JPH05171237A - Metal refining method - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a metal refining method capable of stably achieving a high secondary combustion rate and effectively recovering the secondary combustion heat without wearing out the equipment. [Structure] A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into the molten metal 3, and only the surface portion of the O ₂ gas in the molten metal 3 reacts with carbon in the carbon-containing fuel to produce CO. As a gas, this CO gas is blown into the furnace with a large diameter of bubble-like oxygen G ₁ from the bottom blowing tuyere 4 so that secondary combustion is performed in the slag bath 7 by the unburned O ₂ gas inside. reducing the flow rate of径気foam oxygen G ₁ in the furnace top or the furnace exit gas _{(CO 2 / (CO + CO} 2)) is reduced, increasing the flow rate of the large径気foam oxygen G ₁ in the opposite furnace (CO ₂ / (CO + CO ₂ )) of the upper part or the furnace outlet gas is used to control the flow rate of the large-diameter bubble-like oxygen G ₁ to control the (CO ₂ of the upper furnace part or the furnace outlet gas). / (C
O + CO ₂ )) is adjustable and is a metal refining method.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting and refining a metal raw material by introducing a metal raw material, a carbon-containing fuel, a slag forming agent and O ₂ gas into a metal melt.

[0002]

BACKGROUND OF THE INVENTION The present invention applies to the following two refining processes. That is, the first is the smelting reduction method. The smelting reduction method is an alternative to the blast furnace method.The blast furnace method requires a large number of auxiliary equipment, requires expensive raw materials such as strong coking coal, and it is difficult to significantly change the production amount. Since it has the drawback of being expensive and requiring a vast site, it has been developed in recent years as a technology without these drawbacks.

A general smelting reduction process has a smelting reduction furnace and a preheating / pre-reduction fluidized bed furnace as main equipment. The smelting reduction process is summarized as follows. Pre-heating / pre-reduction The metal oxide, which is a metal raw material, is pre-heated in the fluidized bed furnace by the exhaust gas from the smelting reduction furnace
After the preliminary reduction, it is charged into a smelting reduction furnace together with a carbon-containing fuel such as coal and a slag-forming agent. This smelting reduction furnace has O ₂
O ₂ gas (hereinafter referred to as “main O ₂ gas”) in which the gas and the stirring gas are blown, and the carbon-containing fuel is dissolved in the metal melt already generated in the smelting reduction furnace and carbon in the carbon-containing fuel is blown. It is referred to as ".") And burns to CO gas by oxygen remaining in the ore, and at the same time, heat is generated. The combustion heat melts the metal raw material, and the metal raw material is finally reduced by carbon. Then, a part of the CO gas is secondarily burned to CO ₂ gas by O ₂ gas blown from a system different from the main O ₂ gas (hereinafter referred to as “O ₂ gas for secondary combustion”), The heat generated at this time is also recovered in the molten metal to be used for the dissolution of the metal raw material and the final reduction reaction.

The second is a metal scrap melting method. That is, similar to the smelting reduction method described above, this is a process of melting scrap by the heat generated when the carbon in the carbon-containing fuel is burned by O ₂ gas.

The most important problem in the above process is how to effectively recover the heat generated by the secondary combustion in the molten metal into the molten metal. That is,
About 80% of the heat source (coal combustion heat) added to the furnace is taken out by CO gas, so it is necessary to devise a secondary combustion method in order to effectively utilize the enormous latent heat of combustion that this CO gas has. is there. The following method is known as a prior art related to this secondary combustion method.

In Japanese Patent Laid-Open No. 62-280311, as shown in FIG. 8, "Metal bath 3 produced by smelting reduction
The invention relating to the smelting reduction method characterized in that the metal No. 1 is made into a splash by blowing gas and is made to fly to the secondary combustion zone is disclosed (hereinafter referred to as "prior art I").

Further, Japanese Patent Laid-Open No. 64-68415 discloses that
As shown in FIG. 9, “bottom-blown tuyeres 41, side-blown tuyeres 42
And in a smelting reduction furnace equipped with an upper blowing lance 43,
CO or / and an inert gas is blown from the bottom blowing tuyere 41 together with the Cr ore, and at least a part of the gas flow is
CO or / and an inert gas is blown from the side blowing tuyere 42 so as to hit the molten metal raised portion (A) by the bottom blowing gas, and main O ₂ gas is blown into the molten metal from the upper blowing lance 43, and A method for producing molten stainless steel by smelting reduction, characterized in that Cr ore is melt-reduced by blowing O ₂ gas for secondary combustion into the slag from the side, and then predetermined decarburization treatment is performed. (Hereinafter referred to as "Prior Art II").

Further, Japanese Patent Laid-Open No. 1-205016 discloses that, as shown in FIG. 10, "iron ore is charged into a refining furnace 51 together with a carbonaceous material and a slag-forming agent, and the bottom blowing tuyere 52 and side blowing are performed. A smelting reduction method in which an inert gas, CO or a process gas is blown from a tuyere 53, in which a main O ₂ gas and an O ₂ gas for secondary combustion are blown from an upper blowing oxygen lance 54,
At least a part of the gas flow from the side blowing tuyere 53 is made to hit the molten metal portion (B) raised by the gas blown from the bottom blowing tuyere 52, and powdered carbonaceous material or steam is blown to oxidize the exhaust gas. The invention relating to a smelting reduction method and an apparatus characterized by controlling the temperature is disclosed (hereinafter referred to as "prior art III").

As shown in FIG. 11, Japanese Unexamined Patent Publication No. 61-221322 discloses that "a large amount of slag 61 is held on a metal bath 62 and a part of combustible gas generated in the furnace is oxygen. The heat generated by burning the gas containing the slag 61
To the metal bath 62 or the metal raw material (C) by efficiently stirring or circulating the slag 61 with a gas. (Below,
"Prior art IV").

[0010]

However, the above-mentioned prior arts I to IV have the following problems.

In the prior art I, the metal bath 3 is heated by O ₂ gas blown from the splash forming tuyere 32.
The metal in 1 is blown to the secondary combustion zone on the slag 33. Then, the O blown from the secondary combustion tuyeres 34
Secondary combustion is performed with ₂ gases. In this case, since the secondary combustion is performed on the slag 33, even if a part of the heat generated by the secondary combustion is transferred to the metal, most of the combustion heat is removed by the exhaust gas and cannot be effectively recovered by the metal. Further, since the furnace side refractory becomes high temperature due to the radiant heat of the secondary combustion, the degree of wear of the refractory is large.

In the prior art II, the secondary combustion O ₂ gas blown from the upper blowing lance 43 is used to perform secondary combustion in the slag 44. However, the amount of secondary combustion O ₂ gas blown in is increased. However, even if the slag is strongly stirred by the gas blown from the side blowing tuyere 42, the combustion due to the complete encounter and mixing of the secondary combustion O ₂ gas and the burned gas (CO gas) Have difficulty. That is, the amount of CO gas discharged from the molten metal through the slag layer without encountering the secondary combustion O ₂ gas is considerably large. When the amount of O ₂ gas for secondary combustion is increased in order to improve the secondary combustion rate under such a condition, a part of the O ₂ gas becomes unreacted,
This unreacted O ₂ gas burns on the slag 44, and
Like I, the combustion heat is not used effectively because the exhaust gas carries it away. Further, the degree of wear of the refractory on the furnace side is large due to the radiant heat of the secondary combustion.

The prior art III also attempts to carry out secondary combustion in the slag 55 by the O ₂ gas for secondary combustion blown from the top-blown oxygen lance 54, and in this case also, the same drawbacks as those of the prior art II. have.

The prior art IV has a merit that the secondary combustion is stably performed because the large amount of the slag bath 61 exerts an effect as a buffer of the chemical process or as a heat retaining layer, but the prior art IV is stable. Also has the same drawbacks as the above-mentioned Prior Art II or III.

The present invention has been made in view of the above problems of the prior art, and an object thereof is to realize a stable high secondary combustion rate without damaging the device, It is an object of the present invention to provide a metal refining method capable of effectively recovering heat generated by secondary combustion.

