US1140550A - Process for making steel. - Google Patents

Description

G. E. WEISSENBURGER.

PROCESS FOR MAKING STEEL.

APPLICATION FILED FEB. 29. 1912.

1,140,550 E Patented May 25,1915.

STATES GEORGE E. WEISSENBURGEB, OF BERLIN, GERMANY, ASSIGNOR 0F ONE-HALF TO OTIS ELEVATOR COMPANY, 0F NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

PROCESS FOR MAKING STEEL.

Specification of Letters Patent.

Patented May 25, 1915.

To all whom 'it may concern Be it known that I, GEORGE E. WEIssEN- BURGER, a citizen of the United States, residing at Berlin, Germany, have invented certain new and useful Improvements in Processes for Making Steel, of which the following is a full, clear, and, exact specification.

The invention relates to an improved process in making steel, and particularly to an improved process and furnace adapted for making steel castings.

The primary object of the invention is to .provide an improved process of making steel of the character herein described, and which is adapted to permit the use of a large percentage of steel scrap and pig iron possessing a less quantity of silicon in its composition thanl has heretofore been found permissible to use in Bessemer converters of either the bottom or side blow type and yet obtain steel suficiently high in temperature to successfully cast delicate and intricate shapes.

To the attainment of these ends and the accomplishment of other. new and useful objects, as will appear, the invention consists in the featuresof novelty, in the construction, combination and arrangement of the several parts hereinafter more fully described and claimed, and shown in the accompanying drawings, in which- Figure 1 is a vertical section through the center of the furnace taken at right angles to the axis on which the converter ismounted; Fig. 2 shows a plan view of the forward part of the furnace and a horizontal sectional view of the rear portion.

The furnace may be of the vcommon form or shape and of the tilting type. The walls of the same, indicated by the reference numeral 1, are constructed of material commonly used for such pur oses and old and well known in the art( n opening is provided at the top of the furnace through which the metal may be charged into it, and is provided with a suitablecovering or door 2, hinged or otherwise secured to the walls of the furnace. A discharge spout 3 is provided for withdrawing the metal after being converted into steel. The sidesof the furnace are provided with suitable trunnions firmly secured thereto and forming the axis on which the furnace is pivotally mounted. The trunnions 4 and 5 are rotatably secured in suitable bearings 6 and 7 on the upright supporting members 8 and 9, which may be of any desired form or construction. In the present embodiment the furnace is illustrated as the side blow type, and 1s provided with the usual set of twyers 10. A suitable pipe or passage 11 communicates with the twyers 10, and in order that the furnace may be freely rotated this pipe o r passage 11 iseXtended to a line at the side of the furnace coinciding with the extended axis, accordingv to the construction well known in'converters of this character. The supply-pipe 11 is provided with a suitable gate valve or other suitable controlling means, and in the present embodiment of the invention is shown as a branch of the pipe or tube 13 which coincides with the extended axis of the furnacel and isprovided with another branch 14 extending upwardly over the top of the furnace on the side adjacent to the spout 3. This pipe 14 is also provided with a suitable gate valve or control 15. The pipe connects with twyers 16 which enter the interior of the furnace far above the surface of the metal as illustrated, while the set of twyers 10 first described are located only slightly above the surface of the metal, so that the air admitted through them will strike the metal. The twyers 10 may be of any desired number and likewise as many of the twyers 16 as desired may be employed, although in the present embodiment only two are shown. The twyers 16 are preferably provided as shown in the embodiment with suitable oil or gas burners 17, one of. such burnersbeing adjacent to each of the twyers, and each of the burners 17 may be fed from a common source of supply, as the feed pipe 18 which leads into the common header or connecting pipe 19. Air to the twyers' 10 is supplied through the pipe 11, and the pipe 14 being also a branch of the pipe 13, receives its supply of air from the same source las the pipe 11, and although this is a convenient construction, it will be apparent that each set 'of the twyers 10 and 16 may receive its air supply from independent sources, if desirable. The gas or oil burners 17 are each provided with individual controlling means 17a.

Having set forth the construction of a furnace that may be used, its mode of operation in the improved process of making steel-:will now be described.

