Method for preparing baking-free bricks by tailings in machine-made sand production process

Abstract

This application discloses a method for preparing non-fired bricks from tailings during the production of manufactured sand, belonging to the technical field of building energy-saving and thermal insulation materials. The method includes the following steps: S1, pretreatment of manufactured sand tailings; S2, stirring treatment; S3, low-temperature vacuum drying treatment; S4, raw material preparation; S5, stirring and mixing; S6, brick forming; and S7, curing. The non-fired bricks prepared by this method have high density. The various operation steps have a certain synergistic effect, and their mutual cooperation can significantly improve the compressive strength and flexural strength of the non-fired bricks, greatly enhancing their mechanical properties. Furthermore, the water absorption rate of the non-fired bricks prepared by this method does not change significantly within 1–7 days of soaking in water, and its water absorption rate at different soaking times meets the requirement of less than 20% after 24 hours of soaking as specified in the "Industry Standard for Non-Sintered Ordinary Clay Bricks". The non-fired bricks prepared by this method improve mechanical strength while ensuring water resistance, exhibiting relatively low water absorption and excellent durability.

Description

Technical Field

[0001] This invention belongs to the technical field of building energy-saving thermal insulation materials, specifically relating to a method for preparing non-fired bricks from tailings during the production of manufactured sand. Background Technology

[0002] In recent years, with the expansion of market demand and the rapid increase in sand consumption, the mining of natural sand has been restricted, making the use of manufactured sand in the construction industry imperative and already widely promoted and used. Currently, the production rate of manufactured sand production equipment is 15-35%, generating a large amount of tailings during the production process. The main methods for treating manufactured sand tailings are roadbed backfilling and cement mixing, which can consume about 50% of the tailings. Landfilling remains the primary disposal method, but this seriously affects the ecological restoration of arable land and forest land. The environmental pollution and resource waste caused by manufactured sand tailings remain a very serious problem.

[0003] Non-fired bricks are a new type of wall material made from fly ash, coal slag, coal gangue, tailings slag, chemical slag, or natural sand and marine mud as main raw materials, without high-temperature firing. Because of its high strength, durability, standard dimensions, complete shape, uniform color, and rustic natural appearance, this material can be used for exposed brick walls or any exterior decoration.

[0004] Non-fired bricks are a new type of material. Therefore, applying manufactured sand tailings to non-fired brick production can not only alleviate the shortage of raw materials for non-fired bricks but also fully utilize manufactured sand tailings, simultaneously solving the problems of two industries. It can also reduce the emission of harmful gases. Currently, in terms of wall building materials, new wall materials account for a large proportion (around 90%) in Europe and America; in Japan, the proportion is as high as 97%. For my country, the development of "new green building materials" will be the main theme of future development, and non-fired bricks will inevitably replace solid clay bricks, becoming the major direction of building material development.

[0005] Although there is some research on the preparation of non-fired bricks from manufactured sand tailings, the research is very limited and the technology is not yet mature enough, and the strength of the prepared non-fired bricks needs to be further improved.

[0006] Furthermore, excessive stone powder and mud in manufactured sand cannot be separated by sieving, and water washing is a common treatment method. To achieve the recycling of sand washing water, reduce production costs, and meet green environmental protection requirements, flocculants are usually used to filter the washing water. However, this also results in flocculant residue, which can seriously affect the quality of unfired bricks. Therefore, it is necessary to minimize the negative impact of flocculant presence on unfired bricks during the preparation of unfired bricks. Summary of the Invention

[0007] The purpose of this invention is to address existing problems by providing a method for preparing non-fired bricks from tailings during the production of manufactured sand.

[0008] This invention is achieved through the following technical solution:

[0009] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0010] S1. Pretreatment of manufactured sand tailings:

[0011] S101. Place the collected machine-made sand tailings in a vacuum drying oven for ultraviolet vacuum drying treatment until the moisture content is 0.8-1%.

[0012] The above technical solution allows for the sterilization of manufactured sand under ultraviolet vacuum conditions. In addition, the low-temperature drying process allows the manufactured sand to heat up slowly from the outside to the inside, generating a certain vapor pressure. This vapor pressure increases the porosity of the manufactured sand, accelerates the drying efficiency, and works synergistically with ultraviolet light to break down the flocculant residue on the manufactured sand tailings, thereby reducing the amount of flocculant residue.

