A multi-thickness glazed tile mixed firing process

Abstract

The present application relates to the technical field of building ceramics, and particularly relates to a mixed firing process for glazed tiles with multiple thicknesses, comprising: A, preparing small-thickness slurry, medium-thickness slurry and large-thickness slurry; the small-thickness slurry is sieved through a 325-mesh sieve, and the sieve residue is 2.7-3.2%; the medium-thickness slurry is sieved through a 325-mesh sieve, and the sieve residue is 1.8-2.3%; the large-thickness slurry is sieved through a 325-mesh sieve, and the sieve residue is 1.4-1.9%. B, preparing small-thickness powder, medium-thickness powder and large-thickness powder; C, preparing small-thickness body layer, medium-thickness body layer and large-thickness body layer; D, preparing at least one of small-thickness glazed body, medium-thickness glazed body and large-thickness glazed body; E, sequentially conveying multiple glazed bodies to the brick feeding position of a large-capacity kiln for firing; the mixed firing process for glazed tiles with multiple thicknesses can realize low-temperature fast firing of full-polished glazed tiles with different thicknesses in the same kiln, and the fired tile products not only meet the physical and chemical properties of full-polished glaze, but also balance the tile shape and body quality of products with different thicknesses.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building ceramics, and in particular to a mixed firing process for glazed tiles of multiple thicknesses. BACKGROUND

[0002] In order to reduce unit cost and improve market competitiveness through economies of scale, and to adapt to the production needs of the industry at scale, existing building ceramic production enterprises generally have large-capacity production lines with a daily capacity of up to 40,000 m2, and even up to 60,000 m2. 2 The core equipment of a large-capacity production line is a super-wide body kiln (hereinafter referred to as a "large-capacity kiln"), which typically has three brick entry positions corresponding to three glaze lines for improved production efficiency and output.

[0003] Generally, a large-capacity kiln can only fire one type of ceramic tile at a time, but as market competition intensifies, large orders for single product categories are becoming less common, and small orders for products are becoming more common. There are differences in the requirements of each product, such as body whiteness, body water absorption, body powder granulation process, size, thickness, glaze effect, and product pattern depth.

[0004] Currently, large-capacity kilns are difficult to adapt to the production of small orders, resulting in the shutdown of many large-capacity kiln production lines. The main reasons are as follows:

[0005] First, the number of small orders is small, leading to frequent changes in production and high production losses. It also causes the kiln to be empty, affecting the stability of the firing curve in the kiln and thus the quality of the product.

[0006] Second, the process of different products differs greatly, making it difficult for the kiln to match multiple products and affecting product quality.

[0007] Therefore, how to achieve mixed firing of multiple ceramic tile products in a large-capacity kiln is a difficult problem in the current market situation for the building ceramics industry.

[0008] In the market, the main body thickness of ceramic tiles, as the mainstream product, is mainly divided into three types: large thickness (mainly 10mm thick), medium thickness (mainly 9mm thick), and small thickness (mainly 7.4mm thick). Mixing and firing of ceramic tile products of different thicknesses may have the following problems:

[0009] First, deformation or cracking. Different thicknesses of brick bodies are unevenly heated during firing, with thicker brick bodies having slower internal heat conduction and longer sintering times, while thinner brick bodies are prone to stress concentration due to rapid heating or cooling, resulting in black core, insufficient vitrification, and other issues in thicker brick bodies, and over-firing, excessive softening, deformation, or cracking in thinner brick bodies.

[0010] Second, the firing cycle conflicts, the firing time of thinner bricks is short, and the firing time of thicker bricks needs to be extended, which is difficult to balance in mixed firing, and may reduce production efficiency or sacrifice part of the product quality.

[0011] Third, energy consumption increases. In order to meet the firing needs of thicker bricks, the firing cycle needs to be extended, resulting in increased fuel consumption; if multiple thicknesses of ceramic tile products are forced to be fired simultaneously, thinner bricks may be over-fired, causing energy waste.

[0012] Fourth, the actual performance of the ceramic tile product may differ greatly from the target performance, for example, the water absorption of thicker bricks may be higher (due to insufficient sintering), and the mechanical strength of thinner bricks may be insufficient (due to micro-cracks caused by over-firing).

[0013] For the above reasons, mixed firing of different thicknesses of ceramic tile products is not valued in the industry, but as the real estate market declines, the number of orders for the same thickness of products decreases, and switching between different thicknesses becomes frequent. Therefore, on the basis of not affecting the performance, efficiency, energy consumption, etc. of the product, how to achieve mixed firing of different thicknesses of products is an industry problem to be solved. SUMMARY

[0014] The purpose of the present application is to provide a multi-thickness glazed tile mixed firing process that can achieve low-temperature fast firing of full-body glazed ceramic tiles of different thicknesses in the same kiln, and the fired ceramic tile products not only meet the physical and chemical properties of full-body glaze, but also balance the brick shape and body quality of full-body glazed ceramic tile products corresponding to different thicknesses, overcoming the shortcomings of the prior art.

[0015] To achieve this purpose, the present application adopts the following technical solutions:

[0016] A multi-thickness glazed tile mixed firing process is suitable for a large-capacity kiln, and the large-capacity kiln is provided with three brick feeding positions in the width direction, and the mixed firing process comprises the following steps:

[0017] A. Mix the raw materials of low-hygroscopic powder, ball mill with water and adjust the ball mill fineness to obtain small thickness slurry, medium thickness slurry and large thickness slurry, respectively;

[0018] B. Spray the small thickness slurry, medium thickness slurry and large thickness slurry into the spray granulation tower respectively, and obtain small thickness powder, medium thickness powder and large thickness powder in turn after spray granulation;

[0019] C. After pressing the small thickness powder, medium thickness powder and large thickness powder respectively, small thickness body layer, medium thickness body layer and large thickness body layer are obtained in turn;

[0020] D. preparing a plurality of glaze blanks, and the glaze blanks are at least one of small-thickness glaze blanks, medium-thickness glaze blanks and large-thickness glaze blanks;

[0021] E. sequentially conveying the plurality of glaze blanks to the brick feeding position of the large-capacity kiln, and firing under the condition of a firing temperature ≤ 1100 ℃ and a firing period ≤ 30 min;

[0022] In step A, according to the mass percentage, the small-thickness slurry is passed through a 325 mesh sieve, and the residue is 2.7-3.2%; the medium-thickness slurry is passed through a 325 mesh sieve, and the residue is 1.8-2.3%; and the large-thickness slurry is passed through a 325 mesh sieve, and the residue is 1.4-1.9%;

[0023] In step C, the thickness of the small-thickness body layer is 6.8-8.6 mm, the thickness of the medium-thickness body layer is > 8.6 mm and ≤ 9.4 mm, and the thickness of the large-thickness body layer is > 9.4 mm and ≤ 12 mm;

[0024] In step D, the small-thickness glaze blank comprises the small-thickness body layer, and a medium-swelling surface glaze, color ink and full-polish glaze are sequentially applied from bottom to top on the top surface of the small-thickness body layer; wherein the application amount of the medium-swelling surface glaze is 500-560 g / m 2 ; the medium-thickness glaze blank comprises the medium-thickness body layer, and a medium-swelling surface glaze, color ink and full-polish glaze are sequentially applied from bottom to top on the top surface of the medium-thickness body layer; wherein the application amount of the medium-swelling surface glaze is 420-480 g / m 2 ; and the large-thickness glaze blank comprises the large-thickness body layer, and a balance surface glaze, color ink and full-polish glaze are sequentially applied from bottom to top on the top surface of the large-thickness body layer; wherein the balance surface glaze is a mixture of a medium-swelling surface glaze and a low-swelling surface glaze in a mass ratio of 1:1, and the application amount of the balance surface glaze is 420-480 g / m 2 ;

