Device for metal refining in the pony ladle

Abstract

 The invention relates to ferrous metallurgy, in particular to devices for steel refining by rare gas in a pony ladle. The device for metal refining in the pony ladle containing tuyere placed axially to a flow of effluent metal and done in such a way as to allow creation of rare gas bubbles flow is directed to guarantee maximum outlet of inclusions to refinery slag.
For the purpose of resisting whirl metal movement occurring above nonswirl nozzle the inner surface of the receiving cone of the device is configured in the form of rectangular prism converting to truncated cone and creation of rare gas bubbles flow is provided by a porous refractory insert placed in the body of tuyere in such a way that the form thereof in cross section duplicates the form of the inner surface of the receiving cone.

Description

[0001] This invention relates to ferrous metallurgy, in particular to devices for steel refining by rare gas in the pony ladle.

[0002] Known is the device for EBT (external bottom tapping) discharge metal from EAF [1], where the outlet pot of the EBT in the profile is rectangular oval shaped and has conidial form.

Known are the schemes and devices for steel refining by rare gas in the pony ladle [2, 3].

[0003] The period of single portion of metal in pony ladles is extremely limited and insufficient for effective removal of basic mass of inclusions. Fall in temperature results in steel self - deoxidation and formation of the sufficient quantity of exogenous nonmetallic inclusions. At the same time small pieces of lining are washed away by metal convection current. This leads to formation of exogenous nonmetallic inclusions. Besides, the whirl metal movement in the form of crater occurs during outflow of the metal stream from pony ladle above nonswirl nozzle and nonmetallic inclusions and small pieces of slag are swallowed in. The above known schemes and devices have complex construction and do not provide competence of outlet of nonmetallic inclusions and small parts of slag from metal.

[0004] The most similar to the claimed device is the device for metal refining in pony ladle [4] which contains ceramic tuyere placed in the pony ladle axially to a flow of metal flowing to the mold and done in such a way as to allow creation of bubbles flow of rare gas axially to mentioned flow of effluent metal. The mounting of the ceramic tuyere in the close proximity to the zone of accumulation of nonmetallic inclusions allows to increase the effectiveness of refining and the curtain of rare gas bubbles causes certain braking of radial speed in metal flow. However the above-mentioned device recognized as a prototype does not provide sufficient fall of radial speed in metal flow flowing through a pony ladle and consequently competence outlet of inclusions to refining slag is not achieved as the prototype does not disclose the impact of the geometric form of the inner surface of the tuyere on decrease in radial speed in the metal flow. Besides according to the prototype the porous insert included to the tuyere frame for making bubbles flow of rare gas is ring - shaped in sections. The indicated ring shape is not the best one from the point of view of increasing the quantity the bubbles of rare gas. Activity of the curtain from rare gas penetrating into metal can be enhanced by increasing a quantity of bubbles that will consequently result in further decrease in radial speed in metal flow which is flowing through the pony ladle.

[0005] The technical result achieved by this device is that maximum outlet of inclusions to the refining slag is provided.

[0006] The achievement of the technical result allows solving the assigned task by means of the proposed device for metal refining in the pony ladle containing the tuyere which is placed axially to the flow of effluent metal and made in such a way as to allow creation of a flow of rare gas bubble. According to the invention the inner surface of the receiving cone for metal flowing is configured in the form of rectangular prism (parallelepiped) converting to a truncated cone. The body of the tuyere is provided with the porous refractory insert covering the inner surface of the receiving cone in order to resist the whirl metal movement occurring above nonswirl nozzle. The geometrical form of the insert in cross section duplicates the form of the inner surface of the receiving cone for metal flowing.

[0007] According to the invention the body of the tuyere is made predominantly of gas proof concrete material; the external face of the body of the tuyere in cross cut along long axis has the form of truncated cone and besides the mentioned body of the tuyere is supplied with connector with holes (one or more) for rare gas admission.

[0008] The essence of the invention is exposed in the figures.

Fig. 1 discloses the device for metal refining in the pony ladle.

Fig. 2 discloses the scheme for setting the refining device in the pony ladle and the scheme of rare gas admission.

[0009] The drawings contain the following elements:

1 - the body of the tuyere for metal refining; 2 - porous refractory insert; 3 - the inner surface of the body of the tuyere serving as receiving cone; 4 - the pony ladle; 5 - an effluent flow of metal; 6 - the flow of rare gas bubbles; 7 - the outlets for rare gas admission; 8 - the nonswirl nozzle.

[0010] The device for metal refining from nonmetallic inclusions and gases contains tuyere, body 1 of which is made of gas proof refractory material and has the form of a truncated cone.
The porous refractory setting is placed into the body 2, which allows creating a flow of rare gas bubbles 6, predominantly argon, with diameter up to 3mm.

