Composite foamed ceramsite as well as preparation method and application thereof

Abstract

The invention provides composite foamed ceramsite as well as a preparation method and application thereof. Industrial waste machine-made sand waste mud and / or anode mud are / is used as main raw materials, a foaming agent is added, the lightweight aggregate is prepared through a process, and the machine-made sand waste mud and / or anode mud are / is byproducts in the industrial production process and need to be treated and disposed with cost. And the waste is converted into the ceramsite, so that the waste treatment cost can be reduced, the environmental treatment cost can be reduced, the dependence on natural gravel resources can be reduced, and the cost is saved. The machine-made sand waste mud / anode mud is converted into useful ceramsite, accumulation and landfill of waste are reduced, pollution of the waste to the environment can be reduced, and sustainable development is facilitated. The resource utilization of the machine-made sand waste mud / anode mud can reduce the exploitation of natural resources, and is beneficial to the protection of the ecological environment.

Description

Technical Field

[0001] The present invention relates to the technical field of solid waste utilization and expanded ceramsite preparation, and particularly relates to a composite expanded ceramsite, a preparation method thereof, and an application thereof. Background Art

[0002] Construction sand and gravel is an important raw material for constructing the concrete skeleton. With the tightening of natural sand and gravel resources constraints and the increasing enhancement of environmental protection, quarrying has been prohibited in many places, resulting in a continuous increase in the price of gravel. Therefore, manufactured sand has gradually become the main source of construction sand and gravel in China. However, in the production process of manufactured sand, due to process steps such as crushing, screening, and sand making, a large amount of waste stone chips and waste mud will be generated. Currently, the productivity of sand making equipment is between 15% and 35%, and the country will generate no less than 4 billion tons of tail mud every year.

[0003] It is difficult to use this waste mud for planting purposes. Therefore, the process needs to be improved to turn the sludge into a valuable resource. Currently, the main treatment methods for waste mud in China include land use, sanitary landfill, incineration, building material utilization, etc., and there is still room for improvement in treatment technology and experience. Currently, relatively mature treatment technologies include subgrade backfilling and cement blending. These methods can treat about 50% of the tail mud, and the remaining tail mud can only be stored in the form of yard stacking. This method not only occupies a large amount of land, causing a waste of land resources, but also will cause certain pollution to groundwater and soil, imposing a burden on the ecological environment. Therefore, its comprehensive and efficient utilization has become an urgent problem to be solved, which will directly relate to the sustainable development of China's future industry and ecological environmental protection issues.

[0004] Ceramsite is a granular material. Due to its light weight, the shape of ceramsite is mostly spherical or ellipsoidal, and some are irregular gravels, rather than circular or elliptical spheres. The surface layer is a hard shell of porcelain or pottery, which can not only prevent water from entering, but also keep the internal gas from escaping, and at the same time enable the ceramsite to have a certain strength. Among them, expanded ceramsite is a multifunctional material with many advantages and can be used in many aspects such as construction, horticulture, and environmental protection.

[0005] Traditionally, the manufacture of ceramsite mainly relies on non-sustainable resources such as clay and shale. Facing the problem of resource shortage and the increasing awareness of environmental protection, the raw material selection for ceramsite production is gradually changing, and more and more industrial by-products and solid waste are being used. For example, industrial waste materials such as fly ash and slag after appropriate treatment can be converted into alternative raw materials for ceramsite production. This approach not only reduces the dependence on limited natural resources, but also promotes the recycling of resources and helps to reduce environmental pollution.

[0006] The invention patent with the publication number CN111018559A provides a lightweight and high-strength ceramsite and a preparation method thereof. The ceramsite is spherical, with a diameter of 3 - 20 mm, a strength ≥ 1.5, a mass of 350 kg ± 30 kg / m3, and λ < 0.10 w / m.k. More than 95% of the raw materials for producing the ceramsite are inorganic solid wastes, and the inorganic solid wastes are sand washing mud, iron washing mud, and slag. It also includes additives less than 5%, and the additives are one or two of sodium salts or potassium salts, namely a mixture of sodium salts or / and potassium salts and manganese salts. Among the inorganic solid wastes, the total mass ratio of sand washing mud, iron washing mud, and slag is more than 95%, and the mass ratio of sand washing mud, iron washing mud, and slag is 2.6 - 3.5:1.8 - 2.1:1.2 - 2.8. The sand washing mud is the sand washing mud generated during the washing process of mountain sand in areas without river sand, sewage treatment mud, or silt in lakes / ponds; the iron washing mud is the iron washing mud generated during the beneficiation of iron ore by water; the slag is one or more of kaolin tailings slag, china clay ore slag, or manganese ore slag.

[0007] The invention patent with the publication number CN106242514A provides a composite solid waste lightweight and high-strength ceramsite and a preparation method thereof. It is mainly prepared from the following raw materials by weight: 40.0 - 60.0 parts of iron tailings; 10.0 - 15.0 parts of auxiliary raw materials; 0.1 - 3.0 parts of foaming agent; and it also includes sludge, and the content of dry-based sludge in the sludge is 30.0 - 50.0 parts. Its preparation method is: accurately weigh the sludge, iron tailings, auxiliary raw materials, and foaming agent according to the designed proportioning ratio and mix them evenly to form a uniform basic mixture; granulate and form to obtain ceramsite green bodies, and fire the ceramsite green bodies and anneal and cool them to obtain urban sludge collaborative iron tailings ceramsite.

[0008] However, the above-mentioned ceramsite or preparation method has the technical problem of uneven granulation.

[0009] In view of this, it is necessary to design an improved composite foamed ceramsite, its preparation method and application to solve the above problems. Summary of the Invention

[0010] The purpose of the present invention is to provide a composite foamed ceramsite, its preparation method and application.

[0011] To achieve the above-mentioned invention purpose, the present invention provides a composite foamed ceramsite, which is prepared by a composite system composed of ceramic blank, solid waste mud, and foaming agent mixed in a mass ratio of (20 - 80):(20 - 80):(1 - 16) through processes of mixing, granulating, drying, sintering, and cooling; The solid waste mud includes machine-made sand waste mud and aluminum anode mud in a mass ratio of (0 - 80):(0 - 80).

