarily from industrial waste such as fly ash, slag, and coal gangue. They are produced using processes like room-temperature mixing and room-temperature hardening, and are used to prepare new types of wall materials. The entire process does not involve high-temperature firing, significantly reducing reliance on traditional clay resources and damage to arable land, making them a key material for building sustainable building systems. Drying and firing are essential steps in the production of eco-friendly bricks. Specifically, drying, before firing, involves controlling the removal of most of the moisture from the brick blank, especially free and adsorbed water, thus laying the foundation for subsequent high-temperature firing. Firing, or sintering, is the decisive step that gives eco-friendly bricks their final "life." Through high-temperature heat, the loose mineral particles within the brick blank undergo a series of complex reactions, ultimately "sintering" into a solid whole.
[0003] However, existing environmentally friendly bricks often suffer from uneven drying and "false drying" (the surface of the brick appears dry, but the interior still contains high moisture content) during the drying and firing process. Furthermore, the firing process can involve both over-firing and under-firing, resulting in inconsistent shrinkage of different parts of the brick and generating enormous internal stress. When this stress exceeds the tensile strength that the brick itself can withstand, surface cracks, edge cracks, and even brick deformation will occur, thereby reducing the yield of the environmentally friendly bricks after drying and firing. Summary of the Invention
[0004] This application provides an environmentally friendly brick drying and firing method and system to solve the technical problems described in the background section.
[0005] To solve the above-mentioned technical problems, this application adopts the following technical solution: In a first aspect, this application provides a method for drying and firing environmentally friendly bricks, the method comprising: The extruded environmentally friendly brick blanks are conveyed from the feed inlet of the drying kiln into the drying kiln; The extruded environmentally friendly brick blanks are subjected to primary preheating, constant-rate drying, slow-rate drying, equilibrium drying, and moisture detection in the drying kiln to ensure that the moisture content of the environmentally friendly brick blanks is less than or equal to a first preset threshold, thereby obtaining the first environmentally friendly brick. The first environmentally friendly brick is transported into the firing kiln; The first environmentally friendly brick is subjected to two-stage preheating, firing, heat preservation and cooling treatment in the firing kiln to obtain the second environmentally friendly brick. The performance parameters of the second environmentally friendly brick are tested to obtain the performance parameter values of the second environmentally friendly brick. The performance parameter values are compared with a second preset threshold. When the performance parameter values are within the range of the second preset threshold, the second environmentally friendly brick is a qualified environmentally friendly brick; otherwise, the second environmentally friendly brick is an unqualified environmentally friendly brick.
[0006] Optionally, the environmentally friendly brick blank includes 60-80 parts by weight of coal gangue, 10-20 parts by weight of stripped soil, 20-30 parts by weight of fly ash, 5-15 parts by weight of red mud, 0.5-1.5 parts by weight of polypropylene fiber, and 2.5-3.5 parts by weight of nano-silica.
[0007] Optionally, the particle size of the coal gangue is ≤0.02mm.
[0008] Optionally, the coal gangue contains ≤5% calcium oxide, ≤2% magnesium oxide, and ≤0.6% sulfur.
[0009] Optionally, the temperature of the first-stage preheating is 40-60℃, the relative humidity of the first-stage preheating is 80-90%, and the time of the first-stage preheating is 2-3 hours. The constant-rate drying temperature is 70-90℃, the constant-rate drying relative humidity is 60-80%, and the constant-rate drying time is 8-12 hours. The temperature for the slow-drying process is 90-110℃, the relative humidity is 40-60%, and the drying time is 6-8 hours. The equilibrium drying temperature is 50-70℃, the relative humidity is 30-50%, and the equilibrium drying time is 2-3 hours.
[0010] Optionally, the first preset threshold is 4%-6%.
[0011] Optionally, the secondary preheating refers to preheating from room temperature to 550-650℃, and the secondary preheating time is 6-8 hours; The calcination temperature is 900-1050℃, and the calcination time is 4-6 hours; The insulation temperature is 1040-1060℃, and the insulation time is 2-3 hours; The cooling refers to cooling from the temperature during the heat preservation to 160-240℃, and the cooling time is 8-10 hours.
[0012] Optionally, the pressure of the secondary preheating is [-20, -10], and the pressure of the calcination is [5, 15]. The pressure unit for the secondary preheating and the pressure unit for the calcination are both Pa.
[0013] Secondly, this application provides an environmentally friendly brick drying and firing system, applied to any of the above-mentioned environmentally friendly brick drying and firing methods, comprising: A drying kiln, wherein a primary preheating chamber, a constant-speed drying chamber, a decreasing-speed drying chamber and a balanced drying chamber are arranged sequentially along its length. A first feed inlet is provided on the side wall of the primary preheating chamber away from the constant-speed drying chamber, and a first discharge outlet is provided on the side wall of the balanced drying chamber away from the decreasing-speed drying chamber. The drying kiln is used to sequentially preheat, dry at a constant speed, dry at a decreasing speed, and dry at a balanced speed through the primary preheating chamber, the constant speed drying chamber, the decreasing speed drying chamber, and the balanced drying chamber provided therein, thereby obtaining the first environmentally friendly brick. A moisture content detection device is provided on the outer wall of the drying chamber near the first discharge port. The device is used to detect the moisture content of the environmentally friendly brick blanks near the first discharge port in the balanced drying chamber to ensure that the moisture content of the first environmentally friendly bricks output from the first discharge port is less than or equal to a first preset threshold. A calcining kiln is located near the first discharge port, and a secondary preheating chamber, a calcining chamber, a heat preservation chamber, and a cooling chamber are arranged sequentially along its length. A second feed inlet is opened on the side wall of the secondary preheating chamber away from the calcining kiln, and a second discharge port is opened on the side wall of the cooling chamber away from the heat preservation chamber. The firing kiln is used to sequentially preheat, fire, heat-preserve, and cool the first environmentally friendly bricks that are output from the first discharge port and input into the kiln from the second inlet through the secondary preheating chamber, the firing chamber, the heat preservation chamber, and the cooling chamber provided therein, thereby obtaining the second environmentally friendly bricks.
