CN117646095A - Zero-oxygen blowing low-carbon ironmaking method - Google Patents
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- CN117646095A CN117646095A CN202311368828.8A CN202311368828A CN117646095A CN 117646095 A CN117646095 A CN 117646095A CN 202311368828 A CN202311368828 A CN 202311368828A CN 117646095 A CN117646095 A CN 117646095A
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- 238000007664 blowing Methods 0.000 title claims abstract description 38
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Abstract
The invention relates to a zero-oxygen blowing low-carbon iron-making method, and belongs to the technical field of non-blast furnace low-carbon metallurgy. The method comprises the following steps: filling hot self-fluxing oxidized pellets into a gas-based shaft furnace from the top of the gas-based shaft furnace, spraying cold reducing gas into the gas-based shaft furnace from the bottom of the gas-based shaft furnace, and simultaneously spraying hot reducing gas into the gas-based shaft furnace from the junction of a reduction section and a cooling section of the gas-based shaft furnace, wherein the cold reducing gas is heated in the rising process and mixed with the hot reducing gas, and then is subjected to pre-reduction reaction with the self-fluxing oxidized pellets to obtain hot direct reduced iron, and the hot direct reduced iron is cooled by the cold reducing gas in the cooling section to obtain direct reduced iron; and (3) loading solid carbon materials and direct reduced iron from the top of the zero-oxygen injection furnace, injecting super-heated reducing gas into the zero-oxygen injection furnace, and reducing and melting the direct reduced iron to obtain liquid slag and molten iron. The invention reduces the gas heating energy consumption, and compared with a blast furnace, the invention obviously reduces the carbon emission.
Description
Technical Field
The invention belongs to the technical field of non-blast furnace low-carbon metallurgy, and particularly relates to a zero-oxygen blowing low-carbon iron-making method.
Background
The prior art mature iron-making process mainly comprises blast furnace iron-making, smelting reduction (HIsmelt, COREX, finex), direct reduction (gas-based direct reduction, coal-based direct reduction) and the like, and the prior art has advantages and disadvantages, and mainly comprises the following steps:
1. the blast furnace ironmaking process technology is mature, the annual capacity of single-seat equipment can be up to more than million tons, but the disadvantage is that the high-quality metallurgical coke is excessively depended on, and the average solid fuel unit consumption in industry is 0.55kg/t Molten iron The method comprises the steps of carrying out a first treatment on the surface of the The coking, sintering and pelletizing are required to be matched and constructed, and the system investment is large; the operation difficulty of the blast furnace is high, and the recovery is difficult after the abnormality and fluctuation of the furnace condition; high cost, carbon emission, high energy consumption, etc.
2. Melt reduction
(1) The heat transfer effect of the HIsmolt process is poor, the molten iron temperature of a molten pool is lower by 1400-1450 ℃, and the smoke flow rate is up to 2700Nm 3 The temperature of the iron/t and the flue gas reaches 1600 ℃, and a large amount of physical heat is removed from the furnace along with the flue gas; high iron loss, high fuel consumption and high carbon emission.
(2) The content of COREX and Finex molten iron [ Si ] is high, the gas generation amount is overlarge, and the primary carbon consumption is high.
(3) The chemical energy utilization rate of carbon is insufficient, and part of carbon element escapes along with the gas in the form of CO, so that the chemical energy cannot be further utilized.
3. Direct reduction
The direct reduction process is a process of smelting iron ore into iron by solid state reduction at a temperature lower than the melting temperature of the ore, and the iron produced by this process is called Direct Reduced Iron (DRI). Depending on the reducing agent, two main classes are gas-based direct reduction and coal-based direct reduction. Among them, the gas-based reduction process is the mainstream in the global world, and is dominant.
The direct reduction of the coal base needs solid fuel, so that the carbon consumption is high, and the problem of reducing carbon emission in iron making cannot be solved by the direct reduction of the coal base from the perspective of green low-carbon development in the steel industry, and the requirement on ore quality is higher.
The gas-based shaft furnace is the current process flow with the maximum carbon reduction potential and accounts for 75.3 percent of the total direct reduction yield (wherein MIDREX accounts for 60.0 percent, HYL accounts for 12.4 percent and PERED accounts for 2.9 percent), but the prior gas-based shaft furnace process has the following defects:
(1) High raw material cost and great popularization difficulty: the existing gas-based shaft furnace technology adopts an electric furnace to deeply melt and separate direct reduced iron, which requires pellet TFe to be more than 67 percent and SiO to be treated 2 Less than 3.0 percent, if no high-grade pellets are ensured, the amount of the electric furnace slag is large in the subsequent electric furnace smelting. Because the electric furnace production process is not like a blast furnace in a large amount of gas blowing and stirring, the dynamic condition of the production process is poor, the slag quantity is increased, so that the heat transfer is slow, the production efficiency of the electric furnace is low, the smelting period is long, the energy consumption is high, and the cost is high. In China, iron ores mainly comprise lean ores, and the current gas-based shaft furnace has severe requirements on raw material ores, so that not only is the raw material purchasing cost high, but also the gas-based shaft furnace is difficult to popularize in China.
(2) The gas making cost is high and the safety risk is high. The existing gas-based shaft furnace adopts pellets to be cold-charged into the shaft furnace, heat required by the reaction in the furnace is brought in through heated reducing gas, and in order to enlarge a high-temperature region of 600-1100 ℃ in the furnace, higher gas temperature and larger gas quantity are required. On the other hand, in order to prevent the produced sponge iron from sticking in the furnace, the furnace H must be controlled 2 CO volume ratio is greater than 1:1, the upper limit of the temperature of the reducing gas is controlled to be less than 1100 ℃, due to H 2 The reduced iron oxide is an endothermic reaction, which increases the temperature drop in the furnace and requires a greater amount of gas. Due to H 2 The cost is higher than that of CO and H 2 The high-temperature heating cost of the gas-based shaft furnace is high, the power cost of circulating and pressurizing a large amount of gas in the system is high, and the high-temperature heating cost is one of the reasons of high cost and high safety risk of the gas-based shaft furnace.
(3) The gas-based shaft furnace-electric furnace melting separation process has low operation efficiency and large scale difficulty. The high gas quantity, high temperature and high hydrogen content of the shaft furnace cause 20 days of furnace shutdown for a year, and all pipelines are inspected; the continuous charging and continuous slag tapping of the electric furnace have great difficulty, the large-scale furnace capacity of the electric furnace has difficulty, the reaction rate of the electric furnace is slow, and the like.
In summary, the operation cost of the existing gas-based shaft furnace is 600 yuan/ton higher than that of the blast furnace ironmaking, and the operation cost is further reduced to about 1000 yuan/ton higher than that of the electric furnace steel. Therefore, the development of the gas-based direct reduction process flow which is suitable for the characteristics of Chinese iron ore and energy sources and has low cost, safety and high efficiency has a very positive effect on the promotion of the steel industry in China.
Disclosure of Invention
Aiming at the problems, the invention provides a zero oxygen injection low-carbon ironmaking method, which adopts self-fluxing pellets to be hot filled into a gas-based shaft furnace, gas in a cooling section of the gas-based shaft furnace enters a reduction section as a reducing agent, and a part of hot reducing gas is supplemented in the reduction section of the shaft furnace to obtain cold Direct Reduced Iron (DRI) with a metallization rate of more than 92 percent. DRI and solid carbon materials are added through the top of a zero-oxygen injection furnace, the furnace hearth of the zero-oxygen injection furnace is injected with super-heated reducing gas, the DRI is further reduced and heated in the zero-oxygen injection furnace to generate high-temperature molten iron and slag, and the high-temperature molten iron and slag are discharged out of the furnace from a slag iron notch. The heat of gas products generated in the gas-based shaft furnace and the zero-oxygen injection furnace is recovered by a heat exchanger, so that dust and CO are further removed 2 、H 2 And O is recycled as a gas reducing agent of the system. The heating temperature and heating quantity of the reducing gas of the gas-based shaft furnace can be effectively reduced, the cost and energy consumption of deep reduction and fusion separation are reduced, and the operation rate of the system is improved.
A first object of the present invention is to provide a zero oxygen injection low carbon ironmaking method, the method comprising:
filling hot self-fluxing oxidized pellets into a gas-based shaft furnace from the top of the gas-based shaft furnace, spraying cold reducing gas into the gas-based shaft furnace from the bottom of the gas-based shaft furnace, and simultaneously spraying hot reducing gas into the gas-based shaft furnace from the junction of a reduction section and a cooling section of the gas-based shaft furnace, wherein the cold reducing gas is heated in the rising process and mixed with the hot reducing gas, and then is subjected to pre-reduction reaction with the self-fluxing oxidized pellets to obtain hot direct reduced iron, and the hot direct reduced iron is cooled by the cold reducing gas in the cooling section to obtain direct reduced iron;
The solid carbon material and the direct reduced iron are mixed according to massThe ratio is (0.03-0.1): 1, charging from the top of a zero oxygen injection furnace, and charging the furnace at a temperature of 1800-2350 ℃ and a flow rate of 900-1500 Nm 3 And (3) injecting the super-heated reducing gas of ton of ferrite into a zero-oxygen injection furnace, and reducing and melting the direct reduced iron to obtain liquid slag and molten iron.
When the hot self-fluxing oxidized pellet ore is loaded into the gas-based shaft furnace, the temperature is 600-1100 ℃; the self-fluxing oxidized pellet is obtained by high-temperature treatment of iron ore, flux and bentonite, wherein the high-temperature treatment is a treatment means well known in the technical field, and the embodiment of the invention is not repeated here; the high temperature treatment does not involve cooling of the self-fluxing oxidized pellets; the temperature of the self-fluxing oxidized pellet is 6001100 ℃, is generated in a high-temperature treatment process, and is not generated by secondary heating;
further, when a flux (CaCO as a main component) is added to a gas-based shaft furnace or a zero-oxygen injection furnace 3 ) Will cause CaCO 3 The decomposition absorbs heat to influence the system temperature and the reaction speed, so that the pellets need to adopt self-fluxing pellets, and the self-fluxing oxidized pellets contain CaO, siO 2 The mass ratio is 0.9-1.3, and the mass ratio of Fe element in the pellet is 50-69%.
Further, the mass ratio of Fe element in the self-fluxing oxidized pellet is 50-69%; the temperature of the obtained direct reduced iron after the hot direct reduced iron is cooled by the cold reducing gas in the cooling section is less than 250 ℃, and the metallization rate is more than or equal to 92%; the solid carbon material is any one or more of coke, semi-coke and formed coke, and the fixed carbon content in the solid carbon material is more than 75%; the cold reducing gas temperature is less than 50 ℃.
