DE466755C - - Google Patents

Description

GERMAN EMPIRE

ISSUED OCTOBER 15, 1928

REICH PATENT OFFICE

PATENT LETTERING

JVl 466 755 CLASS 12 i GROUP 37

S j β462 IVj121 Date of the announcement of the grant of the patent: September 27 ig2 &

Societe Elektro-Metallurgique de Montricher in Montricher, Savoyeii, France. Process for electrothermal reduction Patented in the German Reich on July 28, 1926

The priority of filing in France from November 4 11) 25 ^{lbt m} claimed.

When performing electro-thermal reductions with or without simultaneous charring, the starting material has hitherto been mixed in indiscriminately and as evenly as possible abandoned the furnace to form the melt bed, whereby only care is taken to that the material does not come into contact with the fan nozzles. This in itself comfortable However, the preparation of the batch has disadvantages as a consequence.

There are great losses of starting material, sometimes reaching 200/0, a; on the other hand, the wear of the electrode is extremely extensive, so that the useful Electrical energy yield is hardly 500/0. As a result of secondary phenomena the end result of some working methods becomes inadequate !, and these are often impracticable. All of these shortcomings are essentially due to the uniformity of the melt bed, which has been achieved so far regarded as an essential requirement. This evenness is the cause of a Localization of the current in the immediate vicinity of the electrode, causing overheating are unavoidable, the starting material volatilizes, the electrode burns off quickly, electricity is excessively consumed. In addition, there is an inconvenience that the maintenance personnel are annoyed by heat radiation will.

With a reduction of material mixtures, the uniformity as a result of the

increase in the contact points of the material and its mutual molecular influence in addition, a more or less extensive slag formation, whereby it is often necessary, pure or carbonaceous Adding metal to the oxygen-containing metal.

For example, calcium carbide must be added to the quicklime, or silicon carbide to be added to silica, if in the latter case it is about the extraction of Silica lime acts.

The inadequacy of the uniform melt bed process thus makes it required to the overheating near the electrode and the slagging of certain To avoid parts of the loading, to arrange the feeding of the materials into the furnace in such a way that in the one to be treated Bulky carbonaceous ingredients are included to a side Scattering of the current emerging from the electrode as well as the mutual separation of the Substances that have a mutual molecular effect, as well as those substances which only contain reducing agents.

The method of the present invention is based on this finding. To this The purpose is conductive additives of constant or increased electrical permeability used by exclusive devolution of the carbonaceous substance and by ex-

equivalent additions of uniform or variable reducing substances accordingly the more or less complex end product. One of these additions is done in the usual way, i. H. continuous and on all bodies, while the other only racking and at regular intervals around the electrode.

ίο This method is generally applicable and has resulted in perfect durability of the electrode, abundance of tapping and the highest yield of the starting material. The main power amount goes nämlieh by the still solid mass, thereby being placed in a position occur without emulsions in the lower layers, to use electrodes of very large diameter and ¹ even to use the below befindliehen empty space to the product obtained do to purify. In addition, it is found that, unless intentionally excessive amounts are added, no part of it will pass through the network of conductive mixture and mix with the melt or other substances in the vicinity or with the end product itself, e.g. B. with the calcium carbide.

Despite the apparent complexity of the procedure due to the simultaneous use special electrode carrier and a new charging device for the following advantages:

a) Elimination of all local overheating and the resulting losses.

b) Extraction of end products, the content of which depends on the nature of the treated Corresponds to starting substances.

c) Production of direct alloys despite the mutual molecular action of the Starting material.

d) Possibility of using very high powers by means of a single electrode suitable diameter.

e) Due to the large diameter of the electrodes, the possibility of using metals and their alloys, which arise in the lateral parts of the furnace, in the extension to purify the electrodes.

The drawings illustrate exemplary embodiments of the invention.

Fig. Ι is a vertical section through an oven through a lower layer of cork is heated and with a melt bed of insufficient or inconsistent conductivity is loaded.

Figure 2 is a vertical section through the same furnace with loading accordingly the method of the invention.

Fig. 3 is a vertical section through a furnace with a mixture of carbon and neutral substance existing sole.

Figs. 4 and 5 show the arrangement of the feed hopper in vertical section and top view.

