Environment-friendly shale brick based on multi-source waste and preparation method thereof

Abstract

This invention discloses an environmentally friendly shale brick based on multi-source waste and its preparation method. Using shale as the matrix, it is compounded with fine powder from construction waste, sludge incineration ash, waste ceramic powder, and rice husk charcoal. Simultaneously, calcined kaolin, red mud, silane coupling agent, calcium stearate, sodium carboxymethyl cellulose, polyvinyl alcohol, and sodium lignosulfonate are introduced to form a composite system of "inorganic solid waste + mineral reinforcement + organic modification + low-temperature segmented sintering." The organic components play a role in plasticizing, binding, water retention, and crack reduction during the green body stage. They completely pyrolyze at high temperatures without residue and do not affect mineral phase formation. In synergy with the inorganic system, the green body achieves crack-free construction, extremely low shrinkage, and significantly improved strength.

Description

Technical Field

[0001] This invention relates to the field of building material preparation technology, and in particular to an environmentally friendly shale brick based on multi-source waste and its preparation method. Background Technology

[0002] Shale bricks, as an important category of wall materials, have advantages such as high strength, good durability, and convenient construction, and are widely used in construction projects. Traditional shale brick production uses shale as the main raw material, relying on high-temperature sintering of clay minerals to form a dense structure. However, this method has problems such as high raw material consumption, high firing temperature, high energy consumption, and high carbon emissions. At the same time, single shale raw materials are prone to defects such as uneven shrinkage, cracking, and difficulty in controlling porosity during the firing process, affecting the finished product qualification rate and performance.

[0003] With the acceleration of urbanization and the expansion of industrial and agricultural production, the output of multi-source solid waste, such as construction waste, municipal sludge incineration ash, waste ceramics, and agricultural waste, has been increasing year by year. The large-scale accumulation of waste not only occupies land resources but also easily causes environmental risks such as dust and heavy metal leaching. Using these wastes in shale brick production can achieve solid waste reduction and resource utilization, lower shale brick production costs, and align with the development direction of green building materials. While existing technologies include research on incorporating single or two types of waste into shale bricks, they generally suffer from problems such as low waste content, insufficient synergistic effects, and limited performance improvement. Some technologies, due to poor matching of waste components, easily lead to shale bricks with low strength, excessive water absorption, and large drying shrinkage; some technologies still use high-temperature firing processes, failing to effectively reduce energy consumption; and most studies have not systematically considered the synergistic control mechanism of different wastes on the forming, sintering, pore structure, and durability of shale bricks, making it difficult for product stability to meet the requirements of high-standard projects.

[0004] Furthermore, existing shale brick production processes mostly employ direct mixing and single-stage sintering, failing to optimize aging and firing regimes for the characteristics of multi-source waste. This easily leads to problems such as uneven material mixing, internal stress concentration, and incomplete sintering, resulting in significant fluctuations in product performance. Simultaneously, the lack of systematic comparative and standardized experimental data makes it difficult to demonstrate the creativity and stability of the technical solutions, thus limiting their industrial-scale application.

[0005] Therefore, developing an environmentally friendly shale brick preparation method that is adaptable to multi-source waste, has a scientifically designed formula, optimized process, excellent performance, and meets national standards, and achieves the dual goals of efficient utilization of solid waste and improved building material performance, has significant engineering value and environmental benefits. Summary of the Invention

[0006] In view of this, the purpose of this invention is to overcome the shortcomings of the prior art and provide an environmentally friendly shale brick based on multi-source waste and its preparation method. The environmentally friendly shale brick has higher compressive strength, lower water absorption, less drying shrinkage, higher finished product qualification rate, large solid waste content, energy saving, environmental protection and safety and non-toxicity.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An environmentally friendly shale brick based on multi-source waste comprises the following raw materials by weight: 60-75 parts shale, 8-15 parts fine powder of construction waste, 5-10 parts sludge incineration ash, 4-8 parts waste ceramic powder, 2-5 parts rice husk charcoal, 2-4 parts calcined kaolin powder, 1-3 parts red mud powder, 0.1-0.3 parts silane coupling agent, 0.2-0.5 parts calcium stearate, 1-3 parts composite mineralizer, 0.1-0.3 parts sodium carboxymethyl cellulose, 0.05-0.15 parts polyvinyl alcohol, 0.1-0.2 parts sodium lignosulfonate, and 12-18 parts water.

