Ironmaking methods

Abstract

To provide a steelmaking method that emits virtually no carbon. [Solution] The ironmaking method comprises a step of generating a thermite reaction by heating an aluminum-containing lump and iron ore.

Description

Technical Field

[0001] Embodiments of the present invention relate to an ironmaking method.

Background Art

[0002] In recent years, in order to address global environmental problems, the realization of carbon neutrality has been desired. In ironmaking by blast furnace, pig iron is obtained by reacting iron ore and coke, but a large amount of carbon dioxide is emitted as a byproduct. Under such circumstances, methods for reducing iron ore with hydrogen have been studied.

[0003] However, since the reduction of iron oxide with hydrogen is an endothermic reaction, in order to secure a heat source, an indirect reduction reaction using coke has to be used in combination. For this reason, there is still a problem that carbon dioxide is emitted and carbon neutrality cannot be achieved.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Non-Patent Documents

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] An objective of the embodiments of the present invention is to provide a steelmaking method that substantially emits no carbon. [Means for solving the problem]

[0007] An embodiment of the present invention provides a method for ironmaking that includes a step of generating a thermite reaction by heating an aluminum-containing lump and iron ore. [Effects of the Invention]

[0008] According to embodiments of the present invention, a steelmaking method that substantially emits no carbon can be realized. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 shows a steelmaking method according to an embodiment. [Modes for carrying out the invention]

[0010] Figure 1 shows a steelmaking method according to an embodiment. As shown in Figure 1, in the ironmaking method according to this embodiment, a furnace 100 is prepared. The furnace 100 is, for example, a blast furnace. The shape of the furnace 100 is generally that of a cylindrical tower.

[0011] A gas riser pipe 101 is provided on the top surface of the furnace 100 and is connected to the inside of the furnace 100. A raw material charging pipe 102 is provided on the upper side of the furnace 100. The lower end of the raw material charging pipe 102 is located in the upper part of the inside of the furnace 100. A swirling chute 103 is provided inside the furnace 100. By swirling, the swirling chute 103 evenly distributes the raw material discharged from the raw material charging pipe 102 into the furnace 100.

[0012] A raw material inlet 104 and a blower nozzle 105 are provided at the lower part of the side of the furnace 100, with the raw material inlet 104 communicating with the blower nozzle 105. The blower nozzle 105 communicates with the inside of the furnace 100. Below the blower nozzle 105 on the side of the furnace 100, a slag outlet 106 is provided, which communicates with the inside of the furnace 100. At the very bottom of the side of the furnace 100, a tapping nozzle 107 is provided, which communicates with the inside of the furnace 100.

[0013] Inside the furnace 100, a large number of ceramic pellets 110 are arranged at a height equal to or greater than that of the air tuyere 105 to form a ceramic granule layer 111 consisting of a large number of pellets 110. It is preferable that the ceramic granule layer 111 covers at least a portion of the air tuyere 105. It is preferable that the specific gravity of the pellets 110 is lower than the specific gravity of aluminum (approximately 2.7).

[0014] For example, pellet 110 is made of a porous material, such as a porous material containing calcium oxide, zirconium oxide, or boron nitride. In this case, the specific gravity of pellet 110 is, for example, about 1.8 to 2.5. The diameter of pellet 110 is, for example, about 1 to 2 cm. The melting point of calcium oxide is about 2613°C, the melting point of zirconium oxide is about 2715°C, and the melting point of boron nitride is about 2700°C.

[0015] Alternatively, the ceramic granule layer 111 may be formed using granular or lump-shaped ceramic material instead of pellets 110. Furthermore, before the furnace 100 is first put into operation, granular iron material or some kind of sacrificial material may be placed below the ceramic granule layer 111 to support it.

[0016] Above the ceramic particle layer 111 in the furnace 100, as raw materials for ironmaking, iron ore 201 and a mass 202 containing aluminum are arranged. The mass 202 containing aluminum (hereinafter simply referred to as "aluminum mass 202") preferably does not contain copper. The aluminum mass 202 is, for example, obtained by pulverizing used aluminum cans with the paint peeled off or used aluminum building materials with the paint peeled off. The method of peeling the paint is, for example, mechanical treatment such as high-pressure water spraying or chemical treatment with chemicals. Note that the aluminum cans may be used without being pulverized. The material of the aluminum cans is, for example, A3003 according to JIS standards. The material of the aluminum building materials is, for example, A1080 or A1100 according to JIS standards.

[0017] Specifically, the iron ore 201 and the aluminum mass 202 are charged into the furnace 100 through the raw material charging pipe 102. The iron ore 201 and the aluminum mass 202 discharged from the raw material charging pipe 102 are evenly distributed by the swivel chute 103 and deposited in the furnace 100 to form a mixed layer 211 containing the iron ore 201 and the aluminum mass 202.

