DE2106570B2 - Method and device for the production of cast iron - Google Patents

Description

γ 3 4

piercing the slag causes what is obtained by using gangroineral alloys in the converter

one, rotary kiln is promoted. The use was received.

The device according to the invention is disadvantageous for the passage of calcium carbide as a reducing agent, since, on the one hand, the above-mentioned method is characterized by large amounts of calcium and, on the other hand, considerable amounts of electrical energy have to be supplied by an electric reduction furnace. Dip type with an uncovered bath for the production of Paher is the field of application of this well-known cast iron, the sole and walls of which are stitched with a fire process on high quality products with a low strength magnesia lining.
Carbon content limited, which can be sold directly The present invention encompasses in addition to the above, so that the manufacture of cast iron devices mentioned above prohibits certain other furnishing irons by this process. genes, which are preferably used at the same time

The object of the invention is therefore to provide a method and which are described in more detail below,

a device for the production of cast iron by using the shown in the drawings

Treating chromium- and iron-containing liquid preferred embodiments is the invention

To create slags of the above origin, the _1JS ; _{m the} following example explained in more detail,

the use of a classic and economical co- F i g. 1 shows a schematic partial section of the

Enabling lenstoffhaltigen reducing agents and according to the invention used electric furnace;

in a simple and convenient way to a cast iron F i g. 2 is a diagram showing the invention

Lühr, which explains a chromium content of 3 to 3.5% according to procedures.

It is easy to convert into steel and has a carbon footprint

has a fuel content of 3%, while extracting the residue nickel, one gets on the one hand a good

Chlack has an iron content in the range of 6 °. molten ferronickel, which is then converted into

A further object of the invention is to provide a control that is enriched and, on the other hand, a liquid one

tion of the depth of immersion of the electrodes in the slag, iron-rich slag.

so that the refractory cladding 25 This external slag is subjected to the invention of the furnace base and the furnace walls in a satisfactory process to remove the iron that behaves in it and the furnace and its electrical form is contained by oxides , to win,
see additional equipment to be arranged in such a way that the In order to do this, the slag is introduced in liquid aggregate equipment under the conditions of good functioning in an electric furnace with Soederberg electrodes functioning and the self-lining (car-30, with the transport e.g. with the help of from garnissage). Pans made with highly refractory silicon di-

The above-mentioned method according to the invention are lined with oxide aluminum oxide stones,
is now characterized in that the slag bath at the same time, or shortly before the slag is added to the electric reduction furnace, in which the is, a carbon-containing central zone of the cavity of the furnace is used to treat the reducing agent, the particle size of which is liquid according to the invention Slag is introduced, apart from measure below 50 mm, with 80% of the particles of a thin reducing agent layer being uncovered, the reducing agent having a grain size above the reducing agent, which is free of fluxes 0.15 mm. Due to this grain size, there is less than 8% volatile e ^; Only a relatively small part of the carbon material contains and a grain size below 50 mm. 40 substance-containing reducing agent violently with the in Due to its low density, the reducing agent floats progressively and separately from the slag surface of the bath and forms a glowing layer at the same time and / or between individual slag layers, which forms a protective screen that admits the loading processes, whereby the amount of 45 Loss of calories due to radiation is limited.
The reducing agent is chosen so that it meets the stoichio- The addition of the carbon-containing reduction-metric ratios of the simplest reducing agent, which the only addition to the electric furnace with reactions is sufficient, according to awien forms the entire added exception of the slag itself and the same-carbon serves on the one hand Carburizing the metal bath too early with the introduction of the slag, or as further a cast iron with a content of about 3% Koh- 5 ° above, between two successive fuel and, on the other hand, the oxygen deschickvorgangs takes place, can be over most of the metal oxides Extend the batch in sufficient rere minutes. Converting this charging method into carbon monoxide with formation enables the reducing gas to be recovered,
a cast iron containing not more than 3.5% chromium and a residual slag containing about 6% iron is selected so that it does not only hold the cast iron in the Furnace collects stoichiometrically.n ratios of the simplest re-formation corresponds to the formation of a permanent metal bath under induction reactions, according to which the given electrodes and under the liquid bath all the carbon present with the oxygen of the slag, the thickness of which corresponds to the size of the oxides, which are to be reduced, CO forms, order of 50 to 80 cm, and in which the 60 but also that a carburization or an up-end of the electrodes is possible at a depth of about 30 cm of the cast iron,
submerge from the surface of the slag bath. Due to the selection of the amount of carbon

