Solid waste-based porous glass ceramic as well as preparation method and application thereof

Abstract

The invention provides solid waste-based porous glass ceramic as well as a preparation method and application thereof, and belongs to the technical field of solid waste utilization. Comprising the following steps: (1) mixing a foaming agent A and a foaming agent B, and carrying out primary ball milling to obtain a composite foaming agent; and (2) mixing the composite foaming agent obtained in the step (1) with solid waste, carrying out secondary ball milling, and sintering to obtain the solid-waste-based porous glass ceramic. The composite foaming agent is adopted for foaming, the two components are subjected to a high-temperature deoxidation reaction and a high-temperature oxidation reaction respectively, the evenly-mixed composite foaming agent can be obtained through pre-ball-milling mixing, the composite foaming agent and the solid waste are evenly mixed in combination with secondary ball milling, and overgrowth of bubbles can be effectively prevented; the preparation method has the advantages that the uniformity and dispersity of the pore structure of the sample are further improved, so that the mechanical property of the porous glass ceramic is improved, only simple ball-milling mixing is needed, then primary sintering is carried out, melting, foaming and sintering are carried out simultaneously, and the process is simpler.

Description

[0001] This application is a divisional application of the invention patent filed on June 15, 2023, with application number 202310706561.2 and invention title "A Solid Waste-Based Porous Glass-Ceramic and Its Preparation Method and Application". Technical Field

[0002] This invention relates to the field of solid waste utilization technology, and in particular to a solid waste-based porous glass ceramic, its preparation method, and its application. Background Technology

[0003] Mining solid waste is a type of industrial solid waste, mainly including waste generated during mining and approximately 20%-30% of slag, dust, scraps, and waste mud generated during subsequent beneficiation, cutting, polishing, and other deep processing. Due to its large volume, complex composition, difficulty in treatment, and difficulty in utilization, it has become a major environmental challenge. Its treatment methods are limited, mainly landfilling, stockpiling, or discharge into rivers. A small portion of solid waste is recycled within the process, such as being used as roadbed base material or filler. A large amount of solid waste scraps not only fail to be used rationally but also cause great harm to the environment. Limited recycling cannot fundamentally solve the problem of solid waste pollution. Utilizing solid waste to prepare high-value new materials has become an important way to realize its resource utilization and recycling.

[0004] Solid waste contains abundant silica and alumina, along with trace amounts of alkaline oxides, making it an ideal raw material for preparing glass ceramics. Glass ceramics, also known as microcrystalline glass, are composite materials of crystalline and glassy phases, combining the advantages of both glass and ceramics. They possess superior properties such as high mechanical strength, adjustable thermal expansion, thermal shock resistance, chemical corrosion resistance, and low dielectric loss. Their thermal, chemical, biological, optical, and electrical properties often surpass those of metals and organic polymers. Utilizing solid waste and other waste materials as primary raw materials to prepare high-performance glass ceramic materials can significantly increase product added value, reduce production costs, and generate substantial economic and social benefits.

[0005] Existing methods for preparing porous glass ceramics mainly include melting, sintering, sol-gel, extrusion molding, foaming, gel casting, freeze-drying, pore-forming agent methods, and secondary forming methods. These methods require high-temperature water quenching, high-pressure forming, and secondary sintering, resulting in complex processes, long production cycles, high equipment requirements, and high energy consumption. These methods have many limitations for industrial production. Furthermore, commonly used foaming agents are generally carbonates, leading to poor mechanical properties in the prepared porous glass ceramics. Therefore, there is an urgent need for a simple yet high-performance method for preparing porous glass ceramics. Summary of the Invention

