RU2379256C1 - Mixture for manufacturing of porous ceramics - Google Patents

Abstract

FIELD: construction engineering.

SUBSTANCE: mixture contains uniform filling aluminium oxide, bentonite in the form of magnesium or calcium montmorillonite and an organic vehicle - pale yellow, acidic, corn dextrin modified by the preparation OPTAPIX PAF 35 in the dry-basis ratio, wt %: aluminium oxide 84-89, bentonite 5-7, the organic vehicle 6-9, with the ratio of the organic vehicle dextrin to the preparation OPTAPIX PAF 35 within 1:1 to 1:2.

EFFECT: higher post-mould and dry durability, improved quality of porous ceramics.

2 cl, 2 tbl

Description

The invention relates to ceramic materials science, in particular to the production of porous permeable ceramics for the manufacture of ceramic filter elements.

The development of installations for the purification of hot gases with a temperature of 900-1000 ° C required the creation of filter elements with increased requirements for mechanical strength, gas permeability, their effective performance under the corrosive effects of acid or alkaline components of the exhaust gases.

Implementation of the requirements for filtering elements is carried out by using a mixture containing a filler of a certain fractional size, mineral binders forming a macro- and microstructure, and organic binders to impart mechanical strength to the semi-finished product, eliminating destruction under the action of deformation forces or dead weight during transport movements.

The ratio of the sizes of the filler fractions and the ceramic binder determines the volume content and distribution of pores, their hydraulic diameter, and the components of the ceramic binder form strength characteristics, and the crystal structures formed during the synthesis of porous permeable ceramics should ensure effective performance under conditions of exposure to corrosive media.

World practice shows that amphoteric alumina in its various modifications works effectively in acidic and alkaline environments and can be used as a filler to form the framework of a porous permeable ceramic material. Blends are known for producing a porous permeable ceramic material containing electrocorundum fillers using simple and complex oxide and silicate compounds and organic binders as a mineral bond (US 4302502 A, 11.24.1981; SU 1036704 A, 08.23.1983; DE 3641057, 16.06. 1988; US 5232598 A, 03.08.1993; RU 2204542 C1, 05.20.2003; RU 2182568 C2, 05.20.2002; RU 2288202 C1, 11.27.2006).

The disadvantages of porous ceramics from known blends are low values of permeable porosity and strength, and the resulting crystalline phases have low resistance to acid and alkaline environments at high operating temperatures.

The closest analogue of the claimed object for the technical task to be solved - the prototype - is the mass for the manufacture of porous filtering ceramics, including fractionated electrocorundum or chamotte, as the clay component is sodium montmorillonite and an organic binder in the form of dextrin or polyvinyl acetate binder in the following ratio of components, wt.%. :

The specified monofraction electrocorundum or chamotte, or their mixture in a ratio of 1: 1 69-78 Sodium Montmorillonite 21-30 Organic bunch 1-5

(SU 1654290 A1, class C04B 38/00, publ. 07/07/1991).

A disadvantage of the known mixture is that it contains an increased amount of clay component of bentonite in the form of sodium montmorillonite, which reduces the overall porosity of the material, operating temperature, and the synthesized phases have low resistance to acid and alkaline environments at high operating temperatures.

In addition, the type and amount of organic binder does not provide the transport strength of large-sized tubular blanks of gas filters with sizes L up to 1500 mm and wall thicknesses of the order of 3-3.5 mm obtained by hydrostatic pressing.

The objective of the invention is to develop a mixture for the manufacture of porous permeable ceramic material, ensuring the achievement of the purpose of the invention is to improve the quality of porous ceramic material.

This goal is achieved in contrast to the known charge in that it contains bentonite in the form of magnesium or calcium montmorillonite as a clay component, fawn acid corn dextrin modified with ORTARiX PAF 35 as an organic binder, with the following ratio of components to dry weight, wt. %:

Electrocorundum 84-89 Bentonite 5-7 Organic binder 6-9

moreover, the ratio of dextrin and the drug ORTARiX PAF 35 is from 1: 1 to 1: 2.

