JPS62247014A - Carburization melting smelting method - Google Patents

Abstract

PURPOSE:To increase the rate of secondary combustion of a solid carbonaceous material by changing the amounts of the carbonaceous material and an oxidizing gas fed so as to specifically regulate the area of a fire spot and the amount of a suspended carbonaceous material. CONSTITUTION:A solid carbonaceous material suspended in slag in a reactor is burned by blowing O2 or a gas contg. O2 to generate heat and a bath in a reactor is agitated by blowing a gas from the bottom. Thus, a metal or a metallic oxide is melted and reduced. In this carburizing, melting and refining process, the oxidizing gas is blown from the top so as to regulate the area of a fire spot to >=30% of the area of the bath and the amounts of the solid carbonaceous material and/or the oxidizing gas fed are changed so as to regulate the amount of the solid carbonaceous material suspended in the slag to 5-20wt% of the amount of the slag.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a processing method in which solid carbonaceous materials are burned with a high calorific value to be used as a heat source and reducing agent when melting and smelting metals or metal oxides. Regarding charcoal melting and smelting method.

[Conventional technology]

In oxidation and smelting of hot metal, the carbon contained in the hot metal is efficiently combusted, thereby improving the thermal efficiency of the reaction system and increasing the amount of scrap charged. It is disclosed in Japanese Patent No. 8085.

In the method described in Japanese Patent Publication No. 56-8085, supplied oxygen and converter waste gas are mixed by supplying an oxygen flow that acts as a free jet in the converter gas chamber. The gas stream reaching the surface has a composition consisting of CO and Cot with almost no free oxygen. As a result, secondary combustion is actively performed, increasing the amount of heat generated. In this way, when increasing the amount of heat generation, the amount of solid iron material such as scrap can be increased accordingly.

[Problem that the invention seeks to solve]

However, in the method described in Japanese Patent Publication No. 56-8085, solid carbon suspended in a slag bath is not burned. Furthermore, it does not supply oxygen to the entire surface of the bath. For this purpose, (Co□1820)
/ The secondary combustion rate expressed as (Co + Co□+H2+H20) is 30 to 40% or less, and the combustion efficiency is poor.

Therefore, the present invention aims at melting and reducing metals such as scrap and metal oxides such as iron ore by burning solid carbon material used as a heat source and reducing agent at a high secondary combustion rate. The purpose is to accelerate the smelting reaction.

[Means for solving problems]

In order to achieve the purpose, the carburization melting and smelting method of the present invention sprays oxygen or oxygen-containing gas into the slag in the reaction vessel! The solid carbon material heated to tA'fra is burned to generate heat, and the metal or metal oxide is dissolved while stirring the bath by blowing gas from below the bath surface.

In the carburizing and smelting process for reduction, oxygen or an oxygen-containing gas is blown from above so that the flash point area is 30% or more of the bath area, and solid carbonaceous slag is suspended in the slag. It is characterized by changing the supply amount of either or both of the solid carbonaceous material and the oxidizing gas so that the weight ratio to the solid carbonaceous gas is within the range of 5 to 20%.

[Effect]

Raw materials such as metals and metal oxides charged into a reaction vessel are melted (?8 melting) using solid carbon as a heat source and reducing agent.
In the reduction process, the basic conditions for rapid melting and smelting reactions are to expand the reaction sites by vigorously stirring the bath, and to increase the secondary combustion rate of carbonaceous material. Become.

The reaction vessel used here includes one equipped with a top blowing lance for blowing oxygen or oxygen-containing gas onto the bath surface and a bottom blowing tuyere for blowing gas from below the bath surface. In this reaction vessel, oxygen or oxygen-containing gas from a top blowing lance is blown onto the solid carbonaceous material suspended in the slag bath,
At the same time as this is combusted, the metal slag bath in the reaction vessel is strongly stirred by oxygen-containing gas, inert gas such as Ar, or a mixed gas thereof blown from the bottom blowing tuyere. As the reaction process proceeds in this manner, the amount of heat generated by combustion of the solid carbonaceous material is as follows.

C+ '40 g-= CO+2200 Kcal/k
g −CC+Ot =C0t+7830 Kcal/
As is clear from the combustion reaction equation for CO2, it is important to burn solid carbon to CO2 in order to utilize heat efficiently.

Further, the carbon suspended in the slag bath is combusted through the following process.

First process C(solid) + Oz-= COHSecond process C(golid) + COx" 2 COHere, when solid carbonaceous material exists in excess in the slag bath in the reaction vessel, the second process As the combustion progresses, the secondary combustion rate R (Go) decreases as shown in FIG.

Furthermore, if the amount of solid carbon in the slag bath in the reaction vessel is extremely small, the slag will be in a state of excess oxygen and will cause foaming, interfering with stable operation.

For this reason, according to the results of the research conducted by the present inventors, maintaining the solid carbon suspended in the slag bath in the reaction vessel at a weight ratio of 5 to 20% to the slag is effective in increasing secondary combustion. This is one of the factors that enables stable operation at a ratio R(Co□). FIG. 1 shows the influence of the amount of solid carbon on the secondary combustion rate R (Co□).

On the other hand, when the oxygen jet from the top blowing lance collides with the molten metal in the reaction vessel, the following reaction occurs and CO is likely to be generated.

W Mouse+C-4c.

% Oz + X M = M +i 0MX0+C-
C0+XM In other words, in order to proceed with the reaction at a high secondary combustion rate, when dissolving or reducing metal oxides, etc., the metal bath in the reaction vessel is covered with slag to avoid direct collision of the oxygen jet with the metal bath. This is necessary.

