Flat ceramic membrane and method for producing the same

Abstract

The application discloses a kind of flat ceramic membrane and its preparation method, it is related to ceramic filtration membrane technical field.The specific preparation method includes: (1) first powder is clothed, and bottom layer body is obtained;(2) the first powder in the bottom layer body pre-set region is removed, and a plurality of grooves are formed on the bottom layer body, the groove is along the first direction of the bottom layer body and penetrates the bottom layer body;(3) second powder is clothed into the groove, and intermediate body is obtained;(4) first powder is clothed on the intermediate body to form surface layer, and surface layer body is obtained;(5) the surface layer body is pressed, dried, and sintered, and flat ceramic membrane is obtained;Wherein, the second powder is burned in the sintering process and is burned out, and forms the hollow passage of flat ceramic membrane.The production efficiency of flat ceramic membrane can be effectively improved, and its cost is reduced by implementing the application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ceramic filtration membrane, in particular to a flat plate ceramic membrane and a preparation method thereof. BACKGROUND

[0002] The flat plate ceramic membrane is a new type of separation membrane material, which has excellent acid and alkali resistance, high temperature resistance, organic solvent resistance, mechanical properties and long service life, and has the advantages of easy cleaning and simple operation and maintenance in engineering use, so that the flat plate ceramic membrane has significant development potential in the fields of chemical industry, food, sewage treatment, biological medicine and seawater purification. Figure 1 Most of the flat plate ceramic membranes are rectangular, which comprises a plate body 1' and a hollow channel 2' arranged in the plate body 1'.

[0003] The existing preparation methods of ceramic flat plate membrane are generally divided into two categories: one is extrusion method, that is, the hollow ceramic flat plate membrane blank is integrally formed by high pressure extrusion, and then dried and fired. The extrusion method has the following defects: 1. The plasticity of the raw material is required to be high, the water content of the ceramic flat plate membrane blank is high, the drying energy consumption is large, and the deformation, crack and other defects are easy to occur. 2. The forming efficiency of the extrusion method is low, and the cost is high. Because of the slow forming, it is difficult to effectively match the drying and firing processes in the later stage, and it is difficult to realize continuous production. The second is dry pressing method, which basically comprises the following steps: a single piece of ceramic filtration membrane sheet is prepared by traditional dry pressing method, and then a flat plate ceramic membrane blank is formed by subsequent bonding process. The dry pressing method has the following disadvantages: 1. The production of single piece of ceramic filtration membrane sheet is difficult, specifically, the overall thickness of the flat plate ceramic membrane is about 5-10mm, and the thickness of the filtration membrane sheet is only 1-2mm, so it is difficult to ensure the uniformity and yield of the product by dry pressing. 2. The subsequent process is complicated, although the efficiency of pressing single piece of ceramic filtration membrane sheet is high, but a lot of time is needed for bonding and assembling of hollow structure in the later stage, and the yield of the subsequent process is difficult to guarantee.

[0004] In summary, the existing ceramic flat plate membrane has low production efficiency, which leads to high cost and limits its application. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a flat plate ceramic membrane and a preparation method thereof, which can greatly improve the production efficiency and reduce the preparation cost.

[0006] In order to solve the above technical problems, the present application provides a preparation method of flat plate ceramic membrane, which comprises:

[0007] (1) distributing the first powder to obtain a bottom layer blank;

[0008] (2) removing the first powder in the preset area of the bottom green body to form a plurality of grooves on the bottom green body, the grooves penetrating through the bottom green body along a first direction of the bottom green body;

[0009] (3) distributing the second powder into the grooves to obtain an intermediate green body;

[0010] (4) distributing the first powder on the intermediate green body to form a surface layer to obtain a surface layer green body;

[0011] (5) pressing, drying and firing the surface layer green body to obtain a flat ceramic membrane; wherein the second powder is burned out in the firing process to form a hollow channel of the flat ceramic membrane.

[0012] As an improvement of the above technical solution, the second powder comprises, by weight:

[0013] 100 parts of starch, 0.1-0.3 parts of suspending agent, and 0.05-0.1 parts of preservative;

[0014] The suspending agent is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol or hydroxyethyl cellulose.

