Preparation method of low-temperature fast-fired ceramic tile

Abstract

The invention relates to a preparation method of a low-temperature fast-fired ceramic tile. The method comprises the following steps in sequence. Carrying out ball milling on the screened raw materials in a ball mill; sieving and deironing slurry prepared by ball milling; carrying out powder spraying on the slurry subjected to sieving and deironing to prepare green body powder; pressing the green body powder into a green body; the method is characterized in that the fineness of the slurry prepared in the ball milling step is that the slurry accounts for less than 0.8 wt% of the slurry on a 250-mesh screen. The method has the advantages of low firing temperature, short firing time, good product performance and the like.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic tile preparation, in particular to a method for preparing ceramic tiles with low temperature and fast firing. Background Art

[0002] Since the low-temperature fast firing method of ceramic tiles has the advantages of low fuel consumption and high kiln utilization, it has always been the focus of technical improvement of modern ceramic tile enterprises. However, most of the current low-temperature fast firing technical methods of ceramic tiles are achieved by adjusting the chemical composition of the body, such as by adjusting the proportion of high-melting-point oxides such as silicon dioxide and aluminum oxide in the body, or increasing the content of solvents such as potassium oxide and calcium oxide; however, these compounds rarely exist alone in nature, and most of them exist in ores mixed with other compounds. Therefore, ceramic tile enterprises introduce the above components through various ores. Due to the complex composition of the ore and the different composition of ores from different origins, it is difficult for this method to achieve the ideal composition of the body in actual application, and the temperature and time of ceramic tile firing are also difficult to control, so the ideal low-temperature fast firing technical effect cannot be obtained. Summary of the invention

[0003] The purpose of the present invention is to solve the above-mentioned problems and shortcomings, and to provide a method for preparing low-temperature, fast-firing tiles. By adjusting the fineness of the slurry obtained when the raw materials are ball-milled, the firing temperature and firing time of the tiles can be reduced, so that the present invention can greatly reduce the comprehensive energy consumption of the tile production process, thereby significantly reducing production costs.

[0004] The technical solution of the present invention is implemented as follows: a method for preparing low-temperature fast-firing tiles, which comprises the following steps in sequence: raw material screening → ball milling the screened raw materials in a ball mill → sieving the slurry obtained by ball milling to remove iron → spraying the slurry after screening and iron removal to obtain green body powder → pressing the green body powder into a green body → drying the green body → sending the dried green body into a kiln for firing, and its characteristic is that the fineness of the slurry obtained by ball milling is less than 0.8% by weight on a 250-mesh sieve.

[0005] Furthermore, the fineness of the slurry obtained by ball milling is less than 0.5% by weight on a 250-mesh sieve.

[0006] Furthermore, the particle size distribution of the raw material is such that the weight percentage on the 8-mesh sieve is less than 50%; and the ball milling time of the raw material in the ball mill is 11.5 to 14 hours.

[0007] Furthermore, the particle size distribution of the raw material is such that the weight percentage on the 8-mesh sieve is less than 30%; and the ball milling time of the raw material in the ball mill is 11.5 to 13 hours.

[0008] Furthermore, the water weight percentage of the slurry is 33% to 36%, and the flow rate is 35 to 65 seconds.

[0009] Furthermore, the properties of the green body powder are as follows: the water weight percentage is 6% to 7.5%, and the particle gradation is as follows: the weight percentage on the 40-mesh sieve is greater than 68%, and the weight percentage on the 100-mesh sieve is less than 5%.

[0010] Furthermore, the weight percentage of water in the dried green body is less than 0.5%.

[0011] Beneficial effects of the present invention:

[0012] Firstly, the present invention controls the fineness of the slurry obtained by ball milling the raw materials for ceramic tiles to be less than 0.8% by weight on a 250-mesh sieve, thereby making the mineral particles constituting the ceramic tile body smaller. Thus, during the firing process, the contact area between the mineral particles of the ceramic tile body and the external heat energy is increased, thereby accelerating the heating rate of the ceramic tile body, reducing the energy required for the reaction of the single-substance particles, and further effectively reducing the firing temperature and firing time of the ceramic tile body, thereby greatly reducing the energy loss of the ceramic tile product during firing and improving the production efficiency of the kiln.

[0013] Secondly, under the same firing conditions, since the mineral particles that make up the tile body become smaller, the surface and interior of the tile body are heated more evenly, and various physical and chemical reactions change more evenly, making the later stress release of the tile product very uniform and not prone to later reversal. In addition, the compactness and structural uniformity of the particles inside the tile are also better, which makes the water absorption rate of the tile product lower, helping to further prevent the deformation of the tile product.

