RU2817169C1 - Method of making blowing tuyere from refractory mass - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to steelmaking and can be used to increase efficiency of metal treatment in a ladle with an upper refractory blowing tuyere. Method of making a blowing tuyere from a refractory mass involves installing a metal pipe with through holes in the lower part of the T-shaped mold into a template, sealing through holes, mixing the components of the refractory mass in a dry state, mixing with water and mixing, pouring the refractory mass into a template, followed by vibration treatment, hardening, holding in the template, removing the template, holding at ambient temperature. According to the invention, refractory concrete has the following chemical composition, wt.%: Al₂O₃ 50–60; CaO 1–5; SiO₂ not more than 49. Metal fiber is additionally used as component additives. After holding at ambient temperature, the refractory article in the form of a blowing tuyere is subjected to thermal treatment at temperature of up to 800 °C, followed by cooling to ambient temperature.

EFFECT: longer life of the upper refractory blowing tuyere, lower labor input when treating metal in the ladle due to increased durability and wear-resistance of refractory concrete.

1 cl, 1 ex, 2 tbl, 1 dwg

Description

The invention relates to the production of refractories and masses for lining elements of thermal units of metallurgy, in particular to steelmaking, and can be used to increase the efficiency of metal processing in a ladle with an upper refractory blowing lance.

Modern requirements for the quality of smelted steel establish the target content of impurity elements, based on the regulated content of impurity elements in the finished steel. For this purpose, metal refining is carried out in pouring ladles using an upper refractory blowing lance with the injection of powdered reagents.

The products of smelting when processed by the upper refractory blowing lance are refined metal and basic slag.

A high-temperature heat-insulating material is known [1] (USSR Author's Certificate No. 921461, MPK S04V 35/00, S04V 43/02 dated May 30, 1973), containing the ratio wt%: high-alumina cement 25-40; aluminosilicate fiber 15-55; aluminous filler 5-45.

The disadvantage of high-temperature thermal insulation material is the insufficient strength and fire resistance of the product.

A known raw material mixture for the preparation of refractory concrete [2] (USSR Author's Certificate No. 1823869, MPK S04V 35/10, dated 07/12/1991, published 06/23/1993), containing the component ratio wt %: high-alumina cement 20-25; magnesium hydroxide 0.2-5; aluminum powder 0.2-5; potassium permanganate 0.55-2.5, corundum filler - the rest.

The disadvantage of the raw material mixture is that it is difficult to manufacture; the resulting product does not meet the properties of slag resistance.

A fire-resistant concrete mixture is known [3] (RF Patent No. 2239612, MPK S04V 35/101, S04B35/66 dated March 19, 2003, published November 10, 2004 Bull. 31), containing the component ratio wt %: granular electrocorundum fraction 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 dispersed corundum 14- 24, high-alumina cement 7-16, plasticizing additive 0.03-0.55.

The disadvantage of the raw material mixture is the use of a coarse fraction up to 6 mm, which negatively affects the structure of the refractory product, increasing its porosity, and the use of expensive components such as silicon carbide.

The closest in its technical essence and achieved results to the proposed invention is a method for manufacturing products from a refractory mass [4] (RF Patent No. 2348595, IPC S04B 35/66, dated 01/09/2007, published 07/20/2008 Bulletin 7), comprising the following ratio of components, wt %: mullite-corundum mixture 45-60; high-alumina cement that has partially or completely lost its activity 18-26; liquid glass 20-24; hardener 2-6.

The disadvantage of this invention is the increased amount of cement used, which leads to a deterioration in the abrasive resistance of products and strength characteristics.

The technical result of the invention is to increase the service life of the refractory blowing lance, as well as to reduce labor costs when processing metal in a ladle by increasing the strength and wear resistance of refractory concrete.

This result is achieved by the fact that in the method of manufacturing a blowing lance from a refractory mass 1 containing refractory concrete and component additives, including installing a metal pipe 2 with through holes 3 in the lower part of the T-shape into a template, sealing the through holes 3, mixing the components in in a dry state, mixing with water and mixing, pouring the refractory mass 1 into the template, followed by vibration treatment, hardening, holding in the template, removing the template, holding, according to the invention, the components of the refractory mass 1 are used in the following ratio, wt. %: Al ₂ O ₃ - 50-60; CaO - 1-5; SiO ₂ - no more than 49, and exposure is carried out at ambient temperature.

In addition, metal or organic fiber is used as component additives.

In addition, after exposure at ambient temperature, the refractory product in the form of a blowing lance is subjected to heat treatment at temperatures up to 800°C, followed by cooling to ambient temperature.

The limits for the content of components in the claimed invention were obtained experimentally.

The use of refractory concrete in the manufacture of refractory masses in the ratio of components mass%: Al ₂ O ₃ 50-60, CaO 1-5, SiO ₂ no more than 49 leads to an increase in the service life of the upper refractory blowing lance, and also makes it possible to obtain uniform wear over the entire height of the blowing tuyere tuyeres.

According to the invention, the refractory mass has the following quantitative composition (wt.%) and qualitative composition:

the content of Al ₂ O ₃ in the range from 50 to 60%, with the declared ratio of other components of the refractory mass, determines its strength and increases the number of heating-cooling cycles. A reduction in content of less than 50% leads to a decrease in performance properties. An increase in the Al ₂ O ₃ content by more than 60% leads to an increase in the price of the product;

CaO content ranging from 1 to 5%, with the stated ratio of other components of the refractory mass, is necessary for abrasive resistance. If the CaO content is less than 1%, there will be no obvious improvement in physicochemical characteristics. An increase in CaO content of more than 5% leads to a decrease in strength characteristics;

the SiO ₂ content is not more than 49%, with the declared ratio of other components of the refractory mass, is slag resistance. When the SiO ₂ content is less than 49%, it is necessary to increase the alumina content in the refractory mass, which will lead to an unreasonable increase in the cost of the product. An increase in the SiO ₂ content to more than 49% will lead to a deterioration in slag resistance and a decrease in the fire resistance of the refractory mass.