[0015] The preservative is benzisothiazolinone or a benzisothiazolinone derivative.

[0016] As an improvement of the above technical solution, the first powder comprises, by weight:

[0017] 100 parts of raw material, 0.1-0.3 parts of suspending agent, and 0.1-0.2 parts of dispersing agent;

[0018] The raw material comprises one or more of alumina, clay, silicon carbide, silicon oxide, zirconium oxide, cordierite, perlite and diatomite.

[0019] The suspending agent is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol or hydroxyethyl cellulose, and the dispersing agent is selected from one or more of sodium tripolyphosphate, ammonium citrate or sodium silicate.

[0020] As an improvement of the above technical solution, the ratio of the width of the groove to the width of the hollow channel is (1-1.05):1.

[0021] The ratio of the depth of the groove to the depth of the hollow channel is (2-2.5):1.

[0022] The ratio of the spacing between adjacent grooves to the width of the groove is 1:(2-2.2).

[0023] As an improvement of the above technical solution, the first powder and the second powder are both prepared by ball milling, slurry, and spray drying process.

[0024] As the improvement of the above technical scheme, in step (2), the first powder in the preset area of the bottom body is sucked out through a plurality of suction pipes; wherein the vacuum degree of the suction pipe is 5-8kPa, and the ratio of the diameter of the suction pipe to the width of the groove is (0.9-1):1.

[0025] As the improvement of the above technical scheme, in step (3), the second powder is distributed into the groove through a plurality of print heads, wherein the moving speed of the print head is 80-100mm / s, and the outlet of the print head is vibrated by a vibrator when the second powder is printed, and the vibration frequency is 40-60Hz.

[0026] As the improvement of the above technical scheme, in step (5), the pressing pressure is 30-50MPa, the highest drying temperature is ≤200℃, and the drying time is 30-40min.

[0027] As the improvement of the above technical scheme, in step (5), the firing system is as follows:

[0028] from room temperature to 400℃, the heating rate is 20-40℃ / min;

[0029] from 400℃ to 600℃, the heating rate is 10-20℃ / min;

[0030] at 600℃, the holding time is 15-25min;

[0031] from 600℃ to the firing temperature, the heating rate is 20-30℃ / min;

[0032] at the firing temperature, the holding time is 5-20min;

[0033] wherein the firing temperature is 1000-1300℃.

[0034] Correspondingly, the application also discloses a flat plate ceramic membrane prepared by the preparation method of the flat plate ceramic membrane.

[0035] The application has the following beneficial effects:

[0036] The preparation method of the flat plate ceramic membrane removes part of the first powder on the bottom body formed by initial distribution, fills the burnable powder in the formed groove, then distributes and forms the surface layer, and finally performs pressing, drying and firing. Based on this preparation method, on the one hand, the pressing forming is adopted, which is more efficient than the extrusion forming; and the moisture of the powder required by the pressing forming is low, and the drying time is shorter than that of the extrusion method; compared with the extrusion method, the production efficiency is greatly improved. On the other hand, there is no need to perform subsequent complex assembly process like the traditional dry pressing method, so compared with the traditional dry pressing method, the production efficiency is also improved, the workpiece damage is reduced, and the yield is improved. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of a flat ceramic membrane in the prior art;

[0038] Figure 2 This is a flowchart of a method for preparing a flat ceramic membrane according to an embodiment of the present invention;

[0039] Figure 3 This is a schematic diagram illustrating the principle of step S3 of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0041] refer to Figure 2 This invention provides a method for preparing a flat ceramic membrane, specifically including the following steps:

[0042] S1: Apply the first powder material to obtain the bottom blank;

[0043] The first powder is a powder commonly used in various types of flat ceramic membranes in this field. Those skilled in the art can formulate specific formulas based on the composition system, molding requirements, and other process requirements of the flat ceramic membrane, and prepare the corresponding first powder. For example, for alumina-based flat ceramic membranes, the first powder is obtained by crushing and granulating alumina, sintering aids (such as cordierite and talc, but not limited to these), and clay (such as kaolin and bentonite, but not limited to these). Similarly, for silicon carbide-based flat ceramic membranes, the first powder is obtained by crushing and granulating silicon carbide, sintering aids (such as alumina, zinc oxide, and quartz, but not limited to these), and clay (such as kaolin and clay, but not limited to these), but is not limited to these.

