CN115108726A - Porous glass ceramics taking coal gangue as raw material and preparation method thereof - Google Patents

Abstract

The invention provides a porous glass-ceramic using coal gangue as a raw material and a preparation method thereof. The method comprises the following steps: uniformly mixing coal gangue powder and asbestos tailing powder, or mixing the coal gangue powder with The porous agent is evenly mixed to obtain the preform powder; the obtained preform powder and the binder are mixed evenly, granulated and dried to obtain the preform pellet; the preform pellet is molded to obtain the porous glass-ceramic raw material. Green body; heat treatment and cooling of the green body of the porous glass-ceramic to obtain the porous glass-ceramic. The porous glass-ceramic includes the porous glass-ceramic prepared by the above method. The beneficial effects of the invention include: rationally and effectively comprehensively utilizing coal gangue and asbestos tailings, and realizing the maximum utilization of solid waste resources.

Description

Porous glass-ceramic using coal gangue as raw material and preparation method thereof

technical field

The invention relates to the fields of solid waste treatment and resource utilization and inorganic non-metallic functional materials, in particular, to a porous glass-ceramic using coal gangue as a raw material and a preparation method thereof.

Background technique

Coal gangue is a solid waste discharged during the process of excavation, mining and coal washing. With the extensive mining and utilization of coal, the piled up of coal gangue has also increased sharply. At present, based on the concept of "turning waste into treasure", the high-temperature melting method is mostly used to prepare glass-ceramics from coal gangue, so that the powder or pellets have strong particle bonding, gradually densified and crystallized, so as to obtain a high-energy state. The glass body is widely used in ceramic tiles, wall composite panels and other building decoration materials or refractory raw materials. Using coal gangue as raw material to prepare glass-ceramics realizes the utilization of solid waste resources, which has certain reference significance for the environment and the material industry.

The invention patent with the publication number CN108503224A discloses a glass-ceramic with coal gangue and rice husk ash as the main raw materials and a preparation method thereof. The invention uses coal gangue and rice husk ash as main raw materials, and additionally adds auxiliary materials such as cosolvent Na ₂ CO ₃ , nucleating agent Ti ₂ O ₃ , CaCO ₃ , MgO and the like. Then, after the powder is melted at about 1450°C, water quenching-grinding-molding-sintering is performed in sequence, and the obtained glass-ceramic is dense, and the main phases are anorthite and diopside. The invention patent with the publication number CN105924012A discloses a method of using coal gangue as a raw material, using an all-electric melting rolling method, and sequentially performing high-temperature melting powder - rolling forming - annealing - cutting - nucleation - crystallization - annealing treatment to obtain blue colored glass-ceramic plates. The invention patent with publication number CN109553304A discloses a slag porous glass-ceramic. In the invention, the basic glass powder is used as the raw material, and the binder and the pore-forming agent are mixed uniformly according to a certain ratio, and then molded, and then sintered twice to form primary and secondary pores respectively, so as to obtain light weight and good heat insulation effect. of porous glass-ceramic.

The above invention has problems such as high melting temperature, high energy consumption, cumbersome preparation process, long period or the need to add additional pore-forming agent.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art, and one of the purposes of the present invention is to provide a reasonable and effective comprehensive utilization of coal gangue and asbestos tailings to maximize the utilization of solid waste resources Methods.

In order to achieve the above object, one aspect of the present invention provides a method for preparing porous glass-ceramic from coal gangue.

The method includes the following steps: uniformly mixing coal gangue powder and asbestos tailing powder, or uniformly mixing coal gangue powder and pore-forming agent to obtain billet powder; making the obtained billet powder and bonding The preforms are mixed uniformly, granulated and dried to obtain preform pellets; the preform pellets are molded to obtain a porous glass-ceramic green body; the porous glass-ceramic green body is heat-treated and cooled to obtain a porous glass-ceramic ; Among them, coal gangue powder and asbestos tailings powder are obtained by pretreatment of coal gangue and asbestos tailings respectively.

