An efficient electro-hydrogen conversion reduction smelting apparatus and method

Abstract

This invention discloses an electro-hydrogen high-efficiency conversion reduction smelting apparatus and method, belonging to the field of metallurgical technology. It uses pure hydrogen as a reducing agent and functionally divides pre-reduction and deep reduction into zones to obtain high-purity molten iron. The electro-hydrogen high-efficiency conversion reduction smelting apparatus includes a multi-zone induction furnace, comprising a first zone, a second zone, and a third zone. The second and third zones are located on either side of the first zone, with the second zone situated in the lower middle part of the first zone and directly connected to it. The third zone is connected to the bottom of the first zone via a sliding nozzle. During reduction smelting, the second zone serves as the slag-iron layer melting zone. The first zone is divided from bottom to top into a pre-reduced molten iron layer, a slag-iron layer reduction zone, and a molten slag layer. The slag-iron layer melting zone is connected to the slag-iron layer reduction zone. The third zone is divided from bottom to top into a deep-reduced molten iron layer and a refining slag layer. Using the apparatus of this invention for reduction smelting can yield high-purity molten iron.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to an electro-hydrogen high-efficiency conversion reduction smelting apparatus and method. Background Technology

[0002] Developing hydrogen metallurgy, which replaces carbon with hydrogen, is one of the most effective ways to reduce carbon emissions in the steel industry.

[0003] Current hydrogen metallurgical processes include vertical shaft furnace and fluidized bed direct reduction processes. Vertical shaft furnaces mainly use oxidized pellets as raw materials, which involves a long raw material processing procedure and high energy consumption. Furthermore, neither of these two processes can directly obtain molten iron and requires further melting and separation, which increases equipment investment. Summary of the Invention

[0004] In view of the above, the present invention aims to provide an electro-hydrogen high-efficiency conversion reduction smelting apparatus and method, which uses pure hydrogen as a reducing agent and divides the pre-reduction and deep reduction into functional zones to obtain high-purity molten iron.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] On one hand, the present invention provides an electro-hydrogen high-efficiency conversion reduction smelting device, which includes a multi-zone induction furnace, comprising a first zone, a second zone, and a third zone; the second zone and the third zone are located on both sides of the first zone, the second zone is located in the lower middle part of the first zone, and the second zone is directly connected to the first zone; the third zone is connected to the bottom of the first zone through a sliding nozzle; during reduction smelting, the second zone serves as the slag-iron layer melting zone, the first zone is divided from bottom to top into a pre-reduced molten iron layer, a slag-iron layer reduction zone, and a molten slag layer; the slag-iron layer melting zone is connected to the slag-iron layer reduction zone; the third zone is divided from bottom to top into a deep-reduced molten iron layer and a refining slag layer.

[0007] Furthermore, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a batching system and a spraying system connected to the batching system. After the material is batched in the batching system, it is sprayed to the second zone through the spraying system.

[0008] Furthermore, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a first spray gun, which is located on the side of the second zone and is used to spray hydrogen into the second zone.

[0009] Furthermore, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a second spray gun, which is located on the side of the third zone and is used to spray hydrogen into the third zone.

[0010] Furthermore, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a vacuum granulation chamber, which is located below the third zone.

[0011] Furthermore, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a waste heat recovery system, a high-temperature dust removal device, an oxygen combustion system, and a high-temperature electrolysis device connected in sequence.

[0012] This invention also provides a method for high-efficiency electro-hydrogen conversion and reduction smelting, employing the aforementioned high-efficiency electro-hydrogen conversion and reduction smelting apparatus, comprising:

[0013] Step 1: At the beginning, industrial pure iron or sponge iron is added to the first zone as an induction heating medium and melted to form a pre-reduced molten iron layer;

[0014] Step 2: A slag-iron mixture layer is formed above the pre-reduced molten iron layer; the slag-iron mixture layer serves as the slag-iron layer reduction zone during continuous production.

[0015] Step 3: The mixture of iron concentrate powder and quicklime powder is added to the second zone through a spraying system. The spraying system uses oxygen as the conveying medium for the mixture. The hydrogen gas generated by the high-temperature electrolysis device is injected into the second zone from the first spray gun and then combusts and releases heat, providing heat for the melting of the material. At the same time, the molten material is conveyed to the slag-iron layer reduction zone.

[0016] Step 4: The molten material enters the slag-iron layer reduction zone and undergoes a molten pre-reduction reaction with the molten iron brought by the "spring" below to form low-valence iron oxides. At the same time, it is reduced to metallic iron by high-temperature hydrogen and slag-iron separation occurs. The molten slag floats to the molten slag layer and the molten iron sinks to the pre-reduced molten iron layer.

