CN115874008A - Method for recycling converter gas in large scrap ratio mode - Google Patents
Method for recycling converter gas in large scrap ratio mode Download PDFInfo
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- CN115874008A CN115874008A CN202211536481.9A CN202211536481A CN115874008A CN 115874008 A CN115874008 A CN 115874008A CN 202211536481 A CN202211536481 A CN 202211536481A CN 115874008 A CN115874008 A CN 115874008A
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Abstract
The invention provides a method for recovering converter gas in a large scrap ratio mode, which comprises the following steps: filling a metal material: adding scrap steel and molten iron into a converter in sequence according to a certain proportion; converter smelting and coal gas recovery: and (3) after the converter smelting is started, adopting a cross blowing mode to blow the gas powder mixture at the bottom, and if the converter recovery condition is met, beginning to recover converter gas until the converter smelting is finished. The invention has the advantages that through various processes of cross bottom blowing gas, powdery slag charge, top blowing at the top of the furnace and the like, different types of waste steel are added in batches in point positions, the whole process of converter smelting meets the coal gas recovery requirement under the mode of large waste steel ratio, the whole process of converter coal gas recovery is realized, and the recovery amount can be 200m 3 More than t, the average CO content can reach more than 48 percent, and conditions are created for improving the converter negative energy steelmaking level.
Description
Technical Field
The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a method for recovering converter gas in a large scrap ratio mode.
Background
The steel industry of China gradually develops towards low carbon, and energy recycling becomes a key work. Flue gas is generated in the smelting process of the converter, and the coal gas is recycled after the flue gas passes through the purification and recovery system. In order to avoid high-temperature flue gas explosion, the common coal gas recovery conditions are that the oxygen content is 1.5 percent, and the CO content of the coal gas reaches more than 15 percent and the coal gas is recovered. At the initial stage of coal gas recovery, silicon and manganese elements in molten iron are mainly oxidized, the carbon content in flue gas is low, oxygen content in the flue gas exceeds the standard due to insufficient oxygen combustion, and the molten iron cannot be recovered. Under the mode of large scrap ratio, the proportion of the scrap steel used by the converter is higher and higher, the heat in the converter is insufficient, the oxygen content of the smoke generated by insufficient combustion is high, the CO content cannot reach the recovery condition, the initial point of coal gas recovery is further delayed, and the recovery amount of the coal gas is low.
In order to realize the whole process recovery of converter gas, methods of using different devices to prepare carbon-containing raw materials such as coal blowing and the like are mostly adopted, such as the following patents: a converter smelting device and a converter smelting method (CN 114807500A) for recycling coal gas in the whole process provide an operation method for injecting coal powder at the early stage of smelting by adopting a coal-oxygen lance, the coal injection mode further improves the consumption of carbon, and the development trend of low-carbon metallurgy is not met.
The patent: a method for increasing the CO content of converter gas (CN 111575431A) adopts the addition of FeO-containing materials and slag-making process adjustment to increase the CO content in the gas. The method is suitable for smelting conditions with high heat conditions, is not suitable for a smelting mode with a large scrap steel ratio, and cannot realize the whole-process recovery of converter gas.
Disclosure of Invention
The invention aims to solve the problem of providing a method for recovering converter gas in a large scrap ratio mode, and when the scrap ratio is more than 35%, the converter gas is completely recovered by meeting the gas recovery requirement in the whole converter smelting process through various processes such as a bottom blowing gas and powdery slag charge mode.
In order to solve the technical problems, the invention adopts the technical scheme that: a method for recycling converter gas in a large scrap ratio mode comprises the following steps:
loading a metal material: adding scrap steel and molten iron into a converter in sequence according to a certain proportion;
converter smelting and coal gas recovery: and (3) adopting a cross blowing mode to blow a gas-powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished.
Further, in the steps of charging the metal material, smelting in a converter and recovering coal gas, the proportion of the total molten iron added into the foundry ladle is 60-65%, and the proportion of the total scrap steel is 35-40%.