[0012] As a further improvement of the present invention, the ceramic blank comprises kaolin, feldspar, and quartz in a mass ratio of 3:2:4.

[0013] As a further improvement of the present invention, the foaming agent is starch, and the foaming agent accounts for 4-8% of the total amount of the ceramic blank and the solid waste sludge.

[0014] As a further improvement of the present invention, the preparation raw materials of the composite foamed ceramsite comprise a ceramic blank, machine-made sand waste sludge, and starch in a mass ratio of 50:50:4.

[0015] As a further improvement of the present invention, the preparation raw materials of the composite foamed ceramsite comprise a ceramic blank, aluminum anode sludge, and starch in a mass ratio of (20-80):(20-80):4.

[0016] As a further improvement of the present invention, the preparation raw materials of the composite foamed ceramsite comprise a ceramic blank, machine-made sand waste sludge, aluminum anode sludge, and starch in a mass ratio of 50:(1-49):(1-49):4.

[0017] To achieve the above-mentioned invention purpose, the present invention also provides a preparation method of the above-mentioned composite foamed ceramsite, which comprises the following steps: S1, pre-treat the raw materials, and then pre-mix the ceramic blank, the solid waste sludge composed of machine-made sand waste sludge and / or aluminum anode sludge, and the foaming agent starch with water in proportion to obtain a mixture; S2, add water and stir until the mixture has a certain viscosity and plasticity, then stop stirring, and perform pelletizing and forming treatment to obtain green ceramsite balls; S3, dry and sinter the made green ceramsite balls, wherein the sintering temperature is 1000°C - 1200°C, the sintering holding time is 1 - 4h, and the heating rate is 3 - 8°C / min to obtain finished ceramsite; S4, after the heat preservation ends, naturally cool the finished ceramsite, and when the temperature drops below 400°C, take out the ceramsite to obtain the composite foamed ceramsite.

[0018] As a further improvement of the present invention, the sintering temperature is 1050°C - 1150°C.

[0019] As a further improvement of the present invention, during the preparation process of the composite foamed ceramsite, the total amount of water added is within the range of 15% - 25% of the total amount of the raw materials.

[0020] To achieve the above-mentioned invention purpose, the present invention also provides the application of the above-mentioned composite foamed ceramsite in the fields of building lightweight aggregates, decorative materials, horticultural materials, and soil improvement.

[0021] The beneficial effects of the present invention are: 1. The composite foamed ceramsite provided by the present invention is a lightweight aggregate prepared from industrial waste mechanism sand waste mud and / or anode mud as the main raw materials through a process of adding a foaming agent. The mechanism sand waste mud and / or anode mud are by-products in the industrial production process, and it costs to treat and dispose of them. Converting them into ceramsite can reduce the waste treatment cost and environmental governance cost. At the same time, it can reduce the dependence on natural sand and gravel resources and save costs. Converting the mechanism sand waste mud / anode mud into useful ceramsite reduces the accumulation and landfill of waste, can reduce the environmental pollution caused by waste, and is conducive to sustainable development. The resource utilization of the mechanism sand waste mud / anode mud can reduce the exploitation of natural resources and is beneficial to the protection of the ecological environment.

[0022] 2. The preparation method of the composite foamed ceramsite provided by the present invention determines the optimal raw material ratio of the mechanism sand waste mud to the blank as 5:5 on the premise of ensuring the maximum resource utilization of solid waste. The incorporation amount of the foaming agent and the sintering temperature are also key factors affecting the performance of the ceramsite. It is studied and determined that the incorporation amount of the foaming agent is 4%, the sintering temperature is 1100 °C, and the heat preservation time is 2 h. The ceramsite raw material with a ratio of 5:5 can be made into foamed ceramsite with a firing shrinkage rate of 6.92%, a loss on ignition of 25.16%, a water absorption rate of 46.88%, an apparent porosity of 59.50%, a bulk density of 1.27 (g / cm 3 ) and a particle strength of 1.46 MPa. In addition, the performance of the foamed ceramsite made from aluminum foil anode mud as the raw material is compared, and the application fields of the two types of ceramsite are evaluated; it provides a new way for the resource utilization of the mechanism sand waste mud and has good economic and environmental benefits.

[0023] 3. The preparation method of the composite foamed ceramsite provided by the present invention directly mixes the mechanism sand waste mud and / or anode mud with the ceramic blank for granulation, without adding other binders and surfactants. Only a small amount of water is needed to achieve granulation. The process is simple, which is more conducive to the actual production of waste mud to make ceramsite, reduces production energy consumption, achieves better economic benefits, and the waste mud content can reach 50%, meeting the "sludge reduction". Through the study of the performance of waste mud to make foamed ceramsite, the influence of different waste mud incorporation amounts on the performance of waste mud to make foamed ceramsite and the relationship between different foaming agent incorporation amounts and the porosity, apparent density and water absorption rate of the ceramsite can be analyzed. The composite foamed ceramsite made from the mixture of mechanism sand waste mud and aluminum foil anode reaches a functional balance in terms of strength and water absorption rate. By adjusting the ratio of the two, the water absorption and strength of the ceramsite can be adjusted to meet different application requirements. Description of the Drawings

[0024] Figure 1 It is the morphology diagram of the foamed ceramsite samples made with different raw material ratios provided in Embodiments 1-7 of the present invention.

[0025] Figure 2 The whiteness values of the foamed ceramsite samples made from different raw material ratios provided in Embodiments 1-7 of the present invention.

[0026] Figure 3 The morphology diagrams of the foamed ceramsite samples made from different raw material ratios provided in Embodiments 8-14 of the present invention.

[0027] Figure 4 The whiteness values of the foamed ceramsite samples made from different raw material ratios provided in Embodiments 8-14 of the present invention.

[0028] Figure 5 The macroscopic morphology of the ceramsite samples made from different amounts of foaming agent incorporated in Embodiments 20-24 of the present invention.

[0029] Figure 6 The macroscopic morphology of the pressed ceramic samples made from different amounts of foaming agent incorporated in Embodiments 20-24 of the present invention.

[0030] Figure 7 The macroscopic morphology of the foamed ceramsite made from mechanism sand waste mud at different sintering temperatures in Embodiments 25-27 of the present invention.