[0044] The first powder can be prepared by a common ball milling-spray drying method, or by a dry powdering process (i.e., vertical milling-water granulation-fluidized shaping), or by a dry ball milling and water granulation process. Preferably, in one embodiment of the present invention, the first powder is prepared by a ball milling-spray drying process, which results in a first powder with high sphericity and good flowability.

[0045] Preferably, in one embodiment of the present invention, the first powder comprises, by weight:

[0046] 100 parts raw materials, 0.1-0.3 parts suspending agent, and 0.1-0.2 parts dispersant;

[0047] The raw materials are common raw materials for preparing various types of flat ceramic membranes in the art, such as alumina, clay, cordierite, silicon oxide and the like for preparing an alumina-based flat ceramic membrane; zirconia, clay, silicon oxide, perlite and the like for preparing a zirconia-based flat ceramic membrane; silicon carbide, clay, talc and the like for preparing a silicon carbide-based flat ceramic membrane, but are not limited thereto.

[0048] The suspending agent and the dispersing agent can improve the stability of the ball-milled slurry and the fluidity of the first powder. Specifically, the suspending agent can be one or more of sodium carboxymethyl cellulose, polyvinyl alcohol or hydroxyethyl cellulose, but is not limited thereto. The dispersing agent can be one or more of sodium tripolyphosphate, ammonium citrate or sodium silicate, but is not limited thereto.

[0049] The first powder can be distributed by a common distributor in the art, such as a wide-body one-time distribution equipment produced by Foshan Saipu Feite Machinery Co., Ltd., a belt-type distribution system, but is not limited thereto. Preferably, a through-body distributor in the ceramic tile field is used for distribution, such as a through-body digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. The through-body distributor is provided with multiple print heads to accurately print the powder to form a specific pattern. Based on the through-body distribution printer, a suction pipe can be additionally installed on one side of the print head of the through-body distributor to simply remove the second powder and further improve the production efficiency.

[0050] S2: removing the first powder in the preset area of the bottom body blank to form multiple grooves on the bottom body blank, the grooves penetrating through the bottom body blank along a first direction of the bottom body blank;

[0051] The first powder in the preset area can be dug out, sucked out or pushed out, but is not limited thereto. Preferably, in an embodiment of the present application, the first powder in the preset area of the bottom body blank is sucked out by multiple suction pipes. The vacuum degree of the suction pipe is 5-8 kPa. More preferably, referring to Figure 3 The multiple groups of suction pipes 3 are additionally installed on one side of the print head 4 of the through-body distributor.

[0052] Each suction pipe can form one groove after one suction, or form one groove after two or more suction. Preferably, referring to Figure 3 Each suction pipe 3 can form one groove 2 on the bottom body blank 1 after one suction of the first powder, and the ratio of the diameter of the suction pipe 3 to the width of the groove 2 is (0.9-1):1, so that the diameter of the suction pipe is slightly smaller than the width of the groove.

[0053] The bottom layer blank can be circular, rectangular, trapezoidal, but is not limited thereto. When it is circular, a plurality of grooves penetrate the bottom layer blank along a direction parallel to any diameter (not the thickness direction) to form hollow channels after subsequent sintering. When the bottom layer blank is rectangular, a plurality of grooves penetrate the bottom layer blank along the length direction of the bottom layer blank, but is not limited thereto.

[0054] The ratio of the width of the groove to the width of the hollow channel of the flat plate ceramic membrane product is (1-1.05):1, and the ratio of the depth of the groove to the depth of the hollow channel is (2-2.5):1. Based on this ratio, the strength and filtration flux of the flat plate ceramic membrane product can be effectively ensured. Further, the ratio of the spacing between adjacent grooves to the width of the groove is 1:(2-2.2). Based on this ratio, the flux of the flat plate ceramic membrane can be effectively improved.