[0016]

In order to achieve the above object, the gist of the present invention is to introduce a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas into a molten metal, the to generate CO gas with obtaining by burning heat by O ₂ gas, the CO gas was further secondary combustion by O ₂ gas to generate heat, metal refining method of smelting a metal material by their thermal In the above, a part of the O ₂ gas does not burn in the molten metal and comes out of the molten metal in an unburned state, and this unburned O ₂ gas performs secondary combustion in the slag bath.
O ₂ gas or O from a position below the upper surface level of the molten metal
_{When a} gas containing ₂ gases is blown and the flow rate of the O ₂ gas or the gas containing O ₂ gas blown is reduced, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas exiting the furnace is decreased, and in reverse _When the flow rate of the gas containing ₂ gas or O ₂ gas is increased, the (CO
₂ / (CO + CO ₂ )) is used to control the flow rate of the gas containing O ₂ gas or the gas containing O ₂ gas by using the relationship of (CO ₂
/ (CO + CO ₂ )) is adjustable, the first invention is a metal refining method, and a metal raw material, a carbon-containing fuel, a slag forming agent, and O ₂ gas are introduced into a molten metal to contain carbon. Carbon of the fuel is burned by O ₂ gas to obtain heat and CO gas is generated, and the CO gas is secondarily burned by O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In the metal refining method, some O ₂ gas does not burn in the molten metal and comes out of the molten metal in an unburned state, and this unburned O ₂ gas performs secondary combustion in the slag bath. ₂ gas is mixed with another gas such as N ₂ gas or O ₂ other than O ₂ , and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal, (O ₂ gas flow rate) /
(CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the furnace outlet gas increases when the (other gas flow rate) ratio decreases, and conversely increases the (O ₂ gas flow rate) / (other gas flow rate) ratio. Then, (CO ₂ / (CO + C
O ₂ )) decreases, and (O ₂ gas flow rate)
A second invention is a metal refining method characterized in that (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or in the furnace outlet gas can be adjusted by controlling the / (other gas flow rate) ratio. , A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into the molten metal, carbon of the carbon-containing fuel is burned by the O ₂ gas to obtain heat and generate CO gas, and the CO gas is generated. Further, in a metal refining method in which secondary combustion is performed with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat, a part of O ₂ gas is not burned in the molten metal and the metal is in an unburned state. As the unburned O ₂ gas exits the molten metal and performs secondary combustion in the slag bath, N ₂ gas, air, etc. around the O ₂ gas flow from the position below the upper surface level of the molten metal around the O ₂ gas flow. A gas flow having a two-layer structure of an inner and outer layers having a gas flow of another kind other than O _2. When the gas is blown into the furnace and the (O ₂ gas flow rate) / (other kind gas flow rate) ratio is decreased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas increases, and conversely (O ₂ gas When the ratio of (flow rate) / (flow rate of other gases) is increased, (CO ₂ / (CO
+ CO ₂ )) is used to control the ratio of (O ₂ gas flow rate) / (other type gas flow rate), and thereby (CO ₂ / (CO + CO ₂ )) of the upper part of the furnace or the furnace outlet gas is controlled.
Is a metal refining method as a third invention, in which a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal, and carbon of the carbon-containing fuel is converted into O ₂ In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. a plurality of large-diameter tuyeres provided in a position and blowing a plurality of small-diameter tuyeres each from the O ₂ gas to the mixed gas of other species gas other than O _2, such as N ₂ gas or air into the furnace, line analysis of CO concentration in the gas in the furnace top or the furnace outlet and the CO ₂ concentration While smelting metallic raw materials, in the furnace top or the furnace exit gas by adjusting the O ₂ gas flow rate and other species gas flow (CO ₂ / (CO +
CO ₂ )) is adjustable, and a metal refining method is characterized as a fourth invention, in which a metal raw material, a carbon-containing fuel, a slag forming agent and O ₂ gas are introduced into a molten metal to Metal refining in which carbon is combusted with O ₂ gas to obtain heat and CO gas is generated, and the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In the method, a part of the O ₂ gas in the molten metal does not burn and leaves the molten metal in an unburned state,
When the unburned O ₂ gas performs secondary combustion in the slag bath, O ₂ gas or a gas containing O ₂ gas is blown from a position below the upper surface level of the molten metal to reduce the molten metal level in the furnace. The upper part of the furnace or the gas at the furnace outlet (CO ₂ /
(CO + CO ₂ )) increases and conversely the level of the molten metal in the furnace increases, (CO ₂ /
(CO + CO ₂ )) is used to control the level of the molten metal in the furnace so that the (CO ₂ / (CO + CO ₂ )) of the upper furnace gas or the furnace outlet gas can be adjusted. A fifth invention is a metal refining method
A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into the molten metal, carbon of the carbon-containing fuel is burned by the O ₂ gas to obtain heat, and CO gas is generated. In a metal refining method of secondarily burning with O ₂ gas to generate heat, and melting and refining a metal raw material by the heat, a metal melt in an unburned state without burning some O ₂ gas in the metal melt Then, the unburned O ₂ gas is blown with O ₂ gas or a gas containing O ₂ gas from a position below the upper surface level of the molten metal so that the unburned O ₂ gas performs secondary combustion in the slag bath, and the pressure in the furnace is reduced. Then, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the outlet gas of the furnace increases, and conversely, when the pressure in the furnace increases, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the outlet gas of the furnace increases. The decreasing pressure can be used to control the furnace pressure. Accordingly, the furnace top or the furnace exit gas _{(CO 2 / (CO + CO} 2)) is a metal refining process, characterized in that it is adjustable to a sixth aspect of the invention,
A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into the molten metal, carbon of the carbon-containing fuel is burned by the O ₂ gas to obtain heat, and CO gas is generated. In a metal refining method of secondarily burning with O ₂ gas to generate heat, and melting and refining a metal raw material by the heat, a metal melt in an unburned state without burning some O ₂ gas in the metal melt out, this as unburnt O ₂ gas makes a secondary combustion within the slag bath, by mixing other species gas other than O _2, such as N ₂ gas or air to the O ₂ gas, the upper surface of the molten metal When the mixed gas is blown into the furnace from a position below the level and the ratio of (O ₂ gas flow rate) / (other type gas flow rate) is reduced, (CO ₂ / (CO + C + C
O ₂ )) increases, and conversely, when the (O ₂ gas flow rate) / (other type gas flow rate) ratio is increased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas decreases. When the level of molten metal in the furnace is decreased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the furnace outlet increases, and conversely, when the level of molten metal in the furnace is increased, By utilizing the relationship of (CO ₂ / (CO + CO ₂ )) to decrease, the ratio of (O ₂ gas flow rate) / (other type gas flow rate) and the level of molten metal in the furnace can be controlled so that the upper part of the furnace or the outlet of the furnace can be controlled. A seventh aspect of the present invention is a metal refining method which is characterized in that (CO ₂ / (CO + CO ₂ )) of gas can be adjusted, and a metal raw material, a carbon-containing fuel, a slag forming agent and O are contained in a molten metal.
₂ gas is introduced, carbon of the carbon-containing fuel is burned by O ₂ gas to obtain heat, and CO gas is generated.
In a metal refining method in which O gas is further secondarily combusted with O ₂ gas to generate heat and the metal raw material is melted and refined by the heat, a part of O ₂ gas is not burned in the molten metal and is unburned. In such a state that the unburned O ₂ gas is secondarily burned in the slag bath after being discharged from the molten metal, N ₂ gas or the like is generated around the O ₂ gas flow from the position below the upper surface level of the molten metal so that the unburned O ₂ gas is secondarily burned. A gas flow having a two-layer structure of an inner and outer layers having a gas flow other than O ₂ such as air is blown into the furnace (O ₂ gas flow rate)
(CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas increases when the / (other gas flow rate) ratio is decreased, and conversely, the (O ₂ gas flow rate) / (other gas flow rate) ratio is increased. When it is increased, (CO ₂ / (CO + CO
₂ )) decreases, and when the level of molten metal in the furnace is decreased, (CO ₂ / (CO +
(CO ₂ )) increases, and conversely, when the level of molten metal in the furnace is increased, (CO ₂ / (CO +
CO ₂ )) is reduced to control the (O ₂ gas flow rate) / (other gas flow rate) ratio and the level of molten metal in the furnace, so that the (CO ₂
/ (CO + CO ₂ )) is adjustable, and the eighth aspect of the invention is a metal refining method, in which a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal to contain carbon. Carbon of the fuel is burned by O ₂ gas to obtain heat and CO gas is generated, and the CO gas is secondarily burned by O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In the metal refining method, a part of the O ₂ gas is not burnt in the molten metal and comes out of the molten metal in an unburned state, and the unburned O ₂ gas is secondarily burned in the slag bath. O from each of a plurality of large diameter tuyere and a plurality of small diameter tuyere provided at a position below the upper surface level of the molten metal.