Further, the hot reducing gas and the super-hot reducing gas are reducing gas of a reducing gas cabinet, and the cold reducing gas is reducing gas of the reducing gas cabinet and/or coke oven gas;
the reducing gas of the reducing gas cabinet comprises purified gas and new supplementary reducing gas, and the reducing gas of the reducing gas cabinet comprises CO and H as the gas components 2 、N 2 And impurity gases, and CO and H 2 The sum of the volume percentages is more than 92%;
the purified gas is gas obtained by recovering heat energy from top gas of a gas-based shaft furnace and a zero-oxygen injection furnace through heat exchange and purifying;
the hot reducing gas, namely, the gas heated to the required temperature after the part of the reducing gas in the reducing gas cabinet is pressurized is preheated by a heat exchange system;
the super-heated reducing gas, namely the other part of gas in the reducing gas cabinet, is preheated by a heat exchange system after being pressurized, and then is heated to the gas with the required temperature.
Further, the total flow of the gas in the gas-based shaft furnace comprises cold reduction gas flow and hot reduction gas flow, wherein the ratio of the cold reduction gas flow to the hot reduction gas flow is K;
when injecting reducing gas H into gas-based shaft furnace 2 When CO is more than 5, the charging temperature of the self-fluxing oxidized pellet ore is 1050-1100 ℃, and the total flow of the reducing gas in the gas-based shaft furnace is 1800-1900 Nm 3 The value range of K is 1.7-2.1, and the temperature of hot reducing gas is 1050+/-20 ℃;
when the reducing gas is injected into the gas-based shaft furnace, the H is less than 1.5 2 When CO is less than or equal to 5, the charging temperature of the self-fluxing oxidized pellet ore is 1000-1050 ℃, and the total flow rate of the reducing gas in the gas-based shaft furnace is 1900-2000 Nm 3 The value range of K is 1.5-1.8, and the temperature of hot reducing gas is 1000-1050 ℃;
when the reducing gas is injected into the gas-based shaft furnace, H is more than 0.6 and less than H 2 When CO is less than or equal to 1.5, the charging temperature of the self-fluxing oxidized pellet ore is 950-1000 ℃, and the total flow of the reducing gas in the gas-based shaft furnace is 2000-2100 Nm 3 The value range of K is 1.3-1.6, and the temperature of hot reducing gas is 980+/-20 ℃;
when the reducing gas is less than 0.2 and less than H in the gas-based shaft furnace 2 When CO is less than or equal to 0.6, the charging temperature of the self-fluxing oxidized pellet ore is 900-950 ℃, and the total flow of the reducing gas in the gas-based shaft furnace is 2100-2200 Nm 3 The value range of K is 1.2-1.4, and the temperature of hot reducing gas is 950+/-20 ℃;
when injecting reducing gas H into gas-based shaft furnace 2 When CO is less than or equal to 0.2, the charging temperature of the self-fluxing oxidized pellet ore is 880-920 ℃, and the gas-based vertical furnace is used for the production of the self-fluxing oxidized pellet oreThe total flow of the reducing gas in the furnace is 2200-2300 Nm 3 The value range of the ferrite/t and the K is 1.1-1.3, and the temperature of the hot reducing gas is 930+/-20 ℃.
In the descending process of the thermal self-fluxing oxidized pellets in the gas-based shaft furnace, the thermal reducing gas in the gas-based shaft furnace is contacted with the gas formed by mixing the heated cold reducing gas, and the thermal self-fluxing oxidized pellets undergo a reduction reaction with the gas formed by mixing the heated cold reducing gas in the gas-based shaft furnace: fe (Fe) 2 O 3 +CO→Fe 3 O 4 +CO 2 、Fe 3 O 4 +CO→FeO+CO 2 、FeO+CO→Fe+CO 2 And reacting: fe (Fe) 2 O 3 +H 2 →Fe 3 O 4 +H 2 O (gas), fe 3 O 4 +H 2 →FeO+H 2 O (gas), feO+H 2 →Fe+H 2 O (gas) to form hot solid Direct Reduced Iron (DRI), gaseous CO 2 And H 2 O, the process is called as pre-reduction of self-fluxing oxidized pellets, and the product after pre-reduction of the self-fluxing oxidized pellets is called as DRI (direct reduced iron);
thereafter, the hot DRI continues to descend and meet the ascending cold reducing gas and heat exchange occurs such that the cold reducing gas temperature rises and the hot DRI temperature falls and the reaction occurs: feO+H 2 →Fe+H 2 O (gas), feO+CO→Fe+CO 2 And/or CH 4 ＝C+H 2 And/or c+3fe=fe 3 C, obtaining cold DRI, and simultaneously, raising the temperature of cold reducing gas, continuously mixing with hot reducing gas, and contacting with self-fluxing oxidized pellets to reduce the self-fluxing oxidized pellets;
finally, discharging cold DRI from a discharge hole at the bottom of the gas-based shaft furnace, and sequentially downwards moving furnace burden at the upper part of the gas-based shaft furnace; wherein, the gas generated by chemical reaction in the gas-based shaft furnace and the reducing gas which does not generate chemical reaction are jointly called shaft furnace gas, and the shaft furnace gas is output from a shaft furnace top gas delivery pipe.
Further, the control ranges of the furnace inlet flow and the furnace inlet temperature of the super-heated reducing gas sprayed into the zero-oxygen spraying furnace are specifically as follows:
when the flow rate of the super-heated reducing gas blown into the furnace is 900-1200 Nm 3 When per ton of ferrite, the temperature of the super-heated reducing gas entering the furnace is controlledAt 2130-2320 ℃;
when the flow rate of the super-heated reducing gas blown into the furnace is 1200-1500 Nm 3 When per ton of ferrite, the temperature of the super-heated reducing gas entering the furnace is controlled to 1850-2250 ℃.
In the zero-oxygen injection furnace, the solid carbon material is contacted with direct reduced iron and reducing gas, wherein the direct reduced iron is deeply reduced to obtain molten iron and slag; the gas generated by chemical reaction in the zero-oxygen injection furnace and the reducing gas which does not generate chemical reaction are collectively called as zero-oxygen injection furnace gas, and the zero-oxygen injection furnace gas is output from a zero-oxygen injection furnace gas delivery pipe at the top of the zero-oxygen injection furnace.
The second object of the invention is to provide a zero-oxygen injection low-carbon ironmaking device, which realizes the above-mentioned zero-oxygen injection low-carbon ironmaking method, comprising a gas-based shaft furnace and a zero-oxygen injection furnace;
the gas-based shaft furnace is divided into a reduction section and a cooling section from top to bottom along the vertical direction inside;
a plurality of hot reducing gas injection ports are symmetrically arranged on the same horizontal section at the junction of the reducing section and the cooling section, and the reducing section is used for the pre-reduction reaction of the self-fluxing oxidized pellets to obtain hot direct reduced iron;
A plurality of cold reducing gas injection ports are symmetrically arranged on the same horizontal section in the lower part of the cooling section, and the cooling section is used for cooling hot direct reduced iron to obtain cold direct reduced iron;
the direct reduced iron discharged from the bottom of the cooling section is transported to the zero-oxygen injection furnace, the zero-oxygen injection furnace is a non-electric furnace and a non-blast furnace, the oxygen injection amount is zero, the inside of the zero-oxygen injection furnace is divided into a furnace body and a furnace hearth from top to bottom along the vertical central line of the zero-oxygen injection furnace, and the zero-oxygen injection furnace is used for reducing and melting the direct reduced iron to obtain liquid slag and molten iron.
Further, the vertical direction inside the furnace body is divided into a solid material layer and a soft molten drop zone from top to bottom; the vertical direction inside the hearth is divided into a gas whirling region, a slag layer and a molten iron layer from top to bottom.
Further, the hearth is positioned on the same horizontal section of the gas swirling zone, a plurality of reducing gas injection openings are symmetrically distributed along the circumference, the hearth is positioned on the same horizontal section of the liquid slag layer, a plurality of slag outlets are symmetrically distributed along the circumference, the hearth is positioned on the same horizontal section of the liquid iron water layer, and a plurality of tapping holes are symmetrically distributed along the circumference.
Further, the diameter of the zero oxygen injection furnace hearth adopts an adjustable loop design, and the diameter of the zero oxygen injection furnace hearth and the flow rate of the injected super-heated reducing gas are controlled as follows:
when the diameter d of the hearth is less than 10m, the flow rate of the injected super-heated reducing gas is 150-350 m/s;
when the diameter d of the hearth is more than 10m, the flow rate of the injected super-heated reducing gas is 250-450 m/s.
Further, the ratio of the inner diameter of the horizontal section of the lower part of the reduction section of the gas-based shaft furnace to the diameter of the hearth of the zero-oxygen injection furnace is 1.0-1.3; the height of the material layer in the reduction section of the gas-based shaft furnace is 5-8 meters; the ratio of the hearth height of the zero-oxygen injection furnace to the hearth diameter of the zero-oxygen injection furnace is 0.35-0.6, and the ratio of the hearth height of the zero-oxygen injection furnace to the hearth diameter of the zero-oxygen injection furnace is 0.8-1.3.
The invention has the beneficial effects that:
(1) The invention adopts self-fluxing oxidized pellet ore to be thermally loaded into the gas-based shaft furnace, so that the ore in the furnace is in a high temperature area, namely the reaction area is enlarged, the metallization rate is improved, the gas heating temperature is reduced or/and the flow of heated gas is reduced, and the reduction of energy consumption is realized.
(2) The technology adopts cold reducing gas, enters a shaft furnace reduction section after heat exchange and temperature rise with hot DRI, and participates in the pre-reduction reaction of self-fluxing oxidized pellets, and the beneficial effects of the design are as follows: on one hand, the total gas flow of the reducing gas and the cooling gas of the gas-based shaft furnace is reduced, the power cost of gas transportation is reduced, and on the other hand, the cold reducing gas is used as a carrier to transfer the physical heat of hot DRI to the reduction section of the gas-based shaft furnace, so that the physical heat of the DRI is recycled, and the energy consumption of the system is further reduced.