[0055] S3: distributing the second powder into the grooves to obtain an intermediate blank;

[0056] The second powder is a powder that is sintered to form a hollow channel. Specifically, the sintering temperature (the temperature at which complete sintering occurs in an air atmosphere) of the second powder is 200-300°C lower than that of the first powder. Based on the above control, the second powder can be sintered sufficiently to form a hollow channel, and the second powder does not affect the sintering of the flat plate ceramic membrane, thereby avoiding defects such as cracking.

[0057] In order to form a hollow channel with good performance on the flat plate ceramic membrane, the flowability and compression performance of the second powder also need to be controlled. Specifically, the difference between the flowability f2 of the second powder and the flowability f1 of the first powder is |f2-f1|≤4mm. Based on this control, the difference in flowability between the two powders is small, which optimizes the distribution effect and the compression molding effect. Preferably, the difference between the flowability f2 of the second powder and the flowability f1 of the first powder is 1≤f2-f1≤4mm. The flowability of the second powder is controlled to be larger, which can better fill the grooves. The test method for flowability is as follows: a glass cylinder (or a smooth metal cylinder, a smooth ceramic cylinder, etc., but not limited thereto) with a diameter of 30mm and a height of 50mm is placed on a glass plate (or a smooth metal plate, a smooth ceramic plate, etc., but not limited thereto), the first powder / second powder is filled and leveled, then the glass cylinder is lifted, and the maximum height H of the material pile after the ceramic plate powder naturally flows away is recorded. s The flowability is calculated as follows:

[0058] f=50-H s

[0059] Wherein, f is the flowability of the ceramic powder, H s is the maximum height of the material pile formed during the flowability test.

[0060] Specifically, the relationship between the compression ratio ε2 of the second powder and the compression ratio ε1 of the first powder is: ε2 / ε2 = 1.05-1.3.

[0061] Preferably, in one embodiment of the present application, the second powder comprises, by weight:

[0062] 100 parts of starch, 0.1-0.3 parts of suspending agent, 0.05-0.1 parts of preservative;

[0063] Wherein, the suspending agent is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol or hydroxyethyl cellulose; the preservative is selected from benzisothiazolinone or benzisothiazolinone derivatives. The second powder of this formula can be well applied to alumina-based flat ceramic membranes.

[0064] Wherein, multiple print heads can be used to distribute the second powder into the grooves. More specifically, a full-body distributor in the field of ceramic tiles is used to distribute the second powder, such as the full-body digital distribution system produced by Guangdong Bohu Mechanical and Electrical Co., Ltd. During the distribution process, the moving speed of the print head is 80-100 mm / s, and a vibrator is used to vibrate the discharge port of the print head when printing the second powder, with a vibration frequency of 40-60 Hz. Through vibration, the outflow of the second powder can be accelerated, and the distribution efficiency can be improved.

[0065] S4: using the first powder to distribute on the intermediate body to form a surface layer, to obtain a surface layer body;

[0066] Wherein, the distribution of the first powder can be realized by a common distributor in the field, such as the wide-body one-time distribution equipment produced by Foshan Saipu Feite Machinery Co., Ltd., the belt-type distribution system, but not limited to. Preferably, a full-body distributor in the field of ceramic tiles is used for distribution, such as the full-body digital distribution system produced by Guangdong Bohu Mechanical and Electrical Co., Ltd.

[0067] S5: pressing, drying and firing the surface layer body to obtain a flat ceramic membrane;

[0068] Specifically, during the pressing process, the pressing pressure is 30-50 MPa, but not limited to. After the pressing is completed, the bending strength of the obtained body is 1-3 MPa.

[0069] Wherein, a roller kiln, an oven, etc. can be used for drying, but not limited to. Preferably, a roller kiln is used for drying, and the highest drying temperature is controlled to be ≤200°C during the drying process, and the drying time is 30-40 min.

[0070] Wherein, a roller kiln, a tunnel kiln, etc. can be used for firing, but not limited to. Preferably, a roller kiln is used for firing. The second powder is burned out during the firing process to form a hollow channel of the flat ceramic membrane.

