US1318164A - John mcconnell - Google Patents

Description

J. McCONNELL.

PROCESS OF MANUFACTURING ELECTRIC STEEL. APPLICATION FILED MAR. 3'1. 1919.

15318164. Patented 0ct. 7,1919.

steel.

Joan MccoNnELL, or CHICAGO, ILLINOIS.

PROCESS OF MANUFACTURING ELECTRIC STE-EL.

Specification of Letters Patent.

' Patented Oct. 7, 1919.

Continuation of applicationserial No. 210,803, filed January 8, 1918. This application filed March 31, 1919.

Serial No.

To all whom it may concern:

Be it known that I, JOHN MoCoNN LL, a citizen of the United States, and a residentof Chicago, county of Cook, and State of Illinois, have invented new and useful Improvements in Processes of Manufacturing Electric Steel, of which the following is a specification, the principle of the invention bein herein explained and the best mode in whici I have contemplated applying that principle, so as to distinguish it from other inventions.

This application is a continuation of my application for U. S. Letters Patent upon processes of manufacturing electric steel, Serial No. 210,803, filed Jan. 8, 1918.-

My invention relates to processes of manufacturing electric steel. Particularly does it relate to the duplex processes of manufacturing open-hearth electric-treatment steel and Bessemer-converter electric-treatment That is 'to say, my process is an improvement in and to the open-hearth and Bessemer processes for the purpose, economically and in large tonnages,'of superrefining the molten products that said open-hearth and Bessemer processes yield and for making special steels therefrom.

The objects of my invention are threefold: to obtain a large tonnage at a minimum cost, to obtain a more uniform product than any of which I am at present aware, and to require the use of less additions than heretofore by saving losses therein.

My invention comprehends the use of a suitably large receptacle, preferably the usual acid-lined ladle, for receiving the product of an open-hearth furnace, Bessemer-converter or other primary furnace, and refining such product by means of an electric current in said receptacle, the alloys having been added gradually to said product while being poured or tapped from the primary furnace to the receptacle, the current then being applied to the mixture in the receptacle for a comparatively short period; for instance, approximately fifteen minutes, when treating a high-grade open-hearth product.

I am aware that processes have been disfifty (50) tons or more, for instance,imay

be secured. at one operation the use .of

present standard equipment, and in order that heat may not be wasted in transferring the product to, and emptying the same into, a standard electric furnace or other refining receptacle, which is usually located a comparatively long distance from the primary furnace,-I prefer to subject the mixture (if steel and additions to electric treatment in the ladle or other receptacle which receives the product from the primary furnace, but th s is not necessary for obtaining the very {umform product, with the use of less addiparticularly'am I aware tions, which I secure by adding the alloys to the product as the latter is discharged from the primary furnace. Furthermore, a

fixed permanent position for electrification, including necessary electrodes, means for operating the latter, etc.,- may be established adj acently the primary furnace and the ladle may be transferred thereto for the electric treatment. This mechanical arrangement, however, is merely suggestive and no claim to invention relative thereto is made in this application.

The annexed drawing and the following description set forth in detail certain means and steps illustrating and embodying my invention, the disclosed means and steps,

however, constituting but one of the various forms in which the principle of the invention may be applied and by which it may be carried out.

In said annexed drawing:

Figure 1 represents an arrangement of apparatus which serves as an illustration of means by which my improved process can be carried out with reference to an open-hearth product, there being disclosed in dotted lines the progress of the electrodes as the same are raised gradually during the tapping of the furnace, such dotted lines illustrating the practice when the electric treatment is commenced as the steel and additions enter the ladle, which is one of the forms of the improved process comprehended by the spirit of my invention;

Fig- 2 is illustrative of the conditions when dealing with an open-hearth product, immediately following the finishing of the tapping and immediately prior to the lowering of the electrodes with the cover; and

Fig. 3 represents an arrangement of apparatus which serves as an illustration of means by which my improved process can be carried out in connection with the operation of a Bessemer-converter.