[0013] S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Perform bead milling under ultrasonic action. After completion, take out the machine-made sand tailings I for later use.

[0014] By adopting the above technical solution, bead milling is carried out under the assistance of ultrasound. The rotation speed of the bead mill and the parameters of the ultrasound are strictly controlled. The cavitation effect, thermal effect and other effects of the ultrasound work together with the mechanical shearing action to further break the chemical bonds of the flocculant and form free radical fragments, thereby further reducing the residual amount of flocculant. At the same time, it increases the specific surface area of ​​the manufactured sand tailings and reduces the fineness, laying a good foundation for subsequent operations.

[0015] S2. Stirring process:

[0016] Sepiolite and the manufactured sand tailings I obtained in step S1 are placed in a mixing tank at a weight ratio of 1:10-12, and sprayed while stirring to obtain mixture I for later use.

[0017] S3. Low-temperature vacuum drying treatment:

[0018] The mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying. After the drying was completed, the mixture II was taken out for later use.

[0019] By adopting the above technical solution, sepiolite and manufactured sand tailings I are placed in a mixing chamber in a certain proportion. While mixing, a special spray is sprayed onto the surface of sepiolite and manufactured sand tailings. Due to the property that sepiolite absorbs a lot of water and becomes soft when it comes into contact with water, most of the spray is absorbed by the sepiolite when it is sprayed, and thus continues to play a role in sterilization and improving surface activity in subsequent processing.

[0020] S4. Raw material preparation:

[0021] Weigh out the corresponding weight percentages of fly ash 6-8%, coal gangue 6-8%, bentonite 10-12%, water-reducing agent 0.3-0.6%, and mixture II 10-20%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0022] S5. Stir and mix thoroughly:

[0023] After adding the raw materials prepared in step S4 into the mixer and mixing them evenly, add water at a water-to-material ratio of 1:8 to 12 and mix at varying speeds. After completion, the mixture III is ready for use.

[0024] By adopting the above technical solution, this application breaks away from conventional stirring methods. After adding water, variable-speed stirring is performed. First, low-speed stirring ensures thorough mixing while the raw materials fully absorb water, and mixture I expands to a certain extent, resulting in close contact between the materials. Then, rapid stirring is performed. On the one hand, this disrupts the structure, reducing flocculant residue; on the other hand, the rapid stirring breaks down the interfacial effects between the raw materials, promoting their fusion. Simultaneously, with the participation of water, a hydration film forms on the surface of each raw material. Under the action of the common water film generated by the superposition of various materials, some chemical bonds break, leading to ionization and weakening the interfacial effects between the interfaces. This allows the raw materials to come into contact and fuse, forming a complete system structure, thereby improving the mechanical strength of the finished product.

[0025] S6. Brick forming:

[0026] The mixture III obtained in step S5 is conveyed to the molding die of the brick making machine by a conveyor.

[0027] S7, Maintenance:

[0028] After the bricks are formed, they are steam cured to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0029] Furthermore, the drying temperature is controlled at 50–70°C during the ultraviolet vacuum drying process described in step S101.

[0030] Furthermore, the size of the tailings slag in the bead milling treatment control mechanism described in step S102 is 1–5 μm.

[0031] Further, the components and corresponding weight percentages of the spray agent used in the spray treatment in step S2 are as follows: fatty acid glycerides 6-8%, fulvic acid 3-6%, linoleic acid 7-9%, α-bisabolol 4-6%, propylene glycol 2-3%, trans-β-farnesene 0.6-0.8%, with the balance being water. The amount of the spray agent used is 2-3% of the weight of the manufactured sand tailings I.

[0032] Furthermore, the stirring speed of the stirring tank during step S2 is 200-300 rpm.

[0033] Furthermore, during the low-temperature vacuum drying process described in step S3, the temperature is controlled at 30–40°C, and the product is dried to a moisture content of 0.6–0.8%.

[0034] Furthermore, the variable-speed stirring described in step S5 specifically involves stirring at a speed of 90–120 rpm for 1–2 hours, and then continuing to stir at a speed of 1600–2000 rpm for 20–40 minutes.

[0035] Furthermore, the molding pressure described in step S6 is 3 to 4 MPa.

[0036] Furthermore, the steam curing temperature described in step S7 is 90–95°C.

