RU2698390C1 - Refractory concrete mixture - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, in particular, is used for lining of metallurgical units, for example, heavy-duty ladles, intermediate ladles, vacuum generators, for production of molded refractory materials by vibration casting, and so forth, operating at temperature of up to 1750 °C. Refractory concrete mixture contains electrocorundum, high-alumina cement, alumina, polypropylene fibre and modifying additive - polycarboxylate at following ratio of components, wt. %: high-alumina cement 3–6; reactive alumina 10–15; polycarboxylate 0.5–1.0; polypropylene fiber 0.5–1.0; electrocorundum with particle size of not more than 6000 mcm - balance.

EFFECT: technical result is improvement of resistance to thermal changes and, accordingly, improvement of strength characteristics at heat load.

1 cl, 3 tbl

Description

Technical field

The invention relates to the field of metallurgy, in particular, it is used for lining metallurgical units, for example, steel pouring ladles, intermediate ladles, vacuum cleaners, for the manufacture of molded refractories by vibration casting, etc., operating at temperatures up to 1750 ° C.

State of the art

A known refractory concrete composition (RF patent No. 2550626, С04В 35/66, publ. 05/10/2015), including a refractory filler based on aluminum oxide, high alumina cement, a complex additive, organic and / or metal fiber and modifying additives, and complex the additive consists of silica fume, chromium oxide and a finely divided alumina component, which is used as reactive alumina and / or corundum with a dispersion of not more than 0.063 mm and / or calcined alumina, taken in the ratio (1-3) :( 1-4) :( 6 -9), with the following content of components in the concrete composition, wt. %: refractory filler - 71-92, high alumina cement - 2-5, complex additive - 5-21, organic and / or metal fiber - 0.01-2, modifying additives - 0.1-1.1.

The disadvantage of the composition is the presence of toxic silica fume.

Known hydraulically hardening mass of corundum composition (RF patent No. 2247095, С04В 35/10, С04В 35/66, publ. 02/27/2005), including electrocorundum, high alumina cement, alumina and a modifying additive, and it contains a preliminary modifying additive synthesized material with an Al ₂ O ₃ content _of 45-55% and CaO 42-52% in the following ratio of components, wt. %: high alumina cement 2.5-5, alumina 18-25, modifying additive 1.5-3, electrocorundum - the rest.

The disadvantage is the low resistance to molten metal.

The closest analogue adopted for the prototype is a refractory concrete mixture (RF patent No. 2239612, С04В 35/101, СВВ 35/66, published on November 10, 2004) containing granular electrocorundum and a complex finely dispersed binder based on a mixture of high-alumina cement, finely dispersed alumina and plasticizing additives, the mixture contains silicon carbide and fine corundum as fine aluminum oxide in the following components, wt. %: granular electrocorundum fractions 6-3 mm 15-22, fractions 3-1 mm 8-20, fractions 1-0 mm or a mixture of fractions 0.5-0 mm and fractions 1-0.5 mm 13-27, silicon carbide 13-27, finely divided corundum 14-24, high alumina cement 7-16, plasticizing additive 0.03-0.55.

The disadvantage of the prototype is that the concrete mixture has corrosion resistance only to molten iron.

Disclosure of the invention

The technical result of the invention is to improve resistance to heat exchange and, accordingly, a large operating time of the metallurgical unit; improvement of strength characteristics under thermal load.

The technical result is achieved due to the fact that in a refractory concrete mixture, including electrocorundum, high alumina cement, alumina and a modifying additive, it is new that the mixture contains polypropylene fiber, and polycarboxylate as a modifying additive, in the following ratio of components, wt. %:

High Alumina Cement 3-6

Reactive Alumina 10-15

Polycarboxylate 0.5-1.0

Polypropylene fiber 0.5-1.0

Electrocorundum with a particle size of not more than 6000 microns - the rest.

Additional features contribute to the achievement of the technical result: the mixture contains reactive alumina with a particle size of not more than 10 microns.

The specified qualitative and quantitative ratios of the components of the proposed refractory concrete mixture are the most acceptable, since when you go beyond the claimed ranges of quantitative ratios of the components of the mixture the specified technical result is not achieved.

The implementation of the invention

Dry refractory concrete mixture consists of, by weight. %: white electrocorundum powder (EB) (Al ₂ O ₃ ) 80-90 with a particle size of not more than 6000 microns, reactive alumina 10-15 with a particle size of not more than 10 microns, modifying additives 0.5-1.0, as which is polycarboxylate, polypropylene fiber 0.5-1.0, and high alumina cement 3-6.

The amount of water for mixing, wt. %: 4-5.

The mechanical strength after firing is 180-210 MPa.

The mixture is prepared by mechanical mixing of the materials in the following sequence: first all EB components are averaged, then reactive alumina, high alumina cement, lastly polycarboxylate and polypropylene fiber are added under the following conditions: moisture is not allowed to enter the material to prevent its hardening.

For mixing, a mechanical mixer with a fixed body and a rotating internal paddle mixer is used.

Refractory concrete mix is supplied to the consumer in dry form, packaged in airtight packaging, in accordance with his requirement. The lining of the metallurgical unit is made at the consumer after the preparation of concrete mortar. The mixture is non-toxic, fire and explosion proof.

Case Studies

Prototypes No. 1, No. 2, No. 3, No. 4 of the proposed refractory concrete mix and the corresponding experimental numbers of refractory materials No. 1, No. 2, No. 3 and No. 4 were made in composition. The composition of the refractory concrete mixture is presented in table 1.

According to physico-chemical indicators and grain composition, the mixture must comply with the standards indicated in table 2.

The test results of refractory concrete are presented in table 3.

In order to evaluate the refractoriness of the experimental samples of concrete to melt, crucibles (concrete products No. 1, No. 2, No. 3 and No. 4) were made, filled with 3000-6000 μm refined silicon grains and placed in a muffle furnace under heating to 1750 ° C and holding for 6 o'clock. After the procedure, the crucibles were removed and inspected; there were no observations related to the passage of the melt on any sample. Further, the crucibles were sawn to inspect the inner walls of contact with silicon - no comments were found.

Compared with other analogues, the proposed refractory concrete mixture provides refractory concrete with the following improved characteristics:

1. Improved resistance to heat exchange and, accordingly, a large operating time ("running" campaign) of a metallurgical unit (~ 8.5% in terms of the number of heats).

2. The best strength characteristics under thermal load (1750 ° C):

- bending strength of 27.2 MPa;

- compressive strength 234.0 MPa.

3. The absence in the formulation of toxic silica fume used for high strength and corrosion-resistant concrete.

Claims (3)

1. Refractory concrete mixture, including electrocorundum, high alumina cement, alumina and a modifying additive, characterized in that the mixture contains polypropylene fiber, and polycarboxylate as a modifying additive in the following ratio, wt.%: High Alumina Cement 3-6 Reactive Alumina 10-15 Polycarboxylate 0.5-1.0 Polypropylene fiber 0.5-1.0 Particle size electrocorundum no more than 6000 microns rest 2. The mixture according to p. 1, characterized in that it contains reactive alumina with a particle size of not more than 10 microns.