EA004725B1 - Ceramic filtering element and method for producing said element - Google Patents

Abstract

1. A ceramic filtering element, comprising a filtering frame (1) with filtering and inner surfaces, the frame is made in the form of an annular sector from porous ceramics with opened pores, the size of which increases in a direction towards the filtrate output, inner elements (2) and walls (3) forming a hollow cavity, and a neck with an outlet branch (5), characterized in that the filtering frame (1) is formed by spherical particles (6) of electrocorundum having the ratio of sizes thereof which varies in a direction towards the filtrate output, the internal elements are disposed in parallel rows in two reciprocally perpendicular directions, each element comprising two truncated cones which are embodied in the form of an integral part of the frame and connected to each other by the surfaces of the cross section thereof. 2. The ceramic filtering element of claim 1, characterized in that the ratio of size particles of the filtering surface to the size particles of the inner surface is 0.02-0.05. 3. A method for producing a ceramic filtering element comprises the steps of preparing a plastic mass including electrocorundum and a clay-containing component, forming a chemical composition of a porous carrier and a technological binder, forming compounds of the porous carrier, drying and sintering, applying suspension for forming a membrane layer and thermal treatment, characterized in that the step of introducing the M40 electrocorundum, a bentonite and a sulphate-alcohol mash - CAM in the form of a technological binder into a plastic mixture, two compounds of a porous carrier are pressed during formation in such a way that they are mirror-imaged and sintered at a fusion temperature of the bentonite, prior to assembling, the mounting planes of the thus produced elements are worked out and the gluing components are applied thereto and for forming the membrane layer the suspension is used, comprising the M3 or M5 electrocorundum as a filler and a chromo-phosphate-alumina binder, drying is carried out at an ambient temperature and thermally treated providing completion of interacting process of the chromo-phosphate-alumina binder with the filler and the porous carrier. 4. The method of claim 3, characterized in that the plastic mass comprises components in the following ratio, wt %: M40 electrocorundum 65 - 78, Bentonite 10 - 30, Sulphate-alcohol mash 5 - 12. 5. The method of claim 3, characterized in that the final product is thermally treated at +300+-50 degree C.

Description

Technical field

The invention relates to the field of filtering devices, in particular, to the design of filter elements of disk ceramic filters and methods for their manufacture, and can be used in the design and manufacture of disk ceramic filters for filtering pulps of enrichment products at mining and processing plants and wastewater from galvanic plants.

State of the art

A circular ceramic filter sector is known, including a hollow shell, the inner volume of which is filled with granular elements, and the walls of the shell and granular elements are made of material ~ 55% A1 ₂ O ₃ , 40% δίθ ₂ and 5% CaO with a particle size of 0.002 mm and have uniform distributed porosity with a pore size of 0.0010 to 0.0015 mm, with a ratio of length to shell thickness of more than 30, and a ratio of length to wall thickness of the hollow shell is over 120 (German patent, No. 3641057 C2, MKI C 04B 38/00; At 01Ό 46/10, priority from 12/01/86, opu glare 04/16/98).

A disadvantage of the known device is the low productivity of the cake, due to the fact that the filtrate is removed from the pulp at the points of contact of the granular aggregates with the inner plane of the shell to a lesser extent than in places free of these contacts, and filling with granular elements creates additional hydraulic resistance. In this situation, the filter layer has a significant spread of permeability, which reduces the set of cake on the filter surface.

By technical nature, the closest to the proposed device is a ceramic filter element containing a filter frame with a filter and inner surfaces, made in the form of a circular sector of porous ceramic with open pores, the dimensions of which are increasing in the direction of the filtrate outlet, the internal elements forming a hollow volume, and a neck with a discharge pipe (Ukrainian patent No. 41623 A, MKI B01 Ό 29/00, C04 B 38/00, dated November 14, 2000).

A disadvantage of the known device is that the intersecting channels form internal elements forming a hollow volume, which practically do not participate in the filtering process, creating “dead” zones, which lead to a decrease in the permeability of the ceramic body along the filter surface and, as a result, throughput on the cake.

A known method of manufacturing a ceramic filter element, including the preparation of a plastic mass containing components that form the chemical composition of the material of the porous carrier, and a technological binder, molding the constituent parts of the porous carrier, drying and sintering, assembling, applying a suspension to form a membrane layer, drying and heat treatment ( ΌΕ 3641057 C2, class C 04В 38/00, С 04В 38/08, В 01Ό 46/10, 1998).