According to a preferred embodiment of the containing reducing agent, the residue has

Verfahretis is a secondary peripheral feed slag with an iron content in the range of 6%, provided with a solid cooling charge, which exceeds 65 the chromium content of the cast iron 3 to 3.5%

a self-lining djj. «furnace favors and from not and is the carbon content of cast iron

an iron-rich slag, which by 3%.

enrich the pyrometallurgy of laterite- This selection is the result of a number of

21 from left

5 6

Investigations, and with the help of the investigations The refractory lining of the floor and the

results became the diagram of FIG. 2 drawn, furnace walls are made according to the invention by magnesia

which includes two curves denoted by I and Π stones. These stones are not affected by the cast iron

and that at the same time attacked the Cr or G content of the er ', and it was observed that the attack

held cast iron depending on the iron content 5 of these stones through the slag due to the self-

the slag shows. lining was stabilized and stopped and this

The mentioned cast iron, the chrome or carbon in spite of the low basicity of the slag

has a substance content of about 3%, is due to its /% CaÖ +% MgO Λ

Properties that are necessary for further metallurgical I - - > 0.5 y.

interesting work is an advantage. i « ^{v / o Μυ} * '

As the carbon content of cast iron is in the range the interior of the furnace is kept under a light

of 3%, its fluidity for the further hand pressure of a few millimeters of water column is around

habitations sufficient; continue to result in maintaining a reducing atmosphere,

a chromium content of the same order of magnitude The casting obtained at the outlet of the electric furnace

no difficulties at the moment of conversion, iron is subjected to desulfurization and in

and the steel obtained thus easily reaches a steel converted.

Chromium content below 0.5%. It has been found that the desulfurization is carried out by adding such a steel in an unexpectedly good ductility mixture of ferrosilicon and Na ₁ CO ₃ to the ablility properties, so that with conventional tapping troughs at the moment of tapping the cast iron; ways of turning how soft steel can be used. ao and other additions are made during the decanting process. The slag and the carbon dioxide are fed into a second tank and, at the moment when the reducing agent containing cast iron is put into the electric furnace, it is returned to the first tank. So dutch becomes a central opening. the sulfur content of the cast iron to a value of It is advantageous, at the same time, a peripheral level is lowered below 0.06%; It is therefore possible to provide a classic feed that uses a self-lining of the fuel containing fuel, which favors the furnace and for what purpose it is usually considered to be too sulphurous, possibly a cooled and coarsely ground one which is an advantage in economic terms. Slag is used, which comes from the enrichment treatment. The endothermic character and the velocity 30 It has been found that the chromium content of this casting of the reactions which take place in the furnace are of such a kind, iron under the conditions according to the invention, that the addition of the charge practically rend of the oxygen blowing the temperature of the slag was lowered to below 0.5%, while the iron yield caused it, which facilitated the control of the furnace3 and remained satisfactory, ie above 90%. the self-lining by the supplied slag 35 that protects the cast iron used to treat. Includes electric furnace, as shown in FIG. The electric furnace used, which is described in the following with a furnace frame 1 with a suspended ceiling 2 and a furnace length, is a furnace with a submerged sole 3 and three electrodes 4 which have an electric arc at the tips and an uncovered bath . of a simultaneous triangle are arranged, whose

In this electric furnace, the immersion depth is the 4 ° center of gravity in the furnace axis. Electrodes selected in such a way that the value of the elec- The magnesia bricks S, which are designed and arranged

tric power factor cos φ between 0.88 and 0.92 means that the furnace base has a concave shape

lies, which corresponds to an immersion depth of about 30 cm, forms three superimposed layers

where the cos φ at an electrical reduction and are from one layer to the other against each other

oven represents the following ratio: 45 staggered.

useful energy (kW) It is advantageous to use slots 7 and corresponding

, -. »_. . «« * Ν 'ribs or feathers 8 on each of the stones 5, as

entire eteklnsche energy (KVA) ^^ "kill and L two neighboring standing"

While with comparable electrical reductions, eat

tkmsöfen the value of cos φ is normally increased above the furnace base.

