US3215424A

US3215424A - Apparatus for refining iron

Info

Publication number: US3215424A
Application number: US151918A
Authority: US
Inventors: Kanamori Kuro
Original assignee: Individual
Current assignee: Individual
Priority date: 1960-12-07
Filing date: 1961-11-13
Publication date: 1965-11-02
Anticipated expiration: 1982-11-02
Also published as: AT247889B; GB1004355A; DE1224341B; BE610957A

Description

Nov. 2, 1965 KURO KANAMORI APPARATUS FOR REFINING IRON Filed Nov. 13. 1963 INVENTOR. KURO KANAMORI BY A torney 1 United States Patent C) 3,215,424 APPARATUS FOR REFINING IRON Karo Kanamori, 36 Asagaya S-chorne, Suginami-ku, Tokyo, Japan Filed Nov. 13, 1961, Ser. No. 151,918 Claims priority, application Japan, Dec. 7, 1960, 35/ 47,802 1 Claim. (Cl, 266-34) The present invention relates to an apparatus for refining iron with oxygen or an oxygen-containing gas.

The primary object of the invention is to provide an apparatus for refining iron by continuously making slag and continuously removing slag, thereby causing active slag to contact continuously the surface of molten iron, while circulating said molten iron along the center line of annular path.

Another object of the invention is to provide an apparatus for refining iron comprising means to impart a controllable uniform circular fiow to the molten iron, while it is being exposed simultaneously to a reaction with a refining gas and/ or solids in the reaction chamber.

Yet another object of the invention is to impart the circular flow mentioned, to the molten metal in the reaction chamber mechanically.

Still another object of the invention is to impart the circular flow, mentioned, to the molten iron, by directing the refining gas and/or solids for reaction toward it in a directional stream in the reaction chamber.

Another object of the invention is to provide an apparatus for refining iron with means to adjust the velocity of fiow of the molten material mentioned within a predetermined range of zones.

Yet another object of the invention is to provide an apparatus of the kind mentioned, permitting the use and advantageous utilization of the solids used conventionally as slag-making and refining agents, in powder form either separated from or in mixture with the refining gases selected.

Still another object of the invention is to provide an apparatus for refining iron of the kind mentioned with means permitting introduction of the slag-making and refining agents.

Other objects of the invention will become clear from the following detailed description and accompanying drawings.

A preferred embodiment of the apparatus of this invention will now be explained with reference to the attached drawings.

FIG. 1 is a front view partly in perspective and partly in longitudinal section of a sample apparatus of this invention, and FIG. 2 is a cross section taken on line 22 of FIG. 1.

and it is preferable to use materials in powder form. The gas and the solids are used separately or as a mixture.

The refining chamber of an annular form is made by forming an annular space with refractory materials along 3,215,424 Patented Nov. 2, 1965 the circumference of a circle of the size selected depending upon specific conditions of operation, and the longitudinal sections of any positions of said space show the substantially same shape.

Although this annular space may be open towards the top, it is possible to form an annular space with a closed top made of refractory materials in a similar way, if desired or if occasions require. The refractory materials are generally covered by a steel shell, and an iron tapping hole, a slag running outlet, an exhaust pipe, nozzles and/ or a slag-removing stopper can be installed as desired. The molten iron is maintained in the annular space or the refining chamber and refined by making a circular motion.

In FIG. 1 and FIG. 2, the numerical figures 1, 3 and 4 show the lower part furnace body, the lower part steel shell and the lower part refractory materials, respectively. 5 represents the refining chamber and 6 represents the molten iron. 7, 8 and 9 show respectively, the upper part furnace body, the upper part steel shell and the upper part refractory materials. 10, 11 and 12 represent, respectively, the steel tapping hole, the slag removing outlet and the nozzles. 13, 14 and 15 represent, respectively, the exhaust pipe, the stopper for removing slags and the inlet for a molten metal. The arrow mark A shows the direction of the circulation of flow of the molten iron and slags.

