CN116640904A - Method for preparing powder by recycling slag through double-stage smelting bottom injection of converter and application - Google Patents
Method for preparing powder by recycling slag through double-stage smelting bottom injection of converter and application Download PDFInfo
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- CN116640904A CN116640904A CN202310604642.1A CN202310604642A CN116640904A CN 116640904 A CN116640904 A CN 116640904A CN 202310604642 A CN202310604642 A CN 202310604642A CN 116640904 A CN116640904 A CN 116640904A
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- 239000000843 powder Substances 0.000 title claims abstract description 206
- 239000002893 slag Substances 0.000 title claims abstract description 138
- 238000003723 Smelting Methods 0.000 title claims abstract description 54
- 238000000034 method Methods 0.000 title claims abstract description 47
- 238000002347 injection Methods 0.000 title claims abstract description 42
- 239000007924 injection Substances 0.000 title claims abstract description 42
- 238000004064 recycling Methods 0.000 title claims abstract description 15
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 claims abstract description 49
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 claims abstract description 49
- 239000000292 calcium oxide Substances 0.000 claims abstract description 49
- 238000005261 decarburization Methods 0.000 claims abstract description 33
- 238000002161 passivation Methods 0.000 claims abstract description 22
- 238000009628 steelmaking Methods 0.000 claims abstract description 12
- 238000010298 pulverizing process Methods 0.000 claims abstract description 6
- 238000007664 blowing Methods 0.000 claims description 167
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 74
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 claims description 70
- 238000005507 spraying Methods 0.000 claims description 69
- 239000007789 gas Substances 0.000 claims description 37
- 229910052757 nitrogen Inorganic materials 0.000 claims description 37
- 229910052786 argon Inorganic materials 0.000 claims description 35
- 229910052698 phosphorus Inorganic materials 0.000 claims description 20
- 239000011574 phosphorus Substances 0.000 claims description 20
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 18
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 18
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 18
- 229910052799 carbon Inorganic materials 0.000 claims description 18
- 229910052760 oxygen Inorganic materials 0.000 claims description 18
- 239000001301 oxygen Substances 0.000 claims description 18
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 17
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical group C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 claims description 17
- 229910052717 sulfur Inorganic materials 0.000 claims description 17
- 239000011593 sulfur Substances 0.000 claims description 17
- 239000011812 mixed powder Substances 0.000 claims description 15
- 238000002156 mixing Methods 0.000 claims description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 239000002245 particle Substances 0.000 claims description 6
- 238000003860 storage Methods 0.000 claims description 6
- 238000005262 decarbonization Methods 0.000 abstract description 18
- 238000000227 grinding Methods 0.000 abstract description 14
- 238000005516 engineering process Methods 0.000 abstract description 13
- 230000000694 effects Effects 0.000 abstract description 10
- 239000000463 material Substances 0.000 abstract description 10
- 238000005272 metallurgy Methods 0.000 abstract description 2
- 229910052751 metal Inorganic materials 0.000 abstract 1
- 239000002184 metal Substances 0.000 abstract 1
- 239000012159 carrier gas Substances 0.000 description 32
- 229910000831 Steel Inorganic materials 0.000 description 26
- 239000010959 steel Substances 0.000 description 26
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 22
- 230000000052 comparative effect Effects 0.000 description 15
- 230000008569 process Effects 0.000 description 13
- 229910052742 iron Inorganic materials 0.000 description 11
- 238000010079 rubber tapping Methods 0.000 description 8
- 239000007921 spray Substances 0.000 description 7
- 239000010935 stainless steel Substances 0.000 description 6
- 229910001220 stainless steel Inorganic materials 0.000 description 6
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 5
- 235000011941 Tilia x europaea Nutrition 0.000 description 5
- 239000004571 lime Substances 0.000 description 5
- 230000001105 regulatory effect Effects 0.000 description 5
- 239000002131 composite material Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- 239000002994 raw material Substances 0.000 description 4
- 230000003749 cleanliness Effects 0.000 description 3
- 238000006477 desulfuration reaction Methods 0.000 description 3
- 230000023556 desulfurization Effects 0.000 description 3
- 238000007599 discharging Methods 0.000 description 3
- 238000002360 preparation method Methods 0.000 description 3
- 238000011084 recovery Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- UNLRVSBRNJYNHN-UHFFFAOYSA-N [cyano-(3-phenoxyphenyl)methyl] 2-(4-chlorophenyl)-3-methylbutanoate;dimethoxy-(4-nitrophenoxy)-sulfanylidene-$l^{5}-phosphane Chemical compound COP(=S)(OC)OC1=CC=C([N+]([O-])=O)C=C1.C=1C=C(Cl)C=CC=1C(C(C)C)C(=O)OC(C#N)C(C=1)=CC=CC=1OC1=CC=CC=C1 UNLRVSBRNJYNHN-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 230000001276 controlling effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000010410 dusting Methods 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000010310 metallurgical process Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 238000011112 process operation Methods 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000005728 strengthening Methods 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
- C21C7/0645—Agents used for dephosphorising or desulfurising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/34—Blowing through the bath
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/068—Decarburising
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention belongs to the technical field of converter steelmaking injection metallurgy, and discloses a method for preparing powder by recovering slag through bottom injection in converter double-stage smelting and application thereof. And (3) recycling, sorting and grinding the dephosphorization slag and the decarburization slag for standby. And in the dephosphorization period, dephosphorization slag powder and passivation calcium oxide powder are sprayed into the converter from the bottom of the converter. And in the deep decarburization stage, decarburized slag powder and passivated calcium oxide powder are sprayed into the converter from the bottom of the converter. The example results show that the converter double-stage smelting bottom-injection recycled slag pulverizing technology has better dephosphorization and decarbonization effects, low material consumption and high metal yield compared with the converter reserved decarbonization slag technology under the same condition and the existing bottom-injection powder.