[0017] Step 5: Open the sliding gate, and the molten iron in the pre-reduced iron layer enters the third zone. After the molten iron layer in the third zone reaches the specified height, close the sliding gate and carry out deep reduction smelting. After deep reduction smelting, the oxygen and sulfur content in the molten iron is controlled below 10 ppm.

[0018] Furthermore, in step 4, the reducing gas is first cooled by waste heat recovery to meet the tolerance temperature of the high-temperature dust removal device. The mixture of hydrogen and water vapor obtained from dust removal is then heated by oxygen combustion and finally electrolyzed to produce hydrogen.

[0019] Furthermore, it also includes:

[0020] Step 6: After deep reduction, the molten iron enters the vacuum granulation chamber and is dispersed into fine molten iron particles by the granulator. By greatly increasing the surface area of ​​the molten iron, gaseous impurities in the molten iron are removed.

[0021] Furthermore, in step 3, the binary basicity of the iron concentrate powder and quicklime powder is controlled to be 3.0 to 3.5.

[0022] Furthermore, in step 4, the FeO content in the slag is controlled at 5% to 8% during the reduction process.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] a) The electro-hydrogen high-efficiency conversion reduction smelting device of the present invention adopts a unique multi-zone induction furnace as the reduction smelting device. During implementation, the material is pre-melted in the slag-iron layer melting zone before entering the slag-iron layer reduction zone, reducing heat loss and melting time in the slag-iron layer reduction zone and improving reduction rate and efficiency; the slag-iron layer melting zone forms an independent strong oxidizing atmosphere, improving dephosphorization efficiency. After melting, the material enters the slag-iron layer reduction zone, where the molten iron undergoes molten reduction and desulfurization reactions, and slag-iron separation occurs. The molten slag floats into the slag layer, while the molten iron sinks into the pre-reduced molten iron layer; the pre-reduced molten iron enters the third zone through a "siphon" effect for deep reduction smelting, deeply removing oxygen and sulfur from the molten iron. The second and third zones are connected through the "siphon" principle, realizing integrated reduction smelting.

[0025] b) In the electro-hydrogen high-efficiency conversion reduction smelting device of the present invention, the induction furnace is divided into a melting zone and a reduction zone by eccentric injection feeding. The melting zone directly heats the material by hydrogen combustion, which improves the heating efficiency and melting rate of the material. At the same time, oxygen plays the role of powder conveying and hydrogen plays the role of melt conveying.

[0026] c) The method of this invention achieves precise control over the atmosphere transition from oxidizing to reducing by functionally dividing the slag-iron layer melting zone, slag-iron layer reduction zone, and deep reduction zone. This enables graded and deep removal of phosphorus, sulfur, and oxygen, increasing the removal limits of impurity components. It allows for zoned dephosphorization and desulfurization, improving processing efficiency and molten iron quality, resulting in high-purity molten iron.

[0027] d) The method of this invention uses vacuum granulation instead of conventional argon blowing for deep removal of hydrogen from molten iron, avoiding the use of argon and the drop in molten iron temperature. It also further promotes the reaction between oxygen and hydrogen in the molten iron, while simultaneously promoting hydrogen overflow. This further improves the purity of the molten iron particles, ensuring that the oxygen content in the molten iron is reduced to below 5 ppm and the hydrogen content to below 1 ppm.

[0028] e) The method of the present invention first cools the reducing gas to meet the tolerance temperature of the high-temperature dust collector, and then raises the temperature to control the electrolysis temperature of the reducing gas, ensuring that the system electrolysis efficiency can reach more than 43%, reducing the energy consumption of electrolytic hydrogen production, while directly obtaining high-temperature hydrogen that meets the reduction requirements, avoiding the use of hydrogen heating devices, and ensuring the safety of each piece of equipment.

[0029] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description, claims, and drawings. Attached Figure Description

[0030] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0031] Figure 1 This is a schematic diagram of the electro-hydrogen high-efficiency conversion reduction smelting apparatus of the present invention;

[0032] Figure 2 This is a schematic diagram of the electro-hydrogen high-efficiency conversion reduction smelting method of the present invention.

[0033] Figure Labels

[0034] 1-First zone, 2-Second zone, 3-Third zone, 4-Sliding nozzle, 5-Batching system, 6-Pulse injection system, 7-Vacuum granulation chamber, 8-Waste heat recovery system, 9-High temperature dust removal device, 10-Oxygen combustion system, 11-High temperature electrolysis device, 12-Slag outlet. Detailed Implementation

[0035] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of the present invention and, together with the embodiments of the present invention, serve to illustrate the principles of the present invention.

