Green low-carbon smelting reduction short process smelting process and system

Abstract

The application discloses a kind of green low-carbon smelting process and system of short process of melting reduction, comprising the following steps: 1) iron-containing material is screened into iron-containing fine material and iron-containing coarse material;The iron-containing fine material is sent into ore powder injection device;The iron-containing coarse material is mixed into iron-containing mixture after hydrogen-based pre-reduction;2) the reduced material is ground and dried, to obtain reduced powder;3) high-temperature coal gas discharged from smelting reduction furnace is cooled by heat exchange, and the coal gas is purified into clean coal gas, a part of the clean coal gas is pressurized into high-pressure clean coal gas;4) a part of the high-pressure clean coal gas is used as the injection gas of the reduced powder, and the reduced powder is injected into the iron bath pool of the smelting reduction furnace;Another part of the high-pressure clean coal gas is used as the injection gas of the high-temperature coal gas, and the mixed injection gas after injection is used as the injection gas of the iron-containing mixture.The method has the advantages of short process, low carbon, green environmental protection, etc., and can achieve the purpose of green low-carbon smelting of smelting reduction short process.

Description

Technical Field

[0001] This invention relates to the field of metallurgical technology, and in particular to a green, low-carbon, short-process smelting process and system for melting and reduction. Background Technology

[0002] Traditional steel production primarily utilizes the blast furnace process. While mature, the blast furnace process suffers from high pollution, high energy consumption, and high carbon emissions. Although non-blast furnace processes have diversified in recent years and reduced pollution to some extent, even the more mature ones still face challenges such as high consumption of reducing materials leading to high carbon emissions and high overall costs. Therefore, developing a green, low-carbon, low-energy-consumption, and low-pollution stable short-process smelting technology is of great significance. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a green, low-carbon molten reduction short-process smelting process; the present invention also provides a green, low-carbon molten reduction short-process smelting system.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the method of the present invention includes the following steps: 1) the iron-containing material is screened into iron-containing fine material and iron-containing coarse material; the iron-containing fine material is fed into the ore powder injection device; the iron-containing coarse material is subjected to hydrogen-based pre-reduction and then mixed with the iron-containing fine material to form an iron-containing mixture. 2) Grind and dry the reducing material to obtain reducing powder; 3) The high-temperature coal gas discharged from the molten reduction smelting furnace is cooled by heat exchange and purified into clean coal gas. A portion of the clean coal gas is pressurized into high-pressure clean coal gas. 4) A portion of the high-pressure clean coal gas is used as the injection carrier gas for the reducing powder, which is then injected into the iron bath of the molten reduction furnace; another portion of the high-pressure clean coal gas is used as the ejector gas to eject the high-temperature coal gas, and the mixed ejector gas after ejection is used as the injection carrier gas for the iron-containing mixture, which is then injected into the iron bath of the molten reduction furnace; the coal gas injected into the iron bath as carrier gas and the reducing powder simultaneously undergo a reduction reaction with the iron-containing material.

[0005] 5) The molten reduction smelting furnace body is equipped with two siphon iron inlets and two slag inlets.

[0006] Furthermore, in step 4), the impact depth of the reducing powder and the iron-containing mixture injected into the iron bath is 1 to 2 m.

[0007] Furthermore, in step 1), the iron-containing material is preheated before sieving, with the preheating temperature controlled at 30–1000°C; hydrogen or hydrogen-rich gas is used for hydrogen-based pre-reduction, with the hydrogen or hydrogen-rich gas reduction temperature at 850–1300°C.

[0008] Furthermore, in step 1), the particle size of the iron-containing fine material is <3mm, and the particle size of the iron-containing coarse material is ≥3mm.

[0009] Furthermore, in step 4), the temperature of the mixed ejector gas is 200–1200℃, the pressure is ≥400kPa, and the blowing speed is controlled at 30–60m / s.

[0010] Furthermore, the process also includes the following steps: during the molten reduction process, oxygen-enriched hot air is injected from the furnace shoulder of the molten reduction smelting furnace through a hot air lance in a swirling manner, so as to generate a vortex reaction interface inside the furnace.

[0011] To solve the above-mentioned technical problems, the technical solution adopted by the system of the present invention is as follows: It includes a molten reduction smelting furnace, a gas reforming device, a hydrogen-based heating device, a No. 1 heat exchanger, a No. 2 heat exchanger, a dust removal device, a gas pressurizing device, an ejector device, a processing device, a pulverized coal injection device, a screening device, a hydrogen-based reduction device, and a mineral powder injection device; the molten reduction smelting furnace is equipped with a injection pipe extending into the molten iron bath; the inlet of the processing device is connected to the reducing material supply source, and the outlet is connected to the pulverized coal injection device, the outlet of the pulverized coal injection device is connected to the injection pipe; the inlet of the screening device is connected to the iron-containing material supply source, the coarse material outlet is connected to the hydrogen-based reduction device, the outlet of the hydrogen-based reduction device and the fine material outlet of the screening device are connected to the mineral powder injection device, the outlet of the mineral powder injection device is connected to the injection pipe; the high-temperature gas of the molten reduction smelting furnace... The outlet is divided into three paths. One path connects sequentially to the gas reforming unit, the hydrogen-based heating unit, the No. 2 heat exchanger, and the dust removal unit. The outlet of the dust removal unit connects to the gas pressurizing unit. The outlet of the gas pressurizing unit connects to the outlet of the pulverized coal injection unit, serving as the carrier gas for the reducing powder in the pulverized coal injection unit. The other path connects to the high-speed flow inlet of the ejector. The high-temperature gas outlet of the molten reduction smelting furnace connects to the low-speed flow inlet of the ejector. The outlet of the ejector connects to the outlet of the ore powder injection unit, serving as the carrier gas for the iron-containing mixture in the ore powder injection unit. The high-temperature gas outlet of the molten reduction smelting furnace connects to the No. 2 heat exchanger via the No. 1 heat exchanger. The hydrogen-based gas inlet of the hydrogen-based heating unit connects to a hydrogen or hydrogen-rich supply source, and the hydrogen-based gas outlet connects to the hydrogen-based reduction unit.