According to an exemplary embodiment of the present invention, the ratio of the mass percentage of the coal gangue powder to the asbestos tailings powder may be 70-90%: 10-30%. In other words, based on the sum of the mass fractions of coal gangue powder and asbestos tailings powder as 100 parts, the mass fraction of coal gangue powder can be 70-90 parts, such as 71 parts, 75 parts, 80 parts. , 85 parts, 89 parts, etc., and the balance is asbestos tailings powder.

According to an exemplary embodiment of the present invention, the mineral phases of the coal gangue may include quartz and kaolin; the loss on ignition of the coal gangue may be 11.34-23.48%; the coal gangue may include mass percent The following components: 20.21%-68.16% SiO ₂ , 7.3%-50.41% Al ₂ O ₃ , 7.24%-20.58% Fe ₂ O ₃ , 3.41%-7.18% CaO, 0.66%-4.42% TiO ₂ .

According to an exemplary embodiment of the present invention, the mineral phases of the asbestos tailings may include serpentine and brucite; the loss on ignition of the asbestos tailings may be 6.38-16.31%; the asbestos tailings may be It includes the following components by mass percentage: 20.14%-60.42% MgO, 15.68%-55.32% SiO ₂ , 5.19%-30.58% Fe ₂ O ₃ , 2.16%-10.24% CaO.

According to an exemplary embodiment of the present invention, the pretreatment may include roasting, grinding and homogenization; wherein, the roasting temperature of coal gangue may be 750-800° C., the roasting temperature of asbestos tailings may be 850-900° C. The time can be 30～60min, the heating rate can be controlled at 5～8°C/min; the heating time can be controlled at 100～180min; the particle size of the blank powder can be 0.025～0.070mm.

According to an exemplary embodiment of the present invention, the binder may include 5-8wt% polyvinyl alcohol solution; the weight ratio of the binder to the preform powder may be 5-10:90～ 95; the particle size of the blank-making pellets may be 0.22mm-0.86mm; the moisture content of the blank-making pellets may be 4%-6%; the pressure for molding the blank-making pellets may be 20-50MPa , the pressure is maintained for 10 to 40s.

According to an exemplary embodiment of the present invention, the pore-forming agent may include one or more of a polyurethane foam pore-forming agent, silicon carbide, borax and calcium carbonate.

According to an exemplary embodiment of the present invention, the heat treatment may include two-stage continuous sintering; wherein, the heating rate in the first stage is controlled to be 5-8°C/min, and the temperature is gradually heated from room temperature to 900-1000°C; the second stage is controlled The heating rate is 2-5°C/min, and the temperature is continued from 900-1000°C to 1100°C-1200°C; the temperature is maintained for 10-60 minutes, and then naturally cooled to room temperature.

On the other hand, the present invention provides a porous glass-ceramic with coal gangue as a raw material. The porous glass-ceramic may include the porous glass-ceramic prepared by the above-mentioned method for preparing porous glass-ceramic from coal gangue.

According to an exemplary embodiment of the present invention, the phase of the porous glass-ceramic may include cordierite, mullite and iron spinel; the linear expansion of the porous glass-ceramic is 9.41-10.22%, and the porosity is 9.41-10.22%. 42.13-73.25%, the bulk density is 1.29-1.37g/cm ³ , and the water absorption rate is 0.35-0.44%.

Compared with the prior art, the beneficial effects of the present invention include at least one of the following:

(1) Reasonable and effective comprehensive utilization of coal gangue and asbestos tailings, maximizing the utilization of solid waste resources, skillfully exerting the pore-forming effect of comprehensive utilization of coal gangue and asbestos tailings, and realizing solid waste maximum resource utilization.

(2) The active ingredients react synergistically to obtain high value-added porous glass-ceramics.

(3) Zero addition of sintering aids and foaming agents can save the cost of raw materials.

(4) The preparation process is simple; the porous glass-ceramic has excellent performance: high porosity, light weight, high strength, large specific surface area and good air permeability, suitable for catalyst carrier, external wall insulation, sound absorption and noise reduction, waste gas filtration and wastewater treatment and many other fields.

(5) The high energy consumption process of high-temperature melting to obtain a high-energy state glass body in the traditional glass-ceramic preparation process is omitted, the sintering temperature is low, the process is simple, and the energy consumption is low.