[0036] This invention provides an efficient electro-hydrogen conversion reduction smelting apparatus, comprising a multi-zone induction furnace, which includes a first zone 1, a second zone 2, and a third zone 3; the second zone 2 and the third zone 3 are located on both sides of the first zone 1, with the second zone 2 located in the lower middle part of the first zone 1 and directly connected to the first zone 1; the third zone 3 is connected to the bottom of the first zone 1 through a sliding nozzle 4; during reduction smelting, the second zone 2 serves as the slag-iron layer melting zone, and the first zone 1 is divided from bottom to top into a pre-reduced molten iron layer, a slag-iron layer reduction zone, and a molten slag layer; the slag-iron layer melting zone is connected to the slag-iron layer reduction zone; the third zone 3 is divided from bottom to top into a deep-reduced molten iron layer and a refining slag layer.

[0037] Specifically, the first zone 1 can be cylindrical.

[0038] Specifically, the upper part of Zone 1 is equipped with a slag outlet 12.

[0039] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a batching system 5 and a blowing system 6 connected to the batching system 5. After the material is batched in the batching system 5, it is blown into the second zone 2 by the blowing system 6.

[0040] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a first spray gun, which is located on the side of the second zone 2 and is used to spray hydrogen into the second zone 2.

[0041] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a second spray gun, which is located on the side of the third zone 3 and is used to spray hydrogen into the third zone 3.

[0042] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a vacuum granulation chamber 7, which is located below the third zone 3.

[0043] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a waste heat recovery system 8, a high-temperature dust removal device 9, an oxygen combustion system 10, and a high-temperature electrolysis device 11 connected in sequence.

[0044] Specifically, during implementation, the mixture of iron concentrate powder and lime powder is added to the second zone 2 (slag-iron layer melting zone) through the injection system 6. The injection system 6 uses oxygen as the transport medium for the mixture, while hydrogen is injected into the second zone 2 from the side, where it combusts and releases heat, providing heat for the material melting. Simultaneously, the molten material is transported to the slag-iron layer reduction zone. The slag-iron layer melting zone forms an independent, strongly oxidizing atmosphere, improving dephosphorization efficiency and achieving dephosphorization. The material is pre-melted in the slag-iron layer melting zone before entering the slag-iron layer reduction zone, reducing heat loss and melting time in the reduction zone and improving the reduction rate and efficiency. The molten material enters the slag-iron layer reduction zone, where it undergoes a melting reduction and desulfurization reaction with the molten iron brought in by the "spring" of reducing gas, resulting in slag-iron separation. The molten slag floats to the slag layer, while the molten iron sinks to the pre-reduced molten iron layer. The pre-reduced molten iron enters the third zone 3 through a "siphon" effect and undergoes deep reduction smelting with hydrogen gas entering from the bottom of the third zone 3, deeply removing oxygen and sulfur from the molten iron. This invention achieves precise control of the atmosphere transition from oxidizing to reducing by functionally dividing the slag-iron layer melting zone, slag-iron layer reduction zone, and deep reduction zone, enabling graded and deep removal of phosphorus, sulfur, and oxygen, and improving the removal limits of impurity components.

[0045] The present invention also provides a method for high-efficiency electro-hydrogen conversion and reduction smelting, employing the above-mentioned high-efficiency electro-hydrogen conversion and reduction smelting apparatus, comprising:

[0046] Step 1: At the beginning, industrial pure iron or sponge iron is added to Zone 1 as an induction heating medium and melted to form a pre-reduced molten iron layer;

[0047] Step 2: At the beginning, hydrogen gas is injected into the bottom of Zone 1. The hydrogen gas agitates the molten iron and causes a "springing" phenomenon, forming a slag-iron mixture layer above the pre-reduced molten iron layer (in the early stage of the reaction, the slag can be directly added to the molten slag; molten slag will continue to be generated during continuous production). The slag-iron mixture layer serves as the slag-iron layer reduction zone during continuous production.

[0048] Step 3: The mixture of iron concentrate powder and quicklime powder is added to the second zone 2 (i.e. slag-iron layer melting zone) through the injection system 6. The injection system 6 uses oxygen as the conveying medium for the mixture. The hydrogen gas generated by the electrolysis device 11 is injected into the second zone 2 from the first spray gun and then undergoes combustion and heat release, providing heat for the melting of the material. At the same time, the molten material is conveyed to the slag-iron layer reduction zone.

[0049] Step 4: The molten material enters the slag-iron layer reduction zone and undergoes a molten pre-reduction reaction with the molten iron brought by the "spring" below to form low-valence iron oxides. At the same time, it is reduced to metallic iron by high-temperature hydrogen and slag-iron separation occurs. The molten slag floats to the molten slag layer and the molten iron sinks to the pre-reduced molten iron layer.

