Low-sintering temperature light-weight high-strength shale ceramsite and preparation method thereof

Abstract

The application discloses a low-sintering-temperature light-weight high-strength shale ceramisite and a preparation method thereof, relates to the technical field of artificial light aggregate for concrete, and discloses the following technical scheme: shale powder is used as main material, biomass powder is used as a pore-forming template, and one or more of waste glass powder, wood ash, red mud and fluorite is used as a sintering aid to form raw materials; the raw materials are weighed according to a proportioning ratio and then subjected to homogenization treatment to obtain uniformly dispersed composite powder; the composite powder is prepared into ceramisite raw material by using a granulator; the dried ceramisite raw material is subjected to high-temperature sintering in an inert atmosphere or a reducing atmosphere; and the sintered ceramisite is cooled in a furnace to obtain the low-sintering-temperature light-weight high-strength shale ceramisite. The preparation process is simple, energy consumption is low, carbon emission is low, and cost is low; and the prepared shale ceramisite has a dense surface glaze layer and a porous core structure, and has the advantages of low density and high strength.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of artificial light aggregate for concrete, and particularly relates to a low-sintering-temperature light-weight high-strength shale ceramsite and a preparation method thereof. BACKGROUND

[0002] Ceramsite is a commonly used light aggregate for concrete, which has the advantages of low density, high strength and good durability. At present, light-weight high-strength shale ceramsite is mainly prepared based on a high-temperature sintering process, that is, through component design and precise heat treatment system regulation, the three of liquid phase amount, liquid phase viscosity and gas production rate in the ceramsite in the high-temperature sintering stage are matched with each other, and the gas produced by the liquid phase at high temperature is bound, so that the ceramsite structure is expanded. In order to realize the high-temperature expansion, the existing process needs a sintering temperature as high as 1200 DEG C, which has the problems of high energy consumption and large carbon emission, and the existing process is difficult to realize fine regulation of the pore structure in the ceramsite, and the shale ceramsite prepared by the process generally has the problems of prominent contradiction between low density and high strength, large performance fluctuation and high water absorption. SUMMARY

[0003] One of the purposes of the present application is to provide a preparation method of low-sintering-temperature light-weight high-strength shale ceramsite, so as to reduce the sintering temperature and make the prepared shale ceramsite have the performance of light weight and high strength.

[0004] In order to solve the above technical problems, the present application adopts the following technical scheme: a preparation method of low-sintering-temperature light-weight high-strength shale ceramsite, comprising the following steps:

[0005] (1) taking shale powder as a main material, taking biomass powder as a pore-forming template, and taking one or more of waste glass powder, wood ash, red mud and fluorite as a sintering aid, so as to form a raw material;

[0006] (2) homogenizing the raw material after weighing according to the proportion to obtain a uniformly dispersed composite powder;

[0007] (3) preparing the composite powder into ceramsite raw material by using a granulator, sintering the dried ceramsite raw material in an inert atmosphere or a reducing atmosphere, cooling the sintered ceramsite raw material in the furnace, and obtaining the low-sintering-temperature light-weight high-strength shale ceramsite.

[0008] Preferably, the particle size of the shale powder is less than 0.045 mm, the particle size of the biomass powder is less than 0.023 mm, and the particle size of the waste glass powder, wood ash, red mud and fluorite is less than 0.045 mm.

[0009] More preferably, the biomass powder is one or a combination of sawdust, rice husk powder and straw powder.

[0010] More preferably, the particle size of the prepared ceramsite raw material is 3-20 mm.

[0011] More preferably, the temperature of the high-temperature sintering is 800-1000℃.

[0012] More preferably, the high-temperature sintering is performed by first holding at 300-550℃ for 0.5-3h, then heating to 800-1000℃ and holding for 20-60min.

[0013] More preferably, the mass ratio of the shale powder in the raw material is not less than 65%.

