Carbon material for blast furnace and method for producing pig iron

Abstract

To provide a carbonaceous material for a blast furnace and a method for producing pig iron, which can reduce a molten iron desulfurization cost and energy required for molten iron desulfurization.SOLUTION: The carbonaceous material for a blast furnace is used for blowing from a tuyere of the blast furnace and has ≤0.2 mass% total sulfur content, ≥1.0 mass% volatile content, ≤10 mass% ash content and ≥6000 kcal / kg net calorific value.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing blast furnace carbonaceous material and pig iron used for injection into the tuyere of a blast furnace. [Background technology]

[0002] In recent years, the demand for higher purity steel has led to an increasing demand for lower sulfur concentrations in steel. Meanwhile, sulfur input at the molten iron stage is on the rise due to the increasing impurity concentrations in raw materials (iron ore, coal) in the steelmaking process. Under these circumstances, the amount of desulfurization at the molten iron stage increases, leading to an increased consumption of desulfurization agents during the molten iron treatment stage, resulting in higher desulfurization costs. This also increases the amount of desulfurization slag generated and heat loss. Therefore, a reduction in sulfur input in blast furnaces is desired from the perspectives of both cost and production efficiency. Against this background, Patent Document 1 describes a method for blast furnace operation in which pulverized coal is injected from the tuyeres as an auxiliary reducing agent. The method involves pulverizing biomass charcoal obtained by carbonizing biomass to produce a pulverized material, and then injecting the pulverized biomass charcoal and the pulverized coal from the tuyeres. Patent Document 2 also describes a method for semi-carbonizing biomass at temperatures between 250 and 600°C in an inert gas atmosphere, followed by pulverization to produce a pulverized carbonaceous material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-117074 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-57438 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the method described in Patent Document 1 does not specify the sulfur content of biomass dry distillate, and does not contribute to reducing the cost of hot metal desulfurization or the energy required for hot metal desulfurization (CO2 emissions). Furthermore, Patent Document 1 does not specify the detailed conditions that should be met for the auxiliary fuel injected from the blast furnace tuyeres, other than the volatile content. Similarly, the method described in Patent Document 2 does not specify the sulfur content of torrefied biomass, and does not contribute to reducing the cost of hot metal desulfurization or the energy required for hot metal desulfurization.

[0005] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a method for producing carbonaceous material for blast furnaces and pig iron that can reduce the cost of molten iron desulfurization and the energy required for molten iron desulfurization. [Means for solving the problem]

[0006] The carbonaceous material for blast furnaces according to the present invention is a carbonaceous material for blast furnaces used for injection into the tuyere of a blast furnace, and has a total sulfur content of 0.2 mass% or less, a volatile matter content of 1.0 mass% or more, an ash content of 10 mass% or less, and a net calorific value of 6000 kcal / kg or more.

[0007] It is preferable that the combustion start temperature is 550°C or less.

[0008] The pore surface area of ​​pores with a diameter of 0.3 to 1.0 nm measured by CO2 adsorption method is 50 m 2 / g or more.

[0009] It is preferable that the biomass is produced using woody biomass and / or herbaceous biomass as a raw material.

[0010] It is preferable that the material be made from waste plastic.

[0011] A method for producing pig iron according to the present invention includes a step of injecting the blast furnace carbonaceous material according to the present invention into a blast furnace through a tuyere. [Effects of the Invention]

[0012] According to the method for producing carbonaceous material for blast furnaces and pig iron of the present invention, it is possible to reduce the cost of desulfurizing molten iron and the energy required for desulfurizing molten iron. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of a blast furnace to which a carbonaceous material for a blast furnace according to one embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a carbonaceous material for blast furnaces according to one embodiment of the present invention will be described with reference to the drawings.

[0015] [Blast furnace configuration] First, with reference to FIG. 1, the configuration of a blast furnace to which a carbonaceous material for a blast furnace according to one embodiment of the present invention is applied will be described.

[0016] Fig. 1 is a schematic diagram showing the configuration of a blast furnace to which a blast furnace carbonaceous material according to one embodiment of the present invention is applied. As shown in Fig. 1, in a blast furnace 1 to which a blast furnace carbonaceous material according to one embodiment of the present invention is applied, an ore layer 2 containing raw ore materials such as sintered ore, pellets, and lump ore and a coke layer 3 containing coke are alternately layered, and hot air and auxiliary fuel are blown into the blast furnace 1 through tuyeres 4 provided at the bottom of the blast furnace 1 to heat, reduce, and melt the raw ore materials to produce pig iron. However, the blast furnace to which the blast furnace carbonaceous material according to one embodiment of the present invention is applied is not limited to the blast furnace 1 shown in Fig. 1. Products produced using CO2, CO2, H2, and other blast furnace gases recovered from exhaust gas or the like as raw materials may also be blown into the tuyeres and used as reducing agents or raw material heating materials.

[0017] [Charcoal material for blast furnace] Next, a carbonaceous material for blast furnaces according to one embodiment of the present invention will be described in detail.

