DE1508032A1 - Process for the reduction of ores by metallurgical means - Google Patents

Description

WOASTRASSE 24 1508032

A 1o 298

July 20, 1966

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INSTITUT DE RECHERCHKS DE IA SIDERUROIE FRAHCAISE

185 “rue President Roosevelt, Saint-Germain-en-Laye (Seine-et-Oise), France

Process for reducing Erien to metallurgical

Ways.

Bio invention relates to the electrometallic reduction of sreen in electronic ovens. She concerns in particular the direct production of cast iron or steel of the usual composition from iron ores or their agglomerated

Ea are already an Anssahl electrothermal reduction ««

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ORIGINAL INSPECTfO

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method known to Erse using an electric arc However, these previously known methods are very dependent on the power of the arc is bestirnt by the but available stroa.

The invention was therefore based on the object of these previously known Processes, especially those in which reducing hydrocarbons are put into the furnace Zone of the arc to be introduced * su improve.

In the case of electro-metallurgical reduction processes »in those a batch of oxide is passed through a heatable beduction zone in which you come from another furnace section, - in the final stage of the process, the Srs and an arc is generated - reducing aase flow in the opposite direction before the batch passes this section » in which they are soaked and their reduction is ended, achieved, this invention is achieved by the fact that the arc of at least one flaea torch sucks is used by which reducing agents are introduced.

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In connection with the features mentioned above, according to the invention the reducing agents introduced through the plasma torch are gaseous hydrocarbons such as hydrogen gas or also be liquid hydrocarbons atomized in a carrier gas, the carrier gas being gaseous hydrocarbons or containing oxygen © Oase can be used. In addition, in the zone in which in the power amplifier is melted, an additional reducing agent may be added which is not introduced by the plasma torch will.

The method according to the invention is preferably applied to the Reduction of a continuous beIe and reduction zone applied batch of agglomerated iron ore. In this case it can

a) the batch containing the ore to be reduced is agglomerated and transferred to the heating system without prior cooling and reductone zone are introduced,

b) agglomeration of the batch under oxidizing conditions to be executed

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c) the agglomerate is in the form of Ktigelohen.

The method for carrying out the method according to the invention developed device includes "

one with means of tapping metal and varnish adorned crucible,

at least one associated with the crucible Space for thermal and chemical exchange processes, whose establishment the passage of the au redueing Oharge and their entry in the Schmelstiegel allowed, while it is flowed through on the same side by the oases escaping from the crucible,

at least one plasma torch arranged in the crucible sur Suction of a large lunge arc between the torch and metal bath connected to means for supplying reducing agents.

The invention can be embodied in a particular embodiment can be applied to an electrically operated shaft furnace eur reduction, in which the classic elec.

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the but erseugung an electric arc by Plaeaabrenner (torches a plasma) are first · The invention However, the procedure can also take into account spatial conditions and the results achieved other technological designs are used For example, an electric furnace can be provided in which the electrodes are heated by plasma torches setst are and which is fed by a rotary kiln, in which the charge is pre-reduced by the Oas escaping from the electric furnace.

The use of plasma torches instead of ordinary ones Electric arcs in crucibles from SohmelB metallurgical or reduction furnaces are known. Jedooh is the plasma in the previously known forms of application either in aisles of the oar under the burner or for direct thermal or chemical action on the liquid, directly under the Plasma torch arranged bath used.

Bas according to the invention provides the use of Plasma torches in a reduction furnace, in which the su reducing metal-containing charge before reaching dee

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Crucible a stream of reducing, from the Crucible i.e. escaping from the arc zone Oasis is led towards. . In this way, the reduction reaction is started before the batch is in Crucible is and becomes - just like the Scheele process and the separation of the liquid phases slag and metal in the zone of the arc is ended.

The compounds necessary for the reduction or a substantial proportion of them are in the cutting crucible through at least a plasma torch was introduced to replace the classic electrodes subjected to an electrical discharge, which causes the formation of the plasma and, under the action of this, the reducing agent in one especially for the reduction process appropriate state to be transferred. Particular beneficial Methane (natural gas) has proven to be a reducing agent. This gas is perfectly suitable for feeding the plasma torch, in which it experiences strong ionization. The Saa is brought to a very high temperature and thereby completely cracked into elemental carbon and hydrogen * The ionized hydrogen emerging from the burner contains a substantial proportion of free atoms (Mo-

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noatomarer Waeeeratoff) which with regard to its effect ale Reducing agent is particularly active. If, depending on the nature the charge to be reduced, the amount of carbon / hydrogen formed from the natural gas is not sufficient, it is possible to determine the amount of the two components by producing some of the methane by fuel or reIeOil, which is atomized in the methane and is transported by it. The fuel or heating oil is in the same way as the methane duroh the passage Plasma torch arc cracked and ionized. Besides that It is also possible as an additional reducing agent To add carbon, for example Kok β β deaf, which is either suspended in the natural gas via the plasma torch or the crucible directly e.B. is fed under the action of gravity.