[0014] More preferably, the mass ratio of the biomass powder in the raw material is 1.5-15%.

[0015] More preferably, the mass ratio of the sintering aid in the raw material is 10-35%, wherein the waste glass powder is 8-25%, the wood ash is 0-10%, the red mud is 0-25%, and the fluorite is 0-5%.

[0016] In step (2), the homogenization treatment can be completed by using a ball mill or a powerful mixer or a powder mixing machine and the like.

[0017] In step (3), the equipment for preparing the ceramsite raw material can use a disc granulator or an extruding machine, and the drying temperature of the ceramsite raw material is 100-110℃. In addition, the high-temperature sintering process of the ceramsite raw material needs to be performed in a reducing or inert atmosphere throughout to ensure that the biomass pore-forming template is not ablated. The specific high-temperature sintering process includes the following stages: first, heating from room temperature to 300-500℃, and holding at the target temperature for 1-2h to ensure that the organic matter in the biomass pore-forming template is fully decomposed; then, heating to 800-1000℃, and holding at the highest temperature for 20-60min to ensure that the ceramsite reaches a high sintering degree. The sintered ceramsite has a dense glaze layer on the surface, and the core is a porous structure occupied by the carbonized product of the biomass pore-forming template.

[0018] In addition, the application also provides a low-sintering-temperature lightweight high-strength shale ceramsite prepared by the above-mentioned preparation method.

[0019] The application uses sawdust, rice husk powder and straw powder as the pore-forming template, and performs high-temperature sintering in a reducing or inert atmosphere to ensure that the biomass powder pore-forming template is not ablated; meanwhile, uses waste glass powder, wood ash, red mud and fluorite as the sintering aid, and through the regulation of the components, the eutectic temperature of the ceramsite-forming raw material is reduced, and the lightweight high-strength shale ceramsite is prepared at a sintering temperature of 800-1000℃.

[0020] Compared with the prior art, the sintering temperature of the shale ceramsite can be reduced from 1200 DEG C to 800-1000 DEG C, and the pores in the ceramsite are mainly derived from the biomass pore-forming template added in the raw materials, the difficulty of pore forming is significantly reduced, the controllability is higher, and the pore structure can be designed to a certain extent. In addition, the lightweight high-strength shale ceramsite prepared by the application has a dense surface glaze layer and a porous core structure, and has the advantages of low density and high strength. In addition, the preparation process of the application is simple, low in energy consumption, low in carbon emission and cost, and is more suitable for industrialized production. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a schematic diagram of the preparation method of the application;

[0022] Figure 2 The figure is a schematic diagram of the shale ceramsite prepared in Example 4 of the application;

[0023] Figure 3 The figure is a schematic diagram of the 3D-CT reconstruction of the shale ceramsite prepared in Example 4 of the application;

[0024] Figure 4 The figure is a schematic diagram of the microstructure of the shale ceramsite prepared in Example 4 of the application. DETAILED DESCRIPTION

[0025] In order to facilitate the understanding of those skilled in the art, the application will be further described below in conjunction with the embodiments and the drawings, and the content mentioned in the embodiments is not a limitation of the application.

[0026] Overall, the following embodiments are based on the same technical concept (refer to Figure 1The process shown): that is, taking shale powder with appropriate particle size as the main material, taking micron-sized biomass powder as the pore-forming template, taking one or more of waste glass powder, red mud, wood ash, and fluorite powder as the sintering aid, then weighing the above materials according to the proportion, homogenizing, forming, drying, and then preparing the ceramsite raw material through a granulator, it should be noted that the binder used in the granulation process in the examples belongs to the common materials in the granulation process. Then, the dried ceramsite raw material is sintered in a reducing or inert atmosphere to ensure that the biomass pore-forming template and its carbonized products are not ablated, and the lightweight high-strength shale ceramsite is obtained after sintering. In the following examples, the particle size of the shale powder used is less than 0.045 mm, the particle size of the biomass powder is less than 0.023 mm, and the particle size of the sintering aid is less than 0.045 mm. In the raw material ratio for preparing ceramsite, the mass ratio of shale powder is not less than 65%, the mass ratio of sintering aid is 10-35%, and the mass ratio of biomass pore-forming template is 1.5%-15%. The main difference between the examples is that the types of shale powder, biomass pore-forming template, sintering aid, the ratio of various raw materials, and the conditions of heat treatment are different. Example 1

[0027] I. Preparation of ceramsite raw material.