[0012] Furthermore, a blower, a hot blast stove, and a hot blast injection device are also provided; the outlet of the blower is connected to the inlet of the hot blast stove, and the outlet of the hot blast stove is connected to the inlet of the hot blast injection device; the hot blast injection device is equipped with a hot blast gun, at least one hot blast gun, which extends into the furnace from the shoulder of the molten reduction smelting furnace at a clockwise or counterclockwise angle.

[0013] Furthermore, the hot air gun is tilted at an angle of 55° to 85° with the liquid surface inside the furnace.

[0014] Furthermore, the molten reduction smelting furnace is equipped with two molten iron outlets.

[0015] The beneficial effects of adopting the above technical solution are as follows: This invention is based on a process of directly reducing molten iron by mixing iron-containing materials, reducing materials, and spontaneously reducing gases; using purified coal gas mixed by injection and pressurization as a carrier gas, the iron-containing materials, reducing materials, and flux are mixed and injected into a molten reduction furnace, where gas-liquid and liquid-liquid molten reduction reactions occur. The coal gas directly affects the consumption of reducing materials in the molten reduction furnace and participates in the combustion reaction in the upper part of the furnace, directly affecting the occurrence of the reverse reaction and indirectly reducing the consumption of reducing materials. It fully utilizes the sensible heat of the reducing furnace gas, achieving coal gas enrichment and upgrading without the need for additional heat supply. This invention can significantly reduce the consumption of reducing materials during the reduction process, significantly improving the problems of high pollution and high emissions in traditional blast furnaces and high energy consumption in traditional molten reduction, reducing investment costs and carbon emissions, and has a stable development prospect.

[0016] This invention modifies the utilization of hydrogen or hydrogen-rich materials in the iron-containing material processing step of a molten reduction furnace. By pre-reducing large iron-containing particles after screening with hydrogen or hydrogen-rich materials, it not only replaces the carbon required for reduction with hydrogen, but also significantly reduces the reaction load of the molten reduction furnace. This avoids the long-standing problem of low heat exchange efficiency in molten reduction furnaces, and simultaneously reduces carbon consumption in molten reduction furnaces from both energy substitution and efficiency utilization perspectives, thereby reducing carbon emissions from the molten reduction process.

[0017] This invention provides a molten reduction smelting furnace with two siphon taps and two slag taps. While reducing carbon emissions, this invention also significantly increases the production capacity of the molten reduction smelting furnace. The dual taps and slag taps can better adapt to actual production scheduling, which is conducive to the uniform flow of molten iron in the furnace and prevents refractory erosion and segregation caused by uneven flow of molten iron in the furnace. Moreover, in extreme cases, as long as one siphon tap and slag tap are operating normally, the production needs under emergency conditions can be met.

[0018] This invention reduces the consumption of reducing materials by changing the utilization of reducing gases and materials, and by adjusting the proportion of gas-liquid and liquid-liquid reactions occurring in the molten reduction smelting furnace and the reverse reaction generated in the upper space of the furnace. It also eliminates the coking, sintering, and pelletizing processes associated with traditional blast furnaces, significantly reducing pollutant emissions and carbon emissions, and simplifying the process flow. This provides an important pathway for the further green and ultra-low-carbon development of the smelting industry.

[0019] This invention effectively lowers the high energy consumption technical barrier of current smelting reduction technology, significantly shortens the smelting process compared to traditional blast furnaces, and reduces pollutant emissions. This invention directly eliminates the coking, sintering, and pelletizing processes in traditional blast furnaces, simplifying the process and greatly reducing investment costs. Due to the unique characteristics of the reducing gas produced, this invention can significantly reduce the consumption of solid reducing materials, thereby lowering production costs. In summary, this invention is a green, short-process smelting technology with low investment costs, low operating costs, low pollutant emissions, low carbon consumption, and the ability to produce high-purity molten iron. Attached Figure Description

[0020] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0021] Figure 1 This is a schematic diagram of the system structure of the present invention; Figure 2 This is a schematic diagram of the molten reduction smelting furnace described in this invention; Figure 3 This is a schematic diagram of the structure of the hot air spray gun device described in this invention; Figure 4 This is a top view of the hot air spray gun device described in this invention.

[0022] In the diagram: 1. Furnace body; 2. High-temperature gas outlet; 3. Circular pipe; 4. Hot air lance; 5. Blowing pipe; 6. Molten iron outlet; 7. Slag outlet. Detailed Implementation

[0023] Figure 1 As shown, this green, low-carbon smelting reduction short-process smelting technology includes the following steps: 1) Pretreatment: The iron-containing material is preheated at a temperature controlled between 30 and 1000°C to obtain the preheated iron-containing material; it is best to use high-temperature preheating generated by the combustion of coal gas containing CO and H2 components, preferably containing CO 10-50 vol%, H2 1-10 vol%, and dust content ≤10 mg / m³. 3 The gas is preferably purified gas obtained by cooling and removing dust from high-temperature gas discharged from a molten reduction smelting furnace. The iron-containing material can be iron ore, pellets, or iron ore powder.

[0024] The preheated iron-containing material is screened into fine iron-containing material with a particle size <3mm and coarse iron-containing material with a particle size ≥3mm. The fine iron-containing material is conveyed to the mineral powder injection device. The coarse iron-containing material enters the hydrogen-based reduction device for pre-reduction treatment with hydrogen; the pre-reduced coarse iron-containing material is then conveyed to the mineral powder injection device and mixed with the fine iron-containing material to form an iron-containing mixture.

