Process for preparing a demouldable ceramic jar

Abstract

The present application belongs to the field of pottery jar, aims at solving the problem of low production efficiency caused by the long time of wet embryo staying in the gypsum model during the preparation process of the existing pottery jar, and provides a pottery jar preparation process, which comprises the following steps: S100, preparing mud material by mixing main material and water, wherein the main material comprises raw material and clinker, and the clinker accounts for 6wt%-10wt% of the main material; S200, obtaining wet embryo by molding the mud material through the gypsum model; S300, obtaining the pre-product by demolding after drying the wet embryo through the first drying process; S400, obtaining the pottery jar by the pre-product through the second drying process and the sintering process. Through the improvement of mud material ratio, the addition of gypsum model drying, the improvement of gypsum model plaster water ratio, and the improvement of wet embryo structure and drying process, the present application realizes the substantial reduction of the wet embryo staying time in the gypsum model under the premise of ensuring the shape stability of the wet embryo when demolding, reduces the energy consumption, and improves the production capacity.

Description

Technical Field

[0001] This invention relates to the field of ceramic jars, and more specifically, to a process for preparing ceramic jars that are easy to demold. Background Technology

[0002] Earthenware jars are traditional containers, typically made of clay, and produced through processes such as shaping, drying, and firing. The preparation of earthenware jars usually involves selecting materials, shaping the clay, trimming and decorating, drying, and firing. The shaping process uses plaster molds to form the clay, but for the wet clay to be successfully demolded, its moisture content needs to be low. However, if the initial moisture content of the clay is too low, it is not conducive to rolling and shaping. Therefore, when the initial moisture content of the clay is high, the wet clay needs to remain in the plaster mold for a longer time, resulting in lower production efficiency. Summary of the Invention

[0003] The purpose of this invention is to provide an easy-to-demold ceramic jar preparation process, which solves the problem of low production efficiency caused by the need for wet blanks to remain in plaster molds for a long time in the existing ceramic jar preparation process.

[0004] The embodiments of the present invention are achieved through the following technical solutions:

[0005] A process for preparing easily demolded ceramic jars includes the following steps:

[0006] S100. Prepare mud by mixing the main material and water, wherein the main material includes raw material and cooked material, and the cooked material accounts for 6wt%-10wt% of the main material;

[0007] S200, the clay is molded into a wet blank through a plaster mold;

[0008] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain the pre-made product.

[0009] S400. The pre-made product is then subjected to a secondary drying process and a sintering process to obtain a ceramic jar.

[0010] In existing technologies, plaster molds are used to shape clay blanks. However, for successful demolding of wet blanks, the moisture content generally needs to be around 15%. If the initial moisture content of the clay is too low, it is not conducive to rolling and molding. Therefore, the initial moisture content of the clay is generally 20%-22%, and about 6% of the moisture needs to be lost. The wet blanks need to remain in the plaster molds for a relatively long time, resulting in low production efficiency. Typically, demolding from the plaster mold takes 2-3 days, and this time may be extended in winter when temperatures are low. The entire process is difficult to control accurately, resulting in low product quality consistency. Therefore, it is hoped that through technological improvements, the demolding time of wet blanks can be controlled within 24 hours, shortening the residence time of wet blanks in the plaster molds, reducing space occupation, increasing production capacity, and reducing energy consumption.

[0011] This invention ensures the permeability of the clay during firing while appropriately increasing the proportion of clinker. The clinker is preferably granular and free of powder, thus maintaining the plasticity of the clay. Furthermore, during roll forming, the plastic roller of the roll press can be replaced with a composite nylon roller. Because the hardness of composite nylon is significantly increased, its wear resistance is improved, extending the service life of the nylon roller by 2-3 times.

[0012] Preferably, step S300 includes: drying the plaster model again after demolding until the moisture content is 5wt%-8wt%.

[0013] Existing technology involves rolling the next batch of wet plaster molds directly after demolding. However, plaster molds have a certain water absorption capacity. During the molding and demolding process of the previous batch of wet molds, the plaster molds have already absorbed a certain amount of moisture, thus impairing their water absorption capacity. Consequently, if uniform process conditions are used during the molding and demolding process of the next batch of wet molds, the final product will exhibit performance differences, or even demolding failure. To meet demolding conditions, the retention time of the wet mold in the plaster mold will further increase. Therefore, this invention, in order to reduce the retention time of the wet mold in the plaster mold and improve process controllability, adds a drying process to the plaster mold. Experiments have shown that when the plaster mold is dried to a moisture content of no more than 8%, it can maintain good water absorption capacity without consuming excessive drying time. In addition, the bottom mold of the plaster mold can use a low-pressure rapid drainage process, using compressed air to drain water at any time, to avoid insufficient drying time for the bottom mold and failure to meet the moisture requirements.