_While injecting a mixed gas in which other gas other than O ₂ such as N ₂ gas or air into ₂ gas is blown into the furnace to analyze the CO concentration and CO ₂ concentration in the gas in the upper part of the furnace or the outlet of the furnace, When the metal raw material is smelted and refined and the level of the molten metal in the furnace is reduced, (CO ₂ / (CO 2
+ CO ₂ )) increases and conversely the level of the molten metal in the furnace is increased, (CO ₂ / (CO 2
+ CO ₂ )) is reduced to control the O ₂ gas flow rate, the other gas flow rate, and the molten metal level in the furnace, so that the (CO ₂ / (C ₂
O + CO ₂ )) is adjustable, and the metal refining method is characterized as a ninth invention, in which a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal, Carbon is burned with O ₂ gas to obtain heat and CO
In the metal refining method in which a gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat, a part of the O ₂ gas is melted in the molten metal. out the molten metal in the unburned state without combustion, this unburnt O ₂ gas so as to perform the secondary combustion within the slag bath, O ₂ gas to the N ₂ gas and O ₂ than for other species, such as air When the gas is mixed and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal to reduce the (O ₂ gas flow rate) / (other kind gas flow rate) ratio, CO ₂ / (CO + CO ₂ )) increases, and conversely, when the (O ₂ gas flow rate) / (other type gas flow rate) ratio is increased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the furnace outlet gas becomes As the relationship between the decrease and the pressure inside the furnace is decreased, (CO ₂ / (CO + CO ₂ )) increases,
On the contrary, when the pressure inside the furnace is increased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the outlet of the furnace decreases, and the ratio of (O ₂ gas flow rate) / (other gas flow rate) is used. A tenth invention is a metal refining method characterized in that (CO ₂ / (CO + CO ₂ )) of a furnace upper part or a furnace outlet gas can be adjusted by controlling a furnace pressure. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced, carbon of the carbon-containing fuel is burned by the O ₂ gas to obtain heat and CO gas is generated, and the CO gas is further converted to O ₂ gas. In the metal refining method in which secondary combustion is performed to generate heat, and the metal raw material is melted and refined by the heat, in the metal melt, a part of the O ₂ gas does not burn and comes out of the metal melt in an unburned state, as the unburnt O ₂ gas makes a secondary combustion within the slag bath, Blown from the top-level following positions genera melt the O ₂ gas flow gas flow inside and outside the two-layer structure having a O ₂ than the other species gas stream such as N ₂ gas or air to its outer periphery around the into the furnace, ( When the ratio of (O ₂ gas flow rate) / (other type gas flow rate) is decreased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas is increased, and conversely (O ₂ gas flow rate) / (other type gas) increasing the gas flow rate) ratio furnace top or the furnace exit gas _{(CO 2 / (CO + CO} 2)) and the relationship to decrease, reducing the pressure inside the furnace in the furnace top or the furnace exit gas (CO ₂ / (CO + CO ₂ )) increases,
On the contrary, when the pressure inside the furnace is increased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the outlet of the furnace decreases, and the ratio of (O ₂ gas flow rate) / (other gas flow rate) is used. An eleventh aspect of the present invention is a metal refining method characterized in that (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or in the furnace outlet gas can be adjusted by controlling the pressure in the furnace. Introducing a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas into the above, the carbon of the carbon-containing fuel is burned by the O ₂ gas to obtain heat and generate CO gas, and the CO gas is further converted into O ₂ gas. In the metal refining method in which secondary combustion is performed to generate heat, and the metal raw material is melted and refined by the heat, a part of the O ₂ gas in the metal melt does not burn and is discharged from the metal melt in an unburned state. as the unburnt O ₂ gas makes a secondary combustion within the slag bath Mixture obtained by mixing other species gas other than O ₂ such as N ₂ gas or air plurality of large-diameter tuyeres and from each of a plurality of small-diameter tuyeres to O ₂ gas is provided on the upper surface level or lower position of the molten metal When the gas is blown into the furnace, the metal raw materials are melted and refined while the CO concentration and CO ₂ concentration in the gas in the upper part of the furnace or the outlet of the furnace are analyzed, and the pressure in the furnace is reduced, the upper part of the furnace or the outlet of the furnace Gas (CO ₂ / (CO
+ CO ₂ )) increases and conversely the furnace pressure is increased, (CO ₂ / (CO + C
O ₂ )) is used to control the O ₂ gas flow rate, the gas flow rate of other gases, and the pressure in the furnace to control the (CO ₂ / (CO + CO ₂ )) of the furnace upper gas or the furnace outlet gas.
In the twelfth invention, a metal refining method is characterized in that the metal raw material, the carbon-containing fuel, the slag-forming agent, and O ₂ gas are introduced into the molten metal to convert the carbon of the carbon-containing fuel to O. ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. out part of the O ₂ the molten metal in the unburned state gas without combustion in the melt, N ₂ gas this unburnt O ₂ gas so as to perform the secondary combustion within the slag bath, the O ₂ gas Other gas other than O ₂ such as air and air is mixed, and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal, (O ₂ gas flow rate) / (other gas flow rate)
If the ratio is reduced, the (CO ₂
/ (CO + CO ₂ )) increases, and conversely (O ₂ gas flow rate)
When the / (other gas flow rate) ratio is increased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas is decreased, and when the metal melt level in the furnace is decreased, the upper part of the furnace or the furnace outlet and relationship of the gas _{(CO 2 / (CO + CO} 2)) is increased, increasing the furnace the molten metal level in the opposite furnace top or the furnace exit gas _{(CO 2 / (CO + CO} 2)) is reduced, the furnace When the internal pressure is decreased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the outlet gas of the furnace is increased, and conversely, when the internal pressure is increased, (CO ₂ / (CO + CO 2 ₂ )) is used to control the (O ₂ gas flow rate) / (other gas flow rate) ratio, the level of molten metal in the furnace, and the pressure in the furnace. that _{(CO 2 / (CO + CO} 2)) are possible adjustment The metal refining method as the thirteenth invention, by introducing a metal material and a carbon-containing fuel and Zokasu agent and O ₂ gas into the molten metal, and a carbon of a carbon-containing fuel is burned by O ₂ gas heat and symptoms And generate CO gas,
In the metal refining method in which the CO gas is further secondarily combusted with O ₂ gas to generate heat and the metal raw material is melted and refined by the heat, a part of the O ₂ gas is not burned in the molten metal and is not yet burned. This unburned O _{2 is} emitted from the molten metal in a burning state.
In order to carry out secondary combustion of the gas in the slag bath, there is a gas flow of another kind other than O ₂ such as N ₂ gas or air around the O ₂ gas flow from the position below the upper surface level of the molten metal. When the gas flow of the two-layer structure of the inner and outer layers is blown into the furnace and the (O ₂ gas flow rate) / (other gas flow rate) ratio is decreased, the (CO ₂ / (CO + CO ₂ )) of the upper furnace interior or the furnace outlet gas increases. On the contrary, when the (O ₂ gas flow rate) / (other type gas flow rate) ratio is increased, (CO ₂ / (CO 2
+ CO ₂ )) decreases, and when the level of molten metal in the furnace is decreased, (CO ₂ /
(CO + CO ₂ )) increases and conversely the level of the molten metal in the furnace increases, (CO ₂ /
(CO + CO ₂ )) decreases, and when the pressure in the furnace is decreased, (CO ₂ / (CO 2
+ CO ₂ )) increases and conversely the furnace pressure is increased, (CO ₂ / (CO + C
O ₂ )) decreases, and (O ₂ gas flow rate)
(CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or in the furnace outlet gas can be adjusted by controlling the / (other gas flow rate) ratio, the level of molten metal in the furnace, and the pressure in the furnace. A metal refining method according to the fourteenth invention is used, a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal, and carbon of the carbon-containing fuel is burned by the O ₂ gas to obtain heat. At the same time, CO gas is generated, the CO gas is further secondarily burned by O ₂ gas to generate heat, and in the metal refining method of melting and refining the metal raw material by the heat, a part of O ₂ is melted in the metal melt. A plurality of large diameters are provided at positions below the upper surface level of the molten metal so that the gas does not burn but comes out of the molten metal in an unburned state and the unburned O ₂ gas performs secondary combustion in the slag bath. N ₂ from each tuyere and a plurality of small-diameter tuyeres to O ₂ gas A scan and such as air mixed gas of O ₂ than the other species gas blowing into the furnace, smelting the metal material while analysis of CO concentration and the CO ₂ concentration in the gas in the furnace top or the furnace outlet And the level of the molten metal in the furnace is decreased, the (CO
₂ / (CO + CO ₂ )) increases and conversely the level of molten metal in the furnace increases, the (CO
₂ / (CO + CO ₂ )) decreases, and when the pressure inside the furnace is decreased, (CO ₂ /
(CO + CO ₂ )) increases, and conversely, when the pressure inside the furnace is increased, (CO ₂ / (CO + C ₂
O ₂ )) is decreased to control the O ₂ gas flow rate, the other gas flow rate, the molten metal level in the furnace, and the in-reactor pressure to control the (CO ₂
The 15th invention is a metal refining method characterized in that / (CO + CO ₂ )) is adjustable.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention applied to an iron ore smelting reduction furnace will be described below with reference to the accompanying drawings.