[0025] The pre-reduction process involves the following steps: Iron-containing material enters the hydrogen-based reduction unit from the top, where it reacts with hydrogen-based gas entering from the bottom. The hydrogen-based gas, either hydrogen or hydrogen-rich gas, is used, and its temperature is 850–1300°C. The reduction rate of the hydrogen or hydrogen-rich gas varies under different temperatures and pressures. Typically, the reduction of iron ore by hydrogen or hydrogen-rich gas is within the chemical kinetic control zone, and the rate depends primarily on the partial pressure and temperature of the hydrogen or hydrogen-rich gas. The reaction rate is controlled by adjusting the temperature and pressure of the hydrogen or hydrogen-rich gas to ensure the degree of pre-reduction remains within a controllable range. Before entering the hydrogen-based reduction unit, the hydrogen-based gas is first heated to 800–1000°C by heat exchange with the modified coal gas from step 3), and then further heated to 850–1300°C before entering the hydrogen-based reduction unit for pre-reduction. The remaining pure hydrogen gas after pre-reduction is then subjected to wet dust removal and pressurized for reuse.

[0026] The pre-reduction treatment reaction is: Fe2O3(s) + H2(g) → Fe(s) + H2O(g); The rate of pure hydrogen reduction varies under different temperatures and pressures. Under normal circumstances, the reaction of pure hydrogen reduction of iron ore is in the chemical kinetic control region, and the rate mainly depends on the partial pressure of hydrogen and temperature. A common form is shown in equation (I):

[0027] In the formula, n is the reaction order, usually taken as 1 (first-order reaction); k is the rate constant; P H2 This represents the partial pressure of hydrogen gas, expressed in kPa.

[0028] The rate constant k follows the Arrhenius equation, as shown in equation (II):

[0029] In the formula, A is the pre-exponential factor; Ea is the activation energy; R is the gas constant; and T is the temperature, °C.

[0030] The reaction rate is controlled by adjusting the temperature and pressure of pure hydrogen, ensuring that the pre-reduction degree of the iron-containing material after reduction in the hydrogen-based reduction unit is within a controllable range. The pre-reduced iron-containing material is discharged by a feeder and then transported back to the hot ore injection chamber via a bucket elevator for use in injection. The remaining pure hydrogen gas after the reaction is completed is then pressurized and reused after wet dust removal.

[0031] In this stage, hydrogen-based gas is used to pre-reduce large iron-containing materials with a particle size ≥3mm, which can effectively reduce carbon emissions from smelting. The reduction reaction of molten reduction is: Fe2O3(s) + 3C(s) → 2Fe(s) + 3CO(g). In carbon-based reduction, 322kg of carbon (187kg for reduction and 135kg for heating) and 175Nm³ of oxygen are required to reduce 1 ton of iron.

[0032] Based on calculations using a hydrogen-based reduction device to increase the pre-reduction degree of the mixed iron-containing material to approximately 30%, the carbon emission per ton of iron produced by this process is only 0.331 t. Even if the hydrogen-based reduction device cannot increase the pre-reduction degree of the mixed iron-containing material, this process can still achieve carbon emissions of 0.45 t per ton of iron. This is a significant reduction compared to the 1.1 t per ton of iron produced by the traditional blast furnace process.

[0033] The application of the hydrogen-based reduction device for pre-reduction is aimed at the pre-reduction of iron-containing materials in molten reduction smelting furnaces to reduce carbon emissions. There is no absolute requirement for the degree of pre-reduction of iron-containing materials, and the production capacity is significantly improved compared to the original direct hydrogen injection into the smelting furnace.

[0034] 2) Grinding and drying: The reducing material is ground and dried to obtain reducing powder; the particle size of the reducing powder is ≤3mm and the moisture content is ≤3wt%. The reducing material can be coal powder or coke powder.

[0035] 3) Gas Purification: A portion of the high-temperature coal gas discharged from the molten reduction smelting furnace undergoes gas reforming to obtain reformed coal gas. This reformed coal gas exchanges heat with the hydrogen-based gas from step 1). Another portion of the high-temperature coal gas discharged from the molten reduction smelting furnace also undergoes heat exchange. These two gas mixtures are then cooled and purified to become clean coal gas. The hydrogen-based gas, heated by the reformed coal gas, enters a hydrogen-based reduction device as a reducing gas for pre-reduction. A portion of the clean coal gas is used as fuel, and another portion is pressurized to become high-pressure clean coal gas. The high-pressure clean coal gas preferably contains 10-50 vol% CO, 1-10 vol% H2, and a dust content ≤10 mg / m³. 3 The temperature of the high-pressure clean coal gas is ≤250℃ and the pressure is ≥400KPa.

[0036] The gas upgrading process uses the following materials: 80-90% carbon-containing raw materials or other lumpy materials, 5-10% dolomite, and 5-10% limestone; other lumpy materials include biomass; the particle size of the upgraded materials is greater than 40mm. The high-temperature gas discharged from the molten reduction smelting furnace has a temperature of 1450-1650℃ and a pressure ≤100kPa. This high-temperature sensible heat is used to react the upgraded materials with the gas, eliminating the need for additional heat. The temperature of the upgrading working space is 1100-1300℃, and the temperature of the upgraded gas is 800-1000℃. The purpose of upgrading a portion of the gas is twofold: first, the high-temperature gas generated by the molten reduction smelting furnace is too large, approximately 240,000 cubic meters per hour, and upgrading the entire amount would be too much; second, the high-temperature gas generated by the molten reduction smelting furnace has a slightly lower calorific value than the gas generated by ordinary smelting, and upgrading a portion and mixing it effectively improves the quality of use for subsequent users and reduces costs.