[0037] The present invention has the following advantages over the prior art:

[0038] This application provides a method for preparing non-fired bricks from tailings during the production of manufactured sand. The non-fired bricks prepared by this method have high density, with average compressive strengths of 19.6 MPa, 19.7 MPa, and 19.9 MPa at 7d, 14d, and 28d, respectively, and flexural strengths of 2.1 MPa, 2.3 MPa, and 2.4 MPa, respectively. These strengths are significantly superior to those of non-fired bricks prepared by comparative methods. This indicates a synergistic effect between the various operational steps of this method, which significantly improves the compressive and flexural strengths of the non-fired bricks, thereby greatly enhancing their mechanical properties. Furthermore, the water absorption rate of the non-fired bricks prepared by this method does not change significantly within 1–7 days of immersion in water, meeting the requirement of less than 20% water absorption after 24 hours of immersion as specified in the "Industry Standard for Non-Sintered Ordinary Clay Bricks". The non-fired bricks prepared by this method improve mechanical strength while maintaining water resistance, exhibiting relatively low water absorption and excellent durability. Attached Figure Description

[0039] Figure 1 The relationship between the compressive strength of unfired bricks and the curing age;

[0040] Figure 2The relationship between the flexural strength of unfired bricks and the curing age;

[0041] Figure 3 The relationship between the water absorption rate of unfired bricks and soaking time. Detailed Implementation

[0042] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0043] Example 1

[0044] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0045] S1. Pretreatment of manufactured sand tailings:

[0046] S101. Place the collected machine-made sand tailings in a vacuum drying oven for ultraviolet vacuum drying treatment, control the drying temperature at 50℃, and dry until the moisture content is 0.8%.

[0047] S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Under ultrasonic action, perform bead milling treatment until 1μm is ground. After completion, take out the machine-made sand tailings I for later use.

[0048] S2. Stirring process:

[0049] Sepiol and the machine-made sand tailings I obtained in step S1 were placed in a mixing tank at a weight ratio of 1:10. The mixture was sprayed while being stirred at a speed of 200 rpm. The components and corresponding weight percentages of the spray agent were as follows: fatty acid glycerides 6%, fulvic acid 3%, linoleic acid 7%, α-bisabolol 4%, propylene glycol 2%, trans-β-farnesene 0.6%, and the balance being water. The amount of the spray agent used was 2% of the weight of the machine-made sand tailings I to obtain mixture I for later use.

[0050] S3. Low-temperature vacuum drying treatment:

[0051] Mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying at a controlled temperature of 30°C. After drying to a moisture content of 0.6%, mixture II was taken out for later use.

[0052] S4. Raw material preparation:

[0053] Weigh out the corresponding weight percentages of fly ash 6%, coal gangue 6%, bentonite 10%, water reducing agent 0.3%, and mixture II 10%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0054] S5. Stir and mix thoroughly:

[0055] Add the raw materials prepared in step S4 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:8. First, stir at 90 rpm for 1 hour, and then continue stirring at 1600 rpm for 20 minutes. After completion, the mixture III is ready for use.

[0056] S6. Brick forming:

[0057] The mixture III obtained in step S5 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 3MPa.

[0058] S7, Maintenance:

[0059] After the bricks are formed, they are steam cured at 90℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0060] Example 2

[0061] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0062] S1. Pretreatment of manufactured sand tailings:

[0063] S101. The collected machine-made sand tailings are placed in a vacuum drying oven for ultraviolet vacuum drying treatment. The drying temperature is controlled at 60℃ and the moisture content is dried to 0.9%.

[0064] S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Under the action of ultrasound, perform bead milling treatment until 3μm. After completion, take out the machine-made sand tailings I for later use.

[0065] S2. Stirring process:

[0066] Sepiol and the machine-made sand tailings I obtained in step S1 were placed in a mixing tank at a weight ratio of 1:11. The mixture was sprayed while being stirred at a speed of 250 rpm. The components and corresponding weight percentages of the spray agent were as follows: fatty acid glycerides 7%, fulvic acid 4.5%, linoleic acid 8%, α-bisabolol 5%, propylene glycol 2.5%, trans-β-farnesene 0.7%, and the balance being water. The amount of the spray agent used was 2.5% of the weight of the machine-made sand tailings I to obtain mixture I for later use.