The claimed technical result is achieved using the quantitative and qualitative composition of the components, and does not depend on the sequence (order) of their addition to the mixture.

To impart rigidity to the finished product in the form of a blowing lance, metal fiber is used as part of the refractory mass.

To impart rigidity to the finished product in the form of a blowing lance, organic fiber is used in the composition of the refractory mass.

Heat treatment of the finished product in the form of a blowing lance at temperatures up to 800°C, followed by cooling to ambient temperature after exposure at ambient temperature, helps remove physical and chemically bound water. When the heat treatment temperature increases above 800°C, it increases the cost of the product and reduces the strength characteristics of the product.

The essence of the invention is illustrated in Figure 1.

where 1 is refractory mass;

2 - metal pipe;

3 - through holes.

Examples of using

Example 1.

According to the invention, the refractory mass was subjected to tests carried out in the converter shop of EVRAZ NTMK JSC to determine physicochemical parameters.

The component composition of the refractory masses used for the blowing lance is given in Table 1.

Table 1 Composition no. Content of element oxides, % Al ₂ O ₃ ,% CaO, % _SiO2 ,% 1. 62.5 2.5 35.0 2. 53.1 3.0 43.9 3. 45.5 6.0 48.5

The essence of the operation was that the refractory mass 1 for the blowing lance (Fig. 1) was produced as follows: in the proposed ratio, the components of the refractory mass 1 from the bin system entered the concrete mixer, where at the initial time they were mixed in a dry state for 2 minutes, then the components were mixed with water, metal fiber was added to the composition to impart rigidity to the product, the components were continuously mixed for 5-10 minutes, the finished concrete was poured into the template and, using a vibrating table, evenly distributed over the entire cross-section of the product. In this case, the template for pouring from the inside was pre-lubricated with an oil-containing material to prevent concrete from sticking to the walls of the template. The product was kept in the template for about 24 hours at ambient temperature to harden the refractory mass 1, then the template was removed and the product was kept in the form of a blowing lance for 24 hours, after which the product in the form of a blowing lance was subjected to heat treatment with heating to 800°C for two - three days, followed by slow cooling after completion of heat treatment to ambient temperature.

All samples were subjected to various physical and mechanical tests. The test results are presented in Table 2.

table 2 Composition no. Tensile strength, N/mm ² Open porosity, % Apparent density, g/cm ³ prototype 50 20 1.99 1. 110 15.5 2.53 2. 100 15.6 2.35 3. 60 19.0 2.31

From Table 2, it is clear that the refractory mass for the blowing lance according to option 1 has better characteristics of increased strength and density, therefore, increased abrasive resistance to slag in comparison with the blowing lance according to option 3. However, as previously stated, the manufacture of a blowing lance according to Option 1 leads to an increase in the price of the product.

The best method in terms of manufacturing cost and performance characteristics is the method of manufacturing the blowing lance according to option 2.

Thus, the essence of the claimed technical solution lies in the fact that the components of refractory concrete Al ₂ O ₃ , CaO, SiO ₂ are selected in the optimal ratio, which ensures an increase in the service life of the refractory blowing lance, due to the proposed composition of refractory concrete, allowing for uniform wear across the entire height of the blowing lance.

Analysis of patents and scientific and technical information revealed the absence of features similar to those inherent in the proposed technical solution, which allows us to conclude that it meets the “inventive step” criterion.

From the studies carried out it follows that the use of the declared refractory mass for the blowing lance makes it possible to ensure:

1. increase in the service life of the blowing lance by at least 20%;

2. reduction of labor costs when processing metal in a ladle by 25%;

3. increasing the strength of the refractory mass by 45%;

4. increasing the wear resistance of refractory concrete by 10%.

Experimental development and use of the proposed technical solution at EVRAZ Nizhny Tagil Metallurgical Plant JSC confirms compliance with the criterion of “industrial applicability of the invention.”

Information sources

[1] Copyright certificate of the USSR No. 921461, IPC S04V 35/00, S04V 43/02 dated May 30, 1973”;

[2] Copyright certificate of the USSR No. 1823869, IPC S04V 35/10, dated July 12, 1991, published. 06/23/1993;

[3] RF Patent No. 2239612, IPC S04V 35/101, S04V 35/66 dated 03/19/2003, published. 11/10/2004 Bulletin 31;

[4] RF Patent No. 2348595, IPC S04V 35/66, dated 01/09/2007, published. 07/20/2008 Bulletin 7.

Claims (6)

1. A method for manufacturing a blowing lance for refining metal in a ladle, including installing a metal pipe with through holes in a template, sealing the through holes, preparing refractory concrete by mixing the components in a dry state, mixing them with water and mixing, pouring it into the template, followed by vibration, holding in a template, removing the template, characterized in that they use refractory concrete, which has the following chemical composition, wt.%: Al ₂ O ₃ – 50-60; CaO – 1-5; SiO ₂ – no more than 49, Moreover, after pouring refractory concrete into the template with subsequent vibration, the refractory product is kept in the template at ambient temperature for 24 hours, and after removing the template, the refractory product in the form of a blowing lance is kept at ambient temperature for 24 hours, after which it is subjected to thermal processing at temperatures up to 800°C for no more than 48 hours, then cooled to ambient temperature. 2. The method according to claim 1, characterized in that metal fiber is used as an additional component of refractory concrete.