[0025] In step E, the firing curve of the large-capacity kiln comprises a preheating section, a preheating section, a medium temperature section, a high temperature section, a rapid cooling section and a slow cooling section: the surface temperature of the preheating section rises from room temperature to 950℃, the bottom temperature rises from room temperature to 1100℃, and the time consumption is 3.5-3.7min; the surface temperature of the preheating section rises from 950℃ to 1110℃, the bottom temperature drops from 1100℃ to 1060℃, and the time consumption is 2-2.2min; the surface temperature of the medium temperature section rises from 1110℃ to 1203℃, the bottom temperature rises from 1060℃ to 1226℃, and the time consumption is 7.7-7.9min; the surface temperature of the high temperature section is 1203℃, the bottom temperature is 1226℃, and the time consumption is 4.3-4.5min; the surface temperature of the rapid cooling section drops from 1203℃ to 570℃, the bottom temperature drops from 1226℃ to 300℃, and the time consumption is 4.7-4.9min; the surface temperature of the slow cooling section drops from 570℃ to room temperature, the bottom temperature drops from 300℃ to room temperature, and the time consumption is 6.4-6.6min.

[0026] Preferably, step A further comprises adding a green body reinforcing agent in an amount of 0.1-0.2% of the dry raw material, based on the mass ratio;

[0027] In step C, the pressure of the pressing is 38-42MPa / m 2 .

[0028] Preferably, after firing in step E, the water absorption of the small-thickness green body layer, the medium-thickness green body layer and the large-thickness green body layer is ≤0.5%, based on the mass percentage;

[0029] The chemical composition of the low-hygroscopic powder comprises Al2O3, CaO, MgO, K2O and Na2O, and the content of Al2O3 in the low-hygroscopic powder is 17.2-18.2%, the total content of CaO, MgO, K2O and Na2O is 5.6-6.6%, the content of CaO is ≥0.8%, the content of MgO is ≥1.8%, the content of K2O is ≥1.5%, and the content of Na2O is ≥1.5%, based on the mass percentage.

[0030] Preferably, the chemical composition of the low-hygroscopic powder comprises SiO266.4-67.5%, Al2O317.2-18.2%, Fe2O31.6-2.7%, TiO20.3-0.5%, CaO 0.8-1.2%, MgO 1.8-2.3%, K2O 1.5-1.6%, Na2O 1.5-1.8% and loss on ignition 4.8-5.5%, based on the mass percentage.

[0031] Preferably, the small-thickness green body layer, the medium-thickness green body layer and the large-thickness green body layer are all 800mm×800mm in size, and in the large-capacity kiln, the front side edges of the small-thickness green body layer, the medium-thickness green body layer and the large-thickness green body layer along the conveying direction form an angle one with the width direction of the large-capacity kiln, and the angle one is 5-11°.

[0032] Preferably, the small-thickness green body layer, the medium-thickness green body layer and the large-thickness green body layer are all 750mm×1500mm in size, and in the large-capacity kiln, the short side edges of the small-thickness green body layer, the medium-thickness green body layer and the large-thickness green body layer form an angle two with the width direction of the large-capacity kiln, and the angle two is 7-13°.

[0033] Preferably, the expansion coefficient of the low-expansion glaze is (6.6-6.8)×10 -6 / ℃, and according to mass fraction, the raw materials of the low-expansion glaze include 36-40 parts of sodium feldspar, 9-11 parts of kaolin, 2-4 parts of quartz, 7-9 parts of nepheline, 10-14 parts of alumina, 10-14 parts of potassium feldspar, 14-16 parts of calcined clay, 1-3 parts of calcined talc and 10-14 parts of zirconium silicate;

[0034] The expansion coefficient of the medium-expansion glaze is (7.3-7.5)×10 -6 / ℃, and according to mass fraction, the raw materials of the medium-expansion glaze include 38-42 parts of sodium feldspar, 9-11 parts of kaolin, 4-6 parts of quartz, 9-11 parts of nepheline, 12-16 parts of alumina, 10-14 parts of potassium feldspar, 5-7 parts of calcined clay, 2-4 parts of calcined talc and 10-14 parts of zirconium silicate.

[0035] Preferably, the full-polish glaze of the small-thickness glaze body, the full-polish glaze of the medium-thickness glaze body and the full-polish glaze of the large-thickness glaze body are the same;

[0036] The raw materials of the full-polish glaze include sodium feldspar, kaolin, calcined clay, dolomite, quartz, calcite, alumina, zinc oxide and strontium carbonate;

[0037] The silicon-aluminum ratio of the full-polish glaze is 3.0-3.2, and according to mass percentage, the content of Na2O in the full-polish glaze is 4.2-5.2%, and the content of SrO is 3.3-4.3%.

[0038] Preferably, the chemical composition of the full polishing glaze includes, in terms of mass percentage, SiO2 45.0-49.0%, Al2O3 14.7-15.6%, Fe2O3 0.1-0.2%, TiO2 0.05-0.1%, CaO 8.5-9.5%, MgO 2.5-3.5%, K2O 0.1-0.3%, Na2O 4.2-5.2%, ZnO 3.4-4.4%, SrO 3.3-4.3%, and loss on ignition 8.0-12.0%.

[0039] Preferably, the glazing amount of the full polishing glaze is 420-480 g / m 2 ;

[0040] The inkjet amount of the color ink of the small-thickness glaze body, the color ink of the medium-thickness glaze body, and the color ink of the large-thickness glaze body is 4.8-9.6 g / m 2 .

[0041] The technical solution provided by the present application can include the following beneficial effects:

[0042] The multi-thickness glazed tile mixed firing process provided by the present application can realize low-temperature fast firing of full polishing glaze ceramic tiles of different thicknesses in the same kiln, and the fired ceramic tile products not only meet the physical and chemical properties of the full polishing glaze, but also balance the tile shape and body quality of the full polishing glaze ceramic tile products corresponding to different thicknesses, overcoming the deficiencies in the prior art. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is a laying-out schematic view of the 800-specification glaze body in the multi-thickness glazed tile mixed firing process of the present application.

[0044] Figure 2 is a laying-out schematic view of the 715-specification glaze body in the multi-thickness glazed tile mixed firing process of the present application. DETAILED DESCRIPTION

[0045] The technical solution provided by the present application is a multi-thickness glazed tile mixed firing process, which is suitable for a large-capacity kiln, and the large-capacity kiln is provided with three tile feeding positions in the width direction, and the mixed firing process comprises the following steps:

[0046] A. The raw materials of the low-hygroscopicity method powder are mixed, water is added for ball milling, and the ball milling fineness is adjusted to obtain small-thickness slurry, medium-thickness slurry, and large-thickness slurry, respectively;

[0047] B. The small-thickness slurry, the medium-thickness slurry, and the large-thickness slurry are sprayed into a spray granulation tower to obtain small-thickness powder, medium-thickness powder, and large-thickness powder, respectively, through spray granulation;

[0048] C, respectively, the small thickness powder, medium thickness powder and large thickness powder are pressed to obtain small thickness body layer, medium thickness body layer and large thickness body layer in turn;

[0049] D, a plurality of glaze blanks are prepared, and the glaze blanks are at least one of small thickness glaze blank, medium thickness glaze blank and large thickness glaze blank;

[0050] E, the plurality of glaze blanks are sequentially transported to the brick feeding position of the large capacity kiln, and are fired under the condition that the firing temperature is ≤1100℃ and the firing period is ≤30min;