Description
Technical Field
The invention relates to the technical field of converter steelmaking injection metallurgy, in particular to a method for preparing powder by recovering slag through double-stage smelting bottom injection of a converter and application thereof.
Background
With the increasing development of the steel industry, the steel yield is remarkably improved, and higher requirements are put on the quality of steel, so that the production of high-quality clean steel is urgent. The trend of energy supply is increasingly tense, which requires a higher level of steelmaking energy-saving technology, and the cost reduction and quality improvement become important tasks, and the dephosphorization efficiency of the converter is particularly important. In the production of general steel grades, phosphorus as an impurity element greatly influences the low-temperature impact toughness of steel, obviously reduces the performance of the steel, and dephosphorization in a converter is an important link in the steelmaking process. At home and abroad, the converter steelmaking dephosphorization process mainly comprises three types: single slag method, double slag method and double linkage method. The single slag method is simple, slag forming, desilication and dephosphorization are carried out once, but the metallurgical functions for producing low-phosphorus steel are insufficient. The double slag method is used for implementing two-step metallurgical process, slag is firstly formed for dephosphorization, part of slag is poured out, and then feeding, decarburization and heating are carried out. The duplex method is used for carrying out independent dephosphorization and decarburization processes through two large converters respectively. Although the double slag method and the double-linkage method can meet the smelting requirement, the production cost is increased, and the smelting period is prolonged. The converter bottom powder spraying technology sprays materials from the bottom of the converter, can quickly realize the uniform stirring of a converter molten pool, greatly promote slag steel balance, reduce carbon and oxygen accumulation of molten steel at a terminal point, and improve decarburization, dephosphorization and desulfurization efficiency of the converter, thereby reducing steel material consumption, slag forming material consumption and deoxidization alloy consumption of a converter steelmaking process and obviously improving molten steel cleanliness.
In the prior art for recycling converter slag, the utilization rate of the converter slag is low, and the converter slag is generally added into a converter together with a slag former, so that the dephosphorization and decarburization functions of the converter slag cannot be effectively utilized. The converter slag is sprayed into the converter by using the converter bottom powder spraying technology, so that good dephosphorization and decarbonization dynamics and thermodynamic conditions are provided, the current requirement for improving the cleanliness of the converter is well met, the process operation is reduced, the production cost is saved, and a good metallurgical effect is achieved. Therefore, the development force of the converter bottom powder spraying technology is increased, the practical experience of the converter bottom powder spraying technology is enriched, and the realization of efficient dephosphorization and decarburization of the converter and low-cost smelting becomes one of the important directions of converter steelmaking development in China.
The invention patent CN103773919A of Jiaqing et al proposes a method for smelting medium and high-phosphorus molten iron in a converter, wherein the smelting is divided into desilication, dephosphorization and less slag smelting decarburization periods of the molten iron, lime powder is sprayed into a molten pool, the contact area of molten steel and dephosphorization materials is increased, and dephosphorization reaction between slag steels is promoted. Wang Deyong and other patent CN113234883a proposes a smelting process of bottom blowing powder injection of a converter, in which a bottom blowing spray gun is installed at the bottom of the converter, high-pressure nitrogen and argon are used as carriers, powder required by the smelting of the converter is sprayed into the converter from the bottom blowing spray gun, the sprayed powder participates in oxidation reaction in the converter, and the addition amount of slag at the top is reduced, so that the total slag amount is reduced. The traditional single slag method steelmaking dephosphorization is improved through different methods, but the bottom spraying process is limited to dephosphorization strengthening bath stirring, and has no specific scheme on how to realize lime powder spraying to a bath, and the influence of slag powder is not considered; only lime powder is smelted and blown in the converter, metallurgical functions in different periods are not considered, and dephosphorization and decarburization effects are not obvious.
In the top-bottom combined blown converter process, argon or nitrogen is used as carrier gas, and the composite dephosphorization powder is sprayed into the converter from the bottom of the converter through a bottom spraying device to carry out deep dephosphorization. Meanwhile, the smelting period of the converter is divided into a deep dephosphorization period and a deep decarburization period, slag materials in different periods are recovered for powder making and recycling, and the slag materials are mixed with passivated calcium oxide powder according to a certain proportion, so that the deep dephosphorization and deep decarburization effects in different smelting periods are improved.
Disclosure of Invention
The invention aims to provide a method for preparing powder by recycling slag through double-stage smelting bottom injection of a converter and application of the method, wherein molten steel with higher cleanliness, lower material consumption and better decarburization and desulfurization, and particularly dephosphorization effects can be obtained through the method.
In order to achieve the above object, the present invention has the following technical scheme: a method for preparing powder by recovering slag through double-stage smelting bottom injection of a converter specifically comprises the following steps:
recovering dephosphorized slag and decarburized slag of a converter, classifying to prepare powder, and respectively mixing the powder with passivated calcium oxide powder according to a certain weight ratio; the smelting deep dephosphorization stage adopts a top-blowing oxygen soft blowing mode, and the smelting deep decarburization stage adopts a top-blowing conventional mode; and (3) performing bottom blowing in the whole smelting period, taking argon or nitrogen as a carrier, and blowing mixed powder at the bottom of a converter 9 through a bottom blowing element 8.
The mixed powder is dephosphorized slag powder and passivated calcium oxide powder in a deep dephosphorization period, and is decarburized slag powder and passivated calcium oxide powder in a deep decarburization period.