[0018] Next, only the iron ore 201 is charged into the furnace 100 through the raw material charging pipe 102. The iron ore 201 discharged from the raw material charging pipe 102 is evenly distributed by the swivel chute 103 and deposited in the furnace 100 to form an iron ore layer 212 containing only the iron ore 201. By repeating this, in the furnace 100, the mixed layer 211 and the iron ore layer 212 are alternately laminated.

[0019] In this state, heated hydrogen gas 220 is supplied into the furnace 100 from the tuyere 105. The temperature of the hydrogen gas 220 is preferably 600°C or higher, more preferably 700°C or higher, and is, for example, about 900°C. The hydrogen gas 220 introduced from the tuyere 105 rises in the furnace 100, reaches the lowermost mixed layer 211, and heats the iron ore 201 and the aluminum mass 202.

[0020] As a result, a thermite reaction occurs between the iron oxide contained in the iron ore 201 and the aluminum contained in the aluminum mass 202. Specifically, the reactions represented by the following chemical reaction formulas (1) and (2) proceed.

[0021] Fe2O3+2Al → 2Fe+Al2O3+830kJ (1) 3Fe3O4+8Al → 9Fe+4Al2O3+3237kJ (2)

[0022] As a result, elemental iron (Fe) 230 and aluminum oxide (Al2O3) are produced. Since this reaction is an exothermic reaction, the hydrogen gas 220 is further heated. Thereby, the iron ore 201 in the iron ore layer 212 disposed one layer above the lowermost mixed layer 211 is heated.

[0023] As a result, a hydrogen reduction reaction occurs between the iron oxide contained in the iron ore 201 and the hydrogen gas 220. Specifically, the reactions represented by the following chemical reaction formulas (3) and (4) proceed.

[0024] Fe2O3+3H2→ 2Fe+3H2O↑-100~300kJ (3) Fe3O4+4H2→ 3Fe+4H2O↑-100~300kJ (4)

[0025] As a result, elemental iron (Fe) 230 and water vapor (H2O) are produced. This reaction is an endothermic reaction. Also, since the generated water vapor is oxidizing, it oxidizes the surface of the aluminum mass 202 in the upper mixed layer 211 as the water vapor rises in the furnace 100. Thereby, the thermite reaction is suppressed in the upper mixed layer 211, and a rapid temperature rise in the upper part of the furnace 100 is suppressed.

[0026] In this way, hydrogen gas 220 rises within the furnace 100, sequentially heating the alternately stacked mixed layers 211 and iron ore layers 212, and the thermite reaction and hydrogen reduction reaction proceed. As described above, the thermite reaction is an exothermic reaction and the hydrogen reduction reaction is an endothermic reaction, so the ratio of the thermite reaction to the hydrogen reduction reaction can be selected by adjusting the ratio of the input amounts of iron ore 201, aluminum ingots 202, and hydrogen gas 220. As a result, the temperature inside the furnace 100 can be controlled and the above reactions can be continued.

[0027] In one example, the temperature near the bottom surface of the ceramic granule layer 111 is controlled to be around 900°C, the temperature near the bottom surface of the lowest mixed layer 211 is controlled to be around 2000-2500°C, the temperature near the center of the furnace 100 in the height direction is controlled to be around 1000-1500°C, and the temperature near the top surface of the uppermost iron ore layer 212 is controlled to be around 100-500°C.

[0028] As the iron ore 201 and aluminum ingots 202 are consumed by the thermite reaction and hydrogen reduction reaction, the upper layers of iron ore 201 and aluminum ingots 202 gradually descend within the furnace 100. If the surface of the aluminum ingots 202 that have descended from above is oxidized and the thermite reaction has stopped or slowed down, aluminum powder 203 may be introduced through the raw material inlet 104. The size of the aluminum powder should be such that it can be introduced into the furnace 100 by hydrogen gas 220. Since the raw material inlet 104 is connected to the furnace 100 after joining with the air blower nozzle 105, the aluminum powder 203 introduced into the furnace 100 is covered by hydrogen gas 220 and reaches the mixing layer 211 in an isolated state from the oxidizing atmosphere, contributing to the thermite reaction. In this way, the aluminum powder 203 functions as a reaction accelerator.

[0029] Alternatively, the temperature of the supplied hydrogen gas 220 may be increased. For example, by raising the temperature of the hydrogen gas 220 above the melting point of aluminum, 660°C, the aluminum ingot 202 can be melted, destroying the oxide film on the surface of the aluminum ingot 202. This also promotes the thermite reaction.

