US2197259A - Method of and apparatus for adding lead to steel - Google Patents

Description

April 16, 1940.

J. H. NEAD METHOD OF AND APPARATUS FOR ADDING LEAD TO STEEL med May 2, 1938 INVENTOR John Hunfer Nead.

' ATTORN Y5 Patented Apr. 16, 19

UNITED STAT 2,197,259 METHOD or AND APPARATUS 'roa ADDIN PATEN oFFic LEAD TO STEEL John Hunter Nead, Hammond, Ind, asslgnor to Inland Steel Company, Chicago, EL, a corporation oi Delaware Application May 2, 19st, genial No. coasts 4i Cid greatly improves themachinability of the steeL' particularly, when more than .10 per cent is retained in the steel. This is true whether or not the lead be introduced into the so-called free cutting steels or whether it be used in other types of steels. When introduced into the free cutting steels, it results in an improved machinability over and above the free cutting characteristics imparted to thesteel by' the sulfur and, in addition, does not impair the mechanical characteristics of the steel. When used, in adequate percentages, with steels of relatively low sulfur content as, for instance, in steels containing less than .05 per cent sulfur, it imparts improved machinability characteristics and in some instances gives free cutting characteristics which compare favorably with machinability characteristics ,of

some of the present commercial free cutting" 20 steels. Moreover, the improvement in machinability by the use of lead avoids sacrifice oi the mechanical properties of the steel such as occurs when the improved machinability is obtained by somewhat higher sulfur contents.

In the prior art, it has been suggested that lead be added to steel for the purpose of preventing "piping" and "blow holes and for various other purposes. In the main, however, it has generally been believed 'inthe art that lead 0 not be used in steel'to attain any useful results.

Such suggestions for the use of lead in steel as have appeared in prior patents appear to have been impracticable. In the main, they have involved the introduction of lead into the steel in the form of ingots of substantial size. Normally,

when such ingots are introduced into a bath of is not soluble in iron and therefore that it could der some conditions, introducing lead into the ladle used with the open-hearth has resulted in excessive fuming and inability to control the amount of lead actually dispersed throughout the molten bath. The lead separated out and settled to the bottom of the bath, even rug through the nozzle,-in spite oi the fact that the stopper was closed.

I have found, however, that these various difficulties may be overcome by introducing the lead into the mold. This is especially so it the lead is introduced into the mold in a cert way and under certain conditions. Preferably the lead to be introduced is in sub-divided form. it may be finely divided lead ranging from ill to'Si) mesh in size or it may be small shunks of lead.

On the other hand, it may be introduced in the form of lead compounds or alloys, oiwhich the following are examples:

Lead-tin-antimony alloy Galena (PbS) Ratio izlzl Pure lead Lead-tin alloy 60% Pb, Sn

I'ead-wopper-tin alloy 82% Pb, 66% Cu,

Litharge PbO Lead phosphate; Pba(P0s)a Lead tin alloy (1.5% Sn) Lead calcium a loy .6% Ca) Lead bismuth alloy (3% Bi) Lead arsenic alloy (1.1% As) Lead cadmium alloy .5% Cd {it 1.6%

Lead tellurium alloy .l% Te) Lead antimony alloy (1.7% Sb) Lead lithium alloy .l% Li) Lead zinc alloy -.3 Zn 8.: .9% Zn) Lead sodium alloy 3% Na) Lead magnesium alloy 3% Mg) Lead-manganese-iron alloy-. (20% Pb 46% Min (33% Fe) plus impurities PbS, Fes (64% Pb 13% Fe 17% 8 plus impurities) Pb-Fe-S alloy I have found that the introduction of the lead into the steel and the dispersion thereof is rendered much more effective if such introduction occurs during the pouring of the steel into the mold. Best results seem to be obtained by first filling the mold about one-third or one-half full of steel and then introducing the lead during the last two-thirds or one-half of the mold filling operation. So far, the best results which I have obtained have been obtained by utilizing substantially pure lead in sub-divided form and deliverlng it by means. of a trough directly against the downwardly flowing stream of steel at about the entrance to the mold. In this way, the lead is introduced as a stream of finely divided metal and mixed more. thoroughly and is dispersed throughout the steel in the mold. This lead may also be introduced as a spray of molten metal. Likewise, it is possible to put thelead on top of the charge in the mold. However, my experiments to dateshow that, even though finely divided, the lead, when introduced at the'top of the ingot or after completion of the pouring of the ingot, tends to collect into large masses and then sinks to the bottom of the mold without being effectively dispersed to any substantial extent throughout the body of the steel in the mold.

acters of reference designate corresponding parts and wherein:

Figure 1 is a diagrammatic illustratlonof a ladle shown in position for delivery to the mold together with a trough for delivering the lead and a means for removing the poisonous gases and other fumes by forced drafts.

Figure 2 is a side elevation of the elements shown in Figure 1.

Figure 3 is a somewhat enlarged perspective diagrammatically illustrating one mold with my apparatus for feeding the lead into the mold and removing the gases and fumes therefrom.

