CS239236B1 - Permeabile refractory ceramic substance for filtration of non-ferous melt - Google Patents

Abstract

Permeable ceramic material for the production of filter fittings used for the filtration of non-ferrous metal melts and for the production of catalyst supports, characterized in that it consists of 85: 15 to 70: 30 in weight units of kaolinitic and expanded raw materials (70% to 85%) %) to 30 wt. % to 15 wt. polystyrene, urea, polyethylene, chloride or ammonium nitrate. Due to its low bulk density of 600 kg m ~ 5, the material can also be used as a heat-insulating refractory material.

Description

The present invention relates to a permeable refractory ceramic for non-ferrous metal melt filtration and catalyst supports.

The hitherto known refractory ceramics for non-ferrous metal filtration are produced using a quantity of egg matter to produce a continuous network of interconnected pores in the fired ceramic. The disadvantage of these filter materials is their low mechanical strength due to the sintering of these materials being limited by premature softening and deformation of the thin pores forming the pores. »Due to the low mechanical strength, the filter stones break up and crack.

Ceramic materials having a higher refractoriness and closed pores have higher mechanical strength. These materials, although very strong and porous, do not have the structure of permeable, transport pores and are therefore not usable as filter materials.

Also known are refractory ceramics according to U.S. Pat. 136 924, 136 931, 136 941 and according to AO no. 152 036, which are sufficiently strong and sufficiently refractory, but even these ceramic materials do not have permeable pores. A common feature of these compositions is that the pore structure is not a determining factor.

Ceramic mass according to ON 72 5910, also called microporous ceramics, is also known. This material has a permeable pore structure, but it is only usable up to 300 ° C and is not suitable for metal melt filtration and is also unusable as a catalyst support.

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These disadvantages are overcome by the invention, which relates to a permeable refractory ceramic mass, from which non-ferrous metal melt filtering elements and catalyst supports can be produced by conventional ceramic technology. It is also possible to produce thermally insulating building materials. The permeable refractory ceramic composition of the present invention consists of a mixture comprising 5% to 15% water (a), 30% to 60% by volume of some kaolinite raw materials selected from: float kaolin, halloysite, kaolinitic clay with a content of over 35% alumina (b) 10% by volume to 50% by volume of some expanded raw materials of the series with perlite, obsidian, volcanic tuff, vermiculite (c); polyethylene, urea, ammonium chloride, ammonium nitrate (d). The weight ratio of substances (a + b) to substances (c + d) amounts to 85 from 15 to 70: 30. by decomposition, a rigid porous permeable structure with transport pores at temperatures 300 ° C lower than the sintering temperature.

The advantages of the ceramic according to the invention are that it is possible to produce mechanically solid filter stones for, for example, the melt filtration of non-ferrous metals. By no other means can the melt intended for the casting of the critical components of the machines be removed from harmful impurities. It is known that no technically prepared metal is completely pure. It always contains undesirable admixtures, both from the technological process and from the raw materials used for lining, resp. crucible walls and combustion products, etc. Only a part of these impurities is removed together with the slag, but the remainder is transferred to the casting where it causes reject and operational unreliability of the product. The maximum purity of the melt is only achieved by filtering.

An advantage of the ceramic composition according to the invention is that it can be used for the production of catalyst supports and for the filtration of chemically aggressive gaseous and liquid substances. When the ceramic mass according to the invention is used for the production of heat-insulating refractory building materials, the advantage of this ceramic mass is its low bulk density of 600 kg per m.

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The embodiment of the invention is illustrated by two examples:

Example 1

A blend containing 50% by weight of floated kaolin, 20% by weight of expanded perlite having a grain size of 1mm to 2mm, 20% by weight of expanded polystyrene, 2mm to 3mm, and 10% by weight of water was mixed.

After drying and firing at 1400 C, it had a bulk density of 600 kg _e m < -1 >, a porosity of 80% and a compressive strength of 5 MPa. tested positively for aluminum melt filtration

Example 2

A blend containing 30% by weight granular urea, 10% by weight, expanded perlite 2 mm to 3 mm,% by weight float kaolin, and 10% blend water was formulated. The mixture was treated as in Example 1. of the composition of Example 1, but the mixture was more compressible.

Claims (1)

SUBJECT OF THE INVENTION 239 236 Permeable refractory ceramic for non-ferrous metal melt filtration and catalyst supports, characterized in that it contains from 5% to 15% by volume of water (a), from 30% to 60% by volume of some kaolinitioc raw material , halloysite, kaolinitic clay containing more than 35% alumina (b), 10% to 50% vol. I 'i obsidian, volcanic ash, vermiculite (c), and characterized further by containing 10% vol _. up to 40% by volume of a substance selected from foam polystyrene, polyethylene, urea, ammonium chloride, ammonium nitrate (d), the weight ratio of (a + b) to (c + d) being 85% by weight to 15% up to 70% by weight 30% by weight