[0014] Preferably, the drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold.

[0015] It facilitates the preheating of the kiln and can reduce energy consumption.

[0016] Preferably, the temperature of the waste heat from the kiln is 400℃-500℃, the temperature of the hot air generated by the hot air device is 100℃-150℃ higher than that of the waste heat from the kiln, and the drying time is 18h-22h.

[0017] While the waste heat from the kiln can be used directly to dry plaster models, the drying time is long, which contradicts the aforementioned goal of increasing production capacity. Therefore, this invention adds a hot air device inside the model, and the temperature of the hot air device is higher than that of the kiln. By controlling the temperature difference between the hot air and the waste heat from the kiln, the drying time of the plaster model can be minimized while ensuring the stability of its shape and structure.

[0018] Preferably, the plaster-to-water ratio of the plaster model is 100:(40-60).

[0019] The plaster model making process involves a chemical reaction between hemihydrate plaster and water. Adjusting the plaster-to-water ratio is crucial. High water content reduces the strength of the plaster model, while low water content results in insufficient porosity, affecting the model's capillary negative pressure water absorption function and preventing the wet blank from reaching the required moisture content quickly. Through numerous experiments, the plaster-to-water ratio was minimized while ensuring the plaster's porosity, strength, and drying stability. Because the plaster model undergoes repeated water absorption and drying processes under the preparation process of this invention, it experiences continuous linear shrinkage and slight expansion. Therefore, the structural stability and resilience of the plaster model under the preparation process of this invention must be ensured during the ratio adjustment process.

[0020] Preferably, the particle size of the main material is 48μm-58μm.

[0021] The main material can be ground using a ball mill. This invention increases the specific surface area of ​​the main material particles by reducing the particle size, thereby improving the plasticity of the clay and reducing the moisture content of the clay in the initial stage, thus further shortening the retention time of the wet blank in the plaster mold. Due to the increased hardness of the clay, the cast iron of the original roller shaft often breaks. Therefore, the material of the inner shaft of the plastic roller of the rolling mill can be improved to 40Cr special steel, which has high toughness and can ensure the service life of the equipment even with the increased hardness of the clay in this invention.

[0022] Preferably, the mass ratio of the main ingredient to water in S100 is 100:(15-18).

[0023] Because the particle size of the main ingredient is reduced, the ratio of the main ingredient to water can be adjusted to reduce the proportion of water.

[0024] Preferably, the height of the ceramic jar is greater than 2m, and the heat source for drying inside the embryo in the primary drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 40℃-50℃, the power of the electric heating device is 250w-300w, the distance between the electric heating device and the bottom wall of the wet embryo is 0.4m-0.6m, and the drying time is 16h-20h.

[0025] When the volume of the ceramic jar is large, especially its height, it is difficult to ensure that the hot air reaches the inner bottom wall of the wet blank using only a hot air device. Increasing the hot air speed may cause the wet blank to shrink and crack. For example, the upper part of the wet blank is closer to the hot air source, where the air velocity attenuation is lower. If the air velocity is increased, the body may crack under the influence of air pressure and / or accelerated shrinkage. Therefore, this invention adopts a combination of hot air and electric heating device. The electric heating device can be a heating lamp, which is set close to the bottom. Its heat is mainly used for drying the bottom and the side walls near the bottom. The hot air is mainly used for drying the upper part of the wet blank and the side walls near the upper part. After baking in this way for 17.5 hours, the thickest part of the bottom corner of the wet blank can be reached. The Shore hardness test shows a hardness of 80-90, which will not cause the blank to become too soft and crack after dehumidification.

[0026] In order to ensure uniform heat shrinkage in all parts of the wet embryo, the power of the electric heating device is regulated in this invention.

[0027] Preferably, the thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with the thickness at the edge of the bottom wall being 45mm-50mm and the thickness at the center of the bottom wall being 25mm-30mm.

[0028] Large ceramic jars may develop molding defects during demolding. Therefore, this invention ensures that the bottom and other parts have uniform hardness during the drying process, and further reduces the risk of bottom cracking by adjusting the bottom thickness. This reduces or avoids the use of scrap clay and eliminates the need to process scrap clay and return it to the raw material workshop.