[0014] In addition, as the firing temperature is reduced, when the mullite produced in the ceramic tile body during the firing process is sufficient, the softening degree of the ceramic tile body is small and the body deformation is also small, so the roller mark produced during the firing process will also be greatly weakened. DETAILED DESCRIPTION

[0015] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is clearly and completely described below in conjunction with specific embodiments of the present invention.

[0016] A method for preparing low-temperature fast-firing tiles, comprising the following steps in sequence: raw material screening → ball milling the screened raw materials in a ball mill → sieving the slurry obtained by ball milling to remove iron → spraying the slurry after screening and iron removal to obtain green body powder → pressing the green body powder into a green body → drying the green body → sending the dried green body into a kiln for firing. In order to achieve the purpose proposed in this application, the fineness of the slurry obtained by ball milling is less than 0.8% by weight on a 250-mesh sieve.

[0017] The specific steps of the present invention are as follows:

[0018] S1: Raw material screening. In order to reduce the ball milling time of the raw materials in the ball mill, improve the efficiency of the ball mill, and reduce the energy consumption of ball milling, the particle gradation of the raw materials is less than 50% by weight on the 8-mesh screen; in order to further reduce the energy consumption of the ball mill and improve the efficiency of ball milling, the particle gradation of the raw materials is further preferably less than 30% by weight on the 8-mesh screen.

[0019] S2: ball milling. In order to ensure that the fineness of the slurry obtained in the ball milling step can meet the requirements, the ball milling time of the raw materials in the ball mill is 11.5 to 14 hours, and the fineness of the obtained slurry is less than 0.8% on a 250-mesh sieve. The fineness of the obtained slurry is further preferably less than 0.5% on a 250-mesh sieve. In order to make the slurry have good fluidity and reduce the energy consumption in the subsequent powder spraying step, and make the slurry easy to atomize and granulate, the weight percentage of water in the slurry is 33% to 36%. The flow rate of the slurry is 40 to 80 seconds. By controlling the flow rate in the slurry, the particle gradation of the green body powder that meets the process requirements can be obtained in the next step of spray drying and dehydration to prepare the green body powder.

[0020] S3: Screening and iron removal. In order to ensure the size and gradation of the particles in the slurry and limit the content of coarse particles in the green body, the slurry obtained by ball milling is passed through an 80-mesh screen to screen out coarse particles and other impurities, and then the iron impurities in the slurry are removed by an iron remover.

[0021] S4: powder spraying, the powder spraying adopts the spray drying dehydration method, the slurry after sieving iron removal is passed through a drying tower and the water is evaporated at high temperature to form a green body powder; the moisture content of the green body powder is 6% to 7.5%, and the particle gradation is: the weight percentage on the 40-mesh screen is greater than 68%, and the weight percentage under the 100-mesh screen is less than 5%; the green body powder with a content of 6% to 7.5% has good fluidity and forming performance. When the green body is pressed, the green body powder can quickly fill the mold cavity of the press, which is conducive to obtaining a green body with a higher density; through the above-mentioned particle grading, the ratio of coarse particles larger than 40 mesh to fine particles smaller than 40 mesh in the green body powder is about 2:1. Due to a certain proportion of fine particles, the packing density of the green body powder is relatively large, thereby being able to reduce the porosity in the green body, making the pressing The density and mechanical strength of the green body after molding are also greater; and because the proportion of fine particles is less than that of coarse particles, especially the proportion of fine particles under the 100-mesh sieve is strictly controlled, the fluidity of the green body powder is also better. When the green body powder is pressed, the green body powder can quickly fill the mold cavity of the press, and the fine particles are embedded in the coarse particles, so that the pressed green body has the advantages of uniform structure and high density, which makes the shrinkage rate of the green body lower, which can not only effectively prevent the green body from deformation, cracking and other adverse conditions during the drying process, but also the volume change of the green body when heated during the firing process is also small, thereby speeding up the heating rate of the kiln and helping to achieve rapid firing of tiles; in addition, due to the uniform structure and high density of the green body, the green body is not easy to deform when fired at high temperature, which helps to reduce the stick mark and improve the quality of the tile.

[0022] S5: green body forming, the green body powder is pressed into a green body by a press.