[0050] Step 5: Open the sliding gate 4. The molten iron in the pre-reduced iron layer enters the third zone 3 through the "siphon" effect. After the molten iron layer in the third zone 3 reaches the specified height, close the sliding gate 4 and inject hydrogen gas from the bottom of the third zone 3 for deep reduction smelting. The amount of refining slag added is 8% to 10% of the mass of the molten iron. After deep reduction smelting, the oxygen and sulfur content in the molten iron is controlled below 10 ppm.

[0051] Specifically, in step 1 above, the temperature of the pre-reduced molten iron layer is controlled at 1600-1650℃.

[0052] Specifically, in step 2 above, during continuous production, high-temperature reducing gas from zone 3 can be injected from the middle of the pre-reduced molten iron layer to drive the molten iron into the slag-iron layer reduction zone.

[0053] Specifically, in step 3 above, if the binary basicity is too high, the slag phase melting temperature will be high and the slag viscosity will be high, reducing the diffusion rate of sulfur into the slag phase; if it is too low, the sulfur distribution rate in the slag phase will be reduced, affecting the desulfurization limit. Therefore, the binary basicity of iron concentrate powder and quicklime powder should be controlled at 3.0 to 3.5.

[0054] Specifically, in step 3 above, the oxidation reaction of sulfur and phosphorus occurs in zone 2 (i.e., the slag-iron layer melting zone), as detailed below:

[0055] O2 + 2H2 = 2H2O (1)

[0056] 11Fe2O3+2Fe3P+3CaO=28FeO+Ca3(PO4)2 (2)

[0057] 4Fe2O3+FeS+CaO=9FeO+CaSO4 (3)

[0058] Specifically, in step 4 above, the reaction in the slag-iron layer reduction zone is as follows:

[0059] Fe₂O₃ + Fe = 3FeO (5)

[0060] Fe3O4 + Fe = 4FeO (6)

[0061] FeO + H2 = Fe + H2O (7)

[0062] CaO+FeSO4+5H2=CaS+Fe+5H2O (8)

[0063] Specifically, in step 4 above, the FeO content in the slag is controlled at 5% to 8% during the reduction process to avoid the "phosphorus return" phenomenon. At the same time, calcium sulfate is reduced to calcium sulfide and enters the slag layer.

[0064] Specifically, in step 4 above, the phosphorus content of the reduced molten iron is <10ppm.

[0065] Specifically, in step 5 above, the reaction in zone 3 is as follows:

[0066] [O] + H2 = H2O (9)

[0067] CaO + FeS + H2 = CaS + Fe + H2O (10)

[0068] Specifically, step 5 above also includes:

[0069] Step 6: The molten iron after deep reduction enters the vacuum granulation chamber 7, where it is dispersed into fine molten iron particles by the granulator. By significantly increasing the surface area of ​​the molten iron, gaseous impurities in the molten iron are removed. This promotes the reaction of oxygen and hydrogen in the molten iron and also promotes the release of hydrogen.

[0070] Specifically, in step 6 above, in order to ensure that the hydrogen content in the molten iron is below 3 ppm, the vacuum degree is controlled at 20-30 Pa, and the oxygen content in the molten iron is reduced to below 5 ppm and the hydrogen content is reduced to below 1 ppm.

[0071] Specifically, the reaction in step 6 above is as follows:

[0072] [O] + 2[H] = H₂O (11)

[0073] 2[H]=H2 (12)

[0074] Specifically, the slag in the slag layer is discharged through an eccentric overflow method.

[0075] Specifically, in step 4 above, the reducing gas generated from the pre-reduction process is cooled to approximately 600°C after waste heat recovery by the waste heat recovery system 8. The resulting hydrogen and water vapor mixture is then heated to 900-950°C by the high-temperature dust removal device 9 and finally electrolyzed in the high-temperature oxide solid electrolysis cell of the high-temperature electrolysis device 11 to produce high-temperature hydrogen for recycling. By controlling the above process parameters, this invention ensures that the system electrolysis efficiency can reach over 43%, reducing the energy consumption for hydrogen production by electrolysis. Using this method, a separate hydrogen heating device is not required in this invention.

[0076] Specifically, considering that the corrosive effect of hydrogen on the electrode plate material intensifies at temperatures above 950℃, it is optimal to control the electrolysis temperature within the range of 900–950℃. Given that the high-temperature dust collector's tolerance temperature does not exceed 600℃, the temperature of the reducing gas before dust removal is controlled to be approximately 600℃. The reducing gas after dust removal is then heated by oxygen combustion, with the temperature controlled by adjusting the amount of oxygen supplied.