(3) The invention is not limited by air sourcePreparing the H in the reducing gas component 2 CO is low in requirement and applicable to any H 2 Reducing gas of CO. In the existing gas-based shaft furnace process, because of the mass and heat transfer modes of hot gas, cold ore, upper cold and lower heat, in the gas-based shaft furnace, when the pellet ore is lowered to the middle lower part of a reduction section, the metallization rate is increased to more than 80%, in order to prevent the pellet ore from being bonded at high temperature and high metallization rate, the shaft furnace cannot smoothly discharge, and at the moment, the reducing gas H must be controlled 2 CO is more than 1.2. The gas-based shaft furnace is hot ore medium-temperature gas, upper heat and lower cool, when the self-fluxing oxidized pellet ore is reduced to the middle lower part of the reduction section and the metallization rate is increased to more than 80 percent, the pellet temperature is reduced to below 800 ℃, the temperature of the mixed gas formed by the cold reducing gas and the hot reducing gas is far lower than that of the prior gas-based shaft furnace process, only the flow and the temperature of the hot reducing gas are controlled according to the parameters of the claims, and the test result shows that even in the reducing gas H 2 Under the condition that CO tends to 0, the production disorder of the shaft furnace caused by pellet adhesion can be effectively avoided.
(4) The process adopts a zero-oxygen injection furnace to replace an electric furnace, and realizes the deep reduction of DRI and the melting separation of slag iron. The beneficial effects are as follows:
Compared with the deep reduction melt of a gas-based shaft furnace and an electric furnace, the method has the beneficial effects that: (1) and consumable materials such as electrodes and the like have low cost. The zero oxygen blowing furnace is a non-electric furnace, electrodes do not need to be inserted, and the cost caused by electrode consumption in the production process is avoided. (2) The zero oxygen injection furnace has higher thermal efficiency. The zero oxygen blowing furnace takes super-heated reducing gas as a carrier, heat is brought into the furnace from a furnace hearth reducing gas blowing opening, the blowing opening is positioned below the solid material layer and the soft melting dropping area, namely, the heat transfer mode in the zero oxygen blowing furnace is that a heat source is arranged below and a heated material is arranged above. The electric furnace is inserted with electrodes from above, and the heating mode is upper heating. Therefore, the zero oxygen injection furnace has higher thermal efficiency. (3) The zero-oxygen injection furnace is suitable for smelting high, medium and low grade ores. The electric furnace is generally free from gas injection or has little gas injection, the heat transfer in the furnace is extremely uneven, particularly when low-grade ore is smelted, the slag quantity is large, the heat conductivity coefficient of the slag is low, the heat transfer of a molten pool is slow, the heat is uneven, and finally the electric consumption and the yield are high, so the current method is characterized in thatThe gas-based shaft furnace-electric furnace melting separation process is not suitable for smelting middle-low grade iron ore. The super-heated reducing gas injection quantity of the zero-oxygen injection furnace is 900-1500 Nm 3 The larger the diameter of the hearth, the higher the gas flow velocity, and even if low-grade ore is smelted, the strong airflow stirring can realize rapid and full reaction of slag iron, and the slag iron drops to the hearth for further separation. (4) The metal recovery rate of the zero-oxygen blowing furnace is high. The DRI reduction process in the zero oxygen blowing furnace is mainly carried out in a solid material layer, a soft melting drop zone and a convolution zone, and the slag-iron separation process is carried out in a slag layer and an iron water layer. The jetting port is arranged in the convolution region, and the upper reduction reaction is promoted to be rapidly and fully carried out under the stirring effect of the reducing gas in the upward process of the sprayed reducing gas. The sprayed reducing gas does not pass through the slag iron layer, so that the slag iron liquid of the product is in a relatively 'standing' state, and the slag iron layering and separation are more facilitated. Therefore, the metal recovery rate is more improved. (5) The zero-oxygen injection furnace is suitable for smelting special ores. When smelting refractory and difficultly-separated ore seeds, such as vanadium titano-magnetite, the dynamics condition of the zero-oxygen injection furnace is good, the DRI rapid reduction and the slag iron rapid separation and discharge can be realized, and the foam slag is avoided. In contrast, when the gas-based shaft furnace-electric furnace melting and separating process is used for smelting vanadium-titanium ore, the rapid separation and discharge of slag and iron cannot be realized in the electric furnace, so that foam slag cannot be generated, and slag and iron cannot be discharged normally. (6) The zero oxygen blowing furnace adopts continuous charging and continuous slag tapping operation, and the furnace capacity can be enlarged to 5000m 3 And above, the annual output of a single device can realize the scale of more than 350 ten thousand tons of molten iron, and the method has better popularization and application values.
Compared with a blast furnace, the beneficial effects of the furnace are as follows: (1) the carbon emissions are significantly reduced. Traditional blast furnace tuyere O 2 The blowing amount is 350-370Nm 3 Per ton of molten iron, blown-in O 2 Burning with solid carbon at the tuyere to generate high-temperature CO, O 2 The higher the blowing amount, the higher the carbon consumption and the carbon emission. The zero-oxygen injection furnace is a non-blast furnace, the oxygen injection amount is zero, the zero-oxygen injection furnace recycles CO at the top of the furnace, and the zero-oxygen injection furnace is real CO 2 The discharge amount is zero. (2) The temperature in the zero oxygen injection furnace is controlled by the super-heated reducing gas temperature of the injection port, the injection port is positioned on the furnace hearth, and the heat of the furnace hearth can be quickly and flexibly adjusted. The heat of the blast furnace hearth is burnt by each ton of furnace burdenThe amount of the solid carbon is determined, the heat regulation of the hearth is realized by adjusting the coke loading amount at the top of the hearth or the pulverized coal blowing amount at the air port, the regulation result is delayed by about 2-5 hours, the regulation process is influenced by the discharge of slag iron, and the temperature of the hearth is easy to be uncontrolled. (3) Is favorable for smelting special ore types such as vanadium titano-magnetite and the like. N in the blowing gas of the zero-oxygen blowing furnace 2 The content is less than 8 percent (the traditional blast furnace is 79 percent), the consumption of solid carbon materials is less than 0.1kg/t molten iron (the blast furnace is 0.55 kg/t) Molten iron ) The zero-oxygen injection furnace can effectively inhibit Ti (C, N) generation in the vanadium-titanium ore smelting process, and can reduce the low furnace temperature frequency due to rapid and flexible hearth temperature adjustment, thereby being beneficial to vanadium element recovery.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the following description will briefly explain the drawings used in the embodiments or the description of the prior art, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 shows a schematic structural diagram of a zero oxygen injection low carbon ironmaking apparatus according to an embodiment of the present invention;
in the figure:
10. a gas-based shaft furnace; 11. a reduction section; 12. a cooling section; 13. a shaft furnace charging assembly; 14. a cold reducing gas injection port; 15. a discharge port; 16. a hot reducing gas injection port; 17. a shaft furnace gas delivery pipe; 18. a first gravity dust collector; 20. a zero oxygen injection furnace; 21. a solid material layer; 22. a soft melt drip zone; 23. a gas swirling zone; 24. a slag layer; 25. a layer of iron water; 26. a zero oxygen injection furnace charging assembly; 27. a slag outlet; 28. a tap hole; 29. zero oxygen injection furnace gas delivery pipe; 210. reducing gas injection port of zero oxygen injection furnace; 211. a second gravity dust collector; 30. a reduction gas cabinet; 31. a first pressurizing machine; 32. a first heat exchanger; 40. a first heating furnace; 50. a second pressurizing machine; 51. a second heat exchanger; 60. a second heating furnace; 70. a gas purification system.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, a zero oxygen injection low carbon ironmaking apparatus according to an embodiment of the present invention includes a gas-based shaft furnace 10 and a zero oxygen injection furnace 20;
the gas-based shaft furnace 10 is divided into a reduction section 11 and a cooling section 12 from top to bottom along the vertical direction inside;
a plurality of hot reducing gas injection ports 16 are symmetrically arranged on the same horizontal section at the juncture of the reducing section 11 and the cooling section 12, and the reducing section 11 is used for the pre-reduction reaction of the self-fluxing oxidized pellets to obtain hot direct reduced iron;
a plurality of cold reducing gas injection ports 14 are symmetrically arranged on the same horizontal section of the lower part of the cooling section 12, the cooling section 12 is used for cooling hot direct reduced iron to obtain cold direct reduced iron, and in the embodiment of the invention, the height of the cold reducing gas injection ports 14 from the bottom of the cooling section 12 is 0.5-2.5 m;
The cold direct reduced iron discharged from the bottom of the cooling section 12 is transported to the zero-oxygen injection furnace 20, the zero-oxygen injection furnace 20 is a non-electric furnace, no electrode is needed to be inserted, the non-blast furnace is used, the oxygen injection amount is zero, the zero-oxygen injection furnace 20 is divided into a furnace body and a furnace hearth from top to bottom in the vertical direction, and the zero-oxygen injection furnace 20 is used for reducing and melting the direct reduced iron to obtain liquid slag and molten iron.
In the embodiment of the present invention, the cooling section 12 adopts an inverted truncated cone design, and the diameter of the lower section is smaller than that of the upper section.
In the embodiment of the invention, a discharge port 15 is arranged at the bottom of the cooling section 12, the cold direct reduced iron is discharged from the discharge port 15, and the position of the discharge port 15 is located below the cold reducing gas injection port 14.
In the embodiment of the present invention, for convenience of charging, the top of the gas-based shaft furnace 10 is provided with a shaft furnace charging assembly 13, the top of the zero-oxygen injection furnace 20 is provided with a zero-oxygen injection furnace charging assembly 26, and the shaft furnace charging assembly 13 and the zero-oxygen injection furnace charging assembly 26 are devices well known to those skilled in the art, and the disclosure of the present invention is not repeated herein.
In the embodiment of the invention, in order to facilitate the discharge of the shaft furnace gas and the zero-oxygen injection furnace gas, a shaft furnace gas outlet pipe 17 is arranged at the top of the gas-based shaft furnace 10, and a zero-oxygen injection furnace gas outlet pipe 29 is arranged at the top of the zero-oxygen injection furnace 20.
In the embodiment of the invention, the vertical direction inside the furnace body is divided into a solid material layer 21 and a soft melting drop zone 22 from top to bottom; the vertical direction inside the hearth is divided into a gas whirling region 23, a slag layer 24 and a molten iron layer 25 from top to bottom;
the hearth is positioned at the same horizontal section of the top of the gas swirling zone 23, a plurality of zero oxygen injection furnace reducing gas injection ports 210 are symmetrically distributed along the circumference, the hearth is positioned at the same horizontal section of the liquid slag layer 24, a plurality of slag holes 27 are symmetrically distributed along the circumference, the hearth is positioned at the same horizontal section of the liquid iron water layer 25, and a plurality of iron outlets 28 are symmetrically distributed along the circumference;
illustratively, in an embodiment of the invention the hearth has a rectangular longitudinal cross-section.