With particular reference to Figs. 1 and 2, an acid-lined ladle of the usual construction is represented by 1, mounted upon a truck 2 which is adapted to be brought up to the open-hearth furnace .4 upon suitable rails in order to receive the product of said furnace, electrodes 3 suitably supported, and raised and lowered manually or by automatic means well-known in this art, being provided for putting the products contained in the ladle into the electric circuit. These electrodes 3 extend and play through a ladle cover 5, Fig. 1, which is applied as soon as the charge has been tapped from the openhearth 4 into the ladle 1, or which, Fig. 2,

is secured to the electrodes 3, if desired, and is raised and lowered with the electrodes.

.With particular reference to Fig. 3, the conditions are shown in connection with the carrying out of a duplex Bessemer-converter electric treatment process, the difference between Figs. 1 and 3 being that the dotted line position of the electrodes, indicating the introduction of the same as soon as the charge is commenced to be poured, is omitted in Fig. 3. ,This last-named condition, suggested by the dotted lines, Fig. 1, is merely one of the methods of carrying out my invention and it is not intended by illustrating the same in Fig. 1 that this method is the invariable or even the preferred one.

While the furnace product is beingtapped or poured into the ladle 1,I add the desired alloys, in acold state, if desired, gradually to the steel stream from a container 6, such alloys being in pure form, or in the form of-ferro alloys, etc., as is referable and desirable, and also prefera 'ly crushed. The alloys which I mean and hereinafter claim as desired alloys are those in which the losses are greatly reduced by reason of adding the same when and as added by my process and definite percentages of which are desired in the final product and are principally chromium, manganese, tungsten, aluminum, silicon, vanadium, molybdenum, and combination of them, or combinations of one or more of these alloys with other additions. Of course, other alloys or a combination of them may be added for purposes other than to secure definite percentages thereof in the final product, such as, for quieting the steel by their affinity for oxygen or other impurities, thus cleansing the bath and making the product more homogeneous, and for performing other desired functions. Illustrative of such other alloys is titanium. Also, illustrative of some alloys of which definite percentages are desired in the final product and of which losses would not be reduced by my process,

because they are not subject to losses in the primary furnace, is nickel. Particularly in the case of chromium has it been found that when the addition is introduced into the primary furnace, usually at the time or just before tapping, there is a great variation in the product, the alloy being subject to fur nacereactions, causing it, among other results, to be oxidized and to go into the slag, so that large losses occur, sometimes in excess of thirty (30) per cent. of the amount of chromium introduced into the primary furnace. My improved process greatly reduces these losses, the atmosphere of the electric furnace being a neutral or a reducing one. In addition, my process insures a very uniform product. By my improved process also, even such an infusible alloy as chromium can be satisfactorily assimilated in a cold state, and it is not necessary to preheat the same and reduce it to a molten or semi-fluid condition. Thus, by my process,without previous cost and labor, except for grinding and powdering, a very infusible alloy, such as chromium, is added, while at atmospheric temperature, to steel of substantially three thousand degrees (3000) Fahrenheit higher temperature than the alloy and still a good distribution and combination is secured.

When the open-hearth furnace is tapped, all of the product is allowed to run therefrom, including the slag, and 1 preferably allow a little of the slag 7 to remain in the ladle 1 for the purpose of keeping the product hot, Fig. 2, the balance of the slag being allowed to run off over the ladle, or being otherwise removed therefrom, as is common practice; of course, in the case of the Bessemerconverter, Fig. 3, there will be only a slight amount of slag anyhow. I then apply the current to the mixture of steel and alloys which gives a motion to the bath, completes the obtaining of a proper mix, removes the minute cavities of slag that have arisen from internal chemical reactions, and effects the desired refining, such application of the current being for a comparatively short period, for instance, fifteen minutes, when treating a high-grade open-hearth product. Some of the incidental results of this electric treatment are the removal from the metal of some oxygen, the oxids going intothe slag, and the further purification from sulfur.