[0031] Figure 8 The firing shrinkage rate and bulk density of the ceramsite at different sintering temperatures in Embodiments 25-27 of the present invention.

[0032] Figure 9 The water absorption rate and particle strength of the ceramsite at different sintering temperatures in Embodiments 25-27 of the present invention.

[0033] Figure 10 The macroscopic morphology of the foamed ceramsite made from aluminum foil anode mud at different sintering temperatures in Embodiments 28-30 of the present invention.

[0034] Figure 11 The influence of different sintering temperatures on the firing shrinkage rate and bulk density of the ceramsite in Embodiments 28-30 of the present invention.

[0035] Figure 12 The influence of different sintering temperatures on the water absorption rate and particle strength of the ceramsite in Embodiments 28-30 of the present invention. Detailed implementation manners

[0036] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0037] Here, it should also be noted that in order to avoid obscuring the present invention due to unnecessary details, only the structures and / or processing steps closely related to the solution of the present invention are shown in the drawings, while other details less related to the present invention are omitted.

[0038] In addition, it should be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or apparatus comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or apparatus.

[0039] Please refer to Figure 1 As shown, the present invention provides a method for preparing composite expanded ceramsite, which comprises the following steps: S1, pre-treat the raw materials, and then pre-mix the ceramic blank, the solid waste mud composed of machine-made sand waste mud and / or aluminum anode mud, and the foaming agent starch with water in proportion to obtain a mixture; S2, add water and stir until the mixture has a certain viscosity and plasticity, then stop stirring, and perform granulation and forming treatment to obtain green ceramsite balls; S3, dry and sinter the prepared green ceramsite balls, wherein the sintering temperature is 1000°C to 1200°C, the sintering holding time is 1 to 4 h, and the heating rate is 3 to 8°C / min to obtain finished ceramsite; S4, after the heat preservation is completed, naturally cool the finished ceramsite, and when the temperature drops below 400°C, take out the ceramsite to obtain composite expanded ceramsite.

[0040] Preferably, the sintering temperature is 1050°C to 1150°C.

[0041] Preferably, during the preparation process of the composite expanded ceramsite, the total amount of water added is in the range of 15% to 25% of the total amount of raw materials.

[0042] Test the ceramsite according to "Lightweight Aggregates and Their Test Methods" (GB / T 17431.1 - 2010).

[0043] (1) Apparent porosity, water absorption and bulk density Using the vacuum method, with a water absorption tester, put the sample into the instrument, the instrument automatically evacuates and completely immerses the sample in water, keep it for 60 min, take out the sample, wipe the surface moisture of the sample with a wet cloth, and weigh its wet weight and suspended weight. Calculate the apparent porosity, water absorption and bulk density of the sample from formula (2 - 1).

[0044] In the formula: Pa is the apparent porosity (%), Wa is the water absorption (%), D is the bulk density (g / cm3), m1 is the mass of the sample after drying (g), m2 is the suspended weight of the water-saturated sample (g), m3 is the mass of the water-saturated sample (g), ρ1 is the density of water (g / cm3), and in this experiment, ρ1 = 1 g / cm3 is taken.

[0045] (2)Bulk density Dry the ceramsite to constant weight, evenly pour the sample into the measuring cylinder, fill the surface voids with ceramsite of smaller particle size, and weigh it. Calculate the bulk density of the ceramsite according to Equation (2-4): In the formula, ρ0 is the bulk density (g / cm3), m4 is the total mass of the sample and the measuring cylinder (g), and m5 is the mass of the measuring cylinder (g).

[0046] (3)Firing shrinkage rate Use a vernier caliper to measure the diameters of the ceramsite samples before and after firing in three different directions, calculate the firing shrinkage of the ceramsite samples according to Equation (2-5), use a vernier caliper to measure the dimensions of the pressed ceramic samples before and after firing, and calculate the firing shrinkage rate of the samples according to Equation (2-5).

[0047] In the formula: S and Sd are the firing shrinkage rates (%), V1 is the volume of the sample before firing (mm3), and V2 is the volume of the sample after firing (mm3).

[0048] (4)Particle strength Take three ceramsites with similar shapes and sizes for testing to obtain their average strength values. Use a pressure testing machine model WDW-20E to measure the strength of individual ceramsite particles, and control the speed of applying pressure at 10 mm / min. Calculate the strength of individual ceramsite according to Equation (2-6): In the formula, Ps is the particle strength of the ceramsite sample (MPa), F is the load borne when the ceramsite fractures (N), and D is the diameter of the ceramsite (mm).

[0049] (5)Expansion rate To ensure the accuracy of the test results, theoretically, the samples should be processed into cylindrical shapes with a diameter of 20 mm and a thickness of 20 mm to ensure that all samples have a consistent volume before firing. In practice, due to manual errors, they are made into cylinders with a mass of 2.5 g and a diameter of 20.40 mm using a tablet press, and the expansion performance of the samples is characterized by Equation (2-7).

[0050] In the formula, EI is the expansion rate (%), V1 is the volume of the sample before firing, and V2 is the volume of the sample after firing.

[0051] (7)Whiteness Test the whiteness of the full-automatic whiteness meter for tablet pressing with the same experimental ratio. Generally, the ceramsite with higher whiteness has better decorative effect. In addition, due to insufficient sintering or excessive impurities, the surface color of the ceramsite will be darker and the whiteness will be lower. Therefore, the whiteness test can also indirectly reflect the sintering degree and impurity content of the ceramsite. Keep the sample surface clean, place the sample on the measuring port of the whiteness meter, and conduct the measurement to obtain the tristimulus values. Calculate the whiteness value according to formula (2-8).

[0052] In the formula, Wj is the whiteness value (%), and X, Y, and Z are the tristimulus values.

[0053] (8)Loss on ignition Loss on ignition refers to the percentage of the mass loss caused by high-temperature burning of the sample in the range of 1000 to 1100 °C after drying the sample at 105 to 110 °C, accounting for the total mass of the original dried sample. Weigh the mass of the ceramsite before and after firing with an electronic balance of model FA2204C, and calculate the loss on ignition of the sample according to formula (2-9).

[0054] In the formula, XLOI is the mass percentage of loss on ignition (%), m0 is the mass of the sample before burning (g), and m1 is the mass of the sample after loss on ignition (g).