FIG. 1 is a sectional view of an apparatus for carrying out the metal refining method of the present invention. In FIG. 1, 1 is an iron ore smelting reduction furnace in which a refractory brick 2 is stretched on the inner surface, and a large-diameter bubble-like oxygen (G ₁ ) is blown into the bottom of the furnace with respect to the metal melt 3 in the furnace. A bottom blowing tuyere 4 and a stirring gas blowing nozzle 5 are provided, and a taphole 6 is provided in the vicinity thereof. A slag bath 7 on the molten metal 3 is provided with a slag outlet 8 and a side blowing tuyer 9 of stirring gas on the side wall of the furnace, and an exhaust gas duct 10 is connected to the opening of the furnace top. Shoot 1 for charging iron ore preheated / pre-reduced in a pre-heated / pre-reduced fluidized bed furnace (not shown) into the furnace
1 and carbon-containing fuel and chute 12 for charging slag forming agent
Is provided. 13 is a thermometer for detecting the gas temperature in the upper part of the furnace, 14 is a gas sampling device, and 15 is CO and CO.
₂ analyzers. Reference numeral 16 is a conversion controller, and 17 is a control valve for controlling the O ₂ blowing amount. The smelting reduction furnace in this embodiment has the same meaning as a metal refining device. Further, the tuyere provided at a position below the upper surface level of the molten metal in the present invention corresponds to the large-diameter bottom-blowing tuyere 4 in this embodiment.

FIG. 2 is a view showing a state in which an upper-blown O ₂ lance 18 is charged into the slag bath 7 from the top of the furnace.

Next, the operation of the present invention having the above-described structure will be described below in order in relation to each step / factor. (1) Basic process of secondary combustion rate control method by metal refining method according to the present invention (action in molten metal) When the diameter of bubble-like oxygen blown from bottom blowing tuyere 4 of the furnace bottom is small, this The total amount of oxygen reacts with the carbon dissolved in the molten metal 3 as shown in the following formula (a) to become CO gas. C + 1/2 O ₂ → CO (a) However, since the bottom blowing tuyere 4 has a large diameter and the diameter of the bubble-like oxygen G ₁ is large, only the surface portion of the bubble-like oxygen G ₁ reacts with carbon to form CO gas. , Some of the CO gas reacts with the remaining oxygen in the bubbles as shown in the following equation (b) to react with CO ₂ and further with C to rise again as CO gas, but the bubbles are large. The reaction is not completed within the time when it passes through the molten metal 3. CO + 1/2 O ₂ → CO ₂ , CO ₂ + C → 2CO (b) That is, the gas leaving the molten metal 3 is CO, O ₂ and CO ₂
Becomes a coexisting gas of and floats up in the slag bath 7. Then, the above reactions (a) and (b) in the molten metal 3 of this coexisting gas
The heat generated as a result is given to the molten metal 3.

On the other hand, the ore charged into the furnace from the chute 11 at the top of the furnace is melted by receiving the heat generated by the reactions of the above (a) and (b), and the carbon contained in the molten metal. Is reduced to become hot metal. The hot metal thus produced is taken out from the tap hole 6 at the bottom of the furnace.

Carbon in the molten metal is successively consumed and reduced by the above reaction, so that coal is appropriately charged into the furnace from the chute 12 in order to supplement this carbon amount.

(Operation in Slag Bath) CO, O ₂ and CO ₂ that have entered the slag bath 7 from the molten metal 3 as described above.
The coexisting gas of is rising like bubbles in the slag bath 7,
The gas inside is mixed with the passage of time during the rise,
CO and O ₂ in the gas react to form CO ₂ .

That is, the O ₂ gas for secondary combustion and the CO gas are not separated as in the prior art, but they enter the slag bath 7 with both O ₂ and CO included so that each bubble burns. Therefore, the secondary combustion efficiency in the slag bath 7 is extremely good. The combustion heat is given to the slag bath 7.
The slag bath 7 is generated in the slag bath 7 because it is vigorously stirred or refluxed by the stirring gas blown into the molten metal 3 and the slag bath 7 from the side blowing tuyere 9 on the side wall of the furnace and the blowing nozzle 5 on the bottom of the furnace. The combustion heat is transferred to the molten metal 3 through the interface between the slag bath 7 and the molten metal 3.

The combustion exhaust gas after the combustion heat of the raw material (carbon) is transferred to the molten metal extremely efficiently in this way rises from the slag bath 7 to the upper space of the furnace and passes through the exhaust gas duct 10 to the outside of the furnace. Is discharged to.

Further, in the above reaction process, slag is appropriately discharged from the slag port 8 provided on the side wall of the furnace in order to keep the slag amount in the furnace at a predetermined amount, and the chute 12 at the top of the furnace.
A slag forming agent is appropriately added from.

The basic process in the case of bottom blowing is as described above, but it is also possible to perform top / bottom blowing in combination with top blowing. For example, the coal is a carbon supply source to the molten metal 3 contains volatile components to some extent, since the volatile components reach the slag bath 7 by raising the molten metal 3 middle, top-blown O ₂ lance 18 (see FIG. 2) or the oxygen blown into the slag bath 7 from the side blowing tuyere 9 burns the volatile components to generate heat, and the heat generated in the slag bath 7 is as described above. Since it is sufficiently stirred, it is efficiently transferred to the molten metal. In this way, the retained heat of the volatile components can be effectively recovered.

Whether the bottom blowing or the top / bottom blowing is performed, the basic characteristic common to the present invention is that "unburned O ₂ is left in the gas entering the slag bath 7 from the molten metal 3". As it is, the unburned O ₂ is secondarily combusted in the slag bath 7. ”As a method therefor, the following method can be adopted in addition to the above method.

A method of blowing long-tailed oxygen (G ₂ ) having a large diameter as shown in FIG. By increasing the amount of oxygen blown in, a long-tailed shape is formed, but when this diameter is small, the long-tailed oxygen becomes almost CO gas. Therefore, by increasing the oxygen diameter, only the surface becomes CO gas,
Unburned oxygen remains inside the gas that enters the slag bath 7 from the molten metal 3. As a result, the same efficient secondary combustion as above can be expected. As shown in FIG. 7, a method in which microbubble oxygen (G ₀ ) and large bubble oxygen (G ₁ ) are mixed. Micro bubble oxygen G
_{Although 0} is mostly CO gas in the molten metal 3, it is expected that secondary combustion will be performed in the slag bath 7 by unburned oxygen in the large-diameter bubble-like oxygen G ₁ to improve the secondary combustion rate. .. Also,
As a method similar to this method, in the above method,
It is also possible to employ a method of simultaneously blowing microbubble oxygen or long-diameter oxygen having a small diameter.