[0014] Optionally, the drying kiln is provided with a heating medium inlet, and the roasting kiln is provided with a high-temperature flue gas outlet, the high-temperature flue gas outlet being connected to the heating medium inlet via a waste heat pipe; The waste heat pipe is equipped with an induced draft fan and an air volume regulating valve in sequence on the pipe body near the inlet of the heating medium.
[0015] 1) The environmentally friendly brick drying and firing method provided in this application involves sequentially performing primary preheating, constant-rate drying, slow-rate drying, equilibrium drying, and moisture detection on the extruded environmentally friendly brick blanks in a drying kiln. This ensures that the environmentally friendly brick blanks are dried as uniformly as possible, both internally and externally, after the primary preheating and three-stage drying process. The moisture content of the dried environmentally friendly brick blanks is then measured to ensure that the moisture content of the resulting first environmentally friendly brick is less than or equal to a first preset threshold. This ensures that the moisture content of the first environmentally friendly brick entering the firing kiln meets the requirements, thus avoiding problems such as cracking caused by uneven drying and high moisture content. Furthermore, by sequentially performing secondary preheating, firing, heat preservation, and cooling treatments on the first environmentally friendly brick in the firing kiln, continuous and stable staged firing is achieved during these four stages. This allows the moisture within the first environmentally friendly brick to gradually evaporate, resulting in the second environmentally friendly brick. This ensures the stability of the first environmentally friendly brick throughout the firing process, preventing cracking and improving the yield of the environmentally friendly bricks. In addition, by comparing the performance parameters of the second environmentally friendly brick with the second preset threshold, qualified and unqualified environmentally friendly bricks are screened out, thus realizing the screening of environmentally friendly bricks.
[0016] 2) The environmentally friendly brick drying and firing system provided in this application has a primary preheating chamber, a constant-rate drying chamber, a decreasing-rate drying chamber, and a balanced drying chamber arranged sequentially along its length in the drying kiln. The environmentally friendly brick blanks are preheated, dried at a constant rate, dried at a decreasing rate, and dried in a balanced manner through the primary preheating chamber, the constant-rate drying chamber, the decreasing-rate drying chamber, and the balanced drying chamber, so as to make the drying of the environmentally friendly brick blanks as uniform as possible. The moisture content of the dried environmentally friendly brick blanks is detected by a moisture content detection device to ensure that the moisture content of the first environmentally friendly bricks meets the requirements. This avoids problems such as cracking caused by uneven drying and high moisture content in the first environmentally friendly bricks. In addition, by sequentially setting up a secondary preheating chamber, a firing chamber, a heat preservation chamber, and a cooling chamber along its length in the firing kiln, and by sequentially preheating, firing, heat preservation, and cooling the first environmentally friendly brick through the aforementioned secondary preheating chamber, firing chamber, heat preservation chamber, and cooling chamber, continuous and stable staged firing is achieved. This allows the moisture in the first environmentally friendly brick to be gradually evaporated to obtain the second environmentally friendly brick, ensuring the stability of the first environmentally friendly brick throughout the firing process and avoiding cracking, thereby improving the yield of environmentally friendly bricks. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 This is a flowchart of an environmentally friendly brick drying and firing system provided in one embodiment of this application; Figure 2 This is a schematic diagram of the structure of an environmentally friendly brick drying and firing system provided in one embodiment of this application.
[0019] In the diagram: 100, Drying kiln; 101, Primary preheating chamber; 102, Constant-rate drying chamber; 103, Decreasing-rate drying chamber; 104, Balanced drying chamber; 200, Moisture content detection device; 300, Calcination kiln; 301, Secondary preheating chamber; 302, Calcination chamber; 303, Insulation chamber; 304, Cooling chamber; 400, Waste heat pipe; 401, Exhaust fan; 402, Air volume regulating valve. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application are described clearly and completely below. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are also within the scope of protection of this application.
[0021] In a first aspect, this application provides a method for drying and firing environmentally friendly bricks, the method comprising: The extruded environmentally friendly brick blanks are transported from the feed inlet of the drying kiln 100 into the drying kiln 100. The extruded environmentally friendly bricks are extruded by a JKY90y-4.0 type double-stage vacuum hard plastic extruder and stacked on the kiln car, and then transported into the drying kiln 100 by a traction machine.
[0022] The environmentally friendly brick blanks after extrusion molding are subjected to primary preheating, constant speed drying, slow speed drying, balanced drying and moisture detection in drying kiln 100 to ensure that the moisture content of the environmentally friendly brick blanks is less than or equal to a first preset threshold, thus obtaining the first environmentally friendly brick; among them, after primary preheating and three stages of drying, the internal and external drying of the environmentally friendly brick blanks is made as uniform as possible.
[0023] The first environmentally friendly brick is transported into the firing kiln 300; specifically, the first environmentally friendly brick is on the kiln car and transported into the firing kiln 300 by a tractor.