Description of drawings

The above and other objects and features of the present invention will become more apparent from the following description in conjunction with the accompanying drawings, wherein:

1 shows a flow chart of a method for preparing porous glass-ceramic from coal gangue according to an exemplary embodiment of the present invention;

FIG. 2 shows a surface view of a porous glass-ceramic sample using coal gangue as a raw material according to an exemplary embodiment of the present invention;

3 shows a cross-sectional view of a porous glass-ceramic sample using coal gangue as a raw material according to an exemplary embodiment of the present invention;

FIG. 4 shows an X-ray diffraction pattern of a porous glass-ceramic sample using coal gangue as a raw material according to an exemplary embodiment of the present invention.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention.

Exemplary Embodiment 1

At present, the technology of preparing glass-ceramics from solid waste has become mature. However, there are few technologies that can directly utilize the synergy between solid wastes or the high-temperature phase reconstruction process to form pores without adding additional pore-forming agents or foaming agents. Any chemical reagent to prepare porous glass-ceramic technology.

Coal gangue is a coal-based industrial solid waste produced along with coal mining and washing and processing, accounting for about 1/4 of the national industrial waste discharge. At present, most of the resource utilization of coal gangue is mainly based on rough processing, with low added value. There is an urgent need for a resource utilization method with high added value of coal gangue. Therefore, the present invention proposes a method for preparing porous glass-ceramic by using coal gangue as a raw material. The method uses coal gangue as the main raw material, adds an appropriate amount of roasted asbestos tailings, and adopts direct sintering to prepare porous glass-ceramics. , Porous glass-ceramic has high added value.

The preparation of the porous glass-ceramic of the present invention takes coal gangue or roasted coal gangue and asbestos tailings as main raw materials, and adopts a direct sintering method to prepare the preparation process with low energy consumption and simple flow.

The present exemplary embodiment provides a method for preparing porous glass-ceramic from coal gangue. The method specifically includes the following steps:

S1. The coal gangue and the asbestos tailings are separately pretreated and mixed evenly to obtain a billet powder.

In this embodiment, the ratio of the mass percentage of coal gangue to asbestos tailings may be 70-90%: 10-30%; for example, 70%: 30%, 89%: 11%, 90%: 10%. That is, the mass ratio of coal gangue and asbestos tailings is 70-90:10-30.

It should be noted that the quality of the material before and after pretreatment changes very little. It can be considered that the mass ratio of coal gangue powder and asbestos tailing powder in the billet powder is 70-90:10-30.

In this embodiment, the mineral phases of coal gangue may include quartz and kaolin. Coal gangue contains carbon or crystal water. In order to make the green body not easily deformed during the sintering process and the shrinkage of the sintered sample is small, the coal gangue needs to be roasted in advance. , 12%, 15%, 17%, 19%, 21%, 22%, 23.3%.

In this embodiment, the coal gangue may include the following components by mass percentage:

20.21%～68.16% SiO ₂ , such as 24.24%, 28.14%, 30.53%, 35.33%, 40.51%, 50.77%;

7.3%～50.41%Al ₂ O ₃ , such as 8.18%, 10.58%, 20.93%, 35.16%, 40.18%, 43.86%;

7.24%～20.58% Fe ₂ O ₃ , such as 8.78%, 8.95%, 9.1%, 9.24%, 10.56%, 11.48%, 15.14%, 19.58%;

3.41%～7.18%CaO, such as 3.47%, 5.23%, 6.14%, 6.32%, 7.15%;

0.66% to 4.42% _TiO2 , such as 2.87%, 2.91%, 3.42%, 4.16%, 4.35%.

In this embodiment, the mineral phases of the asbestos tailings may include serpentine and brucite. Asbestos tailings contain a small amount of asbestos or crystal water. In order to make the china difficult to deform during the sintering process and the shrinkage rate of the sintered samples is small, the asbestos tailings need to be roasted in advance. The loss on ignition of asbestos tailings is 6.38-16.31%. For example 6.5%, 8.5%, 9%, 9.5%, 10%, 11%, 12%, 13%, 15%, 16%.