[0006] The purpose of this invention is to provide a solid waste-based porous glass-ceramic, its preparation method, and its applications. The preparation method provided by this invention is simple, and the prepared porous glass-ceramic exhibits excellent mechanical properties.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing solid waste-based porous glass ceramics, comprising the following steps: (1) Foaming agent A and foaming agent B are mixed and ball-milled once to obtain a composite foaming agent; foaming agent A includes one or more of manganese dioxide, titanium dioxide, ferric oxide and copper oxide; foaming agent B includes one or more of silicon carbide, silicon nitride, boron nitride, titanium carbide and titanium nitride; the mass ratio of foaming agent A to foaming agent B is (0.1~10):1; (2) The composite foaming agent obtained in step (1) is mixed with solid waste and then ball-milled twice. The mixture is then placed in a mold for sintering to obtain solid waste-based porous glass ceramics. The mold has a three-layer structure, consisting of a composite layer 1, a filling layer 2, and an inner layer 3 from the outside in. The composite layer 1 and the inner layer 3 are made of polycrystalline aluminosilicate fiber paper. The filling layer 2 is filled with alumina ceramic balls or zirconia ceramic balls with a diameter of 1.5~3.2mm. The thickness of the inner layer 3 is half the thickness of the composite layer 1. The pores in the solid waste-based porous glass ceramic are closed-cell structures.

[0008] Preferably, the mass of the composite foaming agent in step (2) is 0.25~3% of the solid waste mass.

[0009] Preferably, the solid waste in step (2) includes one or more of granite cutting slag and coal gangue.

[0010] Preferably, the mass content of silicon dioxide and aluminum oxide in the granite cutting slag and coal gangue is independently ≥80%, and the mass content of ferric oxide is independently ≥1.5%.

[0011] Preferably, the solid waste includes waste glass.

[0012] Preferably, the mass content of waste glass in the solid waste is 0.1% to 5%.

[0013] Preferably, the ball-to-material ratio in the first ball milling is (10~30):1; The ball-to-material ratio for the secondary ball milling is (2~4):1.

[0014] Preferably, the sintering temperature in step (2) is 1050~1200℃ and the sintering time is 60~180min.

[0015] This invention provides a solid waste-based porous glass ceramic prepared by the preparation method described in the above technical solution.

[0016] The present invention also provides the application of the solid waste-based porous glass ceramics described in the above technical solution in the fields of thermal, chemical, biological, optical and electrical engineering.

[0017] This invention provides a method for preparing porous glass ceramics based on solid waste. The invention employs a composite foaming agent for foaming. Foaming agent A undergoes a high-temperature deoxidation reaction, while foaming agent B undergoes a high-temperature oxidation reaction. Pre-mixing via ball milling yields a uniformly mixed composite foaming agent. A secondary ball milling process further ensures uniform mixing of the composite foaming agent with solid waste, effectively preventing excessive bubble growth and improving the uniformity and dispersibility of the sample's pore structure, thereby enhancing the mechanical properties of the porous glass ceramics. Furthermore, the process requires only simple ball milling followed by a single sintering step, with melting, foaming, and sintering occurring simultaneously, simplifying the process. Results from the embodiments show that the compressive strength of the porous glass ceramics prepared by this invention exceeds 7.21 MPa, higher than that of a single foaming agent and a composite foaming agent composed of sodium carbonate and silicon carbide. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the mold structure used in the preparation of solid waste-based porous glass ceramics according to the present invention, wherein 1 is the composite layer, 2 is the filling layer, and 3 is the inner layer; Figure 2 The XRD patterns of granite powder 1, waste glass powder 1, and the prepared solid waste-based porous glass ceramics used in Example 1 of this invention are shown. Figure 3 A photograph of the solid waste-based porous glass ceramic prepared in Example 1 of this invention; Figure 4 The image shows the solid waste-based porous glass ceramic prepared in Example 1 of this invention under a high-power electron microscope with a scale bar of 500 μm. Figure 5 This is a 200x SEM image of the solid waste-based porous glass ceramic prepared in Example 1 of the present invention. Figure 6 The XRD patterns of granite powder 1 and the prepared solid waste-based porous glass ceramics used in Example 16 of this invention are shown. Figure 7 The XRD patterns are of the coal gangue powder, waste glass powder 1, and the prepared solid waste-based porous glass ceramics used in Example 18 of the present invention. Figure 8 This is a photograph of the solid waste-based porous glass ceramic prepared in Example 18 of the present invention. Figure 9The image shows the solid waste-based porous glass ceramic prepared in Example 18 of this invention under a high-power electron microscope with a scale bar of 500 μm. Figure 10 This is a SEM image of the solid waste-based porous glass ceramic prepared in Example 18 of the present invention, magnified 200 times. Detailed Implementation

[0019] This invention provides a method for preparing solid waste-based porous glass ceramics, comprising the following steps: (1) Mix foaming agent A and foaming agent B and ball mill once to obtain a composite foaming agent; foaming agent A includes one or more of manganese dioxide, titanium dioxide, ferric oxide and copper oxide; foaming agent B includes one or more of silicon carbide, silicon nitride, boron nitride, titanium carbide and titanium nitride; (2) The composite foaming agent obtained in step (1) is mixed with solid waste and then sintered after secondary ball milling to obtain solid waste-based porous glass ceramic.

