CN111893239B - Process for smelting high-phosphorus iron concentrate by combining direct reduction method with electric furnace double-slag method - Google Patents
Process for smelting high-phosphorus iron concentrate by combining direct reduction method with electric furnace double-slag method Download PDFInfo
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- CN111893239B CN111893239B CN202010906732.2A CN202010906732A CN111893239B CN 111893239 B CN111893239 B CN 111893239B CN 202010906732 A CN202010906732 A CN 202010906732A CN 111893239 B CN111893239 B CN 111893239B
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- 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
- C21C5/52—Manufacture of steel in electric furnaces
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/006—Starting from ores containing non ferrous metallic oxides
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- 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
Abstract
The invention discloses a process for smelting high-phosphorus iron concentrate by combining a direct reduction method with an electric furnace double-slag method. The method provided by the application takes high-phosphorus iron concentrate with P less than or equal to 0.3 percent and TFe more than or equal to 60 percent as a raw material, and directly obtains qualified molten steel by a direct reduction coupling electric furnace double-slag smelting technology. The unit technology and equipment involved in the method are easy to implement industrially, qualified molten steel can be obtained through scientific coupling of the system, the industrial application prospect is good, and the method has important significance for promoting the large-scale utilization of high-phosphorus ores.
Description
Technical Field
The invention relates to the technical field of metal smelting, in particular to a process for smelting high-phosphorus iron concentrate by combining a direct reduction method with an electric furnace double-slag method.
Background
The high-phosphorus iron ore is a characteristic resource in China, and the total reserve is about 100 hundred million tons. By adopting the traditional blast furnace ironmaking method, almost all P in the ore enters the molten iron, the content of P in the molten iron reaches more than 1 percent, and the traditional steelmaking method is difficult to smelt the molten iron with high P content. Although the high-phosphorus iron concentrate with P less than or equal to 0.3 percent and TFe more than or equal to 60 percent can be obtained after the conventional processes of wet grinding/fine grinding, acid leaching, magnetic separation and the like, the P in the molten iron still reaches more than 0.5 percent after the high-phosphorus iron concentrate is subjected to a blast furnace ironmaking process, and the converter still cannot economically smelt the molten iron with the P content of about 0.5 percent. The high-phosphorus iron ore which causes huge reserves in China is still a dead ore until now. Therefore, the development of the smelting technology of the high-phosphorus iron ore or the high-phosphorus iron ore concentrate is significant for the development of the steel industry in China and the resource safety of China.
Aiming at the comprehensive utilization of high phosphorus ore, more research works are made by predecessors. The available literature and patents show that all research works use high-phosphorus iron ore as raw material of iron-making process, and whether the research relates to direct reduction (gas-based or coal-based reduction), smelting reduction, or reduction and melting separation process ideas, the goal is to obtain qualified molten iron. However, all studies show that Fe/P separation under reducing conditions is extremely difficult. Under reducing conditions, as long as the temperature exceeds 1100 ℃, P will enter the iron phase at a very fast speed unless the slag-gold separation time is controlled within a very short time (such as 120 seconds). However, such short slag-to-gold separation times are difficult to achieve on an industrial scale, and therefore, high-phosphorus iron ore has not been applied to the steel industry so far.
Disclosure of Invention
Based on the above, the invention aims to provide a process for smelting high-phosphorus iron concentrate by combining a direct reduction method with an electric furnace double-slag method to obtain qualified molten steel. The invention takes high-phosphorus iron concentrate with P less than or equal to 0.3 percent and TFe more than or equal to 60 percent as a raw material, and directly obtains qualified molten steel by a direct reduction coupling electric furnace double-slag method smelting technology. The unit technology and equipment involved in the method are easy to implement industrially, qualified molten steel can be obtained through scientific coupling of the system, the industrial application prospect is good, and the method has important significance for promoting the large-scale utilization of high-phosphorus ores.