Further, the metal material is charged: the method for adding the scrap steel and the molten iron into the converter in sequence according to a certain proportion comprises the following steps:
adding the crushed first batch of scrap steel into the ladle;
pouring molten iron into a ladle after adding the first batch of scrap steel;
and (4) charging the first batch of scrap steel and molten iron into the converter, and starting converter smelting.
Furthermore, the granularity of the broken scrap steel is 20-30mm, and the thickness of the broken scrap steel is 3-5mm; adding the crushed scrap steel into a ladle until the height of the crushed scrap steel is not more than 1/2 of the height of the ladle;
after the molten iron is poured into the ladle, sampling analysis is needed, and if the silicon content in the molten iron is higher than 0.8%, mixing is carried out to reduce the silicon content in the molten iron to be 0.8% or below; if the silicon content is not higher than 0.8 percent, the steps of converter smelting and coal gas recovery are carried out.
Further, converter smelting and coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
in the first stage, the converter smelts for 0 to 60 seconds, the converter alternately blows compressed air and powdered slag at the bottom and blows oxygen at the top of the converter, and when the oxygen content in the flue gas is less than a set value, the converter gas begins to be recycled.
Further, the pressure of bottom blowing compressed air is 0.1-0.15 Mpa/hole, and the flow rate is 50-80Nm 3 Min, top oxygen flow of 10000-12000m 3 The distance between the oxygen lance position and the steel liquid level is 2m;
the powdered slag charge comprises: lime powder and magnesium powder, wherein the bottom blowing lime powder is 8-10kg/t, and the bottom blowing magnesium powder is 3-5kg/t;
and setting that when the oxygen content in the flue gas is less than 1.5 percent, the converter gas is recovered.
Further, converter smelting and coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
and in the second stage, the converter blows for 61-300s, the punch material scrap steel is added for 15-20% from the high-level bin, the converter alternately blows oxygen from the bottom and powdered slag in sequence, and oxygen is blown from the top of an oxygen lance on the top of the converter.
Further, the pressure of bottom-blown oxygen is 0.2 Mpa/hole, the flow rate is 100-150Nm 3 Min, top oxygen flow rate of 18000-22000m 3 The distance between the oxygen lance position and the steel liquid level is 1.4-1.8m;
the powdered slag includes: lime powder and magnesium powder, wherein the bottom blowing lime powder is 4-5kg/t, and the bottom blowing magnesium powder is 2-3kg/t;
the thickness of the added punch scrap steel is 8-10mm, and the diameter is 4-6cm.
Further, converter smelting and coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas-powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
in the third stage, the converter blows for 301-650 seconds, 8-12% of punch scrap is added from a high-level bin, the converter alternately blows nitrogen and powdered slag at the bottom in sequence, and oxygen is blown at the top of the converter;
preferably, the pressure of bottom-blown nitrogen is 0.4-0.6 MPa/hole, and the flow rate is 150-200Nm 3 Min, top oxygen flow of 22000-30000m 3 The distance between the oxygen lance position and the steel liquid level is 1.4-1.8m;
the powdery slag charge is lime powder, and the bottom blowing lime powder is 4-5kg/t;
adding punch material with the thickness of 8-10mm and the diameter of 4-6cm.
Further, converter smelting and coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
in the fourth stage, blowing is carried out for 650 seconds till the end, 0-2% of punch scrap is added from a high-level bin, argon and powdery slag are blown at the bottom of a converter in sequence, and oxygen is blown at the top of the converter;
preferably, the pressure of bottom-blown argon is 0.2-0.3 Mpa/hole, and the flow rate is 80-120Nm 3 Min, top oxygen flow rate of 28000-32000 m 3 The distance between the oxygen lance position and the steel liquid level is 1.2-1.4m;
the powdery slag charge is lime powder, and the bottom blowing lime powder is 4-5kg/t;
the punch material is in a shape of a wafer, the thickness of the punch material is 8-10mm, and the diameter of the punch material is 4-6cm.