[0020] Unless otherwise specified, the present invention does not impose any special restrictions on the source of the raw materials, and commercially available products well known to those skilled in the art can be used.

[0021] This invention involves mixing foaming agent A and foaming agent B and then ball milling them once to obtain a composite foaming agent.

[0022] In this invention, the foaming agent A comprises one or more of manganese dioxide, titanium dioxide, ferric oxide, and copper oxide; the foaming agent B comprises one or more of silicon carbide, silicon nitride, boron nitride, titanium carbide, and titanium nitride. In this invention, the composite foaming agent is preferably a mixture of manganese dioxide and silicon carbide, a mixture of titanium dioxide and boron nitride, a mixture of copper oxide and silicon carbide, or a mixture of manganese dioxide and boron nitride.

[0023] In this invention, the foaming agent A mainly undergoes a high-temperature deoxidation reaction, while the foaming agent B mainly undergoes a high-temperature oxidation reaction. The oxygen generated by the high-temperature deoxidation reaction of the foaming agent A supplies the oxygen consumed by the oxidation reaction of the foaming agent B. At the same time, the excess gas can also form bubbles in the high-temperature glass melt, thereby increasing the porosity of the porous glass ceramic.

[0024] In this invention, the high-temperature deoxidation reaction of the foaming agent A is as follows: 4XO2 2X2O3+O2↑ 6X2O3 4X3O4+O2↑ Where X is Mn, Ti, Fe or Cu.

[0025] In this invention, the high-temperature oxidation reaction of the foaming agent B is as follows: YN+2O2 YO2 + NO2↑ 2YN+3O2 2YO2 + 2NO↑ YC+2O2 YO2 + CO2↑ 2YC+3O2 2YO2 + 2CO↑ Where Y is Si, Ti, or B.

[0026] In this invention, the preferred mass ratio of foaming agent A to foaming agent B is (0.1~10):1, more preferably (1~5):1, and most preferably (1~2):1. By limiting the mass ratio of foaming agent A to foaming agent B within the above range, this invention ensures sufficient oxygen supply for the oxidation reaction of foaming agent B, while excess gas forms bubbles in the high-temperature glass melt, thereby increasing the porosity of the porous glass ceramic.

[0027] In this invention, the ball-to-material ratio of the first ball milling is preferably (10~30):1, more preferably (15~25):1, and most preferably 20:1; the ball milling time is preferably 1~3 hours, more preferably 2 hours. In this invention, the ball milling enables the two different foaming agents to be mixed evenly, and also reduces the particle size of the foaming agent to a certain extent, increasing its specific surface area and giving it more active sites, thereby achieving activation and contributing to obtaining porous glass-ceramics with relatively smaller pore sizes.

[0028] After one ball milling, the product of the ball milling is preferably passed through an 80-120 mesh sieve to obtain a composite foaming agent.

[0029] This invention limits the ball-to-material ratio, time, and mesh size of the composite foaming agent after ball milling to the above-mentioned range, which enables foaming agent A and foaming agent B to be mixed more uniformly, while having a smaller particle size, reducing the pore size of porous glass ceramics, and improving their mechanical properties.

[0030] After obtaining the composite foaming agent, the present invention mixes the composite foaming agent with solid waste, performs secondary ball milling, and then sintersulates to obtain solid waste-based porous glass ceramics.

[0031] In this invention, the solid waste preferably includes one or more of granite cutting slag and coal gangue. In this invention, the mass content of silicon dioxide and aluminum oxide in the granite cutting slag and coal gangue is preferably ≥80% independently, and the mass content of ferric oxide is preferably ≥1.5% independently.

[0032] In this invention, the solid waste preferably includes waste glass.