[0023] S6: Drying, drying and dehydrating the green body in a drying kiln. The moisture content of the green body after drying is ≤0.5. In this way, due to the low water content of the green body, during the firing stage, not only can the cracking of the green body caused by water evaporation be reduced, but also the heat consumed by water evaporation can be effectively reduced, thereby greatly improving the heating rate, which is conducive to the rapid firing of tiles; the drying temperature curve of the green body during drying is: the heating time in the front stage is 15 to 20 minutes, from room temperature to 240°C; then enters the insulation stage, the temperature is controlled in the range of 240 to 210°C, and the insulation time is 15 to 20 minutes; then enters the cooling stage, and the temperature drops from the insulation temperature to 150°C within 10 to 15 minutes. Since the green body is not prone to deformation, cracking and other adverse conditions during the drying process, the drying cycle of the present invention can be shortened to less than 1 hour, which is much shorter than the conventional drying process time, thereby greatly improving the processing capacity of the drying device.

[0024] S7: sending the dried green body into a kiln for firing, the firing temperature is 1150-1210°C, and the firing time is 40-65 minutes; the preferred firing temperature curve is: rising from room temperature to 650°C, the heating time is 5-7min; then entering the oxidation stage, rising from 650 to 1100°C, the oxidation time is 5-7min; further heating, from 1100°C to the firing temperature, the heating time is 8-16min; then entering the insulation stage, insulation within the firing temperature range for 15-20min; after the insulation is completed, starting to cool down, from the firing temperature to room temperature, the cooling time is 10-15min; in this way, by controlling the residence time of the green body in the high temperature stage, the green body softening can be avoided, thereby reducing the stick mark.

[0025] S8: Polish the fired ceramic tile products, and put them into storage in grades.

[0026] The technical points and technical effects of the present invention are further described below through specific examples and comparative examples. For ease of comparison, the same green body formula is used in all embodiments of the present invention, and the green body weight formula is as follows: 8 parts of quartz stone, 12 parts of kaolin, 53 parts of feldspar, and 27 parts of clay.

[0027] Embodiment 1:

[0028] In Example 1, the particle grading of the raw materials requires that the content on the 8-mesh sieve is less than 30%; the ball milling time is 11.5 hours, and the fineness of the slurry obtained by ball milling is: less than 0.8% on the 250-mesh sieve, specifically 0.6% to 0.8%, the water content in the slurry is 33% to 36%, and the flow rate of the slurry is 40 to 80 seconds; the moisture content in the obtained green body powder is 6% to 7.5%, and the particle grading of the powder is >68% on the 40-mesh sieve and <5% under the 100-mesh sieve; the method parameters of the sintering step are: sintering temperature 1180 to 1210°C, sintering time 60 to 65 minutes.

[0029] Embodiment 2:

[0030] In Example 2, the particle grading of the raw materials requires that the content on the 8-mesh sieve is less than 50%; the ball milling time is 14 hours, and the fineness of the slurry obtained by ball milling is: less than 0.8% on the 250-mesh sieve, specifically 0.6% to 0.8%, the water content in the slurry is 33% to 36%, and the flow rate of the slurry is 40 to 80 seconds; the moisture content in the obtained green body powder is 6% to 7.5%, and the particle grading of the powder is >68% on the 40-mesh sieve and <5% under the 100-mesh sieve; the method parameters of the sintering step are: sintering temperature 1180 to 1210°C, sintering time 60 to 65 minutes.

[0031] Embodiment three:

[0032] In Example 3, the particle grading of the raw materials requires that the content on the 8-mesh sieve is less than 30%; the ball milling time is 13 hours, and the fineness of the slurry obtained by ball milling is: the weight percentage on the 250-mesh sieve is less than 0.5%, the water content in the slurry is 33% to 36%, and the flow rate of the slurry is 40 to 80 seconds; the moisture content in the obtained green body powder is 6% to 7.5%, and the particle grading of the powder is >68% on the 40-mesh sieve and <5% under the 100-mesh sieve; the method parameters of the sintering step are: sintering temperature 1150 to 1170°C, sintering time 40 to 55 minutes.

[0033] Comparative Example:

[0034] This embodiment is a comparative embodiment. The particle gradation of the raw materials requires that the content on the 8-mesh sieve is less than 30%; the ball milling time is 10.5h, and the fineness of the slurry obtained by ball milling is controlled as commonly used in the existing tile production process: the weight percentage on the 250-mesh sieve is less than 1.0%, specifically 0.8% to 1.0%, the water content in the slurry is 33% to 36%, and the flow rate of the slurry is 40 to 80 seconds; the moisture content in the obtained green body powder is 6% to 7.5%, and the particle gradation of the powder is >68% on the 40-mesh sieve and <5% under the 100-mesh sieve; the method parameters of the firing step are: firing temperature 1220 to 1250°C, firing time 70 to 80min.