Due to the adoption of the technical scheme, the method has the following beneficial effects:
different types of waste steel are added in batches at different point positions through various processes such as cross bottom blowing gas, powdered slag charge, top blowing oxygen and the like, the whole process of converter smelting meets the coal gas recovery requirement under a large waste steel ratio mode, the coal gas of the converter is recovered in the whole process, and the recovery amount can be 200m 3 More than t, the average CO content can reach more than 48 percent, and conditions are created for improving the converter negative energy steelmaking level.
Detailed Description
The invention is further illustrated by the following examples:
a method for recycling converter gas in a large scrap ratio mode comprises the following steps:
s1: filling a metal material: adding scrap steel and molten iron into a converter in sequence according to a certain proportion, wherein in the embodiment, the proportion of the metal materials added into the metal materials fed into the converter in the steps of charging the metal materials into the converter, smelting the converter and recovering coal gas is 60-65%, and the proportion of the total scrap steel is 35-40%; the method specifically comprises the following steps:
s11: adding the crushed first batch of scrap steel into a ladle;
s12: pouring molten iron into a ladle after adding the first batch of scrap steel;
in steps S11 and S12, firstly adding the scrap steel to the bottom of the ladle, and then pouring the molten iron into the ladle, in this embodiment, before putting iron, a mechanical gripper is needed to crush the scrap steel, the crushed scrap steel accounts for 6-10% of the total scrap steel, and the height of the added crushed scrap steel does not exceed 1/2 of the total height of the ladle, so as to prevent the molten iron from spilling when the molten iron is loaded into the converter during converter smelting due to the lump of the scrap steel. The granularity of the crushed scrap added in the first batch is 20-30mm, the thickness is 3-5mm, the bulk density is light, and the rapid melting can be realized.
S13: and (3) after molten iron is injected into the ladle, sampling and analyzing, if the silicon content in the molten iron is higher than 0.8%, carrying out iron mixing to reduce the silicon content in the molten iron to be 0.8% or less, and if the silicon content is not higher than 0.8%, entering a converter smelting and coal gas recovery step.
In step S13 of this embodiment, the content of silicon in the molten iron is detected, specifically, the content of silicon in the molten iron may be detected by using a suitable measuring instrument or tool, such as a spectrometer, for example, which is not limited to what is protected by this embodiment and is relatively perfect in the prior art; the high-silicon molten iron is easy to cause large-scale splashing, is unfavorable for converter smelting, and can also have adverse effect on coal gas recovery, so sampling analysis is needed after iron discharge to detect the silicon content in the molten iron, and if the silicon content is higher than 0.8%, conceivably, the molten iron with the silicon content of less than 0.8% in the molten iron is injected during iron mixing operation, and the molten iron with the proper silicon content can be reasonably selected or prepared according to the site construction requirements.
In the process of mixing iron, the silicon content is 0.8 percent as a reference, 1 percent of steel bar end cutting scrap steel is added every time the silicon content is reduced by 0.1 percent, and the amount of the scrap steel added in the process is not more than 10 percent of the total amount of the scrap steel. The molten iron is transported to a converter for smelting according to each package, when the silicon content in the molten iron ladle is more than 0.8 percent, the molten iron is subjected to the package with lower silicon content, the mixed iron is carried out on the molten iron, and the adding amount of the scrap steel at the stage is determined according to the final silicon content of the molten iron. Scrap steel with a cut end is added in the process of mixing iron, and compared with light and thin broken scrap steel, the scrap steel can effectively avoid the phenomenon of lump formation due to the influence of self weight when being added.
S14: and (4) charging the first batch of scrap steel and molten iron into the converter, and starting converter smelting. In step S14 in this embodiment, scrap steel is not additionally added and the smelting process is directly performed.
S2: converter smelting and coal gas recovery: and (3) after the converter smelting is started, adopting a cross blowing mode to blow the gas powder mixture at the bottom, and if the converter recovery condition is met, beginning to recover converter gas until the converter smelting is finished. In the process, a cross bottom blowing mode is adopted, the bottom blowing sequence is air-powder, in the embodiment, a 6-hole bottom blowing mode is adopted, the diameter of a bottom blowing hole is 22mm, and the method specifically comprises the following steps:
s21, in the first stage, smelting for 0-60S in a converter, wherein the converter alternately blows compressed air and powdered slag at the bottom and blows oxygen at the top of the converter, and when the oxygen content in flue gas is less than a set value, the converter gas begins to be recycled.
