EP0948656A1

EP0948656A1 - Method for downgrading high-melting materials by using a melting tank and an electro-reduction tank

Info

Publication number: EP0948656A1
Application number: EP97947002A
Authority: EP
Inventors: Heinz Stark; Heribert König; Heinz-Günter ZIMMER
Original assignee: Mannesmann AG
Current assignee: SMS Siemag AG
Priority date: 1996-10-10
Filing date: 1997-10-02
Publication date: 1999-10-13
Also published as: AU5221298A; WO1998015665A1; DE19643459A1

Abstract

The invention relates to a method for downgrading high-melting materials, specially ash from minerals containing metal or metal oxide, characterized by the following steps: a) high-melting materials are molted down in a first high-performing melting aggregate; b) a molten bath, excepting the start-up phase, which is separated according to its specific weight is deposited in a second metallurgical tank in an intermediate product area close to the ground consisting of metal, metal mattings as well as metal stones and an area of ash swimming on top thereof; c) at least the molten liquid conglomerate is fed from the first tank to the second metallurgical tank whereby the added volume makes up 15 to 25 % of the molten bath volume deposited in the second metallurgical tank; d) the molten bath deposited in the second tank is charged with electric heat energy via electrodes whereby the electrodes are dipped in the molten bath and the spacing between the electrodes and the dipping depth of the electrodes in the molten bath is measured in such a way that 65 to 70 % of the energy charge takes place between the electrodes and the product bath, and e) subsequently partial amounts of the ashes as well as the of the intermediate product are subjected to discontinued run-offs.

Description

METHOD FOR DEPELLING HIGH-MELTING MATERIALS USING A MELTING VESSEL AND AN ELECTRO-REDUCING VESSEL

description

The invention relates to a method for depleting high-melting materials, in particular slags of minerals containing metal and / or metal oxides.

The usual procedure for the removal of slag, slag mat mixtures and slag stone mixtures as well as for the melting and depletion of return materials, in particular from the steel mill converter, is as follows:

There is a metal or metal mat or metal stone bath layer protecting the infeed in the electric furnace. On this intermediate product layer there is a slag bath layer, the height of which is kept to a minimum but is selected so that a resistance system is formed by the maximum heat required for the process sequence being able to be converted. In this process it comes to high electrical inductive and ohm ^'chen losses as resulting from the low Schlackenbadhöhe slag resistances are small and require a current-intensive performance image.

The method has set itself the goal of achieving a higher level of separation of the metal to be extracted from the gaits using simple means and using energy sparingly.

The invention achieves this aim by the characterizing features of the method claim 1. Advantageous developments of the inventions are set out in the subclaims. According to the invention, the first high-performance melting unit is followed by a second metallurgical vessel. This second metallurgical vessel is an oven vessel which is electrically heated in at least two electrodes. In the area of the hearth of this metallurgical vessel there is an intermediate product made of metal and / or metal mat and / or metal stone melt. On this

An intermediate product is a slag bath layer.

The batching in this second metallurgical vessel looks as follows:

- From the first high-performance melting unit, for example, 10 to 25% Cu ₂ 0 + Cu ₂ S are charged at a temperature of 1200 to 1250 ° C.

Slag from a steel converter can also be added.

30 to 35% Cu ₂ 0 + Cu ₂ S from return materials and

Coke for the reduction of oxidically or sulfidically bound metal and for the creation of a reducing atmosphere above the melt.

Increasing the temperature increases the viscosity of the melt. As a result, heavy metal and / or metal mat and / or metal stone particles can settle on the hearth as an intermediate product.

The longest possible amount of slag is collected in the second metallurgical vessel. For this purpose, the metallurgical vessel is charged to such an extent that there is approximately 6 times the bath volume of the volume which is charged per hour. Due to the high bath volume, the longest possible residence time, ie settling and leaching time of the melt. The degree of depletion of the melt reaches its maximum. Due to the large volume of slag, the output can be made more resistance-sensitive, ie with lower current and therefore with lower electrical losses. The electrical energy is supplied to the electric furnace by means of carbon electrodes which are immersed in the melt. The heating mechanism is the current flow through the resistance of the slag between the electrodes and the

Resistance between the electrodes and the metal accumulating on the stove floor.

Due to the temperature difference between the charged materials and the molten slag in the furnace and due to the different specific weight between the charged and the furnace due to the different metal content, the new charged material falls into the lower layers of the existing slag on the product bath. The material extracts heat from the product bath and absorbs heat from the slag.

The depleted slag rises to the upper layers of the bath to the extent that the charged material absorbs heat to raise the temperature as well as to react and melt heat, reactions occur and metal fails. It can be seen that a sufficiently depleted final slag is found especially in the uppermost layers of the melt pool.

In the proposed method, a high proportion of energy is introduced into the lower volume area of the molten bath, since the reaction of the process is started there. If necessary, there will be another one before tapping

Dwell time inserted without batching to deposit product particles.

After depletion and reduction of the slag, the so-called final slag, i.e. the slag with the highest degree of depletion, tapped. The slag tapping volume is approx. 20% of that in the furnace

Total slag volume. The tapping takes place at a level which ensures that after the tapping, the reclosable tap hole is still 150 to 200 mm below the total bath level. The intermediate product precipitated near the bottom is also tapped discontinuously, on a level that is between 40 to 60% of the level of the entire intermediate product.

The intermediate product is used for further treatment, in particular for cleaning

Converters fed.

After tapping the depleted final slag and the intermediate product, a new batch is fed into the metallurgical vessel. The slag is again heated from about 1200 to 1250 ° C to a temperature of 1300 to 1400 ° C. The distance between the electrodes used and the depth of immersion of the electrodes in the melt is such that 65 to 70% of the energy input takes place between the electrodes and the product bath. This electrical heating is carried out for the purpose of maintaining the temperature and increasing the temperature, and for supplying the heat required for the reactions to occur and for the purpose of increasing the viscosity. The heating mechanism is the current flow through the electrical resistors that form the slag between and under the electrodes.