[0071] Specifically, in one embodiment of the present application, the second powder mainly composed of starch is used, and the flat ceramic membrane is an alumina-based flat ceramic membrane, and the firing system is as follows: from room temperature to 400℃, the heating rate is 20-40℃ / min; from 400℃ to 600℃, the heating rate is 10-20℃ / min; at 600℃, the holding time is 15-25min; from 600℃ to the firing temperature, the heating rate is 20-30℃ / min; at the firing temperature, the holding time is 5-20min; wherein the firing temperature is 1000-1300℃. Based on the above firing system, the starch can be fully burned out (the carbonization temperature range is 400-600℃, and the oxidation temperature range is 600-1000℃), and the hollow channel is obtained. The oxidation of the starch can also be prevented from affecting the firing of the flat ceramic membrane.

[0072] Correspondingly, the present application also discloses a flat ceramic membrane prepared by the above preparation method.

[0073] The present application is further illustrated by specific examples as follows:

[0074] Example 1

[0075] The present embodiment provides a preparation method of a flat ceramic membrane, which comprises the following steps:

[0076] (1) preparing a first powder and a second powder;

[0077] The formula of the first powder is as follows: 90 parts of alumina, 2 parts of titanium oxide, 3 parts of silicon oxide, 5 parts of kaolin, 0.1 part of sodium carboxymethyl cellulose, and 0.3 part of ammonium citrate.

[0078] The preparation method of the first powder is as follows: the raw materials are mixed, and then loaded into a ball mill according to the ball-to-material ratio of 3:1:1, the ball milling speed is controlled to be 50rpm, the slurry is obtained after ball milling for 120min, and then the slurry is discharged and spray dried to obtain the first powder.

[0079] The test shows that the fluidity of the first powder is 37.5mm, and the compression ratio is 2.1.

[0080] The formula of the second powder is as follows:

[0081] 100 parts of starch, 0.2 part of polyvinyl alcohol, and 0.08 part of benzylpropylisothiazolinone.

[0082] The preparation method of the second powder is as follows: the raw materials are mixed, and then loaded into a ball mill according to the ball-to-material ratio of 2.5:1:1.2, the ball milling speed is controlled to be 50rpm, the slurry is obtained after ball milling for 50min, and then the slurry is discharged and spray dried to obtain the second powder.

[0083] The flowability of the second powder is 36 mm, and the compression ratio is 2.3.

[0084] (2) The first powder is distributed to obtain a bottom green body;

[0085] Specifically, the distribution thickness is 9 mm, the distribution width is 256 mm, and the distribution length is 615 mm, and a whole-body digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution.

[0086] (3) The first powder in the preset area of the bottom green body is removed to form a plurality of grooves on the bottom green body;

[0087] Among them, a plurality of suction pipes are used to suck out the first powder in the preset area of the bottom green body; the suction pipe is fixed in front of the print head of the whole-body digital distribution system, and the center lines of the two coincide. Specifically, the vacuum degree of the suction pipe is 6.5 kPa.

[0088] Among them, the width of the groove is 8.5 mm (the width of the hollow channel is 8 mm), the depth is 7.6 mm (the depth of the hollow channel is 4 mm), the spacing between adjacent grooves is 3.3 mm, and the diameter of the suction pipe is 7.6 mm.

[0089] (4) The second powder is distributed into the grooves to obtain an intermediate green body;

[0090] Specifically, the whole-body digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution. When distributing, the moving speed of the print head is 85 mm / s, and the vibrator vibration frequency is 55 Hz. The distributed second powder fills the grooves.

[0091] (5) The first powder is distributed on the intermediate green body to form a surface layer to obtain a surface layer green body;

[0092] Specifically, the distribution thickness is 4 mm, the distribution width is 256 mm, and the distribution length is 615 mm, and the whole-body digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution.

[0093] (6) The surface layer green body is pressed, dried, and fired to obtain a flat plate ceramic membrane;

[0094] Among them, the pressing pressure is 35 MPa, and the bending strength of the green body obtained by pressing is 2.2 MPa.

[0095] The pressed green body is dried in a roller kiln, the highest drying temperature is 200℃, and the drying time is 32 min.

[0096] The firing schedule during firing is:

[0097] From room temperature to 400℃, the heating rate is 35℃ / min;

[0098] from 400℃ to 600℃ at a heating rate of 18℃ / min;

[0099] holding at 600℃ for 20min;

[0100] from 600℃ to the sintering temperature at a heating rate of 22℃ / min;

[0101] holding at the sintering temperature for 12min;

[0102] wherein the sintering temperature is 1200℃.

