RU2390513C2 - Refractory ramming mixture for refractory lining - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of refractory materials and can be used in metallurgy and other industries for making rammed linings for different high-temperature assemblies, mainly electric smelting furnaces. The proposed refractory ramming mixture contains dry sand, ground up clay, liquid glass M=2.8, and 30% caustic soda solution γ=1.32 g/cm³, as well as a refractory additive of a product of thermal decomposition of hydrogen-containing material with the following ratio of components in wt %: ground up clay 2-3, caustic soda γ=1.32 g/cm³ 0.9-1.5, liquid glass M=2.8 5.5-7, product of thermal decomposition of hydrogen-containing material 0.8 of liquid glass, dry sand - the rest. The product of thermal decomposition of hydrogen-containing material has particle size of 9-600 nm.

EFFECT: increased resistance of rammed linings of metallurgical electric smelting furnaces to molten metal and alloys at operating temperature of 1650-1800°C, use of cheap and ecologically clean materials, improve workability of the refractory ramming mixture due to its increased plasticity, as well as wider field of use.

2 cl, 1 ex

Description

The invention relates to the field of production of refractories and can be used in the metallurgical and other industries for the manufacture of printed linings of various high-temperature units.

Known refractory ramming mass containing a mixture of granular corundum FR. 1-3 mm and fr. 0.5-1.0 mm, taken in the ratio (4.5: 1) - (5.5: 1), a mixture of fine corundum in an amount of 91-95 wt.% And refractory clay in an amount of 5-9 wt.% with a content in the mixture of particles less than 50 microns in size not less than 50% and more than 63 microns in size no more than 20% and phosphoric acid in the following ratio of components, wt.%: a mixture of granular corundum 51-61, a mixture of finely divided corundum and refractory clay 32-43 phosphoric acid 5.5-7.5. As a mixture of finely divided corundum and refractory clay, their mechanical mixture or a mixture of co-grinding is used. The mass provides a decrease in open porosity, an increase in the strength and refractory properties of the linings obtained on its basis, as well as an increase in its workability due to an increase in ductility (RF patent No. 2256631, IPC: С04В 35/66, op. 2005.07.20).

The known refractory mass has a high slag resistance and after heat treatment at 1500 ° C is characterized by an open porosity of 16.0-16.9% and a compressive strength of 83.5-91.2 MPa.

However, despite the relatively high level of physical and ceramic properties, the use of this mass is limited due to insufficient strength after drying. As a binder, it contains phosphoric acid, which makes it harmful from an environmental point of view.

Also known is a refractory packing material for sand packing, which is used to make stuffed linings of steel pouring ladles and contains 5.95-8.50 wt.% Phosphoric acid, 7-12 wt.% A mixture of refractory clays of high and low ductility, taken in the ratio ( 1.0: 1.5) - (1.5: 1.0), 0.05-0.50 wt.% Alkylsiliconate and high alumina component as the rest (USSR AS No. 1447792, С04В 28/34, 1988 - prototype ) The refractory mass is prepared in a mixing unit, first loading a granular high-alumina component, which is a filler, then an orthophosphoric acid solution with a density of 1.3-1.4 g / cm and then, together with an alkyl siliconate, a finely ground component containing a mixture of finely dispersed refractory clays of high and low ductility and finely divided alumina component.

Despite the relatively high percentage in this refractory mass of not just refractory clay, but a mixture of refractory clays of high and low ductility, it is characterized by insufficiently high ductility, which, when stuffed, does not make it sufficiently workable. At the same time, a high percentage of refractory clay leads to the fact that linings based on it have a sufficiently high open porosity, which, after drying and calcination, is 18-20% and 22-24%, respectively, with a relatively low compressive strength after calcination, which is no more than 71-80 N / mm ² , and not high enough deformation temperature under load, characterized by a temperature of four percent compression of not more than 1600 ° C. As a binder, it also contains phosphoric acid, which makes it harmful from an environmental point of view.

The problem to which the invention is directed, is to increase the resistance of the printed lining of metallurgical electric melting furnaces to molten metals and alloys at service temperatures of 1650-1800 ° C, the use of cheap, environmentally friendly materials, to increase the workability of the refractory packing material by increasing its ductility, as well as expanding the scope.

The technical result that can be obtained by using the invention is to increase the density, strength and metal resistance of the lining, maintainability of the lining with this mass, as well as to increase the safety of operation of furnaces.