The mixed powder is specifically characterized in that the weight ratio of dephosphorization slag powder in the deep dephosphorization stage to passivation calcium oxide powder is [ 1-10 ] [ 1-5 ], and the weight ratio of decarburization slag powder in the deep decarburization stage to passivation calcium oxide powder is [ 1-10 ] [ 1-5 ].
The mixed powder injection speed v of the dephosphorization slag powder and the passivation calcium oxide powder 1 Range 0<v 1 Less than or equal to 1500kg/min; the mixed powder injection speed v of the decarburized slag powder and the passivated calcium oxide powder 2 Range 0<v 2 Less than or equal to 1500kg/min; the particle size range of the mixed powder is 200-2000 meshes.
The flow rate of the bottom blowing argon or nitrogen ranges from 0.02 to 1.50Nm 3 /min/t; the deep dephosphorization period adopts a soft blowing mode, and the flow range is 2.5-3.5 Nm 3 /min/t; the deep decarbonization period adopts a conventional mode, and the flow range is 3.5-4.5 Nm 3 /min/t。
The mass ratio of the mixed powder to the powder gas of the bottom blowing gas is 10.0-50.0.
The bottom blowing is realized based on a converter double-stage smelting bottom blowing recycled slag powder making and spraying device, and comprises a gas storage bottle 1, a gas tank 2, an oil-water separator 3, a feeding bin 5, a pressurizing powder spraying tank 6, a discharging control valve 7, a bottom blowing element 8 and a converter 9; the inlet of the gas storage bottle 1, the gas tank 2 and the inlet of the oil-water separator 3 are sequentially connected through a control valve; the outlet of the oil-water separator 3 is divided into a plurality of branches, a pressure gauge and a flowmeter 4 are arranged on each branch, and all the branches are connected to a pressurizing powder spraying tank 6; an upper bin 5 is arranged above the pressurizing powder spraying tank 6; the bottom end of the pressurizing powder injection tank 6 is connected with a blanking control valve 7, and the discharging control valve and the lowest branch are connected to the bottom end of a bottom blowing element 8, and the bottom blowing element 8 is connected with the bottom end of a converter 9.
The bottom nozzles of the bottom blowing element (8) are arranged circumferentially, the diameter of the circumference being 1/2 of the diameter of the bath; the bottom nozzle is provided with two groups, and the included angle between each group is 30 degrees or 90 degrees.
The method is applied to the converter steelmaking process, and the final carbon oxygen concentration, carbon content, phosphorus content and sulfur content are obtained according to the method.
Advantageous effects of the inventionThe effect is as follows: compared with the traditional converter steelmaking process and other converter bottom powder spraying technologies, the invention has stronger adaptability to smelting process conditions, realizes the reduction of lime consumption by more than 30 percent, reduces iron and steel material consumption by more than 8kg/t, and has the endpoint carbon-oxygen area range of 1.0 multiplied by 10 -4 ～2.0×10 -3 Endpoint carbon content [ C]In the range of 0.02 to 0.03 percent, the end point sulfur content S]In the range of 0.001 to 0.01 percent, and the end point phosphorus content [ P ]]The range is 0.001-0.005%, the service life of the bottom blowing element is 3000-5000 furnace, and the benefit of ton steel can be improved by more than 5%.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a schematic diagram of the experimental setup of the present invention.
FIG. 3 (a) is a schematic view of a bottom blowing element arrangement at 30;
FIG. 3 (b) is a schematic view of a bottom blowing element arrangement at 90;
fig. 4 is a schematic view of a bottom blowing element.
In the figure: 1. the device comprises a gas storage bottle, a gas tank, a gas-oil separator, a pressure gauge, a flowmeter, a feeding bin, a pressurizing powder spraying tank, a discharging control valve, a bottom blowing element, a converter and a converter.
Detailed Description
The invention provides a method for preparing powder by recovering slag through bottom spraying in double-stage smelting of a converter and application thereof. In a specific embodiment of the invention, the capacity of the converter is 20-400 t. Comprises the following steps:
fig. 1 is a process flow diagram, and the arrow direction is the process flow direction. The method mainly comprises a deep dephosphorization period and a deep decarburization period, wherein dephosphorization slag and decarbonization slag are respectively recovered, and the materials are ground into fine powder for standby, so that the recycling of slag powder is realized. The invention systematically classifies and recycles the dephosphorized slag and the decarbonized slag of the converter produced by the conventional converter, sorts the dephosphorized slag and ventilates and dries the dephosphorized slag. And then uniformly mixing the dried converter dephosphorization slag, the decarbonization slag and the passivated calcium oxide powder according to a certain weight ratio, and grinding. Using stainless steel single tube bottom blowing elements 8, with constant air flow at different stagesAnd (5) spraying and blowing mixed slag powder at a flow rate. The blowing flow rate of the bottom blowing carrier gas ranges from 0.02 Nm to 1.50Nm 3 The powder spraying flow is 0-1500 kg/min. In the deep dephosphorization period, a top-blown soft blowing mode is adopted, and the top-blown oxygen flow rate of the oxygen lance at the top of the converter is 2.5-3.5 Nm 3 In the deep decarbonization period, top blowing normal mode is adopted, and the top blowing oxygen flow rate is 3.5-4.5 Nm 3 /min/t。
FIG. 4 is a schematic view of a bottom blowing element through which secondary gas is introduced into the molten pool via the circumferential weld to act as a bottom blowing stirrer and a bottom blowing element. The auxiliary blowing amount is in the range of 0.10-0.50 Nm 3 /min/t。
The method comprises the following specific steps:
early preparation: and (3) systematically classifying and recycling the dephosphorized slag and decarbonized slag of the converter produced by the conventional converter, sorting and ventilating and drying. And then uniformly mixing the dried converter dephosphorization slag and decarburization slag with passivated calcium oxide powder according to different proportions, and grinding for later use.