A preferable method for reacting the gas and/ or solids with the molten iron is to provide over the surface of the molten metal one or several nozzles which are stationary or changeable in direction and position, and blow the gas and/ or solids over the surface of the molten metal or pour them into the molten metal from a direction aslant to said surface such as, for example, from the angle of 45 degrees.

According to this invention, it is possible to install a larger number of nozzles or inlets for blowing the refining gas and solids than in conventional converters and open-hearth furnaces. Therefore, not only is it possible to freely select the zones for blowing or adding materials for refining but also it is possible to greatly increase or decrease the quantity of materials to be blown into or to be added, with result that a very quick andrapid refining is made possible.

The position of the nozzles can be freely adjusted depending upon the kind of steel desired and on the conditions of refining. Therefore, when the slag is low in temperature, of high viscosity and hard to flow, the angle of the nozzles and the distance of their tips from the surface of the molten bath are adjustable to be switched to the so-called surface blow. In this way, CO in exhaust gas is burnt into CO and the temperature within the furnace above the molten iron is rapidly elevated with the result that the fluidity of slag is increased, and the removal of slag can be smoothly carried out.

Molten pig iron is first introduced through the inlet 15 into the furnace preheated by a burner. Oxygen is blown from the nozzles 12 into the molten pig iron, and the refining starts to take place by circulating the molten pig iron by the velocity energy of flow of the oxygen.

The advantageous effects arising from the refining according to this invention are hereinafter described.

The molten iron oxidized at the zone to which a refining gas such as, for example, an oxygen gas has been blown, and the produced slags move forward by the circular motion, and fresh molten iron, which has not yet been oxidized, continually moves forward to said zone where it is oxidized and then further moves on, and thus the circular motion is repeated until the refining is completed. In this way, a uniform oxidation of the molten iron is secured.

According to this invention, the temperature of the zone to which oxygen has been blown is not locally raised due to the circulation of the molten iron and slags, and thus it is possible to carry out the refining of iron by adjusting the temperature of the molten iron within a specific range, always pushing a white-heat point ahead.

Slag-making agents are added either through an inlet (not shown in the drawings) at a proper time or through the nozzles 12 together with the refining gas. The exhaust gas goes out of the exhaust pipe or stack 13.

In the course of the refining operation, slags only are caught by the stopper 14 and are removed from the outlet 11. The amount of slag which circulates with the molten iron and the amount of slag to be removed are increased or decreased in volume by adjusting the height of said stopper 14.

When a stopper is provided in the course of the circulation of the molten iron and slags, the molten iron will pass under the stopper and continue to take the circular motion, while the stopper is so constructed as to catch only the slags floating on the molten iron. It is thus possible to remove the produced slags continually or at any preferred time, as occasions may require. According to this method, it is possible to avoid the disadvantage of removing slag by discontinuing the refining operation as in the double slag-process carried out in the conventional converters, and therefore this method is very advantageous in the refining of pig iron such as, for example, one containing a high percentage of silicon or phosphorus.

When the molten iron and slag circulate, the slag is affected by the velocity energy of the gas which is over them and there will arise a ditference in the velocity of circulation between the slag and the molten metal, with the result that the interfacial reaction of the molten iron and slag takes place very actively. It is thus possible to combine an open-hearth furnace process with a converter process.

In case a closed refining chamber is employed, an exhaust gas passes through the inside of the furnace, circulating around the slag and the molten metal, and goes out of a stack. Consequently, the high heat which the gas possesses in the course of going through the inside of the annular furnace can be fully utilized for the refining itself. Aceording to this invention, therefore, thermal efficiency is greatly improved in comparison to the conventional converter process in which the gas is rapidly discharged from a steel bath to the outside of the furnace.

The progress of refining can be determined by taking analysis samples and measuring the temperature of the molten metal through said outlet and said inlet for adding slag-producing agents. Accordingly, the operation can be simultaneously controlled.

At the last stage of refining a deoxidizing agent is supplied through a proper inlet (not shown in the drawings) or with the stream of gas, and then steel is taken out of the steel tapping hole 10.

