CN111559921A

CN111559921A - Foamed ceramic and preparation method thereof

Info

Publication number: CN111559921A
Application number: CN202010386152.5A
Authority: CN
Inventors: 张思奇; 李克庆; 王宏雨; 倪文; 乌鹏飞
Original assignee: University of Science and Technology Beijing USTB
Current assignee: Qingdao Qingli Environment Protection Equipment Co ltd
Priority date: 2020-05-09
Filing date: 2020-05-09
Publication date: 2020-08-21
Anticipated expiration: 2040-05-09
Also published as: CN111559921B

Abstract

The invention relates to the field of building materials, and particularly provides a preparation method of foamed ceramic, which comprises the following steps: selecting raw materials; grinding and mixing raw materials: grinding the raw materials, adding water, and then carrying out wet grinding to obtain slurry; and (3) suction filtration and drying: filtering out the water in the slurry to form a solid briquette, and drying to obtain a billet body; blank die filling: preparing the blank into powder, and pouring the powder blank into a die; and (3) high-temperature sintering: the mould with the blank is placed in an electric furnace, the foaming temperature is adjusted to 1170-1200 ℃, the temperature is kept for 60-90min, then the mould is rapidly cooled to 900-1000 ℃, and then the mould is cooled to prepare the foamed ceramic.

Description

Foamed ceramic and preparation method thereof

Technical Field

The invention relates to the field of green building materials, in particular to foamed ceramic and a preparation method thereof.

Background

The tailings serving as secondary resources with the largest quantity and lower utilization rate in the bulk solid waste are a resource utilization problem to be solved urgently in China. A large amount of stockpiled tailings occupy land area, influence water and soil vegetation and ecological environment of a mining area, and have certain potential safety hazards such as collapse and landslide. The foamed ceramic is a high-porosity fireproof heat-insulating material for buildings. By virtue of the superior performances of light weight, thin body, heat insulation, sound insulation, moisture and fire prevention, high strength, good cold and hot stability and the like, the heat-insulation board can be applied to the aspects of external wall heat insulation, building internal baffles, fire-proof isolation belts and the like. Its main raw materials are silicon-aluminium oxide and some alkali metal oxides and foaming agent. According to the chemical component characteristics, the gold tailings can be used for replacing the silicon-aluminum oxide raw material. Therefore, the secondary utilization of tailing resources can be realized, the resource utilization rate is improved, and the stability of the foamed ceramic can be enhanced. The foamed ceramic product prepared by using the gold tailings can improve the utilization rate of the tailings and the added value of the product, thereby realizing the cyclic and efficient utilization of mineral resources. However, in view of the characteristics of the gold tailings, the problems of complex process, long sintering time and high sintering temperature exist when the gold tailings are used for preparing the foamed ceramic at present, and the prepared foamed ceramic has the problems of low strength, heavy weight and poor heat insulation effect.

Disclosure of Invention

The present invention solves the above-mentioned technical problems in the related art at least to some extent. Therefore, the invention provides the foamed ceramic and the preparation method thereof, on one hand, under the condition of doping a large amount of gold tailings, the sintering time is greatly shortened, the sintering temperature is reduced, the energy is saved, and on the other hand, the foamed ceramic with light weight, high strength and good heat insulation effect is obtained.

In order to achieve the above object, a first aspect of the present invention provides a method for preparing a foamed ceramic, comprising the steps of:

selecting raw materials: 55-80 parts of gold tailings, 5-20 parts of bentonite, 5-10 parts of kaolin, 5-10 parts of talc, 0-5 parts of calcite, 0.4-1.2 parts of silicon carbide powder and 0.4-1.2 parts of water reducing agent;

grinding and mixing raw materials: grinding the raw materials, adding water, and then carrying out wet grinding to obtain slurry;

and (3) suction filtration and drying: filtering out the water in the slurry to form a solid briquette, and drying to obtain a billet body;

blank die filling: preparing the blank into powder, and pouring the powder blank into a die;

and (3) high-temperature sintering: and (3) placing the die with the blank in an electric furnace, adjusting the foaming temperature to 1170-1200 ℃, preserving the temperature for 60-90min, quenching to 900-1000 ℃, and then cooling to prepare the foamed ceramic.

In a second aspect, the invention provides a foamed ceramic prepared by the above method.

In addition, the preparation method of the foamed ceramic according to the invention can also have the following additional technical characteristics:

according to one embodiment of the invention, the step of adjusting the foaming temperature comprises:

firstly, the temperature is raised to 300 ℃ in 30min at room temperature, then raised to 600 ℃ in 60min, then raised to 1030 ℃ in 60min, and finally raised to 1170-1200 ℃ in 30 min.