[0024] The first environmentally friendly brick is subjected to two-stage preheating, firing, heat preservation, and cooling treatments in a firing kiln 300 to obtain the second environmentally friendly brick. This process ensures continuous and stable staged firing of the first environmentally friendly brick throughout the four stages, allowing the moisture within the first brick to gradually evaporate and resulting in the second environmentally friendly brick. This process ensures the stability of the first environmentally friendly brick throughout the firing process, preventing cracking and improving the yield of the environmentally friendly bricks.
[0025] The performance parameters of the second environmentally friendly brick are tested to obtain the performance parameter values. The performance parameter values are compared with a second preset threshold. When the performance parameter values are within the range of the second preset threshold, the second environmentally friendly brick is a qualified environmentally friendly brick; otherwise, the second environmentally friendly brick is an unqualified environmentally friendly brick, thus realizing the screening of environmentally friendly bricks.
[0026] The environmentally friendly brick drying and firing method provided in this application involves sequentially performing primary preheating, constant-rate drying, slow-rate drying, equilibrium drying, and moisture detection on the extruded environmentally friendly brick blanks within a drying kiln 100. This ensures that the environmentally friendly brick blanks are dried as uniformly as possible, both internally and externally, after the primary preheating and three-stage drying process. The moisture content of the dried environmentally friendly brick blanks is measured to ensure that the moisture content is less than or equal to a first preset threshold. This guarantees that the moisture content of the first environmentally friendly bricks entering the firing kiln 300 meets the requirements, thus avoiding problems such as cracking caused by uneven drying or high moisture content. Furthermore, the firing kiln 300 sequentially performs secondary preheating, firing, heat preservation, and cooling treatments on the first environmentally friendly bricks. This allows for continuous and stable staged firing of the first environmentally friendly bricks during these four stages, gradually evaporating the moisture within them to obtain the second environmentally friendly bricks. This ensures the stability of the first environmentally friendly bricks throughout the firing process, preventing cracking and improving the yield of the finished environmentally friendly bricks. In addition, by comparing the performance parameters of the second environmentally friendly brick with the second preset threshold, qualified and unqualified environmentally friendly bricks are screened out, thus realizing the screening of environmentally friendly bricks.
[0027] In some embodiments, the environmentally friendly brick blank in this application comprises 60-80 parts by weight of coal gangue, 10-20 parts by weight of stripped soil, 20-30 parts by weight of fly ash, 5-15 parts by weight of red mud, 0.5-1.5 parts by weight of polypropylene fiber, and 2.5-3.5 parts by weight of nano-silica.
[0028] In the above embodiments, coal gangue is a complex rock mixture with SiO2 and Al2O3 as its main chemical components, similar to clay. Therefore, coal gangue can be used as a raw material for brick making. Furthermore, coal gangue typically contains a certain amount of residual carbon, allowing the carbon in the environmentally friendly brick blank containing coal gangue to burn and generate heat during the drying and firing process. This helps reduce the heat required for the drying and firing process, thereby reducing energy consumption and costs. The stripping soil, rich in clay minerals, has good plasticity and can improve the molding performance of the mixture. During sintering, it can fill the voids between coal gangue particles, forming a denser structure, resulting in higher strength in the dried and fired environmentally friendly bricks. Fly ash, rich in active SiO2 and Al2O3, is an excellent pozzolanic material. The small amount of fluxing oxides it contains (such as Fe2O3, CaO, K2O, and Na2O) can lower the sintering temperature of the system, broaden the sintering range, and save energy. Furthermore, during the calcination process, the active oxides in fly ash undergo solid-phase reactions with the oxides produced by the decomposition of coal gangue and stripped soil, generating high-strength mineral phases such as mullite and anorthite, thus significantly improving the compressive and flexural strength of the environmentally friendly bricks. Red mud, a strongly alkaline waste residue discharged during alumina production, primarily consists of Fe2O3, Al2O3, SiO2, and various alkaline oxides. The strongly alkaline environment of red mud effectively activates the pozzolanic activity of the glassy phase in fly ash and calcined coal gangue, promoting the formation of an aluminosilicate network structure. This chemical bonding effect significantly enhances the strength of the environmentally friendly bricks. Additionally, the abundant Na2O and other alkaline oxides in red mud act as excellent fluxes, further reducing the sintering temperature. Simultaneously, the high Fe2O3 content makes it a natural red colorant, imparting a uniform and aesthetically pleasing color to the environmentally friendly bricks. Nano-silica nanoparticles can further fill the tiny voids between raw material particles such as coal gangue and stripped soil, greatly improving the density and uniformity of the brick blank, and inducing the formation of hydration products or high-temperature sintering mineral phases, refining grains, thereby improving the microstructure of the material and significantly enhancing its macroscopic mechanical properties. Furthermore, the extremely high reactivity of nano-silica allows it to rapidly react with alkaline substances such as Ca(OH)2 in the system, generating a large amount of CSH gel, which can further enhance the compressive strength of the environmentally friendly brick. In the early stages of drying and sintering the brick blank, polypropylene fibers can form a randomly distributed network structure in three-dimensional space, effectively inhibiting the generation and propagation of microcracks, improving the toughness and impact resistance of the environmentally friendly brick, and leaving behind micropores corresponding to its morphology after firing. These pores facilitate the escape of water vapor from the environmentally friendly brick, reducing the risk of cracking during drying and firing.
[0029] In some embodiments, the coal gangue in this application has a particle size ≤0.02mm, which increases the specific surface area of the coal gangue particles, making them easier to form during the preparation of environmentally friendly bricks.