In the embodiment of the present invention, the diameter of the reducing gas injection port 210 of the zero oxygen injection furnace adopts an adjustable loop design to control the flow rate of the super-heated reducing gas injected by the reducing gas injection port 210 of the zero oxygen injection furnace;
the diameter of the hearth of the zero-oxygen injection furnace 20 and the flow rate of the injected super-heated reducing gas are controlled as follows:
when the diameter d of the hearth is less than 10m, the flow rate of the injected super-heated reducing gas is 150-350 m/s;
when the diameter d of the hearth is more than 10m, the flow rate of the injected super-heated reducing gas is 250-450 m/s.
The reaction process of the direct reduced iron in the zero oxygen injection furnace 20 (DRI deep reduction, melting and slag iron separation in the zero oxygen injection furnace 20) is as follows:
in the zero-oxygen injection furnace 20, DRI and solid carbon materials are added from the top charging equipment of the zero-oxygen injection furnace 20 and distributed on the surface of the solid material layer 21; the reducing gas (i.e. super-heated reducing gas) with super-high temperature (1800-2350 ℃) is supplied from the reducing gas blowing port 210 of the zero oxygen blowing furnace at high flow rate (flow rate 900-1500 Nm) 3 Ton of ferrite) is sprayed into the gas swirling zone 23 of the hearth, i.e., the super-heated reducing gas sprayed from the reducing gas spraying port 210 of the zero-oxygen spraying furnace does not directly enter the liquid iron water layer 25 and the slag layer 24;
when the high-pressure and high-flow-rate super-heated reducing gas is blown into the hearth at the front end of the reducing gas blowing opening 210 of the zero-oxygen blowing furnace, the material at the front end of the reducing gas blowing opening 210 of the zero-oxygen blowing furnace is blown out to form a high-temperature space taking gas as a main material, namely a gas convolution region 23, wherein the gas convolution region 23 is positioned between a liquid slag layer 24 and a soft melting and dripping region 22, and the air flow generated by the gas convolution region 23 plays a role in stirring the material passing through the horizontal section of the gas convolution region 23, so that hearth materials and temperature are uniformly distributed, and the physicochemical reaction of the hearth is more fully carried out;
After passing through the gas whirl region 23, the super-heated reducing gas upwards enters the soft molten drop region 22, and in the soft molten drop region 22, the super-heated reducing gas and DRI and solid carbon materials undergo severe heat exchange, so that the DRI temperature rises and softens and melts into a liquid slag-iron mixture, the liquid slag-iron mixture begins to drop under the action of gravity, and enters a hearth liquid molten pool through the gas whirl region 23, slag and molten iron are automatically layered due to different densities in the molten pool, molten iron sinks at the bottom to form a liquid molten iron layer 25, and slag floats above molten iron to form a liquid slag layer 24.
Liquid slag and iron in the hearth are respectively discharged from the hearth through a slag outlet 27 and a tap hole 28, and for ores with small slag quantity, the slag outlet can be eliminated, and the slag is discharged through the tap hole 28;
the liquid slag iron in the hearth is discharged to make room for the hearth, so that slag iron in the soft melting and dripping zone 22 continuously drips into the hearth, the burden of the solid material layer 21 sequentially moves downwards and enters the soft melting and dripping zone 22, the burden charging component 26 of the zero-oxygen blowing furnace continuously charges new burden on the surface of the solid material layer 21, and the thickness of the solid material layer 21 is kept unchanged;
the super-heated reducing gas enters the solid material layer 21 after heat exchange between the DRI and the solid carbon material in the soft melting and dripping zone 22, preheats the DRI and the solid carbon material in the solid material layer 21, and performs reduction reaction FeO+CO=Fe+CO with the iron oxide which is not completely reduced in the DRI 2 And/or FeO+H 2 ＝Fe+H 2 O, outputting gas products from a zero-oxygen injection furnace gas delivery pipe 29 at the top of the zero-oxygen injection furnace 20;
the melting point of carbon in the solid carbon material is higher than 4000 ℃, and in the smelting process, the solid carbon material is continuously heated along with the furnace burden descending until the solid carbon material enters a soft molten drop zone 22, a gas whirl zone 23, a slag layer 24 and a molten iron layer 25, and remains solid, which is called a solid material column;
the solid material columns are mainly distributed at the center of the hearth on the horizontal section of the gas swirling zone 23 under the influence of the high-flow-rate reducing gas in the gas swirling zone 23, and gradually diffuse to other areas of the hearth after entering the slag iron liquid;
in the molten iron layer 25, part of carbon in the solid material column is dissolved in molten iron to generate molten iron carburization reaction;
in the slag layer 24 and the soft melting and dripping zone 22, partial carbon in the solid material column and the iron oxide which is not completely reduced undergo direct reduction reaction FeO+C=Fe+CO, and a gas product CO rises and is output through a zero-oxygen blowing furnace gas delivery pipe 29 at the top of the furnace;
the molten iron carburizes and directly reduces the solid material column which is continuously 'dissolved and damaged', and the burden moving downwards at the upper part continuously provides a new solid material column, so that the solid material column is permanently existing and continuously replaced;
the high pressure gas flow in the solid column and gas swirling zone 23 acts as a support for the solid layer 21 of the shaft;
The gas generated by the chemical reaction in the zero-oxygen injection furnace 20 and the gas injected into the furnace without the chemical reaction are collectively referred to as zero-oxygen injection furnace gas, and the zero-oxygen injection furnace gas is output at the furnace top through the zero-oxygen injection furnace gas outlet pipe 29.
In some embodiments of the present invention, in order to improve the cooperation of pre-reduction and deep reduction in the gas-based shaft furnace 10 and the zero-oxygen injection furnace 20 and the reduction efficiency of the overall ironmaking apparatus, the inner diameter of the horizontal cross section of the hearth of the zero-oxygen injection furnace 20 (the diameter of the hearth of the zero-oxygen injection furnace 20 for short, the same applies hereinafter) is an important parameter for determining the molten iron productivity of the system; in order to ensure that the productivity of the ore prereduction system is matched with the slag iron melting productivity, the ratio of the inner diameter of the horizontal section of the lower part of the reduction section 11 of the gas-based shaft furnace 10 to the diameter of the hearth of the zero-oxygen injection furnace 20 is 1.0-1.3; the height of the material layer in the reduction section 11 of the gas-based shaft furnace 10 is 5-8 meters; the ratio of the hearth height of the zero-oxygen injection furnace 20 to the hearth diameter of the zero-oxygen injection furnace 20 is 0.35 to 0.6, and the ratio of the hearth height of the zero-oxygen injection furnace 20 to the hearth diameter of the zero-oxygen injection furnace 20 is 0.8 to 1.3.
In some embodiments of the invention, in order to save energy consumption of the ironmaking device, the zero oxygen injection low carbon ironmaking device further comprises a gas and heat recovery system;
The gas and heat recovery system comprises a shaft furnace gas and heat recovery subsystem and a zero-oxygen injection furnace gas and heat recovery subsystem;
the shaft furnace gas and heat recovery subsystem and the zero oxygen injection furnace gas and heat recovery subsystem can be independently arranged or can be partially or completely shared;
coarse dust removal is carried out on the gas output from the top of the shaft furnace at the temperature of 700-900 ℃ through a gravity dust remover to remove large-particle dust, then the gas enters a heat exchange system, heat is transferred to a heated medium and then is output from the heat exchange system, the gas is fed into a gas purification system 70 in the next step, and fine-particle dust is further removed and CO is removed 2 Removing H 2 O, called purified gas, in which CO 2 And H 2 The sum of the O volume percentages is less than1.5 percent, the purified gas is conveyed into a reduction gas holder for recycling.
Coarse dedusting is carried out on the gas output from the top of the zero-oxygen blowing furnace 20 at the temperature of 500-700 ℃, large-particle dust is removed through a gravity dust remover, then the gas enters a heat exchange system, heat is transferred to a heated medium and then is output from the heat exchange system, the gas is fed into a gas purification system 70 in the next step, firstly, fine-particle dust is removed, and then CO is selectively removed according to the gas components 2 And H 2 O, or directly output, the zero oxygen injection furnace gas output by the gas purifying system 70 is called purified gas, and CO in the purified gas 2 And H 2 The sum of the O volume percentages is less than 1.5 percent, and the purified gas is conveyed into a reduction gas tank for recycling.
