US3503597A - Metal treating device - Google Patents

Description

March 31, 1970 H. H. KEssLER ET AL 3,503,597

METAL TREATING DEVICE Filed Feb. 20, 1967 Fig? Al 24 o ll JNVENTOR; HARRY H. KEssLER WILLIAM H. MUORE w BY uw, m.

United States Patent() 3,503,597 METAL TREATING DEVICE Harry H. Kessler, 7 Dromara Road, Clayton, Mo. 63105, and William H. Moore, Meadow Lane, Purchase, N.Y.

Filed Feb. 20, 1967, Ser. No. 617,364 Int. Cl. C21c 7/00; B05b 1/14 U.S. Cl. 266-34 1 Claim ABSTRACT OF THE DISCLOSURE A readily movable and portable gas insufating device for stirring molten metal Which includes an elongated member or tube with a gas opening therethrough into which gas in introduced through a gas connection at one end of the tube and a readily detachable holder secured to the other end of the tube and holding a gas permeable ceramic refractory plug which is in communication with the gas opening at one of the ends and which has its other end exposed for contact with the molten metal.

The present invention relates to a device for the insufliation of gas into a mass of molten metal, in order to subject the metal to various treatments and, particularly relates to a portable device which can be used on ladles, furnaces, and any receptacle for molten metal.

The process of stirring metal by means of gas is Well known to those skilled in the art. Over the years many devices and forms of equipment to accomplish this purpose have been devised; for example, the stirring by gas was first accomplished using green wooden poles. More modern devices have used lances or hollow refractory shapes, which are plunged into the metal below the surface thereof and from which gas is bubbled into the molten metal. This produces agitation, which is suitable for stirring.

Still more recent devices use a porous refractory plug which is placed in the bottom or side of the ladle or vessel, below the metal surface and through which gas, under pressure, is forced into the metal. This device is a considerable improvement, in that it provides small gas bubbles, greatly increasing the surface area of gas to metal and providing a very pronounced ow and movement in the metal, capable of drawing alloys and low specific materials deep down into the body of the melt.

Contrasted to this, the commonly used lance method presents the problem of relatively large bubbles of gas, which, besides requiring high gas volumes which cool the metal, also do not give as well defined a stirring action to the metal. The lance does have the advantage of being portable, so that it can be moved readily to any vessel of metal which requires stirring.

The porous plug arrangement has the disadvantage of requiring special assemblies on the ladle or vessel itself. This increases the cost and decreases the flexibility of such an arrangement. As the porous plug is normally placed in the bottom of a ladle or ves'sel, it can become covered with slag, when the vessel is emptied and this can cause blockage, so that it is no longer possible to pass gas through the plug.

An object of this invention is to obviate some of the disadvantages of the gas stirring methods now used by those skilled in the art. A further object is to provide a lance, fitted with a removable porous plug, thereby retaining the advantages of the porous plug, along with the advantages of the lance.

A further object is to provide an adjustable means of stirring at any particular portion of a bath of molten metal, thereby reducing the cost and time necessary for stirring.

3,503,597 Patented Mar. 3l, 1970 ICC Other objects of the invention may be readily apparent from the specification and the drawing FIGURE 1, in which the present invention is illustrated.

FIGURE 2 is a view taken generally along the line 2 2 of FIGURE 1.

In its preferred form, the invention comprises a lance 1() made of carbon or other refractory material or a metal pipe which has been suitably covered with a refractory, to withstand the action of molten metal.

One end of the lance 10 is provided with threads 11 and a refractory plug holder 12 is provided with corresponding threads to secure the two together as shown. This holder 12 may be readily removed, so that various sized holders can be applied, so as to maintain the correct surface area to ladle size relationship or, alternatively, plugs of higher or lower gas permeability may be fitted so as to promote effective control of the pressures necessary to pass the volume of gas required for efficient stirring of the metal bath. The holder 12 is provided with a cavity to receive a porous refractory plug 14 which is preferably tapered in configuration. The plug 14 should be permeable to gases and impervious to molten metal. The plug 14 is non-reactive with the metal and the pores therethrough are generally equally spaced so as to provide a series of discrete passages from which separate bubbles emerge. A gas connection 15 is provided at an end of the lance 10 opposite threads 11 and gas is communicated to plug 14 from a source (not shown) through an opening 16.

The lance of this invention permits the passage of extremely minute bubbles of gas through the metal in any position in the metal bath that is desired; thus, the gas flow or stirring may be confined to a portion of a bath, whereas in the conventional porous plug method, where the plug is fitted as an integral part of the ladle or vessel containing the molten bath, the stirring action occurs over the whole bath, or at least over a fixed portion of the bath.

By immersing the lance of this invention to different heights in the bath of metal, it is possible to accomplish a surface stirring effect or an overall stirring effect, as the case may be. Where the bath is extremely high in surface area in relation to metal depth, as would be the case in an air furnace or even an electric arc furnace, or a cylindrical type vessel, it is possible, with the lance, to accomplish effective stirring at successively different areas in the bath, which is practically an impossible procedure when such a vessel is lifted with a fixed porous plug contained in the refractory lining. By such selective mixing action, the overall gas treating time can be considerably reduced, thereby decreasing the metal temperature loss, which can occur when gas is injected into molten metal.