[0055] Examples 1-7 Examples 1-7 of the present invention provide a preparation method of composite foamed ceramsite, including the following steps: (1)Mix in proportion Prepare raw materials, weigh appropriate amounts of ceramic blank, machine-made sand waste mud, starch and other raw materials. Prepare ceramsite according to the mass ratio of ceramic blank to machine-made sand waste mud of 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8. Select starch as the foaming agent, and the addition amount is 4%; the raw material ratio table is shown in Table 1. The numbers of Examples 1-7 are A82, A73, A64, A55, A46, A37, A28.

[0056] (2)Granulation and forming Weigh the raw materials according to a certain ratio, and add water and stir evenly. The amount of added water is adjusted according to the ratio of the raw materials. It is found through experiments that the added water is in the range of 15% - 25%. When the mixture has a certain viscosity and plasticity, stop stirring. Take an appropriate amount of raw materials for manual granulation. Slightly moisten the palm before rubbing the ceramsite by hand to facilitate better forming. Rub the mixture into ceramsite with an approximately spherical shape, smooth surface, and no obvious cracks.

[0057] (3)Drying and sintering Put the prepared green pellets of ceramsite into a forced-air drying oven and dry them at 100 °C for 2 h. Place the ceramsite in a muffle furnace, set the sintering temperature at 1100 °C, the sintering holding time at 2 h, and the heating rate at 5 °C / min to obtain the finished ceramsite product.

[0058] (4)Cooling When the holding time ends, the ceramsite is naturally cooled in the muffle furnace. After the temperature in the furnace drops below 400 °C, take out the ceramsite.

[0059] Comparative Example 1 The difference from Example 1 is that no machine-made sand waste mud is added.

[0060] Table 1 shows the raw material compositions and ratios of Examples 1-7 Examples 8-14 Examples 8-14 of the present invention provide a method for preparing composite expanded ceramsite, which includes the following steps: (1)Mixing in proportion Prepare the raw materials, weigh appropriate amounts of ceramic blank, aluminum foil anode mud, starch and other raw materials. Prepare ceramsite according to the mass ratio of ceramic blank to aluminum foil anode mud of 8:2, 7:3, 6:4, 5:5, 4:6, 3:7, 2:8. Select starch as the foaming agent, and the addition amount is 4%; the raw material ratio table is shown in Table 2. The numbers of Examples 8-14 are I82, I73, I64, I55, I46, I37, I28.

[0061] (2)Pelletizing and forming Weigh the raw materials according to a certain proportion, and add water and stir to mix evenly.

[0062] The amount of added water is adjusted according to the proportion of the raw materials. It is found through experiments that the added water is in the range of 25% - 30%. When the mixture has a certain viscosity and plasticity, stop stirring. Take an appropriate amount of the raw materials for manual pelletizing. Slightly moisten the palm before rubbing the ceramsite by hand so as to better form it. Rub the mixture into ceramsite with a shape approximately spherical, smooth surface and no obvious cracks.

[0063] (3)Drying and sintering Put the prepared green pellets of ceramsite into a forced-air drying oven and dry them at 100 °C for 2 h. Place the ceramsite in a muffle furnace, set the sintering temperature, the sintering holding time at 2 h, and the heating rate at 5 °C / min to obtain the finished ceramsite product.

[0064] (4)Cooling When the holding time ends, the ceramsite is naturally cooled in the muffle furnace. After the temperature in the furnace drops below 400 °C, take out the ceramsite.

[0065] Table 2 shows the raw material compositions and ratios of Examples 8-14 Examples 15 - 19 At a firing temperature of 1100 °C, a heat preservation time of 2 h, and a ratio of machine-made sand waste mud to ceramic blank of 5:5, a single variable was set. By incorporating different foaming agent contents, the influence on the properties of ceramsite was analyzed. The contents of the foaming agent are shown in Table 3, and the numbers of Examples 15 - 19 are: A00, A04, A08, A12, A16.

[0066] Table 3 shows the settings of the foaming agent content in Examples 15 - 19 Examples 20 - 24 At a firing temperature of 1100 °C, a heat preservation time of 2 h, and a ratio of anode mud to ceramic blank of 5:5, a single variable was set. By incorporating different foaming agent contents, the influence on the properties of ceramsite was analyzed. The incorporation amounts of the foaming agent are 0%, 4%, 8%, 12%, and 16% respectively. The contents of the foaming agent are shown in Table 3, and the numbers of Examples 20 - 24 are: I00, I04, I08, I12, I16.

[0067] Table 4 shows the settings of the foaming agent content in Examples 15 - 19 Examples 25 - 27 The sintering temperature has a great influence on the properties of ceramsite. A relatively low sintering temperature will result in insufficient sintering of the ceramsite and low strength, while an excessively high sintering temperature will cause internal collapse of the ceramsite, resulting in melting and bonding. To study the influence of the sintering temperature on the properties of ceramsite, with a ratio of machine-made sand waste mud to blank raw materials of 5:5, starch was selected as the foaming agent with an addition amount of 4%, and ceramsite samples were prepared. The three set sintering temperatures were 1050 °C, 1100 °C, and 1150 °C respectively, and the sintering time was 2 h. The main properties of the ceramsite finished products were compared and analyzed.

[0068] Examples 28 - 30 The three set sintering temperatures were 1050 °C, 1100 °C, and 1150 °C respectively. At different sintering temperatures, with a ratio of aluminum foil anode mud to blank raw materials of 5:5, starch was selected as the foaming agent with an addition amount of 4%, and ceramsite samples were prepared.

[0069] Examples 31 - 33 The difference from Example 4 is that the solid waste mud uses a mixture of machine-made sand waste mud and anode mud.

[0070] The ratio of machine-made sand waste mud to anode mud is 20:80, 50:50, 80:20. The foamed ceramsite was prepared according to the preparation method in the example.

[0071] Table 5 shows the proportion settings of manufactured sand waste mud and anode mud in Examples 31 - 33 Preparation of tablet ceramics In Examples 1 - 30, the raw materials were grouped according to the experimental ratio scheme. 2.5 g of the sample was weighed, a pressing mold with a diameter of 20.40 mm was selected, and it was pressed into shape with an electric tablet press. The maximum pressure was set to 15 KN, and the pressing holding time was 1 min.