[0051] In step A, according to the mass percentage, the small thickness slurry is passed through a 325 mesh screen, and the residue is 2.7-3.2%; the medium thickness slurry is passed through a 325 mesh screen, and the residue is 1.8-2.3%; the large thickness slurry is passed through a 325 mesh screen, and the residue is 1.4-1.9%;

[0052] In step C, the thickness of the small thickness body layer is 6.8-8.6mm, the thickness of the medium thickness body layer is >8.6mm and ≤9.4mm, and the thickness of the large thickness body layer is >9.4mm and ≤12mm;

[0053] In step D, the small thickness glaze blank includes the small thickness body layer, and the medium swelling surface glaze, color ink and full polishing glaze are sequentially applied from bottom to top on the top surface of the small thickness body layer; wherein the application amount of the medium swelling surface glaze is 500-560g / m 2 ; the medium thickness glaze blank includes the medium thickness body layer, and the medium swelling surface glaze, color ink and full polishing glaze are sequentially applied from bottom to top on the top surface of the medium thickness body layer; wherein the application amount of the medium swelling surface glaze is 420-480g / m 2 ; the large thickness glaze blank includes the large thickness body layer, and the balance surface glaze, color ink and full polishing glaze are sequentially applied from bottom to top on the top surface of the large thickness body layer; wherein the balance surface glaze is mixed by the medium swelling surface glaze and the low swelling surface glaze in a mass ratio of 1:1, and the application amount of the balance surface glaze is 420-480g / m 2 ;

[0054] In step E, the firing curve of the large-capacity kiln comprises a preheating section, a preheating section, a medium temperature section, a high temperature section, a rapid cooling section and a slow cooling section: the surface temperature of the preheating section rises from room temperature to 950℃, the bottom temperature rises from room temperature to 1100℃, and the time consumption is 3.5-3.7min; the surface temperature of the preheating section rises from 950℃ to 1110℃, the bottom temperature drops from 1100℃ to 1060℃, and the time consumption is 2-2.2min; the surface temperature of the medium temperature section rises from 1110℃ to 1203℃, the bottom temperature rises from 1060℃ to 1226℃, and the time consumption is 7.7-7.9min; the surface temperature of the high temperature section is 1203℃, the bottom temperature is 1226℃, and the time consumption is 4.3-4.5min; the surface temperature of the rapid cooling section drops from 1203℃ to 570℃, the bottom temperature drops from 1226℃ to 300℃, and the time consumption is 4.7-4.9min; the surface temperature of the slow cooling section drops from 570℃ to room temperature, the bottom temperature drops from 300℃ to room temperature, and the time consumption is 6.4-6.6min.

[0055] In order to realize the mixed firing of full polishing glaze ceramic tiles with different thicknesses in the same kiln, the technical scheme proposes a multi-thickness glaze tile mixed firing process, which on the one hand realizes low temperature fast firing (this scheme refers to firing temperature ≤1100℃, firing period ≤30min), which is beneficial to reduce energy consumption and reduce carbon emissions, on the other hand, it can balance the tile shape and body quality of the three kinds of ceramic tile products under the premise of ensuring the realization of the physical and chemical properties of full polishing glaze. It should be noted that the firing temperature of this scheme is measured by the British Porex temperature ring, which reflects the equivalent temperature corresponding to the comprehensive thermal effect experienced by the temperature ring at the placement position during the actual firing process.

[0056] Since the full polishing glaze is the surface layer of the glaze tile, it generally needs to consider gloss, wear resistance, acid and alkali resistance, color performance and stain resistance and other physical and chemical properties. Therefore, in order to reduce the design difficulty of glaze, at the same time solve the technical problem that ceramic tile products with different body thicknesses are difficult to mix firing, balance the tile shape and body quality of full polishing glaze ceramic tile products corresponding to different thicknesses, this scheme first adjusts the surface temperature curve and bottom temperature curve of the kiln, so that the obtained firing curve can match the firing characteristics of three thicknesses of body at the same time, and ensure the quality of the fired body.

[0057] Then, this scheme also introduces face glaze with different expansion coefficients to match the above three kinds of glaze body with different thicknesses, respectively, to make up for the tile shape of the three kinds of full polishing glaze ceramic tile products with different thicknesses, to adapt to the firing in the same kiln environment, to ensure that the out-of-kiln deformation difference is small, and to meet the quality standards. Further, due to the slight tendency of convex deformation of thin brick products with small thickness body layer due to thickness factors, the glazing amount of medium expansion face glaze needs to be increased to 500-560g / m 2 , and the concave deformation tendency generated by the shrinkage characteristics of the glaze layer is used for accurate compensation, so as to realize the comprehensive regulation of the flatness of the product.

[0058] In addition, in view of the difference in sintering characteristics of different thickness products, the present scheme also realizes stable production under uniform sintering conditions by precisely regulating the body fineness. Specifically, for the large thickness body layer, an extremely small fineness with a sieve residue of 1.4-1.9wt% is adopted to enhance the sintering activity and compensate for the heat transfer resistance caused by the increase in thickness; the large thickness body layer is matched with a standard fineness with a sieve residue of 1.8-2.3wt% to maintain a moderate sintering rate; and the small thickness body layer of thin brick product adopts a large fineness with a sieve residue of 2.7-3.2wt% to appropriately reduce the sintering activity to avoid overfiring deformation. This gradient fineness regulation strategy is essentially based on the "thickness-fineness" reverse compensation mechanism: the greater the thickness, the smaller the fineness is adjusted to strengthen the sintering; the smaller the thickness, the larger the fineness is adjusted to inhibit overfiring, so that different thickness bodies can all obtain ideal sintering effect under the same sintering system, realizing flexible manufacturing of the production line.

[0059] It should be further pointed out that the mixed firing process of the present scheme refers to that the glaze bodies of multiple ceramic tile products can be fired in the same kiln in the same batch, and the placement position of the glaze bodies in the large-capacity kiln in step E is not limited. Specifically, small thickness glaze bodies, medium thickness glaze bodies and large thickness glaze bodies can be placed in three brick feeding positions in the same width direction of the large-capacity kiln, and the three brick feeding positions in other width directions are the same, i.e. the placement mode of the embodiment; or three small thickness glaze bodies are placed in three brick feeding positions in the same width direction of the large-capacity kiln, then three medium thickness glaze bodies are placed in three brick feeding positions in the next width direction, and then three large thickness glaze bodies are placed in three brick feeding positions in the next width direction, and so on; or two small thickness glaze bodies and one medium thickness glaze body are placed in three brick feeding positions in the same width direction of the large-capacity kiln, then one medium thickness glaze body and two large thickness glaze bodies are placed in three brick feeding positions in the next width direction, and so on.

[0060] Further, step A further comprises adding a body enhancer accounting for 0.1-0.2% of the dry raw materials to the small thickness slurry according to the mass ratio;

[0061] In step C, the pressure of the pressing is 38-42MPa / m 2 .

[0062] In addition, in order to balance the strength of ceramic tiles of different thicknesses, the present scheme also specially adds a body enhancer for improving the strength of the body to the thin brick body, and at the same time, the pressure of the forming press during pressing is uniformly kept at 38-42MPa / m 2 , so as to ensure the strength requirements of brick bodies of different thicknesses.

[0063] Preferably, the body reinforcing agent used in the present solution can be purchased from Foshan Yuanda Glaze Co., Ltd.

[0064] Further, after the firing of step E, the water absorption of the small-thickness body layer, the medium-thickness body layer and the large-thickness body layer is ≤0.5% according to mass percentage.

[0065] The chemical composition of the low-hygroscopic powder includes Al2O3, CaO, MgO, K2O and Na2O, and according to mass percentage, the content of Al2O3 in the low-hygroscopic powder is 17.2-18.2%, the total content of CaO, MgO, K2O and Na2O is 5.6-6.6%, the content of CaO is ≥0.8%, the content of MgO is ≥1.8%, the content of K2O is ≥1.5%, and the content of Na2O is ≥1.5%.

