RU2356685C2 - Method of receiving of semi-finished product for metalllurgical redivision - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: at receiving of semi-finished product preliminary treated mould by lime mortar of conveyor belt is filled in layers by alternation of iron-carbon alloy, temperature of which is higher liquidus temperature on 130 - 280°C, and oxide material of fraction 0.01 - 10 mm. Oxide material is fed from doped bins into mould central part and it is located in 1 - 3 layers. Thickness of layers of oxide material and iron-carbon alloy is no less than 20 mm. Filling of iron-carbon alloy into mould is implemented at conveyor rate 8-14 m/min. Correlation of length to width of each mould is (4 - 4.20): 1.

EFFECT: it is provided hardening of semi-finished product, increasing of yield.

3 dwg

Description

The invention relates to ferrous metallurgy, and specifically to a method for producing a semi-finished product for metallurgical processing.

A known method of producing a semi-finished product for metallurgical redistribution, including pre-filling the trough of the filling machine with a solid iron oxide filler, pouring it with liquid cast iron in two portions, characterized in that after pouring the first portion of cast iron onto the solid iron oxide filler, the crushed iron-carbon material is additionally loaded into the mold and then poured into the crushed iron-carbon material, and then filled a portion of cast iron [1].

Significant disadvantages of this method are:

- pre-filling the mold with a solid iron-carbon filler leads to low mechanical strength, the formation of significant spills during transportation and a decrease in technical and economic indicators when melting this material.

- additional costs for obtaining iron-carbon material of a certain fraction, for example, cast iron chips, and the need to install additional equipment for its separate introduction;

There is also a method of producing a billet of billets for metallurgical processing, including filling in molds of a casting machine of an oxide-containing material, casting of iron and molding of a billet, characterized in that during the pouring of molten iron and / or molding of the billet, materials are mixed in the mold [2].

Significant disadvantages of this method are:

- the need to install expensive additional equipment for introducing reagents that initiate mixing into the mold of the filling machine;

- the possibility of emissions of molten material due to the rapid course of reactions with an additional reagent;

- additional introduction of undesirable impurities into the composition of the billet for its subsequent conversion into steel.

There is also known a method of producing a billet stock, comprising loading oxide material into a casting mold and pouring an iron-containing melt, characterized in that molds with a ratio of H / D = 0.5-10.0, where H is the mold height, D are given as casting mold diameter equal to the square root of the cross-sectional area of the ingot located at half the height of the mold, while the melt is supplied at a flow rate of 1-20 tons min [3].

Significant disadvantages of this method are:

- the occurrence of additional volumes of work and equipment in connection with the need to impact on each billet billet a certain effort;

- the possibility of overflow trough molds filling machines and increased waste generation.

There is also known a method of obtaining a semi-finished product for metallurgical processing, selected as a prototype [4], which includes a dosed supply of solid filler in the molds of a casting conveyor machine and their subsequent filling with an iron-carbon melt fed along the trench gutter along the conveyor belt with at least two separate successive jets , characterized in that the melt is first supplied with a superheat temperature of 130-250 ° C in an amount of 1.2-2.1 times in excess of the total mass to be filled spruce, and subsequent pouring is carried out after crystallization of the melt, which occupies porosity of the filler and constitutes 35-60% of the first filled portion, while the temperature of the overheating of the melt in the second and / or subsequent pouring is reduced by 15-50% compared to the temperature of overheating during the first pouring and the melt is fed at an angle of 30-60 ° along or opposite the direction of motion of the molds, distributing the jet into separate streams according to the number of filled sections of the mold, and the width of the jet is maintained within 0.6-1.0 to the width of the mold.

Significant disadvantages of this method are:

- low mechanical strength of the material due to the release of oxide materials on the surface of the semi-finished product, leading to the destruction of the latter during transportation and overloads with the subsequent formation of significant spills of oxide material, and, as a result, a decrease in the yield of a standard semi-finished product;

- reduction of technical and economic indicators of smelting, and in some cases the creation of emergencies during steelmaking due to the low mechanical strength of the semi-finished product and the formation of significant spills of oxide material;

- low technological productivity in the manufacture of semi-finished products due to a decrease in the superheat temperature by 15-50% compared with subsequent pouring and the inability to completely mix when filler is fed before pouring the iron-carbon melt;

- decrease in the melting rate of the semi-finished product when used in furnaces due to the non-optimal distribution of solid material (oxide filler) in the semi-finished product.

The desired technical results of the invention are: increasing the strength of the semi-finished product, increasing the yield upon receipt, increasing the technical and economic indicators of smelting and improving the quality of the smelted steel.