[0072] The performance of the foamed ceramsite prepared in the above examples was measured.

[0073] I. Influence of different waste solid muds and their ratios on the performance of ceramsite ① Manufactured sand waste mud Under the conditions of a firing temperature of 1100 °C, a heat preservation time of 2 h, and a foaming agent incorporation amount of 4%, the main properties of the ceramsite samples made according to different ratios of manufactured sand waste mud to the blank are shown in Table 5.

[0074] Table 6 shows the main properties of the ceramsite samples made from different ratios of manufactured sand waste mud to the blank in Examples 1 - 7 The chemical compositions and physical properties of different raw materials will affect the pore structure of ceramsite, and different raw material ratios will affect the performance of the samples. It can be analyzed from Table 5 that as the proportion of manufactured sand waste mud in the raw materials increases, a large amount of calcium carbonate is contained in the manufactured sand. During the firing process, calcium carbonate decomposes when heated, generating gas, which causes pores to form inside the ceramsite and the volume to expand, thus continuously reducing the firing shrinkage rate. In addition, there may be organic substances in the manufactured sand waste mud, and these organic substances decompose at high temperatures, resulting in an increase in the loss on ignition. The gas generated inside the ceramsite is wrapped by the generated liquid phase, forming a large number of pores, reducing the density of the ceramsite, so the porosity of the ceramsite increases and the bulk density decreases.

[0075] As the proportion of manufactured sand waste mud continues to increase, the internal structure of the ceramsite gradually becomes loose and the density decreases. Therefore, the particle strength of the ceramsite continuously decreases. The ratio of manufactured sand waste mud to the blank of the ceramsite numbered A73 in Example 2 is 7:3, the ratio of manufactured sand waste mud to the blank of the ceramsite numbered A64 in Example 3 is 6:4, and the ratio of manufactured sand waste mud to the blank of the ceramsite numbered A55 in Example 4 is 5:5. The firing shrinkage rates of these three ceramsite samples are contrary to the regular pattern. This may be due to measuring the diameters of the spherical ceramsite before and after firing in three random directions with a vernier caliper and then calculating its volume, resulting in measurement errors. In addition, the manufactured sand waste mud, the blank, and the starch may not be evenly mixed during the mixing process, leading to local foaming of the sample and an increase in volume, thus resulting in a lower shrinkage rate for these three ceramsites.

[0076] Due to the certain differences in the external forces applied to the ceramsite made by hand-kneading in all directions, the sphere is irregular, and there are likely to be errors in measuring the diameters of the ceramsite before and after firing. Therefore, for the same raw material ratio, the tablet ceramics made with different raw material ratio incorporation amounts are also subjected to performance test analysis and comparison to further verify the influence of different raw material ratios on the prepared ceramsite samples.

[0077] As can be seen from Table 7, the samples with a higher content of manufactured sand have higher porosity and water absorption. At the same time, their bulk density is lower and their compressive strength is lower. When the content of ceramic billet is higher, the minerals in the billet react with the silicate minerals in the manufactured sand waste mud to form strong chemical bonds, and the samples have higher compressive strength, which is consistent with the above law.

[0078] Table 7 shows the main properties of the tablet ceramic samples made with different raw material ratios in Examples 1-7 From Figure 1 it can be observed that the more the proportion of the billet in the ceramsite sample, the darker yellow the sample color is. As the proportion of the manufactured sand waste mud increases, the sample color tends to be light yellow. The whiteness of the corresponding tablet ceramics is tested, and the test results are as Figure 2 shown, which is consistent with the morphological observation. This is because the chemical composition of the manufactured sand waste mud contains more calcium oxide and quartz, and partial melting occurs during sintering at high temperature, promoting the formation of the glass phase, which can reduce the scattering of light, thereby improving the gloss and whiteness of the ceramsite surface.

[0079] ② Aluminum foil anode mud Under the conditions of a firing temperature of 1100 °C, a holding time of 2 h, and a foaming agent incorporation amount of 4%, the main properties of the ceramsite samples made with different ratios of aluminum foil anode mud to billet are shown in Table 8, and the sample morphology is as Figure 3 shown.

[0080] Table 8 shows the main properties of the ceramsite samples made with different raw material ratios in Examples 8-14 It can be analyzed from Table 8 that the aluminum foil anode mud is mainly composed of alumina. Alumina has good thermal stability, with a small coefficient of thermal expansion at high temperatures and is not prone to volume changes. As the proportion of aluminum foil anode mud in the raw materials increases, the shrinkage rate of the sample should decrease or remain unchanged. However, the ceramsite in Example 13 numbered 137 and Example 14 numbered 128 had a large shrinkage, probably because the aluminum foil anode mud contains some impurities or organic substances, which react with certain components in the blank, causing internal collapse and volume shrinkage, thus increasing the firing shrinkage rate. When measuring the diameters of the ceramsite before and after firing, it was manually measured, and the spherical shape of the ceramsite made by manual granulation is irregular, so there may be measurement errors. Since some components in the aluminum foil anode mud will produce some gases during the firing process, or react with the components in the ceramic blank to produce gases, as the incorporation amount of the aluminum foil anode mud increases, the amount of gas also increases, resulting in an increase in the porosity of the escaping interior. These pores can provide storage space for moisture, increasing the water absorption rate of the ceramsite. And the pores occupy the volume originally belonging to solid substances, so the bulk density of the ceramsite continuously decreases. The presence and quantity of pores will reduce the strength of the ceramsite. As the incorporation ratio of the anode mud increases, the strength of the ceramsite particles made thereof continuously decreases.

[0081] Since there are certain differences in the external forces applied in all directions to the ceramsite made by manual kneading, and the spherical shape is irregular, there are likely to be errors in measuring the diameters of the ceramsite before and after firing. Therefore, for the same ratio of raw materials, the performance test analysis and comparison of the tableted ceramics made with different incorporation amounts of raw material ratios are carried out to further verify the influence of different raw material ratios on the made ceramsite samples. The main properties of the tableted ceramic samples made with different raw material ratios are shown in Table 9.