[0103] Example 2

[0104] The embodiment provides a preparation method of a flat plate ceramic membrane, comprising the following steps:

[0105] (1) preparing a first powder and a second powder;

[0106] wherein the formula of the first powder is: 90 parts of alumina, 2 parts of titanium oxide, 3 parts of silicon oxide, 5 parts of kaolin, 0.1 part of sodium carboxymethyl cellulose, and 0.3 part of ammonium citrate;

[0107] The preparation method of the first powder is: mixing various raw materials, loading into a ball mill according to a ball-to-material ratio of 3:1:1, controlling the ball milling speed to be 50rpm, and obtaining slurry after ball milling for 120min, and then spray drying the slurry to obtain the first powder.

[0108] Test results show that the fluidity of the first powder is 37.5mm, and the compression ratio is 2.1.

[0109] wherein the formula of the second powder is:

[0110] 100 parts of starch, 0.2 part of polyvinyl alcohol, and 0.08 part of benzylpropylisothiazolinone;

[0111] The preparation method of the second powder is: mixing various raw materials, loading into a ball mill according to a ball-to-material ratio of 2.5:1:1.2, controlling the ball milling speed to be 50rpm, and obtaining slurry after ball milling for 50min, and then spray drying the slurry to obtain the second powder.

[0112] Test results show that the fluidity of the second powder is 36mm, and the compression ratio is 2.3.

[0113] (2) distributing the first powder to obtain a bottom green body;

[0114] Specifically, the distribution thickness is 9mm, the distribution width is 256mm, the distribution length is 615mm, and a digital distribution system produced by Guangdong Bohui Machinery and Electronics Co., Ltd. is used for distribution.

[0115] (3) removing the first powder in the preset region of the bottom green body to form a plurality of grooves on the bottom green body;

[0116] The first powder in the preset region of the bottom green body is sucked out by using a plurality of suction pipes. The suction pipes are fixed in front of the print head of the whole-body digital distribution system, and the center lines of the two coincide. Specifically, the vacuum degree of the suction pipe is 6.5 kPa.

[0117] The width of the groove is 8.2 mm (the width of the hollow channel is 8 mm), the depth is 8.2 mm (the depth of the hollow channel is 4 mm), the spacing between adjacent grooves is 4.1 mm, and the diameter of the suction pipe is 7.6 mm.

[0118] (4) distributing the second powder into the grooves to obtain an intermediate green body;

[0119] Specifically, the whole-body digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution. When distributing, the moving speed of the print head is 85 mm / s, and the vibration frequency of the vibrator is 55 Hz. The distributed second powder fills the grooves.

[0120] (5) distributing the first powder on the intermediate green body to form a surface layer to obtain a surface layer green body;

[0121] Specifically, the distribution thickness is 4 mm, the distribution width is 256 mm, and the distribution length is 615 mm. The whole-body digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution.

[0122] (6) pressing, drying and sintering the surface layer green body to obtain a flat plate ceramic membrane;

[0123] The pressing pressure is 35 MPa, and the bending strength of the green body obtained by pressing is 2.2 MPa.

[0124] The pressed green body is dried in a roller kiln, the highest drying temperature is 200℃, and the drying time is 32 min.

[0125] The sintering schedule during sintering is:

[0126] From room temperature to 400℃, the heating rate is 35℃ / min;

[0127] From 400℃ to 600℃, the heating rate is 18℃ / min;

[0128] At 600℃, keep for 20 min;

[0129] From 600℃ to the sintering temperature, the heating rate is 22℃ / min;

[0130] At the sintering temperature, keep for 12 min;

[0131] wherein the sintering temperature is 1200℃.