The asbestos tailings may include the following components in percent by mass:

20.14%～60.42%MgO, such as 22.16%, 27.87%, 31.42%, 36.89%, 45.72%, 50.43%;

15.68%～55.32% SiO ₂ , such as 17.43%, 23.42%, 35.89%, 39.65%, 46.16%, 50.21%;

5.19%～30.58% Fe ₂ O ₃ , such as 7.46%, 13.66%, 19.29%, 22.62%, 15.62%, 28.14%;

2.16% to 10.24% CaO, such as 3.57%, 4.82%, 6.05%, 7.42%, 8.14%, 9.01%.

In this embodiment, the pretreatment may include firing, grinding, and homogenization.

Among them, roasting includes completing roasting of raw materials in a box furnace. In order to prevent the high temperature furnace from being heated too fast, the heating rate is controlled at 5-8°C/min, such as 5.5°C/min, 6°C/min, 7°C/min, 7.5°C/min. The heating time is controlled at 100-180min, such as 110min, 120min, 130min, 140min, 150min, 170min; and then kept for 30-60min, such as 35min, 40min, 45min, 50min, 55min. The roasting temperature of coal gangue is gradually raised from room temperature to 750-800 °C, such as 760 °C, 770 °C, 780 °C, 790 °C, to remove excess carbon in the coal gangue, and the roasted coal gangue is light pink in color. The roasting temperature of asbestos tailings is gradually raised from room temperature to 850-900°C, such as 860°C, 870°C, 880°C, and 890°C, to remove excess asbestos in asbestos tailings. After the roasting is completed, the furnace cools down and naturally cools, and the roasted powder is ground into 0.025-0.070mm blank powder, such as 0.026mm, 0.030mm, 0.033mm, 0.048mm, 0.055mm, 0.064mm, 0.069mm . The particle size of the blank-making powder is controlled at 0.025-0.070mm, which is not only conducive to uniform granulation and green body molding, but also the sintered samples have uniform pores and good performance. If the particle size of the preformed powder is larger than 0.070mm, the pore distribution in the sintered sample will be uneven, and the glass-ceramic properties, including water absorption and bulk density, will be poor. Homogenization treatment includes sieving. The purpose of homogenization treatment is to make the calcined and ground samples as evenly distributed as possible after sieving, grinding and mixing.

S2, making the obtained blank-making powder and the binder evenly mixed, granulated and dried to obtain blank-making granules.

In this embodiment, the binder is a 5-8 wt% polyvinyl alcohol solution, such as 5.5%, 6%, 7%, and 7.5%. The weight ratio of the binder to the preform powder is 5-10:90-95, such as 5:95, 6:94, 7:93, 8:92, 9:91, 10:90. The polyvinyl alcohol solution has adhesiveness. If its concentration is lower than 5wt%, it will not play the role of adhesion, and the powder is not easy to form pellets, so that it is not easy to make the green body stable; if the concentration is greater than 8wt%, the polyvinyl alcohol solution and The preform powder is bonded into large particles, and it is not easy to form particles with a particle size of 0.22mm to 0.86mm, so that the preform is not easy to be formed or the distribution of pores in the sintered sample is uneven, and the performance of the sintered sample is deteriorated.

In this embodiment, granulation includes sieving granulation.

In this embodiment, the obtained pellets have a particle size of 0.22 mm to 0.86 mm, such as 0.32 mm, 0.38 mm, 0.45 mm, 0.58 mm, and 0.67 mm. The particle size of the blanks is controlled at 0.22mm to 0.86mm, which is not only beneficial to the uniform molding of the blanks, but also to the uniform sintering of the samples and the better performance of the samples after sintering. After being naturally air-dried, the moisture content of the pellets is 4% to 6%, for example, 4.4%, 5.2%, and 5.8%. If the water content of the pellets is high, not only will a large amount of water be squeezed out during the molding process, causing the mold to rust, but also the green body will be difficult to demould, and even the sample will be easily deformed during the sintering process.

S3, molding the green pellets to obtain a green porous glass-ceramic body.