[0082] Table 9 shows the main properties of the tableted ceramic samples made with different raw material ratios in Examples 8 - 14 It can be seen from Table 9 that the samples with a higher content of aluminum foil anode mud have a higher porosity and water absorption rate, and at the same time, their bulk density is lower. When the ratio of aluminum foil anode mud to the blank in the raw materials is different, the compressive strength of the made ceramsite samples is about 5 MPa. Using a pressure testing machine to conduct a pressure test on the tableted samples made of pure aluminum foil anode mud, the load when the sample was fractured was measured to be 1536 N, and the calculated compressive strength of the sample was 6.88 MPa. It can be guessed that the compressive strength of the aluminum foil anode mud and the blank is close to 5 MPa. No matter how the incorporation amounts of the two change, the compressive strength of the ceramsite samples fluctuates around this value. Since the samples are formed under a large pressure and are dense inside, the shrinkage rate, water absorption rate, porosity, bulk density, and compressive strength of the fired sheet-like samples do not change much.

[0083] From Figure 3It can be found that as the content of aluminum foil anode mud in the raw materials increases, the color of the sample tends to be white. The more the billet content, the more the sample tends to be yellow. By observing the surface of the ceramsite samples, it can be found that when the content of aluminum foil anode mud in the sample is relatively high, its surface is relatively rough, showing a "pitted" shape with many pores. It can be speculated that during the sintering process, less liquid phase is generated, and some gases are not wrapped and overflow from the sample. Using a full-automatic whiteness meter to test the corresponding pressed ceramics, the test results are as Figure 4 shown, which is consistent with the morphological observation.

[0084] II. Influence of Different Incorporation Amounts of Foaming Agents on the Properties of Ceramsite ① Mechanism sand waste mud At a firing temperature of 1100 °C, a holding time of 2 h, and a ratio of mechanism sand waste mud to billet of 5:5, setting a single variable, the influence of different incorporation amounts of foaming agents on the properties of ceramsite was analyzed. Its main properties are shown in Table 10.

[0085] Table 10 shows the main properties of ceramsite samples made with different incorporation amounts of foaming agents in Examples 15 - 19 Starch was selected to prepare lightweight foamed ceramsite. Its foaming mechanism is mainly that starch first undergoes gelatinization during heating. As the temperature further increases, the starch molecular chains break, releasing water vapor and carbon dioxide. These gases can generate a large number of bubbles inside the ceramsite. As the sintering reaction proceeds, there is a large amount of liquid phase inside the sample. Under the action of atmospheric pressure, the bubbles are wrapped and fixed in the ceramic matrix by the liquid phase, thus forming the porous foamed structure of the sample. The porosity, bulk density, particle strength, etc. of the foamed ceramsite can be adjusted by adjusting the incorporation amount of starch and the sintering conditions. Too much incorporation amount of starch may cause the bubbles to be too large and burst, affecting the properties of the ceramsite sample.

[0086] As can be seen from Table 10, since there will be a certain volume shrinkage during the sintering process of the samples, and with the increase of the foaming agent content, the firing shrinkage rate of the ceramsite samples gradually decreases, indicating that the foaming effect of the ceramsite samples is continuously enhanced. With the increase of the foaming agent content, a large amount of gas is generated during the sintering process of the ceramsite samples, resulting in a continuous increase in the loss on ignition. During the sintering process, a liquid phase is continuously formed in the ceramsite samples, wrapping the generated gas, so there are a large number of pores inside the samples, making them have a large water absorption rate and apparent porosity. Similarly, the bulk density of the ceramsite samples also continuously decreases. When the doping amount of the foaming agent is small, the amount of generated gas is not enough to form an ideal pore structure. The firing shrinkage rate of the ceramsite without adding a foaming agent is 8.19%. On this basis, the foaming effect of the foaming agent can be observed from the decrease of the firing shrinkage rates of Examples 16 - 19 numbered A04, A08, A12, and A16. The ceramsite sample with 16% starch added has the highest water absorption rate, which is 63.66%, and the smallest bulk density, which is 1.06 g / cm 3 , but correspondingly, the particle strength of A16 is the lowest.

[0087] Since there are certain differences in the external forces applied in all directions to the ceramsite made by hand kneading, the sphere is irregular, and there are easily errors in measuring the diameters of the ceramsite before and after firing. Therefore, for the raw materials with the same ratio, the performance tests and analyses of the tablet ceramics made with different doping amounts of the foaming agent are also carried out for comparison to further verify the influence of different doping amounts of the foaming agent on the made ceramsite samples.

[0088] Table 11 shows the main properties of the tablet ceramic samples made with different doping amounts of the foaming agent in Examples 15 - 19 As can be seen from Table 11, with the increase of the doping amount of the foaming agent, the firing shrinkage rate of the samples continuously decreases. The firing shrinkage rate of Example 17 numbered A08 is 0%, indicating that there is no volume change (or extremely small volume change) during its sintering process. The firing shrinkage rate of the ceramsite sample of Example 19 numbered A16 is negative, indicating that more gas is generated during its sintering process and the volume expands. The compressive strength of the tablet ceramic samples made with different doping amounts of the foaming agent changes little. Maybe because when the pressure testing machine conducts the sample pressure strength test on the samples, when the samples reach or exceed their maximum fracturing degree, in order to ensure the accuracy and integrity of the data, the testing machine will still continue to apply pressure at a constant loading rate until the test ends. Therefore, there are errors in the acting force when the measurer fractures the samples.

[0089] ② Aluminum foil anode slime When the firing temperature is 1100°C, the heat preservation time is 2h, and the ratio of aluminum foil anode mud to blank is 5:5, a single variable is set, and the influence of different foaming agent contents on the properties of ceramsite is analyzed. The incorporation amounts of the foaming agent are 0%, 4%, 8%, 12%, and 16% respectively. The main properties of the ceramsite samples made with different incorporation amounts of the foaming agent are shown in Table 11.