Specifically, the pressure of the cross bottom blowing compressed air is 0.1-0.15 Mpa/hole, and the flow rate is 50-80Nm 3 Min, top oxygen flow of 10000-12000m 3 H is used as the reference value. In this embodiment, the bottom-blown powdered slag includes: lime powder and magnesium powder, wherein the bottom blowing lime powder is 8-10kg/t, and the bottom blowing magnesium powder is 3-5kg/t; in the embodiment, the granularity of the bottom blowing lime powder is less than or equal to 30mm, wherein the CaO content is more than 88 percent; the granularity of the magnesium powder is less than or equal to 30mm, the MgO content is more than 75%, the sequence of the lime powder and the magnesium powder is not limited when the powdery slag is bottom-blown, the lime powder is firstly bottom-blown and then the magnesium powder is bottom-blown, or the lime powder is firstly bottom-blown and then the magnesium powder is bottom-blown, the lime powder and the magnesium powder are adopted, the granularity is small, the metallurgical property is good, the material using amount in a large scrap ratio mode can be reduced, the loss of the material to the temperature of a molten pool is reduced, and the temperature of the molten pool is rapidly increased.
In the embodiment, the top-blown oxygen adopts an oxygen lance, the top-blown oxygen gun can be but not limited to a four-hole Laval gun, and the position of the oxygen lance is controlled to be 2 meters away from the liquid steel surface; the bottom blowing compressed air can realize direct contact between oxygen in the compressed air and the molten steel, and can be matched with stirring of a molten steel pool to carry out deoxidation reaction to generate flue gas with certain CO content, and the flue gas is purified and then recycled as converter gas. In the step S12, bottom blowing pure oxygen is not adopted, so that the reaction intensity of the molten pool can be controlled, and the oxygen purification cost is reduced to a certain extent. By adopting a top and bottom mixed gas supply mode, the early reaction kinetic condition is more sufficient, and the temperature of a molten pool is convenient to rise rapidly.
In the step S21, when the oxygen content in the flue gas is less than 1.5 percent, the converter gas is started to be recycled; and a top-bottom mixed gas supply mode is adopted, so that the oxygen content in the flue gas in the earlier stage is ensured to quickly meet less than 1.5%, the safety condition of converter recovery is further met, the flue gas is treated and recovered to obtain coal gas, and the recovery of the converter coal gas can be started. During the recovery process, the change trend of the oxygen content in the flue gas is concerned, the oxygen supply amount and the bottom blowing amount are dynamically adjusted, when the oxygen content is high, the oxygen lance position can be properly reduced, the oxygen supply amount of a top blowing oxygen lance can be reduced, the bottom blowing amount is increased, the increase of the CO content in the coal gas is promoted, and the requirement for recovering the converter coal gas is met as soon as possible.
S22, in the second stage, the converter blows for 61-300S, the temperature of the molten pool is further raised along with the oxidation of silicomanganese, the punch scrap is added from the high-position bin for 15-20%, the converter alternately blows oxygen and powdered slag at the bottom in sequence, and blows oxygen at the top of the converter, and the converter gas is continuously recovered in the stage.
Specifically, the punch scrap added at the stage has the thickness of 8-10mm and the diameter of 4-6cm. The pressure of bottom-blown oxygen is 0.2 Mpa/hole, the flow rate is 100-150Nm 3 Min, top oxygen flow rate of 18000-22000m 3 H; in this embodiment, the bottom-blown powdered slag includes: lime powder and magnesium powder, wherein the bottom blowing lime powder is 4-5kg/t, and the CaO content is more than 88%; 2-3kg/t of bottom-blown magnesium powder, wherein the MgO content is more than 75%; the sequence of lime powder and magnesium powder is not limited when the powdery slag is bottom-blown, and the lime powder and the magnesium powder can be bottom-blown firstly or bottom-blown firstly and then.