[0030] In some embodiments, the coal gangue in this application contains ≤5% calcium oxide, ≤2% magnesium oxide, and ≤0.6% sulfur by mass. The aforementioned calcium oxide, magnesium oxide, and sulfur may produce calcium sulfate and magnesium sulfate during the preparation of environmentally friendly bricks. Calcium sulfate and magnesium sulfate dissolve in water, potentially causing discoloration of the environmentally friendly bricks during use, resulting in unstable color. The above embodiments ensure that the calcium oxide content is ≤5%, the magnesium oxide content is ≤2%, and the sulfur content is ≤0.6%, resulting in environmentally friendly bricks with low levels of calcium sulfate and magnesium sulfate. Even when exposed to water, the color change of the environmentally friendly bricks is not significant, thus ensuring color stability.
[0031] In some embodiments, the primary preheating temperature in this application is 40-60℃, the relative humidity is 80-90%, and the preheating time is 2-3 hours. The extruded environmentally friendly brick blanks are wet blanks before entering the drying kiln 100. Therefore, after the extruded environmentally friendly brick blanks enter the drying kiln 100, the temperature is first slowly increased to vaporize the surface moisture, which is then carried away by the hot drying air. Subsequently, the moisture inside the brick blank moves towards the surface and vaporizes and is discharged. At this time, the discharged moisture is the free water between the brick blank particles. Due to the discharge of free water, adjacent particles quickly move closer together to occupy the free space, causing the blank to shrink. However, the drying of environmentally friendly brick blanks always proceeds gradually from the outer layer to the inner layer, with the outer layer shrinking faster and the inner layer shrinking slower. When the inner and outer shrinkages are inconsistent, internal stress is created. When the internal stress exceeds the elastic coefficient of the brick blank itself, drying cracks will occur. Therefore, the temperature of the environmentally friendly brick blanks should not be increased too quickly during the primary preheating stage, and the main task of the primary preheating stage is to increase the temperature, not to dehydrate. The temperature of the first-stage preheating is 40-60℃, the relative humidity of the first-stage preheating is 80-90%, and the first-stage preheating time is 2-3 hours. This allows the environmentally friendly brick blanks to be gradually preheated to a temperature close to the constant-rate drying temperature, thus avoiding the risk of cracking of the environmentally friendly brick blanks during the subsequent drying and heating process.
[0032] The temperature for constant-rate drying is 70-90℃, the relative humidity is 60-80%, and the drying time is 8-12 hours. During this stage, the brick blanks are dehydrated without heating, and the stability of the drying process is ensured within the above-mentioned range.
[0033] The temperature for falling-rate drying is 90-110℃, the relative humidity is 40-60%, and the drying time is 6-8 hours. At the end of the constant-rate drying stage, the free water inside the environmentally friendly brick blank has been largely drained, and drying shrinkage is essentially complete. At this point, the adsorbed water coating the particle surface begins to evaporate. However, the evaporation of adsorbed water requires overcoming the adsorption force on the particle surface, making its evaporation process more difficult than that of free water. Under the same conditions, the drying rate is significantly slowed down, and the drying shrinkage process essentially stops. Therefore, compared to constant-rate drying, increasing the temperature and decreasing the humidity during falling-rate drying can accelerate the drying rate of the environmentally friendly brick blank.
[0034] The equilibrium drying temperature is 50-70℃, the relative humidity is 30-50%, and the equilibrium drying time is 2-3 hours. The purpose of equilibrium drying is to ensure that the residual moisture in the environmentally friendly brick blanks and the moisture in the drying air within the drying kiln reach equilibrium, preventing further evaporation of moisture from the brick blanks and maintaining a stable moisture level. This ensures the stability of the first batch of environmentally friendly bricks after drying.
[0035] In some embodiments, the first preset threshold in this application is 4%-6%.
[0036] In the above embodiments, if the drying process is excessive, the surface of the first environmentally friendly brick will become very hard and brittle. When the first environmentally friendly brick enters the firing kiln, the outer layer expands and contracts due to the increased temperature, while the inner layer remains at a relatively low temperature (not fully heated), resulting in a large temperature difference between the inner and outer layers. This can cause the first environmentally friendly brick to crack or break during the heating phase in the firing kiln. However, in the above embodiments, the first preset threshold is 4%-6%, which allows the first environmentally friendly brick to retain a certain amount of moisture and possess a certain degree of plasticity. This allows the thermal expansion process of the first environmentally friendly brick during firing to proceed relatively uniformly and stably, thereby reducing the risk of cracking or breaking of the first environmentally friendly brick blank.
[0037] In some embodiments, the secondary preheating in this application refers to preheating from room temperature to 550-650°C for 6-8 hours; the calcination temperature is 900-1050°C for 4-6 hours; the holding temperature is 1040-1060°C for 2-3 hours; and the cooling refers to cooling from the holding temperature to 160-240°C for 8-10 hours.
[0038] In the above embodiments, by sequentially performing secondary preheating, firing, heat preservation and cooling on the first environmentally friendly brick blank within the above parameter range, the chemical reaction of the first environmentally friendly brick blank in the firing kiln is fully carried out, and the structure of the second environmentally friendly brick blank is made dense and uniform, thereby improving the overall strength of the second environmentally friendly brick blank.
[0039] In some embodiments, the pressure of the secondary preheating in this application is [-20, -10], and the pressure of calcination is [5, 15]; wherein the pressure unit of the secondary preheating and the pressure unit of calcination are both Pa.