(2) Factors that change the secondary combustion rate The above is the basic process of the secondary combustion rate control method by the metal refining method according to the present invention. An example of the limiting condition for "a part of the O ₂ gas blown from a position below the upper surface level to leave the molten metal in an unburned state" is shown in FIG. As is clear from the figure, the progress of the secondary combustion of the present invention is influenced by three factors of "depth of molten metal", "tuyere diameter", and "tuyere blowing gas flow velocity". Therefore, by appropriately combining these factors to control the secondary combustion, it is possible to adjust the production amount of the molten metal, reduce the basic unit of the auxiliary raw material, and protect the equipment of the smelting reduction furnace. Next, the effect of each of the above factors will be described.

Depth of molten metal If the depth of the molten metal becomes shallow, the contact time between the blown O ₂ gas and the molten metal becomes short, and therefore CO—O ₂ —CO that enters the slag bath from the molten metal ₂ The amount of unburned oxygen in the coexisting gas increases. However, when the depth of this molten metal is too shallow, unburned oxygen is not consumed in the slag bath,
This excess unburned oxygen burns on the slag bath, resulting in
This may lead to an increase in the unit consumption of auxiliary raw materials (coal, etc.) and wear of refractory materials in the furnace. On the contrary, if the depth of the molten metal becomes deeper, the contact time between the blown O ₂ gas and the molten metal becomes longer, so that the CO-O ₂ -C which enters the slag bath from the molten metal.
The amount of unburned oxygen in the O ₂ coexisting gas is reduced. Therefore, the secondary combustion rate may decrease, which may lead to a reduction in the amount of molten metal produced. Therefore, it is necessary to set the depth of the molten metal to an appropriate range for the above reasons, and it is not preferable that the depth of the molten metal be 300 mm or less in order to maintain stable operation. On the other hand, the upper limit of the depth of the molten metal is 1 in order to leave unburned O ₂ gas in the gas leaving the molten metal.
It is preferably 000 mm. In this way, the secondary combustion rate can be controlled by changing the depth of the molten metal.

Tuyere diameter (diameter corresponding to the diameter of oxygen blown into the metal melt from a position below the upper surface level of the metal melt)
As described above, in order to perform effective secondary combustion, it is preferable that the diameter of oxygen is larger. For that purpose, it is necessary to increase the diameter of the tuyere. When is constant, the secondary combustion rate changes with the tuyere gas flow velocity. For example, according to FIG. 4, the depth of molten metal is 300 mm.
When the tuyere diameter is 30 mm, the tuyere blowing gas flow velocity is 200 m /
In the case of sec or less, all the blown O ₂ gas reacts with C in the molten metal to become CO gas. On the contrary, when the tuyere blowing gas flow velocity is higher than 200 m / sec, unburned O ₂ gas comes to be mixed in the gas discharged from the molten metal, and as the blowing gas flow velocity increases, the unburned O ₂ gas increases. Will increase in quantity. Then, the unburned O ₂ gas burns with the CO gas on the molten metal (in the slag bath) (that is, undergoes secondary combustion) to become CO ₂ . This secondary combustion rate is (unburned O ₂
The amount of gas) / (total amount of injected O ₂ gas), which is shown in Table 1 below, as an example of the secondary combustion rate when the molten metal depth is 300 mm.

[0033]

[Table 1]

There are, for example, the following two methods for increasing and decreasing the tuyere blowing gas flow velocity. I. A method of directly increasing or decreasing the tuyere blowing gas flow velocity by increasing or decreasing the blown oxygen flow rate. B. This is a method of increasing or decreasing the tuyere blowing gas flow velocity by changing the actual pressure of the tuyere gas by changing the pressure inside the furnace. It is possible to increase the mouth-blowing gas flow rate, or to decrease the tuyere-blowing gas flow rate by increasing the furnace pressure to reduce the actual volume of the tuyere-blowing gas.

(3) Secondary Burning Rate and CO ₂ Ratio in Exhaust Gas The effect on the secondary burning rate by changing the above-mentioned factors is that CO concentration in the gas in the upper part of the furnace sampled by the gas sampling device 14 and It can be known by analyzing the CO ₂ concentration with the analyzer 15. That is, "the CO ₂ concentration in the gas in the upper part of the furnace is high and the CO concentration is low."
Indicates that "secondary combustion is being performed efficiently,"
On the contrary, "the CO ₂ concentration in the gas is low and the CO concentration is high" means "the efficiency of secondary combustion is low".
Is. Therefore, (CO ₂ concentration) / (CO
If the ratio (concentration + CO ₂ concentration) (also referred to as “CO ₂ ratio in exhaust gas” in the present specification) is known, this CO _{2 in} exhaust gas
An effective action can be taken by using the ratio as a guideline for determining the efficiency of secondary combustion, and that point will be described below.

(4) CO ₂ Ratio in Exhaust Gas and Operating Method A specific operating method will be described depending on whether the CO ₂ ratio in the exhaust gas is smaller or larger than the initially set range.

(When the CO ₂ ratio in the exhaust gas is smaller than the initially set range) In this case, since the secondary combustion rate has decreased, the tuyere-blown O ₂ gas flow velocity (oxygen flow rate) can be increased. Good. Then, the contact time between the O ₂ gas and the molten metal becomes short, so that C in the gas discharged from the molten metal is reduced.
A large amount of unburned O ₂ remains together with O and CO ₂ . This unburned O ₂ is secondarily burned with CO on the molten metal (in the slag bath) to form CO ₂ . As a result, CO _{2 in} the exhaust gas
The ratio will improve.

(When the CO ₂ ratio in the exhaust gas becomes larger than the initially set range) In this case, it is shown that the secondary combustion is performed with extremely high efficiency, but at the same time, the gas temperature in the furnace rises. In some cases, it is necessary to suppress secondary combustion from the viewpoint of equipment protection. For that purpose, the tuyere blowing gas flow rate (oxygen flow rate) may be reduced. Then, since the contact time between the O ₂ gas and the molten metal becomes long,
Almost all of this O ₂ gas is consumed in the reaction with the dissolved carbon in the molten metal, the main components of the coexisting gas leaving the molten metal are CO and CO ₂ , and the unburned O ₂ gas is reduced. As a result, the CO ₂ ratio in the exhaust gas decreases.

As described above, the oxygen flow rate is an important factor that influences the secondary combustion rate and an important control item in terms of equipment protection, and the oxygen flow rate also plays an important role in adjusting the production amount. Fulfill. That is, the amount of oxygen determines the total amount of heat generated by secondary combustion. For example, in order to protect the refractory in the furnace, the gas temperature in the upper part of the furnace detected by the thermometer 13 is the heat resistant temperature of the refractory. (About 1700-1
When the temperature reaches 800 ° C., the control valve 17 can be adjusted to reduce the flow rate of oxygen blown into the furnace, suppress the total combustion heat quantity, and lower the maximum furnace temperature. The amount of molten metal produced can be adjusted depending on the amount of blown oxygen.

(5) Stirring promotion effect by mixing inert gas with O ₂ gas and adjustment of secondary combustion rate As described in detail above, in order to achieve the object of the present invention, large O 2 While blowing ₂ gas from the top level following the position of the molten metal is at a maximum point of the purpose of "improving the secondary combustion rate by lowering the reaction volume of O _2" and "reaction promotion by stirring action" An inert gas can also be used. Therefore, next, a method and its action in the case of blowing an inert gas into the furnace will be described in detail.

(Melting of molten metal) There is a slag bath 7 on top of the molten metal 3, and from the viewpoint of metallurgical effect (for example, for adsorbing S in the molten metal to the slag), the molten metal 3 and the slag bath 7 are It is necessary to enhance the contactability between the two baths, and therefore, if an inert gas is blown into the molten metal 3 and the slag bath 7 and the mixture is stirred, the contactability between the two baths is enhanced.

In the present invention, since the secondary combustion is performed in the slag bath 7, the temperature of the slag bath 7 is raised. Therefore, in order to transfer the heat of the slag bath 7 to the molten metal 3 and efficiently promote the reaction, if an inert gas is blown into the molten metal 3 and the slag bath 7 and stirred, the contact between the two baths is improved. In the molten metal 3, the heat generation amount when a part of O ₂ reacts with C, the heat absorption amount when the iron oxide is reduced, and the heat amount transferred from the slag bath 7 to the metal melt 3 are kept in a good balance. , The reaction proceeds efficiently.