According to one embodiment of the invention, the gold tailings comprise the following components: in parts by weight, SiO₂75-80 parts of Al₂O₃9-13 parts, K₂O2-6 parts, MgO 0-1 part, Na₂0-1 part of O, Fe₂O₃1-4 parts of CaO and 1-3 parts of CaO.

According to one embodiment of the invention, the bentonite comprises the following ingredients: in parts by weight, SiO₂68-72 parts of Al₂O₃13-17 parts, K₂1-4 parts of O, 1-3 parts of MgO and Na₂0-1 part of O, Fe₂O₃1-3 parts of CaO and 1-3 parts of CaO.

According to one embodiment of the invention, the kaolin comprises the following ingredients: in parts by weight, SiO₂68-72 parts of Al₂O₃13-17 parts, K₂O2-6 parts, MgO 0-1 part, Na₂0-1 part of O, Fe₂O₃1-3 parts of CaO and 0-1 part of CaO.

According to one embodiment of the invention, the talc comprises the following ingredients: in parts by weight, SiO₂15-20 parts of MgO 35-45 parts of Al₂O₃0 to 1 part, K₂0 to 1 portion of O, Na₂0-1 part of O, Fe₂O₃0-1 part of CaO and 0-1 part of CaO.

According to one embodiment of the present invention, in the step of grinding and mixing the raw materials, the water content of the mixture is 40% to 50% after the water is added.

According to one embodiment of the present invention, the mass ratio of the bentonite to the kaolin is 2: 1.

according to one embodiment of the invention, the compressive strength of the foamed ceramic is 7.0-7.6MPa, and the bulk density is 390.6-407.8kg/m³The thermal conductivity coefficient is 0.067-0.068W/(m.k).

Compared with the prior art, the invention has the following beneficial effects:

1. and a large amount of gold tailings are doped, so that the utilization rate of solid waste is improved.

2. By doping a proper amount of bentonite, the sintering time is shortened, and the energy is saved; specifically, bentonite is a non-metallic mineral product with montmorillonite as a main mineral component, and the montmorillonite can be strongly expanded when meeting water and has strong water absorption. Montmorillonite is a 2:1 type clay mineral, and is a structural unit layer composed of two silicon-oxygen tetrahedral sheets and one aluminum-oxygen octahedral sheet. The sintering property of the bentonite can increase the plasticity, the bending resistance and the strength of the ceramic, so that the product is not easy to crack, and the sintering time and the energy consumption are reduced. In addition, the suspension property and the stability are greatly enhanced, the suspension of water in the paste is stable, and the water can be used as a tackifier to improve the adhesion of raw materials. The bentonite is added to facilitate ball milling and has lubricating effect in the grinding process.

3. The mass ratio of bentonite to kaolin in this example is 2:1, ion exchange can be carried out between bentonite and kaolin, so that the performance of the foamed ceramic has a synergistic effect, and particularly, the kaolin is aqueous aluminosilicate and is a triclinic system, and no cations or water molecules exist between structural layers. The bentonite is a non-metal mineral product with montmorillonite as a main mineral component, the montmorillonite is also called microcrystalline kaolinite, is a silicate clay mineral with a lamellar structure and a flaky crystal, is a monoclinic system, and has cations or water molecules between structural layers. Cations such as Cu, Mg, Na, K and the like in the interlayer structure are easily exchanged by other cations, so that the ion exchange of the two is realized.

4. This application greatly reduced the foaming temperature.

5. The foamed ceramic prepared by the preparation method has excellent properties of high strength, light weight and good heat insulation effect.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a photograph showing a cross section of a foamed ceramic prepared in examples 1 to 4;

FIG. 2 is a photograph of a cross section of the foamed ceramics prepared in comparative examples 1-2;

FIG. 3 is a photograph showing a cross section of the foamed ceramics prepared in comparative examples 3 to 5.