[0066] In the prior art, after the body is softened at the high-temperature section of the kiln, it is prone to deformation under the action of its own gravity and the friction of the roller bar due to insufficient skeleton strength, thereby forming roller bar marks. In particular, when producing products with a water absorption of <0.1%, the problem of roller bar marks is more obvious, because it is necessary to consider both the water absorption of the product in an extremely low range and the relatively high production efficiency (i.e., a relatively short firing period), at this time, the sintering degree of the body inside is prone to be too high, and the surface layer of the body is prone to form softened roller marks due to overfiring. In view of the above situation, the common solution in the industry is to reduce the firing speed of the product (i.e., adjust the kiln) so that the temperature of the surface layer of the body and the inside of the body does not differ greatly, thereby achieving low water absorption while preventing the surface layer of the body from being excessively softened.

[0067] In one preferred embodiment of the present solution, in order to meet the market demand for high-value and high-performance ceramic products (the present solution refers specifically to a body with a water absorption of ≤0.5% and made of wet-process powder), adapt to the firing curve of the large-capacity kiln in the present solution, and have good adaptability to full-polished glaze, while improving the roller bar marks caused by excessive softening during high-temperature firing, the chemical composition of the body layer is optimized in the present solution.

[0068] Specifically, the content of Al2O3 in the low-hygroscopic powder is controlled to be 17.2-18.2% in the present solution, so as to avoid defects such as body softening, roller bar marks and even deformation of the body due to excessively low content, and also to prevent the body formula from requiring a high firing temperature due to excessively high content, thereby failing to achieve the low-temperature and fast-firing mechanism required by the present solution.

[0069] Further, in order to adapt to the Al2O3 content in the formula, the flux system of the body formula is designed as a CaO-MgO-K2O-Na2O quaternary system. In addition to controlling the total content of the fluxing components, the content of each fluxing component is also controlled. The gradient fluxing effect brought by the quaternary fluxing system makes the product not prone to excessive softening of the body due to the sharp softening of the liquid phase caused by a single fluxing during high-temperature firing.

[0070] It should be noted that the water absorption of the body mainly reflects the strength of the ceramic product, and the strength of the ceramic product also determines its market positioning. Generally speaking, the lower the water absorption, the higher the strength of the ceramic product, which is suitable for the mid-to-high-end market. In addition, in the preparation process of the ceramic green body, the powdering process of the body powder mainly includes wet powdering and dry powdering process. The process flow of wet powdering is mainly to first wet ball mill the prepared body raw materials with water to form a slurry, and then spray granulation through a spray tower to obtain a powder. The prepared powder particles have the characteristics of low hardness, large particle size and low fine powder content. The process flow of dry powdering is mainly to first de-iron and crush the prepared body raw materials, and then powdering through a vertical dry mill to obtain fine powder with the required moisture content. After de-ironing and deslagging, the fine powder is humidified and granulated to obtain powder with a particle size that meets the production requirements. The prepared powder particles have the characteristics of high hardness, small particle size and high fine powder content. Compared with wet powdering, although dry powdering has the disadvantages of easy appearance of small pits on the surface of the body, poor flatness, obvious orange peel effect, and possible black heart and black spot on the body after firing, it has obvious advantages of energy saving and low cost, and is mainly suitable for volume market and engineering order products. Wet powdering process has higher energy consumption, but the quality of the body is higher, so it is mainly suitable for the mid-to-high-end market.

[0071] Further, according to the mass percentage, the chemical composition of the low-hygroscopic dry powder includes SiO2 66.4-67.5%, Al2O3 17.2-18.2%, Fe2O3 1.6-2.7%, TiO2 0.3-0.5%, CaO 0.8-1.2%, MgO 1.8-2.3%, K2O 1.5-1.6%, Na2O 1.5-1.8%, and ignition loss 4.8-5.5%.

[0072] Further, in order to ensure the stability of the performance of the body in the whole process of forming, drying and firing, and at the same time meet the performance requirements of the present case, the present case proposes an embodiment of the chemical composition of the low-hygroscopic dry powder. In one specific embodiment, the present case also controls the ignition loss (I.L) of the low-hygroscopic dry powder to be less than 5.5%, in order to reduce the gaseous products of the body, further ensure the quality of the body, and meet the market demand for high-value high-performance ceramic products.

[0073] It should be noted that the skilled in the art can configure the chemical composition of the low-hygroscopic powder in the present scheme according to the local raw material resources, and the present scheme does not limit the composition and ratio of the raw material scheme.

[0074] Preferably, according to the mass percentage, the raw materials of the low-hygroscopic powder consist of 3% bentonite, 12% bauxite, 32% green sand, 2.5% magnesia soil, 5% broken brick powder, 8% mixed mud, 4% washed mud, 7% edge polishing mud, 1.5% talc and 25% yellow sand.

[0075] In a preferred embodiment of the present technical scheme, a specific raw material ratio scheme of the low-hygroscopic powder is also proposed.

[0076] In the raw material formula, the main role of bentonite is to improve the plasticity and strength of the body during shaping and transportation, and to reduce the occurrence of broken brick.

[0077] The addition amount of bauxite in the raw material formula is controlled at 12%, and mixed mud and washed mud are introduced in the raw material formula as a supplement of Al2O3 in the chemical composition. Since the main mineral of mixed mud and washed mud is kaolinite, compared with the multi-water hard / soft diaspore, kaolinite is easier to sinter, so it can better match the low-temperature fast firing mechanism of the present scheme.

[0078] Green sand is a kind of sand material, mainly produced in Rongchang and Yongchuan districts of Chongqing, and is a special ceramic raw material in the local area. This kind of raw material has good sintering plasticity and large reserves, and is easy to obtain. If it is added in large quantities in the body formula, the raw material cost can be greatly reduced. At the same time, due to the chemical composition of green sand also containing a certain amount of MgO, K2O and Na2O, green sand has good fluxing effect.

[0079] Magnesia soil is the main source of MgO in the chemical composition, which has the effects of fluxing and whitening to some extent. In addition, talc is a supplementary source of MgO in the chemical composition, and the combination of the two can increase the stability of the formula.

[0080] Yellow sand is also a cheap and white local raw material in Chongqing, which has good economic benefits. However, due to the extremely low Al2O3 content in the raw material, excessive use will lead to a decrease in the overall Al2O3 content of the formula, causing the softening of the body.

[0081] Broken brick powder is a clinker formed by crushing the secondary waste product after firing. When the clinker is added to the raw material composed of other raw materials, it can promote the fast firing of the body layer and further reduce the production energy consumption of the body, thereby effectively promoting the rapid firing of the body and shortening the firing period. At the same time, it can replace the traditional feldspar material as a fluxing component in the formula, which has obvious fluxing effect and can effectively reduce the raw material cost.

[0082] Edge polishing mud is a common waste in the field of building ceramics, which is mainly produced in the process of grinding and polishing of ceramic tiles. Its main minerals are glass phase, quartz and mullite, and it also contains a small amount of silicon carbide and grinding block resin, which is easy to foam. As a solid waste material, the cost of outsourcing treatment is relatively high, and it is usually used in body formula to reduce the cost of formula. However, in the process of use, it is necessary to strictly control its use in low water absorption body (water absorption ≤0.5%), because the low water absorption body produces more liquid phase in the high temperature firing process (used to support the density of the body), which will affect the exhaust of the easy foaming materials such as silicon carbide and resin in the edge polishing mud, thereby affecting the glaze quality of the ceramic tile products using the above body.