Figure 4 is a diagrammatic illustration of my lead delivering apparatus and gas removing apparatus, shown partly in section and illustrating its relation to the mold and the ladle. 1

Figure 5 is a detailed view of one of the connections between the forced draft apparatus and the removable hood structure which is designed for successive applications to a series of molds,

as indicated.

In the drawing, the ladle is shown at I. ladle is of customary form and is provided with the usual nozzle 2 and the customary stopper which is not shown. A series of molds is shown,

these molds being designated 3 and being mounted upon conveying cars 4 which move upon a track 5 along the edge of a platform 5.

Beneath. this platform 6 is provided a conduit 1 which may be connected to an exhaust fan (not. shown) or other form of means for creating a forced draft. This conduit I is provided at spaced intervals with upstanding ducts 8 each of which carries at its upper end a sand seal 9. These,-

upstanding ducts 8 are preferably provided at spaced intervals corresponding to the spaces between the central areas of the spaced molds of the mold series.

I preferably use one removable hood which is generally designated I0 and which is designed for successive applications to each upstanding duct 8 and the corresponding mold of the series. This hood I0 is provided on its upper and outer surface with a cutaway portion H which is of sufficient area to permit free flow of the stream This of steel therethrough into the mold and simultaneous introduction of the lead by means of a trough I2 as shown. The-hood is further provided with a converging extension member l3v which carries the downwardly extending duct l4 designed to be introduced into the sand seal 9 and into telescoping relation with an upstanding duct 8.

Though I have described one type of removable hood, it will be understood that various types of hoods may be used. As a matter of fact, it is within the scope of my invention to use any desired type of apparatus for removing the fumes and gases under forced draft. For example, I may use any means such as a mere vacuum or high suction slot hood which would not cover the top of the mold but would only provide a suction opening adjacent to the mold top. In fact, any type of hood or suction opening which would remove the fumes is within the scope of my invention. Likewise, it is within the scope of my invention to remove the fumes and gases by blowing air under pressure across the top of the mold or otherwise-to dispel such fumes and gases.

It will be understood that it is within the scope of my invention to introduce the lead either in the form of sub-divided metallic lead, lead alloys or compounds of lead or lead-bearing minerals.

In operation, the filling of each mold is preceded by placing the hood III on top of the mold with its downwardly extending duct H in cooperative relation to the sand seal 8 and upstanding duct 8, as illustrated in Figures 3 and 5.

Then, the ladle is moved into the position shown in the drawing and the stopper lifted so as to permit the steel to be delivered into the bottom of the mold in the usual manner until the mold is about one-third or one-half filled. Then, while the filling operation continues, the sub-divided lead is delivered to the trough I2 and into the mold, as indicated in Figure 4 wherein it will be seen that the lead is being sprayed into contact with the downwardly'pouring stream of molten steel. Generation of the fuming gases commences as soon as the lead strikes the molten steel. However, since the forced draft is already effectlve through the hood 10, these gases are drawn through the duct 8 and conduit 1 as they are generated. The result is that the work- .men are amply protected from these fuming gases and the delivery of lead to the steel proceeds without material discomfort to the workmen until the mold is filled, at which time, the delivery of the lead to the steel has been completed.

Having thus described my invention, what I claim is:

1. Apparatus for use in the introduction of lead into steel comprising a means for introducing lead into a container having molten steel therein and means for simultaneously removing the gases and fumes generated thereby by means of an. air draft over the open end of the container.

2. Apparatus for use in the introduction of lead into steel while being poured into an ingot mold comprising a hood-like. member which covers the top of the mold with the exception of an area below the nozzle of theladle where it is provided with a cutaway portion to permit the introduction of the steel from the ladle and the lead to be combined therewith, and means for creating an air draft in said hood across the top of the ingot mold to draw the lead fumes away to a point where they will not be harmful.

3. The method of producing steel containing lead in condition, which comprises pouring molten steel into a container therefor,

gradually introducing lead in finely divided conv ditlon into said container during said pouring, and simultaneously removing gases and fumes generated by the addition of the said lead by an air current abovethe top of the metal in said a container.

4. The method of producing steel containing lead in dispersed condition, which comprises pouring a stream of molten steel into a mold, delivering lead in finely divided condition against the said stream of molten steel and introducingit into the mold therewith, and simultaneously.

removing gases and iumesgenerated by the addition of the said lead by an air current above the top of the metal in said mold.

JOHN HUNTER CERTIFICATE OF CORRECTION. Patent No. 2,197,259. April 16, 191 0.

JOHN HUNTER NEAD.

It is hereby certified that error appears in the printed specification of the above ninnbered patent requiring correction as follows: Page 1, second column, lines 20, 21 and 22, in the table,for

"Lead-tin-entimony alloy Galena (PbS) Ratio 151:1

Pure lead read Lead-tin--z=.1'1t'.imon:, alloy Ratio 1:1:1 Galena (PbS) Pure lead and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed arfi sealed this 11th day of June, A. D. 191 0.

Henry Van Arsdale, 4 (Seal) Acting Commissioner of Patents.

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