[0037] 4) Injector gas injection: The high-pressure clean coal gas is divided into two parts; one part of the high-pressure clean coal gas is used as the injection carrier gas for the reducing powder, which is injected into the iron bath pool below the liquid slag-iron interface in the molten reduction furnace; the other part of the high-pressure clean coal gas is used as the injection gas to inject the high-temperature coal gas discharged from the molten reduction furnace. The mixed injection gas after injection is used as the injection carrier gas for the iron-containing mixture, which is injected into the iron bath pool of the molten reduction furnace. The coal gas and reducing powder injected into the iron bath pool as carrier gas simultaneously undergo a reduction reaction with the iron-containing materials.

[0038] The temperature of the mixed ejector gas is 200–1200℃, the pressure is ≥400kPa, and the injection speed is controlled at 30–60m / s. The impact depth of the reducing powder and iron-containing mixture injected into the molten iron bath is 1–2m. The material ratio is adjusted according to the composition and temperature of the molten iron to ensure sufficient reaction. The ratio of reducing gas (i.e., coal gas), reducing powder, and iron-containing materials is controlled at a weight ratio of 0.1–100:0.1–80:0.1–100 to ensure that the temperature inside the molten reduction furnace is stable at 1400–1650℃.

[0039] 5) Vortex reaction: Figure 2-4 As shown, during the molten reduction process, oxygen-enriched hot air is injected into the furnace shoulder of the molten reduction smelting furnace through a hot air lance in a swirling manner, creating a vortex-like reaction interface inside the furnace. The oxygen-enriched hot air has an oxygen content of 21-100 vol%, a temperature ≥20℃, and the injection angle and speed are designed to form a swirling flow and create a vortex on the reaction liquid surface, enabling it to quickly react with the reducing gases inside the furnace to generate heat. The preferred injection angle is 55-85° with the horizontal plane of the liquid surface inside the furnace, 35-5° with the vertical plane, and 5-85° with the horizontal line of the hot air lance and the center point of the furnace.

[0040] 6) By supplementing the coal gas as carrier gas in step 4) and introducing oxygen-enriched hot air into the molten reduction furnace in step 5), the reaction ratio between reducing gas and oxygen is increased. This generates more heat under the same oxygen consumption conditions, thereby reducing the reverse reaction rate in the furnace and significantly reducing carbon consumption. The reverse reaction mainly refers to the direct reaction of oxygen with carbon (C) in the furnace to produce CO, resulting in reduced carbon consumption and oxygen utilization efficiency. Using the above process, low-carbon smelting can be achieved, with the resulting molten iron having a carbon content of 3.0%–4.5 wt%.

[0041] Figure 1-4 As shown, this green, low-carbon smelting reduction short-process smelting system includes a smelting reduction smelting furnace, a gas reforming unit, a hydrogen-based heating unit, a No. 1 heat exchanger, a No. 2 heat exchanger, a dust removal unit, a gas pressurizing unit, an ejector unit, a processing unit, a pulverized coal injection unit, a pretreatment unit, a screening unit, a hydrogen-based reduction unit, and a ore powder injection unit. The smelting reduction smelting furnace includes a furnace body 1, with a high-temperature gas outlet 2 at the top. The smelting reduction smelting process takes place in the lower liquid slag-iron zone within the furnace body 1. Part of the gas generated during smelting is burned in the upper part of the furnace body, releasing heat to provide heat for the lower smelting process; the remaining part is discharged outside the furnace through the high-temperature gas outlet 2 along with the combustion exhaust gas. The smelting reduction smelting furnace is equipped with a blowpipe 5 inserted into the molten iron bath pool inside the furnace body 1. The smelting reduction smelting furnace is also equipped with a hot air injection device, which includes an annular pipe 3 and a hot air nozzle 4. The annular pipe 3 encircles the top of the furnace body 1. One end of the hot air lance 4 is connected to the annular pipe 3, and the other end extends from the top of the furnace into the molten reduction smelting furnace. The hot air lance is located on the furnace shoulder of the molten reduction smelting furnace and is inserted into the furnace at an angle downwards. There is at least one hot air lance 4, and preferably several, such as... Figure 3 The furnace is equipped with three or more hot air jets 4 evenly distributed circumferentially on the annular pipe 3, all inserted into the furnace at a clockwise or counterclockwise angle downwards. The angle of the hot air jets is 55-85° with the horizontal plane and 35-5° with the vertical plane, and 5-85° with the horizontal line connecting the hot air jet and the center point of the furnace. After the hot air is injected into the molten reduction smelting furnace through the jets, it forms a separate combustion zone. Due to the influence of the jet angle, the combustion zones formed by each zone extend in the direction of the jet, ultimately forming a large vortex-type high-temperature combustion interface in the molten reduction smelting furnace. This directly increases the heat exchange efficiency of the molten reduction smelting furnace in this invention. The increased heat exchange efficiency reduces the extra carbon consumed in the furnace for supplemental heating, thereby directly reducing the carbon emissions of the molten reduction smelting furnace.

[0042] Figure 2As shown, the molten iron reduction smelting furnace has two molten iron outlets 6 on the lower side of the furnace body 1 to discharge the molten iron produced by the reaction to the ladle. The molten iron outlets 6 are preferably siphon taps. Two slag outlets 7 are provided on the bottom side of the furnace body 1 to discharge molten slag to the slag granulation treatment system. The dual molten iron outlet and dual slag outlet configuration facilitates production organization, promotes uniform flow of molten iron within the furnace, and prevents refractory material erosion and segregation caused by uneven molten iron flow. Furthermore, in extreme cases, the normal operation of just one molten iron outlet 6 and slag outlet is sufficient to meet production needs under emergency conditions.