[0067] S3. Low-temperature vacuum drying treatment:

[0068] Mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying at a controlled temperature of 35°C. After drying to a moisture content of 0.7%, mixture II was taken out for later use.

[0069] S4. Raw material preparation:

[0070] Weigh out the corresponding weight percentages of fly ash 7%, coal gangue 7%, bentonite 11%, water reducing agent 0.45%, and mixture II 15%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0071] S5. Stir and mix thoroughly:

[0072] Add the raw materials prepared in step S4 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:10. First, stir at 105 rpm for 1.5 hours, and then continue stirring at 1800 rpm for 30 minutes. After completion, the mixture III is ready for use.

[0073] S6. Brick forming:

[0074] The mixture III obtained in step S5 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 3.5 MPa.

[0075] S7, Maintenance:

[0076] After the bricks are formed, they are steam cured at 93℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0077] Example 3

[0078] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0079] S1. Pretreatment of manufactured sand tailings:

[0080] S101. The collected machine-made sand tailings are placed in a vacuum drying oven for ultraviolet vacuum drying treatment. The drying temperature is controlled at 70℃ and the moisture content is dried to 1%.

[0081] S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Under the action of ultrasound, perform bead milling treatment until it reaches 5μm. After completion, take it out to obtain machine-made sand tailings I for later use.

[0082] S2. Stirring process:

[0083] Sepiol and the machine-made sand tailings I obtained in step S1 were placed in a mixing tank at a weight ratio of 1:12. The mixture was sprayed while being stirred at 300 rpm. The components and corresponding weight percentages of the spray agent were as follows: fatty acid glycerides 8%, fulvic acid 6%, linoleic acid 9%, α-bisabolol 6%, propylene glycol 3%, trans-β-farnesene 0.8%, and the balance was water. The amount of the spray agent used was 3% of the weight of the machine-made sand tailings I to obtain mixture I for later use.

[0084] S3. Low-temperature vacuum drying treatment:

[0085] Mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying at a controlled temperature of 40°C. After drying to a moisture content of 0.8%, mixture II was taken out for later use.

[0086] S4. Raw material preparation:

[0087] Weigh out the corresponding weight percentages of fly ash 8%, coal gangue 8%, bentonite 12%, water reducing agent 0.6%, and mixture II 20%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0088] S5. Stir and mix thoroughly:

[0089] Add the raw materials prepared in step S4 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:12. First, stir at 120 rpm for 2 hours, and then continue stirring at 2000 rpm for 40 minutes. After completion, the mixture III is ready for use.

[0090] S6. Brick forming:

[0091] The mixture III obtained in step S5 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 4MPa.

[0092] S7, Maintenance:

[0093] After the bricks are formed, they are steam cured at 95℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0094] Comparative Example 1:

[0095] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0096] S1. Pretreatment of manufactured sand tailings:

[0097] S101. Place the collected machine-made sand tailings in a drying oven for drying treatment, control the drying temperature at 60℃, and dry until the moisture content is 0.9%.

[0098] S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Under the action of ultrasound, perform bead milling treatment until 3μm. After completion, take out the machine-made sand tailings I for later use.

[0099] S2. Stirring process:

[0100] Sepiol and the machine-made sand tailings I obtained in step S1 were placed in a mixing tank at a weight ratio of 1:11. The mixture was sprayed while being stirred at a speed of 250 rpm. The components and corresponding weight percentages of the spray agent were as follows: fatty acid glycerides 7%, fulvic acid 4.5%, linoleic acid 8%, α-bisabolol 5%, propylene glycol 2.5%, trans-β-farnesene 0.7%, and the balance being water. The amount of the spray agent used was 2.5% of the weight of the machine-made sand tailings I to obtain mixture I for later use.

[0101] S3. Low-temperature vacuum drying treatment:

[0102] Mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying at a controlled temperature of 35°C. After drying to a moisture content of 0.7%, mixture II was taken out for later use.

[0103] S4. Raw material preparation:

[0104] Weigh out the corresponding weight percentages of fly ash 7%, coal gangue 7%, bentonite 11%, water reducing agent 0.45%, and mixture II 15%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0105] S5. Stir and mix thoroughly:

[0106] Add the raw materials prepared in step S4 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:10. First, stir at 105 rpm for 1.5 hours, and then continue stirring at 1800 rpm for 30 minutes. After completion, the mixture III is ready for use.