In this embodiment, the preform pellets satisfying the moisture content of 4% to 6% are put into a cylindrical mold, and the preform pellets are molded by using an infrared powder tableting machine. The green body forming pressure can be 20-50 MPa, such as 21 MPa, 23 MPa, 31 MPa, 37 MPa, 40 MPa, 41 MPa, 49 MPa. If the molding pressure is less than 20MPa, the internal pellets of the obtained china are not fully bonded together, and the china is prone to cracks; if the molding pressure is greater than 50MPa, the china is not easy to be demolded, and the mold is easily damaged. In order to make all parts of the green body evenly stressed, the pressure can be maintained for 10 to 40 s, such as 11 s, 15 s, 24 s, 35 s, 38 s, to obtain a cylindrical glass-ceramic green body, which is placed flat for 24 hours.

S4, heat-treating the porous glass-ceramic green body and cooling to obtain the porous glass-ceramic.

In this embodiment, the heat treatment includes placing the green porous glass-ceramic body in a tunnel kiln, and continuously increasing the temperature in two stages. The first stage: set the heating rate to 5～8℃/min, such as 5.5℃/min, 6℃/min, 7℃/min, and the temperature in the kiln is gradually heated from room temperature to 900～1000℃, such as 910℃, 950℃ , 980℃, 990℃. The second stage: set the heating rate to 2～5℃/min, such as 2.5℃/min, 3℃/min, 4℃/min, the temperature in the kiln is gradually raised from 900～1000℃ to 1100～1200℃, for example 1110℃ , 1143℃, 1154℃, 1168℃, etc. The holding time is 10 to 60 minutes, such as 23 minutes, 36 minutes, 41 minutes, 56 minutes, and the like. Naturally cooled to room temperature with the furnace to obtain porous glass-ceramics. Considering the stability of the sintering furnace, below 1000 °C, the heating rate is controlled at 5-8 °C/min; above 1000 °C, in order to make the high-temperature phase reconstruction process of the sample uniform and the crystal formation and formation slow during the high-temperature sintering process of the sample, the temperature rise is controlled. The rate is 2～5℃/min, and the sintering temperature is between 1100℃～1200℃, and the sintered samples are porous.

In this embodiment, FIG. 1 shows a flow chart of a method for preparing porous glass-ceramic by using coal gangue and asbestos tailings.

Exemplary Embodiment 2

This exemplary embodiment provides a method for preparing porous glass-ceramic from coal gangue, which is directly sintered with coal gangue as a raw material to prepare porous glass-ceramic. The method for preparing porous glass-ceramic from coal gangue provided in this exemplary embodiment is generally the same as that in exemplary embodiment 1, except that: this exemplary embodiment uses coal gangue powder and pore-forming agent as raw materials to prepare porous micro-ceramics. Crystal glass, other process control parameters can be the same. Specifically, the method may include the following steps:

S1. Mix the coal gangue powder with the pore-forming agent uniformly to obtain the green body powder.

In this embodiment, the coal gangue is pretreated, including roasting, grinding and homogenization to obtain coal gangue powder.

In this embodiment, the pore-forming agent includes at least one of polyurethane foam pore-forming agent, silicon carbide, borax and calcium carbonate.

In this embodiment, the mass ratio of coal gangue powder to pore-forming agent is 75-85:15-25. In other words, based on the sum of the mass fractions of the coal gangue powder and the pore-forming agent as 100 parts, the mass fraction of the coal gangue powder can be 75-85 parts, such as 76 parts, 78 parts, 80 parts, 82 parts. parts, 84 parts, etc., and the balance is pore-forming agent.

S2, making the obtained blank-making powder and the binder evenly mixed, granulated and dried to obtain blank-making granules.

S3, molding the green pellets to obtain a green porous glass-ceramic body.

S4, heat-treating the porous glass-ceramic green body and cooling to obtain the porous glass-ceramic.

Exemplary Embodiment 3

The present exemplary embodiment provides a porous glass-ceramic using coal gangue as a raw material. The porous glass-ceramic includes the porous glass-ceramic prepared by the method for preparing porous glass-ceramic from coal gangue described in Exemplary Embodiment 1.

In this embodiment, the linear expansion rate of the porous glass-ceramic is 9.41-10.22%, the porosity is 42.13-73.25%, the bulk density is 1.29-1.37 g/cm ³ , and the water absorption rate is 0.35-0.44%. Fig. 2 and Fig. 3 respectively show the surface view and cross-sectional view of the porous glass-ceramic sample of the present invention. It can be seen from Fig. 2 and Fig. 3 that the surface of the porous glass-ceramic sample prepared by the present invention is dense and has good gloss. There are pores in the internal section of the sample, and the porosity increases with the increase of sintering temperature.

