Ultra-high oxygen enrichment low carbon smelting method

Abstract

There is provided an ultra-high oxygen enrichment type low carbon smelting method, which includes a charging step and a blast furnace smelting step, in which the blast furnace oxygen enrichment rate is 40% to 50%, the oxygen enrichment rate of the hot stove portion reaches 15 to 20%, the air temperature is in the range of 900 to 1000°C, and for the portion that is insufficient, cold oxygen is blown in from the blowing port, and pulverized coal, highly reducing coal gas, and coke oven gas are blown in from the blowing port to maintain the theoretical combustion temperature at the blowing port in the range of 2350 to 2500°C, and during that period, the blowing coal ratio is 0.3 to 0.35 kg / m of coke oven gas. 3 or the coke rate is reduced to 0.28-0.3 kg / m of decarbonized coal gas. 3 By lowering the replacement rate to 210 kg / t or less at the high oxidation enrichment stage in the blast furnace, the problem of "cold at the top and hot at the bottom" that occurs is solved, and the goal of reducing coke consumption is achieved.

Description

[Technical field]

[0001] The present invention relates to the technical field of blast furnace ironmaking, and more particularly to an ultra-high oxygen enrichment type low carbon smelting method. [Background technology]

[0002] 70% of the energy consumption in the steel industry is generated in the steelmaking process, so reducing carbon consumption in the steelmaking process is the main way to reduce coal in the steel industry. At present, reducing carbon emissions is a technical bottleneck in the development of blast furnace technology. The allowable space for further reducing fuel consumption of molten iron is very limited, and there is a limit to enlarging the size of blast furnaces and improving production efficiency. Currently, the fuel consumption for blast furnace smelting of molten iron is often about 550 kg per ton of molten iron, but against the background of China's progress in low-carbonization and decarbonization, it seems that there is still a long way to go to achieve the goal of reducing carbon emissions from traditional blast furnaces.

[0003] The traditional blast furnace ironmaking process is mainly as follows. Sintered ore, pellets, coke, and solvent are mixed in a certain ratio to form a charge, and the charge is charged into the furnace from the top of the furnace, and then hot air, oxygen gas, and pulverized coal are blown in from the blast furnace blast port to humidify it. When the charge moves in contact with the hot air in the blast furnace, heat conduction and oxidation-reduction reactions occur, generating coal gas. The coal gas moves upward and leaves the blast furnace through the riser. The blast furnace raw materials melt during the reaction process and drip as molten iron and slag, and the liquid slag is discharged from the blast furnace through the pig-hole. In the traditional blast furnace, when the temperature inside the furnace is highly oxygen-enriched, the temperature inside the furnace is distributed so that it is "cold at the top and hot at the bottom", which makes it difficult to develop the smelting process. At the same time, the iron elements in the furnace depend on direct reduction by carbon, accounting for about 35% to 40%, so the consumption of coke is large. Summary of the Invention

[0004] The present invention aims to provide an ultra-high oxygen-enriched low-carbon smelting method that can reduce the proportion of direct reduction and increase the proportion of indirect reduction to reduce the amount of coke consumed in the process, in order to solve the problem of the temperature distribution in the furnace being "cold at the top and hot at the bottom" as described in the background art above.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] An ultra-high oxygen enrichment type low carbon smelting method, A charging process (S1) in which an ore charge having a composition of 60-80% sinter, 20-40% pellets, and 0-5% raw ore and coke is charged into a blast furnace in layers; The amount of blast furnace injection per ton of molten iron is 570 to 690 m 3 / t, the blast temperature is controlled to be within the range of 900 to 1000°C, and pure oxygen is blown into the blast furnace, thereby forming an ultra-high oxygen-enriched smelting operation state in the blast furnace. Here, oxygen is enriched by 15 to 20% before the hot stove, but cold oxygen is blown in from the blast port to make up for the insufficient portion, and pulverized coal, highly reducing coal gas, and coke oven gas are blown in from the blast port to maintain the theoretical combustion temperature at the blast port within the range of 2350 to 2500°C. During that period, the injection coal ratio is set to 0.3 to 0.35 kg / m of the coke oven gas. 3 or the coke rate is reduced to 0.28-0.3 kg / m of decarbonized coal gas. 3 and a blast furnace smelting process (S2) for reducing the replacement rate to 210 kg / t or less.