Since the process is carried out with largely constant bath conditions, there is an equalization of the electrical conditions and thus an equalization of the power consumption.

An example of the invention is set out in the accompanying drawing. The shows

Figure 1 is a flow diagram of the overall process and

Figure 2 schematically shows the heating mechanism.

FIG. 1 has a high-performance melting vessel 11 which has an oven bottom 14 and an oven wall 15.

An opening 17 is provided in the furnace bottom 14, through which metal 12 is tapped, which is fed to a converter 51. An opening 18 is provided in the furnace wall 15, through which slag 13 is tapped, which is fed to the second metallurgical vessel 21.

The metal 61 located in the converter 51 is charged into the high-performance melting vessel 11. The converter slag 62 is fed to the second metallurgical vessel 21 together with the tapping slag 13, with return material and with reducing agents. The return material is channel and pan outbreaks as well as residues from crushing processes and the like, which are fed as solid material to the electrically heated second vessel as solid material.

The second vessel 21 has a furnace bottom 24, a furnace wall 25 and a lid 29 placed thereon.

The operating states I, II and III are shown schematically in FIG.

In operating state I there is a metallic melt in the vessel near the furnace bottom. This metallic melt is always maintained as a sump with the exception of the first start-up phase. This metallic melt is an intermediate product consisting of metal, metal mat and metal stone.

There is a slag 43 on the intermediate product, in which liquid and solid materials are charged.

In the following operating state II, there is a metallic increase 42 on the metallic melt 41.

Above this intermediate 41, 42 there is slag 43 with the slag increment 44.

At the end of the production process, the slag 43, 44 is depleted in such a way that the uppermost slag layer 45 is without valuable material. In operating state III, the depleted slag 45 is tapped through a tap opening 23 to such an extent that the residual bath level is still approximately 150 to 200 mm above it.

Finally, the intermediate product 41, 42 is tapped at a height h _M , which is approximately half of the total metallic level H _n .

The metallic melt 28 tapped through the tap opening 22 is fed to the converter 51.

The electrodes 26 projecting into the vessel 21 through the cover 29 are shown schematically in FIG.

The electrodes are immersed in the melt and the distance between the electrodes and the depth of immersion of the electrodes in the melt are such that 65 to 70% of the energy input takes place between the electrodes and the product bath.

FIG. 2 shows the electrically heated second vessel 21 with the furnace wall 25, the furnace floor 24 and the lid 29. This is located near the furnace floor 24

Intermediate 41, 42 and then the slag 43 with the depleted slag 45 in the vicinity of the level of the total melt H _B a_-

The electrodes 26 are arranged with respect to one another so that on the one hand there is a slag volume V _{h of} the horizontal current flow and energy input and on the other hand there is one slag volume V _{v of} the vertical current flow and energy input per electrode.

Position list

First vessel

11 high-performance melting vessel 12 tapping metal

13 tapping slag

14 furnace bottom

15 furnace wall

17 opening metal 18 opening slag

Second vessel

21 Electrically heated second vessel

22 Tap hole metal

23 Slag tap opening

24 oven bottom

25 furnace wall

26 electrode

27 Depleted slag

28 metal mat

29 cover

Melt the first vessel

31 Metallic melt

32 slag

Melt the second vessel

41 Metallic melt, intermediate

42 Metallic growth, intermediate 43 slag

44 slag growth

45 depleted slag Converter system

51 converter

Converter melt 61 converter metal

62 Slag converter

h _M height tapping metal h _s height tapping slag H _M level metal

H _ß a _d level total melt

V _h slag volume of horizontal current flow and energy input

V _v slag volume of vertical current flow and energy input

I, II, III operating states

Claims

claims

1. A process for the depletion of high-melting materials, in particular slags of minerals containing metal and / or metal oxides, characterized by the following steps:

a) high-melting materials are melted in a first high-performance melting unit

b) is in a second metallurgical vessel, with the exception of the

Start-up phase, a melt that is separated according to its specific weight into an intermediate product zone near the ground, consisting of metal, metal mat and metal stone, and a slag zone floating on it

c) at least the molten mixture from the first vessel is fed to the second metallurgical vessel, the volume charged being 15 to 25% of the melt volume located in the second metallurgical vessel

d) the melt located in the second vessel is supplied with electrical thermal energy by means of electrodes, the electrodes being immersed in the melt and the distance between the electrodes and the depth of immersion of the electrodes in the melt being such that 65 to 70% of the energy input between the electrodes and the

Product bath takes place, and

e) Subsequently, portions of the slag and the intermediate are discontinuously tapped.

2. The method according to claim 1, characterized in that the residence time of the added material in the second vessel is chosen so that the product particles with a higher specific weight settle towards the bottom of the vessel, so that the top slag layer is without valuable material.

3. The method according to claim 2, characterized in that there is 5-7 times the bath volume in the second metallurgical vessel, which is charged per hour.

4. The method according to any one of the preceding claims, characterized in that a quantity of heat is supplied to the melt in a predetermined duration and amount, which allows a comprehensive reaction for depletion.

5. The method according to claim 4, characterized in that the slag is tapped in a tapping plane at a height hs corresponding to h _s = 0.7 to 0.9 x H _bath with H _bath as the overall level of the melt pool.

6. The method according to any one of the preceding claims, characterized in that the intermediate product precipitated near the bottom of the vessel is tapped in a plane which has a height h _M corresponding to h _M = 0.4 to 0.6 x H _M with HM as the level height of the liquid intermediate product.