[0040] In the above embodiments, the pressure of the secondary preheating is negative and within [-20, -10], resulting in a relatively high airflow velocity during the secondary preheating process, making heat transfer more efficient. It also removes some heat, preventing the environmentally friendly bricks from drying or deforming prematurely due to excessively high temperatures during the secondary preheating process. The firing pressure is positive and within [5, 15], resulting in a relatively slower airflow velocity. Heat remains more fully within the firing zone, and the firing process is where the actual chemical reaction (such as vitrification) occurs in the brick blank. Positive pressure prolongs the residence time of the gas in this area, ensuring that the brick blank receives sufficient heat for thorough sintering, thereby improving the sintering efficiency of the environmentally friendly bricks. The following embodiments further illustrate the invention in detail. However, it should be understood that the embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0041] Example 1
[0042] The drying and firing method for environmentally friendly brick blanks in this embodiment includes the following steps: S101. The extruded environmentally friendly brick blanks are conveyed from the feed inlet of the drying kiln 100 into the drying kiln 100.
[0043] The aforementioned environmentally friendly brick blanks include 60 parts by weight of coal gangue, 20 parts by weight of stripped soil, 20 parts by weight of fly ash, 15 parts by weight of red mud, 0.5 parts by weight of polypropylene fiber, and 3.5 parts by weight of nano-silica.
[0044] S102. The environmentally friendly brick blanks after extrusion molding are subjected to primary preheating, constant speed drying, slow speed drying, equilibrium drying and moisture detection in the drying kiln 100 so that the moisture content of the environmentally friendly brick blanks is less than or equal to the first preset threshold, and the first environmentally friendly brick is obtained.
[0045] The temperature for the first-stage preheating is 50℃, the relative humidity is 85%, and the preheating time is 2 hours; the temperature for constant-rate drying is 80℃, the relative humidity is 70%, and the drying time is 12 hours; the temperature for falling-rate drying is 110℃, the relative humidity is 60%, and the drying time is 8 hours; the temperature for equilibrium drying is 70℃, the relative humidity is 50%, and the drying time is 3 hours.
[0046] S103. The first environmentally friendly brick is transported into the firing kiln 300.
[0047] S104. The first environmentally friendly brick is subjected to two-stage preheating, firing, heat preservation and cooling treatment in a firing kiln 300 to obtain the second environmentally friendly brick.
[0048] The above-mentioned two-stage preheating refers to preheating from room temperature to 650℃ for 8 hours; the calcination temperature is 1000℃ for 6 hours; the holding temperature is 1050℃ for 3 hours; and the cooling refers to cooling from the holding temperature to 240℃ for 10 hours. The pressure for the two-stage preheating is -8 Pa, and the pressure for calcination is 10 Pa.
[0049] Example 2
[0050] The drying and firing method for environmentally friendly brick blanks in this embodiment includes the following steps: S201. The extruded environmentally friendly brick blanks are conveyed from the feed inlet of the drying kiln 100 into the drying kiln 100.
[0051] The aforementioned environmentally friendly brick blanks include 80 parts by weight of coal gangue, 10 parts by weight of stripped soil, 30 parts by weight of fly ash, 5 parts by weight of red mud, 1.5 parts by weight of polypropylene fiber, and 2.5 parts by weight of nano-silica.
[0052] S202. The environmentally friendly brick blanks after extrusion molding are subjected to primary preheating, constant speed drying, slow speed drying, equilibrium drying and moisture detection in the drying kiln 100 so that the moisture content of the environmentally friendly brick blanks is less than or equal to the first preset threshold, and the first environmentally friendly brick is obtained.
[0053] The temperature for the first-stage preheating is 50℃, the relative humidity is 85%, and the preheating time is 2 hours; the temperature for constant-rate drying is 80℃, the relative humidity is 70%, and the drying time is 12 hours; the temperature for falling-rate drying is 110℃, the relative humidity is 60%, and the drying time is 8 hours; the temperature for equilibrium drying is 70℃, the relative humidity is 50%, and the drying time is 3 hours.
[0054] S203. The first environmentally friendly brick is transported into the firing kiln 300.
[0055] S204. The first environmentally friendly brick is subjected to two-stage preheating, firing, heat preservation and cooling treatment in a firing kiln 300 to obtain the second environmentally friendly brick.
[0056] The above-mentioned two-stage preheating refers to preheating from room temperature to 650℃ for 8 hours; the calcination temperature is 1000℃ for 6 hours; the holding temperature is 1050℃ for 3 hours; and the cooling refers to cooling from the holding temperature to 240℃ for 10 hours. The pressure for the two-stage preheating is -8 Pa, and the pressure for calcination is 10 Pa.
[0057] Example 3
[0058] The drying and firing method for environmentally friendly brick blanks in this embodiment includes the following steps: S301. The extruded environmentally friendly brick blanks are conveyed from the feed inlet of the drying kiln 100 into the drying kiln 100.
[0059] The aforementioned environmentally friendly brick blanks contain 73 parts by weight of coal gangue, 14 parts by weight of stripped soil, 26 parts by weight of fly ash, 11 parts by weight of red mud, 0.7 parts by weight of polypropylene fiber, and 3 parts by weight of nano-silica.
[0060] S302. The environmentally friendly brick blanks after extrusion molding are subjected to primary preheating, constant speed drying, slow speed drying, equilibrium drying and moisture detection in the drying kiln 100 so that the moisture content of the environmentally friendly brick blanks is less than or equal to the first preset threshold, and the first environmentally friendly brick is obtained.