The powder spraying operation control process comprises the following steps:
firstly, opening a pressurizing valve, and increasing the pressure in the pressurizing powder spraying tank to 0.50-0.55 MPa.
Charging period: nitrogen-blowing protection powder spraying element for charging scrap steel into converter and adding molten iron, and auxiliary blowing flow rate of 0.05-0.50 Nm 3 Per minute/t, the carrier gas flow rate is 0.05-0.50 Nm 3 /min/t。
Deep dephosphorization period: the top-blown soft blowing mode is adopted, and the top-blown oxygen flow of the oxygen lance at the top of the converter is 2.5-3.5 Nm 3 /min/t. The dephosphorization slag powder and the passivation calcium oxide powder are uniformly mixed according to a certain weight ratio, ground to the required particle size, and blown with argon or nitrogen for 30 seconds before blowing to protect the bottom blowing element, wherein the gas flow is the same as the charging period, so as to protect the bottom blowing element and promote the temperature rise of molten iron in a furnace. Blowing for 30 seconds to start powder spraying, wherein the powder spraying flow is 45-750 kg/min, and the carrier gas flow is 0.50-0.75 Nm 3 Per min/t, the auxiliary blowing flow is 0.10-0.50 Nm 3 /min/t. And adjusting smelting time and powder spraying flow according to the temperature of the molten pool. The powder spraying flow is regulated to be 50-1000 kg/min according to the temperature of the converter, and the carrier gas flow is 0.75-1.50 Nm 3 Per min/t, the auxiliary blowing flow is 0.10-0.50 Nm 3 /min/t。
Recovering dephosphorized slag: after the dephosphorization period is over, bottom blowing argon or nitrogen protects the bottom blowing element, and dephosphorization slag is poured from the furnace mouth, recovered, separated and ground for standby.
Deep decarbonization period: adopts a top-blown normal mode, and the top-blown oxygen flow range is 3.5-4.5 Nm 3 /min/t. Switching powder to spray decarbonized slag powder and passivated calcium oxide powder, wherein the powder spraying flow is regulated to be 50-1000 kg/min according to the temperature of a converter, and the carrier gas flow is 0.75-1.50 Nm 3 Per min/t, the auxiliary blowing flow is 0.10-0.50 Nm 3 /min/t。
And (3) in the later stage of smelting: the powder spraying amount is reduced to 25-500 kg/min, and the carrier gas flow is 0.50-0.75 Nm 3 Per min/t, the auxiliary blowing flow is 0.10-0.50 Nm 3 /min/t. Stopping powder injection 1min before blowing, and bottom blowing argon or nitrogen to protect the bottom blowing element, wherein the tapping time is determined according to the temperature of the final molten steel, the final carbon oxygen content, the final carbon content, the final sulfur content, the final phosphorus content and the like.
Recovering the decarbonization slag: after the decarburization period is over, bottom blowing argon or nitrogen protects the bottom blowing element, dumping the carbon-removed slag from the furnace mouth, recycling, sorting and grinding for standby.
During tapping, argon or nitrogen is adopted to protect the bottom blowing element, and the auxiliary blowing flow is 0.10-0.50 Nm 3 Per minute/t, the carrier gas flow rate is 0.05-0.50 Nm 3 And (5) per minute/t, and finishing one smelting cycle.
The pressure of a gas inlet of the converter double-stage smelting bottom-spraying recycled slag pulverizing method is 0.5-1.2 MPa.
The particle size of the mixed powder can be 200-2000 meshes.
Fig. 2 is a schematic diagram of an implementation device, with arrows indicating the direction of gas flow. The device for preparing powder from the recycled slag powder by double-stage smelting bottom injection of the converter is specifically applied to the following steps: the gas storage bottle 1 is connected with the gas tank 2, argon or nitrogen is blown through the oil-water separator 3, and the pressure gauge and the flowmeter 4 are used for controlling the gas flow and the pressure; powder enters a pressurizing powder spraying tank 6 from a feeding bin 5, argon or nitrogen is introduced into the pressurizing powder spraying tank 6, a pressure gauge and a flowmeter 4 are connected, the flow and the pressure of the powder are controlled, and finally, a mixture of gas and powder is introduced into a bottom blowing element 8 and sprayed into a converter 9. The gas and powder mixture sprayed into the converter 9 can be quickly stirred into the molten pool, so that the components of the molten pool are uniform, and a better smelting effect is achieved. The blown passivated calcium oxide powder can be used for fast slagging, promote the balance of steel slag and reduce the consumption of lime. The blown argon or nitrogen can fully stir the molten pool, so as to achieve better desulfurization and dephosphorization effects. Meanwhile, the preparation method provided by the invention is simple, the preparation period is short, and the equipment investment is low.
The bottom blowing element 8 is a buried stainless steel single tube with a diameter ranging from 6mm to 25mm.
The invention also provides an application of the converter double-period smelting bottom-spraying recycled slag pulverizing method. The endpoint carbon oxygen volume, endpoint carbon content, endpoint sulfur content and endpoint phosphorus content are important performance parameters of converter steelmaking, and the lower the value is, the better the smelting effect is. The results of the example show that the end point carbon-oxygen area range of the converter bottom powder spraying technology in the invention is 1.0x10 in the converter application test -4 ～2.0×10 -3 Endpoint carbon content [ C]In the range of 0.02 to 0.03 percent, the end point sulfur content S]In the range of 0.001 to 0.01 percent, and the end point phosphorus content [ P ]]The range is 0.001-0.005%, and the service life of the bottom blowing element is 3000-5000.