[0083] Further, the specifications of the small thickness body layer, the medium thickness body layer and the large thickness body layer are all 800mm×800mm, and in the large capacity kiln, the front side edges of the small thickness body layer, the medium thickness body layer and the large thickness body layer along the conveying direction all form an included angle one with the width direction of the large capacity kiln, and the angle of the included angle one is 5-11°.

[0084] Further, the specifications of the small thickness body layer, the medium thickness body layer and the large thickness body layer are all 800mm×800mm, and in the large capacity kiln, the front side edges of the small thickness body layer, the medium thickness body layer and the large thickness body layer along the conveying direction all form an included angle one with the width direction of the large capacity kiln, and the angle of the included angle one is 5-11°.

[0085] As shown in Figure 1 ∠A, which is an included angle one diagram formed by the 800 specification (i.e. 800mm×800mm) ceramic tile product and the width direction of the large capacity kiln in the present scheme. As shown in Figure 2 ∠B, which is an included angle two diagram formed by the 715 specification (i.e. 750mm×1500mm) ceramic tile product and the width direction of the large capacity kiln in the present scheme, i.e. the included angle formed by the short side (750mm edge) of the body layer and the width direction of the large capacity kiln.

[0086] In the mixed firing process of the present scheme, the body layer is placed on the roller at a certain small angle before entering the kiln, which can significantly improve the roller mark defects after firing. The core principle lies in changing the contact state and stress mode of the body layer and the roller, thereby reducing the local deformation and stress concentration of the brick body in the high temperature plastic stage. The specific reasons are as follows:

[0087] Firstly, when the body layer is placed horizontally, the roller exerts force on the edge of the body layer, which is equivalent to a fulcrum at the center of the body layer, and the edge is easy to bend and deform. When the body layer is placed obliquely, the edge of the body layer is close to the support point of the roller, the force arm is shortened, and the deformation is naturally reduced.

[0088] Second, when the green body layer is placed horizontally, only two narrow edges contact the roller, and the pressure is easy to concentrate; when placed obliquely, the contact line is long, and the unit area pressure is dispersed.

[0089] Second, when the green body layer is placed horizontally, the shrinkage of the green body layer is resisted by the frictional resistance of the roller, and the two sides form inward pulling stress, which is easy to form marks at the edges. When placed obliquely, the direction of the frictional force changes, and is decomposed into axial and transverse components, the transverse component is reduced, and the longitudinal shrinkage is more free.

[0090] Further, the expansion coefficient of the low-expansion glaze is (6.6-6.8) x 10 -6 / ℃; according to mass fraction, the raw materials of the low-expansion glaze include 36-40 parts of sodium feldspar, 9-11 parts of kaolin, 2-4 parts of quartz, 7-9 parts of nepheline, 10-14 parts of alumina, 10-14 parts of potassium feldspar, 14-16 parts of burned soil, 1-3 parts of burned talc, and 10-14 parts of zirconium silicate;

[0091] The expansion coefficient of the medium-expansion glaze is (7.3-7.5) x 10 -6 / ℃; according to mass fraction, the raw materials of the medium-expansion glaze include 38-42 parts of sodium feldspar, 9-11 parts of kaolin, 4-6 parts of quartz, 9-11 parts of nepheline, 12-16 parts of alumina, 10-14 parts of potassium feldspar, 5-7 parts of burned soil, 2-4 parts of burned talc, and 10-14 parts of zirconium silicate.

[0092] In order to simplify the preparation process of glazes with different expansion coefficients, the raw material ratio of the glaze is also optimized in the scheme. On the basis of small changes in the types of raw materials, only the ratio of the raw materials needs to be simply adjusted to obtain the glazes with different expansion coefficients required for production, thereby improving the production efficiency of ceramic tile products.

[0093] Preferably, according to mass fraction, the raw materials of the low-expansion glaze include 38 parts of sodium feldspar, 10 parts of kaolin, 3 parts of quartz, 8 parts of nepheline, 12 parts of alumina, 12 parts of potassium feldspar, 15 parts of burned soil, 2 parts of burned talc, and 12 parts of zirconium silicate;

[0094] According to mass fraction, the raw materials of the medium-expansion glaze include 40 parts of sodium feldspar, 10 parts of kaolin, 5 parts of quartz, 10 parts of nepheline, 14 parts of alumina, 12 parts of potassium feldspar, 6 parts of burned soil, 3 parts of burned talc, and 12 parts of zirconium silicate.

[0095] Further, the full polishing glaze of the small-thickness glaze blank, the full polishing glaze of the medium-thickness glaze blank, and the full polishing glaze of the large-thickness glaze blank are the same; the raw materials of the full polishing glaze are composed of sodium feldspar, kaolin, burned soil, dolomite, quartz, calcite, alumina, zinc oxide, and strontium carbonate;

[0096] The full polishing enamel has a silicon aluminum ratio of 3.0-3.2, and the content of Na2O in the full polishing enamel is 4.2-5.2% and the content of SrO is 3.3-4.3% according to mass percentage.

[0097] The polishing enamel is a kind of almost molten glass structure, and the raw material scheme of the present scheme belongs to raw material transparent glaze, is basically not opaque, has high light transmittance, strong penetration, good color development, and has physical and chemical properties such as stain resistance, wear resistance, corrosion resistance, and the like, and has short firing time.

[0098] Compared with the traditional transparent full polishing enamel, the present scheme selects sodium feldspar in alkali metal as the main flux, and dolomite, strontium carbonate and zinc oxide in alkali earth metal. Dolomite is a very cheap calcium magnesium raw material in natural minerals; zinc oxide is helpful to excellent color development of the polishing enamel formula.

[0099] Strontium carbonate can replace CaO and ZnO in the formula by equal amount in the firing process, thereby further increasing the fluxing effect and increasing the fluidity. In addition, strontium carbonate can decompose into SrO (SrCO3→SrO+CO2↑) in the temperature range of 800-1000℃, and SrO can react with SiO2 to produce low-melting-point strontium silicate (SrSiO3), which can accelerate the formation of glaze layer glassification and meet the requirements of low-temperature fast firing. In addition, the raw material formula of the present scheme belongs to a low-viscosity formula (i.e. has a relatively low high-temperature viscosity), so that the micropores generated by the early decomposition of strontium silicate can also be quickly filled with low-viscosity melt and form a non-porous surface, achieving surface densification. At the same time, the low-viscosity formula can also cooperate with other layer structures of the ceramic tile product (such as the body layer) to quickly exhaust. It should be noted that since strontium silicate is completely decomposed before 1000℃, even under the low-temperature fast firing mechanism of the present scheme, pinholes on the glaze surface caused by residual CO2 can be prevented.

[0100] Further, the refractive index of SrO is 1.83, and the refractive index of strontium silicate formed in the vitrification reaction is 1.65. The introduction of strontium carbonate can also enhance the gloss of the glaze surface, reduce scattering, and form a mirror effect. Sr 2+ occupies the [SiO4] network gap, can hinder the nucleation and growth of silicate crystals (such as wollastonite and diopside), reduce the loss of transparency or crystalline spots of the glaze surface, and is very beneficial to maintaining the high transparency of the glaze layer.

[0101] Further, strontium carbonate is also a color development aid. SrO can replace part of CaO, reduce the oxidation tendency of Cr 3+ , and stabilize the pink color development. It is found in the test debugging process that the system is also very beneficial to the color development of red in cooperation with zinc oxide.