[0008] Preferably, the construction waste powder is a mixture of waste concrete and waste mortar, with a particle size ≤0.15mm.

[0009] Preferably, the sludge incineration ash is the ash residue from dewatered sludge from a municipal wastewater treatment plant after incineration at 600-700℃, with a total SiO2+Al2O3 content ≥65%.

[0010] Preferably, the waste ceramic powder is a grinding powder of waste daily-use ceramics and building ceramics, with a Mohs hardness ≥ 6.5.

[0011] Preferably, the rice husk charcoal is obtained by carbonizing rice husks at 380–420°C under oxygen-limited conditions, with a volatile matter content ≤12%.

[0012] Preferably, the calcined kaolin powder is 1200-1500 mesh calcined kaolin with Al2O3 ≥ 38% and whiteness ≥ 80; Preferably, the red mud is Bayer process alumina red mud, which is dried and ball-milled through a 100-mesh sieve, and the heavy metal content meets the requirements of GB6566-2010.

[0013] Preferably, the silane coupling agent is at least one selected from silane coupling agent KH550, silane coupling agent KH560, and silane coupling agent KH570.

[0014] Preferably, the composite mineralizer is a mixture of limestone powder, fluorite powder, and mirabilite in a mass ratio of 3:(0.8-1.2):1.

[0015] Preferably, the viscosity of the sodium carboxymethyl cellulose is 800-1200 mPa·s; and the polyvinyl alcohol is PVA2488.

[0016] Another object of the present invention is to provide a method for preparing the environmentally friendly shale brick based on multi-source waste, comprising the following steps: Step S1, Pretreatment: Shale is crushed and ball-milled to 80-120 mesh; construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder, and red mud micro powder are ball-milled to 100-120 mesh respectively; all powders are dried at 100-110℃ until the moisture content is ≤3%; rice husk charcoal is pulverized to 40-60 mesh for later use; Step S2, Dry Mixing: Add shale, fine powder of construction waste, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin micro powder, red mud micro powder, calcium stearate and composite mineralizer to the mixer and dry mix for 5-8 minutes until uniform to obtain dry mixed powder. Step S3, Preparation of organic modified solution: Take 30-40% of the total water volume with warm water at 40-55℃, add sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate in sequence and stir until completely dissolved, then add silane coupling agent and continue stirring for 3-5 minutes to obtain a uniform organic modified aqueous solution. Step S4, wet mixing: Mix the organic modified aqueous solution with the remaining room temperature water and add it to the dry powder. Wet mix continuously for 8-12 minutes to form a plastically uniform mixture. Step S5, Aging: Place the mixture in a sealed aging chamber and age at room temperature for 24-48 hours to allow the moisture to fully diffuse and the particles to be evenly moistened. Step S6, Molding: After aging, the material is pressed into standard brick blanks under a pressure of 20-25 MPa, and the brick blanks are dried at 100-110℃ until the moisture content is ≤2%; Step S7, Segmented gradient calcination: Heat to 450-500℃ at 7-9℃ / min and hold for 28-32min to complete the pyrolysis and dehydration of organic matter; then heat to 960-1040℃ at 4-6℃ / min and hold for 60-90min to complete sintering; then slowly cool to room temperature with the furnace to obtain the finished environmentally friendly shale brick.

[0017] The beneficial effects of adopting the above technical solution are as follows: This invention achieves comprehensive performance improvement through the multi-source synergy of solid waste, mineral reinforcing components and organic modifying components: fine powder of construction waste and sludge incineration ash provide active silicon-aluminum and calcium components to generate high-strength mineral phases at high temperatures; waste ceramic powder and rice husk char respectively play the roles of rigid skeleton support and mild pore formation; combined with the low-temperature fluxing and reinforcing effects of calcined kaolin and red mud, the density and mechanical strength of the brick body are significantly improved; at the same time, CMC, PVA and sodium lignosulfonate form an organic composite modification system, which plasticizes and retains water and reduces drying cracking in the green body stage; silane coupling agent further improves the interface bonding of inorganic particles, solving the industry problem of poor compatibility of multiple solid wastes and easy generation of micro-defects. The synergistic effect of the components not only significantly reduces the drying shrinkage value and water absorption rate, making the product's dimensional stability and water resistance significantly better than conventional solid waste shale bricks, but also enables full sintering at lower temperatures, effectively reducing energy consumption and improving the finished product qualification rate. In addition, the system can achieve high-volume absorption of various solid wastes, and the product's radioactivity is far below the national standard limit. While improving the performance of wall materials, it also has outstanding environmental benefits and industrial stability. The above-mentioned overall improvement effect cannot be achieved by single or simple compound components. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solutions of the present invention and to make the above-mentioned features, objectives, and advantages of the present invention clearer and easier to understand, the present invention will be further described below with reference to embodiments. These embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Example 1