[0043] Figure 1-4 As shown, in this green, low-carbon smelting reduction short-process smelting system, the inlet of the processing device is connected to the reducing material supply source, and the outlet is connected to the inlet of the pulverized coal injection device. The outlet of the pulverized coal injection device is connected to the injection pipe 5. The processing device is a heating treatment device. The inlet of the pretreatment device is connected to the iron-containing material supply source, and the outlet is connected to the inlet of the screening device. The screening device has a coarse material outlet and a fine material outlet. The fine material outlet is connected to the inlet of the ore powder injection device. The coarse material outlet of the screening device is connected to the feed inlet of the hydrogen-based reduction device, and the outlet of the hydrogen-based reduction device is connected to the inlet of the ore powder injection device. The screening device is preferably a vibrating screen. The outlet of the ore powder injection device is connected to the injection pipe 5. The high-temperature gas outlet of the smelting reduction smelting furnace is connected to three paths. The first path is connected to the inlet of the gas reforming device, the outlet of the gas reforming device is connected to the gas inlet of the hydrogen-based heating device, and the gas outlet of the hydrogen-based heating device is connected to the inlet of the No. 2 heat exchanger. The second path of the high-temperature gas outlet of the smelting reduction smelting furnace is connected to the inlet of the No. 1 heat exchanger, and the outlet of the No. 1 heat exchanger is connected to the inlet of the No. 2 heat exchanger. The outlet of the #2 heat exchanger is connected to the inlet of the dust removal device. The outlet of the dust removal device has three connections, the first of which is connected to the inlet of the gas pressurization device. The hydrogen-based gas inlet of the hydrogen-based heating device is connected to the hydrogen supply source, and the hydrogen-based gas outlet is connected to the reducing gas inlet of the hydrogen-based reduction device. In this way, the high-temperature coal gas can exchange heat with the hydrogen-based gas within the hydrogen-based heating device.

[0044] Figure 1-4As shown, in this green, low-carbon, short-process smelting reduction system, the outlet of the gas pressurizing device is connected to two paths. The first path connects to the outlet of the pulverized coal injection device. This allows high-pressure clean coal gas to be used as the carrier gas for the reducing powder in the pulverized coal injection device, carrying the reducing powder through injection pipe 5 into the liquid slag-iron zone of the smelting reduction furnace. The second path of the gas pressurizing device outlet connects to the high-speed flow inlet of the ejector device, and the third path of the high-temperature coal gas outlet of the smelting reduction furnace connects to the low-speed flow inlet of the ejector device. The outlet of the ejector device connects to the outlet of the ore powder injection device. This allows the mixed ejector gas after ejection to be used as the carrier gas for the iron-containing mixture in the ore powder injection device, carrying the iron-containing mixture through injection pipe 5 into the liquid slag-iron zone of the smelting reduction furnace.

[0045] Figure 1-4 As shown, this green, low-carbon smelting reduction short-process smelting system also includes a blower and a hot blast stove. The outlet of the blower is connected to the inlet of the hot blast stove, and the outlet of the hot blast stove is connected to the inlet of the hot blast injection device, i.e., the inlet of the annular pipe 3 in the hot blast injection device. In this way, oxygen-enriched hot air is evenly distributed to the hot blast lances 4 inserted into the furnace through the annular pipe 3. The oxygen-enriched hot air is injected in a swirling manner from the inclined top of the smelting reduction smelting furnace through three evenly distributed hot blast lances, generating a vortex reaction interface in the smelting reduction smelting furnace, causing the lower liquid reaction zone to surge, promoting the reaction. The molten iron produced by the reaction is discharged to the ladle through the molten iron outlet 6, and the slag is discharged to the slag granulation treatment system through the slag outlet 7 of the smelting reduction smelting furnace.

[0046] Figure 1-4 As shown, in this green, low-carbon smelting reduction short-process smelting system, the second outlet of the dust removal device is connected to a hot blast stove to provide reducing gas as fuel. The inlet of the hot blast stove is also connected to an oxygen source, and the outlet is connected to the smelting reduction furnace to provide oxygen-enriched hot air; the oxygen source can be an oxygen generator. The third outlet of the dust removal device is connected to a gas pipeline to utilize the purified gas as fuel, and excess purified gas is used as fuel. The high-temperature dust-laden gas discharged from the smelting reduction furnace, after heat exchange cooling, enrichment modification, and dust removal, becomes pure gas, which enters the pretreatment device to pretreat iron-containing materials.

[0047] Example 1: This melt reduction short-process includes the following steps: (1) Pretreatment: The iron-containing material is preheated by reducing gas containing CO and H2. The preheating temperature is controlled at 650±30℃. The treated iron-containing material is screened by a vibrating screen. The iron-containing material with a particle size <3mm is transported to the mineral powder injection device by a bucket elevator, and the iron-containing material with a particle size ≥3mm is transported to the silo of the hydrogen-based reduction device by another bucket elevator. For iron-containing materials ≥3mm, hydrogen-based pre-reduction is performed. 50,000 Nm³ / h of high-temperature coal gas (900℃) obtained from the coal gas reforming in step 3) is exchanged with hydrogen for heat. Electric heating is used at the end of the heat exchanger to control the hydrogen temperature at 1000℃. The heated hydrogen is then piped to the bottom of the hydrogen-based reduction unit at a rate of 30,000 Nm³ / h. Simultaneously, the iron-containing material in the hydrogen-based reduction silo is stably fed to the upper part of the hydrogen-based reduction unit by a feeder at a feeding rate of 30 tons / hour. The iron-containing material undergoes a reduction reaction inside the hydrogen-based reduction unit. After pre-reduction, the iron-containing material is discharged by the feeder and then transported back to the ore powder injection device by a bucket elevator to be mixed with the preheated small-particle iron-containing material. The pre-reduction degree after mixing is approximately 30%.