FIG. 3 shows a bottom blowing element arrangement with bottom feed gas arranged on the circumference of the bath 0.5-0.6D (D is bath diameter). Fig. 4 is a schematic view of a bottom blowing element, which is a stainless steel single tube.
The invention carries out ball milling and grinding on the passivated calcium oxide powder to obtain powder with uniform particle size distribution. The source of the raw material of the passivated calcium oxide powder is not particularly required, and the product with purity of more than 99.9% is commercially available. In the present invention, the particle size of the raw material of the passivated calcium oxide powder is preferably less than 200 mesh, more preferably less than 400 mesh, and most preferably 1340-2000 mesh.
In the present invention, the source of the argon or nitrogen raw material is not subject to any special requirement, and commercially available products known to those skilled in the art are adopted; specifically, the argon or nitrogen feedstock preferably has a purity of greater than 99.99%.
In the present invention, the source of the nitrogen raw material is not subject to any special requirement, and the commercial products known to those skilled in the art can be used; specifically, the nitrogen feedstock preferably has a purity of greater than 99.99%.
In the present invention, the powder-gas ratio of the passivated calcium oxide powder to argon or nitrogen is preferably 10 to 50, and most preferably 20 to 35.
The following describes the method and application of the converter double-stage smelting bottom-injection recycled slag pulverizing technology in detail by combining examples, but the method and application are not to be construed as limiting the protection scope of the invention.
Example 1
And (3) systematically classifying and recycling the dephosphorized slag and decarbonized slag of the converter produced by the conventional converter, sorting and ventilating and drying. And then respectively mixing the dried converter dephosphorization slag and decarburization slag with passivated calcium oxide powder according to the weight ratio of 1:5, uniformly mixing and grinding.
The length of the bottom blowing nozzle is 0.8m, the bottom blowing nozzle is a stainless steel seamless pipe, and the size is 800mm by 6mm.
The bottom blowing element according to the embodiment is applied to a 20 ton converter, 4 bottom blowing elements according to the embodiment are arranged at the bottom of the converter, and the maximum flow rate of argon or nitrogen blown by the bottom blowing element is controlled to be 0.14Nm 3 The maximum flow rate of the injection dephosphorization slag powder and the passivation calcium oxide powder is 50kg/min, the maximum flow rate of the injection decarburization slag powder and the passivation calcium oxide powder is 50kg/min, the gas ratio of the injection powder is 10, and the inlet pressure of the powder gas is 0.8-1.2 MPa.
The powder spraying operation control process comprises the following steps: first, the pressurization valve was opened, and the pressure in the pressurization tank was increased to 0.55MPa.
Charging period: nitrogen-blowing protection powder spraying element for charging scrap steel into converter and adding molten iron, and carrier gas flow rate is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 /min/t。
Deep dephosphorization period: the top-blown soft blowing mode is adopted, and the top-blown oxygen flow rate of the oxygen lance at the top of the converter is 2.5Nm 3 /min/t. Argon or nitrogen is blown for 30 seconds before blowing to protect the bottom blowing element, the gas flow is the same as the charging period, and the purpose is to protect the bottom blowing element and promote the temperature rise of molten iron in the furnace. Blowing for 30 secondsThe composite slag powder is sprayed, the powder spraying flow is 45kg/min, and the carrier gas flow is 0.13Nm 3 Per min/t, auxiliary blowing flow 0.13Nm 3 /min/t. And adjusting smelting time and powder spraying flow according to the temperature of the molten pool. The powder spraying flow is regulated to 50kg/min according to the temperature of the converter, and the carrier gas flow is 0.14Nm 3 Per min/t, the auxiliary blowing flow was 0.14Nm 3 /min/t。
Recovering dephosphorized slag: after the dephosphorization period is over, bottom blowing argon or nitrogen is used for protecting the bottom blowing element, dephosphorization slag is poured from a furnace mouth, the dephosphorization slag is recovered and separated, and the carrier gas flow is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 And/min/t, and grinding for standby.
Deep decarbonization period: in the top-blown normal mode, the top-blown oxygen flow rate was in the range of 3.5Nm 3 /min/t. Switching powder spraying and blowing passivation calcium oxide powder, wherein the powder spraying flow is adjusted to 50kg/min according to the temperature of the converter, and the carrier gas flow is 0.14Nm 3 The auxiliary blowing flow rate per min/t was 0.14Nm 3 /min/t。
And (3) in the later stage of smelting: the powder spraying amount is reduced to 25kg/min, and the carrier gas flow rate is 0.07Nm 3 Per min/t, auxiliary blowing flow 0.07Nm 3 /min/t. Stopping powder injection 1min before blowing, and bottom blowing argon or nitrogen to protect the bottom blowing element, wherein the tapping time is determined according to the temperature of the final molten steel, the final carbon oxygen content, the final carbon content, the final sulfur content, the final phosphorus content and the like.
Recovering the decarbonization slag: after the decarburization period was completed, the bottom-blowing element was purged with argon or nitrogen at a carrier gas flow rate of 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 Pouring the decarbonization slag from the furnace mouth, recovering, sorting and grinding for standby.
During tapping, argon or nitrogen is adopted to protect the bottom blowing element, and the carrier gas flow is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 And (5) per minute/t, and finishing one smelting cycle.