[0028] Raw materials: 325 mesh shale powder, 600 mesh sawdust powder (biomass powder pore-forming template), waste glass powder and fluorite powder (sintering aid), paper pulp waste liquid (binder), the shale in the above raw materials is a self-made shale powder, and the other raw materials are mainly enterprise solid waste or commercially available raw materials.

[0029] Equipment: planetary ball mill, disc granulator, electric drying oven, muffle furnace.

[0030] 1. Weigh according to the mass ratio of shale: glass powder: fluorite powder: sawdust powder 70:20:2:8, then mix in the planetary ball mill, the ball-to-material ratio is 1:1, the rotation speed is 300r / min, and the processing time is 20min, finally get the homogenized powder for standby.

[0031] 2. Start the disc granulator, add 200g of homogenized powder to the mixing disc, use a spray device to spray an appropriate amount of paper pulp waste liquid into the mixing disc, mix for 1-5min, then spray more paper pulp waste liquid according to the balling situation of the material in the mixing disc; spray an appropriate amount of paper pulp waste liquid into the mixing disc, then slowly sieve in the homogenized powder, and spray more paper pulp waste liquid according to the actual situation; repeat the above steps, the ceramsite raw material balls in the mixing disc continue to grow, and the ceramsite raw material with a particle size of 10-20mm is treated by mechanical screening.

[0032] II. Heat treatment of ceramsite raw material balls.

[0033] 1. The raw ceramsite is dried in a forced air drying oven, and the drying schedule is 105℃ for 24h.

[0034] 2. The dried raw ceramsite is loaded into a high-alumina bauxite crucible, and the surface of the raw ceramsite is covered with a layer of coke powder with a thickness of not less than 1cm. The crucible is then placed in a muffle furnace for heat treatment. The heat treatment schedule is as follows: the temperature is raised from room temperature to 450℃ at a rate of 10℃ / min, and the temperature is maintained at 450℃ for 2h. Then the temperature is raised from 450℃ to 950℃ at a rate of 10℃ / min, and the temperature is maintained at 950℃ for 1h. The furnace is then cooled, and the raw ceramsite is mechanically sieved to obtain the lightweight high-strength shale ceramsite.

[0035] III. Performance index testing.

[0036] The performance index of the lightweight high-strength shale ceramsite prepared in this embodiment is as follows: apparent density 1.25g / cm 3 , bulk density 711kg / m 3 , cylinder compressive strength 9.8MPa, and water absorption 3.1%. Example 2

[0037] I. Preparation of raw ceramsite.

[0038] Raw materials: 325 mesh shale powder, 600 mesh rice husk powder (biomass powder pore-forming template), waste glass powder, wood ash, fluorite powder (sintering aid), molasses water waste liquid (15wt%, binder), and the above-mentioned raw materials, with the shale being a self-made shale powder, and the other raw materials being mainly enterprise solid waste or commercially available raw materials.

[0039] Equipment: intensive mixer, disc granulator, electric drying oven, and muffle furnace.

[0040] 1. The raw materials are weighed according to the mass ratio of shale:glass powder:wood ash:fluorite powder:rice husk powder of 73:18:1:2:6, and then mixed in an intensive mixer at a speed of 200r / min for 15min to obtain a homogenized powder for standby use.