An essential advantage in the implementation according to the invention of the method is seen in the fact that the use of the plasma torch increases the voltage of the arc can be. The voltage can be several hundred volts and with special types of plasma torches can even reach 1,500 to 2,000 volts. This advantage is very important because the low tension of the classic

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Arcs their performance with consideration of the expended prohibitive amperage is very restrictive. This restriction has been very unfavorable to this day Reductions in shaft furnaces have an effect »which require very high energy for large production units.

Another advantage that the use of plasma torches brings with it is the possibility of maintaining the amount of reducing gas and the supply of heat independently of one another and regulating it separately introduced at high temperature and at the same time emitted thermal energy · In addition, it is nooh possible to add a very high temperature reducing gas to this air or oxygen, whereby a Gee is obtained that contains hydrogen, carbon monoxide and optionally carbon. Vm the amount of hot gas bu without using more of the reducing gas, an inert gas, for example nitrogen, can also be added.

In a particularly advantageous embodiment of the

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three Piasna burners are located vertically above the bathroom Arranged in the same way as classical electrodes, with the difference that the distance from the bath is different and that the electrodes of a Srelphasenweohselstrron be fed. The high temperature gas jets emanating from the burners hit the surface of the bath, so that the circuit is closed over the bath. You can of course also use other burners to be ordered. For example, they can be inclined in such a way that the arches form a single one the bath located point susanuentreffen. They can also be arranged horizontally opposite one another to extend beyond the lake be. In the last two cases mentioned, the 8tron flows directly into the burners without going through the bath, see below walk.

The method according to the invention is to be explained in more detail on the basis of an embodiment shown in Figures 1 to 3 «

Pig. I provide a longitudinal unit of an electric reduction furnace according to the invention)

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fig. 2 let a section through one placed in oven Plasma torch and

fig. 3 is an electrical circuit diagram for powering the plasma torches.

fig. 1 shows the different parts of an electric shaft furnace in which the method according to the invention is carried out. As is generally the case, the idea furnace consists of an extended refractory base 1 in which there is a liquid metal bath 2 which is covered with a tube 3. Der'Ofen is covered with a classic vault 4, which has three openings in which fire-resistant, sealed Durohlaßringe rings

5 of high mechanical and electrical resistance are attached, which can optionally be cooled by flowing water and which serve as a Form an isolated passage for three plasma torches 6 su, which will be described in detail later.

The furnace is generally of an elongated oval shape XW.Ü has at each of its extreme ends a shaft tower 7a and 7b, the upper edge of which reduces the ssu

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Beer batch is introduced. The three plasma torches Bind ewisehen the towers arranged in series as in certain reduction furnaces with conventional electric arcs. Such an arrangement has the advantage that it allows to keep the vault of the furnace free and to facilitate the feeding and movement of the burner bu, which is at The relatively high voltage would otherwise give rise to certain technological problems. This arrangement allows equilateral, the surface of the bath below the burner from that of the Sohaohttürme as the pole of the Angle of repose near the material to be reduced to keep clear, which facilitates the formation of an arc of great length.

The shaft towers 7a and 7b are at their upper end closed by OlookenBysterne 8a and 8b, like one too used in the gout of blast furnaces. As with the blast furnaces, the oasis can be reached by pipes 9a and 9b escape.

In the example described here, there was no special one Take precaution regarding the tightness of the DurohlaBring for the plasma torch through the vault

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seized «. Since, in principle, movements in the vertical direction hardly necessary ninfl, the leeway is on one for an expansion is reduced to a minimum, so that gas loss through Ami flows is kept low. Another option is to use the Durchlafiring e completely by a known telescopic Diohtungsvorrichtung to replace, where water or oil is used for sealing and when using the necessary measures for electrical insulation dee Plasma torch must be taken.

For example, the device described in French patent specification No. 1 418 153 can be used the application of which is clear to any person skilled in the art.

The sole 1 or the crucible is of course with the the usual tapping openings for metal and slag, which are not shown here.