[0077]

[0078] Specifically, the hydrogen produced by the electrolysis unit 11 can be used for the reactions in the second zone 2 and the third zone 3.

[0079] Compared with the prior art, the electro-hydrogen high-efficiency conversion reduction smelting device of the present invention adopts a unique multi-zone induction furnace as the reduction smelting device, which can realize zoned dephosphorization and desulfurization, improve processing efficiency and molten iron quality. The second and third zones are connected by the "siphon" principle to realize integrated reduction smelting.

[0080] The induction furnace in the high-efficiency electro-hydrogen conversion reduction smelting device of the present invention is divided into a melting zone and a reduction zone by eccentric injection feeding. The melting zone directly heats the material by hydrogen combustion, which improves the heating efficiency and melting rate of the material. At the same time, oxygen plays the role of powder conveying and hydrogen plays the role of melt conveying.

[0081] The method of this invention achieves precise control over the atmosphere transition from oxidizing to reducing by functionally dividing the slag-iron layer into a melting zone, a reduction zone, and a deep reduction zone. This enables graded and deep removal of phosphorus, sulfur, and oxygen, increasing the removal limits of impurity components. It allows for zoned dephosphorization and desulfurization, improving processing efficiency and molten iron quality, resulting in high-purity molten iron.

[0082] The method of this invention uses vacuum granulation instead of conventional argon blowing for deep removal of hydrogen from molten iron, avoiding the use of argon and the drop in iron temperature. It further promotes the reaction between oxygen and hydrogen in the molten iron, while also promoting hydrogen overflow. This further improves the purity of the molten iron particles, ensuring that the oxygen content in the molten iron is reduced to below 5 ppm and the hydrogen content to below 1 ppm.

[0083] The method of the present invention first cools the reducing gas to meet the tolerance temperature of the high-temperature dust collector, and then raises the temperature to control the electrolysis temperature of the reducing gas, ensuring that the system electrolysis efficiency can reach more than 43%, reducing the energy consumption of electrolytic hydrogen production, and directly obtaining high-temperature hydrogen that meets the reduction requirements, avoiding the use of hydrogen heating devices, and ensuring the safety of each piece of equipment.

[0084] Example 1

[0085] This embodiment provides an efficient electro-hydrogen conversion reduction smelting apparatus, such as... Figure 1 As shown, the furnace includes a multi-zone induction furnace, comprising a first zone 1, a second zone 2, and a third zone 3. The second zone 2 and the third zone 3 are located on either side of the first zone 1, with the second zone 2 located in the lower middle part of the first zone 1 and directly connected to the first zone 1. The third zone 3 is connected to the bottom of the first zone 1 via a sliding nozzle 4. During reduction smelting, the second zone 2 serves as the slag-iron layer melting zone. The first zone 1 is divided from bottom to top into a pre-reduced molten iron layer, a slag-iron layer reduction zone, and a molten slag layer. The slag-iron layer melting zone is connected to the slag-iron layer reduction zone. The third zone 3 is divided from bottom to top into a deep-reduced molten iron layer and a refining slag layer.

[0086] Specifically, Zone 1 is cylindrical.

[0087] Specifically, the upper part of Zone 1 is equipped with a slag outlet 12.

[0088] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a batching system 5 and a blowing system 6 connected to the batching system 5. After the material is batched in the batching system 5, it is blown into the second zone 2 by the blowing system 6.

[0089] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a first spray gun, which is located on the side of the second zone 2 and is used to spray hydrogen into the second zone 2.

[0090] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a second spray gun, which is located on the side of the third zone 3 and is used to spray hydrogen into the third zone 3.

[0091] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a vacuum granulation chamber 7, which is located below the third zone 3.

[0092] Specifically, the high-efficiency electro-hydrogen conversion reduction smelting device also includes a waste heat recovery system 8, a high-temperature dust removal device 9, an oxygen combustion system 10, and a high-temperature electrolysis device 11 connected in sequence.

[0093] Example 2

[0094] like Figure 2As shown, this embodiment provides a method for high-efficiency electro-hydrogen conversion and reduction smelting, using the high-efficiency electro-hydrogen conversion and reduction smelting apparatus of Embodiment 1 above, including:

[0095] Step 1: Add industrial pure iron to Zone 1 as an induction heating medium and melt it to form a pre-reduced molten iron layer;

[0096] Step 2: Inject hydrogen gas into the bottom of Zone 1. The hydrogen gas agitates the molten iron, creating a "springing" phenomenon and forming a slag-iron mixture layer above the pre-reduced molten iron layer (in the early stage of the reaction, the slag can be directly added to the molten slag; molten slag will continue to be generated during continuous production).