[0019] An environmentally friendly shale brick based on multi-source waste, the raw materials by weight include: 60 parts shale, 8 parts fine powder of construction waste, 5 parts sludge incineration ash, 4 parts waste ceramic powder, 2 parts rice husk charcoal, 2 parts calcined kaolin micro powder, 1 part red mud micro powder, 0.1 parts silane coupling agent, 0.2 parts calcium stearate, 1 part composite mineralizer, 0.1 parts sodium carboxymethyl cellulose, 0.05 parts polyvinyl alcohol, 0.1 parts sodium lignosulfonate, and 12 parts water.

[0020] The construction waste fine powder is a mixture of waste concrete and waste mortar, with a particle size ≤0.15mm; the sludge incineration ash is the ash residue from dewatered sludge from municipal sewage treatment plants after incineration at 600℃, with a total SiO2+Al2O3 content ≥65%; the waste ceramic powder is a grinding powder of waste daily-use ceramics and building ceramics, with a Mohs hardness ≥6.5; the rice husk charcoal is obtained by carbonizing rice husks at 380℃ under limited oxygen conditions, with volatile matter ≤12%; the calcined kaolin powder is 1200-mesh calcined kaolin, with Al2O3 ≥38% and whiteness ≥80; the red mud is Bayer process alumina red mud, dried and ball-milled to 100-mesh, with heavy metal content meeting GB standards. 6566-2010; the silane coupling agent is silane coupling agent KH550; the composite mineralizer is limestone powder, fluorite powder, and mirabilite compounded in a mass ratio of 3:0.8:1; the viscosity of the sodium carboxymethyl cellulose is 800 mPa·s; the polyvinyl alcohol is PVA2488.

[0021] A method for preparing environmentally friendly shale bricks based on multi-source waste includes the following steps: Step S1, Pretreatment: Shale is crushed and ball-milled to 80 mesh; construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder, and red mud micro powder are ball-milled to 100 mesh respectively; all powders are dried at 100℃ until the moisture content is ≤3%; rice husk charcoal is crushed to 40 mesh for later use. Step S2, Dry Mixing: Add shale, fine powder of construction waste, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin powder, red mud powder, calcium stearate and composite mineralizer to the mixer and dry mix for 5 minutes until uniform to obtain dry mixed powder. Step S3, Preparation of organic modified solution: Take 30% of the total water volume of 40℃ warm water, add sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate in sequence and stir until completely dissolved, then add silane coupling agent and continue stirring for 3 minutes to obtain a uniform organic modified aqueous solution. Step S4, Wet mixing: Mix the organic modified aqueous solution with the remaining room temperature water and add it to the dry powder. Wet mixing is carried out continuously for 8 minutes to form a plastically uniform mixture. Step S5, Aging: Place the mixture in a sealed aging chamber and age at room temperature for 24 hours to allow the moisture to fully diffuse and the particles to be evenly moistened. Step S6, Molding: After aging, the material is pressed into standard brick blanks under a pressure of 20MPa, and the brick blanks are dried at 100℃ until the moisture content is ≤2%; Step S7, Segmented gradient calcination: Heat to 450℃ at 7℃ / min and hold for 28min to complete the pyrolysis and dehydration of organic matter; then heat to 960℃ at 4℃ / min and hold for 60min to complete sintering; then slowly cool to room temperature with the furnace to obtain the finished environmentally friendly shale brick. Example 2

[0022] An environmentally friendly shale brick based on multi-source waste comprises the following raw materials by weight: 65 parts shale, 10 parts fine powder of construction waste, 6 parts sludge incineration ash, 5 parts waste ceramic powder, 3 parts rice husk charcoal, 2.5 parts calcined kaolin micro powder, 1.5 parts red mud micro powder, 0.15 parts silane coupling agent, 0.3 parts calcium stearate, 1.5 parts composite mineralizer, 0.15 parts sodium carboxymethyl cellulose, 0.07 parts polyvinyl alcohol, 0.13 parts sodium lignosulfonate, and 14 parts water.