[0035] The ceramic tile products prepared in the above-mentioned embodiments 1 to 3 and the comparative embodiment were tested for roller printing, water absorption rate, and late reversion probability, and the energy consumption of each embodiment was calculated. The process parameters of the above-mentioned embodiments and the performance of the ceramic tile products were summarized as shown in the following table:

[0036]

[0037] By comparing the embodiment with embodiments one to three, it can be seen that the comprehensive energy consumption of the product of the comparative embodiment is much higher than that of the other three groups of embodiments. It can be seen that by controlling the fineness of the slurry after ball milling, not only the energy consumption of the tile production equipment can be effectively reduced, but also the quality of the tile products can be improved, achieving multiple goals at one stroke.

[0038] Under the same raw material conditions, after the slurry fineness after ball milling is reduced from "less than 1.0%" to "less than 0.8%", the comprehensive energy consumption is reduced from 6.2kg standard coal / m 2 Reduced to 5.8kg standard coal / m 2 , energy consumption reduced by 0.4kg standard coal / m 2 If calculated based on the coal price of 1,140 yuan / t, the cost can be reduced by 0.45 yuan / ㎡.

[0039] Comparing Example 1 with Example 2, the slurry fineness after ball milling is the same for both, and the properties of the obtained powder are also the same. Under the same firing conditions, the performance of the tile products produced by the two embodiments, such as roller printing, water absorption rate, and late reversion probability, are almost the same; however, since the raw material particles of Example 2 are coarser, the ball milling step takes more time, that is, it consumes more electricity and time, and the comprehensive energy consumption of the product increases by 0.1kg standard coal / ㎡ accordingly. If calculated according to the coal price of 1140 yuan / t, the cost increases by 0.11 yuan / ㎡. It can be seen that the appropriate control of the particle gradation of the raw materials can not only reduce the ball milling time and improve the effect of the ball mill, but also effectively reduce energy consumption, achieving multiple goals at one stroke. Of course, the smaller the particles of the raw materials, the higher their price. This application comprehensively considers the raw material price and the comprehensive energy consumption of the product, and preferably the particle gradation of the raw materials is less than 30% on the 8-mesh sieve.

[0040] Comparing Example 1 with Example 3, the particle grading of the raw materials is the same, and the content on the 8-mesh sieve is less than 30%, but the ball milling time is increased from 11.5h to 13h, and the fineness of the obtained slurry (content on the 250-mesh sieve) is increased from less than 0.8% to less than 0.5%. Although the energy consumption is increased during ball milling, the firing temperature is reduced from 1180-1210°C to 1150-1170°C, the average firing temperature is reduced by about 30°C, and the firing time is reduced from 60-65min to 40-55min, thereby reducing the comprehensive energy consumption of the product from 5.8kg standard coal / m2 to 5.44kg standard coal / m2. If calculated based on the coal price of 1140 yuan / t, the cost can be reduced by 0.41 yuan / m2, thereby achieving the purpose of energy conservation and emission reduction and reducing production costs. From the performance of the ceramic tile products, it can be seen that the roller mark is reduced from the original 0.25-0.4mm to 0.15-0.25mm, the roller mark depth is reduced by about 0.1mm, the water absorption rate is reduced from 0.04% to 0.025%, and the probability of later reversion is reduced from 5% to 1%. In this way, not only the appearance of the ceramic tile products is greatly improved, but also the probability of ceramic tile deformation and falling off in the later stage can be greatly reduced, so that the ceramic tile products have better quality and better user reputation. Therefore, the preferred fineness of the slurry after ball milling in this application is less than 0.5% on the 250 mesh screen.

[0041] By comparing Example 1 with Example 3, it can be seen that the slurry fineness is a key factor in determining the performance of ceramic tile products. The finer the slurry fineness, the smaller the particles that constitute the body. In this way, during the firing process, the body particles are heated faster, and the time and energy required for their reaction are less, thereby effectively reducing the firing temperature and firing time of the ceramic tile body. Moreover, under the same firing conditions, the particles on the surface and inside of the ceramic tile body are heated more evenly, and various physical and chemical reactions change more evenly accordingly, so that the later stress release of the ceramic tile product is very uniform, and it is not easy to produce later reversion. In addition, the compactness and structural uniformity of the particles inside the ceramic tile are very good, so that the water absorption rate of the ceramic tile product is low.

