SU1235922A1 - Method of melting steel and alloys - Google Patents

Description

The invention relates to ferrous metallurgy, namely, to the production of steel and alloys in electric arc furnaces on a charge comprising metallized raw materials.

The purpose of the invention is to reduce energy consumption, save fuel consumption and improve the quality of steel.

The input of the metallized raw material causes the formation of a buffer layer of fir at the interface of the metal with the slag, the lower part of which is partially immersed in the thickness of the modular melt, and the upper part is in contact with the liquid putty. This arrangement of the layer is due to the fact that the density of the metallized sf is greater than the density of the slag, but significantly less than the density of the liquid metal. Due to this, the metallized raw material supplied to the bath surface, after passing a slag layer, is located at the interface of the metallized raw material - pshak, as a result of which the contact time of the metallized raw material with the slag increases many times over. An increase in the residence time of the pellets in Yulak allows an increase in the degree of heating and the temperature of the metallized sf before it enters the metal bath.

In addition, the oxidation of carbon contained in the metallized feedstock with iron oxides in this case, due to heating to the slag temperature, begins in the slag. The liberated carbon monoxide bubbles cause an additional increase in the duration of exposure to the slag bath. Ultimately, excess oxygen, which is present in the metallized bath, is removed from it already in the slag, thereby reducing the oxygen supply to the metal bath.

Slag mixing by gas puffs intensifies the heat exchange in the system of metallized SF — slag accelerates the penetration of the supplied charge materials and improves the heat utilization of the slag bath.

The number of one-time squatted metallized syf 5-25% of the total mass for smelting is selected according to experimental data. With a quantity of less than 5%, the duration of its contact with the slag is small and the raw material does not have time to reach high temperatures due to the slag. If that

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As a metallized raw material of more than 25%, the thickness of the charge mixture is large, which leads to excessive 3 / magnification of the duration of their stay in the layer, heating to high temperatures and, as a result, welding to the monolith, as well as excessive cooling of the slag and the appearance of conglomerates of metallized raw materials and scrap metal.

Example 1, In a 3-ton arc furnace with an acid lining, steel 20XH8L of the following chemical composition is smelted,%: C 0.25; Cr 0.3-0.6; Mp 0.15-0.45; Ni 7-8; Si O, 15; S; 0.06; P 0.06,

Melting is carried out as follows.

800 kg of waste from steel 20KhNZL and 20KhN8L and 50 kg of nickel are poured on the furnace hearth. After the filling has been melted and the receiving bath is formed into the furnace, evenly over the bath surface, 3600 kg of metalized kidneys are squatted. which is 15% of the total consumption of pellets for smelting. As a result, a layer of metallized raw material with a thickness of 0.12 m is formed on the surface of the bath. The remaining portion of pellets is fed continuously to the bath through the working window. After the end of melting, coking and ferrosilicon are deposited on the slag in an amount of 2 and 3 kg / ton of metal, respectively. After this, the sour donkey completely downloads and shifts a new one so as an additive of lime, fireclay and silica. Further operations — alloying and deoxidation of the metal — are carried out according to the current technological design.

The proposed technology provides an increase in the temperature of metallized raw materials to 200-250 ° C and a reduction in electric power consumption from 880 to 810 kWh / t due to better utilization of slag heat for heating pellets before entering them in a metal bath, as well as reducing oxidation. As a consequence, the reduction in the consumption of aluminum from 1 to 0.4 kg / t of steel compared to the existing technology.

Example 2 Melting was carried out in a 3-ton electric arc furnace, with 55 actual charges of 3.5 tons. Melting steel grade X32116L of the following chemical composition,%: C 2; Cr 30-36; Ni 5-7; Si 0.15-0.35; Mn 0.2-0.4; P and 05

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Melting is carried out as follows.

800 kg of ferrochrome and 200 kg of nickel are loaded on the furnace hearth. After the initial charge has been melted and the liquid receiving bath is formed, evenly over the entire surface of the bath, tAO kg is introduced into the furnace with oats, which is 5% of the total amount of pellets for smelting (2800 kg). The remainder of the bulk was fed continuously at a rate equal to the rate of penetration. Melting is further carried out according to a known technology.

According to this heat, electricity consumption is reduced to 14 KWh / t steel, and aluminum - by 0.2 kg / t steel. The relatively low reduction in power consumption and deoxidizing as compared with example 1 is due to the short duration of the intermediate layer of pellets at the boundary between the sack and the metal due to its small thickness. Therefore, in the next melt, the consumption of oceans for the formation of a layer is increased.

Example 3. Melting is carried out in the same furnace, melting the same grade.

Ohr I. Derbak 3062/24

Compiled by M. Menshikov Tehred L. Oleinik

Co Pod

Circulation 552 VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, st. Project, 4

359224

become. Smelting melting remained the same. After the initial filling has been melted and the receiving bath has been formed, 680 kg of pellets are introduced uniformly over the entire surface of the bath 5 onto the surface of the bath 5, which is about 25% of their total melting weight (2800 kg). With this, the power consumption is reduced to 780 kWh / t.

10 while reducing the consumption of aluminum to 0.5 kg / t of steel. A further increase in the consumption of oats (over 25%) is impractical, since the resulting conglomerates of metalized pellets and slag on the walls of the furnace are poorly melted, which negates the positive effect of the formation of an intermediate layer of oxygate.

The amount of nitrogen in the metal is also reduced by a factor of 1.5 due to the more intense boiling of the slag bath.

The economic efficiency of the method is due to the reduction in the amount of aluminum from 1 to 0.4 kg / t, and the specific energy consumption by 70 KW. h

Proofreader L. Pilipenko Subscription

Claims (1)

METHOD FOR MELTING STEEL AND ALLOYS, including filling scrap and parts of metallized raw materials, smelting the initial filling, introducing the remaining part of metallized raw materials and smelting them, refining, deoxidation and alloying of liquid metal, characterized in that, in order to reduce energy consumption, save deoxidizers and improving the quality of steel, after the initial filling is melted and the receiving bath is formed, metallized raw materials are introduced into the furnace uniformly over the entire bath surface in an amount of 5-25% of its total mass per square meter. so that a buffer layer is formed at the interface between the metal and the slag, after which the remainder of the metallized raw material is fed continuously at a rate equal to the penetration rate, and along the course of melting, the thickness of the buffer layer of the metallized raw material is kept constant. SU „„ 1235922 1 1235922 2