The disadvantage of this method is that when slip casting in gypsum molds, the thickness and speed of the membrane layer is determined by the total porosity, its distribution and pore size of the gypsum mold, and in the case of hollow products can hardly be controlled. This leads to a difference in thickness of the membrane layer and a change in hydraulic resistance in local areas of the product. An identical effect is caused by the operation of filling the internal volume with elements of a porous carrier, as a result of which there is an uncontrolled laying of elements of a porous carrier with a different contact surface with the membrane layer. As a result of firing in these areas, sintering of the material of the porous support and the membrane layer occurs, which structurally leads to an increase in the size of the filter layer and hydraulic resistance by several times. In this situation, the membrane layer has a significant variation in permeability and physico-mechanical properties in the volume of the filter element, which reduces the quality of the product as a whole.

By technical nature, the closest to the proposed method is a method of manufacturing a ceramic filter element, including the preparation of a plastic mass containing electrocorundum and a clay component that form the chemical composition of the material of the porous carrier, and a technological binder, molding the constituent parts of the porous carrier, drying and sintering, applying a suspension for the formation of the membrane layer and heat treatment (patent 8I No. 1661167 A1, class C 04B 38/00, 03.10.88).

However, the known method of manufacturing a filter element in many cases does not allow to obtain uniformity of the porous structure of the layer. The membrane layer is susceptible to the formation of network defects due to shrinkage during drying and sintering, depending on the concentration of liquid in the suspension and the compatibility of the shrinkage of the porous carrier and the membrane layer. This results in reduced device performance.

Disclosure of invention

The basis of the invention is the task of developing the design of a filtering ceramic element with increased productivity, as well as a method for its manufacture, which ensures the elimination of heterogeneities in the volume of the filtering element, reducing the hydraulic resistance of the filtering layer and, as a result, increasing the productivity of the ceramic filtering element.

To solve the technical problem in a ceramic filter element containing a filter cage with filtering and internal surfaces, made in the form of a circular sector of porous ceramic with open pores, the dimensions of which are made increasing in the direction of the filtrate outlet, the internal elements and walls forming a hollow volume, and a neck with a discharge pipe, according to the invention, the filter frame is formed by sphere-shaped particles of electrocorundum with a varying ratio of their sizes in n in the direction of the filtrate outlet, and the internal elements are arranged in parallel rows in two mutually perpendicular directions and each of them consists of two truncated cones made integrally with the filter frame on the base and interconnected along the surfaces of their cross-section, in addition, the ratio of the size of the particles of the filter surface to size particles of the inner surface may be equal to 0.02-0.05.

In addition, to solve the technical problem in a method of manufacturing a ceramic filter element, which includes preparing a plastic mass containing electrocorundum and a clay component that form the chemical composition of the material of the porous support, and a technological binder, molding the constituent parts of the porous support, drying and sintering, applying a suspension for the formation of the membrane layer and heat treatment according to the invention, at the stage of preparation of the plastic mass, M40 electrocorundum, bentonite and as a technological bond, a sulfate-alcohol mash-SSB, during molding, two components of a porous carrier with a mirror image are pressed and sintered at a melting point of bentonite, before assembly, the obtained components are processed along the landing planes, adhesive components are applied to the landing planes, and during formation of the membrane layer, a suspension is used that contains M3 or M5 electrocorundum and an aluminum-chromophosphate binder as a filler; drying is carried out at room temperature and heat It is activated at a temperature that ensures the completion of the processes of interaction alyumohromfosfatnogo binder with filler material and porous carrier, moreover, during the preparation of the plastic mass M40 corundum, bentonite and PRS used in Content, wt.%

Electrocorundum M4065-78

Bentonite 10-30

SSB5-12 and heat treatment is carried out at a temperature of + 300 ± 50 ° C. The essence of the invention according to the proposed device lies in the fact that the implementation of the ceramic filter element in the manner described above allows for the formation of laminar outflow of the filtrate in the hollow volume of the sector and to intensify the process of cake deposition and filter regeneration.

The essence of the claimed technical solution according to the proposed method is that the implementation of the proposed method according to the above sequence of operations allows to obtain a ceramic filter element with a given porosity, strength and with increased filtration capabilities.

Brief Description of the Drawings

In FIG. 1 shows a ceramic filter element obtained by the claimed method; in FIG. 2 - section along aa.