[0048] (2) Grind and dry the reducing material. The grinding particle size is ≤3mm, the impact depth in the liquid molten pool is 1-2m, and the moisture content after drying is ≤3wt%. (3) The gas produced by the molten reduction smelting furnace contains 1-8 vol% H2, 15-30 vol% CO, 15-30 vol% CO2, and 5-10 vol% H2O, with a temperature of 1450-1650℃. This high-temperature sensible heat is used to react the modified materials in the reforming furnace. The working temperature of the reforming furnace is 1100-1300℃, and the temperature of the gas discharged from the reforming furnace is 800-1000℃. After heat exchange, the gas temperature drops to 100-250℃. After dust removal, the dust content is ≤5mg / Nm³.

[0049] (4) The pressure of the gas after dust removal is increased to ≥400kPa. At the same time, the 1000℃ high-temperature reduction flue gas in the production system is introduced through the ejector device. The two gases are mixed in proportion by the mixing device. The temperature of the mixed carrier gas is 300℃, and the ratio and temperature are adjustable. The mixed gas is used as the carrier gas for the iron material and the reducing material and is blown into the molten reduction smelting furnace through the solid material spray gun.

[0050] The flow rate of the mixed gas is 50,000 to 8,000 Nm³ / hour per single spray gun. The iron-containing material is mineral powder, and the reducing material is pulverized coal. The ratio of mineral powder to pulverized coal is 3:1.

[0051] (5) Oxygen-enriched hot air is injected into the molten reduction furnace through three evenly distributed hot air guns in a swirling manner from the inclined top of the furnace. A vortex reaction interface is generated in the molten reduction furnace. Due to the replenishment of reducing gas and the vortex entry of oxygen-enriched hot air into the molten reduction furnace, the reaction ratio between reducing gas and oxygen is increased, and more heat is generated under the same oxygen consumption conditions, thereby reducing the reverse reaction rate in the molten reduction furnace and significantly reducing carbon consumption.

[0052] Oxygen-enriched hot air at 1200℃ is directly blown into the molten reduction smelting furnace through a hot air blast gun to provide the oxygen needed to generate heat in the combustion zone of the molten reduction smelting furnace.

[0053] The oxygen-enriched hot air has an oxygen enrichment rate of 40%. The main reactions in the molten pool of a molten reduction furnace are: Fe2O3 (l)+CO(g)→Fe (l)+CO2(g); Fe2O3 (l)+C(1)→Fe (l)+CO(g); The main reactions in the upper oxidation zone of the molten reduction furnace are: CO(g) + O2(g) → CO2(g); Through the above reactions, liquid iron and slag are generated in the molten reduction furnace, while high-temperature gas is produced simultaneously. Due to their different specific gravities, the liquid iron and slag rapidly separate vertically within the furnace. The liquid iron is discharged through the molten iron nozzle, and the slag is discharged through the slag nozzle. The liquid-liquid reaction and the unreacted reducing gas pass through the slag and reach the upper part of the molten pool in the molten reduction furnace, where they react with the oxygen-enriched hot air to generate heat, providing continuous heat for the reduction reaction in the molten pool. The unburned gas and the exhaust gas from combustion are mixed and then enter the subsequent heat exchange and dust removal devices to obtain pure gas, which can be recycled back into the molten reduction furnace as solid injection carrier gas.

[0054] like Figure 2As shown, the smelting reduction furnace includes a furnace body 1. The smelting reduction process takes place in the lower liquid slag and iron zone of the furnace body. Part of the gas generated during smelting is burned in the upper part of the furnace body to release heat, providing heat for the smelting in the lower part. Part of the gas is discharged outside the smelting reduction furnace through the exhaust port 2 along with the combustion exhaust gas. The gas discharged outside the furnace is treated and used as a solid material carrier gas to blow iron-containing materials, reducing materials, and flux into the smelting reduction furnace through the injection pipe 5. Oxygen-enriched hot air is evenly distributed to three hot air lances 4 inserted into the furnace through the annular pipe 3. The oxygen-enriched hot air is injected into the smelting reduction furnace from the inclined top of the furnace through the three evenly distributed hot air lances in a swirling manner, generating a vortex reaction interface in the smelting reduction furnace, causing the lower liquid reaction zone to surge and promoting the reaction. The molten iron produced by the reaction is discharged to the ladle through the molten iron outlet 6, and the slag is discharged to the slag granulation treatment system through the slag outlet 7 of the smelting reduction furnace.

[0055] like Figure 3 , 4 As shown, oxygen-enriched hot air is uniformly injected into the molten reduction smelting furnace through the annular pipe 3 and three hot air spray guns 4 inserted into the furnace at a clockwise angle of 70°. A vortex reaction interface is generated in the molten reduction smelting furnace, causing the liquid reaction zone at the bottom to surge and promoting the reaction.

[0056] The molten reduction short-process low-carbon smelting process completed through Example 1 reduces the overall carbon emissions per ton of iron to below 0.35 tons.

[0057] Example 2: This melt reduction short-process includes the following steps: (1) Pretreatment: The iron-containing material is preheated with reducing gas containing CO and H2 at a temperature controlled at 700±30℃. The preheated iron-containing material is then screened by a vibrating screen. Iron-containing material with a particle size <3mm is conveyed to the ore powder injection device by a bucket elevator, while iron-containing material with a particle size ≥3mm is conveyed to the silo of the hydrogen-based reduction device by another bucket elevator. For iron-containing material with a particle size ≥3mm, hydrogen-based pre-reduction is performed. High-temperature coal gas at 1000℃ after coal gas reforming in step 3) is exchanged with hydrogen-rich gas at a rate of 60000 Nm³ / h. Typical indicators of the hydrogen-rich gas are as follows: Hydrogen (H2): Approximately 80%; Carbon dioxide (CO2): 10-15%; Carbon monoxide (CO): 1-5%; Methane (CH4): 1-3%; Nitrogen (N2) or other inert gases: trace amounts.