By the way, in a carburizing and melting furnace, it is necessary to perform high-speed combustion in a small furnace body, so the oxygen supply rate is kept at 1000 to 200 ONrrr-0□/rrr (bath area) hr or more. There is. If such an amount of oxygen were to be supplied using a single top-blowing lance, acid would be blown at high pressure. As a result, the fire spot area is narrowed to 10-20% of the bath surface area, and the oxygen jet penetrates the slag bath and reaches the metal bath, where a reaction occurs. The penetration of this oxygen jet promotes the above-mentioned CO production reaction.

Therefore, one of the conditions required to increase the secondary combustion rate of solid carbon is to prevent the oxygen jet from the top blowing lance from penetrating the slag bath and coming into direct contact with the metal bath. It is one. This requires the presence of a molten slag layer of sufficient thickness.

However, the ratio of slag to metal is determined by the raw material conditions in the target melting and smelting method. For example, in an iron smelting reduction process, the slag/metal ratio is 200-300 kir/ton, and in a scrap melting process, it is less than 100 kg/ton. For this reason, the thickness of the slag layer may not be sufficient to prevent the oxygen jet from the top blowing lance from penetrating the slag bath and directly contacting the metal bath. Even in this case, it is necessary to prevent the oxygen jet from the top blowing lance from reaching the metal bath in order to suppress the CO production reaction.

For this reason, as a specific means in the present invention, there is a method of dispersing the oxygen jet from the top blowing lance as much as possible and spraying it evenly over the entire surface of the bath in the reaction vessel.

According to the research of the inventors, in order to prevent the oxygen jet from the top blowing lance from reaching the metal bath under normal oxygen loading, and to effectively burn the carbonaceous material suspended in the slag. found that it is necessary to make the flash spot area at least 30% of the bath surface area. The fire point area is 30
%, the kinetic energy of the oxygen jet becomes so large that it blows through the slag layer and reaches the metal bath. Such blow-through can be prevented by adjusting the flash point area as described above.

This enlargement of the fire spot area is achieved, for example, by concentrically distributing a plurality of top blow lances. It is also effective to make each lance a multi-hole nozzle.

At that time, the way oxygen is blown from the top blowing lance, the way the lance is divided, etc. differ depending on the shape of the furnace.

For example, when the cross-sectional shape of the reaction container is circular, it is preferable to arrange three to four lances concentrically.

This creates multiple flash points on the bath surface. In this case, each lance can be made into a multi-hole nozzle.
This is more preferable for further dispersing the flash point.

Additionally, if the cross-sectional shape of the reaction vessel is rectangular, it is best to arrange the top blowing lances in a staggered manner along the length of the reaction vessel. It is formed. In this case as well, it is preferable that each lance be a multi-hole nozzle.

〔Example〕

Three top blowing lances were arranged axially symmetrically at an inclination angle of about 60 degrees from the upper side wall of a reactor lined with a refractory having an inner diameter of about 1.2 m to blow acid. Approximately 6 tons of hot metal was initially charged into the furnace, and the hot metal was stirred by blowing oxygen and cooling gas through three bottom blowholes.

Carbon-containing iron ore briquettes were supplied from above to the hot metal in such a stirring state at a rate of about 20 kg/min to continuously perform melt reduction. Further, in order to ensure a predetermined slag thickness, auxiliary materials were added as necessary. The three top-blowing lances used at this time each had three eccentric nozzle holes at their tips. Then, the above 3.
The top-blown lance of the book was placed.

The back pressure of the oxygen ejected from these top blowing lances is approximately 6k.
g/-·G, but the height of the lance is adjusted so that the jet penetration load does not penetrate the slag layer. By using this method of blowing acid, CO! /C○ ratio was 40/60 or more, the calorific value of secondary combustion was large, and it became clear that more than 70% of the combustion heat of the furnace was effectively utilized.

On the other hand, the amount of additionally added solid carbon material such as coal briquettes was adjusted so that the ratio of carbon in the slag to the weight of the slag was in the range of 5 to 20%. The weight ratio of carbon in slag is determined by the amount of blown acid and COz/C in exhaust gas.
It can be accurately estimated from the o ratio and the amount of carbon input using the relationship of material balance.

By adopting this operating method, it was possible to melt and reduce a large amount of iron ore in a relatively small furnace with extremely high thermal efficiency. The operation was carried out under very stable conditions, with no slag forming.

〔Effect of the invention〕

As explained above, in the present invention, metals or metal oxides can be melted and smelted at a high secondary combustion rate by adjusting the fire point and the amount of suspended carbonaceous material.

That is, it is possible to manufacture metal using inexpensive primary energy such as coke powder without using electricity as a heat source, so the industrial effect is great. The method of the present invention is also highly efficient and extremely useful when melting iron-based metal raw materials such as scrap iron and reduced iron.

[Brief explanation of drawings]

FIG. 1 shows the relationship between the weight ratio of the solid carbonaceous substance suspended in the slag bath in the reaction vessel to the slag and the secondary combustion rate of the solid carbonaceous substance.

Claims (1)

[Claims] 1. Burning solid carbon suspended in slag in a reaction vessel to generate heat by blowing oxygen or oxygen-containing gas, and stirring the bath by blowing gas from below the bath surface. In the carburization melting and smelting process, which melts and reduces metals or metal oxides, oxygen or an oxygen-containing gas is blown from above and into the slag so that the flash point area is at least 30% of the bath area. A processing method characterized by changing the supply amount of either or both of the solid carbonaceous material and the oxidizing gas so that the weight ratio of the suspended solid carbonaceous material to the slag is within the range of 5 to 20%. Charcoal melting and smelting method.