The plasma torch used in the process according to the invention is to be described in detail with the aid of FIG. The carrion is in a cylindrical pipe fed, the In a converging and subsequently

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BATH ORIGINAL

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diverging pipe 11 ends * In the axis of the line Io and of the tube 11 there is a cylindrical electrode 12 which is insulated from the walls of the line Io. These walls are formed by a tube 13, the part a cooling jacket 14 through which water flows, which cools the entire burner. Dao converging and then diverging tube 11 is made of solid copper or Broneβ and also belongs to the cooling system to to participate in good cooling. It is therefore screwed directly onto the tubes 13 and 14. The flow of cooling water takes place in a tube 15, weloheβ the space divided between the tubes 13 and 14.

The electrode 12 is held in the axis of the device by means of insulating perforated supports 16, from those in Flg. 2 only one can be soldered. The electrode 12 is preferably hollow.DiM is used to make the arc connections, e.g. to add heating oil, which has the advantage of very energetic cooling at the same time. ALn electrode A non-oxidizable tube made of steel or copper can be used. If a solid electrode is used, this can for example made of carbon or tungsten.

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The energy supply takes place in three phases in such a way that each of the electrodes 2 of the torch is connected in one phase as in conventional electric arc furnaces. The main difference is that the voltage is much higher and can be 1,000 to 2,000 effective volts. The Erdjing can be done over the kiln mass. An increased potential difference is maintained between the electrode 12 and the tube 11 in order to generate an ionizing discharge in the oas circulating in the tube 11, the meaning of which will be explained later. In general, this voltage will be higher than the voltage of the arc between electrode 12 and the bath. In order to have an acceptable tension between the pipe 11 and the mass, the one in Tig. operate described branch, which symbolically represents the transformer for the supply of the furnace. The three electrodes are connected to three main secondary phases A, B, 0, and the corresponding bores 11 are connected to three secondary auxiliary phases a, b, o. For each burner, the voltage of the auxiliary phase is added to the voltage of the main phase. The primary winding of the transformer has a triangular branch, as is generally the case with furnace transformers.

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The burner has the puncture at the level of the nose below to take over · Dan in the line 1o under oinoin pressure of 6 bar, for example. «Gao is in the pipe relaxed, thereby increasing the speed. That Tube 11 is calculated so that the speed at its upper end is the speed of sound and at its diverging part reached supersonic speed. An electrical discharge therefore takes place in the divergent Part between the tube 11 and the electrode 12 instead. As a result of the low pressure and the high speed with a simultaneous sharp drop in temperature the discharge takes place in the entire volume of the diverging light and causes a strong ionization of the Gas. A strongly ionized gas jet therefore emerges from the burner and hits the Surface of the bath. The creation and maintenance of the arc between the electrode and the bathroom is very simple. When generating the arcs, the excitation is facilitated by the fact that the burners are brought closer to the bath without coming into contact with it to come, which is inevitable in a furnace with conventional electrodes. The distance between the oven and the bathroom during the l -, .. i execution of the procedure is normal-

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wedoe a meter or more. You stabilize the Currents are made by inductances of suitable strength, not shown in the figure and with the phases A, B, β and β, b, c are in series. The energy in the pipe 11 is only small. It is less than 1 / Io der Energy of the arc.

Electrode 12, which is difficult to cool, is subject to only slow wear and tear, which is slow

Qu

FaehaJleber of the tube forming the electrode inside of the burner is compensated. It is not necessary to see the extreme end of the burner. hit A little practice is enough to shape the shape with an oscilloscope of the discharge current between the tube 11 and the electrode zv. check with sufficient accuracy the To recognize the position of the extreme end of the electrode.

Using the following example, the production of a melt from an iron ore agglomerate is intended to be the following Composition are described

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Buttocks. $ 61.3

Pe ¹ " ¹ * .. 7.6 y>

JJiO ₂ .. 4.13 i>

MgO ...... 1.25 1 »

MnO. . ,,, 3, oo #

DNA agglomerate was directly after the agglomeration without cooling vorherguhonde In abgeblldetun not warmetoalLtrtntan Ddt tlbnr th the SchachttUrmo 7a and fön registered in the O 7b. The total volume of the shaft towers is P KubLk mettir, where P means the overall production άαα furnace ”and is expressed in tons / hour.

The agglomerate sinking in the Bohaohttürme is reduced by the hot reduction gauze rising from the crucible. The effectiveness of this aase was such that in the upper part of the Sohacht Tower the volume ratio carbon monoxide t carbon dioxide => 1 and the volume ratio Wanoer t hydrogen = 1.42.

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BATH

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Write in dan furnace forms the reducierte Agglot öimm oohrägen Bohlittwinkel before it is added to and liaeh mn dom flUoolgen Had, completed In WEL · tüum animal UohmalzproseU and the reduction and ill "On U'uimung dor two liquid phases and metal ilchluokö ilui »T) is carried out.

