JPH01252714A - Mixed agglomerating briquette for smelting reduction furnace and smelting reduction method for mixed agglomerating briquette - Google Patents

Abstract

PURPOSE:To stably produce molten pig in excellent productivity by semi-reducing crushed iron ore in fluidized bed reaction furnace with powder of the preheated lime stone by high temp. exhaust gas from a smelting reduction furnace, and then mixing it with coal, briquetting the mixture and charging it into the smelting reduction furnace. CONSTITUTION:The iron ore and lime stone are charged into the fluidized bed reaction furnace 2 after heating in a preheating furnace 1, and to the preheated iron ore under fluidized condition, lime, coal, oxygen-contained gas are injected, and the coal is thermal-decomposed and made to char. Further, CO-contained reducing gas 23 from the smelting reduction furnace 4 is injected into the fluidized bed reaction furnace 2 to semi-reduce the iron ore. This preheated semi-reduced iron ore, etc., is mixed with the coal 7 having 20% volatile matter and made to the briquette, in which distributes much coal in center and much pre-reduced iron ore at outside with a briquetting machine 3, and charged into the smelting reduction furnace 4 with charging device 8 and perfectly reduced to produce the molten pig. The reduction of the iron oxide in the iron ore is executed at good yield and slag foaming is a little and the molten pig is produce under stable furnace condition at good yield of the raw material ore.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mixed agglomerated briquette for use in a melting reduction furnace and a method for melting and reducing the same.

[Prior Art] For example, JP-A-61-64807 discloses a method in which briquettes obtained by mixing and agglomerating pre-reduced ore and char with coal are charged into a melting reduction furnace.

Figure 4 shows the flow.

That is, in the figure, iron ore and limestone are heated in an ore preheating furnace 1 by the heat of combustion reaction between coal and air.
It is supplied to the fluidized bed reactor 2.

In the fluidized bed reactor 2, coal and oxygen or oxygen-containing gas are blown into the preheated ore and quicklime in a fluidized state.

The injected coal is thermally decomposed through heat exchange with the preheated ore and partial combustion due to reaction with oxygen, generating reducing gas and turning into char.

In the melting reduction furnace 4, oxygen is blown toward the bath from the top blowing lance 5, and oxygen and carbonaceous material such as coal are blown into the bath from the bottom blowing tuyere 6.

Then, the carbon material 13 contained in the supplied briquettes 17
A large amount of heat is generated by the reaction between the carbonaceous material blown in together with oxygen from the bottom blowing tuyere 6 or the carbonaceous material such as coke supplied from the charging device 7 and the oxygen supplied from the top blowing lance 5. Occur.

The semi-reduced ore in the briquettes 17 is melted by this large amount of heat, and the reduction progresses to become molten iron 19.

In this example, the product of the preliminary reduction process in the fluidized bed reactor 2 is agglomerated, and this is preferentially melted and reacted at or near the interface between the molten iron 19 and the slag 20 in the smelting reduction furnace 4.

[Problem to be solved by the invention] When mixed agglomerates (briquettes, etc.) are charged into an iron bath, heat transfer and melting occurs from the outside, but due to the rise in temperature, coal decomposition gas is first generated, and then coal decomposition gas is generated. When heated, this gas reduces the ore. Since heat transfer takes longer in the center of the mixed agglomerate, there is a time lag between gas generation and the start of reduction, and the proportion of generated gas that is effectively used for reduction becomes smaller.

The present invention proposes an agglomerated briquette that protects refractories in an iron bath type smelting reduction furnace and improves productivity through steady operation, and its smelting and reducing properties.

[Means for Solving the Problems] The present invention provides a molten coal with a volatile content of 20% or more and an ore with a reduction rate of 60% or more. This is a mixed agglomerated briquette for reduction furnaces.

Furthermore, the present invention pre-reduces iron ore in a fluidized bed reactor to obtain semi-reduced ore with a reduction rate of 60% or more, and mixes this semi-reduced ore with coal having a volatile content of 20% or more supplied from another system. The agglomerated briquettes formed in multiple layers such that the ore ratio becomes higher in the outer layer are charged into an iron bath type smelting reduction furnace, and the semi-reduced ore is melted and reduced. This is a melt reduction method.