In the embodiment of the invention, the shaft furnace gas and heat recovery subsystem comprises a first gravity dust remover 18 and a reduction gas holder 30, wherein the first gravity dust remover 18 is communicated with the shaft furnace gas delivery pipe 17 so as to remove impurities such as dust and the like in the shaft furnace gas;
the reduction gas holder 30 is communicated with a first pressurizing machine 31, and the first pressurizing machine 31 is communicated with a first heating furnace 40 through a first heat exchanger 32;
the first gravity dust collector 18 is communicated with a port of the reducing gas holder 30 through the first heat exchanger 32, and the port is different from a connecting port of the reducing gas holder 30 and the first gravity dust collector 18;
after being led out from the shaft furnace gas outlet pipe 17, the shaft furnace gas (high temperature) passes through the first gravity dust remover 18, and then exchanges heat with the reducing gas pressurized by the reducing gas holder 30 through the first pressurizing machine 31 in the first heat exchanger 32, so as to obtain shaft furnace purified gas, and the shaft furnace purified gas returns to the reducing gas holder 30;
in order to further remove dust, carbon dioxide and water vapour from the shaft furnace gas, the first gravity dust separator 18 is passed through the first heat exchanger 32 and a gas cleaning system 70 (acting as fine dust removal, CO removal 2 Removing H 2 O) is communicated with a reduction gas holder 30, namely the shaft furnace gas is subjected to dust removal, heat exchange and purification (fine dust removal and CO removal) 2 Removing H 2 O) after treatment, obtaining the purified gas of the shaft furnace, and returning to the reductionThe gas tank 30, the gas purifying system 70 is a device well known to those skilled in the art, and the present invention will not be described herein;
meanwhile, the reducing gas in the reducing gas holder 30 is preheated by heat exchange of the shaft furnace gas (high temperature), serves as a source of the hot reducing gas, is heated by the first heating furnace 40 (communicated with the hot reducing gas injection port 16), and then enters the gas-based shaft furnace 10 from the hot reducing gas injection port 16;
the subsystem fully recycles the heat energy and chemical energy of the shaft furnace gas on one hand, and purifies the shaft furnace gas on the other hand, recycles the shaft furnace gas as reducing gas, and realizes the double recycling of gas and heat;
the zero-oxygen injection furnace gas and heat recovery subsystem comprises a second gravity dust remover 211 and a reduction gas holder 30, wherein the second gravity dust remover 211 is communicated with the zero-oxygen injection furnace gas delivery pipe 29 so as to remove impurities such as dust in the zero-oxygen injection furnace gas;
The reducing gas holder 30 is communicated with a second pressurizing machine 50 (a connecting port is different from a connecting port of the reducing gas holder 30 and the first pressurizing machine 31), and the second pressurizing machine 50 is communicated with a second heating furnace 60 through a second heat exchanger 51;
the second gravity dust collector 211 is communicated with the reducing gas holder 30 through the second heat exchanger 51;
zero oxygen injection furnace gas (high temperature) is led out from the zero oxygen injection furnace gas leading-out pipe 29, passes through the second gravity dust remover 211, exchanges heat with the reducing gas pressurized by the reducing gas cabinet 30 through the second pressurizing machine 50 in the second heat exchanger 51 to obtain zero oxygen injection furnace purified gas, and returns to the reducing gas cabinet 30;
in order to further remove the dust in the zero-oxygen injection furnace gas, the second gravity dust remover 211 is communicated with the reduction gas tank 30 through the second heat exchanger 51 and the gas purification system 70 (the main function is fine dust removal), that is, the zero-oxygen injection furnace gas is subjected to dust removal, heat exchange and purification (fine dust removal) to obtain the zero-oxygen injection furnace purified gas, and the zero-oxygen injection furnace purified gas is returned to the reduction gas tank 30, wherein the reduction gas tank 30 is equipment well known to those skilled in the art, and the invention is not repeated herein;
At the same time, the reducing gas in the reducing gas holder 30 is preheated by the heat exchange of the zero-oxygen-injection furnace gas (high temperature), and is used as a source of the hot reducing gas, and then heated by the second heating furnace 60 (which is in communication with the zero-oxygen-injection furnace reducing gas injection port 210), and then enters the zero-oxygen-injection furnace 20 from the zero-oxygen-injection furnace reducing gas injection port 210.
In order to illustrate the implementation effect of the zero oxygen injection low-carbon ironmaking method and device provided by the embodiment of the invention, three grades of domestic typical iron ores in table 1 are taken and implemented in different atmospheres, and the components in table 1 are all in mass ratio, unit: percent of the total weight of the composition.
TABLE 1
Example 1
A zero oxygen injection low-carbon iron-making method is used for smelting domestic high-grade iron ore:
1.1 ore blending is carried out according to iron ore, flux and bentonite components, and various material components are shown in a table 2 (mass ratio, unit: percent).
TABLE 2
According to the proportion of 1.5 percent of bentonite, caO and SiO in pellets 2 The mass ratio=1.2 is subjected to balanced ore proportioning, and the mass ratio of each material is calculated as follows:
a, iron ore: flux: bentonite=96.4%: 2.1%:1.5%.
The ingredients of the self-fluxing oxidized pellets produced according to the proportion are shown in a table 3 (mass ratio, unit: percent).
TABLE 3 Table 3
| Variety of species | TFe | Fe 2 O 3 | FeO | SiO 2 | TiO 2 | Al 2 O 3 | CaO | MgO | Others | Totalizing |
| Pellet ore | 67.48 | 85.91 | 9.45 | 1.68 | 0.02 | 0.60 | 2.02 | 0.14 | 0.19 | 100 |
1.2 production of a gas-based shaft furnace 10 and a zero oxygen injection furnace 20 depending on the composition of the economic reduction gas
In a certain area H 2 The resources are rich, or H is obtained 2 Is lower than the cost of CO. At this time, the reducing gas component is H 2 If the gas-based shaft furnace 10 is mainly produced at lower cost, H can be selected 2 : organized production in a higher CO fashion, H 2 : co=5 (volume ratio, the same applies below) as an example.
The reducing gas composition is shown in Table 4 (volume ratio, unit:%).
TABLE 4 Table 4
| H 2 | CO | N 2 | Totalizing |
| 79.2 | 15.8 | 5.0 | 100 |
Pellet charge temperature=1000 ℃, total reducing gas flow rate=2000 Nm in the gas-based shaft furnace 10 3 Per ton of ferrite, K (cold reducing gas flow: hot reducing gas flow) =1.62, cold reducing gas flow=1237 Nm 3 Per ton of ferrite, cold reducing gas temperature=25 ℃, hot reducing gas flow=763 Nm 3 Per ton of ferrite, hot reducing gas temperature=1000℃. Total flow of reducing gas of gas-based shaft furnace 10=1832 Nm according to ore grade conversion 3 Per ton of DRI, wherein the cold reducing gas streamQuantity=1133 Nm 3 Per ton DRI, thermal reduction gas flow = 699Nm 3 Per ton of DRI.
Output flow from reduction gas cabinet=699nm 3 The reducing gas per ton of DRI is blown into the gas first heat exchanger 32 through the first compressor 31, the reducing gas is preheated to 300 ℃, the reducing gas is continuously blown into the first heating furnace 40 and heated to 1000 ℃, the reducing gas is changed into hot reducing gas, and the hot reducing gas is injected from the hot reducing gas injection port 16.
The DRI temperature = 250 ℃ discharged from the bottom of the gas-based shaft furnace 10 and the composition is shown in table 5 (mass ratio, unit%).
TABLE 5
| TFe | MFe | FeO | SiO2 | TiO2 | Al2O3 | CaO | MgO | Others | Totalizing |
| 91.6 | 84.3 | 9.4 | 2.3 | 0.0 | 0.8 | 2.7 | 0.2 | 0.3 | 100 |
Cold reducing gas is sprayed into the cooling section 12 from the cold reducing gas spraying inlet 14 of the gas-based shaft furnace 10, the temperature=514 ℃ when reaching the reduction section 11, and after being mixed with hot reducing gas sprayed from the hot reducing gas spraying inlet 16, the formed mixed reducing gas has the temperature=700 ℃, the mixed reducing gas reacts with iron oxides in pellets in the reduction section 11 to generate metallic iron and shaft furnace gas, and the composition of the shaft furnace gas is shown in table 6 (volume ratio, unit: percent). Shaft furnace gas is discharged from the shaft furnace gas discharge pipe 17, and shaft furnace gas flow = 1832Nm 3 After the shaft furnace gas passes through the first heat exchanger 32, the temperature is reduced, and further refined dust removal and CO removal are performed 2 And H 2 O, which becomes clean gas of the shaft furnace, the amount of CO2 removed is 189 kg/ton of ferrite, the composition of the clean gas of the shaft furnace is shown in Table 7 (volume ratio, unit:%) and the clean gas of the shaft furnace is=1332Nm 3 /tDRI＝1454m 3 Per ton of ferrite.
TABLE 6
| H 2 | CO | H 2 O | CO 2 | N 2 |
| 56.7％ | 11.0％ | 22.5％ | 4.8％ | 5.0％ |
TABLE 7
| H 2 | CO | N 2 |
| 78.0％ | 15.2％ | 6.9％ |
The solid carbon material used coke with a fixed carbon mass content of 85%. Coke and shaft furnace produced direct reduced iron DRI in mass ratio=0.064: 1 from the top charging assembly 26 of the zero oxygen injection furnace 20. The flow rate was set at 1000Nm by the second pressurizing machine 50 3 The ton of ferrite reducing gas is blown into the second heat exchanger 51, preheated to 300 ℃ in the second heat exchanger 51, then enters the second heating furnace 60, is further heated to 2250 ℃ to become super-heated reducing gas, and the super-heated reducing gas is blown in from the zero oxygen injection furnace reducing gas injection port 210 of the zero oxygen injection furnace 20.
In the zero oxygen injection furnace 20, the super-heated reducing gas and the solid direct reduced iron in the furnace undergo severe heat exchange to generate 1400-The temperature of the super-heated reducing gas is reduced from 2250deg.C to 1800-2000 deg.C by liquid mixed iron slag at 1600 deg.C, the super-heated reducing gas continuously preheats the direct reduced iron of the furnace body in the upward movement process, and finally the temperature is reduced to about 600deg.C, and the direct reduced iron is output from the furnace top zero-oxygen injection furnace gas outlet pipe 29. The high-temperature liquid mixed slag iron and the hot reducing gas and the solid coke are subjected to chemical reaction: feO+H 2 ＝H 2 O+Fe、H 2 O+C＝H 2 +CO、FeO+CO＝CO 2 +Fe、CO 2 +c=2co, feo+c=co+fe. The gas product in the furnace is output from a zero-oxygen injection furnace gas outlet pipe 29 at the furnace top, and the output gas is zero-oxygen injection furnace gas, and the zero-oxygen injection furnace gas amount=1032 Nm 3 The composition of the zero oxygen injection furnace gas per ton of molten iron is shown in Table 8 (volume ratio, unit:%).
TABLE 8
| H 2 | CO | N 2 | Totalizing |
| 76.71 | 18.44 | 4.84 | 100 |
Since the gas does not contain H 2 O and CO 2 Therefore, the purified gas of the zero-oxygen injection furnace can be obtained only by dedusting the gas.
1.3 effects of implementation
The cost of 2093 yuan/ton of molten iron in the production process is calculated by the market price of 1-8 months in 2023, and is shown in Table 9, compared with 2810 yuan/ton of molten iron in the traditional blast furnace, the cost is reduced by 717 yuan/ton, and the cost is reduced by 25.5%.
TABLE 9
The production process CO 2 The emission of the material is 189kg CO 2 Per ton of molten iron, compared with the prior gas-based shaft furnace 10 process CO 2 Physical emissions 287kgCO 2 Per ton of molten iron, 34% lower; converting energy and material consumption of production process into CO according to respective carbon emission factors 2 Discharging to obtain generalized CO in the production process 2 The discharge amount was 771.4kg CO 2 Per ton of molten iron, see Table 10, CO 2 1650kg CO discharged from the process for smelting high-grade ore by using the traditional blast furnace process 2 Per ton of molten iron, 878.6kg CO 2 Per ton of molten iron, is reduced by 53.2%.