In this embodiment, the main phases of the porous glass-ceramics include cordierite, mullite and iron spinel. Figure 4 shows the X-ray diffraction pattern of the porous glass-ceramic sample prepared by the present invention, which reflects the phase change process in the sintered sample under different asbestos tailings addition amounts. In FIG. 4, 1 represents mullite, 2 represents quartz, 3 represents cordierite, and 4 represents iron spinel.

For a better understanding of the exemplary embodiments of the present invention, further descriptions are given below in conjunction with specific examples.

Example 1

The roasting of the raw materials is done in a box furnace. The heating rate was controlled at 6°C/min, the calcination time was controlled at 120 min, and the temperature was kept for 35 min. The roasting temperature of coal gangue is gradually increased from room temperature to 760 ℃, so as to get rid of the excess carbon in the coal gangue, and the color of the roasted coal gangue is light pink. The roasting temperature of asbestos tailings is gradually increased from room temperature to 850 ℃ to remove excess asbestos in asbestos tailings. After the calcination is completed, it is naturally cooled, and the calcined powders are respectively ground into 0.048mm billet powders.

The main phases of coal gangue are kaolin and quartz. The mass percentages of main chemical components are SiO ₂ 50.77%, Al ₂ O ₃ 29.61%, Fe ₂ O ₃ 8.95%, CaO 6.32%, TiO ₂ 4.35%.

The main phases of asbestos tailings are serpentine and brucite. The mass percentages of main chemical components are MgO 50.43%, SiO ₂ 39.65%, Fe ₂ O ₃ 7.66%, CaO 2.26%.

The roasted and ground coal gangue powder and asbestos tailing powder are mixed uniformly according to the formula, and the mass percentage of the coal gangue and asbestos tailing powder is 89%: 11%.

A polyvinyl alcohol solution with a mass fraction of 8 wt % is added to the billet powder as a binder, and the mass ratio of the polyvinyl alcohol solution to the billet powder is 8:92, sieving and granulating, and the obtained billet granules are obtained. The diameter is 0.38mm, and after natural air-drying, the moisture content of the pellets is 5.2%.

The pellets that meet the moisture content requirements are loaded into a cylindrical mold, and the green body molding pressure is 28 MPa. In order to make all parts of the green body uniformly stressed, the pressure is maintained for 25 s to obtain a porous glass-ceramic green body.

The porous glass-ceramic green body is placed in a tunnel kiln and heated continuously in two stages. The first stage: the heating rate is set to 5℃/min, and the temperature in the kiln is gradually heated from room temperature to 900℃. The second stage: set the heating rate to 2°C/min, the temperature in the kiln is gradually raised from 900°C to 1110°C, the holding time is 46min, and the furnace is naturally cooled to room temperature to obtain porous glass-ceramics.

After testing, the main phases of the porous glass-ceramic prepared by the method of Example 1 are cordierite, mullite and iron spinel, the linear expansion rate is 9.45%, the porosity is 56.75%, and the bulk density is 1.32g/cm ³ , the water absorption rate is 0.36%.

Example 2

The roasting of the raw materials is done in a box furnace. The heating rate was controlled at 7°C/min, the calcination time was controlled at 140 min, and the temperature was kept for 50 min. The roasting temperature of coal gangue is gradually increased from room temperature to 750 ℃, so as to get rid of the excess carbon in the coal gangue, and the color of the roasted coal gangue is light pink. The roasting temperature of asbestos tailings is gradually increased from room temperature to 870℃ to remove excess asbestos in asbestos tailings. After the calcination is completed, it is naturally cooled, and the calcined powders are respectively ground into 0.033mm billet powders.

The main phases of coal gangue are kaolin and quartz. The mass percentages of main chemical components are SiO ₂ 65.77%, Al ₂ O ₃ 19.61%, Fe ₂ O ₃ 9.95%, CaO 3.42%, TiO ₂ 1.25%.

The main phases of asbestos tailings are serpentine and brucite. The mass percentages of main chemical components are MgO56.43%, _SiO2 30.65%, _Fe2O3 10.66%, _CaO3.26 %.