EXAMPLE I An annular furnace of 100 kg. capacity as shown in the drawings is used. The quantity of molten pig iron is 102 kg., and after the introduction of the molten iron into the furnace the blowing and refining start to take place at the temperature of 1290 C. The blowing and refining time is 11 minutes and 30 seconds in total, and pure oxygen is blown into the furnace from two nozzles. The pressure of oxygen is approximately 4-5 kg./cm. and the quantity is 0.62 m. /min. for the first 5 minutes, and 0.81 m. /min. for the rest of time and refining is carried out continuously. Towards the end of refining a part of slags is removed while refining. Samples of slags and the molten metal are taken from the slag removing outlet four times during the entire refining time as shown in Table I to determine the progress of refining.

As slag producing agents, 3.0 kg. of CaO and 0.6 kg. of CaF are supplied immediately after the starting of blowing and refining, and 4.0 kg. of CaO and 0.8 kg. of CaF are supplied after the lapse of 5 minutes and 30 seconds. 2.0 kg. of Fe-Mn powder is supplied as a deoxidizing agent after the lapse of 11 minutes from the starting.

Table I At the. 5 minutes 9 minutes At the time of la r later time of starting t pp 4. 26 2. 75 0. 37 0. 0s 1. 01 0. 36 0.33 trace 0. 91 0. 092 0.11 0. 320 0. 260 0. 068 0. 05s 0. 053 0. 014 0. 014 0. 004

As the result of this operation, 80.8 kg. of steel were obtained and the tapping temperature of steel was 1640 C.

EXAMPLE II The procedure of Example I is followed except that the quantity of oxygen is 0.60 m. min. constantly throughout the operation and the nozzles are placed a little closer to the face of the molten metal. The result is shown in Table II.

Table 11 At the 5 minutes 9 minutes At the time of ter later time of starting pp 4. 35 2. 74 0. 45 0. 10 0.85 0.31 0. 26 0. 2G 0. 92 0. 22 0. 053 0.31 0. 21 0. 04 0. ()6 Trace 0. 069 0. 038 0. 014 0. 004

As the result of this operation, 87.6 kg. of steel were obtained, and the tapping temperature of steel was 1640 C.

While refining was carried out in such a short period of time, it was also possible to completely avoid slopping by removing slags at proper times.

The oxidation of silicon, manganese, carbon etc. in the molten iron is regulated by their atfinity with oxygen and the temperature. In the conventional converters, oxidation sometimes concentrically takes place at the zone to which oxygen is blown, resulting in a difference in the degree of oxidation from other zones. According to this invention, since the refining operation is carried out while circulating the molten iron and slags, the white-heat point gradually moves forward and the molten iron is uniformly refined according to the oxidation step in metallurgy. This fact is particularly advantageous in the case of the refining of, for example, chromium-containing pig iron smelted from laterite ores.

As described above, this invention achieves very superior eifects which cannot be expected to be attained by the conventional apparatus.

The present specification describes examples of an invention for the purposes here disclosed. It is, however, intended to cover all changes and modifications of the embodiments shown which do not depart from the spirit and scope of the invention as claimed.

I claim:

A furnace comprising a hollow torus, conduit means for introducing molten metal into the torus and for removing m lt n metal therefrom, nozzle means extending into the hollow of the torus at an angle to the centerline thereof for introducing refining agents therein, an outlet for removing slag formed on the surface of the molten metal, and a barrier means supported within and extending radially of the torus adjacent said slag removing outlet and positioned to bar the passage of slag and allow the passage of molten metal past said barrier means.

References Cited by the Examiner UNITED STATES PATENTS 6 Greene 75-52 X Neuhauss 75-60 X Whiston 266-33 Geyer 75-61 X Alexandrovsky 75-60 Leroy et a1 75-52 X Rummel 75-93 FOREIGN PATENTS Great Britain.

252,046 10/12 Germany.

BENJAMIN HENKIN, Primary Examiner.

' RAY K. WINDHA'M, Examiner.