[0132] Embodiment 3

[0133] The embodiment provides a preparation method of a flat plate ceramic membrane, which comprises the following steps:

[0134] (1) preparing a first powder and a second powder;

[0135] wherein the formula of the first powder is: bauxite 85 parts, kaolin 5 parts, talc 5 parts, titanium oxide 2 parts, magnesium oxide 3 parts, hydroxyethyl cellulose 0.1 part, and sodium silicate 0.3 part;

[0136] The preparation method of the first powder is: mixing various raw materials, loading into a ball mill according to a ball-to-material ratio of 3:1:1, controlling the ball milling speed to be 55 rpm, and obtaining slurry after ball milling for 120 min, and then spray drying the slurry to obtain the first powder.

[0137] Test results show that the fluidity of the first powder is 37 mm, and the compression ratio is 2.2.

[0138] wherein the formula of the second powder is:

[0139] starch 100 parts, sodium carboxymethyl cellulose 0.2 part, and benzylidene isothiazolinone 0.08 part;

[0140] The preparation method of the second powder is: mixing various raw materials, loading into a ball mill according to a ball-to-material ratio of 2:1:1.2, controlling the ball milling speed to be 50 rpm, and obtaining slurry after ball milling for 30 min, and then spray drying the slurry to obtain the second powder.

[0141] Test results show that the fluidity of the second powder is 38 mm, and the compression ratio is 2.5.

[0142] (2) distributing the first powder to obtain a bottom green body;

[0143] Specifically, the distribution thickness is 9 mm, the distribution width is 256 mm, the distribution length is 615 mm, and a whole-body digital distribution system produced by Guangdong Bohui Machinery and Electronics Co., Ltd. is used for distribution.

[0144] (3) removing the first powder in a preset area of the bottom green body to form a plurality of grooves on the bottom green body;

[0145] wherein a plurality of suction pipes are used to suck out the first powder in the preset area of the bottom green body; the suction pipes are fixed in front of the print head of the whole-body digital distribution system, and the center lines of the suction pipes and the print head coincide. Specifically, the vacuum degree of the suction pipes is 6.5 kPa.

[0146] The width of the groove is 8.2 mm (the width of the hollow channel is 8 mm), the depth of the groove is 8.2 mm (the depth of the hollow channel is 4 mm), the distance between adjacent grooves is 4.1 mm, and the diameter of the suction pipe is 7.6 mm.

[0147] (4) distributing the second powder into the grooves to obtain an intermediate body;

[0148] Specifically, a digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution. When distributing, the moving speed of the print head is 85 mm / s, and the vibration frequency of the vibrator is 55 Hz. The distributed second powder fills the grooves.

[0149] (5) distributing the first powder on the intermediate body to form a surface layer to obtain a surface layer body;

[0150] Specifically, the distribution thickness is 4 mm, the distribution width is 256 mm, and the distribution length is 615 mm. A digital distribution system produced by Guangdong Bohu Machinery Co., Ltd. is used for distribution.

[0151] (6) pressing, drying, and firing the surface layer body to obtain a flat plate ceramic membrane;

[0152] The pressing pressure is 35 MPa, and the bending strength of the body obtained by pressing is 2.2 MPa.

[0153] The pressed body is dried in a roller kiln, the highest drying temperature is 200 ℃, and the drying time is 32 min.

[0154] The firing schedule during firing is as follows:

[0155] From room temperature to 400 ℃, the heating rate is 35 ℃ / min;

[0156] From 400 ℃ to 600 ℃, the heating rate is 18 ℃ / min;

[0157] At 600 ℃, the temperature is kept for 20 min;

[0158] From 600 ℃ to the firing temperature, the heating rate is 22 ℃ / min;

[0159] At the firing temperature, the temperature is kept for 12 min;

[0160] The firing temperature is 1200 ℃.

[0161] Comparative Example 1

[0162] The formula of the first powder in Example 1 is taken, and a flat plate ceramic membrane is prepared by the extrusion method commonly used in the art.

[0163] The flat plate ceramic membranes obtained from Examples 1-3 and Comparative Example 1 were tested according to the following methods:

[0164] (1) Bending strength: tested according to the method specified in GB / T 1965;

[0165] (2) Pure water flux: tested according to the method specified in GB / T 39717-2020.

[0166] The specific test results are as follows:

[0167] Flexural strength (MPa) Flux

L / (m 2 ·h·bar)

[0168] The above describes the preferred embodiments of the application. It should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements are also considered within the protection scope of the application.