The essence of the claimed technical solution lies in the fact that the introduction of a filler in the form of monofraction electrocorundum makes it possible to obtain a porous skeleton with a uniform pore size in volume, the use of bentonite in the form of magnesium or calcium montmorillonite allows the formation of a ceramic binder during sintering with the formation of high-temperature crystalline phases of the spinel row having increased refractoriness above operating temperatures of the filter element, use in a binder preparation and ORTARiX PAF 35 provides a uniform distribution of the components of the mixture due to the formation of adhesion forces between the particles of raw materials, improves the compressibility of the mixture by reducing friction, increases the strength of the raw material after molding and drying, and the experimentally established concentration limits of the components in the mixture are necessary and sufficient to realize objectives of the invention.

An example of the manufacture of the charge.

For the manufacture of the charge were used raw materials:

Electrocorundum TU 3988-075-0022450-99 fraction 160-200 microns;

Bentonite Bulgarian TU - 3-94-08-658-86;

Dextrin corn acid fawn GOST 6034-74;

The drug ORTARiX PAF 35, which is a polyvinyl alcohol in the form of a 35% aqueous solution of the German company Zschimmer und Schwarz, is described in the article by Benito J.M. et al. Preparation and characterization of tubular ceramic membranes for treatment of oil emulsions, Journal of the European Ceramic Society 25 (2005), p. 1895-1903.

The commercially available raw materials were mixed in a Z-shaped mixer. Monofractional electrocorundum was wetted in the calculated amount on dry weight with ORTAPiX PAF 35 and, with subsequent constant stirring, powders of dextrin and bentonite were added.

After the introduction of the calculated quantities of the raw materials, homogenization mixing was carried out for 5-10 minutes.

Filter elements of a tubular type, a tube analogue, with a length size of 1000 ÷ 1500 mm, with D _H = 65 mm and a wall thickness of 3.5 mm, are formed from the resulting mixture. The molding is carried out by hydrostatic pressing at P _beats. = 90 ÷ 110 MPa. After removing the semi-finished product from the hydrostat, air drying is performed for 24 ÷ 28 hours. Firing is carried out in batch or tunnel furnaces at a temperature of 1300 ± 50 ° C for 4 hours. The characteristics of the blends and materials are presented in table 1, 2.

The presented comparative characteristics of the materials of the prototype and according to the proposed technical solution confirm the technical usefulness and achievement of the goal, as well as the competitiveness of the charge for the manufacture of ceramic permeable filter elements.

Table 1 Components The content of components, wt.% charge Charge 1 Charge 2 Charge 3 Prototype Electrocorundum 84 86.5 89 69 (160-200 microns) Bentonite 7 6 5 thirty Organic 9 7.5 6 one binder Ratio 1: 1 1: 1,5 1: 2 - dextrin for OPTAPiX PAF35

table 2 Characteristic Proposed Technical Solutions one 2 3 Prototype Pore size, microns 80 97 BY 75 Permeability, pm ² 87 106 120 75 Strength, MPa: after drying 37 ± 2,5 40 ± 2.5 47 ± 2,5 - after sintering 90 ± 1,5 80 ± 1.5 75≤1.5 52 ± 2,5

Claims (2)

1. The mixture to obtain a porous ceramic material, including monofraction electrocorundum, a clay component, an organic technological binder, characterized in that, as the clay component, the mixture contains bentonite in the form of magnesium or calcium motmorillonite, as an organic binder fawn, acid, corn dextrin, modified OPTAPiX PAF 35 in the following ratio of components to dry weight, wt.%:
Electrocorundum 84-89 Bentonite 5-7 Binder 6-9
moreover, the ratio of dextrin and OPTAPiX PAF 35 is from 1: 1 to 1: 2. 2. The mixture according to claim 1, characterized in that OPTAPiX PAF 35 is used as a 35% solution in water.