[0030] Conversely, if the thermite reaction becomes excessive and the temperature rises too high, oxygen gas or an oxidizing substance may be introduced through the raw material inlet 104. This oxidizes the surface of the aluminum ingot 202 and controls the thermite reaction. The thermite reaction can also be controlled by adjusting the amount of aluminum powder 203 added and the mixing ratio in the mixing layer 211.

[0031] Since the iron 230 produced by the thermite reaction and hydrogen reduction reaction described above is a liquid, it falls through the gaps between the unreacted iron ore 201 and aluminum chunks 202, passes through the gaps in the pellets 110 and the ceramic granule layer 111, and accumulates below the ceramic granule layer 111.

[0032] Furthermore, unreacted liquid aluminum (Al) 240 also falls to the bottom of the ceramic granule layer 111 and accumulates through the gaps between the unreacted iron ore 201 and aluminum chunks 202, and through the gaps between the pellets 110.

[0033] Furthermore, slag 250 is produced as a byproduct of each of the above-mentioned reactions. In addition to aluminum oxide (Al2O3) produced by the thermite reaction described above, slag 250 contains impurities contained in the iron ore 201, impurities contained in the aluminum ingot 202 and aluminum powder 203, and substances derived from the heat-resistant bricks that make up the inner wall of the furnace 100. For example, slag 250 contains Al2O3, FeO, MgO, CaO, MnO, SiO2, FeO, C, etc.

[0034] The specific gravity of iron 230 is approximately 7.8, the specific gravity of slag 250 is about 3.1 to 3.2, the specific gravity of aluminum 240 is approximately 2.7, and the specific gravity of pellets 110 is, for example, 1.8 to 2.5. Therefore, at the bottom of the furnace 100, the materials are layered from bottom to top in the following order: liquid iron 230, slag 250, liquid aluminum 240, and pellets 110. In other words, the solid pellets 110 float on the liquid aluminum 240.

[0035] Once the thermite reaction and hydrogen reduction reaction described above have progressed to a certain extent, liquid iron (pig iron) 230 is recovered through the tap port 107. Liquid aluminum 240 and slag 250 are discharged through the slag port 106. Furthermore, various impurity gases are discharged from the gas riser pipe 101, in addition to the water vapor (H2O) and unreacted hydrogen gas (H2) 220 generated by the hydrogen reduction reaction described above. These impurity gases include, for example, oxygen (O2), carbon monoxide (CO), and hydrocarbons (C2). x H y It contains trace amounts of ).

[0036] When the thermite reaction and hydrogen reduction reaction proceed and the amount of iron ore 201 and aluminum ingots 202 decreases, either only iron ore 201, or both iron ore 201 and aluminum ingots 202, are introduced into the furnace 100 via the raw material charging pipe 102. This allows the ironmaking process to continue.

[0037] Next, the effects of this embodiment will be described. According to this embodiment, iron 230 can be refined from iron ore 201 by inducing a thermite reaction using an aluminum ingot 202. Since the thermite reaction is an exothermic reaction, there is no need to use an indirect reduction reaction using coke in combination. As a result, a steelmaking method that substantially emits no carbon can be realized, achieving carbon neutrality.

[0038] Furthermore, because coke is not used, the refined iron-230 has low concentrations of impurities such as phosphorus (P) and sulfur (S). This allows for the omission or simplification of secondary refining processes.

[0039] Furthermore, in this embodiment, heated hydrogen gas 220 is supplied into the furnace 100. This allows a hydrogen reduction reaction to occur in addition to the thermite reaction. Since the hydrogen reduction reaction is an endothermic reaction, the temperature inside the furnace 100 can be arbitrarily controlled by combining the thermite reaction and the hydrogen reduction reaction. Also, because the heat generated by the thermite reaction is utilized, the temperature of the hydrogen gas 220 can be lowered compared to when only the hydrogen reduction reaction is performed. As a result, steelmaking costs can be reduced.

[0040] Furthermore, in this embodiment, in addition to supplying iron ore 201 and aluminum ingots 202 from above the furnace 100 via the raw material charging pipe 102, aluminum powder 203 can be supplied from below the furnace 100 via the raw material inlet 104 as needed. This allows the reaction rate of the thermite reaction to be controlled by using the aluminum powder 203 as a reaction accelerator.

[0041] Furthermore, in this embodiment, a ceramic granule layer 111 consisting of multiple pellets 110 is provided inside the furnace 100 and is positioned at a height equal to or greater than that of the air blower nozzle 105. This allows the hydrogen gas 220 introduced from the air blower nozzle 105 to spread throughout the furnace 100. In addition, the refined iron 230 can fall through the gaps between the pellets 110, separating it from the unreacted iron ore 201 and aluminum lumps 202, and allowing it to accumulate at the bottom of the furnace 100. As a result, when the iron 230 is recovered from the tap 107, the purity of the iron 230 is high.