The implementation results show that: after a 20-ton converter uses the converter bottom powder spraying technology of the invention, the final carbon-oxygen area is 2.0x10 -3 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.03 ]]End point phosphorus content [ P ] of 0.01 ]]0.005% and the service life of the bottom blowing element is 3000 furnace.
Example 2
And (3) systematically classifying and recycling the dephosphorized slag and decarbonized slag of the converter produced by the conventional converter, sorting and ventilating and drying. And then respectively mixing the dried converter dephosphorization slag and converter decarburization slag powder with passivated calcium oxide powder according to the weight ratio of 2:1, uniformly mixing and grinding.
The length of the bottom blowing nozzle is 1.1 m, the bottom blowing nozzle is a stainless steel seamless pipe, and the size is 1000mm x 12mm.
The bottom blowing element according to the embodiment is applied to a 100 ton converter, 4 bottom blowing elements according to the embodiment are arranged at the bottom of the converter, and the maximum flow rate of argon or nitrogen blown by the bottom blowing element is controlled to be 0.07Nm 3 The maximum flow rate of the dephosphorization slag powder and the passivation calcium oxide powder is 600kg/min, the maximum flow rate of the decarburization slag powder and the passivation calcium oxide powder is 600kg/min, the gas ratio of the powder is 50, and the inlet pressure of the powder gas is 0.5-0.8 MPa.
The powder spraying operation control process comprises the following steps: first, the pressurizing valve was opened, and the pressure in the pressurizing tank was increased to 0.50MPa.
Charging period: nitrogen-blowing protection powder spraying element for charging scrap steel into converter and adding molten iron, and carrier gas flow rate is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 /min/t。
Deep dephosphorization period: the top-blown soft blowing mode is adopted, and the top-blown oxygen flow rate of the oxygen lance at the top of the converter is 3.0Nm 3 /min/t. Argon or nitrogen is blown for 30 seconds before blowing to protect the bottom blowing element, the gas flow is the same as the charging period, and the purpose is to protect the bottom blowing element and promote the temperature rise of molten iron in the furnace. Spraying composite slag powder after blowing for 30 seconds, wherein the powder spraying flow is 400kg/min, and the carrier gas flow is 0.05Nm 3 Per min/t, auxiliary blowing flow 0.1Nm 3 /min/t. And adjusting smelting time and powder spraying flow according to the temperature of the molten pool. The powder spraying flow rate is regulated to 600kg/min according to the temperature of the converter, and the carrier gas flow rate is 0.07Nm 3 Per min/t, auxiliary blowing flow 0.1Nm 3 /min/t。
Recovering dephosphorized slag: after the dephosphorization period is over, bottom blowing argon or nitrogen is used for protecting the bottom blowing element, dephosphorization slag is poured from the furnace mouth, the dephosphorization slag is recovered and separated, and the carrier gas flow is 500Nm 3 /h, auxiliary blowing flow 400Nm 3 And/h, grinding for standby.
Deep decarbonization period: in the top-blown normal mode, the top-blown oxygen flow rate was in the range of 4.0Nm 3 /min/t. Switching powder spraying and blowing passivation calcium oxide powder, wherein the powder spraying flow is regulated to 600kg/min according to the temperature of the converter, and the carrier gas flow is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 /min/t。
And (3) in the later stage of smelting: the powder spraying amount is reduced to 300kg/min, and the carrier gas flow rate is 0.03Nm 3 Per min/t, auxiliary blowing flow 0.1Nm 3 /min/t. Stopping powder injection 1min before blowing, and bottom blowing argon or nitrogen to protect the bottom blowing element, wherein the tapping time is determined according to the temperature of the final molten steel, the final carbon oxygen content, the final carbon content, the final sulfur content, the final phosphorus content and the like.
Recovering the decarbonization slag: after the decarburization period was completed, the bottom-blowing element was purged with argon or nitrogen at a carrier gas flow rate of 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 Pouring the decarbonization slag from the furnace mouth, recovering, sorting and grinding for standby.
During tapping, argon or nitrogen is adopted to protect the bottom blowing element, and the carrier gas flow is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 And (5) per minute/t, and finishing one smelting cycle.
The implementation results show that: after a 100 ton converter uses the converter bottom powder spraying technology of the invention, the final carbon-oxygen area is 1.0x10 -3 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.028 ]]0.008% end point phosphorus content [ P]0.004%, and the service life of the bottom blowing element is 4000 furnaces.
Example 3
And (3) systematically classifying and recycling the dephosphorized slag and decarbonized slag of the converter produced by the conventional converter, sorting and ventilating and drying. And then respectively mixing the dried converter dephosphorization slag and decarburization slag with passivated calcium oxide powder according to the weight ratio of 1:1, uniformly mixing and grinding.
The length of the bottom blowing nozzle is 1.5 m, the bottom blowing nozzle is a stainless steel seamless pipe, and the size is 1400 mm.18mm.
The bottom blowing element according to the embodiment is applied to a 400 ton converter, 4 bottom blowing elements according to the embodiment are arranged at the bottom of the converter, and the maximum flow rate of argon or nitrogen blown by the bottom blowing element is controlled to be 0.07Nm 3 Blowing at/min/tThe maximum flow of dephosphorization slag powder and passivation calcium oxide powder is 1500kg/min, the maximum flow of blowing decarburization slag powder and passivation calcium oxide powder is 1500kg/min, the gas ratio of blowing powder is 30, and the inlet pressure of powder gas is 0.8-1.2 MPa.
The powder spraying operation control process comprises the following steps: first, the pressurization valve was opened, and the pressure in the pressurization tank was increased to 0.55MPa.