Table 10
| Project name | Unit (B) | Carbon emission factor | Unit consumption | Carbon emission, kgCO 2 |
| Pellet production | kgce | 2.69 | 34.1 | 91.7 |
| Coke production | kgce | 2.69 | 7.5 | 20.2 |
| Heating of reducing gas | kgce | 2.69 | 122.6 | 329.7 |
| Coke | kg | 3.26 | 69.6 | 226.6 |
| Electric power | kwh | 0.57 | 240.0 | 136.9 |
| Reducing gas | m 3 | 0.31 | 3,000.0 | 933.0 |
| Purified gas of shaft furnace | m 3 | 0.30 | -1,453.8 | -432.8 |
| Zero oxygen blowing furnace purifying gas | m 3 | 0.36 | -1,032.0 | -373.9 |
| Molten iron | kg | 0.16 | -1,000.0 | -160.0 |
| Totalizing | 771.4 |
Example 2:
zero oxygen injection low-carbon iron-making method for smelting domestic medium-grade iron ore
2.1 ore blending is carried out according to iron ore, flux and bentonite components, wherein the components of various materials are shown in a table 11, and the components in the table 11 are in mass ratio, unit: percent of the total weight of the composition.
TABLE 11
According to the proportion of 1.5 percent of bentonite, caO and SiO in pellets 2 Balance ore proportioning is carried out according to mass ratio=1.2, and the mass ratio of each material is calculatedThe method comprises the following steps:
a, iron ore: flux: bentonite=91.2%: 7.3%:1.5%.
The ingredients of the self-fluxing oxidized pellets produced according to the proportion are shown in Table 12 (mass ratio, unit: percent).
Table 12
| TFe | Fe 2 O 3 | FeO | SiO 2 | TiO 2 | Al 2 O 3 | CaO | MgO | Others | Totalizing |
| 56.56 | 80.43 | 0.33 | 6.20 | 0.15 | 4.18 | 7.44 | 0.99 | 0.27 | 100 |
2.2 production of a gas-based shaft furnace 10 organized according to economic reduction gas composition
In a certain area, the reducing gas H is limited by resource and price factors 2 : CO is economical in a certain range, and is produced in a most economical way by H 2 : for example, co=1.0, and the reducing gas composition is shown in table 13 (volume ratio, unit:%).
TABLE 13
| H 2 | CO | N 2 | Totalizing |
| 47.5 | 47.5 | 5.0 | 100 |
Pellet charging temperature=980 ℃, total reducing gas flow rate of the gas-based shaft furnace 10=2100 Nm 3 Per ton of ferrite, K (cold reducing gas flow: hot reducing gas flow) =1.47, cold reducing gas flow=1249 Nm is selected 3 Ton of ferrite, cold reducing gas temperature=25 ℃, hot reducing gas flow=851 Nm 3 Per ton of ferrite, hot reducing gas temperature=980 ℃. According to ore gradeCalculated total flow of reducing gas in the gas-based shaft furnace 10=1541nm 3 Dri, wherein cold reducing gas flow = 917Nm 3 Dri, thermal reducing gas flow = 624Nm 3 /tDRI。
Output flow from reduction gas cabinet = 624Nm 3 The reducing gas of/tdi is blown into the gas first heat exchanger 32 through the first pressurizing machine 31, the reducing gas is preheated to 300 ℃, the reducing gas is continuously blown into the first heating furnace 40, and the reducing gas is heated to 980 ℃ to become hot reducing gas, and the hot reducing gas is injected from the hot reducing gas injection port 16.
The DRI temperature = 250 ℃ discharged from the bottom of the gas-based shaft furnace 10 and the composition is shown in table 14 (mass ratio, unit%).
TABLE 14
| TFe | MFe | FeO | SiO 2 | TiO 2 | Al 2 O 3 | CaO | MgO | Others | Totalizing |
| 73.4 | 67.5 | 7.5 | 8.0 | 0.2 | 5.4 | 9.7 | 1.3 | 0.4 | 100 |
Cold reducing gas is sprayed into the cooling section 12 from the cold reducing gas spraying inlet 14 of the gas-based shaft furnace 10, the temperature=521 ℃ when reaching the reduction section 11, and after being mixed with hot reducing gas sprayed from the hot reducing gas spraying inlet 16, the formed mixed reducing gas has the temperature=700 ℃, the mixed reducing gas reacts with iron oxides in pellets in the reduction section 11 to generate metallic iron and shaft furnace gas, and the composition of the shaft furnace gas is shown in table 15 (volume percent, unit: percent). Shaft furnace gas is discharged from the shaft furnace gas discharge pipe 17, and the shaft furnace gas flow rate=1541nm 3 After the shaft furnace gas passes through the first heat exchanger 32, the temperature is reduced, and further refined dust removal and CO removal are performed 2 And H 2 O becomes the clean gas of the shaft furnace, and the removed CO 2 The amount was 577 kg/ton ferrite and the composition of the clean gas of the shaft furnace is shown in Table 16 (volume percent, unit:%), clean gas of the shaft furnace=1125 Nm 3 /tDRI＝1533m 3 Per ton of ferrite.
TABLE 15
| H 2 | CO | H 2 O | CO 2 | N 2 |
| 34.5％ | 33.5％ | 13.0％ | 14.0％ | 5.0％ |
Table 16
| H 2 | CO | N 2 |
| 47.2％ | 45.9％ | 6.8％ |
The solid carbon material used coke with a fixed carbon mass content of 85%. Coke and shaft furnace produced direct reduced iron DRI in mass ratio = 0.051:1 from the top charging assembly 26 of the zero oxygen injection furnace 20. The flow rate was 1100Nm by the second pressurizing machine 50 3 The ton of ferrite reducing gas is blown into the second heat exchanger 51, preheated to 300 ℃ in the second heat exchanger 51, then enters the second heating furnace 60, and is further heated to 2200 ℃ to become super-heated reducing gas, and the super-heated reducing gas is blown from the zero oxygen blowing furnace reducing gas of the zero oxygen blowing furnace 20Port 210 is blown in.
In the zero oxygen injection furnace 20, the super-heated reducing gas and the solid direct reduced iron in the furnace undergo severe heat exchange to generate 1400-1600 ℃ liquid mixed slag iron, the temperature of the super-heated reducing gas is reduced from 2200 ℃ to 1800-2000 ℃, the super-heated reducing gas continuously preheats the direct reduced iron of the furnace body in the upward movement process, and finally the temperature is reduced to about 600 ℃ and is output from a zero oxygen injection furnace gas delivery pipe 29 at the furnace top. The high-temperature liquid mixed slag iron and the hot reducing gas and the solid coke are subjected to chemical reaction: feO+H 2 ＝H 2 O+Fe、H 2 O+C＝H 2 +CO、FeO+CO＝CO 2 +Fe、CO 2 +c=2co, feo+c=co+fe. The gas generated by the reaction is output from the zero-oxygen injection furnace gas delivery pipe 29 along with the super-heated reducing gas which does not participate in the chemical reaction, and the output gas is the zero-oxygen injection furnace gas, and the zero-oxygen injection furnace gas volume=1132Nm 3 The composition of the zero oxygen injection furnace gas per ton of molten iron is shown in Table 17 (volume percent, unit: percent).
TABLE 17
Since the gas does not contain H 2 O and CO 2 Therefore, the purified gas of the zero-oxygen injection furnace can be obtained only by dedusting the gas.
2.3 effects of implementation
The cost of 1998 yuan per ton of molten iron in the production process is calculated by the market price of 2023 in 1-8 months, and is shown in Table 18, the cost is lower than 2810 yuan per ton of the conventional blast furnace molten iron, 812 yuan per ton is lower, and the cost is reduced by 28.9%.
TABLE 18
The production process CO 2 The emission of the material is 577kg CO 2 Per ton of molten ironThe method comprises the steps of carrying out a first treatment on the surface of the Converting energy and material consumption of production process into CO according to respective carbon emission factors 2 Discharging to obtain generalized CO in the production process 2 The discharge amount was 1216.8kg CO 2 Per ton of molten iron, see Table 19, CO 2 The discharge amount of 1797kg CO of the medium-grade ore smelted by the traditional blast furnace is higher than that of 1797kg CO of medium-grade ore smelted by the traditional blast furnace 2 Per ton of molten iron, 580.2kg CO 2 Per ton of molten iron, CO 2 The discharge amount is reduced by 32.3 percent.
TABLE 19
Example 3:
low-grade refractory iron ore smelted by zero-oxygen blowing low-carbon ironmaking method
The domestic low-grade refractory ore is the iron ore resource with the highest carbon reduction difficulty and the most difficult task, and the smelting process is CO 2 The emission amount reaches 2150kg CO 2 Per ton of molten iron, prior to the present invention, no technical measure has been found that is cost effective for reducing carbon emissions.
3.1, ore blending is carried out according to iron ore, flux and bentonite components, the components in the table 20 are in mass ratio, and the components in the table 20 are in units: percent of the total weight of the composition.
Table 20
According to the proportion of 1.5 percent of bentonite, caO and SiO in pellets 2 The mass ratio=1.05 is subjected to balanced ore proportioning, and the mass ratio of each material is calculated as follows:
a, iron ore: flux: bentonite=93.0%: 5.5%:1.5%.
Ingredients according to the proportion are proportioned, and the ingredients obtained from the fusible oxidized pellets are shown in Table 21 (mass ratio, unit: percent).
Table 21
| TFe | Fe 2 O 3 | FeO | SiO 2 | TiO 2 | Al 2 O 3 | CaO | MgO | Others | Totalizing |
| 51.16 | 38.77 | 30.88 | 5.35 | 10.70 | 4.18 | 5.63 | 4.03 | 0.47 | 100 |
3.2 gas-based shaft furnace production organized according to economic reduction gas composition
3.2.1 Low H 2 : CO smelting and effect
(1) By H 2 : production of co=0.2 tissue gas-based shaft furnace 10 and zero oxygen injection furnace 20
In a certain area H 2 The resources are relatively poor, or H is obtained 2 Is higher than the cost of CO. At this time, H can be selected 2 : organized production in a low CO fashion, in H 2 : for co=0.2, the reducing gas composition is shown in table 22 (volume ratio, unit:%).