To this end, a method for producing a semi-finished product for a metallurgical redistribution is proposed, comprising dosing a solid filler in the form of oxide material into the molds of a casting conveyor machine and pouring it with an iron-carbon alloy fed into the molds along the trench ditch along the conveyor belt with at least two separate consecutive jets in which the mold pretreated with a lime mortar is filled layer by layer by alternating an iron-carbon alloy, the temperature of which higher than liquidus temperature by 130-280 ° С and fed from additive hoppers to the central part of the mold, the oxide material of the fraction is 0.01-10 mm, which is placed in 1-3 layers, and the thickness of the layers of the oxide material and the iron-carbon alloy is set to at least 20 mm and pouring the iron-carbon alloy into the molds is carried out at a conveyor speed of 8-14 m / min, while the ratio of length to width of each mold is (4-4.20): 1.

The claimed limits are selected experimentally.

The speed of the conveyor of the filling machine is selected based on the fact that when casting at a speed of less than 8 m / min, molds overfill and related emergencies occur, and when the speed of the conveyor of the filling machine is more than 14 m / min, incomplete filling of the mold, a decrease in the strength characteristics of prefabricated and reduced productivity of the filling machine.

The ratio of length to width, equal to (4-4.2): 1, is taken on the basis of ensuring maximum loading of containers for transportation, as well as ensuring the highest bulk density in steel furnaces.

The lime mortar treatment of the tundish of the filling machine prevents the semi-finished product from sticking to the trough of the filling machine and the occurrence of emergency situations.

The fraction of the added solid filler is selected based on the fact that with a fraction of less than 0.01 mm, additional grinding costs are required, and with a fraction of more than 10 mm, the surface of interaction of the solid filler with the carbon of the iron-carbon alloy is reduced, resulting in an increase in the melting time.

When the thickness of the layer of iron-carbon alloy or solid filler is less than 20 mm, the required strength of the semi-finished product is not provided.

When the temperature of the iron-carbon alloy is lower than the liquidus temperature of 130 ° C, there is a need to increase the speed of the conveyor belt for a faster spill, which in turn leads to an uneven distribution of solid filler in the body of the semi-finished product, and with an increase in liquidus temperature of more than 280 ° C, additional costs arise for overheating of the iron-carbon alloy and the likelihood of welding of the semi-finished product to the tons of filling machines.

The number of layers of solid filler in the semi-finished product more than three reduces the strength of the semi-finished product and leads to its breaking during transportation.

The inventive method for producing a semi-finished product for metallurgical processing was obtained by pouring solid fillers in the form of an oxide material with an iron-carbon alloy, the superheat of which was 193 ° C higher than the liquidus temperature. In the molds of the filling machine (Figs. 1, 2, 3), with a length of 536 mm and a width of 130 mm, pre-treated with lime mortar, at a conveyor speed of 8-14 m / min along the conveyor trench along the conveyor belt, an iron-carbon alloy was poured. Further along the belt, solid filler was fed from the filler bunkers with a layer thickness of at least 20 mm, which was then poured with an iron-carbon alloy from the next casting sock. When casting a semi-finished product with one layer of solid filler, one filler hopper and two casting socks were used. When casting a semi-finished product with two (further three) layers of solid filler along the conveyor belt of the filling machine, a second (further third) filler hopper, as well as a third (further fourth) casting sock, were installed.

Obtaining a semi-finished product for the metallurgical redistribution, manufactured by the present method, excluded its cracking during overloading and transportation, while spills of solid filler, which is part of the semi-finished product, was not observed. The yield of the product during casting on casting machines was 99.6%, taking into account the loss of metal in the casting ladle.

The semi-finished product was used for steelmaking in 100-ton electric arc furnaces with a transformer with a capacity of 95 MVA. The melts were blended both in a mixture with scrap metal, and at 100% loading of the furnace by the claimed semi-finished product. In the production of steel intended for railway rails of the NE76F and E76F grades, the content of chromium and nickel was reduced by 0.02%, copper to 0.03%, the contamination of steel with non-metallic inclusions was reduced (the average length of the line of oxides does not exceed 0.5 mm). The cost of smelted steel was reduced by 0.9-8.8 rubles / kg of steel.

Information sources

1. RF patent No. 2146181 B22D 3/00, C21C 5/52.

2. RF patent No. 2111079 B22D 3/00.

3. RF patent No. 2086342 B22D 5/00, 3/00.

4. RF patent No. 2127651 B22D 3/00, C22B 1/24.

Claims (1)

A method of obtaining a semi-finished product for metallurgical processing, comprising a metered supply of solid filler in the form of oxide material into the molds of a conveyor machine and pouring it with an iron-carbon alloy fed into the molds through the trench ditch along the conveyor belt with at least two separate successive streams, characterized in that the mold pretreated with a lime mortar is filled layer by layer by alternating an iron-carbon alloy, the temperature of which is higher than liquidus liquid at 130-280 ° C, and from the filler bunkers in the central part of the trough of the oxide material of the fraction of 0.01-10 mm, which is arranged in 1-3 layers, the thickness of the layers of the oxide material and the iron-carbon alloy being set to at least 20 mm, pouring the iron-carbon alloy into the molds is carried out at a conveyor speed of 8-14 m / min, while the ratio of length to width of each mold is (4-4.20): 1.

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