Detailed Description

Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

Example 1

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: 58 parts of gold tailings, 20 parts of bentonite, 9 parts of kaolin, 9 parts of talcum, 4 parts of calcite, 0.4 part of silicon carbide powder and 0.4 part of water reducing agent;

(2) grinding and mixing raw materials: grinding the raw materials to below 200 meshes by using a rapid sample preparation machine for 4 minutes, adding water to ensure that the water content of the slurry is 42%, and wet-grinding the slurry for 4 hours by using a planetary ball mill to obtain slurry, so that the raw materials are fully and uniformly mixed;

(3) and (3) suction filtration and drying: pouring the slurry into a suction filter to filter water to obtain a solid billet, and drying the solid billet in a drying box at the temperature of 55 ℃ for 10.5 hours to obtain a dried billet;

(4) blank die filling: rolling the dried blank into powder with a rolling pin, wherein the particle size is less than 2mm, enclosing into a 15 x 10cm mould by using refractory bricks, wrapping demoulding paper around the mould, and flatly spreading the powder blank in the mould;

(5) and (3) high-temperature sintering: cooling the mixture in an electric furnace at the initial temperature of room temperature for 30min to 300 ℃, 60min to 600 ℃, 60min to 1030 ℃, 30min to 1175 ℃, keeping the temperature for 60min, and quenching the mixture to 900 ℃ along with the furnace.

Example 2

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: according to parts by weight, 65 parts of gold tailings, 17 parts of bentonite, 9 parts of kaolin, 9 parts of talc, 0 part of calcite, 0.9 part of silicon carbide powder and 0.9 part of water reducing agent;

(2) grinding and mixing raw materials: grinding the raw materials to below 200 meshes by using a rapid sample preparation machine for 4 minutes, adding water to ensure that the water content of the slurry is 42%, wet-grinding the slurry by using a planetary ball mill for 6 hours to obtain slurry, and fully and uniformly mixing the raw materials;

(3) and (3) suction filtration and drying: pouring the slurry into a suction filter to filter water to obtain a solid billet, and drying the solid billet in a drying box at the temperature of 55 ℃ for 12 hours to obtain a dried billet;

(5) and (3) high-temperature sintering: cooling in an electric furnace at room temperature for 30 min-300 deg.C, 60 min-600 deg.C, 60 min-1030 deg.C, 30 min-1190 deg.C, maintaining the temperature for 65min, and quenching to 900 deg.C.

Example 3

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: 70 parts of gold tailings, 14 parts of bentonite, 6 parts of kaolin, 6 parts of talcum, 4 parts of calcite, 0.9 part of silicon carbide powder and 0.9 part of water reducing agent by weight, wherein the used raw materials are the same as those in example 1;

(2) grinding and mixing raw materials: grinding the raw materials to below 200 meshes by using a rapid sample preparation machine for 4 minutes, adding water to ensure that the water content of the slurry is 46%, and wet-grinding the slurry by using a planetary ball mill for 5.5 hours to obtain slurry, so that the raw materials are fully and uniformly mixed;

(5) and (3) high-temperature sintering: cooling the mixture in an electric furnace at the initial temperature of room temperature for 30min to 300 ℃, 60min to 600 ℃, 60min to 1030 ℃, 30min to 1185 ℃, keeping the temperature for 75min, and quenching the mixture to 900 ℃.

Example 4

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: 78 parts of gold tailings, 12 parts of bentonite, 5 parts of kaolin, 5 parts of talcum, 0 part of calcite, 1.2 parts of silicon carbide powder and 1.2 parts of water reducing agent;

(2) grinding and mixing raw materials: grinding the raw materials to below 200 meshes by using a rapid sample preparation machine for 4 minutes, adding water to ensure that the water content of the slurry is 46%, and wet-grinding the slurry for 6 hours by using a planetary ball mill to obtain slurry, so that the raw materials are fully and uniformly mixed;

In order to verify the influence of bentonite on sintering time, foaming temperature and bentonite content on the performance of the foamed ceramic, the following comparative examples are provided.

Comparative example 1

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: 76 parts of gold tailings, 0 part of bentonite, 10 parts of kaolin, 10 parts of talcum, 4 parts of calcite, 1 part of silicon carbide powder and 1 part of water reducing agent;

(2) grinding and mixing raw materials: grinding the raw materials to below 200 meshes by using a rapid sample preparation machine for 4 minutes, adding water to ensure that the water content of the slurry is 46%, and wet-grinding the slurry by using a planetary ball mill for 6.5 hours to obtain slurry, so that the raw materials are fully and uniformly mixed;

(3) and (3) suction filtration and drying: pouring the slurry into a suction filter to filter water to obtain a solid briquette, and drying the solid briquette in a drying box at the temperature of 55 ℃ for 12 hours to obtain a dried briquette.

(4) Blank die filling: and crushing the dried blank into powder by using a rolling pin, wherein the particle size is less than 2mm, enclosing into a 15 x 10cm mould by using refractory bricks, wrapping demoulding paper at the periphery, and flatly paving the powder blank in the mould.