Fig. Ι shows a vertical section of a furnace that is heated by a lower layer of cork and whose charge consists of a uniform melt bed that contains the carbon necessary for reduction with or without simultaneous carburation, i.e. a melt bed with insufficient conductivity or, if it has metal chips are added, inconsistent conductivity. The current α goes directly from the electrode c to the bottom d exclusively through the central core e. The side parts b of the furnace do not receive any electricity. The conductivity of the core e has increased or stabilized by melting and transformation, and the heat generated by the passage of the current is localized on that part of the furnace which needs it least, since this part is the more advanced in terms of transformation. This inexpedient use of the current leads to the unavoidable result that the electrode and the neighboring substances or the substances that have slipped downwards are overheated, and this explains the side effects of volatilization and combustion in the open air, which are all the more evident , as carbon dioxide evolves and is inadequately dissipated in the same inadequate manner as the current itself, which is known to result in excessive loss and consumption, and to make approach to the furnace nearly impossible.

In the furnace of Fig. 2, in which the present invention is applied, this is charged with a mixture, the conductivity of which is increased or stabilized by the fact that it contains the total amount of carbonaceous material which is necessary for complete reduction. The mixture is supplemented at regular intervals by adding material to be reduced, which is then poured around the electrode. In contrast to the process in Fig. 1 here the stream enters α from the electrode c as soon as it comes into contact with the under treatment material scatters as a result of the additions /, which serve as insulating deflection walls, g to the wall and reaches the oven floor d only after the total amount of mixture h has passed through.

This broadening of the current cone increases with the increase in the number of carbonaceous ones Admixture to the "Leil-anisierung and

with the amount of additives and can go up to the complete disappearance of the current run below the electrode. This way you can local overheating and bring their disadvantages in elimination and at the same time the complete reduction in the Gap between the electrode and the furnace wall, which is the indispensable prerequisite for the purification of the products that accumulate on the oven floor. Simultaneously but as a result of the cone-shaped embankment around the electrode one achieves that the carbon monoxide is thrown against the furnace wall, where there is a considerable amount Gives off heat and possibly even contributes to the reduction itself.

With the most favorable distribution of the current, pure products are obtained and the greater the diameter of the, the more favorable the efficiency of the carbon monoxide Electrode and the thickness of the charge over the molten bath «; the former reduces the Crash of the new materials in d'as melt pool, the latter lengthens the cooling time and the oxidation of the gases evolving from the surface layers. The entirety of the merits of the present Procedures only come into play when one of the usual units, which is hardly 50,000 A., disregards and double and even quadruple the intensity units AVertes falls back, so that, as the electrode and melt take on a larger circumference, premature material crashes can be disregarded and without risk for the utility value of the slag nor for the refining of the metal one determines the thickness of the Charge can increase in an advantageous manner.

Fig. 3 illustrates a vertical section through a furnace 200000-240000 A. in normal passage of the reduction and simultaneous purification is with a sole consisting of a mixture of carbon and neutral substance i /. The electrode c protects the slag and the metal / against accidental effects of the mixture h and the additives /; it is increased by the total part of the cross-section which arises as a result of the reduction in the current density, which goes down from 4 or 5 amps, as is usual, to 2 amps per square meter.

Fig. 3 also provides evidence that such high current intensities can only be used if one dispenses with homogeneous melt beds and uses heterogeneous melt beds according to the present invention, which offer the possibility of lateral reduction. Since an electrode of 200,000 to 240,000 A. must have a diameter of at least 2.5 m, it is easy to foresee the difficulties and disturbances that will arise when one is forced to push the material to be treated up to the central core in order to get it to the direct action of the current, which occurs exclusively at this point, and if so, then the developing carbon oxide must pass through the new and the molten material, emulsifying them.

Undoubtedly, 'd'as means the present method as a result of the very high current intensities the increase of the yields, besides the possibility to use the alloys directly to obtain from their oxides what has hitherto only been possible with the use of expensive means was possible, and finally the purging of those accumulating under the electrode Products: carbide, sulphide, cement etc. This refining is for certain metals: iron, Manganese, chromium, etc., even synonymous with refinement, since the oxidizing effect the additives is significantly increased. This effect comes immediately below the reduction ring due to the extremely fine distribution of the metal at the moment its emergence and as a result of very high temperature on the basis of relative Infusibility of the conductive mixture. Of course, it is a prerequisite that that a suitable choice is made among the various electrode systems, who in general behaved quite well under the previous conditions, but are still not always suitable for all cases.