[0029] Preferably, the sintering temperature is 1100℃-1200℃ and the sintering time is 50h-72h.

[0030] The present invention has at least the following beneficial effects:

[0031] This invention significantly reduces the retention time of wet blanks in plaster molds, reduces energy consumption, and increases production capacity by improving the clay material ratio, adding a drying process for plaster molds, improving the plaster-to-water ratio of plaster molds, and improving the structure and drying process of wet blanks, while ensuring the morphological stability of wet blanks when demolding. Detailed Implementation

[0032] To make the objectives, methods, and advantages of the embodiments of the present invention clearer, the methods in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0033] Example 1: A process for preparing an easy-to-demold ceramic jar, comprising the following steps:

[0034] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 6 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 48 μm. The mass ratio of the main material to water is 100:15.

[0035] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0036] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 5wt%.

[0037] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 400°C, and the temperature of the hot air generated by the hot air device is 100°C higher than that of the waste heat from the kiln; the drying time is 22 hours; and the plaster-to-water ratio of the plaster model is 100:40.

[0038] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 40℃ and the wind speed is 2.5m / s. The power of the electric heating device is 250w. The distance between the electric heating device and the bottom wall of the wet jar is 0.4m. The drying time is 16h.

[0039] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 45 mm at the edge and 25 mm at the center.

[0040] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0041] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0042] The sintering process is carried out at a temperature of 1100℃ for 72 hours.

[0043] Example 2: A process for preparing an easy-to-demold ceramic jar, comprising the following steps:

[0044] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 10 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 58 μm. The mass ratio of the main material to water is 100:18.

[0045] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0046] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 8 wt%.

[0047] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 500°C, and the temperature of the hot air generated by the hot air device is 150°C higher than that of the waste heat from the kiln; the drying time is 18 hours; and the plaster-to-water ratio of the plaster model is 100:60.

[0048] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the primary drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 50℃ and the wind speed is 4m / s. The power of the electric heating device is 300w. The distance between the electric heating device and the bottom wall of the wet jar is 0.6m. The drying time is 16h.

[0049] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 50 mm at the edge and 30 mm at the center.

[0050] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0051] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0052] The sintering process is carried out at a temperature of 1200℃ for 72 hours.

[0053] Example 3: A process for preparing an easy-to-demold ceramic jar, comprising the following steps:

[0054] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 50 μm. The mass ratio of the main material to water is 100:16.

[0055] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0056] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0057] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460°C, and the temperature of the hot air generated by the hot air device is 120°C higher than that of the waste heat from the kiln; the drying time is 20 hours; and the plaster-to-water ratio of the plaster model is 100:50.

[0058] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 45℃ and the wind speed is 3.5m / s. The power of the electric heating device is 270w. The distance between the electric heating device and the bottom wall of the wet jar is 0.5m. The drying time is 17.5h.

[0059] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 47 mm at the edge and 27 mm at the center.

[0060] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0061] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0062] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0063] Comparative Example 1: A process for preparing an easily demolded ceramic jar, comprising the following steps:

[0064] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 50 μm. The mass ratio of the main material to water is 100:16.

[0065] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0066] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0067] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460°C, and the temperature of the hot air generated by the hot air device is 120°C higher than that of the waste heat from the kiln; the drying time is 20 hours; and the plaster-to-water ratio of the plaster model is 100:50.

[0068] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 45℃ and the wind speed is 3.5m / s. The power of the electric heating device is 270w. The distance between the electric heating device and the bottom wall of the wet jar is 0.5m. The drying time is 17.5h.

[0069] The thickness of the bottom wall of the wet blank is 27 mm;

[0070] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0071] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0072] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0073] Comparative Example 2: A process for preparing an easy-to-demold ceramic jar, comprising the following steps:

[0074] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 50 μm. The mass ratio of the main material to water is 100:16.

[0075] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0076] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0077] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460℃, and the temperature of the hot air generated by the hot air device is the same as that of the waste heat from the kiln, and the drying time is 20 hours; the plaster-to-water ratio of the plaster model is 100:50.

[0078] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 45℃ and the wind speed is 3.5m / s. The power of the electric heating device is 270w. The distance between the electric heating device and the bottom wall of the wet jar is 0.5m. The drying time is 17.5h.

[0079] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 47 mm at the edge and 27 mm at the center.