[0033] In this invention, the mass content of silicon dioxide and aluminum oxide in the waste glass is preferably ≥68%.

[0034] In this invention, the mass content of waste glass in the solid waste is preferably 0.1-5%, more preferably 1-5%. In this invention, the waste glass contains a high proportion of fluxing agent, which can lower the sintering temperature, avoid the use of conventional fluxing agents (potassium feldspar, sodium feldspar, etc.), and simplify the formulation. Simultaneously, the waste glass forms a glassy liquid phase under high-temperature conditions, which can improve the mechanical strength of porous glass ceramics. Furthermore, the in-situ presence of ferric oxide in the solid waste acts as a nucleation agent, inducing a crystallization reaction in some of the glassy phases formed by the waste glass under high-temperature conditions, thereby improving the utilization rate of solid waste. By limiting the mass content of waste glass in the solid waste to the above range, this invention can further reduce the sintering temperature, improve the utilization rate of solid waste, and enhance the mechanical properties of porous glass ceramics.

[0035] In this invention, the mass of the composite foaming agent is preferably 0.25-3% of the solid waste material, more preferably 0.5-2%, and most preferably 1%. By limiting the amount of the composite foaming agent within the above range, this invention enables porous glass ceramics to have higher porosity and higher mechanical properties.

[0036] In this invention, the ball-to-material ratio of the secondary ball milling is preferably (2~4):1, more preferably 3:1; the secondary ball milling time is preferably 1~5h, more preferably 2~4h.

[0037] After the secondary ball milling is completed, the product of the secondary ball milling is preferably passed through an 80-120 mesh sieve.

[0038] This invention limits the ball-to-material ratio, time, and product mesh size during secondary ball milling to the above-mentioned range, which enables the composite foaming agent to be mixed more evenly with solid waste, while having a smaller particle size, reducing the pore size of porous glass ceramics, and improving their mechanical properties.

[0039] In this invention, when the solid waste contains waste glass, the sintering temperature is preferably 1050~1200℃, more preferably 1100~1200℃; the sintering time is preferably 60~180min, more preferably 120~180min; and the rate of heating to the sintering temperature is preferably 3~10℃ / min, more preferably 5℃ / min. By limiting the sintering temperature and time to the above ranges, this invention enables the components in the raw materials to react fully and form porous glass-ceramics.

[0040] In this invention, the sintering is preferably carried out in a mold, and the structure of the mold is preferably as follows: Figure 1As shown, the mold has a three-layer structure, consisting of a composite layer 1, a filling layer 2, and an inner layer 3 from the outside in; the layers are bonded together with an adhesive.

[0041] In this invention, the adhesive preferably includes one or more of the following: polyvinyl alcohol aqueous solution, polyethylene glycol aqueous solution, xanthan gum aqueous solution, sodium carboxymethyl cellulose aqueous solution, polyvinylpyrrolidone aqueous solution, and chitosan aqueous solution, and the mass concentration of the adhesive is preferably 0.25~1%.

[0042] In this invention, the composite layer 1 and the inner layer 3 are preferably polycrystalline aluminosilicate fiber paper; the filling layer 2 is preferably filled with alumina ceramic balls or zirconia ceramic balls with a diameter of 1.5~3.2mm.

[0043] In this invention, the composite layer 1 provides the mold with a certain mechanical strength, reducing deformation and damage, and the pores formed by the ceramic balls in the filling layer 2 provide a new path for gas diffusion and exchange.

[0044] In this invention, the thickness of the composite layer 1 is preferably 2-6 mm; the thickness of the inner layer 3 is preferably half the thickness of the composite layer 1; and the thickness of the filler layer 2 is preferably 3-9.6 mm. This invention does not impose any special limitations on the size and shape of the mold; it can be selected according to actual needs.

[0045] This invention limits the structure of the mold and the thickness of each layer within the above-mentioned range. The inner layer 3 directly contacts the reactant, and its thinner thickness is conducive to gas diffusion. The outermost layer is the composite layer 1, and its thicker structure ensures that the mold still has a certain mechanical strength after loading, maintaining the integrity of the mold during transportation and high-temperature reaction, which helps to obtain porous glass ceramics with relatively uniform dimensions. The pores formed by the ceramic balls in the filling layer 2 provide a new path for gas diffusion and exchange. Compared with traditional dense and rigid molds such as alumina, mullite, and cordierite, this invention helps to improve the uniformity of the pores in porous glass ceramics.