[0102] In the chemical composition of the full polishing glaze, the SiO2 / Al2O3 ratio in the chemical composition is also limited, and the contents of the fluxing components Na2O and SrO in the chemical composition are also optimized, so that the full polishing glaze forms a sodium-strontium system polishing glaze in the chemical composition. The traditional full polishing glaze is generally a potassium-barium system polishing glaze, which is sensitive to the content of silicon in the chemical composition. If the corrosion resistance of the glaze layer is improved by increasing the content of silicon, the number of pores on the glaze surface will increase, thereby reducing the stain resistance of the glaze layer. Compared with the traditional potassium-barium system polishing glaze, the sodium-strontium system polishing glaze can simultaneously increase the contents of aluminum and silicon in the polishing glaze, while taking into account the corrosion resistance and stain resistance of the glaze layer.

[0103] Further, the chemical composition of the full polishing glaze includes, in terms of mass percentage, SiO2 45.0-49.0%, Al2O3 14.7-15.6%, Fe2O3 0.1-0.2%, TiO2 0.05-0.1%, CaO 8.5-9.5%, MgO 2.5-3.5%, K2O 0.1-0.3%, Na2O 4.2-5.2%, ZnO 3.4-4.4%, SrO 3.3-4.3%, and loss on ignition 8.0-12.0%.

[0104] Further, in order to ensure the stable performance of the glaze layer during the firing process and meet the performance requirements of the present application, an embodiment of the chemical composition of the full polishing glaze is provided.

[0105] Preferably, the raw materials of the full polishing glaze consist of, in terms of mass percentage, sodium feldspar 52.5%, highland clay 6%, burned clay 6%, dolomite 15%, quartz 2%, calcite 7%, aluminum oxide 2%, zinc oxide 4%, and strontium carbonate 5.5%.

[0106] Further, an embodiment of the raw material ratio of the full polishing glaze is provided.

[0107] Further, the application amount of the full polishing glaze is 420-480 g / m 2 .

[0108] The inkjet amount of the color ink of the small-thickness glaze blank, the color ink of the medium-thickness glaze blank, and the color ink of the large-thickness glaze blank is 4.8-9.6 g / m 2 .

[0109] The application amount of the glaze and the inkjet amount of the color ink also affect the deformation degree of the fired ceramic tile product to some extent. Therefore, in order to take into account the production cost and production quality of the ceramic tile product, the application amount of the glaze and the inkjet amount are also optimized.

[0110] Embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0111] Example

[0112] A. Mix the raw materials of the low hygroscopic powder, add water and ball mill, and adjust the ball milling fineness to obtain small thickness slurry, medium thickness slurry and large thickness slurry respectively;

[0113] The low-hygroscopic powder, by mass percentage, is composed of bentonite 3%, bauxite 12%, green sand 32%, magnesia 2.5%, broken brick powder 5%, mixed mud 8%, washed mud 4%, edge grinding and polishing mud 7%, talc 1.5%, and yellow sand 25%. The chemical composition of the low-hygroscopic powder prepared from the above-mentioned raw materials, by mass percentage, includes SiO2 66.77%, Al2O3 17.71%, Fe2O3 1.85%, TiO2 0.35%, CaO 0.92%, MgO 2.16%, K2O 1.56%, Na2O 1.67%, and loss on ignition 4.98%, with the remainder being unavoidable impurities in the formulation system. Furthermore, when preparing a thin slurry, a body strengthening agent, by mass percentage, is added to the above raw materials at 0.1% of the dry material weight.

[0114] By mass percentage, the thin-thickness slurry, when passed through a 325-mesh sieve, has a residue of 2.9%; the medium-thickness slurry, when passed through a 325-mesh sieve, has a residue of 2.0%; and the thick-thickness slurry, when passed through a 325-mesh sieve, has a residue of 1.6%.

[0115] It should be noted that the chemical compositions of the raw materials for the above-mentioned low-hygroscopic powder are as follows:

[0116] The chemical composition of the bauxite, by mass percentage, includes 41.64% SiO2, 40.99% Al2O3, 1.59% Fe2O3, 1.08% TiO2, 0.29% CaO, 0.38% MgO, 0.65% K2O, 0.31% Na2O, and 12.89% loss on ignition.

[0117] The chemical composition of the bentonite, by mass percentage, includes 68.45% SiO2, 14.57% Al2O3, 0.81% Fe2O3, 0.11% TiO2, 1.48% CaO, 1.59% MgO, 2.91% K2O, 1.67% Na2O, and 7.02% loss on ignition.

[0118] The chemical composition of the green sand includes SiO2 69.51%, Al2O3 14.73%, Fe2O3 3.19%, TiO2 0.31%, CaO 1.41%, MgO 1.83%, K2O 1.74%, Na2O 3.87% and loss on ignition 2.59% by mass.

[0119] The chemical composition of the magnesite soil includes SiO2 62.59%, Al2O3 5.79%, Fe2O3 1.62%, TiO2 0.13%, CaO 0.79%, MgO 21.41%, K2O 0.25%, Na2O 0.25% and loss on ignition 6.04% by mass.

[0120] The chemical composition of the rotten brick powder includes SiO2 65.67%, Al2O3 18.0%, Fe2O3 1.75%, TiO2 0.5%, CaO 0.62%, MgO 1.77%, K2O 1.92% and Na2O 2.09% by mass.

[0121] The chemical composition of the mixed mud includes SiO2 69.35%, Al2O3 20.5%, Fe2O3 0.94%, TiO2 0.43%, CaO 0.98%, MgO 0.3%, K2O 1.06%, Na2O 0.17% and loss on ignition 7.21% by mass.

[0122] The chemical composition of the washed mud includes SiO2 49.1%, Al2O3 33.74%, Fe2O3 2.11%, TiO2 0.2%, CaO 0.23%, MgO 0.58%, K2O 2.56%, Na2O 0.31% and loss on ignition 11.09% by mass.

[0123] The chemical composition of the edge grinding and polishing mud includes SiO2 67.48%, Al2O3 18.0%, Fe2O3 1.6%, TiO2 0.38%, CaO 2.12%, MgO 2.46%, K2O 2.05%, Na2O 2.14% and loss on ignition 1.77% by mass.

[0124] The chemical composition of the talc includes SiO2 32.24%, Al2O3 0.69%, Fe2O3 0.22%, TiO2 0.03%, CaO 1.76%, MgO 37.57%, K2O 0.01%, Na2O 0.09% and loss on ignition 27.0% by mass.

[0125] The chemical composition of the yellow sand includes SiO2 79.63%, Al2O3 9.53%, Fe2O3 0.65%, TiO2 0.22%, CaO 0.24%, MgO 0.32%, K2O 1.63%, Na2O 0.22% and loss on ignition 2.8% in percentage of mass.

[0126] B, respectively, the small thickness slurry, medium thickness slurry and large thickness slurry is sprayed into the spray granulation tower, and small thickness powder, medium thickness powder and large thickness powder are obtained in turn by spray granulation;

[0127] C, respectively, the small thickness powder, medium thickness powder and large thickness powder are pressed to obtain small thickness green body layer, medium thickness green body layer and large thickness green body layer in turn;

[0128] Among them,

[0129] The pressure of the pressing is 40 MPa / m 2 ; the thickness of the small thickness green body layer is 7.4 mm, the thickness of the medium thickness green body layer is 9 mm, and the thickness of the large thickness green body layer is 10 mm; and the specifications of the small thickness green body layer, the medium thickness green body layer and the large thickness green body layer are all 800 mm×800 mm.