[0018] The blast furnace carbonaceous material, which is one embodiment of the present invention, is a carbonaceous material injected into the blast furnace 1 from the tuyere 4 as auxiliary fuel, and has a total sulfur content (TS, db) of 0.2 mass% or less, a volatile matter (VM, db) of 1.0 mass% or more, an ash content (Ash, db) of 10 mass% or less, and a net calorific value (Net-CV, db) of 6000 kcal / kg or more. By keeping the total sulfur content at 0.2 mass% or less, the sulfur content in the pig iron is reduced, thereby reducing the energy and cost required for the subsequent desulfurization process. Furthermore, by keeping the volatile matter at 1.0 mass% or more, ignition in the raceway immediately after injection from the tuyere 4 can be ensured. Furthermore, by keeping the ash content at 10 mass% or less and the net calorific value at 6000 kcal / kg or more, the effective calorific value (calorific value up to CO and H) in the blast furnace 1 can be ensured.

[0019] The combustion start temperature of the blast furnace carbonaceous material is preferably 550° C. or less, which further ensures ignition ability in the raceway immediately after being injected from the tuyere 4.

[0020] In addition, the surface area of ​​pores with a diameter of 0.3 to 1.0 nm measured by the CO2 adsorption method in blast furnace carbonaceous materials is 50 m 2 / g or more, thereby ensuring the combustion rate in the raceway immediately after being injected from the tuyere 4.

[0021] Furthermore, blast furnace carbon is preferably produced from woody biomass and / or herbaceous biomass such as sawmill waste, thinned wood, agricultural residue, etc. This can reduce CO2 emissions.

[0022] Furthermore, carbon for blast furnaces can be produced using waste plastics as a raw material, which can reduce CO2 emissions. [Example]

[0023] Table 1 shows examples of the present invention. As a comparative example, coal was used that had, on a dry weight basis (db), fixed carbon (FC) of 74.0 mass%, volatile matter (VM) of 16.5 mass%, ash of 9.5 mass%, and total sulfur (TS) of 0.44 mass%. The net calorific value (Net-CV) of this coal was 7542 kcal / kg, the combustion start temperature was 455°C, and the pore surface area of ​​pores with diameters of 0.3 to 1 nm measured by the CO2 adsorption method was 38 m 2 As an example, a carbonaceous material was used with a dry weight basis (db) of 76.6 mass% fixed carbon (FC), 20.3 mass% volatile matter (VM), 3.1 mass% ash, and 0.01 mass% total sulfur (TS). The net calorific value (Net-CV) of this carbonaceous material was 7314 kcal / kg, the combustion start temperature was 361°C, and the pore surface area of ​​pores with a diameter of 0.3 to 1 nm measured by the CO2 adsorption method was 257 m 2 / g.

[0024] [Table 1]

[0025] Table 2 shows the sulfur concentration in molten pig iron produced using the coal of the comparative example and the carbonaceous material of the example, as well as the CaO-based desulfurization agent consumption rate required for the subsequent hot metal pretreatment. The carbonaceous material of the example reduced the amount of sulfur input to the blast furnace and the S concentration in the molten pig iron compared to the coal of the comparative example. Therefore, the CaO-based desulfurization agent consumption rate required for the hot metal pretreatment was reduced. This confirmed that the use of the carbonaceous material of the example can reduce the sulfur concentration in molten pig iron and reduce the desulfurization agent consumption rate required for the hot metal pretreatment. While the present blast furnace carbonaceous material is used in a conventional blast furnace, the present invention is not limited to this. It may also be injected into the tuyere of a blast furnace that uses a product produced using carbon-containing gas recovered from exhaust gas as a carbon raw material (a so-called carbon recycling blast furnace) as a reducing agent.

[0026] [Table 2]

[0027] Although the present invention has been described above as an embodiment, the present invention is not limited to the descriptions and drawings that form part of the disclosure of the present invention. In other words, other embodiments, examples, and operational techniques that can be made by those skilled in the art based on the present invention are all included in the scope of the present invention. [Explanation of symbols]

[0028] 1 blast furnace 2 Ore Layers 3 Coke layer 4 Tuyere

Claims

1. A blast furnace carbonaceous material used to inject into the tuyere of a blast furnace, Total sulfur content is 0.2 mass% or less, Volatile content is 1.0 mass% or more, Ash content is 10 mass% or less, The net calorific value is 6000 kcal / kg or more. Charcoal material for blast furnaces.

2. The carbonaceous material for blast furnaces according to claim 1, wherein the combustion start temperature is 550°C or less.

3. CO ２ The pore surface area of ​​pores with a diameter of 0.3 to 1.0 nm measured by the adsorption method is 50 m ２ The carbonaceous material for a blast furnace according to claim 1, wherein the carbonaceous material has a Cr content of 0.15 / g or more.

4. The carbonaceous material for blast furnaces according to claim 1, which is produced using woody biomass and / or herbaceous biomass as a raw material.

5. The carbonaceous material for blast furnaces according to claim 1, which is produced using waste plastics as a raw material.

6. A method for producing pig iron, comprising the step of injecting the blast furnace carbonaceous material according to any one of claims 1 to 5 from a tuyere of a blast furnace.

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