[0046] After sintering, the present invention preferably cools the sintered product to obtain solid waste-based porous glass ceramics.

[0047] In this invention, the cooling is preferably natural cooling; the endpoint of the cooling is preferably room temperature.

[0048] This invention provides a solid waste-based porous glass ceramic prepared by the preparation method described in the above technical solution.

[0049] The solid waste-based porous glass-ceramic prepared by this invention has smaller and more uniform pore size and excellent mechanical properties.

[0050] The present invention also provides the application of the solid waste-based porous glass ceramics described in the above technical solution in the fields of thermal, chemical, biological, optical and electrical engineering.

[0051] The present invention does not impose any special limitations on the operation of the application of the solid waste-based porous glass ceramic in the fields of thermal, chemical, biological, optical and electrical engineering. Any technical solution known to those skilled in the art for the application of solid waste-based porous glass ceramic in the fields of thermal, chemical, biological, optical and electrical engineering can be used.

[0052] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0053] The composition of the raw materials used in the various embodiments of the present invention and the mass percentage of the main components are shown in Table 1. The raw materials also contain a small amount of other conventional components not listed.

[0054] Table 1 shows the composition of raw materials and the mass percentage of major components used in each embodiment.

[0055] Example 1 (1) MnO2 and SiC with a mass ratio of 1.5:1 were mixed and ball-milled once. The grinding media was zirconia balls and the ball-to-material ratio was 20:1. After ball milling for 2 hours, the mixture was passed through a 100-mesh sieve to obtain a composite foaming agent. (2) The composite foaming agent is mixed with granite powder 1 and waste glass powder 1 and subjected to secondary ball milling. The mass ratio of granite powder 1 to waste glass powder 1 is 95:5, and the mass of the composite foaming agent is 1% of the total mass of granite powder 1 and waste glass powder 1. The grinding medium is zirconia balls, and the ball-to-material ratio is 3:1. After ball milling for 4 hours, the mixture is passed through a 100-mesh sieve, placed into a mold, vibrated, and the upper surface is smoothed. The mold has a three-layer structure, consisting of a composite layer 1, a filling layer 2, and an inner layer 3 from the outside to the inside. Each layer is bonded with a 0.5wt% sodium carboxymethyl cellulose aqueous solution as a binder. The composite layer 1 is polycrystalline aluminosilicate fiber paper with a thickness of 6mm, the inner layer 3 is polycrystalline aluminosilicate fiber paper with a thickness of 3mm, and the filling layer 2 is filled with zirconia ceramic balls with a diameter of 1.5mm and a thickness of 3mm. Finally, the mold containing the powder is placed in a muffle furnace and heated to 1100℃ at a heating rate of 5℃ / min and held at that temperature for 120℃. After being naturally cooled to room temperature, granite solid waste-based porous glass ceramics were obtained.

[0056] The XRD patterns of granite powder 1, waste glass powder 1, and the prepared solid waste-based porous glass ceramic in Example 1 are shown below. Figure 2 As shown, the places with overlapping peaks are not marked repeatedly.

[0057] A physical image of the solid waste-based porous glass-ceramic prepared in Example 1 is shown below. Figure 3 As shown in the image, the scale bar is 500 μm, obtained using a high-powered electron microscope. Figure 4 As shown, the SEM image at 200x magnification is as follows: Figure 5 As shown.

[0058] from Figures 2-5 As can be seen from the data, the main crystalline phases of the porous glass ceramic based on granite solid waste are albite phase and α-quartz phase, and it also contains a certain proportion of orthoclase phase and amorphous glass phase. The interior of the glass ceramic consists of a large number of large pores and abundant small pores on the pore walls and pore ribs. The pore size of these large pores is relatively uniformly distributed, about 100~1000μm, while the pore size of the small pores is unevenly distributed, about 10~100μm. Their cross-sections are mostly regular circular pores and they are all closed and independent, which can improve the thermal insulation performance of porous glass ceramic materials.