The improved lance of this invention has been used for many purposes; for example, when soluble alloys are added to molten metal, a surface stirring action is all that is required. This would refer to additions of ferrosilicon, nickel, copper, and the like to cast iron or steel. For this purpose, because the lance need not be injected to a great depth, lower gas pressures and volumes may conveniently be used.

For more insoluble additions, such as carbon to cast iron, the lance would normally be plunged to the bottom of the molten bath, so as to effectively incorporate the alloy completely throughout the mass of metal. For desulphurizing, also, the lance would be plunged to the bottom of the bath. Further than this, it would be moved in a horizontal direction, so as to promote stirring in all areas of the metal bath.

We lprefer to use a porous refractory for plug 14 made of materials such as; Alundum, corundum, magnesite,

silica, or zirconite, which is bonded under pressure and where 'the' aggregate is selected so as to provide a permeability suitable for the passage of the gas. A typical permeability would range `from 20 to 600.

.'In a conventional porous plug assembly, where the plug is fitted directly in the refractory of the ladle or vessel, it is necessary to use one or more plugs or to alter the surface area of the plug so as-to effectively stir all areas of the metal bath. The gas How and volume must also be adjusted accordingly. In the lance of this invention, a xed sized plug may be used,`as this plug may be moved around at will to all areas of the bath. This allows the use of a fixed gas flow. We prefer to use a plug approximately 11/2 to 2 in surface area, so as to avoid an excessively vheavy lance. This plug 14 is normally from 4" to 6" long and is conical in shape, so that it is conveniently held in the holder 12 which is a carbon refractory casing.v

` For simple stirring we prefer to use inert gases, such as nitrogen. For special purposes, we may use oxygen, air, chlorine, natural gas, propane, or any gas designed to have a definite metallurgical feffect. As an example of the process of this invention, we tapped 2,000 pounds of cast iron into a ladle where the depth of metal was approximately 24". We added 11/2 of calcium carbide to the surface of this metal and inserted the lance of the invention into the ladle, so that the plug was approximately 2 above the bottom of the ladle. We blew nitrogen gas at a pressure of 25 p.s,i..and at a i'low rate of 4 c.f.m. for a period of 11/2 minutes. During the blowing we-moved the lance across the surface of the ladle, so that the gas entered the vmetal at various points near the bottom of the ladle. We then removed the lance. A test sample taken from the metal before applying the lance and the calcium carbide, indicated a sulphur content of .105 After using -the' lance the sulphur content was found to be .014%. In similar tests on cylindrical type ladles we have found that we can very easily reduce the sulphur content of .a bath of cast iron to a value of less than .02% in a time of less than 2 minutes of blowing.

.Continued use of the lance results in some erosion of the refractory porous plug and we find that it is relatively easy to remove the plu'g holder and the plug from the lance, even While it is hot, and replace it with a new one. This can be done in a matter of one or two minutes.

, In certain instances 'we have found it advisable; for example; in receiving or mixing ladles, to put the lance in a relatively fixed position, so that it can be lowered into the metal at the most convenient point for effective mixing action. We do this by any of the means known -by those skilled in the art, such as; using a hydraulic cylinder to raise and lower the lance.

Another advantage of our preferred method is that we do not alter the balance of the weight distribution of the ladles, because the lance is not a fixed part of the ladle. This means that the pouring action of therladle is not altered in any way, because the lance is removed for pouring and it also means that legs or supports on the bottom of-y the ladle are not necessary, because the porous plug is not a part of the ladle, itself, as would be the case with a conventional porous plug, which is tted into the bottom of a ladle. Naturally, this makes for considerable economy where a large number of ladles, furnaces, or vessels are involved and are required to be fitted with a stirring device.

The lance of this invention is perfectly exible and can be moved from one ladle to another or from one furnace to another and from one portion of a metal bath to another with great facility.

It will be observed that the threads 11 are of such size as to permit removal of the plug 14 when member 10 and holder 12 are detached. This is a matter of convenience and it will be understood that the plug L4 may be rammed into position in the holder.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has ibeen made only by way of example and that numerous changes in the details of yconstruction and the combination and arrangement ofpparts may be resorted to Without departing from the spirit and scope of the invention as hereinafterk claimed.

What is claimed is:

1. A portable device for insufating a gas into a mass of molten metal including in combination an elongated annular member comprised of refractory material and having rst and second end portions and having an opening extending generally axially therethrough from said rst to said second end portion, means at said rst end portion of said member for connecting the same to a gas supply conduit to supply gas under pressure to said opening, a refractory holder, threaded means for removably attaching said holder to said second end portion of said References Cited UNITED STATES PATENTS 1,404,700 1/1922 Hardie 239-5533 2,515,600 7/1950 Hayes 239 553.3 3,053,525 9/1962 Leroy at a1. 3,208,117 9/1965 Gaadecke at a1. 1644456 FOREIGN PATENTS 772,842 4/1957 Great Britain.

I SPENCER OVERHOLSER, Primary Examiner U.S. Cl. X.R. Z39-590.3

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