[0041] 2. The disc granulator is started, 200g of the homogenized powder is added to the mixing disc, and an appropriate amount of molasses aqueous solution is sprayed into the mixing disc. After mixing for 1-5min, the molasses aqueous solution is appropriately supplemented according to the balling situation of the materials in the mixing disc. An appropriate amount of paper pulp waste liquid is sprayed into the mixing disc, and the homogenized powder is slowly sieved in. The molasses aqueous solution is appropriately supplemented according to the actual situation. The above steps are repeated, and the raw ceramsite balls in the mixing disc continue to grow. The raw ceramsite with a particle size of 10-20mm is mechanically sieved.

[0042] II. Heat treatment of the raw ceramsite balls.

[0043] 1. Dry the raw ceramsite in a forced air drying oven at 105°C for 24 hours.

[0044] 2. Place the dried raw ceramsite balls in a high alumina bauxite crucible, cover the surface of the raw ceramsite balls with coke powder to a thickness of not less than 1 cm, and then place the crucible in a muffle furnace for heat treatment. The heat treatment schedule is as follows: increase the temperature from room temperature to 400°C at a rate of 10°C / min, maintain the temperature at 400°C for 2 hours, then increase the temperature from 400°C to 900°C at a rate of 10°C / min, maintain the temperature at 900°C for 1.5 hours, and then cool the furnace, and then mechanically sieve the product to obtain lightweight high-strength shale ceramsite.

[0045] III. Performance index testing.

[0046] The performance index of the lightweight high-strength shale ceramsite prepared in this embodiment is as follows: apparent density 1.48 g / cm 3 , bulk density 778 kg / m 3 , cylinder compressive strength 10.5 MPa, and water absorption 3.3%. Example 3

[0047] I. Preparation of raw ceramsite.

[0048] Raw materials: 325 mesh shale powder, 800 mesh charcoal powder (biomass powder pore-forming template), red mud powder, and fluorite powder (sintering aid), molasses aqueous solution (15 wt%, binder), the shale in the above raw materials is a self-made shale powder, and the other raw materials are mainly enterprise solid waste or commercially available raw materials.

[0049] Equipment: vibration ball mill, disc granulator, electric drying oven, vacuum muffle furnace.

[0050] 1. Weigh the raw materials according to the mass ratio of shale: red mud powder: fluorite powder: charcoal powder as 60:25:3:12, and then mix them in a vibration ball mill at a ball-to-material ratio of 2:1 for 20 minutes, and finally obtain a homogenized powder for standby use.

[0051] 2. Start the disc granulator, add 200 g of homogenized powder to the mixing disc, spray an appropriate amount of molasses aqueous solution into the mixing disc using a spraying device, mix for 1-5 minutes, and then appropriately supplement the molasses aqueous solution according to the balling situation of the material in the mixing disc; spray an appropriate amount of molasses aqueous solution into the mixing disc, and then slowly sieve in the homogenized powder, and appropriately supplement the molasses aqueous solution according to the actual situation; repeat the above steps, and continuously grow the raw ceramsite balls in the mixing disc, and mechanically sieve the raw ceramsite with a particle size of 10-20 mm.

[0052] II. Heat treatment of raw ceramsite balls.

[0053] 1. Dry the raw ceramsite in a forced air drying oven at 105°C for 24 hours.

[0054] 2. Put the dried raw ceramsite balls into a high-alumina bauxite crucible, and then place it in a vacuum muffle furnace for heat treatment. N2 is supplied throughout the heat treatment process at a flow rate of 5 L / min. The heat treatment schedule is as follows: increase the temperature from room temperature to 350°C at a rate of 10°C / min; maintain the temperature at 350°C for 1 hour; increase the temperature from 350°C to 1000°C at a rate of 10°C / min; maintain the temperature at 1000°C for 1 hour; cool down with the furnace, and then perform mechanical screening to obtain lightweight high-strength shale ceramsite.

[0055] III. Performance index testing.