The best embodiment of the invention

A method of manufacturing a ceramic filter element includes the preparation of a plastic mass containing components that form the chemical composition of the material of the porous support, and a technological bond, molding of the constituent parts of the porous support, their drying, sintering and assembly.

Next, the suspension is applied to form a membrane layer, drying and heat treatment.

A feature of the invention is that at the stage of preparation of the plastic mass, M40 electrocorundum, bentonite are introduced into it and, as a technological bond, a sulfate-alcohol mash - SSB with the content of components, wt.%

Electrocorundum M4065-78

Bentonite 10-30

SSB5-12

During molding, two components of a porous mirror-shaped carrier are pressed, which are sintered at the melting temperature of bentonite. Before assembly, the resulting components are processed along the landing planes, glued components are applied to the landing planes, and when the membrane layer is formed, a suspension containing M3 or M5 electrocorundum and an aluminum-chromophosphate binder is used as a filler. Drying is carried out at room temperature and heat treated at a temperature that ensures completion of the processes of interaction of the aluminochromophosphate binder with the filler material and the porous carrier.

The temperature ensuring completion of the processes of interaction of the aluminochromophosphate binder with the filler material and the porous carrier is in the range

300 ± 50 ° C. In this case, the formation of the necessary chemical bonds, an increase in adhesion, and, as a result, an increase in the shear strength between the membrane and the porous support, take place.

An example of the method

1. For the manufacture of products were used source materials:

1.1. Electrocorundum M3, M5, M40.

1.2. Bentonite.

1.3. Sulphate-alcohol mash (CSP).

1.4. Alumochromophosphate binder (AHFS).

2. M40 electrocorundum, bentonite and CSP with a percentage of components of 70: 23: 7, respectively, were placed in a mixer and the mixture was homogenized for 30 minutes.

The resulting plastic mass was coagulated by sieving through a 1 mm sieve.

3. The estimated amount of molding material was placed in a releasable mold and pressed at a specific pressure of 50 kg / cm ² . As a result of the displacement of the punch by a fixed value, preforms of the porous support of a given size and configuration were obtained.

4. The blanks were kept at room temperature for 24 hours and placed in a dryer. The drying temperature was maintained within 75 ± 5 ° C, and the isothermal exposure was 12 hours.

5. Dried preforms with a residual moisture content of 0.1-0.2% were placed on carborundum plates and fired, i.e. sintering at a temperature of 1250 ± 50 ° С with isothermal exposure for 2 hours. The billets after annealing were subjected to visual inspection for deformations, chips, and cracks. Conditioned experimental samples were examined for density, porosity, water permeability, strength according to standard methods. In the table. Figure 1 shows the characteristics of the material of the samples, obtained as arithmetic average of ten measurements — fragments cut from whole preforms of porous carriers. The data table. 1 show that the proposed method allows to obtain a stable structure of the materials of the porous support with minimum confidence intervals in physical and mechanical characteristics, which guarantees the elimination of inhomogeneities in the material and in the volume of the porous support, which ensures the quality of the products obtained.

6. Sintered billets were processed along the landing planes on a surface grinding machine, using diamond wheels on a copper binder grade АС12 400/312 with a particle size of M ₂ -01-150.

7. As the adhesive material applied to the landing planes, a dispersion mixture was used, consisting of M5 electrocorundum powder and alumochromophosphate binder, at a ratio of 50:50. The inside of the porous ceramic carrier was covered with a cardboard stencil so that the seating surfaces remained open. An adhesive mixture was applied with a spray gun and a second ceramic support was applied with a mirror image of the landing planes. The assembly was kept at room temperature and membrane layer material was applied to open work surfaces.

8. For applying the membrane layer, a disperse system was used containing 65% M3 electrocorundum and 35% AHPS. After thorough homogenization in the mixer for 40-50 minutes, the dispersed system was applied by spraying on the working surface of a porous ceramic carrier. It was experimentally established that exposure to air for 20-24 h makes it possible to obtain reliable adhesive adhesion with a shear strength of ~ 3-4 MPa, which guarantees the transportation of the workpiece without violating its integrity for the firing operation.

9. As a result of preliminary studies, the dependence of the change in the adhesion shear strength of the membrane layer on the surface of the porous ceramic carrier depending on the heat treatment temperature was revealed. Based on the obtained dependences, heat treatment was carried out in the temperature range 300 ± 50 ° С.