[0058] Electric heating is used at the end of the heat exchanger to control the temperature of the hydrogen-rich gas at 1050℃. The heated hydrogen-rich gas is then transported to the bottom of the hydrogen-based reduction unit via pipeline at a rate of 40,000 Nm³ / h. Simultaneously, the iron-containing material in the hydrogen-based reduction material silo is stably transported to the upper part of the hydrogen-based reduction unit by a feeder at a feeding speed of 30 tons / hour. The iron-containing material undergoes a reduction reaction inside the hydrogen-based reduction unit. After pre-reduction, the iron-containing material is discharged by the feeder and then transported back to the ore powder injection device by a bucket elevator to be mixed with the preheated small-particle iron-containing material. The pre-reduction degree of the mixed material is about 30%.

[0059] (2) Grind and dry the reducing material. The grinding particle size is ≤3mm, the impact depth in the liquid molten pool is 1-2m, and the moisture content after drying is ≤3wt%. (3) The gas produced by the molten reduction smelting furnace contains 1-6 vol% H2, 17-28 vol% CO, 17-30 vol% CO2, and 5-8 vol% H2O, with a temperature of 1450-1650℃. This high-temperature sensible heat is used to react the modified materials in the reforming furnace. The working temperature of the reforming furnace is 1100-1300℃, and the temperature of the gas discharged from the reforming furnace is 900-1100℃. After heat exchange, the gas temperature drops to 100-250℃. After dust removal, the dust content is ≤5mg / Nm³.

[0060] (4) The pressure of the gas after dust removal is increased to ≥400kPa. At the same time, the 1000℃ high-temperature reduction flue gas in the production system is introduced through the ejector device. The two gases are mixed in proportion by the mixing device. The temperature of the mixed carrier gas is 300℃, and the ratio and temperature are adjustable. The mixed gas is used as the carrier gas for the iron material and the reducing material and is blown into the molten reduction smelting furnace through the solid material spray gun.

[0061] The flow rate of the mixed gas is 50,000 to 8,000 Nm³ / hour per single spray gun. The iron-containing material is mineral powder, and the reducing material is pulverized coal. The ratio of mineral powder to pulverized coal is 3:1.

[0062] (5) Oxygen-enriched hot air is injected into the molten reduction furnace through three evenly distributed hot air guns in a swirling manner from the inclined top of the furnace. A vortex reaction interface is generated in the molten reduction furnace. Due to the replenishment of reducing gas and the vortex entry of oxygen-enriched hot air into the molten reduction furnace, the reaction ratio between reducing gas and oxygen is increased, and more heat is generated under the same oxygen consumption conditions, thereby reducing the reverse reaction rate in the molten reduction furnace and significantly reducing carbon consumption.

[0063] Oxygen-enriched hot air at 1200℃ is directly blown into the molten reduction smelting furnace through a hot air blast gun to provide the oxygen needed to generate heat in the combustion zone of the molten reduction smelting furnace.

[0064] The oxygen-enriched hot air has an oxygen enrichment rate of 40%. The main reactions in the molten pool of a molten reduction furnace are: Fe2O3 (l)+CO(g)→Fe (l)+CO2(g); Fe2O3 (l)+C(1)→Fe (l)+CO(g); The main reactions in the upper oxidation zone of the molten reduction furnace are: CO(g) + O2(g) → CO2(g); Through the above reactions, liquid iron and slag are generated in the molten reduction furnace, while high-temperature gas is produced simultaneously. Due to their different specific gravities, the liquid iron and slag rapidly separate vertically within the furnace. The liquid iron is discharged through the molten iron nozzle, and the slag is discharged through the slag nozzle. The liquid-liquid reaction and the unreacted reducing gas pass through the slag and reach the upper part of the molten pool in the molten reduction furnace, where they react with the oxygen-enriched hot air to generate heat, providing continuous heat for the reduction reaction in the molten pool. The unburned gas and the exhaust gas from combustion are mixed and then enter the subsequent heat exchange and dust removal devices to obtain pure gas, which can be recycled back into the molten reduction furnace as solid injection carrier gas.

[0065] like Figure 2 As shown, the smelting reduction furnace includes a furnace body 1. The smelting reduction process takes place in the lower liquid slag and iron zone of the furnace body. Part of the gas generated during smelting is burned in the upper part of the furnace body to release heat, providing heat for the smelting in the lower part. Part of the gas is discharged outside the smelting reduction furnace through the exhaust port 2 along with the combustion exhaust gas. The gas discharged outside the furnace is treated and used as a solid material carrier gas to blow iron-containing materials, reducing materials, and flux into the smelting reduction furnace through the injection pipe 5. Oxygen-enriched hot air is evenly distributed to three hot air lances 4 inserted into the furnace through the annular pipe 3. The oxygen-enriched hot air is injected into the smelting reduction furnace from the inclined top of the furnace through the three evenly distributed hot air lances in a swirling manner, generating a vortex reaction interface in the smelting reduction furnace, causing the lower liquid reaction zone to surge and promoting the reaction. The molten iron produced by the reaction is discharged to the ladle through the molten iron outlet 6, and the slag is discharged to the slag granulation treatment system through the slag outlet 7 of the smelting reduction furnace.

[0066] like Figure 3 , 4 As shown, oxygen-enriched hot air is uniformly injected into the molten reduction smelting furnace through the annular pipe 3 and three hot air spray guns 4 inserted into the furnace at a clockwise angle of 55°. This generates a vortex reaction interface in the molten reduction smelting furnace, causing the liquid reaction zone at the bottom to surge and promoting the reaction.

[0067] The molten reduction short-process low-carbon smelting process completed through Example 2 above reduces the overall carbon emissions per ton of iron to below 0.40 tons.