[0059] Example 2 In Example 1, granite powder 1 was replaced with granite powder 2, and waste glass powder 1 was replaced with waste glass powder 2. All other parameters were the same as in Example 1.

[0060] Example 3 Replace waste glass powder 1 in Example 1 with waste glass powder 2, and keep all other parameters the same as in Example 1.

[0061] Example 4 In Example 1, granite powder 1 was replaced with granite powder 2, and all other parameters were the same as in Example 1.

[0062] Example 5 The sintering temperature in Example 1 was replaced with 1050℃, and all other parameters were the same as in Example 1.

[0063] Example 6 The sintering temperature in Example 1 was replaced with 1075℃, and all other parameters were the same as in Example 1.

[0064] Example 7 The sintering temperature in Example 1 was replaced with 1125℃, and all other parameters were the same as in Example 1.

[0065] Example 8 The sintering temperature in Example 1 was replaced with 1150℃, and all other parameters were the same as in Example 1.

[0066] Example 9 The sintering temperature in Example 1 was replaced with 1175℃, and all other parameters were the same as in Example 1.

[0067] Example 10 The sintering temperature in Example 1 was replaced with 1200℃, and all other parameters were the same as in Example 1.

[0068] Example 11 The sintering time in Example 1 was replaced with 60 min, and all other parameters were the same as in Example 1.

[0069] Example 12 The sintering time in Example 1 was replaced with 180 min, and all other parameters were the same as in Example 1.

[0070] Example 13 The composite foaming agent in Example 1 was replaced with TiO2 and BN in a mass ratio of 1.5:1, and all other parameters were the same as in Example 1.

[0071] Example 14 The composite foaming agent in Example 1 was replaced with CuO and SiC in a mass ratio of 1.5:1, and all other parameters were the same as in Example 1.

[0072] Example 15 The composite foaming agent in Example 1 was replaced with MnO2 and BN in a mass ratio of 1.5:1, and all other parameters were the same as in Example 1.

[0073] Example 16 (1) MnO2 and SiC with a mass ratio of 1.5:1 were mixed and ball-milled once. The grinding media was zirconia balls and the ball-to-material ratio was 20:1. After ball milling for 2 hours, the mixture was passed through a 100-mesh sieve to obtain a composite foaming agent. (2) The composite foaming agent is mixed with granite powder 1 and ball milled twice. The mass of the composite foaming agent is 1% of the mass of granite powder 1. The grinding medium is zirconia balls and the ball-to-material ratio is 3:1. After ball milling for 4 hours, the mixture is passed through a 100-mesh sieve, placed into a mold, vibrated and smoothed. The mold has a three-layer structure, from the outside to the inside: composite layer 1, filling layer 2 and inner layer 3. Each layer is bonded with 0.5wt% sodium carboxymethyl cellulose aqueous solution as a binder. Composite layer 1 is polycrystalline aluminosilicate fiber paper with a thickness of 6mm. Inner layer 3 is polycrystalline aluminosilicate fiber paper with a thickness of 3mm. Filling layer 2 is filled with zirconia ceramic balls with a diameter of 1.5mm and a thickness of 3mm. Finally, the mold containing the powder is placed in a muffle furnace and heated to 1200℃ at a heating rate of 5℃ / min and held for 120min. After naturally cooling to room temperature, the granite solid waste-based porous glass ceramic is obtained.

[0074] The XRD patterns of granite powder 1 and the prepared solid waste-based porous glass ceramic in Example 16 are shown below. Figure 6 As shown. From Figure 6As can be seen, the main crystalline phases of the solid waste-based porous glass ceramics are α-quartz and albite, while a small amount of orthoclase phase and a certain proportion of amorphous glass phase also exist.

[0075] Example 17 In Example 16, granite powder 1 was replaced with granite powder 2, and all other parameters were the same as in Example 16.

[0076] Example 18 In Example 1, granite powder 1 was replaced with coal gangue powder, and all other parameters were the same as in Example 1, resulting in porous glass ceramics based on coal gangue solid waste.

[0077] The XRD patterns of coal gangue powder, waste glass powder 1, and the prepared solid waste-based porous glass ceramics in Example 18 are shown below. Figure 7 As shown.