[0061] The temperature for the first-stage preheating is 50℃, the relative humidity is 85%, and the preheating time is 2 hours; the temperature for constant-rate drying is 80℃, the relative humidity is 70%, and the drying time is 12 hours; the temperature for falling-rate drying is 110℃, the relative humidity is 60%, and the drying time is 8 hours; the temperature for equilibrium drying is 70℃, the relative humidity is 50%, and the drying time is 3 hours.
[0062] S303, The first environmentally friendly brick is transported into the firing kiln 300.
[0063] S304. The first environmentally friendly brick is subjected to two-stage preheating, firing, heat preservation and cooling treatment in the firing kiln 300 to obtain the second environmentally friendly brick.
[0064] The above-mentioned two-stage preheating refers to preheating from room temperature to 650℃ for 8 hours; the calcination temperature is 1000℃ for 6 hours; the holding temperature is 1050℃ for 3 hours; and the cooling refers to cooling from the holding temperature to 240℃ for 10 hours. The pressure for the two-stage preheating is -8 Pa, and the pressure for calcination is 10 Pa.
[0065] Comparative Example 1 The drying and firing method for environmentally friendly brick blanks in this embodiment includes the following steps: The difference from Example 3 is that the environmentally friendly brick blank in S101 includes 73 parts by weight of coal gangue and 14 parts by weight of stripped soil.
[0066] Comparative Example 2 The difference from Example 3 is that the environmentally friendly brick blank in S101 includes 73 parts by weight of coal gangue, 14 parts by weight of stripped soil, 26 parts by weight of fly ash and 11 parts by weight of red mud.
[0067] Comparative Example 3 The difference from Example 3 is that the environmentally friendly brick blank in S101 includes 73 parts by weight of coal gangue, 14 parts by weight of stripping soil, 0.7 parts by weight of polypropylene fiber and 3 parts by weight of nano silica.
[0068] The compressive strength, flexural strength, and water absorption of Examples 1, 3, 1, 2, and 3, as well as Comparative Examples 1, 2, and 3, were tested according to the standard GB / T 5101-2017 for sintered common bricks. Three parallel tests were conducted for each test group, and the average value was taken. The test results are shown in Table 1. Table 1
[0069] As shown in Table 1 above, comparing Comparative Examples 2 and 3 with Comparative Example 1 reveals that the addition of fly ash and red mud, as well as polypropylene fiber and nano-silica, can enhance the compressive and flexural strength of the second environmentally friendly brick and reduce its water absorption rate. Comparing Comparative Examples 2 and 3 shows that the addition of polypropylene fiber and nano-silica significantly reduces the water absorption rate of the second environmentally friendly brick. Comparing Comparative Examples 2 and 3 with Example 3 shows that the combined addition of fly ash, red mud, polypropylene fiber, and nano-silica greatly improves the compressive and flexural strength of the second environmentally friendly brick and significantly reduces its water absorption rate. Furthermore, comparing Comparative Examples 2 and 3 with Example 1, and comparing Comparative Examples 2 and 3 with Example 2, it can be seen that compared to adding only fly ash and red mud or only polypropylene fiber and nano silica to the base of coal gangue and stripped soil, the environmentally friendly bricks, under the combined effect of fly ash, red mud, polypropylene fiber, and nano silica with coal gangue and stripped soil, have significantly improved tensile strength and flexural strength, while significantly reducing water absorption. In other words, during the drying and firing process, the environmentally friendly brick blanks, formed by extruding coal gangue, stripped soil, fly ash, red mud, polypropylene fiber, and nano-silica, undergo a solid-phase reaction between the active oxides in the fly ash and the oxides produced by the decomposition of coal gangue and stripped soil. This reaction generates high-strength mineral phases such as mullite and anorthite, which significantly improves the compressive and flexural strength of the environmentally friendly bricks. Furthermore, the highly alkaline environment of the red mud effectively activates the pozzolanic activity of the glassy phases in the fly ash and calcined coal gangue, promoting the formation of aluminosilicate network structures. This chemical bonding effect significantly enhances the strength of the environmentally friendly bricks. During the initial drying and sintering stages of the brick blank, polypropylene fibers can form a randomly distributed network structure in three-dimensional space, effectively inhibiting the generation and propagation of microcracks, improving the toughness and impact resistance of the environmentally friendly brick. After firing, they leave behind micropores corresponding to their morphology, which facilitate the escape of water vapor from the brick. Furthermore, the extremely high reactivity of nano-silica allows it to rapidly react with alkaline substances such as Ca(OH)2 in the system, generating a large amount of CSH gel, which further enhances the compressive strength of the environmentally friendly brick. Therefore, through the synergistic effect of the above components, the compressive strength and flexural strength of the second environmentally friendly brick are improved, while its water absorption rate is reduced.
[0070] Secondly, refer to Figure 1 and Figure 2 This application provides an environmentally friendly brick drying and firing system, applied to the aforementioned environmentally friendly brick drying and firing method, comprising: The drying kiln 100 has a primary preheating chamber 101, a constant-speed drying chamber 102, a decreasing-speed drying chamber 103, and a balanced drying chamber 104 arranged sequentially along its length. The primary preheating chamber 101 has a first feed inlet on its side wall away from the constant-speed drying chamber 102, and the balanced drying chamber 104 has a first discharge outlet on its side wall away from the decreasing-speed drying chamber 103. The first feed inlet is equipped with a first hydraulic jack. The extruded environmentally friendly brick blanks are usually stacked on the kiln car and pulled to the first feed inlet by a traction machine. The first feed inlet is then pushed into the primary preheating chamber 101 by the hydraulic jack.
