KR830000063B1 - Sponge Iron Steel Making Method - Google Patents

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Description

Sponge Iron Steel Making Method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steelmaking method for directly reducing iron oxide containing material and melting sponge iron by an electro slag resistance method.

Residues from metallurgy, such as furnace dusts, ash from the Linz-Donaviz process and muds from the Linz-Donaviz process, contain significant amounts of nonferrous metals or compounds thereof It cannot be reloaded into the furnace or used for steelmaking unless their non-ferrous metal content is almost eliminated. The nonferrous metals and their compounds can be removed from the rotary furnace by reduction treatment with a solid carbon reducing agent. As a result of such treatment, the volatile nonferrous metals or their compounds can be removed from the rotary furnace with their exhaust gas and then separated from the exhaust gas and recovered. Iron oxide is reduced to sponge iron and contained in the solid material discharged from the rotary furnace. Non-ferrous metals of residues always contain Zn or a compound thereof, and the high volatilization of such Zn and the metallization of almost all iron oxides depends on the excess solid carbonaceous material of the furnace, and the replacement material discharged from the furnace contains excess carbon do.

It is known to use the electric slag resistance method to melt sponge iron and transform it into steel (“Stahl und Eisen” 97 (1977), 12-17). Sponge iron to be treated by the known method is produced by a reduction method using gas as a reducing agent rather than a solid carbonaceous material. Sponge iron with high content of surplus carbon, such as obtained by the Waelz method or direct reduction carried out in a rotary furnace by a solid carbonaceous reducing agent, contains more carbon than the final reduction is required and the hepatic content is greater. It does not charge because it changes. The surplus carbon can be separated from the sponge iron by sieving and magnetic flux separation, separated from coal ash by flotation or electrostatic separation and recycled to the rotary furnace so that the residue is too fine to be used in the process. Coal ash becomes useful when it is absent. The coal ash also contains a certain amount of carbon and iron.

It is an object of the present invention to provide an economical solution for sponge iron containing materials discharged from a direct reduction or belts process in which metallurgical residues containing iron oxides and volatile nonferrous metals or compounds thereof are carried out in rotary furnaces treated with solid carbonaceous reducing agents. To provide a simple process.

This object is achieved according to the present invention as follows. In other words,

(1) Metallurgical residues containing oxides and volatile nonferrous metals or compounds thereof are treated in a rotary furnace with a solid carbonaceous reducing agent and thus reduced to sponge iron at a high rate and a significant portion of those nonferrous metals are volatilized.

(2) The solid material discharged from the rotary furnace is separated into a sieve having a lattice size of about 3-10 mm depending on the particle size and decomposition characteristics of the residual material, so that most of the nonmagnetic material is contained in the fine debris.

(3) Coarse debris is processed by the electric slag resistance method.

(4) The micro debris is processed by electron separation.

(5) Magnetic debris is subjected to the electric slag resistance method.

(6) Nonmagnetic debris is bonded to the feed mixture of the rotary furnace by rolling or pelletizing operations.

In one embodiment of the invention, the non-magnetic debris is comminuted before being bound to the feed mixture. This grinding operation is adopted when it is not possible to combine almost all non-magnetic debris into the feed mixture. In a preferred embodiment, the sieving step 2 is carried out at elevated temperature and the fine debris is cooled to a temperature below 750 ° C. before the separation step 4. This reduces the cost of cooling and allows some of the heat contained in the feed of the electric slag resistance method to be used.

According to another preferred embodiment, step (2) is carried out to comprise at least 80% of the nonmagnetic material of the microdebris. This process gives good results for the whole process.

The advantage according to the present invention is that the material discharged from the rotary furnace is technically and economically simple, and undergoes special treatment to treat the material by the electric slag resistance method so that no residual material is additionally formed. By combining non-magnetic debris, consisting mainly of surplus carbon and coal ash, to the feed mixture of the rotary furnace, the carbon loaded in the rotary furnace is fully used in the rotary furnace and is fed to a feed containing relatively large amounts of solid carbon with low reactivity. Is introduced. The presence of carbon results in a high rate of volatilization of the nonferrous metal or compound thereof.

[Example]

The rotary furnace is 12m long, 0,8m long and is filled with green pellets and solid carbon reducing agents. Green pellets are produced from mixtures from furnace residues (A), LD residues (B), LD materials (C), mill residues D), and mixtures of residues in sinter plants and casting compartments (E). It has the same composition.

Solid carbon reducing agents have the following properties.

Example 1

Green pellets have the following composition.

53.1% Fe 1.8% Pb

3.3% C 0.3% S

3.0% Zn basicity 3.0, humidity 11.8%

The reducing agent consists of coke crumbs and briquette-shaped lignite and is charged to the rotary furnace with a C _fix of 1: 4 ratio. The pellets are charged into the kiln at 350 kg per hour and the ratio of C _fix and Fe at the end of the kiln loading is 0.60 and 0.20 at the discharge.