[0023] The construction waste fine powder is a mixture of waste concrete and waste mortar, with a particle size ≤0.15mm; the sludge incineration ash is the ash residue from dewatered sludge from municipal sewage treatment plants after incineration at 630℃, with a total SiO2+Al2O3 content ≥65%; the waste ceramic powder is a grinding powder of waste daily-use ceramics and building ceramics, with a Mohs hardness ≥6.5; the rice husk charcoal is obtained by carbonizing rice husks at 390℃ under limited oxygen conditions, with a volatile matter content ≤12%; the calcined kaolin powder is 1300-mesh calcined kaolin, with Al2O3 ≥38% and whiteness ≥80; the red mud is Bayer process alumina red mud, dried and ball-milled to 100-mesh, with heavy metal content meeting GB standards. 6566-2010; the silane coupling agent is silane coupling agent KH560; the composite mineralizer is limestone powder, fluorite powder, and mirabilite compounded in a mass ratio of 3:0.9:1; the viscosity of the sodium carboxymethyl cellulose is 900 mPa·s; the polyvinyl alcohol is PVA2488.

[0024] A method for preparing environmentally friendly shale bricks based on multi-source waste includes the following steps: Step S1, Pretreatment: Shale is crushed and ball-milled to 90 mesh; construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder, and red mud micro powder are ball-milled to 105 mesh respectively; all powders are dried at 103℃ until the moisture content is ≤3%; rice husk charcoal is pulverized to 45 mesh for later use. Step S2, Dry Mixing: Add shale, fine powder of construction waste, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin micro powder, red mud micro powder, calcium stearate and composite mineralizer to the mixer and dry mix for 6 minutes until uniform to obtain dry mixed powder. Step S3, Preparation of organic modified solution: Take 33% of the total water volume of 45℃ warm water, add sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate in sequence and stir until completely dissolved, then add silane coupling agent and continue stirring for 3.5 min to obtain a uniform organic modified aqueous solution. Step S4, Wet mixing: Mix the organic modified aqueous solution with the remaining room temperature water and add it to the dry powder. Wet mixing is carried out continuously for 9 minutes to form a plastically uniform mixture. Step S5, Aging: Place the mixture in a sealed aging chamber and age at room temperature for 30 hours to allow the moisture to fully diffuse and the particles to be evenly moistened. Step S6, Molding: After aging, the material is pressed into standard brick blanks under a pressure of 22MPa, and the brick blanks are dried at 103℃ until the moisture content is ≤2%; Step S7, Segmented gradient calcination: Heat to 470℃ at 7.5℃ / min and hold for 29min to complete the pyrolysis and dehydration of organic matter; then heat to 980℃ at 4.5℃ / min and hold for 70min to complete sintering; then slowly cool to room temperature with the furnace to obtain the finished environmentally friendly shale brick. Example 3

[0025] An environmentally friendly shale brick based on multi-source waste, the raw materials by weight include: 68 parts shale, 12 parts fine powder of construction waste, 7 parts sludge incineration ash, 6 parts waste ceramic powder, 3.5 parts rice husk charcoal, 3 parts calcined kaolin micro powder, 2 parts red mud micro powder, 0.2 parts silane coupling agent, 0.35 parts calcium stearate, 2 parts composite mineralizer, 0.2 parts sodium carboxymethyl cellulose, 0.1 parts polyvinyl alcohol, 0.15 parts sodium lignosulfonate, and 15 parts water.

[0026] The construction waste fine powder is a mixture of waste concrete and waste mortar, with a particle size ≤0.15mm; the sludge incineration ash is the ash residue from dewatered sludge from municipal sewage treatment plants after incineration at 650℃, with a total SiO2+Al2O3 content ≥65%; the waste ceramic powder is a grinding powder of waste daily-use ceramics and building ceramics, with a Mohs hardness ≥6.5; the rice husk charcoal is obtained by carbonizing rice husks at 400℃ under limited oxygen conditions, with a volatile matter content ≤12%; the calcined kaolin powder is 1350-mesh calcined kaolin, with Al2O3 ≥38% and whiteness ≥80; the red mud is Bayer process alumina red mud, dried and ball-milled to 100 mesh, with heavy metal content meeting GB standards. 6566-2010; the silane coupling agent is silane coupling agent KH570; the composite mineralizer is limestone powder, fluorite powder, and mirabilite compounded in a mass ratio of 3:1:1; the viscosity of the sodium carboxymethyl cellulose is 1000 mPa·s; the polyvinyl alcohol is PVA2488.

