RU2070430C1 - Method of preparing filtering member - Google Patents

Abstract

FIELD: gauze filters for liquid and gas media. SUBSTANCE: invention relates to gauze filtering members mainly designed for ultra- and microfiltration in biotechnology, medicinal and other industries. Method includes treatment of inorganic gauze basis with a IV-VI group metal oxide sol and consequent drying and two-step thermal treatment, temperature of the first step being 200-600 C and that of the second step being by 300-500 C lower than melting point of gauze basis material. As a latter, stainless steel or nickel gauze, and as a sol, zirconium and titanium oxide sols may be used. EFFECT: improved procedure of filtering member preparation. 3 cl, 1 tbl, 3 dwg

Description

 The invention relates to the filtration of liquid and gaseous media through filtering elements based on meshes, mainly carrying out ultra- or microfiltration processes in biotechnology, food, medical and other industries.

A known method of obtaining a filter element for cleaning liquids and gases [1]
The closest technical solution is a method of manufacturing a filter element based on multiple processing of a material obtained by weaving synthetic monofilaments with a solution of polyvinylidene fluoride in dimethylacetamide followed by heat treatment at 170-180 ^o C for 25-35 min [2]
The known method has several disadvantages inherent in methods for producing filter elements based on organic materials: low mechanical, thermal and chemical resistance, as well as a limited limit on the ability to control the size and quantity.

 The main technical objective of the proposed method is to obtain a filter element that provides control of porosity and pore size (pore spectrum) in a wide range (100-0.1 μm), simplifies the manufacturing process of the filter element of various shapes (flat, tubular, coaxial, etc.) and any sizes.

The essence of the invention lies in the fact that the filter element is made of composite material as a substrate (base) using a mesh of inorganic material, for example, nets of various weaving made of stainless steel, nickel, molybdenum, etc. with a selective coating of metal oxide (s), for example, zirconium, titanium, niobium, hafnium and other elements of groups IV-VI, obtained by treating the base with a sol of applied metal oxide (selective coating), then subjected to air drying and degradation (decomposition) of the sol at a temperature of 200-600 ^o C for 15-60 minutes and heat treatment for 300-500 ^o C below the melting temperature of the substrate material for 10-60 minutes

 As a result of degradation of the sol and high-temperature heat treatment, the sol decomposes to form a thin, strong metal dioxide in the form of a film on the surface of the substrate. If necessary, the operation of applying the oxide coating can be repeated to obtain a given pore spectrum.

 In the patent and scientific and technical literature, no information sources were found containing a combination of features of the proposed formula and allowing to solve the problem.

 Example. One of the available methods is applied to a fat-free stainless steel mesh (ОХ18Н9Т, food grade) a zirconium oxide sol, for example by dipping the mesh into a sol, the zirconium content in the ash is from 50 to 350 g / l. In this embodiment, the original mesh with a cell of 96 x 96 μm was used.

Cell size after 3 cycles, application of a zirconium sol and heat treatment of 29 microns, gas permeability (nitrogen) Q 2313 • 1 • 10 ⁴ l / 4 atm • m ² ;
pore size after 6 cycles of 14 microns, gas permeability Q 1070 • 1 • 10 ⁴ l / 4 atm • m ² ;
pore size after 12 cycles of 2.5 μm, Q 27 • 1 • 10 ⁴ l / 4 atm • m ² ;
pore size after 19 cycles of 0.2 μm, Q 6 • 10 ⁴ l / 4 atm • m ² .

 Drying time in air is determined by the concentration of the initial sol of zirconium (or another metal). Drying for 2 hours is necessary for sols of small concentrations up to 100 g / l (a film of zirconium oxide of small thickness is formed), for sols with an increased concentration of 300-400 g / l, the drying time is up to 6 hours.

The mode of destruction of the sol (temperature and time) also depends on the concentration of the sol for sols of small concentrations (up to 100 g / l), a sufficient temperature of destruction of 200-250 ^o C for 15-20 minutes, for sols of high concentrations (300-400 g / l ) it is necessary to carry out the process at a temperature of 400-600 ^o C for 40-60 minutes

The regime of high-temperature heat treatment (T.O.) is determined by the melting temperature of the substrate material (mesh). For a mesh of material with a high melting point (above 1800-2000 ^o C), the heat treatment temperature is 450-500 ^o C lower material, at mp material below the specified heat treatment temperature is lower mesh base material at 300-400 ^o C, respectively, the exposure time at T.O. is 10-60 minutes The dependence of the parameters of the filter element on the frequency of treatment with sol is presented in the table.

 The table shows the dependence of the parameters (pore size, gas productivity) of the resulting filter element on the multiplicity of processing with sol.

 In FIG. 1-3 are photographs of the structure of the filter element (the original mesh, after 6- and 9-fold treatment with sol, respectively, 1, 2 and 3).

 The use of the above-mentioned known and distinctive features in the proposed method allows to obtain a new technical result, which consists in obtaining a filter element with predetermined pore sizes of a selective filter layer and with a wide range (100-0.1 μm), as well as in good fixation of the selective layer on a porous a substrate that allows multiple regeneration of filters by countercurrent or high temperatures. The filter elements can be given any geometric configuration. The high mechanical strength of the substrates used allows filtering at pressures up to 10 atm, which increases the productivity of the process.

Literature
1. Auto N 1570746, MKI B 01 D 39/10, 1988

 2. Auto N1666155, MKI B 01 D 39/16, 1989

Claims (3)

1. A method of obtaining a filter element on a mesh basis, comprising treating the base with a liquid chemical and subsequent heat treatment, characterized in that a mesh of inorganic material is used as the mesh base, a sol of metal oxides of groups IV-VI treated with a chemical is used the substance of the mesh base is dried, the heat treatment is carried out in two stages, the first of which at a decomposition temperature of the sol of 200 600 ^o C, and in the second stage at a temperature of 300 500 ^o C below the temperature Ure melting material of the mesh base.  2. The method according to claim 1, characterized in that a mesh of stainless steel or nickel is used as the mesh base.  3. The method according to claims 1 and 2, characterized in that the sols of zirconium and titanium oxides are used as the liquid chemical.

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