For the above stirring, an inert gas such as N ₂ may be blown into the furnace from the side blowing tuyere 9 in FIG. 1 or the blowing nozzle 5 at the bottom.

(Improving Secondary Burning Rate) Ultimately, the purpose is to improve the secondary burning rate, but the reaction process can be divided into the following two methods.

Reduction of O ₂ Reaction Amount by Mixing O ₂ Gas with Inert Gas This case can be further divided into two cases, that is, the case where the total gas flow rate in the furnace is increased and the case where it is not increased. (a) When increasing the total blown gas flow rate in the furnace When an inert gas such as N ₂ gas is added to the O ₂ gas, the total blown gas flow rate in the furnace increases, and the tuyere blown gas flow velocity increases, As a result, the secondary combustion rate can be increased. For example, when the depth of molten metal is 300 mm, as shown in Table 1 showing the calculation results, when the O ₂ gas is blown under the conditions of the tuyere diameter of 50 mm and the tuyere blowing gas velocity of 200 m / sec, the secondary combustion rate Is 30%, but with this O ₂ gas, O ₂
If 50% of N ₂ 1.5 adding and mixing the flow rate of the gas flow, tuyere blowing gas flow rate 300 meters / sec, and the
The secondary combustion rate is 45% or more. Become 45% or more, since being added to the O ₂ gas is N ₂ gas inert, reaction with O ₂ gas and C in the molten metal 3 is suppressed, the slag from molten metal 3 the amount of unburnt O ₂ gas O ₂ gas entering the bath 7 is because it is expected that more than blow gas is O ₂ only.

(B) When the total blown gas flow rate in the furnace is not increased In this case, the larger the amount of N ₂ gas mixed in the O ₂ gas, the more the reaction amount of O ₂ gas and C in the molten metal 3 becomes. On the contrary, the secondary combustion rate is increased. For example, from Table 1, when the metal melt depth is 300 mm, the tuyere diameter is 30 mm, and the tuyere blowing gas flow velocity is 300 m / sec, the secondary combustion rate is 20% when the blowing gas is O ₂ , but the gas flow rate is 20%. Assuming that they are the same, 50% of the blown gas is O ₂ , and the remaining 50
If% is replaced with N ₂ , the secondary combustion rate will be improved to 30%.

[0047] As an example of the equipment for the incorporation of N ₂ gas thus the furnace blowing O ₂ gas, as shown in FIG. 5, in parallel with the O ₂ supply line 19 which carries the O ₂ N ₂
A N ₂ supply line 20 for transporting the gas is installed, and the indicated value of the conversion controller 16 or 21 is changed according to the analysis value of the CO ₂ concentration in the furnace upper gas and the CO concentration by the analyzer 15, and the control valve The O ₂ flow rate passing through 17 or the N ₂ flow rate passing through the control valve 22 is increased / decreased, both gases are mixed by the mixer 23, and then blown into the furnace from the bottom blowing tuyere 4 having a large diameter at the bottom of the furnace.

Although the bottom blowing tuyere 4 shown in FIG. 5 has a large diameter, as shown in FIG. 7, each of the three large diameter bottom blowing tuyere 4 has a small diameter bottom blowing tuyere. 4a are arranged side by side and connected to the large-diameter bottom blowing tuyeres 4, O ₂ supply line 19, N ₂ supply line 20, or small-diameter bottom blowing tuyere 4a O ₂ supply line 26, N ₂ By adjusting the gas flow rate of each gas supply line of the supply line 27, the CO ₂ ratio in the exhaust gas can be changed and the secondary combustion rate can be adjusted in the same manner as above. In this case, the small-diameter bottom-blowing tuyere 4a
The effect of is basically the same as the effect of the large-diameter bottom blowing tuyere 4 described above, except for "the amount of unburned O ₂ in the gas discharged from the molten metal 3 to the slag bath 7 depending on the diameter". You can expect the same effect. 28 and 29 are conversion controllers,
30 is a mixer.

Reduction of reaction amount of O ₂ gas in the metal melt by separating O ₂ gas from the metal melt 3 As shown in FIG. 6 (a), N ₂ supply is performed in parallel with the O ₂ supply line 19. A line 20 is provided, and three large-diameter bottom blowing tuyeres 4A at the bottom of the furnace are directly connected to each of the O ₂ supply line 19 and the N ₂ supply line 20. These tuyere 4A are shown in FIG. 6 (b).
As shown in the enlarged view of FIG. 2, a double-tube structure is adopted. O ₂ gas is blown from the inner tube 24, and N ₂ is supplied so as to surround the O ₂ gas.
If the gas is blown from the outer tube 25, the O ₂ gas and the molten metal 3 are separated from each other by the N ₂ gas near the tuyere, and as a result, the reaction amount of the O ₂ gas in the molten metal 3 is increased. The amount of unburned O ₂ gas contained in the molten metal 3 which is decreased, and the secondary combustion rate is improved.

In addition, the maximum temperature in the furnace can be lowered by utilizing the effect of reducing the O ₂ reaction amount by adding an inert gas such as N ₂ to oxygen, and the effect of protecting the refractory in the furnace can be expected. .. Although N ₂ gas was used as the inert gas in each of the above-mentioned examples, air may be used as a gas other than N ₂ . Since O _{2 is} also contained in the air, the effect of reducing the amount of expensive O ₂ used can be expected in this case. In any of the above embodiments, oxygen may be supplied from the top-blowing lance to supplement the total amount of oxygen required for metallurgy in the refining furnace.

[0051]

Since the present invention is configured as described above, it has the following effects. Since the contact and reaction between the secondary combustion O ₂ gas and the burned gas (CO gas) are performed extremely efficiently, a high secondary combustion rate can be obtained.

The secondary combustion is mainly performed in the slag bath, the heat generated by the secondary combustion is effectively absorbed by the slag bath, and this heat is efficiently transferred to the molten metal through the interface of the molten metal in contact with the slag bath. .. Therefore, the retained reaction heat of the gas discharged from the furnace is small, and the efficiency of recovering the heat generated in the furnace is extremely high.

Since the secondary combustion is uniformly carried out in the slag bath or the molten metal, the molten metal is not locally heated, and therefore, the refractory in the furnace is less worn.

By controlling the O ₂ gas flow rate or the inert gas flow rate blown from near the bottom of the furnace, or by surrounding the O ₂ gas with an inert gas, the reaction amount of O ₂ gas is reduced and the secondary combustion rate is increased. Can be controlled easily.

By controlling the O ₂ gas flow rate or the inert gas flow rate blown from near the bottom of the furnace, the maximum temperature inside the furnace can be lowered and the refractory inside the furnace can be protected.

[Brief description of drawings]

FIG. 1 is a sectional view of an apparatus for carrying out the metal refining method of the present invention.

FIG. 2 is a sectional view of an apparatus for carrying out the metal refining method of the present invention having a top-blown O ₂ lance.

FIG. 3 is a cross-sectional view of an apparatus for carrying out the metal refining method of the present invention, which shows the case of blowing a large-diameter long-tailed oxygen.

FIG. 4 is a diagram showing a relationship among a maximum metal melt depth, a tuyere diameter, and a tuyere injection gas flow velocity required for remaining unburned O ₂ gas in the gas leaving the metal melt.

FIG. 5 is a cross-sectional view of an apparatus for carrying out the metal refining method of the present invention showing the case where a mixed gas of O ₂ gas and an inert gas is blown in.

FIG. 6 (a) is a cross-sectional view of an apparatus for carrying out the metal refining method of the present invention showing a case where O ₂ gas and an inert gas are blown in a double tubular form, and (b) is an enlarged view of a tuyere. Is.

FIG. 7 is a cross-sectional view of an apparatus for carrying out the metal refining method of the present invention, showing a case where a mixed gas of O ₂ gas and an inert gas is blown from each of a plurality of large diameter tuyere and a plurality of small diameter tuyere. Is.

FIG. 8 is a cross-sectional view of a metal refining apparatus of Prior Art I.