To solve this problem, a refractory packing material was proposed for lining predominantly metallurgical electric melting furnaces based on a refractory filler and hardener, which contains dry sand, ground clay, liquid glass M = 2.8 as a hardener, and 30% sodium hydroxide solution γ = 1.32 g / cm ³ , as well as a refractory additive in the form of a product of thermal decomposition of hydrocarbons (hereinafter - PTU raw materials) in the following ratio of components, wt.%:

ground clay 2-3 caustic soda γ = 1.32 g / cm ³ 0.9-1.5 water glass M = 2.8 5.5-7 Vocational school of raw materials 0.8 from liquid glass dry sand rest

PTU of raw materials is a product of thermal degradation of carbon-containing raw materials of brand P232 with particles of size 9-600 nm.

As a filler, it is allowed to take marshalit in the amount of 10% of sand. Marshalit (GOST 9077-82), which is powdered quartz, contributes to denser packing, pore reduction and better sintering.

The technical result is achieved due to the quantitative and qualitative composition of the mixture. Liquid glass, in comparison with other binders, has the highest adhesion to quartz, exceeding the strength of the grains themselves, and the PTU of the raw material, which has a highly dispersed structure with a highly developed surface with open chemical bonds, is evenly distributed over the grain surface, forming a dense, heat-resistant adhesive shell, significantly increases the refractoriness of the quartz itself.

Such a refractory mixture, having the property of workability by increasing its ductility, allows you to repeatedly repair the lining of a metallurgical electric melting furnace in a short time by lubricating the worked out areas of the lining, usually in the upper part of the furnace, ensuring high durability of the monolithic lining. The possibility of such repairs significantly reduces the cost of operation of metallurgical electric furnaces.

The feedstock for this refractory mixture is available, cheap, environmentally friendly.

The possibility of carrying out the invention is confirmed by the following examples.

Example 1

The composition of the refractory mixture was made, including ground refractory clay of grade P-1, P-2, TU 14-8-216-76, in an amount of 2.2%, 30% caustic soda solution γ = 1.32 g / cm ³ , GOST 2263-79, TD grade in the amount of 1.2%, liquid sodium glass for foundry M = 2.8, GOST 13078-81, in the amount of 6.54% and PTU of P232 raw materials with particles ranging in size from 9 to 600 nm in the amount of 0.8% of water glass, which is 0.05232% of the total mass of the composition, the rest is dry molding quartz sand of composition 2K ₂ O ₂ 02 according to GOST 2138-91.

The technological process of preparing the mixture is as follows.

The starting materials were loaded into the mixer in the following sequence. First, dry sand and clay were loaded and mixed for 4 minutes. Then 30% sodium hydroxide solution γ = 1.32 g / cm ^{3 was} added and mixed for another 2 minutes. Pre-vocational training of raw materials was thoroughly mixed with liquid glass to obtain a uniform mixture without sediment. After that, the resulting composition was added to the mixture and the whole was mixed for another 8 minutes.

To determine the physicomechanical properties of the refractory ramming mass, samples were made in the form of columns and eights. Tests of compressive strength were carried out according to GOST 4071.1-94. Tests have shown that the compressive strength is δ _cheese. amounted to 0.10-0.18 kg / cm ² and the compressive strength δ _dry. amounted to more than 20 kg / cm ² .

The moisture content of the lining mixture was 3–4%.

Thus, cheap, environmentally friendly materials are used for the manufacture of refractory packing material. It provides increased resistance of the printed lining to molten metals and alloys at service temperatures of 1650-1800 ° C. The refractory packing mass has the property of increased workability by increasing its ductility, which plays a significant role in the process of regular furnace repairs.

Claims (2)

1. Refractory packing material for lining predominantly metallurgical electric melting furnaces, containing refractory filler and hardener, characterized in that it contains dry sand, ground refractory clay, 30% caustic soda solution γ = 1.32 g / cm ³ and refractory additive PTU raw materials in the following ratio of components, wt.%:
ground clay 2-3 caustic soda γ = 1.32 g / cm ³ 0.9-1.5 water glass M = 2.8 5.5-7 Vocational school of raw materials 0.8 from liquid glass dry sand rest 2. The refractory ramming mass according to claim 1, characterized in that the PTU of the feed is a product of thermal degradation of carbon-containing feed with particles of 9-600 nm in size.