[0027] A method for preparing environmentally friendly shale bricks based on multi-source waste includes the following steps: Step S1, Pretreatment: Shale is crushed and ball-milled to 100 mesh. Construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder, and red mud micro powder are ball-milled to 110 mesh respectively. All powders are dried at 105℃ until the moisture content is ≤3%. Rice husk charcoal is crushed to 50 mesh for later use. Step S2, Dry Mixing: Add shale, fine powder of construction waste, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin micro powder, red mud micro powder, calcium stearate and composite mineralizer to the mixer and dry mix for 5-8 minutes until uniform to obtain dry mixed powder. Step S3, Preparation of organic modified solution: Take 35% of the total water volume of 48℃ warm water, add sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate in sequence and stir until completely dissolved, then add silane coupling agent and continue stirring for 4 minutes to obtain a uniform organic modified aqueous solution. Step S4, Wet mixing: Mix the organic modified aqueous solution with the remaining room temperature water and add it to the dry powder. Wet mixing is carried out continuously for 10 minutes to form a plastically uniform mixture. Step S5, Aging: Place the mixture in a sealed aging chamber and age at room temperature for 38 hours to allow the moisture to fully diffuse and the particles to be evenly moistened. Step S6, Molding: After aging, the material is pressed into standard brick blanks under a pressure of 23MPa, and the brick blanks are dried at 105℃ until the moisture content is ≤2%; Step S7, Segmented gradient calcination: Heat to 480℃ at 8℃ / min and hold for 30min to complete the pyrolysis and dehydration of organic matter; then heat to 1020℃ at 5℃ / min and hold for 75min to complete sintering; then slowly cool to room temperature with the furnace to obtain the finished environmentally friendly shale brick. Example 4

[0028] An environmentally friendly shale brick based on multi-source waste comprises the following raw materials by weight: 73 parts shale, 13 parts fine powder of construction waste, 9 parts sludge incineration ash, 7 parts waste ceramic powder, 4.5 parts rice husk charcoal, 3.5 parts calcined kaolin micro powder, 2.5 parts red mud micro powder, 0.25 parts silane coupling agent, 0.45 parts calcium stearate, 2.5 parts composite mineralizer, 0.25 parts sodium carboxymethyl cellulose, 0.13 parts polyvinyl alcohol, 0.18 parts sodium lignosulfonate, and 17 parts water.

[0029] The construction waste fine powder is a mixture of waste concrete and waste mortar, with a particle size ≤0.15mm; the sludge incineration ash is the ash residue from dewatered sludge from municipal sewage treatment plants after incineration at 690℃, with a total SiO2+Al2O3 content ≥65%; the waste ceramic powder is a grinding powder of waste daily-use ceramics and building ceramics, with a Mohs hardness ≥6.5; the rice husk charcoal is obtained by carbonizing rice husks at 410℃ under limited oxygen conditions, with a volatile matter content ≤12%; the calcined kaolin powder is 1450-mesh calcined kaolin, with Al2O3 ≥38% and whiteness ≥80; the red mud is Bayer process alumina red mud, dried and ball-milled to 100 mesh, with heavy metal content meeting GB standards. 6566-2010; the silane coupling agent is a compound of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570 in a mass ratio of 1:2:1; the composite mineralizer is a compound of limestone powder, fluorite powder and mirabilite in a mass ratio of 3:1.1:1; the viscosity of the sodium carboxymethyl cellulose is 1100 mPa·s; the polyvinyl alcohol is PVA2488.