Table 22
| H 2 | CO | N 2 | Totalizing |
| 15.8 | 79.2 | 5.0 | 100 |
Pellet charging temperature=930 ℃, total reducing gas flow rate of the gas-based shaft furnace 10=2200 Nm 3 Per ton of ferrite, K (cold reducing gas flow: hot reducing gas flow) =1.26, cold reducing gas flow=1227nm 3 Per ton of ferrite, cold reducing gas temperature=25 ℃, hot reducing gas flow=973 Nm 3 Per ton of ferrite, hot reducing gas temperature=930℃. Total flow of reducing gas of gas-based shaft furnace 10=1361nm according to ore grade conversion 3 tDRI, wherein, cold reductionAir flow = 759Nm 3 Dri, thermal reducing gas flow = 602Nm 3 /tDRI。
Output flow from reduction gas cabinet = 602Nm 3 The reducing gas of/tdi is blown into the gas first heat exchanger 32 through the first compressor 31, the reducing gas is preheated to 300 ℃, the reducing gas is continuously blown into the first heating furnace 40 and heated to 930 ℃, the reducing gas is formed into hot reducing gas, and the hot reducing gas is injected from the hot reducing gas injection port 16.
The DRI temperature = 250 ℃ discharged from the bottom of the gas-based shaft furnace 10 and the composition is shown in table 23 (mass ratio, unit%).
Table 23
| TFe | MFe | FeO | SiO 2 | TiO 2 | Al 2 O 3 | CaO | MgO | Others | Totalizing |
| 61.9 | 56.9 | 6.4 | 6.5 | 12.9 | 5.1 | 6.8 | 4.9 | 0.6 | 100 |
Cold reducing gas is sprayed into the cooling section 12 from the cold reducing gas spraying inlet 14 of the gas-based shaft furnace 10, the temperature=518 ℃ when reaching the reduction section 11, and after being mixed with hot reducing gas sprayed from the hot reducing gas spraying inlet 16, the formed mixed reducing gas has the temperature=700 ℃, the mixed reducing gas reacts with iron oxides in pellets in the reduction section 11 to generate metallic iron and shaft furnace gas, and the composition of the shaft furnace gas is shown in table 24 (volume ratio, unit: percent). Shaft furnace gas is discharged from the shaft furnace gas discharge pipe 17, and the shaft furnace gas flow = 1361Nm 3 After the shaft furnace gas passes through the first heat exchanger 32, the temperature is reduced, and further refined dust removal and CO removal are performed 2 And H 2 O becomes the clean gas of the shaft furnace, the removed CO2 amount is 787 kg/ton of ferrite, the composition of the clean gas of the shaft furnace is shown in Table 25 (volume percent, unit:%) and the clean gas amount of the shaft furnace is=1068Nm 3 /tDRI＝1726m 3 Per ton of ferrite.
Table 24
| H 2 | CO | H 2 O | CO 2 | N 2 |
| 12.5％ | 60.9％ | 3.3％ | 18.2％ | 5.0％ |
Table 25
| H 2 | CO | N 2 |
| 15.9％ | 77.7％ | 6.4％ |
The solid carbon material used coke with a fixed carbon mass content of 85%. Coke and shaft furnace produced direct reduced iron DRI in mass ratio = 0.043:1 from the top charging assembly 26 of the zero oxygen injection furnace 20. The flow rate was 1200Nm by the second pressurizing machine 50 3 The ton of ferrite reducing gas is blown into the second heat exchanger 51, preheated to 300 ℃ in the second heat exchanger 51, then enters the second heating furnace 60, is further heated to 2150 ℃ to become super-heated reducing gas, and the super-heated reducing gas is blown in from the zero-oxygen blowing furnace reducing gas blowing port 210.
In the zero oxygen injection furnace 20, the super-heated reducing gas and the solid-state direct reduction in the furnaceThe iron undergoes intense heat exchange to generate 1400-1600 ℃ liquid mixed slag iron, the temperature of the super-heated reducing gas is reduced from 2150 ℃ to 1800-2000 ℃, the super-heated reducing gas continuously preheats the direct reduced iron of the furnace body in the upward movement process, and finally the temperature is reduced to about 600 ℃ and is output from the furnace top zero-oxygen injection furnace gas delivery pipe 29. The high-temperature liquid mixed slag iron and the hot reducing gas and the solid coke are subjected to chemical reaction: feO+H 2 ＝H 2 O+Fe、H 2 O+C＝H 2 +CO、FeO+CO＝CO 2 +Fe、CO 2 +c=2co, feo+c=co+fe. The gas generated by the reaction is output from the zero-oxygen injection furnace gas delivery pipe 29 along with the super-heated reducing gas which does not participate in the chemical reaction, and the output gas is the zero-oxygen injection furnace gas, and the zero-oxygen injection furnace gas volume=1232 Nm 3 The composition of the molten iron/t and the zero oxygen injection furnace gas is shown in Table 26 (volume percent, unit: percent).
Table 26
| H 2 | CO | N 2 | Totalizing |
| 15.42 | 79.71 | 4.87 | 100 |
Since the gas does not contain H 2 O and CO 2 Therefore, the purified gas of the zero-oxygen injection furnace can be obtained only by dedusting the gas.
(2) Effect of the invention
The production process cost is 1288 yuan/ton of molten iron measured and calculated according to the market price of 1-8 months in 2023, the detail is shown in table 27, the cost is lower than 2810 yuan/ton of the conventional blast furnace molten iron, the cost is 1522 yuan/ton, and the cost is reduced by 54.2%.
Table 27
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The production process CO 2 The emission of the material is 787kg CO 2 Per ton of molten iron; converting energy and material consumption of production process into CO according to respective carbon emission factors 2 Discharging to obtain generalized CO in the production process 2 The discharge amount was 1477.7kg CO 2 Per ton of molten iron, see Table 28 for details, CO 2 2150kg CO of low-grade ore smelted by traditional blast furnace 2 Per ton of molten iron, 672.3kg CO 2 Per ton of molten iron, CO 2 The discharge amount is reduced by 31.3 percent.
Table 28
3.2.2 high H 2 : CO smelting and effect
(1) The reducing gas is produced by using the reducing gas as an active ingredient and adopting a full hydrogen gas structure gas-based shaft furnace 10 and a zero oxygen injection furnace 20, wherein the reducing gas ingredient is shown in a table 29 (volume ratio, unit: percent).
Table 29
| H 2 | CO | N 2 | Totalizing |
| 95 | 0 | 5.0 | 100 |
Pellet charging temperature=1050 ℃, total reducing gas flow rate of the gas-based shaft furnace 10=1800 Nm 3 Per ton of ferrite, K (cold reducing gas flow: hot reducing gas flow) =2.02, cold reducing gas flow=1204 Nm 3 T ferrite, cold reducing gas temperature=25 ℃, hot reducing gas flow=596 Nm 3 Per ton of ferrite, hot reducing gas temperature=1050℃. Total flow of reducing gas of gas-based shaft furnace 10 according to ore grade conversion=1114 Nm 3 Dri, wherein cold reducing gas flow = 745Nm 3 Dri, thermal reducing gas flow = 369Nm 3 /tDRI。
Output flow from reduction gas cabinet = 369Nm 3 The reducing gas of/tdi is blown into the first heat exchanger 32 (gas heat exchanger) by the first compressor 31, the reducing gas is preheated to 300 ℃, the reducing gas is continuously blown into the first heating furnace 40 and heated to 1050 ℃, the reducing gas is formed into hot reducing gas, and the hot reducing gas is injected from the hot reducing gas injection port 16.
The DRI temperature = 250 ℃ discharged from the bottom of the gas-based shaft furnace 10 and the composition is shown in table 30 (mass ratio, unit%).
Table 30
| TFe | MFe | FeO | SiO 2 | TiO 2 | Al 2 O 3 | CaO | MgO | Others | Totalizing |
| 61.9 | 56.9 | 6.4 | 6.5 | 12.9 | 5.1 | 6.8 | 4.9 | 0.6 | 100 |
Cold reducing gas is sprayed into the cooling section 12 from the cold reducing gas spraying inlet 14 of the gas-based shaft furnace 10, the temperature=527 ℃ when reaching the reduction section 11, and after being mixed with hot reducing gas sprayed from the hot reducing gas spraying inlet 16, the formed mixed reducing gas has the temperature=700 ℃, the mixed reducing gas reacts with iron oxides in pellets in the reduction section 11 to generate metallic iron and shaft furnace gas, and the composition of the shaft furnace gas is shown in table 31 (volume ratio, unit: percent). Shaft furnace gas is discharged from the shaft furnace gas discharge pipe 17, and the shaft furnace gas flow = 1114Nm 3 tDRI, shaft furnaceThe temperature of the gas=750 ℃, the temperature of the shaft furnace gas is reduced after the shaft furnace gas passes through the first heat exchanger 32, and then the gas is further refined to remove dust and CO 2 And H 2 O becomes the clean gas of the shaft furnace, and the removed CO 2 The amount is 0 kg/ton ferrite, the composition of the clean gas of the shaft furnace is shown in Table 32 (volume ratio, unit:%), the clean gas amount of the shaft furnace=821 Nm 3 /tDRI＝1326m 3 Per ton of ferrite.
Table 31
| H 2 | CO | H 2 O | CO 2 | N 2 |
| 68.7％ | 0.0％ | 26.3％ | 0.0％ | 5.0％ |
Table 32
| H 2 | CO | N 2 |
| 93.2％ | 0.0％ | 6.8％ |
The solid carbon material used coke with a fixed carbon mass content of 85%. Coke and shaft furnace produced direct reduced iron DRI in mass ratio = 0.043:1 from the top charging assembly 26 of the zero oxygen injection furnace 20. The reducing gas with the flow rate of 1200Nm3/tHM is blown into the second heat exchanger 51 through the second pressurizing machine 50, preheated to 300 ℃ in the second heat exchanger 51, then enters the second heating furnace 60, is further heated to 2150 ℃ to become super-heated reducing gas, and the super-heated reducing gas is blown in from the zero oxygen blowing furnace reducing gas blowing port 210.
In the zero oxygen injection furnace 20, the super-heated reducing gas and the solid direct reduced iron in the furnace undergo severe heat exchange to generate 1400-1600 ℃ liquid mixed slag iron, the temperature of the super-heated reducing gas is reduced from 2150 ℃ to 1800-2000 ℃, the super-heated reducing gas continuously preheats the direct reduced iron of the furnace body in the upward movement process, and finally the temperature is reduced to about 600 ℃ and is output from the zero oxygen injection furnace gas delivery pipe 29. The high-temperature liquid mixed slag iron and the hot reducing gas and the solid coke are subjected to chemical reaction: feO+H 2 ＝H 2 O+Fe、H 2 O+C＝H 2 +CO、FeO+CO＝CO2+Fe、CO 2 +c=2co, feo+c=co+fe. The gas generated by the reaction is output from the zero-oxygen injection furnace gas delivery pipe 29 along with the super-heated reducing gas which does not participate in the chemical reaction, and the output gas is the zero-oxygen injection furnace gas, and the zero-oxygen injection furnace gas volume=1232 Nm 3 The composition of the molten iron/t and the zero oxygen injection furnace gas is shown in Table 33 (volume ratio, unit: percent).
