RU2631570C2 - Complex steel oxidazer based on lumpy silicon carbide - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: lumpy silicon carbide (SiC) is used as material with a fraction more than 1 mm and moisture content less than 1% and its briquetted sifting of fraction less than 1 mm with final content in briquettes of basic element SiC 70-90%. Undersized SiC fractions less than1 mm briquetted with the use of beet molasses by vibrocompression into cylinders of up to 60 mm diameter and up to70 mm height or with the use of n inorganic binder with roller briquette press into tablets of up to 40 mm diameter and up to 30 mm height with strength of at least 400 kg/cm².

EFFECT: reduction of steel and cast iron production cost due to replacement of ferrosilicon with silicon carbide undersized fractions which surpasses ferrosilicon by technical characteristics.

3 cl, 6 tbl, 5 dwg

Description

The invention relates to ferrous metallurgy, and more particularly to smelting and after-furnace treatment (deoxidation, alloying and carburization) of steel and cast iron.

The prior art "Briquette used in the production of iron-carbon alloy (options)" (patent No. RU 2282669, C22B 1/243, C21C 1/00, C22C 38/00, 08/27/2006) refers to ferrous metallurgy, to the production of briquettes, used in the production of iron-carbon alloy. The briquette contains a silicon-containing material, a carbon-containing material and a binder. It contains metallurgical silicon carbide as a silicon-containing material, it contains heat-treated carbon-containing electrode material as a carbon-containing material, and cement as a binder. The invention will provide an increase in the strength characteristics of iron-carbon alloys and an improvement in the technological process for the production of castings from synthetic cast irons due to their simultaneous pre-carbonization and modification.

The technical task of this invention is to achieve a qualitative improvement in the composition of the briquette by replacing ferrosilicon with silicon carbide metallurgical at certain quantitative ratios of all components, which leads to higher technical results: increasing the strength characteristics of iron-carbon alloys, carburizing of a steel bath and improving the technological process for the production of steel and synthetic ( induction melting) and gray (cupola) cast irons due to their simultaneous carbonization, doping with silicon and modification.

The briquettes claimed by this invention (five options) can be used in the production processes of iron-carbon alloys, as well as steels, gray and alloy cast irons based on synthetic melt, which has a low ability to graphitize.

The disadvantage of this invention is the presence of cement, as a binder, since its application denotes the presence of additional silica and alumina (SiO _2, Al ₂ O _3), which adversely affect properties of the steel.

The closest solution in technical essence to the invention is the “Method of out-of-furnace steel processing in a ladle” (patent No. RU 2219249, C21C 7/00, C21C 7/06, 12/20/2003). The invention relates to ferrous metallurgy, and more particularly to out-of-furnace processing of steel in a ladle using complex deoxidizers.

, где Q₁ - расход комплексного раскислителя в процессе выпуска, кг/т; Q₂ - расход комплексного раскислителя после выпуска, кг/т; C₁ и С₂ - содержание углерода в расплаве при начале выпуска и необходимое содержание углерода в готовой стали, мас. %; Si₁ и Si₂ - содержание кремния при начале выпуска и необходимое содержание кремния в готовой стали, мас. %; K₁ и K₂ - эмпирические коэффициенты, равные 1,6-10,0 и 0,33-8,0 соответственно, кг/т. Затем расплав легируют алюминием в виде катанки с расходом в пределах 0,3=0,7 кг/т расплава и продувают аргоном в течение 1-15 мин с расходом 0,5-2,0 л/мин на тонну.The method of out-of-furnace steel processing in the ladle includes the release of the melt from the steelmaking unit into the ladle, feeding into the ladle, during the process of releasing the deoxidizing melt, alloying and slag-forming materials. As a deoxidant, silicon carbide with a fraction of 0.1-10 mm, containing 80-90 wt. % pure silicon carbide, 2-5 wt. % free carbon, the rest is impurities. The deoxidizer is fed during the production process with a flow rate of 1-5 kg / t of melt according to: Q ₁ = K ₁ (C ₂ -C ₁ ) / (Si ₂ -Si ₁ ). After release, an additional deoxidizer is additionally supplied in the range of 0.2-0.4 kg / t of melt and aluminum with a flow rate in the range of 0.1-1.5 kg / t of melt. The deoxidizer is served according to:

where Q ₁ - the consumption of a comprehensive deoxidizer in the manufacturing process, kg / t; Q ₂ - consumption of complex deoxidizer after release, kg / t; C ₁ and C ₂ - carbon content in the melt at the beginning of production and the required carbon content in the finished steel, wt. %; Si ₁ and Si ₂ - silicon content at the beginning of production and the necessary silicon content in the finished steel, wt. %; K ₁ and K ₂ are empirical coefficients equal to 1.6-10.0 and 0.33-8.0, respectively, kg / t. Then, the melt is alloyed with aluminum in the form of a wire rod with a flow rate in the range of 0.3 = 0.7 kg / t of melt and is purged with argon for 1-15 minutes with a flow rate of 0.5-2.0 l / min per ton.