[0030] A method for preparing environmentally friendly shale bricks based on multi-source waste includes the following steps: Step S1, Pretreatment: Shale is crushed and ball-milled to 110 mesh. Construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder, and red mud micro powder are ball-milled to 115 mesh respectively. All powders are dried at 108℃ until the moisture content is ≤3%. Rice husk charcoal is crushed to 55 mesh for later use. Step S2, Dry Mixing: Add shale, fine powder of construction waste, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin micro powder, red mud micro powder, calcium stearate and composite mineralizer to the mixer and dry mix for 7.5 minutes until uniform to obtain dry mixed powder. Step S3, Preparation of organic modified solution: Take 38% of the total water volume of 53℃ warm water, add sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate in sequence and stir until completely dissolved, then add silane coupling agent and continue stirring for 4.5 min to obtain a uniform organic modified aqueous solution. Step S4, Wet mixing: Mix the organic modified aqueous solution with the remaining room temperature water and add it to the dry powder. Wet mixing is carried out continuously for 11 minutes to form a plastically uniform mixture. Step S5, Aging: Place the mixture in a sealed aging chamber and age at room temperature for 45 hours to allow the moisture to fully diffuse and the particles to be evenly moistened. Step S6, Molding: After aging, the material is pressed into standard brick blanks under a pressure of 24MPa, and the brick blanks are dried at 108℃ until the moisture content is ≤2%; Step S7, Segmented gradient calcination: Heat to 490℃ at 8.5℃ / min and hold for 31min to complete the pyrolysis and dehydration of organic matter; then heat to 1030℃ at 5.5℃ / min and hold for 85min to complete sintering; then slowly cool to room temperature with the furnace to obtain the finished environmentally friendly shale brick. Example 5

[0031] An environmentally friendly shale brick based on multi-source waste comprises the following raw materials by weight: 75 parts shale, 15 parts fine powder of construction waste, 10 parts sludge incineration ash, 8 parts waste ceramic powder, 5 parts rice husk charcoal, 4 parts calcined kaolin micro powder, 3 parts red mud micro powder, 0.3 parts silane coupling agent, 0.5 parts calcium stearate, 3 parts composite mineralizer, 0.3 parts sodium carboxymethyl cellulose, 0.15 parts polyvinyl alcohol, 0.2 parts sodium lignosulfonate, and 18 parts water.

[0032] The construction waste fine powder is a mixture of waste concrete and waste mortar, with a particle size ≤0.15mm; the sludge incineration ash is the ash residue from dewatered sludge from municipal sewage treatment plants after incineration at 700℃, with a total SiO2+Al2O3 content ≥65%; the waste ceramic powder is a grinding powder of waste daily-use ceramics and building ceramics, with a Mohs hardness ≥6.5; the rice husk charcoal is obtained by carbonizing rice husks at 420℃ under limited oxygen conditions, with a volatile matter content ≤12%; the calcined kaolin powder is 1500-mesh calcined kaolin, with Al2O3 ≥38% and whiteness ≥80; the red mud is Bayer process alumina red mud, dried and ball-milled to 100 mesh, with heavy metal content meeting GB standards. 6566-2010; the silane coupling agent is silane coupling agent KH550; the composite mineralizer is limestone powder, fluorite powder, and mirabilite compounded in a mass ratio of 3:1.2:1; the viscosity of the sodium carboxymethyl cellulose is 1200 mPa·s; the polyvinyl alcohol is PVA2488.

[0033] A method for preparing environmentally friendly shale bricks based on multi-source waste includes the following steps: Step S1, Pretreatment: Shale is crushed and ball-milled to 120 mesh. Construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder, and red mud micro powder are ball-milled to 120 mesh respectively. All powders are dried at 110℃ until the moisture content is ≤3%. Rice husk charcoal is crushed to 60 mesh for later use. Step S2, Dry Mixing: Add shale, fine powder of construction waste, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin powder, red mud powder, calcium stearate and composite mineralizer to the mixer and dry mix for 8 minutes until uniform to obtain dry mixed powder. Step S3, Preparation of organic modified solution: Take 40% of the total water volume of 55℃ warm water, add sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate in sequence and stir until completely dissolved, then add silane coupling agent and continue stirring for 5 minutes to obtain a uniform organic modified aqueous solution. Step S4, Wet mixing: Mix the organic modified aqueous solution with the remaining room temperature water and add it to the dry powder. Wet mixing is carried out continuously for 12 minutes to form a plastically uniform mixture. Step S5, Aging: Place the mixture in a sealed aging chamber and age at room temperature for 48 hours to allow the moisture to fully diffuse and the particles to be evenly moistened. Step S6, Molding: After aging, the material is pressed into standard brick blanks under a pressure of 25MPa, and the brick blanks are dried at 110℃ until the moisture content is ≤2%; Step S7, Segmented Gradient Firing: Heat to 500℃ at 9℃ / min and hold for 32min to complete the pyrolysis and dehydration of organic matter; then heat to 1040℃ at 6℃ / min and hold for 90min to complete sintering; then slowly cool to room temperature with the furnace to obtain the finished environmentally friendly shale brick.