[0097] Step 3: The mixture of iron concentrate powder and quicklime powder is added to the second zone 2 (i.e. slag-iron layer melting zone) through the injection system 6. The injection system 6 uses oxygen as the conveying medium for the mixture. The hydrogen gas generated by the high-temperature electrolysis device 11 is injected into the second zone 2 from the first spray gun and then undergoes combustion and heat release, providing heat for the melting of the material. At the same time, the molten material is conveyed to the slag-iron layer reduction zone.

[0098] Step 4: The molten material enters the slag-iron layer reduction zone and undergoes a molten pre-reduction reaction with the molten iron brought by the "spring" below to form low-valence iron oxides. At the same time, it is reduced to metallic iron by high-temperature hydrogen and slag-iron separation occurs. The molten slag floats to the molten slag layer and the molten iron sinks to the pre-reduced molten iron layer.

[0099] Step 5: Open the sliding gate 4. The molten iron in the pre-reduced iron layer enters the third zone 3 through the "siphon" effect. After the molten iron layer in the third zone 3 reaches the specified height, close the sliding gate 4 and inject hydrogen from the middle and lower part of the molten iron layer for deep reduction smelting. The amount of refining slag added is 8% to 10% of the mass of molten iron. After deep reduction smelting, the oxygen and sulfur content in the molten iron is controlled below 10 ppm.

[0100] Step 6: The molten iron after deep reduction enters the vacuum granulation chamber 7, where it is dispersed into fine molten iron particles by the granulator.

[0101] Specifically, in step 3 above, the composition of the selected iron concentrate powder is shown in Table 1 below, with a total iron content of 67% and sulfur and phosphorus contents of 0.01% each. The iron concentrate powder and quicklime powder are mixed in a ratio with a binary basicity of 3.0.

[0102] Table 1 Composition of iron concentrate powder

[0103] Element TFe FeO <![CDATA[Fe2O3]]> <![CDATA[Al2O3]]> CaO MgO <![CDATA[SiO2]]> P S content,% 67 1.04 94.6 0.64 0.89 0.68 2.61 0.03 0.01

[0104] Specifically, the process steps of steps 1-4 above are as follows: 10 kg of industrial pure iron is added to the first zone 1 of a 50 kg capacity multi-zone induction furnace as an induction heating medium and melted to form a pre-reduced molten iron layer. The induction heating temperature is controlled at 1600℃. Then, 5 kg of molten slag (excluding iron) is added to the first zone 1, and hydrogen is simultaneously injected from the bottom of the first zone 1. The hydrogen agitation creates a "springing" phenomenon, forming a slag-iron mixed layer above the pre-reduced molten iron layer. 10 kg of a mixture of iron concentrate powder with a binary basicity of 3.0 and quicklime powder is first melted at 1600℃, cooled, and then powdered. This powder is injected into the second zone 2 through the injection system 6, simulating the melting of the material in the slag-iron mixed layer in this invention before entering the reduction zone. Samples are taken from the slag layer and the pre-reduced molten iron layer every 5 minutes using a sampler and analyzed by chemical titration to determine the FeO content in the slag and the sulfur, phosphorus, and oxygen content in the pre-reduced molten iron. The experimental results are shown in Table 2. It can be seen that in the pre-reduction dephosphorization stage, when the FeO content in the slag is controlled above 5%, the phosphorus content in the molten iron can be removed to below 10 ppm. When the FeO content is above 8%, the change is not significant. In order to reduce the damage to iron, the FeO content in the slag is preferably controlled within the range of 5% to 8%.

[0105] Table 2. Changes in the composition of slag and molten iron.

[0106] FeO content in slag, % 3 5 8 10 Sulfur content in molten iron, ppm 12 20 25 38 Phosphorus content in molten iron, ppm 17 7 5 4 Oxygen content in molten iron, ppm 136 176 234 283

[0107] Specifically, in step 5 above, molten iron with an FeO content of 5% is used. The molten iron enters the third zone 3 through a "siphon" effect, and 3% to 10% of the molten iron mass of refining slag (with a composition similar to that of the reducing refining slag in a ladle furnace) is added. Excess hydrogen is then introduced from the lower part of the molten iron layer for deep reduction and desulfurization. The experimental results are shown in Table 3. It can be seen that after deep reduction, the phosphorus content in the molten iron decreases slightly, while the sulfur and oxygen contents decrease significantly, but the hydrogen content remains high. The preferred ratio of refining slag addition is 8% to 10% of the molten iron mass.

[0108] Table 3. Changes in molten iron composition under different amounts of refining slag added.