According to experiments conducted by the present inventors, by arranging more coal in the center of the mixed agglomerate and more ore in the outer periphery, coal decomposition gas can be efficiently used to reduce ore in the outer periphery where the temperature is higher. .

That is, as shown in Fig. 1, the briquette of the present invention uses coal powder having a volatile content of 20% or more as the inner layer core 1, and has a reduction rate of 60%.
% or less of partially reduced ore as the outer layer 2 (Fig. 1a).

An example of this is shown in Table 1.

Table 1 In addition, when layer 1 is a mixed layer with semi-reduced ore rich in coal having a volatile content of 2096 or more, the outer layer of layer 3 is rich in partially reduced ore. An example of this is shown in Table 2.

Table 2 Therefore, the inner layer and outer layer in the present invention also include ore and coal mixed in a predetermined ratio.

When the briquettes of the present invention are charged into an iron bath, a rise in temperature generates coal decomposition gas, and this gas reduces the ore. do.

According to experiments, the pre-reduced ore forming the outer layer of the briquettes preferably has a reduction rate of at least 60%.

Next, the method for melting and reducing agglomerated briquettes of the present invention will be explained. FIG. 3 shows the flow.

Iron ore and limestone are heated in an ore preheating furnace 1 and supplied to a fluidized bed reactor 2. In the fluidized bed reactor 2, quicklime, coal, and oxygen-containing gas are blown into the preheated ore in a fluidized state, and the blown coal exchanges heat with the preheated ore, thermally decomposes, and turns into char. In addition, the reducing gas 23 is blown into the fluidized bed reactor, and the ore is semi-reduced (6
0% or more).

The pre-reduced ore is agglomerated together with coal 7 to form briquettes having more coal 7 in the center layer and more pre-reduced ore in the outer layer. The briquettes are charged into the top-blowing converter type melting and reduction furnace 4 by the charging device 8 .

The temperature of the briquettes charged into the furnace increases due to heat transfer from the outer periphery, and when the temperature reaches 500 to 1000°C or higher, coal decomposition gas is generated, and when the temperature reaches 1000°C or higher, reduction reaction (I) and coal gasification reaction ( n) occurs, and the reaction occurs more actively as the temperature increases to ~1500°C.

In the center of the briquette, the start of reduction is delayed because it takes time to raise the temperature, but when the generated gas passes through the outer periphery where the temperature is higher, the reduction reaction progresses and the reduction is carried out efficiently.

FIG. 2 is a temperature chart when the briquettes shown in FIG. 1(b) are melted and reduced.

That is, according to the briquette of the present invention, reduction within the briquette progresses well before the briquette dissolves into slag.
Iron oxide concentration in slag decreases.

[Effect of the invention] Since the present invention uses a briquette with coal as the inner layer and semi-reduced ore as the outer layer, coal decomposition gas is generated, and as the temperature increases, the ore reduction reaction occurs, suppressing slag foaming and improving fire resistance. Damage to objects caused by FeO can be reduced. Alternatively, productivity can be increased by performing steady operation near the operational limit (T, Fe) due to forming.

[Brief explanation of the drawing]

Figures 1a and b are schematic diagrams of the example of the present invention, and Figure 2 is a diagram showing the temperature -
FIG. 3 is an explanatory diagram of the present invention, and FIG. 4 is an explanatory diagram of a comparative example. 2... Fluidized bed reactor 4... Melting reduction furnace 5.
... Oxygen lance agent Patent attorney Tatsuo Chanoki Procedural amendment (
(Voluntary) May 17, 1986

Claims (1)

[Scope of Claims] 1. A mixture for a smelting reduction furnace in which coal with a volatile content of 20% or more and ore with a reduction rate of 60% or more are mixed and formed into multiple layers such that the ore ratio increases in the outer layer. Agglomerated briquettes. 2. Preliminarily reduce iron ore in a fluidized bed reactor to obtain semi-reduced ore with a reduction rate of 60% or more, and mix this semi-reduced ore with coal with a volatile content of 20% or more supplied from another system. ,
A method for melting and reducing agglomerated briquettes, characterized in that agglomerated briquettes formed in multiple layers such that the ore ratio becomes higher in the outer layer are charged into an iron bath type melting and reducing furnace, and the semi-reduced ore is melted and reduced. .