[0034] Comparative Example 1 An environmentally friendly shale brick based on multi-source waste and its preparation method are basically the same as those in Example 5, except that sodium carboxymethyl cellulose is not added.

[0035] Comparative Example 2 An environmentally friendly shale brick based on multi-source waste and its preparation method are basically the same as those in Example 5, except that an equal amount of rice husk charcoal is used instead of red mud powder.

[0036] Comparative Example 3 An environmentally friendly shale brick based on multi-source waste and its preparation method are basically the same as those in Example 5, except that an equal amount of red mud powder is used instead of rice husk charcoal.

[0037] Comparative Example 4 An environmentally friendly shale brick based on multi-source waste and its preparation method are basically the same as those in Example 5, except that an equal amount of polyvinyl alcohol is used instead of sodium lignosulfonate.

[0038] Comparative Example 5 An environmentally friendly shale brick based on multi-source waste and its preparation method are basically the same as those in Example 5, except that an equal amount of sodium lignosulfonate is used instead of polyvinyl alcohol.

[0039] The following experimental methods were used to test the relevant performance of each example of environmentally friendly shale brick. The test results are shown in Table 1: (1) Compressive strength: Refer to GB / T 5101-2017, the loading rate of the pressure testing machine is 1.0kN / s, and the average value is taken.

[0040] (2) Water absorption rate: Referring to GB / T 2542-2012, five whole bricks were taken for each example, surface debris was removed, and they were dried at 105℃ to constant weight (the difference between two weighings ≤0.1%), and the dry weight was recorded as m0; they were soaked in clean water at room temperature for 24 hours, and the surface water was wiped off with a damp cloth and the wet weight was immediately weighed as m1; the water absorption rate W was calculated, W=(m1-m0) / m0×100%, and the result was taken as the average value of the five bricks, accurate to 0.1%.

[0041] (3) Limits on radionuclides: Refer to GB 6566-2010, and detect the internal exposure index I. a External radiation index Iᵧ.

[0042] (4) Firing qualification rate: Statistically calculate the proportion of bricks with no cracks, missing edges or corners, and qualified dimensions.

[0043] As shown in Table 1, the environmentally friendly shale brick prepared in Example 5 based on multi-source waste exhibits the best overall performance, with a compressive strength of 35.4 MPa, a water absorption rate of 7.2%, and an internal radiation index of I. a With a compressive strength of 0.21, an external radiation index Iᵧ of 0.31, and a finished product qualification rate of 98.2%, compared to Comparative Example 1 (without sodium carboxymethyl cellulose), Comparative Examples 2 and 3 (with red mud powder and rice husk charcoal replaced), and Comparative Examples 4 and 5 (with polyvinyl alcohol and sodium lignosulfonate replaced), Example 5 showed significantly improved compressive strength, significantly reduced water absorption, and a higher finished product qualification rate. Furthermore, the radionuclide limits of all samples met the relevant standard requirements, indicating that the formulation and preparation method of this invention can effectively improve the comprehensive performance of environmentally friendly shale bricks.

[0044] Table 1 Performance test results of environmentally friendly shale bricks based on multi-source waste project Example 5 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Compressive strength (MPa) 35.4 28.7 31.2 30.8 32.5 32.1 Water absorption rate (%) 7.2 12.5 9.8 10.2 8.5 8.8 <![CDATA[Internal exposure index I a > 0.21 0.22 0.23 0.30 0.21 0.21 External radiation index Iᵧ 0.31 0.32 0.33 0.40 0.31 0.31 Finished product pass rate (%) 98.2 88.6 94.5 93.8 96.3 95.9 The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An eco-friendly shale brick based on multi-source waste, characterized in that, The raw materials include shale 60-75 parts by weight, construction waste fine powder 8-15 parts by weight, sludge incineration ash 5-10 parts by weight, waste ceramic powder 4-8 parts by weight, rice husk charcoal 2-5 parts by weight, calcined kaolin micro powder 2-4 parts by weight, red mud micro powder 1-3 parts by weight, silane coupling agent 0.1-0.3 parts by weight, calcium stearate 0.2-0.5 parts by weight, composite mineralizer 1-3 parts by weight, sodium carboxymethyl cellulose 0.1-0.3 parts by weight, polyvinyl alcohol 0.05-0.15 parts by weight, sodium lignosulfonate 0.1-0.2 parts by weight, and water 12-18 parts by weight.