For very high temperature manufacturing methods with or without metal carbides, which decompose in the lower part of the reduction ring and regress below the electrode to damage it, can, as the length of the electrode wear is just as significant as in width, use a continuous or uniform electrode system. It is there is no need to fear that the melt will suffer a dangerous constriction, on the other hand in the case of manufacturing methods with medium temperature, in which dismantling is not no occurs, one is forced, since the wear only takes place on the sides, a discontinuous one or to use a split electrode system that makes the replacement of the used parts of the electrode more suitable Time allows to keep their scope to the minimum for a satisfactory operation.

With regard to the production of the conductive mixtures, as a result of the diversity of cases only establish a minimum rule that the carbonaceous material

must have twice the volume of the supplementary starting material with the exclusion of the Metallspkne, their leakage instability makes them electrically indifferent, so that the spongy mass of the metal carbides and of free carbon is always available in sufficient quantity. This is for the right one Scattering the current and for the sharp mutual separation of the additives is essential necessary. The additions, as already explained, are prevented prematurely to get to the oven floor, be it individually or in admixture or in molten form States with the products already formed: carbides, sulfides, etc., or in a molecular combination through mutual Action, slag d'er alloys, etc. The suspension of the reduction as a result premature subsidence can lead to certain losses, faulty production insufficient enrichment or you result in their composition.

To comply with this minimum rule, and although the volume of metal chips that to be added to the conductive mixture as a whole, is left unconsidered of course a carbon substance with the lowest possible density is necessary; divorce it without further ado from the anthracites of origin and the metallurgical hard cokes, Incidentally, the chemical action of which is too slow and insufficient conductivity to use gas coke and its homologues almost exclusively. Charcoal, despite its lightness, must be excluded because of its inadequate quality natural conductivity and its easy flammability in air every time the materials to be reduced in the molten State smoothly and are free of viscosity, which is the escape the reducing gas could affect e, and if the purity of the end products doesn't matter.

On the other hand, the ratio of two volumes of coke to approximately one volume of supplementary material, although generally sufficient, is only maintained in the case of heavy metals of the iron class, the ores of which contain only a limited reducing component, and for which an excessive addition of coke would require extensive amounts of supplementary material disturb the operation of the stove. In practice, one is usually led to exceed the three units in order to help spread the current by increasing the level of additives that act as baffles and the conductivity of the carbon mixtures; in complicated cases it is advantageous to use one of the reducing options. To incorporate materials into the mixtures entirely. Thus, the Minirnalregel with respect to the volumes of the coke and the supplementary materials for the mixtures requires correction meaning that the ratio can be increased depending on the furnace device and ^one the nature of the production up to four units, but without this enhancement for the remaining Starting materials may be more than twice the weight of the supplementary materials of the conductive mixtures for two half-hour additives, and three times that for three half-hour additives. The metal chips, as already mentioned, are not taken into account here.

In the most common cases, calcium carbide, manganese, silicon any Salary etc., practically the best results are achieved by balancing the weight between the conductive mixtures and the additions of the starting materials with the exclusion of coke and metal shavings. There there is an interest, if possible every hour when the high-performance units are running at full speed To undertake the tapping, it is advisable, if possible, to give up only two additives every half hour instead of three, because the latter only allow tapping every 1½ hours.

The following examples name the additional elements for advantageous use the new reduction method for all types of production in the electric furnace either simultaneous carburization or subsequent refining or refining.

I. Heterogeneous melt beds with conductive mixtures according to the minimah egel of the volumes.

First example

Iron: 10,000 kW / h, 45 volts, 1 electrode. Production per hourly tapping:

10,000 kW / h

7K ^

Corresponding starting materials:

Coke. . . . 5000 X 0.32 - ι 000 kg or 4000 1

Ore 5000 X 1.8 - 9000 - - 5000 1

Lime.. . 5000 X o, 22 -— ι ίου - - i22? L ¹¹⁵

Corresponding natural volumetric ratio:

coke

4000

Ore -j- lime '5 000 - (- 1222

0.64.

Corresponding conductive mixture:

Coke 160 kg or 4000 i

Ore 3000 - - 1666 1

Lime 366 - - 407 1

Changed volumetric ratio: Coke 4000

Ore -f lime "1666 + 407

Half-hourly supplements:
ί ore. 3,000

= 1.92.

\ fluctuating depending on

, I the lank that

First addition <! > for casting giau, fm

j T ^ - ,, rr ι semi-refined iron

i x \ .alK. 30O - I have to be black.

Second addition ^ ¹ V '3,000 kg I lime. . . 366 -.