[0056] The performance index of the lightweight high-strength shale ceramsite prepared in this embodiment is as follows: apparent density 1.15 g / cm 3 , bulk density 585 kg / m 3 , cylinder compressive strength 6.7 MPa, and water absorption 3.6%. Example 4

[0057] I. Preparation of raw ceramsite.

[0058] Raw materials: 325 mesh shale powder, 600 mesh straw powder (biomass powder pore-forming template), waste glass powder, and wood ash (sintering aid), paper pulp waste liquid (binder). The shale in the above raw materials is a self-made shale powder, and the other raw materials are mainly enterprise solid waste or commercially available raw materials.

[0059] Equipment: planetary ball mill, disc granulator, electric drying oven, and muffle furnace.

[0060] 1. Weigh the raw materials according to the mass ratio of shale:waste glass powder:wood powder:straw powder as 70:20:5:5, and then mix them in a planetary ball mill at a ball-to-material ratio of 1:1 and a rotation speed of 300 r / min for 20 min. Finally, obtain a homogenized powder for standby use.

[0061] 2. Start the disc granulator, add 200 g of homogenized powder to the mixing disc, and spray an appropriate amount of paper pulp waste liquid into the mixing disc using a spraying device. After mixing for 1-5 min, appropriately supplement the paper pulp waste liquid according to the balling situation of the materials in the mixing disc; spray an appropriate amount of paper pulp waste liquid into the mixing disc, and then slowly sieve in the homogenized powder. Appropriately supplement the paper pulp waste liquid according to the actual situation; repeat the above steps, and continuously grow the raw ceramsite balls in the mixing disc. Use mechanical screening to process the raw ceramsite with a particle size of 10-20 mm.

[0062] II. Heat treatment of raw ceramsite balls.

[0063] 1. The raw ceramsite is dried in a forced air drying oven, and the drying schedule is 105°C for 24h.

[0064] 2. The dried raw ceramsite is loaded into a high-alumina bauxite crucible, and the surface of the raw ceramsite is covered with a layer of coke powder, with a thickness of not less than 1cm. The crucible is then placed in a muffle furnace for heat treatment. N2is supplied throughout the heat treatment process, with a flow rate of 5L / min. The heat treatment schedule is as follows: from room temperature to 400°C at a rate of 10°C / min; 2h at 400°C; from 400°C to 970°C at a rate of 10°C / min; 1h at 970°C; cooling with the furnace, and then mechanical screening to obtain the lightweight high-strength shale ceramsite.

[0065] III. Performance index testing.

[0066] The performance index of the lightweight high-strength shale ceramsite prepared in this example is as follows: apparent density 1.52g / cm 3 , bulk density 783kg / m 3 , cylinder compressive strength 12.5MPa, and water absorption 2.1%. The appearance structure and microstructure of the shale ceramsite prepared in this example are shown in Figure 2 , Figure 3 and Figure 4 .

[0067] The shale used in the preparation of the ceramsite in the above examples is mainly sourced from a certain place in Hengyang City, Hunan Province, and is widely available and low in price; the red mud and waste glass powder are mainly sourced from enterprise solid waste; the wood chips, rice husk powder, straw powder, wood ash, paper pulp waste liquid, and molasses are low in price. Overall, the raw materials are low in cost and widely available. At the same time, the pore-forming mechanism of the ceramsite prepared in the examples is mainly due to the pore-forming template of the biomass powder in the ingredients, and by controlling the sintering atmosphere to be reducing or inert, the biomass carbonization product is not ablated, thereby achieving the purpose of regulating the pore structure of the ceramsite at room temperature, and having certain designability. In addition, the waste glass powder in the raw materials can melt at high temperatures and form a coating effect, thereby forming a dense glaze layer on the surface of the carbon particles in the ceramsite, which can further reduce the water absorption of the ceramsite. As can be seen from Figure 2 , Figure 3 and Figure 4 , the shale ceramsite has very small pores, and in Figure 4It can be seen from the microstructure that the surface of the carbon particles is formed with a dense protective layer (white small particle-like morphology in the figure). It can be seen from the performance test results of the ceramsite that the shale ceramsite prepared in the above examples has the advantages of low density, high strength and low water absorption. At the same time, by adding appropriate amounts of waste glass powder, red mud, wood ash, fluorite and other sintering additives in the raw material batching, the sintering temperature of the shale ceramsite can be significantly reduced. The sintering temperature of the ceramsite in the examples can be reduced from the existing sintering temperature of 1200℃ of the shale ceramsite to 900-1000℃, and the energy consumption is significantly reduced.