[0071] The drying kiln 100 is used to preheat, dry at a constant speed, dry at a decreasing speed and dry at a balanced speed in sequence through a primary preheating chamber 101, a constant speed drying chamber 102, a decreasing speed drying chamber 103 and a balanced drying chamber 104, which are set inside the kiln, thereby obtaining the first environmentally friendly brick; wherein, the first environmentally friendly brick on the kiln car is pulled from the first discharge port to the transfer car by a traction machine.
[0072] A moisture content detection device 300 is installed on the outer wall of the drying kiln 100 near the first discharge port. It is used to detect the moisture content of the environmentally friendly brick blanks near the first discharge port in the equilibrium drying chamber 104 to ensure that the moisture content of the first environmentally friendly bricks output from the first discharge port is less than or equal to a first preset threshold. The first preset threshold is any value between 4% and 6%. This ensures that the internal stress generated by the shrinkage of the first environmentally friendly bricks during the firing process is less than its tensile strength, thereby preventing surface cracks, edge cracks, and even deformation of the blanks, thus improving the yield of the environmentally friendly bricks. The moisture content detection device 300 can be a resistance / capacitive moisture meter. Furthermore, when the moisture content of the first environmentally friendly bricks is greater than or equal to the first preset threshold, the drying time, relative humidity, and drying temperature parameters of the primary preheating chamber 101, constant-rate drying chamber 102, falling-rate drying chamber 103, and equilibrium drying chamber 104 are adjusted to ensure that the moisture content of the first environmentally friendly bricks meets the requirements.
[0073] The firing kiln 300 is located near the first discharge port, and inside it, along its length, are arranged a secondary preheating chamber 301, a firing chamber 302, a heat preservation chamber 303, and a cooling chamber 304. A second feed inlet is opened on the side wall of the secondary preheating chamber 301 away from the firing chamber 302, and a second discharge port is opened on the side wall of the cooling chamber 304 away from the heat preservation chamber 303. The first environmentally friendly bricks on the kiln car are transported to the vicinity of the second feed inlet by a shuttle car, and a second hydraulic jack is installed on the second feed inlet. The second hydraulic jack pushes the kiln car and the first environmentally friendly bricks on it into the firing kiln 300 through the second feed inlet.
[0074] The firing kiln 300 is used to sequentially preheat, fire, heat-preserve, and cool the first environmentally friendly bricks, which are discharged from the first discharge port and fed into the kiln from the second inlet, through a secondary preheating chamber 301, a firing chamber 302, a heat preservation chamber 303, and a cooling chamber 304, thereby obtaining the second environmentally friendly bricks. The first environmentally friendly bricks on the kiln car are designated as the second environmentally friendly bricks after firing, and the second environmentally friendly bricks on the kiln car are pulled out from the second discharge port by a traction machine.
[0075] The environmentally friendly brick drying and firing system provided in this application comprises a primary preheating chamber 101, a constant-rate drying chamber 102, a decreasing-rate drying chamber 103, and a balanced drying chamber 104 arranged sequentially along its length within a drying kiln 100. These chambers sequentially achieve preheating, constant-rate drying, decreasing-rate drying, and balanced drying of the environmentally friendly brick blanks, ensuring uniform drying both internally and externally. A moisture content detection device 300 monitors the moisture content of the dried environmentally friendly brick blanks to ensure the moisture content of the resulting first environmentally friendly brick meets requirements. This avoids problems such as cracking caused by uneven drying and high moisture content in the first environmentally friendly brick. In addition, by sequentially arranging a secondary preheating chamber 301, a firing chamber 302, a heat preservation chamber 303, and a cooling chamber 304 along its length within the firing kiln 300, and by sequentially preheating, firing, heat preservation, and cooling the first environmentally friendly brick through the aforementioned secondary preheating chamber 301, firing chamber 302, heat preservation chamber 303, and cooling chamber 304, continuous and stable staged firing is achieved. This allows the moisture in the first environmentally friendly brick to gradually evaporate, resulting in the second environmentally friendly brick. This ensures the stability of the first environmentally friendly brick throughout the firing process, avoids cracking, and thus improves the yield of environmentally friendly bricks.
[0076] In some embodiments, reference Figure 2 The drying kiln 100 in this application is provided with a heating medium inlet, and the roasting kiln 300 is provided with a high-temperature flue gas outlet. The high-temperature flue gas outlet is connected to the heating medium inlet through a waste heat pipe 400. This realizes the reuse of the preheated flue gas generated in the roasting kiln 300 during the roasting process, thereby reducing the drying cost of the drying kiln.
[0077] Among them, the waste heat pipe 400 is equipped with an induced draft fan 401 and an air volume regulating valve 402 in sequence on the pipe body near the heating medium inlet.
[0078] In the above embodiment, the flue gas generated during the roasting process in the roasting kiln 300 is drawn through the waste heat pipe 400 to the heating medium inlet on the drying kiln 100 by the induced draft fan 401 to provide the heat required for the drying process in the drying kiln 100. The opening of the air volume regulating valve 402 is adjusted in real time according to the temperature inside the drying kiln 100 to regulate the flow rate of flue gas entering the waste heat pipe 400, thereby achieving precise temperature control inside the drying kiln.
[0079] It should be noted that temperature sensors are installed in the primary preheating chamber 101, constant speed drying chamber 102, falling speed drying chamber 103, and balanced drying chamber 104 in the drying kiln 100, so as to monitor the temperature in the primary preheating chamber 101, constant speed drying chamber 102, falling speed drying chamber 103, and balanced drying chamber 104 in real time.