[0078] A physical image of the solid waste-based porous glass-ceramic prepared in Example 18 is shown below. Figure 8 As shown in the image, the scale bar is 500 μm, obtained using a high-powered electron microscope. Figure 9 As shown, the SEM image at 200x magnification is as follows: Figure 10 As shown.

[0079] from Figures 7-10 As can be seen, the main crystalline phases of the porous glass-ceramic based on coal gangue solid waste are α-quartz phase, albite, and iron-aluminum oxides, with a small amount of kaolinite phase and a certain proportion of amorphous glass phase. The interior of the glass-ceramic consists of a large number of large pores and abundant small pores on the pore walls and pore ribs. The pore diameter of these large pores is about 300~2000μm, while the pore diameter of the small pores is unevenly distributed, about 10~200μm. Their cross-sections are mostly irregular elliptical pores, and most of them are closed and independent, which can improve the thermal insulation performance of the porous glass-ceramic material.

[0080] Example 19 Replace waste glass powder 1 in Example 18 with waste glass powder 2, and keep all other parameters the same as in Example 18.

[0081] Example 20 The sintering temperature in Example 18 was replaced with 1050℃, and all other parameters were the same as in Example 18.

[0082] Example 21 The sintering temperature in Example 18 was replaced with 1150°C, and all other parameters were the same as in Example 18.

[0083] Example 22 The sintering temperature in Example 18 was replaced with 1200℃, and all other parameters were the same as in Example 18.

[0084] Example 23 The sintering time in Example 18 was replaced with 60 min, and all other parameters were the same as in Example 18.

[0085] Example 24 The sintering time in Example 18 was replaced with 180 min, and all other parameters were the same as in Example 18.

[0086] Example 25 The composite foaming agent in Example 18 was replaced with TiO2 and BN in a mass ratio of 1.5:1, and all other parameters were the same as in Example 18.

[0087] Example 26 The composite foaming agent in Example 18 was replaced with CuO and SiC in a mass ratio of 1.5:1, and all other parameters were the same as in Example 18.

[0088] Example 27 (1) MnO2 and SiC with a mass ratio of 1.5:1 were mixed and ball-milled once. The grinding media was zirconia balls and the ball-to-material ratio was 20:1. After ball milling for 2 hours, the mixture was passed through a 100-mesh sieve to obtain a composite foaming agent. (2) The composite foaming agent and coal gangue powder are mixed and ball-milled twice. The mass of the composite foaming agent is 1% of the mass of the coal gangue powder. The grinding medium is zirconia balls with a ball-to-material ratio of 3:1. After ball milling for 4 hours, the mixture is passed through a 100-mesh sieve, placed in a mold, vibrated and smoothed. The mold has a three-layer structure, from the outside to the inside: composite layer 1, filling layer 2 and inner layer 3. Each layer is bonded with 0.5wt% sodium carboxymethyl cellulose aqueous solution as a binder. Composite layer 1 is polycrystalline aluminosilicate fiber paper with a thickness of 6mm. Inner layer 3 is polycrystalline aluminosilicate fiber paper with a thickness of 3mm. Filling layer 2 is filled with zirconia ceramic balls with a diameter of 1.5mm and a thickness of 3mm. Finally, the mold containing the powder is placed in a muffle furnace and heated to 1200℃ at a heating rate of 5℃ / min. The temperature is held for 120min. After natural cooling to room temperature, the porous glass ceramic based on coal gangue solid waste is obtained.