[0007] The pure oxygen injected into the blast furnace is divided into two parts, one of which is oxygen gas heated by the hot stove, accounting for 15-20% of the total amount of gas injected. The furnace temperature is 900-1000°C, and the total oxygen content of the oxygen injected into the furnace is 40-50%, while the remaining part of the oxygen gas is cold oxygen. Highly reducing coal gas is blast furnace coal gas from which CO2 has been removed, and its composition is CO: 65-75%, H2: 10-18%, N2: 6-15%, others: 5-12%. Since the proportion of CO2 accounts for the majority of the blast furnace coal gas, after the CO2 is removed, the proportion of reducing gases such as CO and H2 is significantly increased, and the amount of oxygen injected per ton of molten iron is 200-300m 3 / t, and the amount of coke oven gas injected per ton of molten iron is 210-230m 3 / t.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0009] When the blast furnace oxygen enrichment rate is 40-50%, the intensity of blast furnace smelting is enhanced and the production rate is increased by 20%. Moreover, since the hot stove oxygen enrichment rate reaches 15-20%, it is equivalent to the oxygen gas in that part being fed into the furnace at a temperature of 900-1000°C, and the heat brought by oxygen enrichment is increased, which can effectively reduce the carbon consumption in the blast furnace. The highly reducing coal gas and coke oven gas are blown in from the blast port, which can participate in the reduction reaction in the furnace, increase the heat value of the coal gas, and strengthen the preheating and reduction reaction of the charge in the upper part, so as to prevent the "top from being cold and the bottom from being hot". In addition, the highly reducing coal gas is blown in from the blast port, and at the same time, the theoretical combustion temperature at the blast port, which is highly oxygen-enriched, can be adjusted, ensuring that the process in the furnace is carried out smoothly. Moreover, coke oven gas is mainly composed of hydrogen gas, has a small molecular weight, has excellent air permeability, and is more likely to undergo a reduction reaction with iron oxide than CO, so the degree of indirect reduction is increased and the consumption of coke can be reduced. Some highly reducing coal gas and coke oven gas can be burned as a heat source to release heat, thereby achieving the goal of reducing the consumption of coke. Here, the overall consumption of coke can be reduced by 10 to 15%. Furthermore, since a large amount of highly reducing coal gas and coke oven gas was blown in from the blast port, the indirect reduction in the upper part of the blast furnace was sufficiently performed, and the carbon consumption for the indirect reduction in the lower part of the blast furnace was significantly reduced. As a result, the goal of reducing the carbon emission from the blast furnace and reducing the fuel ratio was achieved, and in the working conditions of high oxygen enrichment smelting at 50%, the production volume from the blast furnace was increased by 20% and the overall carbon consumption was reduced by 15%. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The following clearly and completely describes the technical solutions of the embodiments of the present invention. It is obvious that the described embodiments are only some of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without any creative efforts are all within the protection scope of the present invention.

[0011] The present invention provides the following technical solutions:

[0012] In the ultra-high oxygen enrichment low carbon smelting method, A charging process (S1) in which an ore charge having a composition of sinter: 60-80%, pellets: 20-40%, and raw ore: 0-5% is raised to the top of the furnace and charged, and the depth of the charge line is controlled to be 1.1-1.6 m; Blast furnace injection volume is 500-600m 3 / min, and the air temperature is controlled to be within the range of 900-1000°C. Here, oxygen enrichment is gradually increased by 15-20% before the hot stove, so that the total oxygen enrichment rate is about 40-50%. After the oxygen enrichment of the hot stove reaches the standard, cold oxygen is blown in from the blowing port to fill the gap, and pulverized coal and coke oven gas (0-250m) are blown in from the blowing port. 3 By injecting 10 ... 3 / t) is increased synchronously, so that the theoretical combustion temperature at the blast outlet is in the range of 2250-2350°C, and the amount of coal gas in the furnace is 1200-1400m 3 / t, and during that period, the injection coal rate was maintained at 0.3 to 0.55 kg / m 3 or the coke rate is reduced to 0.25-0.5 kg / m 3 and a blast furnace smelting process (S2) for reducing the replacement rate of the sintered material.

[0013] The injection of highly reducing coal gas allows the theoretical combustion temperature at the blast outlet to be adjusted so that the temperature at the bottom of the furnace body is not too high. The purpose of the injection of coke oven gas is to allow the coke oven gas to participate in the reduction reaction of iron, thereby reducing the consumption of coke that directly reduces iron. Since the coke oven gas contains a large amount of CO, it may be used to react with iron ore instead of some of the coke.