[0107] S6. Brick forming:

[0108] The mixture III obtained in step S5 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 3.5 MPa.

[0109] S7, Maintenance:

[0110] After the bricks are formed, they are steam cured at a temperature of 93℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0111] Comparative Example 2:

[0112] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0113] S1. Pretreatment of manufactured sand tailings:

[0114] The collected machine-made sand tailings were placed in a vacuum drying oven for ultraviolet vacuum drying treatment. The drying temperature was controlled at 60℃, and the moisture content was dried to 0.9% to obtain machine-made sand tailings I for later use.

[0115] S2. Stirring process:

[0116] Sepiol and the machine-made sand tailings I obtained in step S1 were placed in a mixing tank at a weight ratio of 1:11. The mixture was sprayed while being stirred at a speed of 250 rpm. The components and corresponding weight percentages of the spray agent were as follows: fatty acid glycerides 7%, fulvic acid 4.5%, linoleic acid 8%, α-bisabolol 5%, propylene glycol 2.5%, trans-β-farnesene 0.7%, and the balance being water. The amount of the spray agent used was 2.5% of the weight of the machine-made sand tailings I to obtain mixture I for later use.

[0117] S3. Low-temperature vacuum drying treatment:

[0118] Mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying at a controlled temperature of 35°C. After drying to a moisture content of 0.7%, mixture II was taken out for later use.

[0119] S4. Raw material preparation:

[0120] Weigh out the corresponding weight percentages of fly ash 7%, coal gangue 7%, bentonite 11%, water reducing agent 0.45%, and mixture II 15%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0121] S5. Stir and mix thoroughly:

[0122] Add the raw materials prepared in step S4 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:10. First, stir at 105 rpm for 1.5 hours, and then continue stirring at 1800 rpm for 30 minutes. After completion, the mixture III is ready for use.

[0123] S6. Brick forming:

[0124] The mixture III obtained in step S5 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 3.5 MPa.

[0125] S7, Maintenance:

[0126] After the bricks are formed, they are steam cured at a temperature of 93℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0127] Comparative Example 3:

[0128] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0129] S1. Pretreatment of manufactured sand tailings:

[0130] The collected machine-made sand tailings were placed in a vacuum drying oven for ultraviolet vacuum drying treatment, with the drying temperature controlled at 60℃, until the moisture content was 0.9%.

[0131] S2. Raw material preparation:

[0132] Weigh out the corresponding weight percentages of fly ash 7%, coal gangue 7%, bentonite 11%, and water-reducing agent 0.45%, with the remainder being the dried machine-made sand tailings from step S1 for later use.

[0133] S3. Stir and mix thoroughly:

[0134] Add the raw materials prepared in step S2 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:10. First, mix at 105 rpm for 1.5 hours, and then continue mixing at 1800 rpm for 30 minutes. The resulting mixture is ready for use.

[0135] S4. Brick forming:

[0136] The mixture obtained in step S3 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 3.5 MPa.

[0137] S5, Maintenance:

[0138] After the bricks are formed, they are steam cured at a temperature of 93℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0139] Comparative Example 4:

[0140] A method for preparing non-fired bricks from tailings during manufactured sand production includes the following steps:

[0141] S1. Pretreatment of manufactured sand tailings:

[0142] S101. The collected machine-made sand tailings are placed in a vacuum drying oven for ultraviolet vacuum drying treatment. The drying temperature is controlled at 60℃ and the moisture content is dried to 0.9%.

[0143] S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Under the action of ultrasound, perform bead milling treatment until 3μm. After completion, take out the machine-made sand tailings I for later use.

[0144] S2. Stirring process:

[0145] Sepiol and the machine-made sand tailings I obtained in step S1 were placed in a mixing tank at a weight ratio of 1:11. The mixture was sprayed while being stirred at a speed of 250 rpm. The components and corresponding weight percentages of the spray agent were as follows: fatty acid glycerides 7%, fulvic acid 4.5%, linoleic acid 8%, α-bisabolol 5%, propylene glycol 2.5%, trans-β-farnesene 0.7%, and the balance being water. The amount of the spray agent used was 2.5% of the weight of the machine-made sand tailings I to obtain mixture I for later use.

