RU173109U1 - DEVICE FOR METAL PURGE BY GASES IN A DUCK - Google Patents

Abstract

The invention relates to the processing of liquid metal by gases in a bucket. A device for purging metal by gases in a bucket comprises a nesting unit of a purge lance with a protruding part above the surface of the bottom of the bucket and a gas supply pipe. The protruding part of the nesting block has a conical shape, while the angle between the surface of the protruding part and the surface of the bottom of the bucket is 105-175 °. This ensures an increase in the service life of the device.

Description

The utility model relates to metallurgy and can be used in the processing of metal by gases in a ladle.

A device is known for purging metal with gases in a bucket (RU No. 2238984, C21c 7/072, 5/48 of 11/20/2002), comprising a socket unit, a purge lance, and a gas supply pipe.

The upper surface of this device is in the same plane with the surface of the bottom of the bucket. Due to the fact that the device for purging metal with gases in the bucket due to the action of gas operates in the most severe conditions, it fails earlier than the refractory lining of the bottom of the bucket. For this reason, the bucket must be decommissioned for additional repairs to replace the metal purge device much earlier than the bucket is decommissioned to replace its refractory lining. For this, the refractory lining must be cooled, which reduces its service life.

In order to increase the service life of the device for purging metal gases in the bucket (patent RU No. 2356691, B22D 41/58 of 09/09/2007), the length was increased due to the protruding part with protruding right angles, which is located in the liquid metal above the plane of the bottom of the bucket. Due to the low thermal conductivity of the refractory materials from which the devices for blowing metal with gases in the ladle are made, large thermal stresses arise between the very heated surface and their less heated inner part. In the said patent, in the protruding corners of the protruding part, the thermal stresses from the horizontal and vertical planes add up, and due to the high fragility of the refractories, cracks often form, which leads to the destruction of the nest block.

The closest in technical essence and the achieved technical result is a device for blowing metal gases in the bucket, containing a socket block, a blowing lance and a gas supply tube, in which the protruding corners of the protruding part due to the refractory packing mass is much larger than the right angle (RU No. 2180279, B22D 41 / 58 dated 10.03.2002). Due to this, the concentration of thermal stresses in these corners is less and, as a consequence, the probability of the formation of thermal cracks is reduced. The specified device is adopted as a prototype.

The disadvantage of this device is the occurrence of thermal cracks in the protruding refractory packing mass, because the refractory mass has a strength less than the refractory material of the block, which leads to premature failure of the device for blowing metal with gases and unscheduled decommissioning of the bucket.

The specified technical problem is achieved by the fact that the proposed device for purging metal gases in the bucket with a protruding part above the surface of the bottom of the bucket, containing a socket unit, a purge lance and a gas supply tube, characterized in that the surface of the protruding part has a rounded or conical shape, while the angle between the surface of the protruding part and the surface of the bottom of the bucket is 105-175 °.

During operation of the device for purging metal with gases in the bucket, a large difference occurs in the temperature of its outer layers in contact with the liquid metal and the inner layers. This leads to thermal stresses at the boundary between these layers. In this case, the thermal stress fields have the surface shape of the protruding part. In the proposed technical solution, the surface has a rounded or conical shape and does not have protruding angles; therefore, thermal fields do not overlap from different planes, there are no extremes of thermal stresses, and thermal stresses are close to the entire boundary between layers with different temperatures. They are less than the tensile strength of the refractory material from which the device for blowing metal with gases in the bucket is made, and therefore thermal cracking does not occur. The duration of operation of such devices is 15-20% longer than the design of the prototype. The figure shows a longitudinal section of the proposed device, which consists of a blowing lance 2, a socket unit 3 and a gas supply pipe 4. The protruding part 5 is located above the surface of the bottom of the bucket 1. Conditionally, both proposed surfaces are plotted simultaneously: 6 - rounded surface shape; 7 - conical shape of the surface. The rounded surface can be formed along the radius of the circle, along the radius of the parabola or in another way in which protruding corners are not formed. The conical surface also has no corners. Due to the presence of the connecting surface 8 between the block and the purge lance, as well as due to the large angle formed by surfaces 9 and 7, thermal stresses in this corner do not add up.

The service life of the device depends on the height of the protruding part, which, when the diameters of the block 10 and the purge lance 11 are fixed by the technological process of blowing metal with gas, can be expressed in terms of the angle of inclination of its surface to the surface of the bottom of the bucket. The angle of inclination of the conical surface is determined by the angle of inclination of its generatrix α (Fig.). The angle of inclination of the rounded surface is determined by the angle of inclination of its tangent at the junction with the bottom of the bucket β (Fig.). The angle of inclination 175 ° determines the minimum height of the protruding part 5 (Fig.), At which a significant increase in the service life of the device is already beginning to appear. With a decrease in the angle of inclination, the height of the protruding part increases, and the service life of the device also increases. However, this increases the depth of heating of the protruding part, and accordingly, thermal stresses increase, which can lead to the formation of cracks. The limiting angle at which this phenomenon does not yet occur is 105 °.

The proposed device for purging metal gases in the bucket is used to purge argon in the bucket of liquid metal smelted in electric arc furnaces with a capacity of 150 tons. It is made of aluminous low cement concrete. The dimensions of the nest block: diameter 360 mm, height 480 mm, height of the protruding part 30 mm, radius of rounding of its surface 90 mm, angle of inclination of the tangent 155 °. During operation, chips of the protruding part are absent.

Claims (1)

A device for purging metal with gases in a bucket, comprising a nesting unit of the purge lance with a protruding part above the surface of the bottom of the bucket and a gas supply pipe, characterized in that the protruding part of the nesting unit has a conical shape, while the angle between the surface of the protruding part and the surface of the bottom of the bucket is 105 175 °.

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