[0130] D, small thickness glaze blank, medium thickness glaze blank and large thickness glaze blank are prepared;

[0131] Among them, the small thickness glaze blank includes the small thickness green body layer, and the medium swelling surface glaze, color ink and full polishing glaze are applied on the top surface of the small thickness green body layer in turn from bottom to top;

[0132] The swelling coefficient of the medium swelling surface glaze in the small thickness glaze blank is 7.4×10 -6 / ℃, and the raw materials of the medium swelling surface glaze include sodium feldspar 40 parts, kaolin 10 parts, quartz 5 parts, nepheline 10 parts, aluminum oxide 14 parts, potassium feldspar 12 parts, burned soil 6 parts, burned talc 3 parts and zirconium silicate 12 parts in mass fraction. 2 .

[0133] The inkjet amount of the color ink in the small thickness glaze blank is 5.0 g / m 2 .

[0134] The medium thickness glaze blank includes the medium thickness green body layer, and the medium swelling surface glaze, color ink and full polishing glaze are applied on the top surface of the medium thickness green body layer in turn from bottom to top;

[0135] The swelling coefficient of the medium swelling surface glaze in the medium thickness glaze blank is 7.4×10 -6The raw materials of the medium swelling face glaze include 40 parts of sodium feldspar, 10 parts of kaolin, 5 parts of quartz, 10 parts of nepheline, 14 parts of alumina, 12 parts of potassium feldspar, 6 parts of burned soil, 3 parts of burned talc and 12 parts of zirconium silicate, by mass fraction. The application amount of the medium swelling face glaze is 460 g / m 2 .

[0136] The inkjet amount of the color ink in the medium-thickness glaze blank is 5.0 g / m 2 .

[0137] The large-thickness glaze blank includes the large-thickness body layer, and a balance face glaze, a color ink and a full-polish glaze which are sequentially applied from bottom to top on the top surface of the large-thickness body layer;

[0138] The balance face glaze in the large-thickness glaze blank is mixed by the medium swelling face glaze and the low swelling face glaze in a mass ratio of 1:1, wherein the expansion coefficient of the medium swelling face glaze is 7.4×10 -6 / ℃, and the raw materials of the medium swelling face glaze include 40 parts of sodium feldspar, 10 parts of kaolin, 5 parts of quartz, 10 parts of nepheline, 14 parts of alumina, 12 parts of potassium feldspar, 6 parts of burned soil, 3 parts of burned talc and 12 parts of zirconium silicate, by mass fraction; the expansion coefficient of the low swelling face glaze is 6.7×10 -6 / ℃, and the raw materials of the low swelling face glaze include 38 parts of sodium feldspar, 10 parts of kaolin, 3 parts of quartz, 8 parts of nepheline, 12 parts of alumina, 12 parts of potassium feldspar, 15 parts of burned soil, 2 parts of burned talc and 12 parts of zirconium silicate, by mass fraction. The application amount of the balance face glaze is 460 g / m 2 .

[0139] The inkjet amount of the color ink in the large-thickness glaze blank is 5.0 g / m 2 .

[0140] The full-polish glaze of the small-thickness glaze blank, the full-polish glaze of the medium-thickness glaze blank and the full-polish glaze of the large-thickness glaze blank are the same, and the raw materials of the full-polish glaze include sodium feldspar, kaolin, burned soil, dolomite, quartz, calcite, alumina, zinc oxide and strontium carbonate, and the full-polish glaze is obtained by reasonably configuring the above raw materials. According to the mass percentage, the chemical composition of the full-polish glaze includes SiO247.05%, Al2O315.14%, Fe2O30.17%, TiO20.08%, CaO 8.76%, MgO 3.08%, K2O 0.17%, Na2O 4.7%, ZnO 3.96%, SrO 3.86% and loss on ignition 10.67%, and the remaining content is the inevitable impurities in the formula system. The application amount of the full-polish glaze is 460 g / m 2 .

[0141] E. Place the thin-thickness glazed blank, the medium-thickness glazed blank, and the thick-thickness glazed blank in three brick feeding positions in the same width direction in the high-capacity kiln in sequence. A thin-thickness glazed blank, a medium-thickness glazed blank, and a thick-thickness glazed blank in the same width direction constitute a firing unit. There are a total of 100 firing units. The angle formed between the front edge of all glazed blanks along the conveying direction and the width direction of the high-capacity kiln is 10°.

[0142] Firing is carried out at a firing temperature of ≤1100℃ and a firing cycle of ≤30min.

[0143] The firing curve of the high-capacity kiln includes a preheating section, a preheating section, a medium-temperature section, a high-temperature section, a rapid cooling section, and a slow cooling section. In the preheating section, the surface temperature rises from room temperature to 950°C, and the bottom temperature rises from room temperature to 1100°C, taking 3.61 minutes. In the preheating section, the surface temperature rises from 950°C to 1110°C, and the bottom temperature drops from 1100°C to 1060°C, taking 2.13 minutes. In the medium-temperature section, the surface temperature rises from 1110°C to 1203°C. The bottom temperature rises from 1060℃ to 1226℃ in 7.85 minutes; the surface temperature of the high-temperature section is maintained at 1203℃ and the bottom temperature at 1226℃ in 4.4 minutes; the surface temperature of the rapid cooling section drops from 1203℃ to 570℃ and the bottom temperature drops from 1226℃ to 300℃ in 4.84 minutes; the surface temperature of the slow cooling section drops from 570℃ to room temperature and the bottom temperature drops from 300℃ to room temperature in 6.52 minutes.

[0144] After firing in step E, 10 firing units were randomly selected from 100 firing units. The fired products from these 10 units were then subjected to performance tests according to the test methods of the People's Republic of China National Standards GB / T 4100-2015 and GB / T 45817-2025. The results are shown in Table 1 below.

[0145] Table 1 Performance test results of each fired product in the examples

[0146]

[0147] As shown in Table 1, the performance test results indicate that this solution can achieve low-temperature rapid firing of fully polished glazed ceramic tiles of different thicknesses in the same kiln. The fired ceramic tile products not only meet the physical and chemical properties of fully polished glaze, but also balance the tile shape and body quality of fully polished glazed ceramic tile products of different thicknesses. The performance test results of roller printing meet the standard of GB / T 45817—2025, and the other performance test results meet the standard of GB / T 4100-2015.

[0148] The technical principles of the present application are described above in combination with specific embodiments. These descriptions are only for explaining the principles of the present application, and cannot be interpreted as limiting the protection scope of the present application in any way. Based on the explanations herein, other specific embodiments of the present application can be conceived by those skilled in the art without any creative effort, and these embodiments will all fall within the protection scope of the present application.