[0068] In order to make the ordinary skilled in the art more convenient to understand the improvements of the present application relative to the prior art, some drawings and descriptions of the present application have been simplified, and the above examples are the preferred implementation of the present application, in addition to this, the present application can also be implemented in other ways, any obvious replacement within the concept of the present technical solution without departing from the present technical solution is within the protection scope of the present application.

Claims

1. A method for preparing a low sintering temperature, lightweight, high strength shale ceramisite, characterized in that, The method comprises the following steps: (1) forming a raw material by taking shale powder as a main material, biomass powder as a pore-forming template, and one or more of waste glass powder, wood ash, red mud, and fluorite as a sintering aid; (2) uniformly mixing the raw material according to a proportion to obtain a uniformly dispersed composite powder; (3) preparing a ceramsite raw material by using a granulator, drying the ceramsite raw material, and setting a drying system at 105 DEG C for 24 h; loading the dried ceramsite raw material into a high-alumina bauxite kiln, covering the surface of the ceramsite raw material with coke powder, and setting a thickness of the coke powder to be not less than 1 cm; and then placing the kiln in a muffle furnace for heat treatment; during the heat treatment, N2 is supplied at a flow rate of 5 L / min; the heat treatment system is set as follows: increasing the temperature from room temperature to 400 DEG C at a rate of 10 DEG C / min; maintaining the temperature at 400 DEG C for 2 h; increasing the temperature from 400 DEG C to 970 DEG C at a rate of 10 DEG C / min; maintaining the temperature at 970 DEG C for 1 h; cooling the furnace; and then performing mechanical screening to obtain the lightweight high-strength shale ceramsite.

2. The process for the preparation of low sintering temperature, light weight, high strength shale ceramsite as claimed in claim 1, wherein: The particle size of the shale powder is less than 0.045 mm, the particle size of the biomass powder is less than 0.023 mm, and the particle size of the waste glass powder, wood ash, red mud, and fluorite is less than 0.045 mm.

3. The process for the preparation of low sintering temperature, light weight, high strength shale ceramsite as claimed in claim 1, wherein: The biomass powder is one or a combination of sawdust, rice husk powder, and straw powder.

4. The process for the preparation of low sintering temperature, light weight, high strength shale ceramsite as claimed in claim 1, wherein: The particle size of the prepared ceramsite raw material is 3-20 mm.

5. The method of producing low sintering temperature, lightweight, high strength shale ceramsite according to any one of claims 1-4, characterized in that: The mass ratio of the shale powder in the raw material is not less than 65%.

6. The process for the preparation of low sintering temperature, light weight, high strength shale ceramsite according to any one of claims 1-4, characterized by: The mass ratio of the biomass powder in the raw material is 1.5-15%.

7. The method of producing low sintering temperature, lightweight, high strength shale ceramsite according to any one of claims 1-4, characterized in that: The mass ratio of the sintering aid in the raw material is 10-35%, wherein the mass ratio of the waste glass powder is 8-25%, the mass ratio of the wood ash is 0-10%, the mass ratio of the red mud is 0-25%, and the mass ratio of the fluorite is 0-5%.

8. A low sintering temperature, lightweight, high strength shale ceramisite, characterized by: The lightweight high-strength shale ceramsite is prepared by using the method of any one of claims 1-7.

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