For realizing the full recovery of converter gas under big scrap ratio mode, the required scrap steel proportion of adding is higher at this in-process, it is low excessively to cause the molten bath temperature to hang down after avoiding once only adding the scrap steel, be unfavorable for going on of smelting, consequently add the disc shaped scrap steel in this stage in batches, thereby realize retrieving the purpose of converter gas under the big scrap steel proportion, simultaneously this stage is through adding disc shaped scrap steel, the surfacing can be through mode material loading such as hopper and vibratory feeder when impurity is few, high convenience and high speed, do not damage equipment.
In the embodiment, the top-blown oxygen adopts an oxygen lance, the top-blown oxygen gun can be but not limited to a four-hole Laval gun, and the position of the oxygen lance is controlled to be 1.4-1.8 meters away from the molten steel surface. During the recovery process, according to the oxygen content in the flue gas and the change trend of the CO content, the oxygen supply amount and the bottom blowing amount are dynamically adjusted, along with the oxidation of silicomanganese, the oxygen lance position of the oxygen lance can be properly reduced and the oxygen supply amount by top blowing oxygen can be reduced when the oxygen content is high, the bottom blowing amount is increased, and the increase of the CO content in the flue gas is promoted.
S23, in the third stage, the converter blows for 301-650 seconds, the silicon-manganese oxidation is basically finished, the reaction period of carbon-oxygen violent reaction is started, the temperature of a molten pool is further raised, the gas of the converter is recycled to enter a peak, 8-12% of punch material scrap steel is added from a high-level storage bin, the converter alternately blows nitrogen and powdered slag materials at the bottom, blows oxygen at the top of the converter, and the flue gas is continuously recycled in the stage. Specifically, the punch material added at the stage has the thickness of 8-10mm, the diameter of 4-6cm, the pressure of bottom blowing nitrogen of 0.4-0.6 Mpa/hole and the flow rate of 150-200Nm 3 Min, top oxygen flow of 22000-30000m 3 H; in the embodiment, the powdery slag material blown from the bottom is lime powder, the lime powder blown from the bottom is 4-5kg/t, and the content of CaO is more than 88%.
Similarly, in order to avoid the situation that the temperature of a molten pool is too low after scrap steel is added at one time and smelting is not facilitated, the wafer-shaped scrap steel is added in batches in the stage, so that the purpose of recycling converter gas under the condition of large scrap steel proportion is achieved, meanwhile, the wafer-shaped scrap steel is added in the stage, the surface is smooth while impurities are few, and the feeding can be realized in the modes of a hopper, a vibration feeder and the like, the operation is convenient and fast, and the equipment is not damaged.
In step S23 of this embodiment, oxygen is top blown by using the oxygen lance, the top blown oxygen gun can be, but is not limited to, a four-hole laval lance, and the lance position of the oxygen lance is controlled to be 1.4-1.8m from the molten steel surface. During the recovery process, dynamic adjustment is carried out according to the change trend of the content of CO in the flue gas, when the content of CO is low, the position of the oxygen lance can be reduced, the top-blown oxygen supply flow is increased, when the content of CO is high, the position of the oxygen lance can be increased, the top-blown oxygen supply flow is reduced, the content of CO is stably controlled by 40% -50%, the carbon-oxygen reaction rate in the molten pool is fed back through the content of CO, the reaction is stable and balanced, the smelting is more stable, and the quality of CO in the flue gas is higher.
S24: and in the fourth stage, blowing is finished for 650 seconds, the carbon-oxygen reaction is attenuated at the moment, the recovery peak value of the converter gas is gradually reduced, 0-2% of punch material scrap steel is added from a high-level bin, the converter sequentially blows argon and powdered slag at the bottom, blows oxygen at the top of the converter, and continues to recover the flue gas in the stage. Specifically, the thickness of the added punch material at the stage is 8-10mm, and the diameter is 4-6cm. The pressure of bottom blowing argon is 0.2-0.3 Mpa/hole, the flow is 80-120Nm 3 The top blowing oxygen gun adopts a four-hole Laval gun, and the top blowing oxygen flow is 28000 to 32000m 3 The distance between the oxygen lance position and the steel liquid level is 1.2-1.4m; in the embodiment, the powdery slag material blown from the bottom is lime powder, the lime powder blown from the bottom is 4-5kg/t, and the content of CaO is more than 88%; during the recovery process, the dynamic adjustment is carried out according to the change trend of the CO content in the flue gas, when the CO content is low, the lance position of the oxygen lance can be lowered and the top-blown oxygen supply flow can be increased, and when the CO content is high, the lance position of the oxygen lance can be increased and the top-blown oxygen supply flow can be lowered.