Claims

1. A multi-thickness glazed tile co-firing process, characterized in that: This method is applicable to high-capacity kilns, wherein the high-capacity kiln has three brick-feeding positions in the width direction, and the co-firing process includes the following steps: A. Mix the raw materials of the low hygroscopic powder, add water and ball mill, and adjust the ball milling fineness to obtain small thickness slurry, medium thickness slurry and large thickness slurry respectively; B. The thin-thickness slurry, medium-thickness slurry and thick-thickness slurry are sprayed into the spray granulation tower respectively, and the thin-thickness powder, medium-thickness powder and thick-thickness powder are obtained by spray granulation in sequence. C. After pressing the small-thickness powder, medium-thickness powder and large-thickness powder respectively, small-thickness green body layer, medium-thickness green body layer and large-thickness green body layer are obtained in sequence. D. Prepare multiple glaze blanks, wherein the glaze blanks are thin-thickness glaze blanks, medium-thickness glaze blanks and thick-thickness glaze blanks; E. Multiple glazed blanks are sequentially conveyed to the brick feeding position of the high-capacity kiln and fired in an environment with a firing temperature ≤1100℃ and a firing cycle ≤30min. In step A, by mass percentage, the thin-thickness slurry passes through a 325-mesh sieve with a residue of 2.7-3.2%; the medium-thickness slurry passes through a 325-mesh sieve with a residue of 1.8-2.3%; and the thick-thickness slurry passes through a 325-mesh sieve with a residue of 1.4-1.9%. The chemical composition of the low-hygroscopic powder includes Al2O3, CaO, MgO, K2O, and Na2O. By mass percentage, the Al2O3 content in the low-hygroscopic powder is 17.2-18.2%, the total content of CaO, MgO, K2O, and Na2O is 5.6-6.6%, the CaO content is ≥0.8%, the MgO content is ≥1.8%, the K2O content is ≥1.5%, and the Na2O content is ≥1.5%. In step C, the thickness of the short-thickness blank layer is 6.8–8.6 mm, the thickness of the medium-thickness blank layer is >8.6 mm and ≤9.4 mm, and the thickness of the long-thickness blank layer is >9.4 mm and ≤12 mm. In step D, the thin-thickness glazed blank includes the thin-thickness blank layer, and a medium-expansion glaze, colored ink, and a fully polished glaze applied sequentially from bottom to top on the top surface of the thin-thickness blank layer; wherein, the application amount of the medium-expansion glaze is 500-560 g / m². 2 The medium-thickness glazed blank includes the medium-thickness blank layer, and a medium-expansion surface glaze, colored ink, and fully polished glaze applied sequentially from bottom to top on the top surface of the medium-thickness blank layer; wherein, the application amount of the medium-expansion surface glaze is 420-480 g / m². 2 The thick glazed blank includes the thick blank body layer, and a balanced surface glaze, colored ink, and fully polished glaze applied sequentially from bottom to top on the top surface of the thick blank body layer; wherein, the balanced surface glaze is composed of a medium-expansion surface glaze and a low-expansion surface glaze mixed in a mass ratio of 1:1, and the application amount of the balanced surface glaze is 420-480 g / m³. 2 ; The coefficient of thermal expansion of the low-expansion glaze is (6.6~6.8)×10. -6 / ℃, the coefficient of thermal expansion of the medium-expansion glaze is (7.3~7.5)×10 -6 / ℃; In step E, the firing curve of the high-capacity kiln includes a preheating section, a preheating section, a medium-temperature section, a high-temperature section, a rapid cooling section, and a slow cooling section: In the preheating section, the surface temperature rises from room temperature to 950°C, and the bottom temperature rises from room temperature to 1100°C, taking 3.5–3.7 minutes; in the preheating section, the surface temperature rises from 950°C to 1110°C, and the bottom temperature drops from 1100°C to 1060°C, taking 2–2.2 minutes; in the medium-temperature section, the surface temperature rises from 1110°C to 1203°C, and the bottom temperature… The temperature rises from 1060℃ to 1226℃ in 7.7–7.9 minutes; the surface temperature of the high-temperature section is maintained at 1203℃ and the bottom temperature at 1226℃ in 4.3–4.5 minutes; the surface temperature of the rapid cooling section drops from 1203℃ to 570℃ and the bottom temperature drops from 1226℃ to 300℃ in 4.7–4.9 minutes; the surface temperature of the slow cooling section drops from 570℃ to room temperature and the bottom temperature drops from 300℃ to room temperature in 6.4–6.6 minutes. The firing temperature is determined by the British POLORS temperature measuring ring and reflects the equivalent temperature corresponding to the comprehensive thermal effect experienced at the location where the temperature measuring ring is placed during the entire actual firing process.

2. The multi-thickness glazed tile co-firing process according to claim 1, characterized in that: Step A further includes adding a preform strengthening agent, accounting for 0.1 to 0.2% of the dry raw material, to the thin-thickness slurry according to a mass ratio; In step C, the pressing pressure is 38–42 MPa / m. 2 .

3. The multi-thickness glazed tile co-firing process according to claim 1, characterized in that: According to the mass percentage, after firing in step E, the water absorption rate of the thin-thickness green body layer, the medium-thickness green body layer and the thick-thickness green body layer is ≤0.5%.

4. The multi-thickness glazed tile co-firing process according to claim 3, characterized in that: The chemical composition of the low-hygroscopic powder, by mass percentage, includes SiO2 66.4–67.5%, Al2O3 17.2–18.2%, Fe2O3 1.6–2.7%, TiO2 0.3–0.5%, CaO 0.8–1.2%, MgO 1.8–2.3%, K2O 1.5–1.6%, Na2O 1.5–1.8%, and loss on ignition 4.8–5.5%.

5. The multi-thickness glazed tile co-firing process according to claim 2, characterized in that: The dimensions of the thin-thickness billet layer, the medium-thickness billet layer, and the thick-thickness billet layer are all 800mm×800mm. In the high-capacity kiln, the front edge of the thin-thickness billet layer, the medium-thickness billet layer, and the thick-thickness billet layer along the conveying direction forms an angle 1 with the width direction of the high-capacity kiln. The angle 1 is 5 to 11°.

6. The multi-thickness glazed tile co-firing process according to claim 2, characterized in that: The dimensions of the thin-thickness blank layer, the medium-thickness blank layer, and the thick-thickness blank layer are all 750mm×1500mm. In the high-capacity kiln, the short edges of the thin-thickness blank layer, the medium-thickness blank layer, and the thick-thickness blank layer all form an angle 2 with the width direction of the high-capacity kiln, and the angle of the angle 2 is 7 to 13°.

7. The multi-thickness glazed tile co-firing process according to claim 1, characterized in that: According to the mass fractions, the raw materials of the low-expansion glaze include 36-40 parts of sodium feldspar, 9-11 parts of kaolin, 2-4 parts of quartz, 7-9 parts of nepheline, 10-14 parts of alumina, 10-14 parts of potassium feldspar, 14-16 parts of calcined clay, 1-3 parts of calcined talc, and 10-14 parts of zirconium silicate. According to the mass fractions, the raw materials of the medium-expansion glaze include 38-42 parts of sodium feldspar, 9-11 parts of kaolin, 4-6 parts of quartz, 9-11 parts of nepheline, 12-16 parts of alumina, 10-14 parts of potassium feldspar, 5-7 parts of calcined clay, 2-4 parts of calcined talc, and 10-14 parts of zirconium silicate.

8. The multi-thickness glazed tile co-firing process according to claim 1, characterized in that: The fully polished glaze of the thin-thickness glaze blank, the fully polished glaze of the medium-thickness glaze blank, and the fully polished glaze of the thick-thickness glaze blank are the same. The raw materials for the fully polished glaze are composed of albite, kaolin, calcined clay, dolomite, quartz, calcite, alumina, zinc oxide and strontium carbonate; The silicon-to-aluminum ratio of the fully polished glaze is 3.0 to 3.2, and the Na2O content in the fully polished glaze is 4.2 to 5.2% and the SrO content is 3.3 to 4.3% by mass percentage.

9. The multi-thickness glazed tile co-firing process according to claim 8, characterized in that: According to mass percentage, the chemical composition of the fully polished glaze includes SiO2 45.0-49.0%, Al2O3 14.7-15.6%, Fe2O3 0.1-0.2%, TiO2 0.05-0.1%, CaO 8.5-9.5%, MgO 2.5-3.5%, K2O 0.1-0.3%, Na2O 4.2-5.2%, ZnO 3.4-4.4%, SrO 3.3-4.3%, and loss on ignition 8.0-12.0%.

10. The multi-thickness glazed tile co-firing process according to claim 1, characterized in that: The glazing application amount for the fully polished glaze of the thin-thickness glaze blank, the medium-thickness glaze blank, and the thick-thickness glaze blank is 420-480 g / m². 2 ; The inkjet volume for the color ink on the thin-thickness glaze blank, the medium-thickness glaze blank, and the thick-thickness glaze blank is 4.8–9.6 g / m³. 2 .

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