(5) And (3) high-temperature sintering: cooling the mixture in an electric furnace at the initial temperature of room temperature for 30min to 300 ℃, 60min to 600 ℃, 60min to 1030 ℃, 30min to 1185 ℃, keeping the temperature for 100min, and quenching the mixture to 900 ℃ along with the furnace.

Comparative example 2

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: 65 parts of gold tailings, 17 parts of bentonite, 9 parts of kaolin, 9 parts of talcum, 0 part of calcite, 0.9 part of silicon carbide powder and 0.9 part of water reducing agent, wherein the parts are the same as those in example 2;

(5) And (3) high-temperature sintering: cooling in an electric furnace at room temperature for 30 min-300 deg.C, 60 min-600 deg.C, 60 min-1030 deg.C, 30 min-1165 deg.C, and holding temperature for 60 min-900 deg.C.

Comparative example 3

A preparation method of foamed ceramic comprises the following steps:

(5) And (3) high-temperature sintering: cooling the mixture with an electric furnace at the initial temperature of room temperature for 30min to 300 ℃, 60min to 600 ℃, 60min to 1030 ℃, 30min to 1205 ℃, keeping the temperature for 60min, and quenching the mixture to 900 ℃.

Comparative example 4

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: according to parts by weight, 65 parts of gold tailings, 16 parts of bentonite, 8 parts of kaolin, 9 parts of talc, 0 part of calcite, 0.9 part of silicon carbide powder and 0.9 part of water reducing agent;

Comparative example 5

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: according to parts by weight, 65 parts of gold tailings, 17 parts of bentonite, 0 part of kaolin, 9 parts of talc, 0 part of calcite, 0.9 part of silicon carbide powder and 0.9 part of water reducing agent;

Comparative example 6

A preparation method of foamed ceramic comprises the following steps:

(1) selecting raw materials: 65 parts of gold tailings, 25 parts of bentonite, 9 parts of kaolin, 9 parts of talcum, 0 part of calcite, 0.9 part of silicon carbide powder and 0.9 part of water reducing agent;

The foamed ceramics prepared in examples 1 to 4 and comparative examples 1 to 6 were cut and then subjected to a performance test, wherein photographs of the cut of the foamed ceramics of examples 1 to 4 and comparative example 4 are shown in FIG. 1, photographs of the cut of the foamed ceramics of comparative examples 1 to 3 are shown in FIG. 2, and photographs of the cut of the foamed ceramics of comparative examples 5 to 6 are shown in FIG. 3. The performance test results are shown in table 1:

table 1: comparison of the Properties of the foamed ceramics obtained in examples 1 to 4 and comparative examples 1 to 6

As can be seen from Table 1, the foamed ceramics of examples 1 to 4 have excellent properties of light weight, high strength and heat insulation as compared with those of comparative examples 1 to 3, 5 to 6. The foamed ceramics of examples 1-4 were slightly inferior in performance compared to the foamed ceramics of comparative example 4.

It is worth mentioning that the mass ratio of bentonite to kaolin in comparative example 4 is 2:1, the ion exchange effect between bentonite and kaolin is better, so that the synergistic interaction effect on the foamed ceramic is achieved, specifically, the bentonite and the kaolin are different in space structure, the kaolin is an aqueous aluminosilicate and is a triclinic system, and cations or water molecules do not exist between structural layers. Montmorillonite, also known as microcrystalline kaolinite, is a silicate clay mineral with a layered structure and sheet crystals, is a monoclinic system, and has cations or water molecules between structural layers. Cations such as Cu, Mg, Na, K, etc. of the interlayer structure are easily exchanged with other cations, so that ion exchange between bentonite and kaolin is possible.

And the foamed ceramic prepared in comparative example 5, to which no kaolin was added, had very poor properties due to the failure of ion exchange with bentonite.

Specifically, the foamed ceramic prepared in comparative example 1 without bentonite is greatly increased in total sintering time on one hand, and particularly in a high-temperature heat-preservation foaming stage, so that the production cost is increased. On the other hand, the foamed ceramic in the comparative example 1 has low compressive strength, large volume density and large thermal conductivity coefficient, namely, the performances of the foamed ceramic in the comparative example 1 are inferior to those of the foamed ceramics in the examples 1 to 4.

Compared with the example 2, the final foaming temperature is reduced under the same proportioning condition, the temperature is kept for the same time, the height of the obtained foamed ceramic is only 3cm, as shown in fig. 2, the pore size of the foamed ceramic is obviously uneven, the phenomenon that the bottom is not completely foamed exists, and as can be seen from table 1, the performances of the foamed ceramic in the example 2 are inferior to those of the example 2.