The roasted coal gangue powder and asbestos tailing powder are mixed uniformly according to the formula, and the mass percentage of the coal gangue and asbestos tailing powder is 95%:5%.

A polyvinyl alcohol solution with a mass fraction of 5 wt % is added to the billet powder as a binder, and the mass ratio of the polyvinyl alcohol solution to the billet powder is 5:95, sieving and granulating, and the obtained billet granules are obtained. The diameter is 0.45mm, and after natural air drying, the moisture content of the pellets is 4.5%.

The pellets that meet the moisture content requirements are loaded into a cylindrical mold, and the green body molding pressure is 45 MPa. In order to make all parts of the green body uniformly stressed, the pressure is maintained for 20 s to obtain a porous glass-ceramic green body.

The porous glass-ceramic green body is placed in a tunnel kiln and heated continuously in two stages. The first stage: the heating rate is set to 6℃/min, and the temperature in the kiln is gradually heated from room temperature to 950℃. The second stage: set the heating rate to 3°C/min, the temperature in the kiln is gradually raised from 950°C to 1150°C, the holding time is 30min, and naturally cooled to room temperature with the furnace to obtain porous glass-ceramics.

After testing, the main phases of the porous glass-ceramic prepared by the method of Example 2 are cordierite, mullite and iron spinel, the linear expansion rate is 9.56%, the porosity is 66.75%, and the bulk density is 1.34g/cm ³ , the water absorption rate is 0.37%.

Example 3

The roasting of the raw materials is done in a box furnace. The heating rate was controlled at 8°C/min, the calcination time was controlled at 160 min, and the temperature was kept for 40 min. The roasting temperature of coal gangue is gradually increased from room temperature to 780 ℃, so as to get rid of the excess carbon in the coal gangue, and the color of the roasted coal gangue is light pink. The roasting temperature of asbestos tailings is gradually increased from room temperature to 880℃ to remove excess asbestos in asbestos tailings. After the calcination is completed, it is naturally cooled, and the calcined powders are ground into 0.055mm preformed powders respectively.

The main phases of coal gangue are kaolin and quartz. The mass percentages of main chemical components are SiO ₂ 55.77%, Al ₂ O ₃ 25.61%, Fe ₂ O ₃ 10.95%, CaO 4.42%, TiO ₂ 3.25%.

The main phases of asbestos tailings are serpentine and brucite. The mass percentages of the main chemical components are MgO 46.43%, SiO ₂ 40.65%, Fe ₂ O ₃ 8.66%, CaO 4.26%.

The roasted coal gangue and asbestos tailing powder are mixed uniformly according to the formula, and the mass percentage of the coal gangue and asbestos tailing powder is 85%: 15%.

A polyvinyl alcohol solution with a mass fraction of 7wt% was added to the billet powder as a binder, and the mass ratio of the polyvinyl alcohol solution to the billet powder was 7:93, and the billet granules were obtained by sieving and granulating. The diameter is 0.58mm, and after natural air-drying, the moisture content of the pellets is 4.7%.

The pellets that meet the moisture content requirements are loaded into a cylindrical mold, and the green body molding pressure is 47 MPa. In order to make all parts of the green body stress evenly, the pressure is maintained for 35 s to obtain a porous glass-ceramic green body.

The porous glass-ceramic green body is placed in a tunnel kiln and heated continuously in two stages. The first stage: the heating rate is set to 8°C/min, and the temperature in the kiln is gradually heated from room temperature to 1000°C. The second stage: set the heating rate to 4 °C/min, the temperature in the kiln is gradually increased from 1000 °C to 1180 °C, the holding time is 60min, and the furnace is naturally cooled to room temperature to obtain porous glass-ceramics.

After testing, the main phases of the porous glass-ceramic prepared by the method of Example 3 are cordierite, mullite and iron spinel, the linear expansion rate is 10.16%, the porosity is 55.78%, and the bulk density is 1.33g/cm ³ , the water absorption rate is 0.39%.

To sum up, the present invention uses coal gangue as a raw material to prepare porous glass-ceramics, which provides a new resource utilization approach for other solid wastes such as coal gangue.