2. The eco-friendly shale brick based on multi-source waste according to claim 1, characterized in that, The construction waste fine powder is a mixture of waste concrete and waste mortar fine powder, and the particle size is ≤0.15 mm.

3. The eco-friendly shale brick based on multi-source waste according to claim 1, characterized in that, The sludge incineration ash is ash residue of dewatered sludge from a municipal sewage treatment plant after incineration at 600-700 ℃, and the total content of SiO2+Al2O3 is ≥65%; the waste ceramic powder is waste domestic ceramic and building ceramic grinding powder, and the Mohs hardness is ≥6.

5.

4. The eco-friendly shale brick based on multi-source waste according to claim 1, wherein, The rice husk charcoal is obtained by carbonization of rice husk at 380-420 ℃ under limited oxygen conditions, and the volatile matter content is ≤12%; the calcined kaolin micro powder is 1200-1500 mesh calcined kaolin, and the Al2O3 content is ≥38% and the whiteness is ≥80.

5. The eco-friendly shale brick based on multi-source waste according to claim 1, wherein, The red mud is Bayer process alumina red mud, which is dried and ball milled to 100 mesh, and the heavy metal content meets GB 6566-2010.

6. The eco-friendly shale brick based on multi-source waste according to claim 1, wherein, The silane coupling agent is at least one of silane coupling agent KH550, silane coupling agent KH560 and silane coupling agent KH570.

7. The eco-friendly shale brick based on multi-source waste according to claim 1, wherein, The composite mineralizer is a compound of limestone powder, fluorite powder and mirabilite at a mass ratio of 3:(0.8-1.2):

1.

8. The eco-friendly shale brick based on multi-source waste according to claim 1, wherein, The viscosity of the sodium carboxymethyl cellulose is 800-1200 mPa·s, and the polyvinyl alcohol is PVA2488.

9. A method of manufacturing an environmentally friendly shale brick based on multi-source waste according to any one of claims 1-8, characterized in that, The method comprises the following steps: Step S1, pretreatment: the shale is crushed and ball milled to 80-120 mesh, the construction waste fine powder, sludge incineration ash, waste ceramic powder, calcined kaolin micro powder and red mud micro powder are respectively ball milled to 100-120 mesh, and all the powders are dried at 100-110 ℃ to a water content of ≤3%; the rice husk charcoal is crushed to 40-60 mesh for use; Step S2, dry mixing: the shale, construction waste fine powder, sludge incineration ash, waste ceramic powder, rice husk charcoal, calcined kaolin micro powder, red mud micro powder, calcium stearate and composite mineralizer are added into a mixer, dry mixed for 5-8 min to be uniform, and dry mixed powder is obtained; Step S3, preparation of organic modification liquid: warm water at 40-55 ℃ is taken at 30-40% of the total water amount, and the sodium carboxymethyl cellulose, polyvinyl alcohol and sodium lignosulfonate are added in sequence and stirred until completely dissolved, then the silane coupling agent is added and stirred for 3-5 min, and a uniform organic modification aqueous solution is prepared; Step S4, wet mixing: the organic modification aqueous solution and the remaining normal temperature water are mixed and then added into the dry mixed powder, and continuous wet mixing is performed for 8-12 min to form a plastic and uniform mixture; Step S5, aging: the mixture is placed in a sealed aging tank for aging at normal temperature for 24-48 h to fully diffuse the water and uniformly wet the particles. Step S6, molding: the material after aging is pressed into standard brick billets under a pressure of 20-25 MPa, and the brick billets are dried at 100-110 ℃ until the water content is ≤2%; Step S7, sectional gradient baking: the temperature is raised to 450-500 ℃ at a rate of 7-9 ℃ / min and kept for 28-32 min to complete the pyrolysis and dehydration of the organic matter; then the temperature is raised to 960-1040 ℃ at a rate of 4-6 ℃ / min, and kept for 60-90 min to complete sintering; and then slow cooling is performed with the furnace to room temperature to obtain finished product environment-friendly shale brick.