Solid emissions are sieved through a 3 mm sieve and coarse debris is 145.5 kg / h and is supplied by the electric slag resistance method. The composition of the coarse fragments is as follows.

75.8% Fe 1.22% Pb

1.2% C Metallization 94.4%

0.035% Zn nonmagnetic portion 3㎏

Fine debris is 82.5 kg / h and is fed to an electronic separator. The magnetic debris is 47.5 kg / h and is transferred by the electric slag resistance method. This composition is almost the same as for coarse fragments. The nonmagnetic fragments were 35 kg / h and contained 77% C _fix .

12 kg / h of oxide containing 35% Zn and Pb can be separated from the off-gas.

Example 2

In Example 1 non-magnetic fragments having a particle size of 3 mm or less were recycled to the mixture and mixed into green pellets before pelletizing. The pellet is charged at 385 kg per hour (11.5% humidity, C _fix 11%, Fe 48%). The ratio of Cfix and Fe at the end of the charging of the furnace is maintained at 0.6 by reducing the amount of new coal charged. The ratio of non-exhaust substances is 0.15.

Coarse fragments larger than 3 mm are 132.6 kg / h free of nonmagnetic materials.

71.5% Fe 0.31% Pb

1.8% C Metallization 97.1%

0.015% Zn

Fine debris is 84.4㎏ / h, and after electron separation, magnetic debris is 62.4㎏ / h and its composition is almost the same as coarse debris. The nonmagnetic fragments are 22 kg / h and contain 75% C _fix .

In practice, recycling the nonmagnetic micromaterials into the feed mixture may be adjusted to achieve a balance between the nonmagnetic micromaterials obtained and the recycled micromaterials.

Example 3

According to Example 1 the green pellet is fed by 300 kg / h and the reducing material is bituminous coal with a particle size of 1-10 mm. This does not decompose significantly, whereas the coals in Examples 1 and 2 decompose in a rotary furnace. At the end of charging, the ratio of C _fix and Fe is 0.60. The solid discharge is filtered with 10 mm sieve, coarse debris is 78.9 kg / h and the composition is as follows.

74.9% Fe 0.48% Pb

1.4% C Metallization 89.5%

0.043% Zn nonmagnetic portion 2.1㎏

The fine fragments are 123.2 kg and the magnetic fragments after the electron separation are 82.2 kg / h and have almost the same composition as the coarse fragments. Bazaar shards are 40 kg / h and contain 71% C _fix .

Example 4

In Example 3 35 kg / h of nonmagnetic fragments of 10 mm or less were crushed and recycled to the mixture before being pelletized and mixed into pellets. At the charging end of the rotary furnace, the ratio of Cfix and Fe is charged and kept at 0.60 by reducing the amount of new coal. Coarse fragments larger than 10 mm are 94.11 kg / h, and their composition is as follows.

71.0% Fe 0.19% Pb

2.0% C Metallization 93.8%

0.025% Zn nonmagnetic fraction 0.61㎏

The micro debris is 106.5 kg / h, and after electron separation, the magnetic debris is 76.5 kg / h and has almost the same composition as the coarse fragment. The nonmagnetic fragments are 30 kg / h and contain 73% Cfix. In practice the recycling of the non-magnetic micromaterials into the feed mixture is controlled to achieve a balance between the non-magnetic micromaterials obtained and the recycled micromaterials. As in Examples 1 and 2, coals having low particle size so as to obtain nonmagnetic materials from nonmagnetic fine debris can be obtained from coal having strong decomposing properties. It can be seen that the particle size is higher so that it can be obtained.

The green pellets were 10-20 mm in size and less than 50% degraded below 10 mm. Therefore, in Examples 3 and 4 it is possible to choose the size of 10 mm. If the pellets have strong decomposition properties, the sizes are reduced and smaller particle size coal is used in Examples 3 and 4. The volatility of lead and zinc is increased by recycling of nonmagnetic micromaterials.

Claims (1)

In the steelmaking method of directly reducing a substance containing iron oxide and melting sponge iron by electric slag resistance method, a metallurgical residual material containing an oxide and a volatile nonferrous metal or a compound thereof is treated in a rotary furnace by a solid carbonaceous reducing agent, Thus, at a high rate, it is reduced to sponge iron and a substantial portion of its nonferrous metal is volatilized; The solid material discharged from the rotary furnace is separated into a sieve having a lattice size of about 3-10 mm according to the particle size and decomposition characteristics of the residual material so that most of the nonmagnetic material is included in the fine debris. Under the treatment of slag resistance; Fine debris is subjected to electron separation; Magnetic debris is treated by an electric slag resistance method; A non-steel fragment is bonded to the feed mixture of the rotary furnace by rolling or pelletizing operations.