[0042] In addition, due to the lowering of the firing temperature, when the mullite produced by the ceramic tile body during the firing process is sufficient, the softening degree of the ceramic tile body is relatively small, and therefore the roller mark produced during the firing process will also be greatly weakened; the method for adjusting the roller mark in the current prior art is to slow down the kiln speed and reduce the firing temperature; however, when the particle size of the slurry is large, lowering the firing temperature will cause the various physical and chemical reactions on the surface and inside of the body to be at different levels, resulting in uneven stress release of the ceramic tile product in the later stage, which is prone to later reversal. Therefore, compared with the prior art, the present application can not only achieve low-temperature and fast firing of ceramic tiles, save energy and reduce emissions, but also greatly improve the performance of ceramic tile products.

[0043] In summary, the present application controls the process parameters of the slurry obtained after ball milling and the green body powder, so that the green body of the present application can be quickly fired under low temperature conditions, which can not only reduce the energy consumption of the production device, but also greatly alleviate the stick marks on the surface of the tile, and greatly reduce the water absorption rate and the probability of later reversion of the tile products, thereby greatly improving the quality of the tile. In addition, the control of the raw material particle grading can also reduce the energy consumption of the raw material during ball milling, and effectively improve the processing capacity of the ball milling device, thereby helping to improve production efficiency and reduce production costs.

Claims

1. A method for preparing low-temperature fast-firing ceramic tiles, comprising the following steps in sequence: raw material screening → ball milling the screened raw materials in a ball mill → sieving the slurry obtained by ball milling to remove iron → spraying the slurry after sieving and removing iron to obtain green body powder → pressing the green body powder into a green body → drying the green body → sending the dried green body into a kiln for firing, characterized in that: The fineness of the slurry obtained by ball milling is less than 0.8% by weight on a 250-mesh screen.

2. The method for preparing low-temperature fast-firing tiles according to claim 1, characterized in that: The fineness of the slurry obtained by ball milling is less than 0.5% by weight on a 250-mesh screen.

3. The method for preparing low-temperature fast-firing tiles according to claim 1 or 2, characterized in that: The particle size distribution of the raw material is such that the weight percentage of the raw material on the 8-mesh screen is less than 50%; the ball milling time of the raw material in the ball mill is 11.5 to 14 hours.

4. The method for preparing low-temperature fast-firing tiles according to claim 1 or 2, characterized in that: The particle size distribution of the raw material is such that the weight percentage of the raw material on the 8-mesh screen is less than 30%; the ball milling time of the raw material in the ball mill is 11.5 to 13 hours.

5. The method for preparing low-temperature fast-firing tiles according to claim 1 or 2, characterized in that: The water weight percentage of the slurry is 33% to 36%, and the flow rate is 35 to 65 seconds.

6. The method for preparing low-temperature fast-firing tiles according to claim 1 or 2, characterized in that: The particle size distribution of the green body powder is as follows: the weight percentage on the 40-mesh screen is greater than 68%, and the weight percentage on the 100-mesh screen is less than 5%.

7. The method for preparing low-temperature fast-firing tiles according to claim 1, characterized in that: The weight percentage of moisture in the dried green body is less than 0.5%.

8. The method for preparing low-temperature fast-firing tiles according to claim 7, characterized in that: The drying temperature curve of the green body during drying is as follows: the heating time in the first stage is 15 to 20 minutes, from room temperature to 240°C; then it enters the insulation stage, the temperature is controlled in the range of 240 to 210°C, and the insulation time is 15 to 20 minutes; then it enters the cooling stage, and the insulation temperature drops to 150°C within 10 to 15 minutes.

9. The method for preparing low-temperature fast-firing tiles according to claim 1 or 2, characterized in that: The firing temperature in the firing kiln is 1150-1210° C. and the firing time is 40-65 minutes.

10. The method for preparing low-temperature fast-firing tiles according to claim 9, characterized in that: The firing temperature curve in the firing kiln is: from room temperature to 650°C, the heating time is 5 to 7 minutes; then enter the oxidation stage, from 650 to 1100°C, the oxidation time is 5 to 7 minutes; further increase the temperature from 1100°C to the firing temperature, the heating time is 8 to 16 minutes; then enter the insulation stage, and keep the temperature within the firing temperature range for 15 to 20 minutes; After the insulation is completed, the temperature begins to drop from the firing temperature to room temperature, and the cooling time is 10 to 15 minutes.

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