Claims

1. A green, low-carbon, short-process smelting reduction process, characterized in that, Includes the following steps: 1) The iron-containing material is screened into fine iron-containing material and coarse iron-containing material; the fine iron-containing material is fed into a mineral powder injection device; the coarse iron-containing material is fed into a hydrogen-based reduction device, where it undergoes hydrogen-based pre-reduction using hydrogen or hydrogen-rich gas heated by a gas reforming device, and then mixed with the fine iron-containing material to form an iron-containing mixture, wherein the particle size of the fine iron-containing material is <3mm, the particle size of the coarse iron-containing material is ≥3mm, and the hydrogen-based pre-reduction temperature is 850°C. 1300℃; 2) Grind and dry the reducing material to obtain reducing powder. The particle size of the reducing powder is ≤3mm and the moisture content is ≤3wt%. 3) 1450 kWh discharged from the molten reduction furnace High-temperature coal gas at 1650℃ and pressure ≤100kPa is divided into three streams. The first stream is fed into a coal gas reforming unit, where the sensible heat of the high-temperature coal gas reacts with the reforming materials to obtain reformed coal gas. The reformed coal gas is then fed into a hydrogen-based heating unit to exchange heat with the hydrogen-based gas and raise its temperature. After that, it is processed by a No. 2 heat exchanger and a dust removal unit to obtain clean coal gas. The second stream of high-temperature coal gas is directly fed into a No. 1 heat exchanger. The gas output from the No. 1 heat exchanger is connected to the No. 2 heat exchanger, where it merges with the gas from the first stream to complete heat exchange and cooling. The third stream of high-temperature coal gas is directly used as the low-speed inlet gas for the ejector device. A portion of the clean coal gas output from the dust removal unit is pressurized to obtain high-pressure clean coal gas with a pressure ≥400kPa. 4) A portion of the high-pressure purified coal gas is used as the injection carrier gas for the reducing powder, injecting the reducing powder into the molten iron bath of the molten reduction furnace; another portion of the high-pressure purified coal gas is used as the ejector gas to eject the high-temperature coal gas, resulting in a temperature of 200°C after ejection. 1200℃, pressure ≥400kPa, blowing speed 30 A 60 m / s mixed ejector gas is used as the injection carrier gas for the iron-containing mixture, which is injected into the iron bath pool of the molten reduction furnace. The coal gas and reducing powder injected into the iron bath pool as carrier gas simultaneously undergo a reduction reaction with the iron-containing material. The impact depth of the reducing powder and the iron-containing mixture injected into the iron bath pool is 1 to 2 m. 5) During the molten reduction process, oxygen-enriched hot air is injected into the furnace shoulder of the molten reduction smelting furnace through a hot air spray gun in a swirling manner. The tilt angle of the hot air spray gun (4) is 55-85° with the liquid surface in the furnace, so that a vortex reaction interface is generated in the furnace, increasing the reaction ratio of reducing gas and oxygen, and reducing the reverse reaction rate in the furnace.

2. The green, low-carbon smelting reduction short-process smelting process according to claim 1, characterized in that: In step 1), the iron-containing material is preheated before being screened, with the preheating temperature controlled between 30 and 1000°C.

3. A green, low-carbon, short-process smelting system for melting reduction applied to the process described in any one of claims 1-2, characterized in that: The system includes a molten reduction smelting furnace, a gas reforming unit, a hydrogen-based heating unit, a No. 1 heat exchanger, a No. 2 heat exchanger, a dust removal unit, a gas pressurizing unit, an ejector unit, a processing unit, a pulverized coal injection unit, a screening unit, a hydrogen-based reduction unit, a mineral powder injection unit, a blower unit, a hot blast stove, and a hot blast injection unit. The molten reduction smelting furnace is equipped with a injection pipe extending into the molten iron bath. The inlet of the processing unit is connected to the reducing material supply source, and the outlet is connected to the pulverized coal injection unit; the outlet of the pulverized coal injection unit is connected to the injection pipe. The inlet of the screening unit is connected to the iron-containing material supply source. The coarse material outlet is connected to the hydrogen-based reduction unit; the outlet of the hydrogen-based reduction unit and the fine material outlet of the screening unit are connected to the ore powder injection unit; the outlet of the ore powder injection unit is connected to the injection pipe. The high-temperature gas outlet of the molten reduction smelting furnace is divided into three paths. One path is connected in sequence to the gas reforming unit, the hydrogen-based heating unit, the No. 2 heat exchange unit, and the dust removal unit. The outlet of the dust removal unit is connected to the gas pressurizing unit. The outlet of the gas pressurizing unit is connected to the outlet of the ore powder injection unit, serving as the injection carrier gas for the reduced powder in the ore powder injection unit. The other path is connected to the high-speed flow inlet of the ejector device. The high-temperature gas outlet of the molten reduction smelting furnace is connected to the low-speed flow inlet of the ejector device, and the outlet of the ejector device is connected to the outlet of the ore powder injection device, serving as the injection carrier gas for the iron-containing mixture in the ore powder injection device; the high-temperature gas outlet of the molten reduction smelting furnace is connected to the No. 2 heat exchanger through the No. 1 heat exchanger; the hydrogen-based gas inlet of the hydrogen-based heating device is connected to a hydrogen or hydrogen-rich supply source, and the hydrogen-based gas outlet is connected to the hydrogen-based reduction device; the outlet of the blower device is connected to the inlet of the hot blast stove, and the outlet of the hot blast stove is connected to the inlet of the hot blast injection device; the hot blast injection device is equipped with a hot blast nozzle (4), and there is at least one hot blast nozzle (4), which extends into the furnace from the furnace shoulder of the molten reduction smelting furnace at a clockwise or counterclockwise angle.

4. The green, low-carbon smelting reduction short-process smelting system according to claim 3, characterized in that: The molten reduction smelting furnace is equipped with two molten iron outlets (6).

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