Although the present invention has been described above in connection with the exemplary embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made in the exemplary embodiments of the present invention without departing from the spirit and scope defined by the appended claims. Change.

Claims (10)

1. a method for preparing porous glass-ceramic from coal gangue, is characterized in that, described method comprises the following steps: Mixing coal gangue powder and asbestos tailing powder evenly, or mixing coal gangue powder and pore-forming agent uniformly, to obtain billet powder; The obtained preformed powder and the binder are evenly mixed, granulated and dried to obtain preformed granules; Molding the blank-making pellets to obtain a green body of porous glass-ceramic; The porous glass-ceramic green body is heat-treated and cooled to obtain the porous glass-ceramic; Among them, coal gangue powder is obtained by pretreatment of coal gangue; asbestos tailings powder is obtained by pretreatment of asbestos tailings. 2 . The method for preparing porous glass-ceramics from coal gangue according to claim 1 , wherein the mass ratio of the coal gangue powder to the asbestos tailing powder is 70-90:10-30. 3 . 3. The method for preparing porous glass-ceramic from coal gangue according to claim 1, wherein the mineral phase of the coal gangue comprises quartz and kaolin; The loss on ignition of the coal gangue is 11.34-23.48%; The coal gangue includes the following components by mass percentage: 20.21%-68.16% SiO ₂ , 7.3%-50.41% Al ₂ O ₃ , 7.24%-20.58% Fe ₂ O ₃ , 3.41%-7.18% CaO, 0.66% %～4.42%TiO ₂ . 4. The method for preparing porous glass-ceramic from coal gangue according to claim 1, wherein the mineral phase of the asbestos tailings comprises serpentine and brucite; The loss on ignition of the asbestos tailings is 6.38-16.31%; The asbestos tailings include the following components by mass percentage: 20.14%-60.42% MgO, 15.68%-55.32% SiO ₂ , 5.19%-30.58% Fe ₂ O ₃ , 2.16%-10.24% CaO. 5 . The method for preparing porous glass-ceramics from coal gangue according to claim 1 , wherein the pore-forming agent comprises one or more of polyurethane foam pore-forming agent, silicon carbide, borax and calcium carbonate. 6 . 6. The method for preparing porous glass-ceramics from coal gangue according to claim 1, wherein the pretreatment comprises roasting, grinding and homogenization; wherein, The roasting temperature of coal gangue is 750～800℃, the roasting temperature of asbestos tailings is 850～900℃, the holding time is 30～60min, the heating rate is controlled at 5～8℃/min; the heating time is controlled at 100～180min; The particle size of the blank-making powder is 0.025-0.070 mm. 7. The method for preparing porous glass-ceramic from coal gangue according to claim 1, wherein the binder comprises 5-8wt% polyvinyl alcohol solution; The weight ratio of the binder to the blank-making powder is 5-10:90-95; The particle size of the blank-making pellets is 0.22 mm to 0.86 mm; the moisture content of the blank-making pellets is 4% to 6%; The pressure for molding the blank-making pellets is 20-50 MPa, and the pressure is maintained for 10-40 s. 8. The method for preparing porous glass-ceramic from coal gangue according to claim 1, wherein the heat treatment comprises two-stage continuous sintering; wherein, In the first stage, the heating rate is controlled to be 5 to 8 °C/min, and the temperature is gradually heated from room temperature to 900 to 1000 °C; In the second stage, the heating rate is controlled to be 2 to 5°C/min, and the temperature is continued from 900 to 1000°C to 1100°C to 1200°C; Incubate for 10 to 60 minutes, and then naturally cool to room temperature. 9. A porous glass-ceramic using coal gangue as a raw material, wherein the porous glass-ceramic comprises the method for preparing porous glass-ceramic from coal gangue according to any one of claims 1 to 8. of porous glass-ceramic. 10. The porous glass-ceramic using coal gangue as a raw material according to claim 9, wherein the phase of the porous glass-ceramic comprises cordierite, mullite and iron spinel; The linear expansion rate of the porous glass-ceramic is 9.41-10.22%, the porosity is 42.13-73.25%, the bulk density is 1.29-1.37 g/cm ³ , and the water absorption rate is 0.35-0.44%.

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