I) Io Followilo TuböLLo, in which some on a ton

Related values are divided into »should the and performance of the inventor ITor lead zo Igen ι

the PLauniabranner introduced

He bhannonga 15 ο Nm *

tiuroh <Ho electrodes of the burner

“Hiinge on loan oil 150 pounds

consumed the drenners
elektrlofihd energy 1.11ο KWk

erisdugte 8oh »eUe Sl .. ··· .... o, 5 t

Ma 2, o i

O 4, o i

Temperature .. 1,4oo ° E

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generated gas .. _r . .... ·· ... ·. «..... 640 Hot

Oo 18 Ji

CO ₂ 18 +

H ₂ 26.5 Ji

H ₂ 0 37.5 *

The example given above is the method of the invention, which of course can also be carried out in other ways, in no way restrict. The procedure The invention can in particular also be applied to those in French patent specification 1,249,437 and the USA patent specification 3 159 7o2 "cold" version * »was used will.

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Claims (2)

A 1o 298 Sun. July f966 a - ne patent application 1. Process for the reduction of screen to electroaetallurglsehea Ways "bei de" an Oxide batch is led through a resilient reduction zone, in which you come from one other furnace section - in dea in an output stage daa The process melts the Srs and creates an electric arc is - reducing oasis opposite beror the batch this billing, in de «ale oohaolBen and their reduction is terminated, achieved that a d u r ο h indicates that the arc of aindeatene a "Plaaaabrennar is caused by which Reduction olds are introduced. 2. The method according to claim 1, characterized in that dae those introduced by the plasma burner Reducing agent free coal substances, belspielsweiae natural gas, aixtd 3 · The method according to claim 1 »characterized in that the slide introduced by the flaea burner Reducing agent was put into a porter 909841/0623. ₂₁ . Α .. 298 ^{ΙίιΟϋ (} ' ^:} 2 2ο. July! 966
a - me fillet] Ige Kohlnnv / üSBeretoffe ulnd, 4y / learn »after Aiujprllchen 1 and 5, il ii il u ρ ο h υ ο k β η η κ θ L ahnet; » that (Inn TrHgergau »in jjuijffk · · olger KohlonwuD.Juretoff did, ^r ), / experience nnoh ÄiuiprUohen I and J> J α du ν a h β ο knows β 1 β hn ο t, since (3 last l'rtitforga *! iiuuijuihoiT onbhiiit. 6, method me, "iiiem the vorhorguhonlou AnnprUnhrt, il> i duroh g η k β η η ζ ο I Chuut, duiJ in dl" is iJchffloLzzonu Jon furnace a zunlltRilohou UodukUouiJuiLthil ulngofUhrb, dao not Aon Pliiumabeennor <> la ütrümb, 7, ancestors according to one of the preceding Anuprtluho, <1 a <■ · you roh gekennee pays »that the batch containing aggionmi'Lurt and without previous cooling is brought into the heatable Hudukhlonußimo oLn · 0 »yorfnhron tifioh otnom the preceding claim« »<i n 9 0 9 0 4 1/0 6 2: i - BAO ORIGINAL July 20th, 1966 / ι you ι »ο hg ο k ο η ii f, ο i ο h η β fc> that the agglomeration of the charge takes place in the oxide living conditions * *) »Procedure after an anoprllohe preceding one dot *, d a d ti ι * ο h ι; ο k ο η η 3 β I c h η ο t that the öhargo au KHgolohtm aiKglomorLiirb will, lt>, moktfleohor oven eur DiirohfUhrung doe ancestor according to Atiopi'uoh I, il a il ur "Ii g a k ♦) η η ζ e I ο h η β fc," let or ί> 1ηοη iiib HLfctuLu aum AbubLoh of Mt) ball and slag Oohrao Iz blogo L, uLnon lulb tlluaom bar In connection β agenden \ li \\ i \ λμ bhoiiiiLunhon and titiomloohen Aus taueohvorgänge, "loose blooming don the passage of the to be reduced"> fJhargo and its entry in the Sohaelstiegel allowed " [£ v; lihrond er glelohzelbig? On the _x yoiohsmden Oaoon durwohnrUmb is, '' m Inddiitan »olnon Flaea burner arranged in the i'logel for ο Iji) ü IjLcU t; hog mo groüor lung ewlaohen Bronner MiJtallhn <l, dor mLfc Hlbboln aur supply of Redukblono aa I nt ;, aufwelot, BATH ORIGINAL