Is 0.95, the selection of cos φ selected here is from The three steroids rotated S «earths from two shifts

the need to carry the electrodes on a 10 made of magnesia bricks that are laid flat

Immersion depths that are at the same time small enough and that in turn, as shown in the drawing

is, so that the furnace sole is not attacked and through the masonry house Silidumdioxydataniniuin ·

on the other hand, it is very important to avoid carrying the 55 oxide stones,

electric current only through most of the How the stones S, which form the furnace floor, are di <

gnt conductive ScMcM flows, which is on the surface of the walls 12 of the furnace to the magnesia stone is below

Bath is formed by the reducing agent. This different shape, as shown in the drawing, on ge Layer that is thus in contact with the electrodes builds.

and their anes usually the honor tanch- 60 The stone lining formed in this way is in the interior

level of the electrodes would vrir, ii a furnace frame I arranged, with an intermediate

the wear and tear of the electrodes. layer 14 made of a conductive and relatively plastic "

In practice, the regulation of the immersion material is carried out as is arranged on the electrode mass

depth of the electrodes, on the cos φ on the desired and a water range system on the surface

th value to set trad am the calories in a gc- 6 $ of the oven rack, which is not shown, a cool down

gnawing depth to the re, continuous, and that of the latter ensures.

Immersion depth fluctuates on average at a value of The ceiling 2 is 15 mi from the highly refractory stones

about 30 cm below the surface of the slag. high almo content.

As in Fig. As shown in Figure 1, the furnace includes a bath comprising a cast iron layer 16, a slag layer 17 and a layer of slag a layer of carbonaceous reducing agent comprises, and the electrodes 4 are immersed in this bath, the extreme end of which is within the Scj> back layer is located.

Ali def place where the electrodes dunih the Enter ceiling 2, this is through lined jacket tube 19 (which are only shown for one of the electrodes) protected, and the electrodes are at their upper part by an electrically controlled mechanism 20 held, the details of which are not specified and which ensures the control, d. H. the extent of immersion of the electrodes in the slag layer 17.

The mechanism 20 as well as the devices for central loading and those for peripheral loading, which will be discussed later are supported by a schematically indicated frame 21.

The central loading devices comprise a loading chute 22 to which on the one hand with the aid of the devices 23 the carbon-containing reducing agent from a hopper 24 and on the other hand with the aid of the movable devices 25, as shown in the figure, the to be treated liquid slag can be introduced from a pan 26.

The charging shaft 22 is formed by a lined part, which is located in the furnace ceiling Loading opening protects, and this part is in turn protected against the occurrence of slag, with the help of another lined component 27 that is easily exchangeable and that of the slag introduction device 25 is carried, is fed.

A group of storage vessels or hoppers 28, which are arranged on the periphery of the furnace and which are supported by the frame mentioned, are used for peripheral charging with the help of iron tubes 29 which end above hoppers 29 a, which in turn led through the ceiling 2. The hopper 29 d include schematically drawn closure devices 29 b, with the help of which it is possible to reduce a

Maintain a decorative atmosphere inside the electric furnace, and the hopper 22 includes also locking devices 22a, which can sit on the flange 226. The self-lining, which is favored by the peripheral loading,

ίο is shown schematically at point 30.

It is advantageous to use the feed points of the peripheral Arrange the loading taking into account the position of the two tap holes and the three electrodes.

is Two tapping openings 31 and 32 are provided for tapping the cast iron or the slag. The tap holes 31 and 32 are, as shown in the figure, of known classical construction.
In a preferred embodiment

obtained such good results, with the help of the same oven, whose inner diameter 12 m and its inner height 4 m and the three Soederberg electrodes with one Had a diameter of 1.30 m, which at the tips of a simultaneous triangle with a side of

as 3.3 m were arranged and these electrodes a Output of 16,000 kVA.

The amount of cast iron contained in the furnace is about 300 tons and the thickness of the slag layer is SO up to 80 cm. The tap holes 31 and 32 are arranged with a height difference of about 50 cm, and an iron tap of 15 tons takes place every 2 hours.

The following example is intended to illustrate the method in accordance with the invention explain further on the basis of the furnace mentioned.