FIG. 9 is a cross-sectional view of a metal refining apparatus of Prior Art II.

FIG. 10 is a cross-sectional view of a metal refining apparatus of Prior Art III.

FIG. 11 is a cross-sectional view of a metal refining device of Prior Art IV.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Melt reduction furnace 3 ... Molten metal 4, 4A ... Bottom blowing tuyere 7 ... Slag bath 13 ... Thermometer 14 ... Gas sampling device 15 ... Analyzer 18 ... Top blowing O ₂ lance 19, 26 ... O ₂ supply line 20 , 27 ... N ₂ supply line

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Kenichi Yajima 3-1-1 Higashikawasaki-cho, Chuo-ku, Kobe-shi, Hyogo Kawasaki Heavy Industries Ltd. Kobe factory (72) Satoshi Tatsuda Higashi-kawasaki, Chuo-ku, Kobe-shi, Hyogo 3-1, 1-1, Kawasaki Heavy Industries Ltd. Kobe factory

Claims (15)

[Claims] [Claim 1] introducing a metal source and carbon-containing fuel and Zokasu agent and O ₂ gas into the molten metal, O ₂ carbon of the carbon-containing fuel
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. When the O ₂ gas or the gas containing the O ₂ gas is blown from the position and the flow rate of the blown O ₂ gas or the gas containing the O ₂ gas is decreased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the furnace outlet gas becomes reduced, increasing the flow rate of the gas containing O ₂ gas or O ₂ gas blown in the opposite furnace top or the furnace exit gas (CO ₂ / (C
O + CO ₂ )) is used to increase the O
By controlling the flow rate of the gas containing ₂ gas or O ₂ gas, (CO ₂ / (CO 2
+ CO ₂ )) is adjustable, a metal refining method. 2. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. out part of the O ₂ the molten metal in the unburned state gas without combustion in the melt, N ₂ gas this unburnt O ₂ gas so as to perform the secondary combustion within the slag bath, the O ₂ gas Other gas other than O ₂ such as air and air is mixed, and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal, (O ₂ gas flow rate) / (other gas flow rate)
If the ratio is reduced, the (CO ₂
/ (CO + CO ₂ )) increases, and conversely (O ₂ gas flow rate)
By using the relationship that (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the furnace outlet decreases when the ratio of / (other type gas flow rate) is increased, (O ₂ gas flow rate) / (other type gas flow rate) ) The metal refining method is characterized in that the (CO ₂ / (CO + CO ₂ )) of the furnace upper part or the furnace outlet gas can be adjusted by controlling the ratio. 3. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into the molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. the O ₂ gas flow gas flow inside and outside the two-layer structure having a O ₂ than the other species gas stream such as N ₂ gas or air to the outer periphery around a blown into the furnace from the location, (O ₂
When the (gas flow rate) / (other type gas flow rate) ratio is decreased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the furnace outlet gas increases, and conversely (O ₂ gas flow rate) / (other type gas flow rate) ) Ratio, the (CO ₂ /
By using the relationship that (CO + CO ₂ )) decreases, (O ₂
By controlling the (gas flow rate) / (gas flow rate of other gas) ratio, the (CO ₂ / (CO + C + C
O ₂ )) is adjustable, a metal refining method. 4. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. a plurality of large-diameter tuyeres provided in a position and blowing a plurality of small-diameter tuyeres each from the O ₂ gas to the mixed gas of other species gas other than O _2, such as N ₂ gas or air into the furnace, By melting and refining the metal raw material while analyzing the CO concentration and CO ₂ concentration in the gas in the upper part of the furnace or the outlet part of the furnace, and adjusting the O ₂ gas flow rate and the other gas flow rate, the upper part of the furnace or the furnace outlet Gas (CO ₂ / (CO +
CO ₂ )) is adjustable, a metal refining method. 5. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. When the O ₂ gas or a gas containing O ₂ gas is blown from the position to reduce the level of the molten metal in the furnace, (CO ₂ / (CO + C + C
O ₂ )) increases and conversely the level of the molten metal in the furnace is increased, (CO ₂ / (CO + C + C
O ₂ )) is reduced to control the level of molten metal in the furnace so that (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas can be adjusted. Metal refining method. 6. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. When the O ₂ gas or a gas containing O ₂ gas is blown from the position and the pressure inside the furnace is reduced, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the outlet gas of the furnace increases, and conversely the pressure inside the furnace increases. By making use of the relationship that (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the outlet of the furnace is utilized, by controlling the pressure in the furnace, (CO ₂ / ( CO + CO ₂ )) is adjustable Metal refining method to collect. 7. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. out part of the O ₂ the molten metal in the unburned state gas without combustion in the melt, N ₂ gas this unburnt O ₂ gas so as to perform the secondary combustion within the slag bath, the O ₂ gas Other gas other than O ₂ such as air and air is mixed, and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal, (O ₂ gas flow rate) / (other gas flow rate)
If the ratio is reduced, the (CO ₂
/ (CO + CO ₂ )) increases, and conversely (O ₂ gas flow rate)
When the / (other gas flow rate) ratio is increased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas is decreased, and when the metal melt level in the furnace is decreased, the upper part of the furnace or the furnace outlet Utilizing the relationship that (CO ₂ / (CO + CO ₂ )) in the gas increases and conversely, when the level of molten metal in the furnace increases, (CO ₂ / (CO + CO ₂ )) in the upper furnace gas or the furnace outlet gas decreases. By controlling the (O ₂ gas flow rate) / (other gas flow rate) ratio and the molten metal level in the furnace, the (CO ₂ / (CO + C + C)
O ₂ )) is adjustable, a metal refining method. 8. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. the O ₂ gas flow gas flow inside and outside the two-layer structure having a O ₂ than the other species gas stream such as N ₂ gas or air to the outer periphery around a blown into the furnace from the location, (O ₂
If the ratio of (gas flow rate) / (gas flow rate of other gas) is decreased, (CO ₂ / (CO + CO ₂ )) in the upper furnace gas or the furnace outlet gas increases, and conversely (O ₂ gas flow rate) / (other gas flow rate) ) Ratio, the (CO ₂ / (C ₂
O + CO ₂ )) decreases, and when the level of molten metal in the furnace is decreased, (CO ₂ /
(CO + CO ₂ )) increases and conversely the level of the molten metal in the furnace increases, (CO ₂ /
By using the relationship that (CO + CO ₂ )) decreases, (O ₂
(CO ₂ / (CO + CO ₂ )) of the furnace upper part or the furnace outlet gas can be adjusted by controlling the (gas flow rate) / (other type gas flow rate) ratio and the molten metal level in the furnace. Metal refining method. 9. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O ₂
In a metal refining method in which a gas is combusted to obtain heat and at the same time CO gas is generated, the CO gas is secondarily combusted with O ₂ gas to generate heat, and the metal raw material is melted and refined by the heat. In order that some of the O ₂ gas in the molten metal is not burned and comes out of the molten metal in an unburned state, and this unburned O ₂ gas is subjected to secondary combustion in the slag bath, the temperature is lower than the upper level of the molten metal. a plurality of large-diameter tuyeres provided in a position and blowing a plurality of small-diameter tuyeres each from the O ₂ gas to the mixed gas of other species gas other than O _2, such as N ₂ gas or air into the furnace, When the metal raw material is melted and refined and the level of the molten metal in the furnace is reduced while analyzing the CO concentration and CO ₂ concentration in the gas in the upper part of the furnace or the outlet part of the furnace, the (CO ₂ / (CO + CO ₂₎₎ is increased, the furnace the molten metal in the opposite By utilizing the relationship that when increasing the bell furnace top or the furnace exit gas _{(CO 2 / (CO + CO} 2)) is reduced to control the O ₂ gas flow rate and other species gas flow rate and furnace the molten metal level Therefore, the (CO ₂ / (CO + CO ₂ )) of the gas inside the furnace or the gas at the furnace outlet can be adjusted. 10. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O _2.
In the metal refining method of combusting with 2 gas to obtain heat and generating CO gas, further burning the CO gas with O ₂ gas to generate heat, and melting and refining the metal raw material with the heat. Some O _{2 in the} molten metal
Gas exits from the molten metal in the unburned state without combustion, as the unburnt O ₂ gas makes a secondary combustion within the slag bath, O ₂