The disadvantage of this invention is that the fraction of 0.1-10 mm does not fully reach the metal and partially (fraction less than 1 mm) is carried away by the gas-air heat flow coming from liquid steel. Fraction 0 - less than 1 mm is not in demand in the metallurgical industry, increases the cost of production and requires additional disposal (waste disposal).

The challenge facing the invention is to increase efficiency (by replacing ferrosilicon, saving carburizing, increasing the absorption coefficient of silicon and reducing material losses) and environmental friendliness of the production of iron and steel. As well as expanding the possibility of using unclaimed screening of silicon carbide by pressing the desired size of silicon carbide fractions into briquettes.

The problem is solved due to the fact that the complex deoxidizer of steel (KRS) is presented in the form of fractionated lumpy silicon carbide with a fraction of more than 1 mm and fully acts as a substitute for ferrosilicon (ZFS) and carburizer. A fraction of less than 1 mm is not used in metallurgy, and is removed by vibration screening. This processing allows you to clean the deoxidizer from a fraction of less than 1 mm, which does not reach the metal, and is carried away by the gas-air heat flow coming from the liquid melt. Also, by drying the substitute for ferrosilicon, a moisture content of less than 1% is achieved, which avoids saturation of the melt with gases.

The technological scheme of production and movement of materials at the iron and steel enterprises does not provide for the use of a fine fraction of less than 1 mm in size, since its use leads to spillage (irretrievable loss) of material, economic losses and environmental degradation in the workshop.

Screening of fractions and their briquetting into a lump complex deoxidizer of steel (KRS) allows it to be used as a substitute for ferrosilicon (ZFS) and a carburizer in metallurgy, which increases the efficiency of deoxidation and alloying of steel, reduces the cost of steel production since silicon carbide is cheaper than ferrosilicon , and surpasses ferrosilicon in technical characteristics, since it contains up to 30% of the total carbon, which significantly increases the absorption of silicon in the metal.

The essence of the described technical solution is that the material used is lump substitute ferrosilicon (ZFS) - fractionated silicon carbide (SiC) with a fraction size of more than 1 mm, which has passed vibration screening and heat drying, as well as its screened fractions less than 1 mm, briquetted onto beet molasses by vibropressing into cylinders with a diameter of up to 60 mm and a height of up to 70 mm, or briquetted on an inorganic binder using a roller briquette press into “tablets” with a diameter of up to 40 mm and a height of 30 mm with strength not less than 400 kg / cm ² and humidity not more than 1%. The final specified content of silicon carbide in the briquettes from 70 to 90%.

The production of a comprehensive steel deoxidizer (RRS), which acts as a substitute for ferrosilicon (ZFS) and a carburizer, based on lump silicon carbide is carried out as follows. The starting material is the battle and scrap of carborundum stones with SiC content from 80% to 95%, as well as black crystalline silicon carbide for metallurgical production with SiC content from 88% to 97%), packed in soft big-bag MKR containers, passes input control. After receiving the analysis results, using a crane beam with a lifting capacity of 3 tons, it is poured into the receiving hopper of the conveyor for loading the vibrating sieve N-SV-2042 for sieving.

The vibration sieve consists of 4 sieves with cells 5 × 5 mm, 3 × 3 mm and two lower sieves 2 × 2 mm, which guarantee high-quality vibration screening of the material and exclude particles less than 1 mm from entering the finished product. When the moisture content of the starting material is more than 1%, during the vibration screening, the material more than 1 mm is blown with hot air from the heat gun.

The sieving of the fraction through a sieve with 2 × 2 mm cells is caused by the subsequent possible grinding of the fraction during packing and transportation.

A fraction of more than 1 mm is issued from under the vibrating screen by roller conveyor No. 1. Screening fraction less than 1 mm is issued by roller conveyor No. 2.

During the screening, a finished fraction of more than 1 mm is accumulated in soft big-bag MKR containers to prevent accidental mixing with a drop-out of less than 1 mm. The fraction material of more than 1 mm and the screenings are weighed on a VK balance crane scale.

Screening of a fraction of less than 1 mm is briquetted on beet molasses by vibropressing into в 57 × 50 mm or ∅ 57 × 70 mm briquettes (cylinders) or on an inorganic binder using a roller briquette press into ∅ 40 mm briquettes and a height of 20-30 mm s strength not less than 400 kg / cm ² and humidity not more than 1% with a final specified content of silicon carbide SiC from 70% to 90%.

The technical result of the application of the proposed invention is to increase the efficiency of the use of lumpy silicon carbide, the possibility of using its screening (unsuitable for use in the steel industry) in the form of briquettes, as a complex deoxidizer of steel (RED), which is a complete substitute for ferrosilicon (ZFS) and carburizing agent. The use of real large-sized materials allows the combined deoxidation and alloying of steel with silicon and carbon, contributes to a higher degree of assimilation of the leading elements (carbon, silicon, manganese) in steel and cast iron, reduces the cost of production of steel and cast iron, and also improves the environmental situation in the metallurgical atmosphere workshops.

Thus, the problem posed to the invention is solved.