[0109] Refining slag addition ratio, % 3 5 8 10 Sulfur content in molten iron, ppm 11 8 4 3 Phosphorus content in molten iron, ppm 5 4 3 3 Oxygen content in molten iron, ppm 18 16 12 14 Hydrogen content in molten iron, ppm 30 34 32 35

[0110] Specifically, in step 6 above, molten iron with an added refining slag ratio of 8% is introduced into the vacuum granulation chamber 7 for granulation and degassing. The rotation speed of the granulation turntable is set to 2500 r / min. The hydrogen content in the molten iron after degassing under different vacuum degrees is shown in Table 4. According to the requirements, the hydrogen content in the molten iron must be below 3 ppm to not affect the quality. It can be seen that the requirements can be met when the vacuum degree is controlled in the range of 20-30 Pa, at which point the oxygen content in the molten iron can be below 5 ppm.

[0111] Table 4. Changes in molten iron composition under different vacuum levels.

[0112] Vacuum degree, Pa 20 30 40 50 Oxygen content in molten iron, ppm 4 5 7 9 Hydrogen content in molten iron, ppm 1 1 2 3

[0113] Specifically, in step 4 above, under the conditions that the reducing gas produced by pre-reduction has a composition of 50% H2-50% H2O and an outlet temperature of 1500-1600℃, in the conventional water electrolysis hydrogen production process, the reducing gas is first cooled to below 200℃ through waste heat recovery, then separated into hydrogen through dust removal, spray cooling, and dehydration, and the consumed hydrogen is replenished through water electrolysis. The thermal efficiency of the electricity generated by electrolysis for hydrogen production is set at 40% for steam power generation, and the electrolysis efficiency for room temperature water electrolysis for hydrogen production is 71%, resulting in a total system thermal efficiency of 28.37%.

[0114] Under the aforementioned coal gas conditions, in the process of this invention, the reducing coal gas is first cooled to approximately 600°C via a waste heat recovery system. After high-temperature dust removal, it is then used for hydrogen production via high-temperature solid electrolyte electrolysis for recycling. The thermal efficiency of the electricity generated from hydrogen electrolysis through steam power generation is set at 40%, the electrolysis efficiency of high-temperature steam is 90%, and the physical heat efficiency of steam is 90%. The system thermal efficiency of hydrogen production via high-temperature solid oxide electrolysis at different temperatures is shown in Table 5. It can be seen that the higher the temperature, the higher the electrolysis thermal efficiency. Considering that the corrosiveness of hydrogen to the electrode plate material increases above 950°C, the optimal electrolysis temperature is controlled within the range of 900–950°C.

[0115] Since the high-temperature dust collector can withstand temperatures not exceeding 600℃, the reducing gas after dust removal can be heated by oxygen combustion, with the temperature controlled by adjusting the amount of oxygen injected. This invention, by controlling the above process parameters, ensures that the system's electrolysis efficiency can reach over 43%, thus reducing the energy consumption for hydrogen production through electrolysis.

[0116] Table 5 High-Temperature Electrolysis Hydrogen Production Efficiency

[0117] Electrolysis temperature, °C 600 700 800 900 950 1000 System efficiency, % 41.78 42.36 42.96 43.58 43.89 44.21