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It has been found preferable, although not essential, to first heat the furnace by the combustion of oil or gas, admitted through the twyers 16. The metal is then charged into the furnace either in the solid state, or part of it in the solidstate and the remainder in the molten state, or, if desired, all of it may-be melted before being charged intothe furnace. Air and oil, or gas, of the proper proportions and under the most desirable pressure for economic combustion are then admitted through the twyers 16 by means of the gate valve 15 and the burner controlling means 17a, until the molten material has reached the temperature where'the oxidation of silicon begins to take place. Air is then admitted through the twyers 10 by opening the gate valve 12, and the silicon and manganese in the molten material are rapidly removed by oxidation. If the oxidation of the silicon increases the temperature of the metal to a point Where the combustion of carbon takes place, the carbon will be eliminated after' the silicon and manganese, and if there is not sufficient silicon -in the molten material to raise the temperature to where the combustion of the carbon takes place, the additional temperature required may be supplied by the combustion of fuel admitted through twyers 16.

' After the combustion of carbon begins it is rapidly removed, after which the molten metal is ready to be re-carbonized' and poured into the molds.

Heretofore ithas been the practice to' re- ,duce the charge of metal in a cupola or melting furnace to a molten condition and then introduce it into aconverter; or the molten metal has been transferred directly from a blast furnace into a converter. Converters of the ordinary type a'reprovided with twyers for the admission of air in the form of a blast. When this blast of air is forced into the charge within the converter which necessaril must be rich in silicon, the oxidation o the silicon begins. This oxidation of the silicon raises the temperature of the charge until' the temperature reaches a point where the combustion of carbon begins, which further increases the temperature until the carbon is eliminated, after which the metal is ready to be recarbonized and poured into molds. In the process above described, if there be any manganese in the bath-or charge, it will be removed about the same time that the silicon is removed, and will aid the latter in raising the temperature. However, there must be sufcient silicon and man anese in the charge so that the oxidation o these elements will raise the temperature of the charge to a point where the oxidation of the carbon begins, otherwise when the air blast is introduced into the charge in the converter, it will chill the contents before the reduction of the carbon begins, thus causing a failure in converting the charge.

It is often very much desired to utilize considerable quantities of scrap metal l in making the steel, but it has often been found that when considerable quantities of scrap are used in the process described, such scra'p causes the amount of silicon in the charge to be lowered to such a point that when the silicon and manganese oxidize, the temperature is not raised sufficiently to cause the oxidation of the carbon and therefore conversion of the charge fails. In order to overcome this difficulty, the converter shown in the drawings is not'only provided with twyers for furnishing the air blast but also with twyers for burning oil or gas or other highly inflammable material. Therefore, instead of heating the charge in a cupola, which charge may include large quantities of scrap, it may be introduced directly into the converter, and by the use of the heating twyers, the temperature of the charge may be raised to any desired pointj before the Aair blast is turned on, so that'regardless of the amount of silicon. or manganese, or other easily oxidized elements in the charge, the ten1. perature of the charge may with certainty be brought to a point Where the oxidation of -the carbon begins. Then the heating twyers may be turned oif if desired, and the air blast introduced, and the converting process will proceed until completed, as the carbon having lonce begun to be oxidized, will continue to oxidize.v v

Materials such as silicon and manganese when a certain temperature is reached become oxidized, after which they are oxidizing agents with respect to the carbon which is oxidizable because at a still higher temperature the carbon is oxidized. The oxidizable carbon is oxidized more easily the greater the amount of silicon or manganese present' because then the" heat capable of being produced is greater and the amount of oxidizing agents such as the oxidized silicon and manganese is also greater.

It will therefore be seen that my irnproved process. consists in combining in one continuous operation, the open-hearth process and the Bessemer or converter process; both of these operations are carried on within a single device, namely, the converter into which the air blast is introduced preferablv after the heating twyers have been turned on for the requisite length of time. Although the heating twyers may be left turned on after the air blast begins to operate, it is preferred to first heat the charge 'tothe requisite temperature by the heating n chggeY until substantially all of the loxidizable agents have been eliminated by oxidation.

In testimony whereof I have signed my name to'this specification, in the presence of 15 two subscribing witnesses, on this 12th day of February A. D. 1912.

GEORGE E. WEISSENBURGER.

Witnesses WoLDnMAR HAUPT, HENRY HASPER.

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