[0089] Comparative Example 1 (1) MnO2 was ball-milled once, with zirconia balls as the grinding medium and a ball-to-material ratio of 20:1. After ball milling for 2 hours, the mixture was passed through a 100-mesh sieve to obtain a foaming agent. (2) The foaming agent is mixed with granite powder 1 and waste glass powder 1 and subjected to secondary ball milling. The mass ratio of granite powder 1 to waste glass powder 1 is 95:5, and the mass of the foaming agent is 1% of the total mass of granite powder 1 and waste glass powder 1. The grinding medium is zirconia balls, and the ball-to-material ratio is 3:1. After ball milling for 4 hours, the mixture is passed through a 100-mesh sieve, placed into a mold, vibrated, and the upper surface is smoothed. The mold has a three-layer structure, consisting of a composite layer 1, a filling layer 2, and an inner layer 3 from the outside to the inside. Each layer is bonded with a 0.5wt% sodium carboxymethyl cellulose aqueous solution as a binder. The composite layer 1 is polycrystalline aluminosilicate fiber paper with a thickness of 6mm, the inner layer 3 is polycrystalline aluminosilicate fiber paper with a thickness of 3mm, and the filling layer 2 is filled with zirconia ceramic balls with a diameter of 1.5mm and a thickness of 3mm. Finally, the mold containing the powder is placed in a muffle furnace and heated to 1100℃ at a heating rate of 5℃ / min and held at that temperature for 120℃. After being naturally cooled to room temperature, granite solid waste-based porous glass ceramics were obtained.

[0090] Comparative Example 2 The foaming agent in Comparative Example 1 was replaced with SiC, and all other parameters were the same as in Comparative Example 1.

[0091] Comparative Example 3 The composite foaming agent in Comparative Example 1 was replaced with Na2CO3 and SiC in a mass ratio of 1.5:1, while all other parameters remained the same as in Comparative Example 1.

[0092] The solid waste-based porous glass ceramics prepared in Examples 1-27 and Comparative Examples 1-3 were characterized in accordance with GB / T5486-2008, GB / T1964-1996, and GB / T1966-1996. Their apparent density, porosity, thermal conductivity, and compressive strength are shown in Table 2.

[0093] Table 2 shows the apparent density, porosity, thermal conductivity, and compressive strength of the solid waste-based porous glass ceramics prepared in Examples 1-27 and Comparative Examples 1-3.

[0094] As can be seen from Table 2, the solid waste-based porous glass ceramic prepared by this invention has high compressive strength.

[0095] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. Other embodiments can be obtained based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method for preparing a solid waste-based porous glass ceramic, comprising the following steps: (1) Foaming agent A and foaming agent B are mixed and ball-milled once to obtain a composite foaming agent; foaming agent A includes one or more of manganese dioxide, titanium dioxide, ferric oxide and copper oxide; foaming agent B includes one or more of silicon carbide, silicon nitride, boron nitride, titanium carbide and titanium nitride; the mass ratio of foaming agent A to foaming agent B is (0.1~10):1; (2) The composite foaming agent obtained in step (1) is mixed with solid waste and then ball-milled twice. The mixture is then placed in a mold for sintering to obtain solid waste-based porous glass ceramics. The mold has a three-layer structure, consisting of a composite layer (1), a filling layer (2), and an inner layer (3) from the outside in. The composite layer (1) and the inner layer (3) are made of polycrystalline aluminosilicate fiber paper. The filling layer (2) is filled with alumina ceramic balls or zirconia ceramic balls with a diameter of 1.5~3.2mm. The thickness of the inner layer (3) is half the thickness of the composite layer (1). The pores in the solid waste-based porous glass ceramic are closed-cell structures.

2. The preparation method according to claim 1, characterized in that, In step (2), the mass of the composite foaming agent is 0.25-3% of the solid waste mass.

3. The preparation method according to claim 1, characterized in that, The solid waste in step (2) includes one or more of granite cutting slag and coal gangue.

4. The preparation method according to claim 3, characterized in that, The mass content of silicon dioxide and aluminum oxide in the granite cutting slag and coal gangue is independently ≥80%, and the mass content of ferric oxide is independently ≥1.5%.

5. The preparation method according to claim 3, characterized in that, The solid waste includes waste glass.

6. The preparation method according to claim 5, characterized in that, The waste glass content in the solid waste is 0.1% to 5% by mass.

7. The preparation method according to claim 1, characterized in that, The ball-to-material ratio for the first ball milling is (10~30):1; The ball-to-material ratio for the secondary ball milling is (2~4):

1.

8. The preparation method according to claim 5 or 6, characterized in that, The sintering temperature in step (2) is 1050~1200℃ and the sintering time is 60~180min.

9. Solid waste-based porous glass ceramics prepared by the preparation method according to any one of claims 1 to 8.

10. The application of the solid waste-based porous glass ceramic of claim 9 in the fields of thermal, chemical, biological, optical and electrical engineering.

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