[0118] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for efficient electro-hydrogen conversion and reduction smelting, characterized in that, An electro-hydrogen high-efficiency conversion reduction smelting device is adopted, which includes a multi-zone induction furnace, comprising a first zone (1), a second zone (2), and a third zone (3); the second zone (2) and the third zone (3) are located on both sides of the first zone (1), the second zone (2) is located in the lower middle part of the first zone (1), and the second zone (2) is directly connected to the first zone (1); the third zone (3) is connected to the bottom of the first zone (1) through a sliding nozzle (4); during reduction smelting, the second zone (2) serves as the slag-iron layer melting zone, and the first zone (1) is divided from bottom to top into a pre-reduced molten iron layer, a slag-iron layer reduction zone, and a molten slag layer; the slag-iron layer melting zone is connected to the slag-iron layer reduction zone; the third zone (3) is divided from bottom to top into a deep-reduced molten iron layer and a refining slag layer; The high-efficiency electro-hydrogen conversion reduction smelting apparatus also includes a batching system (5) and a spraying system (6) connected to the batching system (5). After the material is batched in the batching system (5), it is sprayed to the second zone (2) through the spraying system (6). The high-efficiency electro-hydrogen conversion reduction smelting apparatus also includes a vacuum granulation chamber (7), which is located below the third zone (3). The high-efficiency electro-hydrogen conversion reduction smelting device also includes a waste heat recovery system (8), a high-temperature dust removal device (9), an oxygen combustion system (10), and a high-temperature electrolysis device (11) connected in sequence. The efficient electro-hydrogen conversion reduction smelting method includes: Step 1: At the beginning, industrial pure iron or sponge iron is added to the first zone (1) as an induction heating medium and melted to form a pre-reduced molten iron layer; Step 2: A slag-iron mixture layer is formed above the pre-reduced molten iron layer; the slag-iron mixture layer serves as the slag-iron layer reduction zone during continuous production. Step 3: The mixture of iron concentrate powder and quicklime powder is added to the second zone (2) through the injection system (6). The injection system (6) uses oxygen as the conveying medium of the mixture. The hydrogen generated by the high-temperature electrolysis device (11) is injected into the second zone (2) from the first spray gun and then burns and releases heat to provide heat for the melting of the material. At the same time, the melted material is transported to the slag-iron layer reduction zone. Step 4: The molten material enters the slag-iron layer reduction zone and undergoes a molten pre-reduction reaction with the molten iron brought by the "spring" below to form low-valence iron oxides. At the same time, it is reduced to metallic iron by high-temperature hydrogen and slag-iron separation occurs. The molten slag floats to the molten slag layer and the molten iron sinks to the pre-reduced molten iron layer. Step 5: Open the sliding gate (4) and the molten iron of the pre-reduced molten iron layer enters the third zone (3). After the molten iron layer in the third zone (3) reaches the specified height, close the sliding gate (4) and carry out deep reduction smelting. After deep reduction smelting, the oxygen and sulfur content in the molten iron is controlled below 10 ppm. Step 6: After deep reduction, the molten iron enters the vacuum granulation chamber (7) and is dispersed into fine molten iron particles under the action of the granulator. By increasing the surface area of ​​the molten iron, gaseous impurities in the molten iron are removed. In step 3, the binary basicity of the iron concentrate powder and quicklime powder is controlled to be 3.0~3.5; In step 4, the reducing gas is first cooled by waste heat recovery to meet the tolerance temperature of the high-temperature dust removal device. The mixed gas of hydrogen and water vapor obtained from dust removal is then heated by oxygen combustion and finally electrolyzed to produce hydrogen. The electrolysis temperature is controlled at 900~950℃. In step 4, the FeO content in the slag is controlled to be between 5% and 8% during the reduction process; In molten iron, the oxygen content is reduced to below 5 ppm and the hydrogen content is reduced to below 1 ppm.

2. A high-efficiency electro-hydrogen conversion reduction smelting apparatus, characterized in that, The electro-hydrogen high-efficiency conversion and reduction smelting apparatus is used to implement the electro-hydrogen high-efficiency conversion and reduction smelting method according to claim 1. The electro-hydrogen high-efficiency conversion and reduction smelting apparatus includes a multi-zone induction furnace, which includes a first zone (1), a second zone (2), and a third zone (3). The second zone (2) and the third zone (3) are located on both sides of the first zone (1). The second zone (2) is located in the lower middle part of the first zone (1). The second zone (2) is directly connected to the first zone (1). The third zone (3) is connected to the bottom of the first zone (1) through a sliding gate (4). The high-efficiency electro-hydrogen conversion reduction smelting apparatus also includes a batching system (5) and a spraying system (6) connected to the batching system (5). After the material is batched in the batching system (5), it is sprayed to the second zone (2) through the spraying system (6). The high-efficiency electro-hydrogen conversion reduction smelting apparatus also includes a vacuum granulation chamber (7), which is located below the third zone (3). The electro-hydrogen high-efficiency conversion reduction smelting device also includes a waste heat recovery system (8), a high-temperature dust removal device (9), an oxygen blowing combustion system (10), and a high-temperature electrolysis device (11) connected in sequence. During reduction smelting, the second zone (2) serves as the slag-iron layer melting zone, and the first zone (1) is divided from bottom to top into a pre-reduced molten iron layer, a slag-iron layer reduction zone, and a molten slag layer; the slag-iron layer melting zone is connected to the slag-iron layer reduction zone; the third zone (3) is divided from bottom to top into a deep-reduced molten iron layer and a refining slag layer.

3. The high-efficiency electro-hydrogen conversion reduction smelting apparatus according to claim 2, characterized in that, The electro-hydrogen high-efficiency conversion reduction smelting device also includes a first spray gun, which is located on the side of the second zone (2) and is used to spray hydrogen into the second zone (2).

4. The high-efficiency electro-hydrogen conversion reduction smelting apparatus according to claim 2, characterized in that, The electro-hydrogen high-efficiency conversion reduction smelting device also includes a second spray gun, which is located on the side of the third zone (3) and is used to spray hydrogen into the third zone (3).

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