As a result of exposure at a temperature of 300 ° C for 10-15 h, the membrane was fixed on a porous ceramic carrier with a shear strength of 13 ± 2 MPa. With increasing temperature, the shear stresses decrease monotonically.

10. The resulting porous ceramic filter elements after heat treatment were subjected to visual inspection and tests according to standard methods. Visual inspection did not reveal distortions in geometric form, with an increase of "40" times on the surface of the membrane no defects were detected in the form of delamination, cracks or swelling. There are no delamination between the two components of the porous support, the seam is barely visible.

11. The data table. 2 show that the proposed method allows to obtain competitive filtering elements, and the strength characteristics and throughput of the elements can increase the working pressure of the filtration and the performance of the filtering systems as a whole.

The heat treatment process at temperatures to obtain the maximum strength bonds of the membrane layer with a porous carrier ensures the completion of the interaction of the aluminochromophosphate binder with the filler material and the porous carrier,

Ί which leads to the formation of chemical bonds, increased adhesion and, as a result, to an increase in shear strength between the membrane and the porous support.

The ceramic filter element contains a filter frame 1 with a filter (external) and internal surfaces, made in the form of a circular sector of porous ceramic with open pores, the dimensions of which are made increasing in the direction of the filtrate outlet, internal elements 2 and walls 3, forming a hollow volume 4, and throat with outlet 5.

The filter frame 1 is formed by sphere-shaped particles 6 of electrocorundum with a varying ratio of their sizes in the direction of the filtrate exit.

The internal elements 2 are arranged in parallel rows in two mutually perpendicular directions, and each of them consists of two truncated cones made integral with the filter frame 1 at the base and interconnected along the surfaces of their section.

The ratio of the particle size of the filtering surface to the particle size of the inner surface is 0.02-0.05.

The internal section of the pipe 5 is designed so that it allows you to display in a unit time the volume of liquid is not less than the volume of the filtrate entering the hollow volume.

The design of the material of the walls of the filter frame 1 from high-density spherical particles 6 of electrocorundum eliminates additional deadlock and open porosity, which reduces the roughness of the walls of the permeable pores and minimizes the internal hydraulic resistance of the filter housing 1.

The choice of the range of the ratio of particle sizes 6 of the filter surface to the particle size of the inner surface of the filter frame 1, equal to 0.02-0.05, due to the following reasons.

When the ratio is less than 0.02, cake productivity decreases, and when the ratio is more than 0.05, cake humidity increases, which requires additional drying costs.

In addition, under the selected boundary conditions of the particle size ratio 6, the principle of the Loval nozzle is implemented in each subsequent minimum layer of the filtering volume, which, in turn, leads to a decrease in hydraulic resistance in the direction of the filtrate exit.

The internal elements 2 provide the rigidity of the filter frame 1 and lead to an increase in structural strength, and their configuration and increased pore size form a laminar outflow of the filtrate in the hollow volume of 4 sectors and intensify the filter regeneration process.

The arrangement of internal elements 2 in parallel rows in two mutually perpendicular directions forms a wave movement of the filtrate near the filtering surface of the frame 1, leading to uniform distribution of cake on the filtering surface and increase productivity.

The internal section of the outlet pipe is organized in such a way that the filtrate exit rate during laminar outflow implements the piston principle in a closed sector volume and additional vacuum is created between the external (filtering) and internal filtration surfaces.

The device operates as follows.

Using the outlet pipe 5, the ceramic filter element is attached to the hollow shaft of the filter unit, an analogue of which is published in patent BE 3641057 C2. The ceramic disc filter is composed of twelve ceramic filter elements. When the filter unit shaft is rotated, the ceramic filter element of the disk ceramic filter is partially immersed in the reservoir with the pulp for the substance to be filtered. As a result of suction through the hollow shaft, the filtration process begins through the porous filter frame 1 and the internal elements 2. The filtrate is collected in the hollow volume 4 formed by the porous filter frame 1, the internal elements 2 and the side walls 3. The incoming filtrate is removed through the outlet pipe 5, the cross section of which allows you to display in a unit of time the volume of liquid is not less than the volume of the incoming filtrate.

On the filtering surface of the frame 1, a solid precipitate is formed, which is removed by a scraper installed at the entry position of the ceramic filtering element into the tank. The ceramic filter element cleaned of sediment is operational during subsequent cycles of immersion in the reservoir for the substance that needs to be filtered.