[0090] Table 12 shows the main properties of the ceramsite samples made with different incorporation amounts of the foaming agent in Examples 20 - 24. As can be seen from Table 12, as the starch content of the foaming agent continuously increases, larger pores are formed inside, thereby reducing the firing shrinkage rate. During the sintering process, the foaming agent and other substances volatilize from the ceramsite, leaving pores inside the sample. These pores provide channels for water molecules to enter, resulting in higher water absorption and porosity of the ceramsite sample. There are a large number of pores inside the ceramsite sample, making the structure relatively loose, reducing its bulk density and particle strength. Due to the relatively low particle strength, the change in particle strength is small with different incorporation amounts of the foaming agent.

[0091] For raw materials with the same ratio, the performance tests and analyses are also carried out on the tablet ceramics made with different incorporation amounts of the foaming agent for comparison to further verify the influence of different incorporation amounts of the foaming agent on the prepared ceramsite samples.

[0092] Table 13 shows the main properties of the tablet ceramic samples made with different incorporation amounts of the foaming agent in Examples 20 - 24. As can be seen from Table 13, as the incorporation amount of the foaming agent increases, the water absorption, loss on ignition, and bulk density of the sample increase significantly in turn, indicating that the foaming effect of the foaming agent is normal. The volume shrinks instead because a large number of pores are generated inside the ceramsite, resulting in the collapse inside the sample. During the sintering process, a liquid phase is continuously generated, causing internal melting and bonding, and the volume decreases. Observe the macroscopic morphology of the sample as Figures 5-6 shown.

[0093] III. Influence of Different Sintering Temperatures on the Properties of Ceramsite In Examples 25 - 27, by Figure 7It can be seen that when the sintering temperature is 1050 °C and the sintering temperature is relatively low, the surface of the ceramsite is relatively rough and brownish. At this time, the liquid phase is less and not enough to wrap the released gas, and there are obvious pores on the surface of the sample. When the sintering temperature is increased to 1100 °C, a small amount of enamel layer is formed on the surface of the ceramsite, the surface is relatively smooth, and at the same time, a small amount of gas breaks through the surface to form pores, and the open pores on the surface are relatively reduced. When the sintering temperature continues to increase to 1150 °C, an enamel layer with a certain thickness and luster is formed on the surface, and the color is dark brown. Due to the increase in the liquid phase, the pores formed on the surface of the ceramsite sample at low temperature are blocked, and the sample shows a slight bonding phenomenon. The ceramsite is underfired at 1050 °C and overfired at 1100 °C.

[0094] It can be seen from Figure 8 and 9 that as the sintering temperature increases, the shrinkage rate of the ceramsite sample gradually decreases. This shows that within the studied temperature range, increasing the sintering temperature can increase the liquid phase amount of the ceramsite during sintering, and then form an enamel layer on the surface of the ceramsite. The higher the temperature, the thicker the enamel layer, and even the ceramsites are bonded; the enamel layer can play a role in hydrophobic and water isolation, reducing the water absorption rate of the ceramsite. When the sintering temperature is 1050 °C, the water absorption rate of the ceramsite sample is relatively high compared to the other two groups because the sintering is insufficient, the generated liquid phase is insufficient, the surface is relatively rough, and there are a large number of pores, resulting in a high water absorption rate of the ceramsite, and the internal structure is loose and the particle strength is low. When the sintering temperature is 1100 °C, the enamel layer on the surface of the sample is thicker, making the particle strength of the sample higher. On the premise of ensuring better performance of the ceramsite sample, the optimal sintering temperature is selected as 1100 °C and the sintering time is 2 h.

[0095] In Examples 28 - 30, it can be observed that Figure 10 when the sintering temperature is 1050 °C and the sintering temperature is relatively low, the surface of the ceramsite is relatively rough and the color is lighter. At this time, the liquid phase is less and not enough to wrap the released gas, and there are obvious pores on the surface of the sample. When the sintering temperature is increased to 1100 °C, a small amount of enamel layer is formed on the surface of the ceramsite, the surface is relatively smooth, and at the same time, a small amount of gas breaks through the surface to form pores, and the open pores on the surface are relatively reduced. When the sintering temperature continues to increase to 1150 °C, the surface of the sample turns black, the ceramsite melts, and an enamel layer appears on the surface. The ceramsite is underfired at 1050 °C and overfired at 1100 °C.

[0096] It can be seen from Figure 11 and 12It can be seen that when the sintering temperature is 1050 °C, the sintering is insufficient, the interior of the ceramsite is loose and there are many pores, and there are obvious pores on the surface of the sample, which makes it easy for the liquid to enter the interior of the ceramsite, resulting in a higher water absorption rate. At this time, the particle strength is relatively low. When the sintering temperature is 1150 °C, the sintering is too high, resulting in the collapse of the interior of the ceramsite, melting and bonding, and the volume of the sample after firing is small, the firing shrinkage rate is large, and the bulk density is large.

[0097] Due to the generation of liquid phase during the sintering process, the pores generated by the ceramsite at low temperature are blocked, and bonding occurs. There is an enamel layer with a certain thickness on the surface of the sample, which reduces the water absorption rate of the ceramsite sample and increases the particle strength. On the premise of ensuring good performance of the ceramsite sample, the optimal sintering temperature is selected as 1100 °C and the sintering time is 2 h.

[0098] Table 14 shows the main properties of the ceramsite samples made from different proportions of mechanism sand waste mud and anode mud in Examples 31 - 33 In Examples 31 - 33, the mechanism sand waste mud and aluminum foil anode mud are mixed as composite solid waste mud, and their influence on the properties of the foamed ceramsite is as follows: the composite ratio of the mechanism sand waste mud and the aluminum foil anode mud will affect both the water absorption performance and the particle strength. The mechanism sand waste mud and the aluminum foil anode mud can interact synergistically in this preparation system, enabling the water absorption rate and strength to change in a balanced manner to a certain extent. Therefore, by simultaneously controlling the water absorption performance and strength performance, different application requirements can be met.

[0099] The present invention uses mechanism sand waste mud / anode mud and blank as raw materials, and incorporates starch as a foaming agent to prepare foamed ceramsite. Factors such as the preparation process parameters, different raw material ratios, and the incorporation amount of the foaming agent have different effects on the properties of the foamed ceramsite.

[0100] (1) Different ratios of mechanism sand waste mud and blank in the raw materials have a certain impact on the properties of the ceramsite. To ensure the maximum utilization of resources and make the incorporation amount of mechanism sand waste mud as large as possible, the ratio of mechanism sand waste mud:blank = 5:5 is selected. At this time, the particle strength is relatively high, the water absorption rate is relatively high, and the properties of the ceramsite are good.