Example one
In this example, a 100-ton converter with an engineering capacity is taken as an example, and the structure production is performed according to the total charging amount of 100 tons, wherein the total weight of charged molten iron is 62 tons, the total weight of scrap steel is 38 tons, and the scrap steel ratio is 38%.
Before putting iron, 6 tons of crushed materials are loaded to the bottom of a ladle by a mechanical gripper, and then molten iron is poured.
Sampling and analyzing after the iron discharging is finished, wherein the silicon content in the molten iron is as follows: 0.60 percent and 1360 ℃ and 2 tons of steel bar end cutting scrap steel are added into the iron ladle.
The ladle containing a certain amount of scrap steel and molten iron is loaded into a converter and directly enters a converter smelting link without adding scrap steel.
Converter smelting is started, and a powder mixture is blown at the bottom of 6 holes in a cross blowing mode, namely gas-powder-gas-powder, wherein the diameter of a bottom blowing hole is 22mm.
In the first stage, blowing is started for 0-60s, a top-bottom mixed air supply mode is adopted, compressed air and powdery slag are blown from the bottom of the converter, the bottom blowing pressure is 0.1-0.15 Mpa/hole, and the bottom blowing flow is 50Nm 3 Min, wherein the powdery slag comprises: lime powder and magnesium powder, 8kg/t of bottom blowing lime powder and 3kg/t of magnesium powder, and a top blowing oxygen lance adopts four holesLaval gun with oxygen supply flow of 10000-12000m 3 And h, controlling the lance position of the oxygen lance to be 2 meters away from the molten steel surface. According to the change trend of the oxygen content in the flue gas, dynamically adjusting the oxygen supply amount and the bottom blowing amount, for example: when the oxygen content is high, the lance position of the oxygen lance can be properly reduced, the oxygen supply amount of the top-blowing oxygen lance can be reduced, the bottom blowing amount can be increased, the CO content in the flue gas can be promoted to be increased, the requirement of recovering the converter gas can be met as soon as possible, and when the oxygen content in the flue gas is less than 1.5%, the gas is recovered.
The second stage, blowing for 61-300s, further raising the temperature of the molten pool along with the oxidation of silicomanganese, adding 18 tons of punch scrap steel from a high-position storage bin, wherein the punch scrap is in a wafer shape, the thickness is 8-10mm, the diameter is 4-6cm, a top-bottom mixed gas supply mode is adopted, oxygen and powdery slag are blown from the bottom of a converter, the bottom blowing pressure is 0.2 Mpa/hole, and the bottom blowing flow is 100-150Nm 3 /min, wherein the powdered slag comprises: lime powder and magnesium powder, specifically, bottom blowing lime powder is 4kg/t, bottom blowing magnesium powder is 2.5kg/t, a top blowing oxygen gun adopts a four-hole Laval gun, and the oxygen supply flow is 18000-22000m 3 The oxygen lance position is controlled to be 1.4 to 1.8 meters away from the molten steel surface. According to the change trend of the oxygen content and the CO content in the flue gas, the oxygen content and the bottom blowing amount are dynamically adjusted, along with the oxidation of silicomanganese, when the oxygen content is high, the oxygen lance position of an oxygen lance can be properly reduced, the oxygen supply amount of top blowing oxygen is reduced, the bottom blowing amount is increased, and the increase of the CO content in the flue gas is promoted.