[0080] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0081] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0082] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0083] Comparative Example 3: A process for preparing an easy-to-demold ceramic jar, comprising the following steps:

[0084] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 50 μm. The mass ratio of the main material to water is 100:22.

[0085] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0086] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0087] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460°C, and the temperature of the hot air generated by the hot air device is 120°C higher than that of the waste heat from the kiln; the drying time is 20 hours; and the plaster-to-water ratio of the plaster model is 100:50.

[0088] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 45℃ and the wind speed is 3.5m / s. The power of the electric heating device is 270w. The distance between the electric heating device and the bottom wall of the wet jar is 0.5m. The drying time is 17.5h.

[0089] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 47 mm at the edge and 27 mm at the center.

[0090] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0091] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0092] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0093] Comparative Example 4: A process for preparing an easy-to-demold ceramic jar, comprising the following steps:

[0094] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 50 μm. The mass ratio of the main material to water is 100:16.

[0095] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0096] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0097] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460°C, and the temperature of the hot air generated by the hot air device is 120°C higher than that of the waste heat from the kiln; the drying time is 20 hours; and the plaster-to-water ratio of the plaster model is 100:70.

[0098] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 45℃ and the wind speed is 3.5m / s. The power of the electric heating device is 270w. The distance between the electric heating device and the bottom wall of the wet jar is 0.5m. The drying time is 17.5h.

[0099] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 47 mm at the edge and 27 mm at the center.

[0100] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0101] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0102] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0103] Comparative Example 5: A process for preparing an easily demolded ceramic jar, comprising the following steps:

[0104] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 50 μm. The mass ratio of the main material to water is 100:16.

[0105] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0106] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0107] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460°C, and the temperature of the hot air generated by the hot air device is 120°C higher than that of the waste heat from the kiln; the drying time is 20 hours; and the plaster-to-water ratio of the plaster model is 100:50.

[0108] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the primary drying process includes: a hot air device with a hot air temperature of 45℃, a hot air velocity of 3.5m / s, and a drying time of 17.5h.

[0109] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 47 mm at the edge and 27 mm at the center.

[0110] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0111] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0112] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0113] Comparative Example 6: A process for preparing an easily demolded ceramic jar, comprising the following steps:

[0114] S100. Prepare mud by mixing the main material and water. The main material includes raw material and cooked material, with the cooked material accounting for 8 wt% of the main material. The mud is prepared using vacuum mud-making technology with a vacuum degree of 0.1 MPa, and then aged for three days. The particle size of the main material is 65 μm. The mass ratio of the main material to water is 100:16.

[0115] S200 clay is molded into a wet blank using a plaster mold; the molding method is roll forming.

[0116] S300. After the wet embryo is dried by a single drying process, it is demolded to obtain a pre-product. After demolding, the plaster model is dried again until the moisture content is 6wt%.

[0117] The drying heat source for the plaster model includes: waste heat from the kiln and a hot air device, wherein the hot air device is located inside the wet mold; the temperature of the waste heat from the kiln is 460°C, and the temperature of the hot air generated by the hot air device is 120°C higher than that of the waste heat from the kiln; the drying time is 20 hours; and the plaster-to-water ratio of the plaster model is 100:50.

[0118] The height of the ceramic jar is greater than 2m. The heat source for drying inside the jar in the one-time drying process includes: a hot air device and an electric heating device. The temperature of the hot air is 45℃ and the wind speed is 3.5m / s. The power of the electric heating device is 270w. The distance between the electric heating device and the bottom wall of the wet jar is 0.5m. The drying time is 17.5h.

[0119] The thickness of the bottom wall of the wet blank gradually decreases from the edge to the center, with a thickness of 47 mm at the edge and 27 mm at the center.

[0120] S400. After the pre-made product is trimmed and glazed, it is then dried and sintered to obtain a ceramic jar.

[0121] The secondary drying process includes: slow drying at room temperature for 10 days, drying at 45°C for 5 days, sintering when the moisture content of the bottom corner is less than 5%, drying at 800°C for 20 hours, and starting sintering when the moisture content is less than 1%.

[0122] The sintering process is carried out at a temperature of 1180℃ for 65 hours.

[0123] experiment:

[0124] raw material:

[0125] The raw material composition is 70% silicon dioxide, 22% aluminum oxide, 5.5% ferric oxide, with the balance being calcium, magnesium, potassium, and sodium. The calcium, magnesium, potassium, and sodium content refers to the total amount of compounds containing calcium, magnesium, potassium, and sodium ions.