Charging period: nitrogen-blowing protection powder spraying element for charging scrap steel into converter and adding molten iron, and carrier gas flow rate is 0.5Nm 3 Per min/t, auxiliary blowing flow 0.5Nm 3 /min/t。
Deep dephosphorization period: the top-blown soft blowing mode is adopted, and the top-blown oxygen flow rate of the oxygen lance at the top of the converter is 3.5Nm 3 /min/t. Argon or nitrogen is blown for 30 seconds before blowing to protect the bottom blowing element, the gas flow is the same as the charging period, and the purpose is to protect the bottom blowing element and promote the temperature rise of molten iron in the furnace. Spraying composite slag powder after blowing for 30 seconds, wherein the powder spraying flow is 750kg/min, and the carrier gas flow is 0.04Nm 3 Per min/t, auxiliary blowing flow 0.1Nm 3 /min/t. And adjusting smelting time and powder spraying flow according to the temperature of the molten pool. The powder spraying flow is adjusted to 1500kg/min according to the temperature of the converter, and the carrier gas flow is 0.07Nm 3 Per min/t, auxiliary blowing flow 0.5Nm 3 /min/t。
Recovering dephosphorized slag: after the dephosphorization period is over, bottom blowing argon or nitrogen is used for protecting the bottom blowing element, dephosphorization slag is poured from a furnace mouth, the dephosphorization slag is recovered and separated, and the carrier gas flow is 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 And/min/t, and grinding for standby.
Deep decarbonization period: in the top-blown normal mode, the top-blown oxygen flow rate was in the range of 4.5Nm 3 /min/t. Switching powder spraying and blowing passivation calcium oxide powder, wherein the powder spraying flow is adjusted to 1500kg/min according to the temperature of the converter, and the carrier gas flow is 0.07Nm 3 Per min/t, auxiliary blowing flow 0.5Nm 3 /min/t。
And (3) in the later stage of smelting: the powder spraying amount is reduced to 500kg/min, and the carrier gas flow rate is 0.03Nm 3 Per min/t, auxiliary blowing flow 0.4Nm 3 /min/t. Stopping powder injection 1min before blowing, bottom blowing argon or nitrogen to protect the bottom blowing element, and determining tapping according to the final molten steel temperature and final carbon oxygen volume, final carbon content, final sulfur content, final phosphorus content, etcTime.
Recovering the decarbonization slag: after the decarburization period was completed, the bottom-blowing element was purged with argon or nitrogen at a carrier gas flow rate of 0.05Nm 3 Per min/t, the auxiliary blowing flow rate was 0.05Nm 3 Pouring the decarbonization slag from the furnace mouth, recovering, sorting and grinding for standby.
During tapping, argon or nitrogen is adopted to protect the bottom blowing element, and the auxiliary blowing flow is 0.05Nm 3 Per minute/t, the carrier gas flow rate was 0.05Nm 3 And (5) per minute/t, and finishing one smelting cycle.
The implementation results show that: after a 400 ton converter uses the converter bottom powder spraying technology of the invention, the final carbon-oxygen area is 5.0x10 -4 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.025 ]]0.006% end point phosphorus content [ P]The service life of the bottom blowing element is 4500 furnaces and is 0.002 percent.
Comparative example 1:
comparative examples were made under the conditions of example 2. In comparative example 1, a 100 ton converter was subjected to top blowing and bottom blowing under the same conditions, but no slag powder injection was performed, and only a passivated calcium oxide powder having a content of 100% was injected.
The implementation results show that: the 100 ton converter does not use the recovered slag powder for bottom powder spraying, only sprays the passivated calcium oxide powder, and the final carbon-oxygen area is 5.0 multiplied by 10 -3 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.045 ]]End point phosphorus content [ P ] of 0.016]0.020% and the service life of the bottom blowing element is 1500 furnace.
Comparative example 2:
comparative examples were made under the conditions of example 2. Comparative example 2 was a 100 ton converter, top and bottom blowing were performed under the same conditions, but no dusting was performed, and the recovered slag was added from the top only at each stage.
The implementation results show that: the 100 ton converter does not use the recovered slag powder for bottom powder spraying, and the final carbon-oxygen area is 9.0x10 -3 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.050 ]]End point phosphorus content [ P ] of 0.026 ]]0.033% and the service life of the bottom blowing element is 1400 furnace.
Comparative example 3:
comparative examples were made under the conditions of example 2. The comparative example 3 is a 100 ton converter, the two-stage recovery slag powder and the passivation calcium oxide powder are sprayed, and the powder spraying is not carried out according to parameters in the conditions, namely, the ratio of the spray dephosphorization slag powder to the passivation calcium oxide powder is 20:1, the maximum flow is 600kg/min, and the ratio of the blowing decarburized slag powder to the passivated calcium oxide powder is 20:1, the maximum flow rate is 600kg/min, and the gas ratio of the sprayed powder is 50.
The implementation results show that: the 100 ton converter does not use the bottom powder injection according to the limited required range, and the final carbon-oxygen area is 1.0x10 -2 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.056 ]]0.033% end point phosphorus content [ P]0.045% and the service life of the bottom blowing element is 1200.
Comparative example 4:
comparative examples were made under the conditions of example 2. Comparative example 4 is a 100 ton converter, and the injection double-period recovery slag powder and the passivation calcium oxide powder are not subjected to powder injection according to parameters in conditions, namely the ratio of the injection dephosphorization slag powder to the passivation calcium oxide powder is 10:1, the maximum flow is 600kg/min, and the ratio of the blowing decarburized slag powder to the passivated calcium oxide powder is 20:1, the maximum flow rate is 600kg/min, and the gas ratio of the sprayed powder is 50.