As a result of repeated, cyclical use of a disk ceramic filter, a thin layer of filtered sediment is formed on the filter surface of the porous cage 1, which is not removed by a scraper. This layer increases the hydraulic resistance and reduces the performance of the device.

In this case, periodic regeneration of the filter surface of the porous filter cage 1 is carried out by back-flushing with regenerating components.

Through the outlet pipe 5 serves the regenerating component under excess pressure in the hollow volume 4.

The increased pore size at the inlet of the regenerating component has little effect on hydraulic flow resistance, and the main pressure is concentrated in areas located near the filter surface of the porous filter cage 1, which leads to an intensification of the regeneration process. During regeneration, the internal elements 2 act as stiffeners, increasing the strength of the structure as a whole.

After regeneration, the ceramic filter element is used in subsequent multiple cyclic operating conditions as part of a ceramic disk filter.

In the table. Figure 3 shows the comparative technological results of experiments on the filtration of pulp of copper concentrate, particle size 9091% minus 44 microns in identical conditions.

Comparative tests have shown that the use of the proposed device in comparison with the known one allows to increase productivity by 2-2.5 times with identical cake moisture.

The characteristics of the material of the porous media

Table 1

Total porosity % Permeable porosity,% Medium hydraulic. pore diameter, microns Strength ^ SJ? MPa Water permeability, k, pm ² 47 ± 2 45 ± 2 30 ± 3 65 ± 5 18 ± 1

table 2

Way Filter layer thickness Medium hydraulic. membrane pore diameter, microns Strength ^ SJ, MPa Average filter performance, l / m ² -h Min the size of the retained fraction, microns Proposed 3500 1,5-2 65 ± 5 1050 2 Prototype 3500 1-1.5 13-3 280 2

Table 3

Index Food measuring Prototype Suggestions tech. decision Particle size ratio 0.02 0,035 0.05 one 2 3 4 5 6 Cake thickness mm 1.7 4.1 4.6 5.3 Humidity % 12.1 11,4 11.8 12.0 After regeneration: Cake thickness mm 2.1 4.6 4.9 5.5 Humidity % 11.5 11.3 11.5 12,4

Industrial applicability

The proposed method and device can be widely used in the mining industry in the manufacture of ceramic disk filters designed for filtering pulps of enrichment products.

Claims (5)

CLAIM 1. Ceramic filtering element containing filtering frame (1) with filtering and internal surfaces, made in the form of a circular sector of porous ceramics with open pores, the dimensions of which are made increasing in the direction of filtrate exit, internal elements (2) and walls (3) forming a hollow volume, and a throat with a discharge pipe (5), characterized in that the filter frame (1) is formed by spherical particles (6) of electrocorundum with a changing ratio of their sizes in the direction of exit of the filtrate And internal elements (2) arranged in parallel rows in two mutually perpendicular directions and each of them consists of two truncated cones, formed integrally with the filter frame (1) on the base and interconnected at their cross section surfaces. 2. Ceramic filter element according to claim 1, characterized in that the ratio of the particle size of the filter surface to the particle size (6) of the inner surface is 0.02-0.05. 3. A method of manufacturing a ceramic filter element, including the preparation of plastic mass containing electrocorundum and clay-containing component, forming the chemical composition of the material of the porous carrier, and technological bundle, forming the porous carrier components, drying and sintering, applying a suspension to form a membrane layer and heat treatment, characterized by the fact that at the stage of preparing the plastic mass, electrocorundum M40, bentonite and, as a technological binder, sulfate-alcohol are introduced into it During the molding process, two components of a porous carrier with a mirror image are pressed and molded at the melting temperature of bentonite. Before assembly, the resulting components are processed along the seating planes, adhesive components are applied to the seating planes, and in the formation of the membrane layer, a suspension containing as a filler, electrocorundum M3 or M5 and an aluminum-chromophosphate binder, drying is carried out at room temperature and thermally treated at a temperature ensuring complete s the interaction processes of an alumina-chromophosphate binder with a filler material and a porous carrier. 4. The method according to claim 3, characterized in that the plastic mass contains components in the following ratio, wt.%: Electrocorundum M4065-78 Bentonite 10-30 PRS5-12 5. The method according to claim 3, characterized in that the heat treatment is carried out at a temperature of + 300 ± 50 ° C.