[0126] The clinker composition is 45% mullite phase, 35% glass phase (monovalent potassium and sodium, divalent calcium and magnesium), 9% free quartz, 6% iron metal oxides, and 5% other impurities.

[0127] Experiment 1: Pottery jars with a height of 2.5m were prepared according to the pottery jar preparation processes provided in Examples 1-3 and Comparative Examples 1-6. The surface quality of the jars was then tested. The pottery jars prepared according to the processes provided in Examples 1-3 showed no cracks, no bubbles, and no deformation. Comparative Examples 1-6 all showed some bottom deformation, which is presumably related to insufficient drying before demolding. The yield rates are shown in Table 1.

[0128] Table 1

[0129] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Finished Product Rate 98.1％ 98.6％ 99.2％ 75.4％ 86.7％ Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Finished Product Rate 79.8％ 91.7％ 83.4％ 93.2％

[0130] As can be seen from the test results of Examples 1-3, the pottery jars prepared using the pottery jar preparation process provided in Examples 1-3 have a high yield.

[0131] As can be seen from the comparison between Comparative Examples 1-6 and Example 3, the structure of the wet mold bottom wall, the drying process of the plaster model, the ratio of main material to water, the paste-to-water ratio, the one-time drying process, and the particle size of the main material all affect the appearance quality of the product.

[0132] Experiment 2: Pottery jars were prepared according to the pottery jar preparation process provided in Examples 1-3 and Comparative Examples 1-6, and then the performance of the pottery jars was tested. The average value was taken after 5 tests for each group. The test results are shown in Table 2.

[0133] Table 2

[0134] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Flexural strength (MPa) 187.6 196.4 212.3 125.7 137.8 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Flexural strength (MPa) 128.8 164.2 153.5 169.1

[0135] As can be seen from the test results of Examples 1-3, the pottery jars made using the pottery jar preparation process provided in Examples 1-3 have good strength properties.

[0136] As can be seen from the comparison between Comparative Examples 1-6 and Example 3, the structure of the bottom wall of the wet clay body, the drying process of the plaster model, the ratio of main material to water, the paste-to-water ratio, the one-time drying process, and the particle size of the main material all affect the strength performance of the product. It is speculated that the reason is that the air bubbles and cracks that appear in the structure of the pottery jar affect the strength performance of the pottery jar.

[0137] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for the production of demouldable earthen jars, characterized in that, The method comprises the following steps: S100, preparing a mud material by mixing a main material and water, wherein the main material comprises raw material and clinker, and the clinker accounts for 6wt%-10wt% of the main material; S200, obtaining a wet embryo by molding the mud material through a gypsum model; S300, obtaining a preform by demolding after drying the wet embryo through a first drying process; S400, obtaining a pottery jar by performing a second drying process and a sintering process on the preform; The S300 comprises: drying the gypsum model again to a water content of 5wt%-8wt% after demolding; The heat energy source for drying the gypsum model comprises kiln waste heat and a hot air device, and the hot air device is arranged inside the wet embryo; The temperature of the kiln waste heat is 400℃-500℃, the temperature of the hot air generated by the hot air device is 100℃-150℃ higher than that of the kiln waste heat, and the drying time is 18h-22h; The plaster water ratio of the gypsum model is 100: (40-60); The height of the pottery jar is greater than 2m.

2. The process for the production of a demijohn according to claim 1, characterized in that, The particle size of the main material is 48μm-58μm.

3. A process for the production of a demijohn according to claim 2, characterized in that, The mass ratio of the main material to water in the S100 is 100: (15-18).

4. The drum manufacturing process according to claim 2, characterized in that, The height of the pottery jar is greater than 2m, the heat energy source for drying the embryo in the first drying process comprises a hot air device and an electric heating device, the temperature of the hot air is 40℃-50℃, and the wind speed of the hot air is 2.5m / s-4m / s; the power of the electric heating device is 250w-300w, the distance between the electric heating device and the bottom wall of the wet embryo is 0.4m-0.6m, and the drying time is 16h-20h.

5. The drum manufacturing process according to claim 2, characterized in that, The thickness of the bottom wall of the wet embryo gradually decreases from the edge to the center, the thickness of the edge of the bottom wall is 45mm-50mm, and the thickness of the center of the bottom wall is 25mm-30mm.

6. The drum manufacturing process according to claim 2, characterized in that, The temperature of the sintering process is 1100℃-1200℃, and the sintering time is 50h-72h.