Table 33
| H 2 | CO | N 2 | Totalizing |
| 92.53 | 2.60 | 4.87 | 100 |
Since the gas does not contain H 2 O and CO 2 Therefore, the purified gas of the zero-oxygen injection furnace can be obtained only by dedusting the gas.
(2) Effect of the invention
The recovery rate of iron element in the production process is 98.4 percent, which is 2.6 percent higher than that in 95.8 percent of the blast furnace process and 29.7 percent higher than that in 68.7 percent of the gas-based shaft furnace-electric furnace melting process; the recovery rate of V element is 71.2%, which is 1.9% higher than 69.3 of the blast furnace process and 21.5% higher than 47.8% of the gas-based shaft furnace-electric furnace melting process.
The market price of 2023 is 1-8 months, the production process cost is 1260 yuan/ton of molten iron, the detail is shown in table 34, and compared with the conventional blast furnace molten iron cost 2810 yuan/ton, the cost is 1550 yuan/ton, and the cost is reduced by 55.2%.
Watch 34
The production process CO 2 The emission of the material object is 0kg CO 2 Per ton of molten iron; converting energy and material consumption of production process into CO according to respective carbon emission factors 2 Discharging to obtain generalized CO in the production process 2 The emission amount is the CO in the production process 2 The discharge amount was 622.34kg CO 2 Per ton of molten iron, see Table 35, CO 2 2150kg CO of low-grade ore smelted by traditional blast furnace 2 Per ton of molten iron, 1527.7kg CO 2 Per ton of molten iron, CO 2 The discharge amount was reduced by 71.1%.
Table 35
Although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (10)
1. The zero oxygen injection low-carbon ironmaking method is characterized by comprising the following steps of:
filling hot self-fluxing oxidized pellets into a gas-based shaft furnace (10) from the top of the furnace, spraying cold reducing gas into the gas-based shaft furnace (10) from the bottom of the gas-based shaft furnace (10), and simultaneously spraying hot reducing gas into the gas-based shaft furnace (10) from the junction of a reduction section (11) and a cooling section (12) of the gas-based shaft furnace (10), wherein the cold reducing gas is heated in the rising process and mixed with the hot reducing gas, and then is subjected to pre-reduction reaction with the self-fluxing oxidized pellets to obtain hot direct reduced iron, and the hot direct reduced iron is cooled by the cold reducing gas in the cooling section (12) to obtain direct reduced iron;
The solid carbon material and the direct reduced iron are mixed according to the mass ratio of (0.03-0.1): 1, charging from the top of a zero oxygen injection furnace (20), charging the furnace at 1800-2350 ℃ and with a flow rate of 900-1500 Nm 3 And injecting the super-heated reducing gas of per ton of ferrite into a zero-oxygen injection furnace (20), and reducing and melting the direct reduced iron to obtain liquid slag and molten iron.
2. A according to claim 1The zero-oxygen blowing low-carbon ironmaking method is characterized in that the temperature of the hot self-fluxing oxidized pellets is 600-1100 ℃, and CaO and SiO in the self-fluxing oxidized pellets 2 The mass ratio is 0.9-1.3, and the mass ratio of Fe element in the self-fluxing oxidized pellet ore is 50-69%; the temperature of the cold reducing gas is less than 50 ℃; the temperature of the obtained direct reduced iron after the hot direct reduced iron is cooled by the cold reducing gas in the cooling section (12) is less than 250 ℃, and the metallization rate is more than or equal to 92%; the fixed carbon content in the solid carbon material is more than 75%.
3. The zero-oxygen injection low-carbon ironmaking method according to claim 1, wherein the hot reducing gas and the super-hot reducing gas are reducing gas cabinet reducing gas, and the cold reducing gas is reducing gas cabinet reducing gas and/or coke oven gas;
the reducing gas of the reducing gas cabinet comprises purified gas and new supplementary reducing gas, and the reducing gas of the reducing gas cabinet comprises CO and H as the gas components 2 、N 2 And impurity gases, and CO and H 2 The sum of the volume percentages is more than 92%;
the purified gas is gas obtained by recovering heat energy and purifying the top gas of the gas-based shaft furnace (10) and the zero-oxygen injection furnace (20) through heat exchange.
4. The zero oxygen injection low carbon ironmaking method according to claim 1, characterized in that the total flow of gas in the gas-based shaft furnace (10) comprises a cold reducing gas flow and a hot reducing gas flow, wherein the ratio of the cold reducing gas flow and the hot reducing gas flow is K;
when injecting reducing gas H into a gas-based shaft furnace (10) 2 When CO is more than 5, the self-fluxing oxidized pellet ore charging temperature isThe total flow of the reducing gas in the gas-based shaft furnace (10) is +.>Ferrite, K is in the range +.>The temperature of the hot reducing gas is 1050+/-20 ℃;
when the reducing gas is injected into the gas-based shaft furnace (10) and is less than 1.5 < H 2 When CO is less than or equal to 5, the charging temperature of the self-fluxing oxidized pellet ore isThe total flow of the reducing gas in the gas-based shaft furnace (10) is +.> Ferrite, K is in the range +.>The temperature of the hot reducing gas is->
When the reducing gas is injected into the gas-based shaft furnace (10) and is less than 0.6 and less than H 2 When CO is less than or equal to 1.5, the charging temperature of the self-fluxing oxidized pellet ore isThe total flow of the reducing gas in the gas-based shaft furnace (10) is +.> Ferrite, K is in the range +.>The temperature of the hot reducing gas is 980+/-20 ℃;
When the reducing gas 0.2 </in the gas-based shaft furnace (10) is injectedH 2 When CO is less than or equal to 0.6, the charging temperature of the self-fluxing oxidized pellet ore isThe total flow of the reducing gas in the gas-based shaft furnace (10) is +.> Ferrite, K is in the range ofThe temperature of the hot reducing gas is 950+/-20 ℃;
when injecting reducing gas H into a gas-based shaft furnace (10) 2 When CO is less than or equal to 0.2, the charging temperature of the self-fluxing oxidized pellet ore isThe total flow of the reducing gas in the gas-based shaft furnace (10) is +.>Ferrite, K is in the range ofThe temperature of the hot reducing gas is 930+/-20 ℃.
5. A zero oxygen injection low carbon ironmaking method according to any one of claims 1-3, characterized in that the furnace inflow and furnace inflow temperature control range of the super hot reducing gas injected into the zero oxygen injection furnace (20) is specifically as follows:
when the flow rate of the super-heated reducing gas blown into the furnace is 900-1200 Nm 3 When per ton of ferrite, the temperature of the super-heated reducing gas entering the furnace is controlled to 2130-2320 ℃;
when the flow rate of the super-heated reducing gas blown into the furnace is 1200-1500 Nm 3 When per ton of ferrite, the temperature of the super-heated reducing gas entering the furnace is controlled to 1850 to the upper range2250℃。
6. A zero-oxygen injection low-carbon ironmaking device, characterized in that a zero-oxygen injection low-carbon ironmaking method according to any one of claims 1-4 is realized, comprising a gas-based shaft furnace (10) and a zero-oxygen injection furnace (20);
the gas-based shaft furnace (10) is divided into a reduction section (11) and a cooling section (12) from top to bottom along the vertical direction inside;
A plurality of hot reducing gas injection ports (16) are symmetrically arranged on the same horizontal section at the junction of the reducing section (11) and the cooling section (12), and the reducing section (11) is used for the pre-reduction reaction of the self-fluxing oxidized pellets to obtain hot direct reduced iron;
a plurality of cold reducing gas injection ports (14) are symmetrically arranged on the same horizontal section in the lower part of the cooling section (12), and the cooling section (12) is used for cooling hot direct reduced iron to obtain cold direct reduced iron;
the direct reduced iron discharged from the bottom of the cooling section (12) is transported to the zero-oxygen injection furnace (20), the zero-oxygen injection furnace (20) is a non-electric furnace and a non-blast furnace, the oxygen blowing amount is zero, the inside of the zero-oxygen injection furnace (20) is divided into a furnace body and a furnace hearth from top to bottom along the vertical central line of the zero-oxygen injection furnace, and the zero-oxygen injection furnace (20) is used for reducing and melting the direct reduced iron to obtain liquid slag and molten iron.
7. The zero oxygen blowing low-carbon ironmaking device according to claim 6, characterized in that the vertical direction inside the furnace body is divided into a solid material layer (21) and a soft melting drop zone (22) from top to bottom; the vertical direction inside the hearth is divided into a gas whirling region (23), a slag layer (24) and a molten iron layer (25) from top to bottom.
8. The zero oxygen injection low carbon ironmaking apparatus of claim 7, characterized in that the hearth is located at the same horizontal section of the gas swirling zone (23), a plurality of reducing gas injection ports (210) are symmetrically distributed along the circumference, the hearth is located at the same horizontal section of the liquid slag layer (24), a plurality of slag holes (27) are symmetrically distributed along the circumference, the hearth is located at the same horizontal section of the liquid iron water layer (25), and a plurality of tapping holes (28) are symmetrically distributed along the circumference.
9. The zero oxygen injection low carbon ironmaking apparatus of claim 8, characterized in that the diameter of the zero oxygen injection furnace reducing gas injection port (210) is adjustable loop design, and the diameter of the furnace hearth of the zero oxygen injection furnace (20) and the flow rate of the injected super-heated reducing gas are controlled as follows:
when the diameter d of the hearth is less than 10m, the flow rate of the injected super-heated reducing gas is 150-350 m/s;
when the diameter d of the hearth is more than 10m, the flow rate of the injected super-heated reducing gas is 250-450 m/s.
10. The zero oxygen injection low carbon ironmaking installation according to any one of claims 7 to 9, characterized in that the ratio of the inner diameter of the lower horizontal cross section of the reduction section (11) of the gas-based shaft furnace (10) to the hearth diameter of the zero oxygen injection furnace (20) is 1.0 to 1.3; the height of the material layer in the reduction section (11) of the gas-based shaft furnace (10) is 5-8 meters; the ratio of the hearth height of the zero-oxygen injection furnace (20) to the hearth diameter of the zero-oxygen injection furnace (20) is 0.35-0.6, and the ratio of the hearth height of the zero-oxygen injection furnace (20) to the hearth diameter of the zero-oxygen injection furnace (20) is 0.8-1.3.
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