In the third stage, blowing is carried out for 301-650s, the oxidation of silicomanganese is basically finished, the reaction period of carbon-oxygen violent reaction is entered, the temperature of the molten pool is further raised, and the recovery of converter gas enters the peak. 10 tons of punch scrap steel are added from an overhead bin, the punch scrap is in a disc shape, the thickness is 8-10mm, and the diameter is 4-6cm. The top-bottom mixed gas supply mode is also adopted, nitrogen and powdery slag are blown at the bottom of the converter, the pressure is 0.4-0.6 Mpa/hole, the flow is 160Nm 3 The powder slag is lime powder, the bottom blowing lime powder is 4.5kg/t, the top blowing oxygen gun adopts a four-hole Laval gun, the oxygen supply flow is 22000-30000m 3 The lance position of the oxygen lance is controlled to be 1.4-1.8 meters away from the molten steel surface. The dynamic adjustment is carried out according to the change trend of the CO content of the flue gas, when the CO content is low, the lance position of the oxygen lance can be reduced and the top-blown oxygen supply flow can be improved, and when the CO content is high, the lance position of the oxygen lance can be improvedAnd the flow of top-blown oxygen supply is reduced, and the content of CO is stably controlled to be about 45 percent.
And in the fourth stage, blowing is carried out for 650s till the end, the carbon-oxygen reaction is attenuated, and the recovery peak value of the converter gas is gradually reduced. 2 tons of punch scrap steel are added into an overhead bin, the punch scrap is in a disc shape, the thickness of the punch scrap is 8-10mm, and the diameter of the punch scrap is 4-6 cm; adopting a top-bottom mixed gas supply mode, blowing argon and powdery slag at the bottom of the converter, wherein the pressure is 0.2-0.3 Mpa/hole, and the flow rate is 80-120Nm 3 Min, the powdery slag is lime powder, the bottom blowing lime powder is 4.5kg/t, the top blowing oxygen gun adopts a four-hole Laval gun, and the oxygen supply flow is 28000-32000 m 3 The position of the oxygen lance is controlled to be 1.2 to 1.4 meters away from the molten steel surface. According to the change trend of the CO content of the flue gas, the dynamic adjustment is carried out, and the gun position is properly reduced to promote the continuous CO content. During the recovery process, the dynamic adjustment is carried out according to the variation trend of the CO content in the flue gas, when the CO content is low, the oxygen lance position can be lowered, and the top-blown oxygen supply flow can be increased, and when the CO content is high, the oxygen lance position can be increased, and the top-blown oxygen supply flow can be lowered.
The embodiments of the present invention have been described in detail, but the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.
Claims (10)
1. A method for recovering converter gas in a large scrap ratio mode is characterized by comprising the following steps:
filling a metal material: adding scrap steel and molten iron into a converter in sequence according to a certain proportion;
converter smelting and coal gas recovery: and (3) adopting a cross blowing mode to blow a gas-powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished.
2. The method for recycling converter gas in the high scrap ratio mode according to claim 1, wherein in the steps of charging metal materials and converter smelting and gas recycling, the proportion of the total molten iron added into the foundry ladle is 60-65%, and the proportion of the total scrap is 35-40%.
3. The method for recovering converter gas in the high scrap ratio mode according to claim 2, wherein the metal charge is: the method for adding the scrap steel and the molten iron into the converter in sequence according to a certain proportion comprises the following steps:
adding the crushed first batch of scrap steel into the ladle;
pouring molten iron into a ladle after adding the first batch of scrap steel;
and (4) charging the first batch of scrap steel and molten iron into the converter, and starting converter smelting.
4. The method for recovering converter gas in the large scrap ratio mode according to claim 3, wherein the crushed scrap has a grain size of 20 to 30mm and a thickness of 3 to 5mm; adding the crushed scrap steel into a ladle until the height of the crushed scrap steel is not more than 1/2 of the height of the ladle;
after the molten iron is poured into the ladle, sampling analysis is needed, and if the silicon content in the molten iron is higher than 0.8%, mixing is carried out to reduce the silicon content in the molten iron to be 0.8% or below; if the silicon content is not higher than 0.8 percent, the steps of converter smelting and coal gas recovery are carried out.