[0146] S3. Low-temperature vacuum drying treatment:

[0147] Mixture I obtained in S2 was placed in a vacuum drying oven for low-temperature vacuum drying at a controlled temperature of 35°C. After drying to a moisture content of 0.7%, mixture II was taken out for later use.

[0148] S4. Raw material preparation:

[0149] Weigh out the corresponding weight percentages of fly ash 7%, coal gangue 7%, bentonite 11%, water reducing agent 0.45%, and mixture II 15%, with the remainder being the dried machine-made sand tailings from step S101 for later use.

[0150] S5. Stir and mix thoroughly:

[0151] Add the raw materials prepared in step S4 into the mixer in sequence and mix well. Then add water at a water-to-material ratio of 1:10 and mix well to obtain mixture III for later use.

[0152] S6. Brick forming:

[0153] The mixture III obtained in step S5 is conveyed by a conveyor to the molding die of the brick making machine and pressed into shape at 3.5 MPa.

[0154] S7, Maintenance:

[0155] After the bricks are formed, they are steam cured at a temperature of 93℃ to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

[0156] test

[0157] 1. Density

[0158] Using the non-fired bricks prepared by the methods in Examples 1 to 3 as the test objects, five non-fired brick samples were taken from each group for density testing, and the average density of the five samples was taken as the final result.

[0159] Table 1

[0160] <![CDATA[Density (kg / m 3 )]]> Example 1 1743.09 Example 2 1753.32 Example 3 1749.52

[0161] As can be seen from Table 1, the non-fired bricks prepared by the method of this application have a high density.

[0162] 2. Compressive strength

[0163] Using the unfired bricks prepared by the methods of Examples 2 and Comparative Examples 1-4 as test objects, five unfired bricks were taken from each group as specimens. The length and width of the pressure surface of each specimen were measured. The specimen was placed in the center of the pressure plate of the press, and the load was applied at a uniform and stable speed of 2-6 kN / s until the specimen failed. The maximum failure load P was recorded. Impact or vibration was avoided during the process. The compressive strength Rp of the specimen was calculated according to the following formula.

[0164]

[0165] Where: Rp—compressive strength, MPa; P—maximum failure load, N; L—length of the pressure surface (connection surface), mm; B—width of the pressure surface (connection surface), mm.

[0166] The results are as follows Figure 1 As shown.

[0167] 3. Flexural strength

[0168] Using the unfired bricks prepared by the methods of Examples 2 and Comparative Examples 1-4 as test objects, five unfired bricks were taken from each group as specimens. The width B and thickness H of the middle of each specimen were measured. Then, the universal testing machine used for testing and the distance L between the supports for placing the brick specimens were adjusted. The specimens were placed parallel to each other at the midpoint of the support spacing and pressure was applied uniformly and steadily at a speed of 50-150 N / s until the brick specimen broke. The maximum breaking load P applied during this process was recorded. The flexural strength Rc of the unfired bricks was calculated according to the following formula.

[0169]

[0170] Where: Rc—flexural strength, MPa; P—maximum failure load, N; L—span of specimen, equal to 50 mm; B—width of specimen, mm; H—height of specimen, mm.

[0171] The results are as follows Figure 2 As shown.

[0172] Depend on Figure 1 and Figure 2It can be seen that the average compressive strength of the unfired bricks prepared by the method of this application at 7d, 14d and 28d are 19.6MPa, 19.7MPa and 19.9MPa, respectively, and the flexural strength is 2.1MPa, 2.3MPa and 2.4MPa, respectively. The strength is significantly better than that of the unfired bricks prepared by the methods of comparative examples 1 to 4. That is, there is a certain synergistic effect between the various operation steps of the method of this application. The cooperation between them can significantly improve the compressive strength and flexural strength of the unfired bricks and greatly improve the mechanical properties of the unfired bricks.

[0173] 4. Water absorption

[0174] Using the non-fired bricks prepared by the methods of Example 2 and Comparative Examples 1-4 as test objects, five non-fired bricks from each group were taken as test pieces and placed in an oven to dry to constant weight. After removing the surface dust, the mass after drying was weighed, and then the bricks were soaked in room temperature water for a set time. After the test, the test pieces were taken out, excess water on the surface was removed, and the bricks were weighed.

[0175] The water absorption rate W24 of the sample soaked at room temperature for 24 hours is calculated according to the following formula.