[0011] The inner surface 3 of the body of the tuyere serving as a receiving cone is configured as rectangular prism (parallelepiped), converting to truncated cone to let metal in. The rectangular prism form of the inner part of device allows to resist metal whirl movement over the nonswirl nozzle 8.
There are some holes 7 for rare gas admission in the inner part of the body 1 which is connected with porous refractory insert 2.
Fig.2 represents the variant of mounting the refining device where metal flows to the pony ladle and farther to the mold.
The mounting the device for metal refining in the pony ladle (as figure 2 represents), is realized directly close to outgoing metal flow 5 and pony ladle 4 to the mold (figure 2 does not represent), that means the body 1 of the device is mounted in the pony ladle 4 axially to the flow 5 of metal flowing from pony ladle to the mold.
The functioning of the device is fulfilled in the following way.
The metal flow 5 enters to the inner part of the body of the tuyere 3 acting as a receiving cone. By means of holes 7 connected with porous mass of refining insert 2 covering the inner surface 3 in the form of rectangular prism, the flow of inputted rare gas (for example argon) is changing into flow 6 of bubbles penetrating liquid metal. The rare gas converting in the pony ladle is fulfilled in the bubble flow in order to prevent exposure of the metal surface.
The refractory insert 2 covering the inner surface 3 has the same form in the cross-section as the inner surface 3 which is rectangular. During the converting process the inputted rare gas is heated at the expense of heat loss through the lining of pony ladle.
The principle of refining by rare gas is based on the flotation method that is adhesion of nonmetallic inclusions to rare gas bubbles and outflow of the inclusions to the slag.

[0012] The inner part of the device is in the form of rectangular prism (parallelepiped) allowing resisting metal whirl movements above the nonswirl nozzle and reducing considerably the kinetic energy of nonmetallic inclusions, excluding entering to the outgoing flow. That can guarantee maximum flowing out of nonmetallic inclusions by the bubbles of rare gas to refinery slag.

[0013] The form of refractory insert 2 is also in the form of rectangular prism and duplicates the form of the inner surface of the tuyere. Such characteristics allow increasing the quantity of outgoing rare gas bubbles by extending the area of porous mass insert emitting the flow relative to prototype and as the result to increase effectiveness of the flotation process.

[0014] The rare gas converting directly before crystallization allows not only to reduce the quantity of nonmetallic inclusions that are already in metal as well as to prevent ingress to the ingot of endogenous inclusions which are a result of steel self - deoxidation by fall in temperature in the pony ladle in the process of casting. Rare gas converting just prior to crystallization has an additional positive effect which is the decay of hydrogen content to extremely low values and partial removal of nitrogen according to Sivert's law

[0015] Argon bubbles contain neither nitrogen nor hydrogen and they are evacuated chambers. As hydrogen has a high diffusion rate and practically does not come into strong chemical link in contrast to nitrogen that determines high degree of hydrogen removal. Hydrogen moves away insignificantly because of low degree of diffusion and property to form strong chemical bonds with some metals.

[0016] Sources of information

1. BY 2736 U, IPC7 B22D 11/10, 27/20 published 30.06.2006

2. G.V. Efimov, Physico - Technological Institute of Metals and Ferro-alloys of The Ukraine National Academy of Science. The process of steel refining in a pony ladle. Steel, 2001, #4.

3. V. Y. Sakulin, V. P. Migal Public corporation "Borovichy refractory plant". Production and application of refractory devices for steel refining out of furnace. Electrometallurgy 2004 #3.

4. Application EA 200501284 A1, IPC7 B22D 11/116 published 27.04.2007

Claims

1. Device for metal refining in pony ladle containing the tuyere placed axially to flow of effluent metal and made in such a way as to allow creation of a flow of rare gas bubble, characterized in that in order to resist whirl metal movements occurring above nonswirl nozzle, the inner surface of the receiving cone for metal flowing is configured in the form of rectangular prism converting to truncated cone, creation of rare gas bubbles flow is provided by a porous refractory insert placed in the body of the tuyere in such a way that the form thereof in cross section duplicates the form of the inner surface of the receiving cone.

2. Device for metal refining according to claim 1 characterized in that the body of the tuyere is made of gas proof concrete.

3. Device for metal refining according to claims 1 or 2 characterized in that the external face of the body of the tuyere in cross cut along long axis has the form of truncated cone.

4. Device for metal refining according to any claims 1 - 3 characterized in that the body of the tuyere is supplied with holes for rare gas admission.

Drawing