Particularly is my process applicable to the production of. chrome steel by the duplex open-hearth electric furnace method, overcoming the somewhat prevalent opinion that only either steel refined entirely by electric treatment or steel refined entirely by crucible treatment can be practicably manufactured and still meet the requirements of desirable chrome steel and prov-i ing that, an open-hearth treatment combined with an electric refinement, in a proc-, ess carried out in the manner hereinbefore detailed, will practicably produce a product meeting the requirements of desirable chrome steel.

It is well known that in the basic process of steel making a substantial amount of the phosphorus can always be removed. However, sulfur is more difficult and uncertain to control. Sometimes .apparently equivalent conditions will remove greatly varying percentages of sulfur. If I desire to re- .move additional sulfur in the ladle, by means other than temperature, which is al-.

ways a potent factor in eliminating sulfur,

, I remove from the ladle quickly the small amount of slag 7 heretofore mentioned, if it has been. allowed to remain in the ladle, and add'lim'e or a similar product, in,com-

. bination with fiuorspar, calcium chlorid or similar products which will increase the fusibility, if necessary, without lowering the basicity, tomake a satisfactorily basic slag,

which will not only remove some of the sulfur, butwill absorb the impurities and help in the refining by absorbing the oxidsfrom ahle steel, as would have been done also by t e small amount of furnace slag. Sometimes also, the cost of pure stocks, the detriment to the primary furnace roof, the damage caused by dust carried over to the ports and checkers, and the necessarily higher working temperatures, when removing sulfur 1n the primary furnace, make it advisable to remove much of the sulfur in the electric furnace rather than inthe primary furnace. The electric treatment is then applied. v

When my improved process comprehends the use of acid open-hearth steel, or Bessemer-converter steel, as manufactured in the-United States, it is presupposed that the phosphorus content of the original materials which are put into the open-hearth or converter is such as to insure the desired phosphorus content of the final product, in-

converters have been used, particularly in Europe, in which phosphorus and some sulfur have been removed by employing a slag formed from melted lime rock.

By the use of the process described above, 1

I obtain the results hereinbefore set out, of economically handling large tonnages and securing a satisfactorily clean and homogeneous product in which the additions are most uniformly'distributed and for which,

because of the comparatively small losses, less additions are required than in any procr ess heretofore known to me. Furthermore, the relative loss of heat through the walls is also less for an electric furnace giving large tonnages than for one giving comparatively small tonnages.

As plainly shown in Fig. 1, I do not limit myself to an application of the'electric treatment only after the product has been tapped or poured into the ladle, inasmuch as the conditions are often such in electric furnace treatment that the current may be safely and practicably applied as soon as the product has commenced to be poured into the electric furnace, as is well known to those skilled 'in this art. This method of applyplying the electric treatment is illustrated in dotted lines, Fig. 1, in which the dotted line position of the electrodes indicates how the latter are gradually raised as the ladle 1 is gradually filled with the charge and in which the position of the cover 5 shows how l the same is held above the ladle 1, until the whole charge is tapped into the ladle, the electrodes meanwhile being gradually drawn up through the cover 5, and then the latter lowered upon the ladle when .the whole charge has been tapped.

What I claim is:

1. In processes of manufacturing electric steel wherein the product of an open-hearth furnace, Bessemer-converter, etc., is refined, the steps which consist, in pouring such product from the furnace into a suitable receptacle; adding the desired alloys to .the product while being poured; and then subjecting the mixtureof steel and additions to electric treatment.

, 2. In processes of man'ufacturing electric chrome steel wherein the product of an open-hearth furnace is refined, the steps which consist, in tapping such product from the furnace into a suitable receptacle; adding ferro-chro-me to the product'while being. tapped and then subjecting the mixture 3 of steel and chromium to'elect-ric treatment.

3. In processes of manufacturing electric chrome steel wherein the product of an openhearth furnace is refined, the steps which consist, in tapping such product from the furnace into the ladle, allowing some of the slag to remain in the ladle to keep the metal hot; adding ferro-chrome to the product while being tapped; and then subjecting the mixture of steel and chromium to electric treatment for substantially fifteen minutes.