35

example

A quantity of 15 tons of a Schkcke, whose Iron content is 40.1% and its composition in percent is as follows:

FeO Fe ₁ O, CaO SiO ₁ Al ₁ O, Cr ₁ O ₁ MgO S. Ni 42.7 9.8 6.8 19.8 14.7 3.1 2.1 0.18 0.13

Is placed in an electric furnace (with the above specified at the level of the slag bath, ski, Characteristics) introduced after one has entered the gM- «$ a place, aa of which one has an outrageous self-ghen Furnace an amount of 2100 kg (140 kg per ton of lining aufreetsteröalten flraß, uffi the attack Slag) to fight coke with a grain size between 15 and through the slag. 30 mm has introduced and its composition The percentage composition of among these the following is: conditions formed cast iron is the following:

55

Solid volatile matter ash S

83.6% 4.3% "11.1% 0.7%"

The moisture content of the coke is about 6a

The composition of the remaining slag of the furnace, which cools coarsely comminuted slag, is introduced at the periphery during operation: which comes from the ferronickel wall and is long
Contains more than 60% iron The grain size of this e $
Slag lies below 50 mm. The addition takes place
intermittently and depending on the display of
Pyrometers around the furnace wall, in particular

409582/343

C. Cr Si Mn I P S. Ni Fe 3.2 34 0.2 OA j 0.07 0.40 0.40 92 ^ 3

Fe FeO CaO SiO, ΑΙ, Ο, CuO, MgO 6.5 8.4 14.5 39.8 29.5 2.1 4.1

At the exit of the furnace, the cast iron obtained in this way is tapped in warnings of 15 ΐΌηηβη and subjected to deisitifurierüiig. For this purpose, FeSi and sodium carbonate are added to the water while the tea is being wiped out, and this addition is done in such a way that it is finished when the water is filled. The added §M * ieiige questioned about 1% of Gußeisenmeftge while the Öösaflitmenge of added Na ₈ CO ₃ 1.5% A & T Öüßeisenmenge achieved The sodium carbonate 'nat is added in three step a:

1% during tapping into the furnace at the same time as the ferrosilicon,

1% during the transfer to a second tank, and

0.5% during the transfer of the contents of the second tub into the first tub.

Due to the performed in the manner described Desulfurization achieves sulfur contents of less than 0.06%.

The cast iron desulphurized in this way is converted in an 15-ton cooverter. That Oxygen bubbles up to a carbon * content of below 0.10% carried out. The iron yield is 92%, and the composition of the Steel after freshening results in percent as follows:

The composition after deoxidation, which takes place partly in the same converter, is the the following, expressed as a percentage:

5 C Si Mti P. S. Gf Fe 0.12 0.25 0.65 0.04 0.04 1.12 97.78

C. Si Mn P. S. Cr Fe 0.08 traces traces 0.04 0.04 0.53 99.3

The mechanical properties of the ίο steel thus obtained are:

Tensile strength (kg / mm ^a ) 47.1

Yield strength (kg / mm *) 34.1

Elongation,% 30

Constriction of fracture,% 53

At the exit of the converter, the steel obtained in this way is continuously tapped into a device, produces the strands with a cross-section of 80> 80 mm. The fluidity of the steel thus obtained is

ao sufficient to be able to cut off strands with such a small cross-section.

This steel is despite its relatively high chromium content soft and is z. B. suitable for the production of structural steel (reinforcing steel).

as As can be seen from the above, lets with the method according to the invention and the device used thereby using a classical and economical carbonaceous reducing agent in a simple manner heights cast iron Produce quality without the need for significant amounts of quick lime to form of calcium carbide to be supplied. Furthermore, it is him < according to the invention possible to achieve a self-lining of the electric furnace used, which is an

disturbed continuous operation possible

For this purpose 2 sheets of drawings

Claims (3)