[0042] Furthermore, by forming the pellets 110 from a porous material, the specific gravity of the pellets 110 can be made lower than that of aluminum. As a result, even if unreacted liquid aluminum 240 falls to the bottom of the furnace 100, the pellets 110 float on the aluminum 240, thus maintaining the position of the ceramic granule layer 111. In addition, the liquid aluminum 240 is located above the ceramic granule layer 111, so as not to obstruct the flow of hydrogen gas 220.

[0043] Furthermore, in this embodiment, a mixed layer 211 containing iron ore 201 and aluminum ingots 202 is alternately layered with an iron ore layer 212 containing only iron ore 201. This makes it easy to adjust the ratio of iron ore 201 to aluminum ingots 202.

[0044] Furthermore, in this embodiment, the aluminum ingot 202 and aluminum powder 203 are made from crushed used aluminum cans or used aluminum building materials with the paint removed. Since such materials are substantially copper-free, high-quality iron can be produced. In addition, since recycled materials and waste materials can be utilized, costs and environmental impact can be reduced.

[0045] The embodiments described above are examples that embody the present invention, and the present invention is not limited to these embodiments. For example, the present invention is also included in the embodiments described above in which some components or processes are added, deleted, or modified. For example, in this embodiment, an example in which a blast furnace is used as furnace 100 is shown, but the present invention is not limited thereto. For example, a shaft furnace or an electric furnace may be used as furnace 100.

[0046] The present invention includes the following embodiments.

[0047] (Note 1) A method for iron production comprising a step of generating a thermite reaction by heating an aluminum-containing lump and iron ore.

[0048] (Note 2) The ironmaking method described in Appendix 1, wherein the heating is performed by supplying hydrogen gas at a temperature of 600°C or higher to a furnace into which the lump and the iron ore have been introduced.

[0049] (Note 3) The ironmaking method according to Appendix 2, wherein powder containing aluminum is supplied through a tuyer in the furnace that supplies hydrogen gas.

[0050] (Note 4) The ironmaking method according to Appendix 2 or 3, wherein a plurality of ceramic pellets are arranged at a height equal to or greater than the tuyere that supplies hydrogen gas in the furnace, and the lump and the iron ore are arranged above the plurality of pellets.

[0051] (Note 5) The steelmaking method described in Appendix 4, wherein the pellets are made of a porous material.

[0052] (Note 6) The aforementioned pellets are made using the ironmaking method described in Appendix 5, wherein the pellets contain calcium oxide, zirconium oxide, or boron nitride.

[0053] (Note 7) A method of iron production according to any one of the appendices 1 to 6, wherein a mixed layer containing the lump and the iron ore and an iron ore layer containing only the iron ore are alternately stacked in a furnace.

[0054] (Note 8) The aforementioned mass is made from crushed used aluminum cans or crushed used aluminum building materials, as described in any one of the appendices 1 to 7. [Explanation of Symbols]

[0055] 100 furnace 101 Gas riser 102 Raw material loading tube 103 Swinging Shoot 104 Raw material input port 105 Air vent nozzle 106 Slag mouth 107 Taphead 110 pellets 111 Ceramic Granules 201 Iron Ore 202 Aluminum ingot 203 Aluminum powder 211 Mixed layer 212 Iron Ore Layer 220 Hydrogen gas 230 Iron 240 Aluminum 250 slag

Claims

1. A method for iron production comprising a step of generating a thermite reaction by heating an aluminum-containing lump and iron ore.

2. The ironmaking method according to claim 1, wherein the heating is performed by supplying hydrogen gas with a temperature of 600°C or higher to a furnace into which the lump and the iron ore have been introduced.

3. The ironmaking method according to claim 2, wherein powder containing aluminum is supplied through a tuyer that supplies hydrogen gas in the furnace.

4. The ironmaking method according to claim 2, wherein a plurality of ceramic pellets are arranged at a height equal to or greater than the tuyere that supplies hydrogen gas in the furnace, and the lump and the iron ore are arranged above the plurality of pellets.

5. The steelmaking method according to claim 4, wherein the pellets are made of a porous material.

6. The ironmaking method according to claim 5, wherein the pellet comprises calcium oxide, zirconium oxide, or boron nitride.

7. The ironmaking method according to claim 1, wherein a mixed layer containing the lump and the iron ore and an iron ore layer containing only the iron ore are alternately stacked in the furnace.

8. The steelmaking method according to claim 1, wherein the mass is made from crushed used aluminum cans or crushed used aluminum building materials.

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