[0169] The above describes the preferred embodiments of the application. It should be noted that for ordinary skilled persons in the art, several improvements and refinements can be made without departing from the principles of the application, and these improvements and refinements are also considered within the protection scope of the application.

Claims

1. A method for preparing a flat plate ceramic membrane, characterized by, The application relates to a preparation method of a flat ceramic membrane. The method comprises the following steps: (1) distributing a first powder to obtain a bottom body; the first powder is prepared by a ball milling slurry and a spray drying process; (2) removing the first powder in a preset area of the bottom body to form a plurality of grooves on the bottom body; the grooves penetrate through the bottom body along a first direction of the bottom body; (3) distributing a second powder into the grooves to obtain an intermediate body; the second powder is prepared by a ball milling slurry and a spray drying process; (4) distributing a first powder on the intermediate body to form a surface layer to obtain a surface layer body; (5) pressing, drying and sintering the surface layer body to obtain the flat ceramic membrane; wherein the second powder is sintered out during the sintering process to form a hollow channel of the flat ceramic membrane. The second powder comprises the following components in parts by weight: 100 parts of starch, 0.1-0.3 parts of a suspending agent and 0.05-0.1 parts of a preservative. The suspending agent is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol and hydroxyethyl cellulose. The preservative is selected from benzisothiazolinone or a benzisothiazolinone derivative. The first powder comprises the following components in parts by weight: 100 parts of raw materials, 0.1-0.3 parts of a suspending agent and 0.1-0.2 parts of a dispersing agent.

2. The method of claim 1, wherein the ceramic membrane is a flat sheet ceramic membrane. The raw materials include one or more of alumina, clay, silicon carbide, silicon oxide, zirconium oxide, cordierite, perlite and diatomite. The suspending agent is selected from one or more of sodium carboxymethyl cellulose, polyvinyl alcohol and hydroxyethyl cellulose. The dispersing agent is selected from one or more of sodium tripolyphosphate, ammonium citrate and sodium silicate. The ratio of the width of the groove to the width of the hollow channel is (1-1.05):

1.

3. The method of claim 1, wherein the ceramic membrane is a flat sheet ceramic membrane. The ratio of the depth of the groove to the depth of the hollow channel is (2-2.5):

1. The ratio of the spacing between adjacent grooves to the width of the groove is 1:(2-2.2). In step (2), the first powder in the preset area of the bottom body is sucked out through a plurality of suction pipes; the vacuum degree of the suction pipe is 5-8 kPa, and the ratio of the diameter of the suction pipe to the width of the groove is (0.9-1):

1. In step (3), the second powder is distributed into the grooves through a plurality of printing heads; the moving speed of the printing head is 80-100 mm / s, and the outlet of the printing head is vibrated by a vibrator when the second powder is printed; the vibration frequency is 40-60 Hz.

4. The method of claim 1, wherein the ceramic membrane is a flat sheet ceramic membrane. In step (5), the pressing pressure is 30-50 MPa, the highest drying temperature is less than or equal to 200 DEG C, and the drying time is 30-40 min. In step (5), the sintering system is as follows: from room temperature to 400 DEG C, the heating rate is 20-40 DEG C / min; from 400 DEG C to 600 DEG C, the heating rate is 10-20 DEG C / min; at 600 DEG C, the holding time is 15-25 min; from 600 DEG C to the sintering temperature, the heating rate is 20-30 DEG C / min; at the sintering temperature, the holding time is 5-20 min; wherein the sintering temperature is 1000-1300 DEG C. The flat ceramic membrane is prepared by the preparation method of the flat ceramic membrane according to any one of claims 1-8.

5. The method of claim 1, wherein the ceramic membrane is a flat sheet ceramic membrane. ​ 6. The method of claim 1, wherein the ceramic membrane is a flat sheet ceramic membrane. ​ 7. The method of claim 1, wherein the ceramic membrane is a flat sheet ceramic membrane. ​ 8. The method of claim 2, wherein the ceramic membrane is a flat sheet ceramic membrane. ​ ​ ​ ​ ​ ​ ​ 9. A flat sheet ceramic membrane characterized by, ​

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