treatment of nickel and cobalt, inside an electric reduction furnace, in the presence of a classic and economical 1. Process for the production of cast iron by redwkJionsroittels containing carbon. ....... Bandeln of chromium and iron-containing liquid 5 It is known that the production of nickel by Slags that lie from pyrometallurgy by late-pyrometallurgical treatments rite minerals originate in known ways and latent ores containing chromium in recent times Way for the extraction of nickel and cobalt has experienced a great boom. acts have been, inside an electrical Such treatments exist z. B. in the reduction furnace, in the presence of a classic to the applicant then carried out that and economical carbon-containing Reduk- man a selective partial reduction of the ore in rionmittel, characterized in a rotary kiln with the help of carbon-containing that the slag bath in the electrical reducing agents such as lignite or carbon, furnace in which passes through the central zone of the hollow, which leads to a product that is practically rough in the furnace, the liquid to be treated is made of metallic iron, but about 2% coal slag is introduced, apart from a lenstoff, one contains a weakly reducing melt-thin reducing agent layer is uncovered, zen of the product that is obtained from the rotary kiln, the reducing agent, which is free of flux, inside an electric furnace with immersion agents and additional products, is less than fc% tem Performs an electric arc, which results in a contains metal-volatile substances and has a grain size lower than 20 lish phase, which is half 50 mm due to a ferronickel alloy, with 80% of the particles being formed. After these treatments have a grain size above 0.15 mm, and adding large amounts of liquid slag, the reducing agent of which is progressively and separately iron content about 40%,
of the slag simultaneously and / or between it has already been proposed to add slag of this type to individual slag charging operations, 25 to treat the iron in the liquid state in order to extract the amount of reducing agent chosen by placing it inside an electric that it According to the stoichiometric proportions of the furnace with a reducing agent, which in certain cases satisfies the simplest reduction reactions, is finely divided, and with various solid denatures all the carbon supplied, which in certain cases of iron ore, is used to make the metal bath into a cast iron 30 stand, mixed, whereby the whole thing in certain cases with a content of about 3% carbon to carene forms a paste-like mass, which is then burnt and on the other hand is subjected to the oxygen of a part of the reduction,
of the metal oxides of the batch to a sufficient extent. The processes proposed so far suffer from converting pure carbon monoxide with the formation of known disadvantages. So go, if you are relatively a cast iron that does not contain more than 3.5% chromium 35 significant amounts of solid materials, such as flux, and a residual slag that adds about 6% iron or ores, these additives at the expense of the host, with The cast iron in the furnace is used for economic purposes. On the other hand, if the reducing agent is finely combined under the electrodes and under the liquid divided form, and the slag is collected discontinuously in the bath of the treated slag, the thickness of which in the liquid form adds in relatively considerable quantities, order of magnitude, with the formation of a permanent metal from 50 to 80 cm, and in what violent reactions between the reducing agent before the ends of the electrodes at a depth of and the iron oxides contained in the slag, which about 30 cm from the surface of the slag bath leads to violent gas outbreaks and thus losses and immersion . Leads to hazards. The chromium content is also there 2. The method according to claim 1, characterized in that a cast iron is drawn, starting from chrorc, that a secondary peripheral feed containing laterite has received, generally for one with a solid cooling charge provided for conversion into steel too high and for economical The fact that the furnace is self-lining favors its use as ferrochrome is too low. Further and consists of an iron-rich slag, which, due to the chromium content, leads to the cessation of the by enriching the 50 carbon content in pyrometallurgy to fluidity difficulties, and Alloys obtained laterite starting materials result in increased investment costs if received in the converter. ferrous slags are to be treated, which are from 3. Device for carrying out the process of metallurgy of nickel-containing latents come from, according to claims 1 and 2, characterized from US-PS 3,150,961 is a method for known by an electric reduction furnace from the reduction of metal oxides, in which one Type of immersion with an uncovered bath for the manufacture of the product avoided saturation with carbon of cast iron, the sole and walls of which are covered with one, around the subsequent decarburization refractories Magnesia lining are provided. to make steps more economical. This previously known Process can be seen on the manufacture of 60 low carbon iron alloys directed to in in this way to avoid further process steps for decarburization during further processing. at this previously known method is called the actual The invention relates to a method and a pre-reducing agent used calcium carbide, which in direction for the production of cast iron by Be 65 must be made in situ. For this it is necessary deal with chromium- and iron-containing liquid slag- first in the electric furnace lime with coal sink, to reduce the pyrometallurgy of laterite minerals to calcium carbide, which originate which in a known manner for the profit including the reduction of the mineral to be treated