[0176]

[0177] Where: W24—water absorption rate of the sample after soaking in water at room temperature for 24 hours, %; G0—mass of the sample in dry state, g; G24—mass of the sample after soaking in water for 24 hours, g.

[0178] The results are as follows Figure 3 As shown.

[0179] Depend on Figure 3 It can be seen that the water absorption rate of the unfired bricks prepared by the method of this application does not change much within 1 to 7 days of soaking in water, and its water absorption rate at different soaking times meets the requirement of less than 20% for 24 hours of soaking in the "Industry Standard for Non-Sintered Ordinary Clay Bricks". Compared with comparative examples 1 to 4, it can be concluded that the unfired bricks prepared by the method of this application improve mechanical strength while ensuring waterproofness, with relatively low water absorption and excellent durability.

[0180] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a non-fired brick from tailings in a manufactured sand production process, characterized by, Includes the following steps: S1. Pretreatment of manufactured sand tailings: S101. Place the collected machine-made sand tailings in a vacuum drying oven for ultraviolet vacuum drying treatment until the moisture content is 0.8~1%; S102. Take a portion of the dried machine-made sand tailings and place it in a bead mill. Perform bead milling under ultrasonic action. After completion, take out the machine-made sand tailings I for later use. S2. Stirring process: Sepiolite and the manufactured sand tailings I obtained in step S1 are placed in a mixing tank at a weight ratio of 1:10~12, and sprayed while stirring to obtain mixture I for later use. The components and corresponding weight percentages of the spray agent used in the spray treatment are as follows: fatty acid glycerides 6-8%, fulvic acid 3-6%, linoleic acid 7-9%, α-bisabolol 4-6%, propylene glycol 2-3%, trans-β-farnesene 0.6-0.8%, with the balance being water. The amount of the spray agent used is 2-3% of the weight of the manufactured sand tailings I. S3. Low-temperature vacuum drying treatment: The mixture I obtained in S2 is placed in a vacuum drying oven for low-temperature vacuum drying. After completion, the mixture II is taken out for later use. The temperature is controlled at 30~40℃ during the low-temperature vacuum drying process. S4. Raw material preparation: Weigh out the corresponding weight percentages of fly ash 6-8%, coal gangue 6-8%, bentonite 10-12%, water-reducing agent 0.3-0.6%, and mixture II 10-20%, with the remainder being the dried machine-made sand tailings from step S101 for later use. S5. Stir and mix thoroughly: After adding the raw materials prepared in step S4 into the mixer and mixing them evenly, add water at a water-to-material ratio of 1:8~12 and mix at varying speeds. After completion, the mixture III is ready for use. S6. Brick forming: The mixture III obtained in step S5 is conveyed to the molding die of the brick making machine by a conveyor. S7, Maintenance: After the bricks are formed, they are steam cured to increase their strength to 70% of the design strength. Then they are placed in the finished product storage area and air-dried naturally to obtain the finished product.

2. A method for preparing fired bricks from tailings in a process for producing machine-made sand according to claim 1, characterized in that, In step S101, the ultraviolet vacuum drying process is performed at a temperature of 50-70°C.

3. A method of manufacturing baking-free bricks from tailings in a process of producing manufactured sand according to claim 1, characterized in that, The particle size of the sand tailings from the bead milling process described in step S102 is 1~5μm.

4. The method as claimed in claim 1, wherein the tailings of the process of producing the manufactured sand are used for the production of the non-burnt bricks. The stirring speed of the stirring tank during step S2 is 200~300 rpm.

5. The method as claimed in claim 1, wherein the tailings of the process of producing the manufactured sand are used for the production of the non-burnt bricks. The low-temperature vacuum drying process described in step S3 is used to dry the material to a moisture content of 0.6-0.8%.

6. A method of manufacturing baking-free bricks from tailings in a process of producing manufactured sand according to claim 1, characterized in that, The variable speed stirring in step S5 is specifically as follows: first stir at a speed of 90~120 rpm for 1~2 hours, and then continue stirring at a speed of 1600~2000 rpm for 20~40 minutes.

7. The method as claimed in claim 1, wherein the tailings are prepared into the baking-free bricks in the process of producing the machine-made sand. The molding pressure described in step S6 is 3~4 MPa.

8. The method of producing fired bricks using tailings from a process of producing manufactured sand according to claim 1, characterized in that, The temperature for steam curing in step S7 is 90~95℃.

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