4. In processes of manufacturing electric steel wherein the product of an open-hearth furnace is refined, the steps which consist, in tapping such product from the furnace into a suitable receptacle; adding the desired alloys to the product while being tapped; adding lime or asimilar product to form a "satisfactorily basic slag; and then subjecting the mixture of steel and additions to electric treatment.

5. In processes of manufacturing electric steel wherein the product of an open-hearth furnace, Bessemer-converter, etc., is refined,

the steps which consist, in pouring such product from the furnace into a suitable receptacle; allowing some slag to remain in the receptacle to keep the metal hot; adding the desired alloys to the product while be1ng poured; removing the slag; adding lime or a similar product to form a satisfactorily basic slag; and then subjecting the mixture of steel and additions to electric treatment.

6. In processes of manufacturing electric chrome steel wherein the product of an openhearth furnace is refined, thesteps which consist, in tapping such product from the furnace into the ladle; adding ferro-chrome to the product while entering the ladle; adding lime or a similar product to form a satisfactorily basic slag; and then subjecting the mixture of steel and chromium to electric treatment.

7 In processes of manufacturing electric chrome steel wherein the product of an openhearth furnace is refined, the steps which consist, in tapping such product from the furnace into the ladle, allowing a small amount of the slag to remain in the ladle to I keep the metal hot; adding ferro-chrome to the product while entering the ladle; removing the slag; adding lime or a similar product to form a satisfactorily basic slag; and then subjecting the mixture of steel and chromium to electric treatment.

8. In processes of manufacturing electric steel wherein the product of an open-hearth furnace, Bessemer-converter, etc., is refined, the steps which consist, in pouring such product from the furnace into a suitable receptacle; adding desired cold alloys to the product while being poured; and then subjecting the mixture of steel and additions to electric treatment.

9. In processes of manufacturing electric chrome steel wherein the product of an openhearth furnace is refined, the stepswhich consist, in tapping such product Ii'oin the furnace into a suitable receptacle; adding cold crushed ferro-chrome to the product while being tapped; and then subjecting the mixture of steel and chromium to electric treatment.

10. In processes of manufacturing electric steel wherein the product of an open-hearth furnace, Bessemer-converter, etc., i refined, the steps which consist, in pouring such product from the furnace into a suitable receptacle; adding the desired alloys to the product while being poured; establishing an electriccurrent through the steel and additions as the same enter the receptacle; and continuing such electric treatment for a time after the whole charge has been poured into the receptacle.

' 11. In processes of manufacturing electric chrome steel wherein the product of an openhearth furnace is refined, the steps which consist, in tapping such product from the furnace into a suitable receptacle; adding ferro-chrome to the'product while the lat- I ter is entering the receptacle; and establishing an electric current through the steel and ferro-chrome as the same enter the receptacle and maintaining same for a comparatively short period.

12. In processes of manufacturing electric low-phosphorus chrome steel, the steps which consist, in creating, in a basic open-hearth furnace, steel of the desired low-phosphorus content; tapping such product from the furnace into a suitable receptacle; adding ferro-chrome to the product while being tapped; and then subjecting the mixture of steel and chromium to electric treatment.

13. In processes of manufacturing electric low-phosphorus chrome steel, the steps which consist, in creating, in a basic open-hearth furnace, steel of the desired low-phosphorus content; tapping such product from the furnace into a suitable receptacle; adding ferro-chrome to the product while being tapped; adding lime or a similar product to form a satisfactorily basic slag; and then subjecting the mixture of steel and chromium to electric treatment.

15. In processes of manufacturing electric low-phosphorus chrome steel, thesteps which consist, in creating, in a basic open-hearth furnace, steel of the desired low-phosphorus content; tapping such product from the to form a satisfactorily basic slag; and then furnace into a suitable receptacle, allowing subjecting the mixture of steel and chromium some of the slag to remain in the receptacle to electric treatment. a

to keep the metal hot; adding ferro-chrome Signed by me, this 15" day of March, 10 5 to the product While being tapped; removing 1919.

the slag; adding lime or a similar product JOHN MGCONNELL.

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