The implementation results show that: the 100 ton converter does not use the bottom powder injection according to the limited required range, and the final carbon-oxygen area is 1.0x10 -2 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.056 ]]0.033% end point phosphorus content [ P]0.042% and the service life of the bottom blowing element is 1200.
Comparative example 5:
comparative examples were made under the conditions of example 2. The comparative example 5 is a 100 ton converter, the two-stage recovery slag powder and the passivation calcium oxide powder are sprayed, and the powder spraying is not carried out according to parameters in the conditions, namely, the ratio of the spray dephosphorization slag powder to the passivation calcium oxide powder is 20:1, the maximum flow is 600kg/min, and the ratio of the blowing decarburized slag powder to the passivated calcium oxide powder is 10:1, the maximum flow rate is 600kg/min, and the gas ratio of the sprayed powder is 50.
The implementation results show that: the 100 ton converter does not use the bottom powder injection according to the limited required range, and the final carbon-oxygen area is 1.0x10 -2 Endpoint carbon content [ C]End point sulfur content [ S ] of 0.053 ]]0.033% end point phosphorus content [ P]0.045%, bottom blowing elementThe service life of the piece is 1200 furnaces.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that modifications and adaptations to those skilled in the art may be made without departing from the principles of the present invention, which are intended to be comprehended within the scope of the present invention.
Claims (9)
1. A method for preparing powder by recovering slag through double-stage smelting bottom injection of a converter is characterized by comprising the following steps:
recovering dephosphorized slag and decarburized slag of a converter, classifying to prepare powder, and respectively mixing the powder with passivated calcium oxide powder according to a certain weight ratio; the smelting deep dephosphorization stage adopts a top-blowing oxygen soft blowing mode, and the smelting deep decarburization stage adopts a top-blowing conventional mode; and (3) performing bottom blowing in the whole smelting period, taking argon or nitrogen as a carrier, and blowing mixed powder at the bottom of the converter (9) through a bottom blowing element (8).
2. The method for preparing powder by recycling slag through double-stage smelting bottom-spraying of a converter according to claim 1, wherein the mixed powder is dephosphorized slag powder and passivated calcium oxide powder in a deep dephosphorization stage, and is decarburized slag powder and passivated calcium oxide powder in a deep decarburization stage.
3. The method for preparing powder by using the recycled slag through double-stage smelting bottom spraying of the converter according to claim 2, wherein the mixed powder is specifically characterized in that the weight ratio of dephosphorization slag powder in the deep dephosphorization stage to passivation calcium oxide powder is [ 1-10 ]: 1-5 ], and the weight ratio of decarburization slag powder in the deep decarburization stage to passivation calcium oxide powder is [ 1-10 ]: 1-5.
4. A method for preparing powder by recovering slag from double-stage smelting bottom-injection of a converter as claimed in claim 2 or 3, wherein the injection speed v of the mixed powder of dephosphorized slag powder and passivated calcium oxide powder is as follows 1 Range 0<v 1 Less than or equal to 1500kg/min; the mixed powder injection speed v of the decarburized slag powder and the passivated calcium oxide powder 2 Range 0<v 2 Less than or equal to 1500kg/min; the particle size range of the mixed powder is 200-2000 meshes.
5. The method for pulverizing the recycled slag of the double-stage smelting bottom-injection converter of claim 4, wherein the flow rate of the argon or the nitrogen ranges from 0.02 Nm to 1.50Nm 3 /min/t; the flow range of the soft blowing mode in the deep dephosphorization period is 2.5-3.5 Nm 3 /min/t; the flow rate range of the deep decarburization period normal mode is 3.5-4.5 Nm 3 /min/t。
6. The method for preparing powder by recovering slag from bottom-blown gas of double-stage smelting of a converter according to claim 5, wherein the mass ratio of the mixed powder to the powder of the bottom-blown gas is 10.0-50.0.
7. The method for preparing powder by recycling bottom-injection slag in double-phase smelting of a converter according to any one of claims 1, 2, 3, 5 or 6, wherein the bottom injection is realized based on a device for preparing powder by recycling bottom-injection slag in double-phase smelting of a converter, and comprises a gas storage bottle (1), a gas tank (2), an oil-water separator (3), a feeding bin (5), a pressurizing powder injection tank (6), a blanking control valve (7), a bottom-injection element (8) and a converter (9); the inlets of the gas storage bottle (1), the gas tank (2) and the oil-water separator (3) are sequentially connected through a control valve; the outlet of the oil-water separator (3) is divided into a plurality of branches, a pressure gauge and a flowmeter (4) are arranged on each branch, and all the branches are connected to a pressurizing powder spraying tank (6); a feeding bin (5) is arranged above the pressurizing powder spraying tank (6); after the bottom end of the pressurizing powder spraying tank (6) is connected with the blanking control valve (7), the pressurizing powder spraying tank and the lowest branch are connected to the bottom end of the bottom blowing element (8), and the bottom blowing element (8) is connected with the bottom end of the converter (9).
8. The method for preparing powder by double-stage smelting bottom-injection recycled slag of a converter according to claim 7, characterized in that the bottom nozzles of the bottom blowing element (8) are arranged circumferentially, the diameter of the circumference being 1/2 of the diameter of the molten pool; the bottom nozzle is provided with two groups, and the included angle between each group is 30 degrees or 90 degrees.
9. Use of a converter double-stage smelting bottom-injection recycled slag pulverizing method in a converter steelmaking process, according to any one of claims 1-8, to obtain a terminal carbon-oxygen concentration, carbon content, phosphorus content and sulfur content.
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