[0014] In the case of oxygen enrichment, oxygen enrichment in front of the hot stove should be increased first. This is equivalent to oxygen gas in that area being fed into the furnace at a temperature of 900-1000°C or higher, and the amount of heat brought about by the blowing increases, effectively reducing the carbon consumption in the blast furnace process. After oxygen enrichment in front of the hot stove reaches 20%, cold oxygen is blown in from the blower.

[0015] [Example] The control parameters of the conventional blast furnace smelting process are as follows:

[0016] [Table 1] The blast furnace economic and technical indicators in the conventional smelting method are as follows:

[0017] [Table 2] The blast furnace control parameters when the method according to the invention is used are as follows:

[0018] [Table 3] The blast furnace economic and technical indicators controlled by the method according to the present invention are as follows:

[0019] [Table 4] A comparison of the economic and technical indicators of the conventional blast furnace control method and the blast furnace economic and technical indicators controlled by the method of the present invention revealed that, when the method of the present invention is used, when highly reducing coal gas or coke oven gas is blown in from the blast outlet of the blast furnace, the blown in coal gas immediately comes into contact with the charge in the upper part of the blast furnace, causing a reduction reaction, thereby strengthening the indirect reduction reaction in the furnace, and effectively reducing the fuel consumption in the blast furnace smelting process; and, by enriching oxygen in the blast furnace, the smelting is strengthened, and when the coke rate and fuel rate in the blast furnace are significantly reduced, the production amount of molten iron from the blast furnace is also increased, that is, even when the fuel is reduced, the production amount of molten iron is slightly higher than that of the conventional blast furnace ironmaking method.

[0020] It should be noted that, in this specification, the terms "comprises," "including," or other variations are intended to cover the non-exclusive "comprises," whereby a process, method, article, or device that includes a set of elements includes not only those elements, but also other elements not expressly listed or inherent elements of such process, method, article, or device. In the absence of too many limitations, an element limited by the phrase "comprises a ..." does not exclude the presence of other similar elements in the process, method, article, or device that includes said element.

[0021] The above description is only for illustrating the technical solution of the present invention, and is not intended to be limiting. Any other amendments or equivalent replacements to the technical solution of the present invention made by those skilled in the art without departing from the spirit and scope of the technical solution of the present invention should be within the scope of the claims.

Claims

1. An ultra-high oxygen enrichment type low carbon smelting method including a charging process and a blast furnace smelting process, A charging step (S1) of charging an ore charge having a composition of 60 to 80% sintered ore, 20 to 40% pellets, and 0 to 5% raw ore and coke into a blast furnace in layers; The amount of blast furnace injection per ton of molten iron is 570 to 690 m ３ / t, the blast temperature is controlled to be within the range of 900 to 1000°C, and pure oxygen is blown into the blast furnace, thereby forming an ultra-high oxygen-enriched smelting operation state in the blast furnace. Here, oxygen is enriched by 15 to 20% before the hot stove, but cold oxygen is blown in from the blast port to make up for the insufficient portion, and pulverized coal, highly reducing coal gas, and coke oven gas are blown in from the blast port to maintain the theoretical combustion temperature at the blast port within the range of 2350 to 2500°C. During that period, the injection coal ratio is set to 0.3 to 0.35 kg / m of the coke oven gas. ３ or the coke rate is reduced to 0.28-0.3 kg / m of decarbonized coal gas. ３ A blast furnace smelting step (S2) of reducing the replacement rate to 210 kg / t or less; The ultra-high oxygen enrichment type low carbon smelting method is characterized by the above.

2. 2. The ultra-high oxygen enrichment type low carbon smelting method according to claim 1, wherein the oxygen enrichment rate in the total amount of injection reaches 40% to 50%.

3. The ultra-high oxygen enrichment low carbon smelting method according to claim 1, characterized in that the 15-20% oxygen enrichment is heated to a temperature of 900-1000 ° C. through a hot stove heating system.

4. The amount of the highly reducing coal gas injected per ton of molten iron is 200 to 300 m ３ 2. The ultra-high oxygen enrichment type low carbon smelting method according to claim 1, characterized in that:

5. The amount of coke oven gas injected per ton of molten iron is 210 to 230 m ３ 2. The ultra-high oxygen enrichment type low carbon smelting method according to claim 1, characterized in that:

6. The composition of the highly reducing coal gas is: CO: 65-75%, H ２ : 10-18%, N ２ : 6-15%, others: 5-12%, 2. The ultra-high oxygen enrichment type low carbon smelting method according to claim 1 .

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