[0080] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A method for drying and firing environmentally friendly bricks, characterized in that, The method includes: The extruded environmentally friendly brick blanks are conveyed from the feed inlet of the drying kiln into the drying kiln; The extruded environmentally friendly brick blanks are subjected to primary preheating, constant-rate drying, slow-rate drying, equilibrium drying, and moisture detection in the drying kiln to ensure that the moisture content of the environmentally friendly brick blanks is less than or equal to a first preset threshold, thereby obtaining the first environmentally friendly brick. The first environmentally friendly brick is transported into the firing kiln; The first environmentally friendly brick is subjected to two-stage preheating, firing, heat preservation and cooling treatment in the firing kiln to obtain the second environmentally friendly brick. The performance parameters of the second environmentally friendly brick are tested to obtain the performance parameter values of the second environmentally friendly brick. The performance parameter values are compared with a second preset threshold. When the performance parameter values are within the range of the second preset threshold, the second environmentally friendly brick is a qualified environmentally friendly brick; otherwise, the second environmentally friendly brick is an unqualified environmentally friendly brick.
2. The method for drying and firing environmentally friendly bricks according to claim 1, characterized in that, The environmentally friendly brick blank comprises 60-80 parts by weight of coal gangue, 10-20 parts by weight of stripped soil, 20-30 parts by weight of fly ash, 5-15 parts by weight of red mud, 0.5-1.5 parts by weight of polypropylene fiber, and 2.5-3.5 parts by weight of nano-silica.
3. The method for drying and firing environmentally friendly bricks according to claim 2, characterized in that, The particle size of the coal gangue is ≤0.02mm.
4. The method for drying and firing environmentally friendly bricks according to claim 2, characterized in that, The coal gangue contains ≤5% calcium oxide, ≤2% magnesium oxide, and ≤0.6% sulfur by mass.
5. The method for drying and firing environmentally friendly bricks according to claim 1, characterized in that, The temperature of the first-stage preheating is 40-60℃, the relative humidity of the first-stage preheating is 80-90%, and the time of the first-stage preheating is 2-3 hours. The constant-rate drying temperature is 70-90℃, the constant-rate drying relative humidity is 60-80%, and the constant-rate drying time is 8-12 hours. The temperature for the slow-drying process is 90-110℃, the relative humidity is 40-60%, and the drying time is 6-8 hours. The equilibrium drying temperature is 50-70℃, the relative humidity is 30-50%, and the equilibrium drying time is 2-3 hours.
6. The method for drying and firing environmentally friendly bricks according to claim 1, characterized in that, The first preset threshold is 4-6%.
7. The method for drying and firing environmentally friendly bricks according to claim 1, characterized in that, The secondary preheating refers to preheating from room temperature to 550-650℃, and the secondary preheating time is 6-8 hours; The calcination temperature is 900-1050℃, and the calcination time is 4-6 hours; The insulation temperature is 1040-1060℃, and the insulation time is 2-3 hours; The cooling refers to cooling from the temperature during the heat preservation to 160-240℃, and the cooling time is 8-10 hours.
8. The method for drying and firing environmentally friendly bricks according to claim 1, characterized in that, The pressure of the secondary preheating is [-20, -10], and the pressure of the calcination is [5, 15]. The pressure unit for the secondary preheating and the pressure unit for the calcination are both Pa.
9. An environmentally friendly brick drying and firing system, characterized in that, The method for drying and firing environmentally friendly bricks according to any one of claims 1 to 8 includes: A drying kiln, wherein a primary preheating chamber, a constant-speed drying chamber, a decreasing-speed drying chamber and a balanced drying chamber are arranged sequentially along its length. A first feed inlet is provided on the side wall of the primary preheating chamber away from the constant-speed drying chamber, and a first discharge outlet is provided on the side wall of the balanced drying chamber away from the decreasing-speed drying chamber. The drying kiln is used to sequentially preheat, dry at a constant speed, dry at a decreasing speed, and dry at a balanced speed through the primary preheating chamber, the constant speed drying chamber, the decreasing speed drying chamber, and the balanced drying chamber provided therein, thereby obtaining the first environmentally friendly brick. A moisture content detection device is provided on the outer wall of the drying chamber near the first discharge port. The device is used to detect the moisture content of the environmentally friendly brick blanks near the first discharge port in the balanced drying chamber to ensure that the moisture content of the first environmentally friendly bricks output from the first discharge port is less than or equal to a first preset threshold. A calcining kiln is located near the first discharge port, and a secondary preheating chamber, a calcining chamber, a heat preservation chamber, and a cooling chamber are arranged sequentially along its length. A second feed inlet is opened on the side wall of the secondary preheating chamber away from the calcining chamber, and a second discharge port is opened on the side wall of the cooling chamber away from the heat preservation chamber. The firing kiln is used to sequentially preheat, fire, heat-preserve, and cool the first environmentally friendly bricks that are output from the first discharge port and input into the kiln from the second inlet through the secondary preheating chamber, the firing chamber, the heat preservation chamber, and the cooling chamber provided therein, thereby obtaining the second environmentally friendly bricks.
10. The environmentally friendly brick drying and firing system according to claim 9, characterized in that, The drying kiln is provided with a heating medium inlet, and the roasting kiln is provided with a high-temperature flue gas outlet. The high-temperature flue gas outlet is connected to the heating medium inlet through a waste heat pipe. The waste heat pipe is equipped with an induced draft fan and an air volume regulating valve in sequence on the pipe body near the inlet of the heating medium.