The complex deoxidizer of steel based on lump silicon carbide is illustrated by additional materials, which are reflected in the graphic part: sieving and drying scheme, photographs of fractions, briquettes and “tablets”.

Steel production was carried out in accordance with applicable regulations. The complex deoxidizer of steel KRS-65 of a fraction of 1-20 mm was seated during the release of metal from chipboard instead of BKK-92 of a fraction of 0-10 mm.

Upon receipt of KRS-65, incoming inspection was carried out for compliance with the requirements of TU 398900-018-82389246-2011.

Table 1 shows the chemical and fractional compositions of KRS-65 according to the technical specifications, certificate and input control.

From table 1 it can be seen that KRS-65 meets the requirements of technical conditions.

Table 2 shows the number of silicon-containing materials seated during the release from chipboard and during out-of-furnace steel processing at UKP in the production of steel grade St3sp using KRS 65 (at 27 heats) and BKK-92 fraction 0-10 mm (at 44 heats).

From table 2 it is seen that in the production of steel grade St3sp:

- when using BKK-92, the absorption coefficient of silicon at the release from particleboard was 44.9%;

- when using KRS-65, the absorption coefficient of silicon at the release from particleboard was 47.9% (+ 3.0%),

Table 3 shows the number of silicon-containing materials seated during the release from chipboard and during out-of-furnace steel processing at the UKP during the production of steel grade St3Gsp using BKK-92 fractions of 0-10 mm (for 48 heats) and KRS-65 (for 59 heats).

From table 3 it is seen that in the production of steel grade St3Gsp:

- when using BKK-92, the absorption coefficient of silicon at the release from particleboard was 51.1%;

- when using KRS-65, the absorption coefficient of silicon at the release from particleboard was 55.5% (+ 4.4%).

Table 4 shows the number of silicon-containing materials seated during the release from chipboard and during out-of-furnace steel processing at UKP in the production of St3ps steel using BKK-92 fractions of 0-10 mm (for 17 heats) and KRS-65 (for 19 heats).

From table 4 it is seen that in the production of steel grade St3ps:

- when using BKK-92, the absorption coefficient of silicon at the release from particleboard was 41.8%;

- when using KRS-65, the absorption coefficient of silicon at the release from particleboard was 44.8% (+ 3.0%).

A higher absorption coefficient of silicon when using KRS-65 in comparison with BKK-92 is associated with the absence of a fraction of less than 1 mm in it, which reduces losses due to the addition of material at the outlet of the smelter from chipboard.

Table 5 shows the calculation of the consumption of BKK-92 and KRS-65 for alloying steel grade St3sp, St3Gsp, St3ps with silicon by 0.10%, taking into account the obtained absorption coefficients at the release from particleboard.

Table 6 shows the calculation of the average replacement rate of BKK-92 experimental material KRS-65, taking into account the proportion of substitution.

From table 6 it is seen that the average replacement rate of BKK-92 with experimental material KRS-65 is 0.916, i.e. To replace 1 ton of BKK-92, 0.916 ton of KRS-65 is required.

Findings:

1. KRS-65 meets the requirements of technical conditions.

2.1. In the production of steel grade St3sp:

- when using BKK-92, the absorption coefficient of silicon at the release from particleboard was 44.9%;

- when using KRS-65, the absorption coefficient of silicon at the release from particleboard was 47.9% (+ 3.0%).

2.2. In the production of steel grade St3Gsp:

- when using BKK-92, the absorption coefficient of silicon at the release from particleboard was 51.1%;

- when using KRS-65, the absorption coefficient of silicon at the release from particleboard was 55.5% (+ 4.4%).

2.3. In the production of steel grade St3ps:

- when using BKK-92, the absorption coefficient of silicon at the release from particleboard was 41.8%;

- when using KRS-65, the absorption coefficient of silicon at the release from particleboard was 44.8% (+ 3.0%).

2.4. A higher absorption coefficient of silicon when using KRS-65 in comparison with BKK-92 is associated with the absence of a fraction of less than 1 mm in it, which reduces losses due to the addition of material at the outlet of the smelter from chipboard.

3. The average replacement rate of BKK-92 with experimental material KRS-65 is 0.916, i.e. To replace 1 ton of BKK-92, 0.916 ton of KRS-65 is required.

Claims (3)

1. Material for the deoxidation and alloying of iron-carbon alloys with silicon and carbon, characterized in that the material used is lump silicon carbide (SiC) with a fraction of more than 1 mm and a moisture content of less than 1% and its briquetted screening fraction of less than 1 mm with a final content in briquettes the main element of SiC 70-90%. 2. The material according to claim 1, characterized in that the screening of SiC fractions of less than 1 mm is briquetted using beet molasses by vibrocompression into cylinders with a diameter of up to 60 mm and a height of up to 70 mm. 3. The material according to claim 1, characterized in that the screening of SiC fractions of less than 1 mm is briquetted using an inorganic binder using a roller briquette press into tablets with a diameter of up to 40 mm and a height of up to 30 mm with a strength of at least 400 kg / cm ² .

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