A gas other than O ₂ such as N ₂ gas or air is mixed with the gas, and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal to obtain (O ₂ gas flow rate) / (other gas flow rate). )
If the ratio is reduced, the (CO ₂
/ (CO + CO ₂ )) increases, and conversely (O ₂ gas flow rate)
When the / (other gas flow rate) ratio is increased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas is decreased, and when the furnace pressure is decreased, the upper part of the furnace or the furnace outlet gas is decreased. (CO ₂ / (CO + CO ₂ )) increases, and conversely, when the pressure in the furnace is increased, the (CO 2
₂ / (CO + CO ₂ )) is used,
By controlling the (O ₂ gas flow rate) / (other gas flow rate) ratio and the furnace pressure, the (CO 2
₂ / (CO + CO ₂ )) is adjustable, which is a metal refining method. 11. A method for introducing carbon into a carbon-containing fuel by introducing a metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas into a molten metal.
_In the metal refining method of combusting with 2 gas to obtain heat and generating CO gas, further burning the CO gas with O ₂ gas to generate heat, and melting and refining the metal raw material with the heat. Some O _{2 in the} molten metal
The gas flows out of the molten metal in an unburned state without burning, and the unburned O ₂ gas conducts secondary combustion in the slag bath so that the O ₂ gas flow is centered from a position below the upper level of the molten metal. As a gas flow having a two-layer structure of inner and outer layers having a gas flow of other species other than O ₂ such as N ₂ gas and air on its outer periphery, is blown into the furnace (O
( ₂ gas flow rate) / (other gas flow rate) ratio decreases (CO ₂ / (CO + CO ₂ ))
When the ratio of (O ₂ gas flow rate) / (other type gas flow rate) is increased, (CO ₂ /
(CO + CO ₂ )) decreases, and when the pressure in the furnace is decreased, (CO ₂ / (CO 2
+ CO ₂ )) increases and conversely the furnace pressure is increased, (CO ₂ / (CO + C
O ₂ )) decreases, and (O ₂ gas flow rate)
By controlling the / (other gas flow rate) ratio and the furnace pressure, (CO ₂ / (CO + CO + CO 2
₂ )) is adjustable, a metal refining method. 12. A metal raw material, a carbon-containing fuel, a slag-forming agent and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O _2.
In the metal refining method of combusting with 2 gas to obtain heat and generating CO gas, further burning the CO gas with O ₂ gas to generate heat, and melting and refining the metal raw material with the heat. Some O _{2 in the} molten metal
A plurality of large diameters are provided at positions below the upper surface level of the molten metal so that the gas does not burn but comes out of the molten metal in an unburned state and the unburned O ₂ gas performs secondary combustion in the slag bath. each of the O ₂ gas to blowing a mixed gas of other species gas other than O _2, such as N ₂ gas or air into the furnace, the furnace top or the furnace outlet of the tuyere and a plurality of small-diameter tuyeres of CO in gas
When the metal raw material is melted and refined while the concentration and CO ₂ concentration are analyzed and the pressure in the furnace is decreased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the outlet of the furnace increases, and conversely, in the furnace. By controlling the above O ₂ gas flow rate, other gas flow rate, and furnace pressure by utilizing the relationship that (CO ₂ / (CO + CO ₂ )) in the furnace upper part or furnace outlet gas decreases with increasing pressure , Upper part of furnace or furnace outlet gas (CO ₂
/ (CO + CO ₂ )) is adjustable, which is a metal refining method. 13. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O _2.
In the metal refining method of combusting with 2 gas to obtain heat and generating CO gas, further burning the CO gas with O ₂ gas to generate heat, and melting and refining the metal raw material with the heat. Some O _{2 in the} molten metal
Gas exits from the molten metal in the unburned state without combustion, as the unburnt O ₂ gas makes a secondary combustion within the slag bath, O ₂
A gas other than O ₂ such as N ₂ gas or air is mixed with the gas, and the mixed gas is blown into the furnace from a position below the upper surface level of the molten metal to obtain (O ₂ gas flow rate) / (other gas Flow rate)
If the ratio is reduced, the (CO ₂
/ (CO + CO ₂ )) increases, and conversely (O ₂ gas flow rate)
When the / (other gas flow rate) ratio is increased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas is decreased, and when the metal melt level in the furnace is decreased, the upper part of the furnace or the furnace outlet and relationship of the gas _{(CO 2 / (CO + CO} 2)) is increased, increasing the furnace the molten metal level in the opposite furnace top or the furnace exit gas _{(CO 2 / (CO + CO} 2)) is reduced, the furnace When the internal pressure is decreased, (CO ₂ / (CO + CO ₂ )) in the furnace upper part or the furnace outlet gas is increased, and conversely, when the furnace pressure is increased, (CO ₂ / (CO + CO 2 ₂ )) is used to control the (O ₂ gas flow rate) / (other gas flow rate) ratio, the level of molten metal in the furnace, and the pressure in the furnace. that _{(CO 2 / (CO + CO} 2)) are possible adjustment Metal refining method according to symptoms. 14. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O _2.
In the metal refining method of combusting with 2 gas to obtain heat and generating CO gas, further burning the CO gas with O ₂ gas to generate heat, and melting and refining the metal raw material with the heat. Some O _{2 in the} molten metal
The gas flows out of the molten metal in an unburned state without burning, and the unburned O ₂ gas conducts secondary combustion in the slag bath so that the O ₂ gas flow is centered from a position below the upper level of the molten metal. As a gas flow having a two-layer structure of inner and outer layers having a gas flow of other species other than O ₂ such as N ₂ gas and air on its outer periphery, is blown into the furnace (O
( ₂ gas flow rate) / (other gas flow rate) ratio decreases (CO ₂ / (CO + CO ₂ ))
When the ratio of (O ₂ gas flow rate) / (other type gas flow rate) is increased, (CO ₂ /
(CO + CO ₂ )) decreases, and when the level of the molten metal in the furnace is decreased, the (CO
₂ / (CO + CO ₂ )) increases and conversely the level of molten metal in the furnace increases, the (CO
₂ / (CO + CO ₂ )) decreases, and when the pressure inside the furnace is decreased, (CO ₂ /
(CO + CO ₂ )) increases, and conversely, when the pressure in the furnace is increased, (CO ₂ / (CO + C
O ₂ )) decreases, and (O ₂ gas flow rate)
(CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or in the furnace outlet gas can be adjusted by controlling the / (other gas flow rate) ratio, the level of molten metal in the furnace, and the pressure in the furnace. Metal refining method. 15. A metal raw material, a carbon-containing fuel, a slag-forming agent, and O ₂ gas are introduced into a molten metal to convert carbon of the carbon-containing fuel to O _2.
In the metal refining method of combusting with 2 gas to obtain heat and generating CO gas, further burning the CO gas with O ₂ gas to generate heat, and melting and refining the metal raw material with the heat. Some O _{2 in the} molten metal
A plurality of large diameters are provided at positions below the upper surface level of the molten metal so that the gas does not burn but comes out of the molten metal in an unburned state and the unburned O ₂ gas performs secondary combustion in the slag bath. each of the O ₂ gas to blowing a mixed gas of other species gas other than O _2, such as N ₂ gas or air into the furnace, the furnace top or the furnace outlet of the tuyere and a plurality of small-diameter tuyeres of CO in gas
When the metal raw material is melted and refined while the concentration and CO ₂ concentration are analyzed and the level of the molten metal in the furnace is decreased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or in the furnace outlet gas increases, and conversely When the level of molten metal in the furnace is increased, (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the outlet gas of the furnace is decreased, and when the pressure in the furnace is decreased, (CO ₂ of the upper part of the furnace or outlet gas of the furnace is decreased. / (CO + CO ₂ )) increases,
On the contrary, by utilizing the relationship that (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the outlet of the furnace decreases when the pressure in the furnace increases, the above-mentioned O ₂ gas flow rate, other species gas flow rate and furnace molten metal A metal refining method characterized in that (CO ₂ / (CO + CO ₂ )) in the upper part of the furnace or the gas at the furnace outlet can be adjusted by controlling the level and the pressure in the furnace.