[0101] (2) Different incorporation amounts of the foaming agent have a certain impact on the properties of the ceramsite. As the incorporation amount increases, the water absorption rate of the ceramsite increases and the particle strength decreases. On the premise of ensuring the properties of the ceramsite while reducing costs, the incorporation amount of the starch foaming agent is selected as 4%. At this time, the firing shrinkage rate is 6.92%, the loss on ignition is 25.16%, the water absorption rate is 46.88%, the apparent porosity is 59.50%, the bulk density is 1.27 (g / cm3), and the particle strength is 1.46 MPa.

[0102] (3) The sintering temperature has a certain influence on the properties of ceramsite. Using the ceramsite raw material with the mix ratio of machine-made sand waste mud: blank = 5:5, within the range of 1050 - 1150 °C, when the sintering temperature is relatively low, the sintering is insufficient, the surface is rough and there are obvious pores, the water absorption rate is relatively high, and the particle strength is relatively low; when the sintering temperature is relatively high, the interior of the sample collapses, the interior of the ceramsite melts and bonds, a glaze layer is formed on the surface, the water absorption rate is relatively low, and the particle strength is high. Selecting the sintering temperature of 1100 °C and the sintering time of 2 h, ceramsite with a particle strength of 1.46 MPa, a water absorption rate of 46.88%, a porosity of 59.50%, and a bulk density of 1.269 g / cm3 can be fired. Therefore, using machine-made sand waste mud to produce ceramsite is a feasible way to treat solid waste.

[0103] (4) Selecting machine-made sand waste mud and aluminum foil anode mud alone or simultaneously to prepare ceramsite with the blank ratio, comparing three types of ceramsite, it is found that the particle strength of the ceramsite made of machine-made sand waste mud is generally higher than that of the ceramsite made of aluminum foil anode mud, while the water absorption rate of the latter is generally higher than that of the former. Therefore, the ceramsite made of machine-made sand waste mud tends to be used as a lightweight aggregate in building materials, while the ceramsite made of aluminum foil anode mud can be applied to decorative materials and horticultural materials due to its high whiteness, light weight, and high water absorption rate. For the third type of composite ceramsite made of a mixture of machine-made sand waste mud and aluminum foil anode, its strength and water absorption rate reach a functional balance. By adjusting the ratio of the two, the water absorption and strength of the ceramsite can be adjusted to meet different application requirements.

[0104] In summary, the present invention provides a composite foamed ceramsite and its preparation method and application. Using industrial waste machine-made sand waste mud and / or anode mud as the main raw materials, a lightweight aggregate prepared through a process by adding a foaming agent. And machine-made sand waste mud and / or anode mud itself are by-products in the industrial production process, which need to cost for their treatment and disposal. Converting them into ceramsite can reduce the waste treatment cost, lower the environmental governance cost, and at the same time reduce the dependence on natural sand and gravel resources and save costs. Converting machine-made sand waste mud / anode mud into useful ceramsite reduces the accumulation and landfill of waste, can reduce the environmental pollution caused by waste, and is conducive to sustainable development. The resource utilization of machine-made sand waste mud / anode mud can reduce the exploitation of natural resources and is beneficial to the protection of the ecological environment.

[0105] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A composite foamed ceramsite, characterized in that: The composite system composed of ceramic blank, solid waste mud, and foaming agent in a mass ratio of (20~80):(20~80):(1~16) is prepared through the processes of mixing, granulation, drying, sintering, and cooling; The solid waste mud includes machine-made sand waste mud and aluminum anode mud in a mass ratio of (0~80):(0~80).

2. The composite foamed ceramsite according to claim 1, wherein: The ceramic blank includes kaolin, feldspar, and quartz in a mass ratio of 3:2:

4.

3. The composite expanded ceramsite according to claim 1, wherein: The foaming agent is starch, and the foaming agent accounts for 4~8% of the total amount of the ceramic blank and the solid waste mud.

4. The composite expanded ceramsite according to claim 3, wherein: The raw materials for preparing the composite foamed ceramsite include ceramic blank, machine-made sand waste mud, and starch in a mass ratio of 50:50:

4.

5. The composite expanded ceramsite according to claim 3, characterized in that: The raw materials for preparing the composite foamed ceramsite include ceramic blank, aluminum anode mud, and starch in a mass ratio of (20~80):(20~80):

4.

6. The composite expanded ceramsite according to claim 3, wherein: The raw materials for preparing the composite foamed ceramsite include ceramic blank, machine-made sand waste mud, aluminum anode mud, and starch in a mass ratio of 50:(1~49):(1~49):

4.

7. The preparation method of the composite foamed ceramsite according to any one of claims 1 to 6, characterized in that: It includes the following steps: S1, Pretreat the raw materials, and then pre-mix the ceramic blank, the solid waste mud composed of machine-made sand waste mud and / or aluminum anode mud, and the foaming agent starch in proportion with pre-added water to obtain a mixture; S2, Add water and stir until the mixture has a certain viscosity and plasticity, then stop stirring, and perform granulation and forming treatment to obtain green ceramsite balls; S3, Dry and sinter the prepared green ceramsite balls. Among them, the sintering temperature is 1000°C~1200°C, the sintering holding time is 1~4h, and the heating rate is 3~8°C / min to obtain finished ceramsite; S4, After the heat preservation is completed, naturally cool the finished ceramsite. When it cools below 400°C, take out the ceramsite to obtain the composite foamed ceramsite.

8. The preparation method of the composite foamed ceramsite according to claim 7, characterized in that: The sintering temperature is 1050°C~1150°C.

9. The preparation method of the composite foamed ceramsite according to claim 7, wherein: During the preparation process of the composite foamed ceramsite, the total amount of water added is in the range of 15%~25% of the total amount of the raw materials.

10. Use of the composite expanded ceramsite according to any one of claims 1 to 6, or use of the method for preparing the composite expanded ceramsite according to any one of claims 7 to 9, characterized in that: Applications in the fields of building lightweight aggregates, decorative materials, horticultural materials, and soil improvement.

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