II. Heterogeneous melt beds with weight compensation of the materials to be reduced between the conductive compounds and the additives:

First example

Calcium carbide 285 1, 10000 kW / h, 60 volts, ι electrode.

Production with hourly tapping:

10,000 kW / h

2 900 kW / h
Corresponding raw materials:

Coke ... 3448 X 0.75 = 2586 kg or 6465 1 Lime ... 3448x1.00 = 3448 - - 3831 1

Natural volumetric ratio:

₁₆₈ lime -3831 - ^{I; ö} ·

Conductive corresponding mixture: coke 3,448 kg or 6,465 1

lime

Changed volumetric ratio:

Coke 6,465

Lime ^: i9i5 ^ ^{3 <37} '

Half-hourly supplements:
First addition: lime .. 862 kgl fluctuating depending on

⁸ > de

the look of the

Second addition: lime. . 862 - } racking.

Corresponding raw materials:

Coke. . . . 833 X 0.89 - 741 kg or 1852 1 Lime .... 833 X 0.52 = 433 - - 481 1 Quartz ... 833x1.64 = 1365- - 1050 1

Natural volumetric ratio:

coke

Lime + quartz '481 + 1050

1852

- - 1.20.

Corresponding conductive mixture:

Coke 741 kg or 1 852 1

Lime 433 - - 4811

Changed volumetric ratio:
Coke_ 1852

Lime '481
Half-hourly supplements:

3.85.

siify · Diiir / FiRq Irrr) fluctuating, ever

sentence. yuarz 003 kg _{uacUdem bcnl} y _cke

J arises odei dei

Second addition: Quartz 683 - J ^Abst S ^elhaft

These examples are not of any restrictive significance, either with regard to the products or the stated proportions. These are closely related to the raw materials to be destroyed. They show especially the essential differences which wengistens if it is between the melting beds according to the present process and pass the previously customary, and the absolute necessity for high current intensities, the object of the conductive blends and ¹ of the additives perform mechanically.

One understands without further ado the impossibility of z. B. to put 3,000 kg of iron ore and 360 kg of ICalk in the furnace with the necessary speed and regularity, which are indispensable for the uniform distribution of the current and for the mutual separation of the masses to be reduced, even if an exaggerated number of Hiring people for it. For this reason, the invention includes not only the new reduction process and the head connection described, but at the same time also the device of special feed hoppers shown in Figs. They show the facility in section and in plan view. This is essentially characterized by an annular trough arranged concentrically around the electrode, which is subdivided as required. The vertical walls 2 cut off at the level of the floor of the compartments 3 for the mixture, and the obliquely extended floor extends into the spaces / between two successive flexible lines V which connect their supports χ to one another. The elongated nose 5 is connected by a central horizontal flap 6 with a compartment 7 for the additional material and by side flaps 8 with a counterweight with two tapping 9 which contain the conductive mixed material. The vertical flaps are each provided with a lever 10 to distribute the conductive mixture to the individual points of the reduction ring as required.

to let go; the flaps 6, however, are all by means of small articulated rods 11 with connected to a common cardan transmission 12, 'which is connected by a Zalin sector 13, an endless screw 14 and a common crank 15 is driven. Consequently can in the right moments, d. i. immediately after the first racking and then every half hour, the additives in a uniform manner and all at once, after the furnace overseer has given a sign and after the surface of the material being treated is smoothed has been abandoned.

The feed device is preferably made of metal. The arrangement of these Compartments and their emptying devices depend on the respective facility of the stove in question.

Claims (3)

Patent claims: i. Process for electrothermal reduction, characterized in that the hitherto customary homogeneous, randomly charged with the starting material Melting beds are replaced by methodically layered heterogeneous melting beds. 2. The method according to claim 1, characterized in that a first layer in is usually abandoned, which is necessary to carry out the procedure Contains carbon in its entirety, and a second task of non-conductive material, based on two or three additives is distributed in the immediate vicinity of the electrode in the furnace. 3. Feed device for the furnace for carrying out the method according to claim i, characterized by one arranged concentrically around the electrode Ring trough, which is divided inside so that on two compartments for the conductive material mixture a compartment for the additional material comes, and each of these three The existing group is divided into a common feed chute, which is separated by two vertical ones controlled outlet flaps for the material mixing and with a horizontal one Flap for the material addition ^ is provided, with all horizontal flaps be controlled collectively. 1 sheet of drawings