Compared with the example 2, the comparative example 3 has the advantages that the final foaming temperature is increased under the same proportioning condition, and the foaming states are different when the heat is preserved for different time. The foamed ceramic does not obviously rise in the first 30min, and obviously rises within the heat preservation time period of 50-60 min. At 1205 ℃, the foaming speed was too fast, the pore size was significantly uneven, and a large number of interconnected pores appeared, and it can be seen from table 1 that the foamed ceramics in comparative example 3 were inferior to those in example 2 in each performance. From the above analysis, it can be found that the control of the foaming temperature and time has a very important role in the properties of the foamed ceramics.

Comparative examples 1 and 6 are to verify the effect of the bentonite content on the foamed ceramic, wherein, compared with example 2, the bentonite blending amount in comparative example 1 is 0, the bentonite blending amount in comparative example 6 is higher, and as can be seen from table 1, too low or too high blending amount of bentonite can cause the performance of the foamed ceramic to be poor, and it is noted that the bentonite can absorb moisture, has good cohesive force, enables the raw materials to be fully fused, and the structure of montmorillonite in the bentonite can be changed along with the increase of temperature, and the cohesive force of the bentonite can be gradually reduced. When the temperature is continuously increased to 600-700 ℃, the structure of montmorillonite in the bentonite is completely destroyed; in which case the bentonite will no longer have cohesive strength. The blending amount of the bentonite cannot be too high, otherwise, the viscosity of the slurry is too high, and the operation is not facilitated. Because the montmorillonite is a dioctahedral lamellar structure, after water for wet grinding is mixed in the excessively high bentonite mixture, part of water is adsorbed by the bentonite and becomes bound water of a structural unit of the bentonite, so that the fluidity of slurry is reduced, the grinding time is prolonged, the required grinding effect cannot be achieved, and the performance of a foamed ceramic product is influenced to a certain extent. The bentonite in comparative example 6 is incorporated in an excessively high amount, and after sufficient moisture absorption, the bentonite undergoes a plasticizing reaction, resulting in a decrease in strength of the foamed ceramic. Despite the bentonite contentSmall amount of SiO₂And Al₂O₃However, the ratio of the 2 active ingredients is low, the contribution of the 2 active ingredients to the strength of the foamed ceramic is small, and the adverse effect of plasticization of the bentonite after water absorption on the foamed ceramic cannot be changed.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. The preparation method of the foamed ceramic is characterized by comprising the following steps of:

blank die filling: preparing the blank into powder with the particle size of less than 2mm, and pouring the powdery blank into a die;

2. The method of preparing a foamed ceramic according to claim 1, wherein the step of adjusting the foaming temperature comprises:

3. The method for preparing the foamed ceramic according to claim 1, wherein the gold tailings comprise the following components: in parts by weight, SiO₂75-80 parts of Al₂O₃9-13 parts, K₂O2-6 parts, MgO 0-1 part, Na₂0-1 part of O, Fe₂O₃1-4 parts of CaO and 1-3 parts of CaO.

4. The method for preparing a ceramic foam according to claim 1, wherein the bentonite comprises the following components: in parts by weight, SiO₂68-72 parts of Al₂O₃13-17 parts, K₂1-4 parts of O, 1-3 parts of MgO and Na₂0-1 part of O, Fe₂O₃1-3 parts of CaO and 1-3 parts of CaO.

5. The method for preparing a ceramic foam according to claim 1, wherein the kaolin comprises the following components: in parts by weight, SiO₂68-72 parts of Al₂O₃13-17 parts, K₂O2-6 parts, MgO 0-1 part, Na₂0-1 part of O, Fe₂O₃1-3 parts of CaO and 0-1 part of CaO.

6. The method of claim 1, wherein the talc comprises the following components: in parts by weight, SiO₂15-20 parts of MgO 35-45 parts of Al₂O₃0 to 1 part, K₂0 to 1 portion of O, Na₂0-1 part of O, Fe₂O₃0-1 part of CaO and 0-1 part of CaO.

7. The method of claim 1, wherein the water content of the mixture is 40-50% after the water is added in the step of grinding and mixing the raw materials.

8. The method for preparing a ceramic foam according to any one of claims 1 to 7, wherein the mass ratio of the bentonite to the kaolin is 2: 1.

9. a foamed ceramic produced by the method for producing a foamed ceramic according to any one of claims 1 to 8.

10. The foamed ceramic of claim 9, wherein the foamed ceramic has a compressive strength of 7.0 to 7.6MPa and a bulk density of 390.6 to 407.8kg/m³The thermal conductivity coefficient is 0.067-0.068W/(m.k).