5. The method for recovering converter gas in a high scrap ratio mode according to claim 1,
the converter smelting and the coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
in the first stage, the converter smelts for 0 to 60 seconds, the converter alternately blows compressed air and powdered slag at the bottom and blows oxygen at the top of the converter, and when the oxygen content in the flue gas is less than a set value, the converter gas begins to be recycled.
6. The method for recovering converter gas in a high scrap ratio mode according to claim 5,the pressure of bottom blowing compressed air is 0.1-0.15 Mpa/hole, the flow rate is 50-80Nm 3 Min, top oxygen flow of 10000-12000m 3 H, the distance between the oxygen lance position and the steel liquid level is 2m;
the powdered slag charge comprises: lime powder and magnesium powder, wherein the bottom blowing lime powder is 8-10kg/t, and the bottom blowing magnesium powder is 3-5kg/t;
and setting that when the oxygen content in the flue gas is less than 1.5 percent, the converter gas is recovered.
7. The method for recovering converter gas in a large scrap ratio mode according to claim 5 or 6,
the converter smelting and the coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
and in the second stage, the converter blows for 61-300s, the punch material scrap steel is added for 15-20% from the high-level bin, the converter alternately blows oxygen from the bottom and powdered slag in sequence, and oxygen is blown from the top of an oxygen lance on the top of the converter.
8. The method of claim 7, wherein the bottom-blown oxygen gas has a pressure of 0.2 MPa/hole and a flow rate of 100-150Nm 3 Min, top oxygen flow rate of 18000-22000m 3 The distance between the oxygen lance position and the steel liquid level is 1.4-1.8m;
the powdered slag includes: lime powder and magnesium powder, wherein the bottom blowing lime powder is 4-5kg/t, and the bottom blowing magnesium powder is 2-3kg/t;
the thickness of the added punch material scrap steel is 8-10mm, and the diameter is 4-6cm.
9. The method for recovering converter gas in a high scrap ratio mode according to claim 7,
the converter smelting and the coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
in the third stage, the converter blows for 301-650 seconds, 8-12% of punch scrap is added from a high-level bin, the converter alternately blows nitrogen and powdered slag at the bottom in sequence, and oxygen is blown at the top of the converter;
preferably, the pressure of bottom-blown nitrogen is 0.4-0.6 MPa/hole, and the flow rate is 150-200Nm 3 Min, top oxygen flow of 22000-30000m 3 The distance between the oxygen lance position and the steel liquid level is 1.4-1.8m;
the powdery slag charge is lime powder, and the bottom blowing lime powder is 4-5kg/t;
adding punch material with the thickness of 8-10mm and the diameter of 4-6cm.
10. The method for recovering converter gas in a high scrap ratio mode according to claim 3,
the converter smelting and the coal gas recovery: the method comprises the following steps of adopting a cross blowing mode to blow a gas powder mixture at the bottom after the smelting of the converter is started, and if the recovery condition of the converter is met, starting to recover converter gas until the smelting of the converter is finished:
in the fourth stage, blowing is carried out for 650 seconds till the end, 0-2% of punch scrap is added from a high-level bin, argon and powdery slag are blown at the bottom of a converter in sequence, and oxygen is blown at the top of the converter;
preferably, the pressure of bottom-blown argon is 0.2-0.3 Mpa/hole, the flow rate is 80-120Nm 3 Min, top-blown oxygen flow rate of 28000-32000 m 3 The distance between the oxygen lance position and the steel liquid level is 1.2-1.4m;
the powdery slag charge is lime powder, and the bottom blowing lime powder is 4-5kg/t;
the punch material is in a shape of a wafer, the thickness of the punch material is 8-10mm, and the diameter of the punch material is 4-6cm.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211536481.9A CN115874008A (en) | 2022-12-02 | 2022-12-02 | Method for recycling converter gas in large scrap ratio mode |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211536481.9A CN115874008A (en) | 2022-12-02 | 2022-12-02 | Method for recycling converter gas in large scrap ratio mode |
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| CN115874008A true CN115874008A (en) | 2023-03-31 |
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| CN202211536481.9A Pending CN115874008A (en) | 2022-12-02 | 2022-12-02 | Method for recycling converter gas in large scrap ratio mode |
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