In order to achieve the purpose, the invention provides the following scheme:
a process for smelting high-phosphorus iron concentrate by combining a direct reduction method with an electric furnace double-slag method,
s1, reducing the high-phosphorus iron concentrate with the P content less than or equal to 0.3% and the TFe content more than or equal to 60% in a reducing atmosphere to obtain high-phosphorus DRI;
s2, adding the high-phosphorus DRI into an electric furnace, and adding 5-30% of scrap steel or common DRI;
s3, electrifying the electric furnace to heat up, discharging an oxygen lance to blow oxygen, blowing argon at the bottom, and adding a slagging agent to carry out deep dephosphorization;
s4, pulling out the dephosphorization residues after dephosphorization is finished;
s5, after slag is pulled out, the height of the oxygen lance is reduced, the oxygen blowing and bottom argon blowing strength is increased, and meanwhile, a slag former is added to realize deep decarburization;
s6, controlling the concentration and the temperature of the electric furnace end point C, P, tapping, and obtaining qualified molten steel, wherein the concentration of P in the molten steel is less than or equal to 0.03%.
Specifically, in some embodiments, the high-phosphorus iron concentrate of the present invention has the following composition:
TFe 60-63％，Al2O31-5％，SiO23-10％，CaO 4-9％，MgO 1-2％，MnO0.1-0.5％，P 0.1％-0.3% and the balance unavoidable impurities.
Specifically, in some embodiments, the reducing atmosphere described in step S1 is H2And CO. Preferably, H is in a reducing atmosphere as described in step S12And CO in a volume ratio of 1: 1-2.
Specifically, in some embodiments, soft oxygen blowing, bottom argon blowing, and mild stirring are used in step S3, and 5% -15% slag former is added.
Specifically, in some embodiments in steps S3 and S5, the slag former is one of lime and dolomite.
Specifically, in some embodiments, in step S3, the various slag formers are added in amounts to control the components of the dephosphorized slag to the following contents: r1.2-2.2, Al2O3％＝5％-15％、Na2O％＝0-2％、FeO％＝20％-40％。
Specifically, in some embodiments, more than 70% of the dephosphorized slag is removed in step S4.
Specifically, in some embodiments, strong oxygen blowing, strong argon bottom blowing stirring is used in step S5, and 3% -10% slag former is added.
Specifically, in some embodiments, in step S5, the various slag formers are added in amounts targeted to control the final slag composition to the following levels: 2.5-3.0% of R and Al2O3％＝5％-10％、Na2O％＝0-1％、FeO％＝15％-25％。
Compared with the prior art, the invention discloses the following technical effects: the method provided by the application takes high-phosphorus iron concentrate with P less than or equal to 0.2% and TFe more than or equal to 60% as a raw material, and qualified molten steel is directly obtained by a direct reduction coupling electric furnace double-slag smelting technology. The unit technology and equipment involved in the method are easy to implement industrially, qualified molten steel can be obtained through scientific coupling of the system, the industrial application prospect is good, and the method has important significance for promoting the large-scale utilization of high-phosphorus ores.
Drawings
FIG. 1 is a process flow diagram of the present invention;
FIG. 2 is a diagram showing the changes of [ C ] and [ P ] in molten steel in the smelting process of the present invention.
Detailed Description
The technical solutions of the present invention will be described clearly and completely with reference to specific embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a process for smelting high-phosphorus iron concentrate by combining a direct reduction method with an electric furnace double-slag method.
The present invention will be described in further detail with reference to specific embodiments in order to make the above objects, features and advantages more apparent and understandable.
Firstly, testing raw materials and steps
Tests were carried out based on the technical route of the present invention, using as raw material a high-phosphorus iron concentrate having the composition shown in table 1 below. Gas-based direct reduction, dephosphorization and decarburization are respectively realized in a silicon-molybdenum bar furnace and a 10kg induction furnace (with a top oxygen blowing device), and qualified molten steel is obtained.
Table 1 high phosphorus iron ore main component (%)
| TFe | Al2O3 | SiO2 | CaO | MgO | MnO | P | |
| Example 1 | 62％ | 3％ | 3％ | 4％ | 1％ | 0.2％ | 0.1％ |
| Example 2 | 63％ | 5％ | 10％ | 9％ | 2％ | 0.5％ | 0.2％ |
One of the test processes comprises the following steps:
1) the high phosphorus ore is put into a silicon-molybdenum rod furnace, the temperature is raised to 1000 ℃, H is pumped in2And reducing the mixed gas and CO at the volume ratio of 1:1 for 30 minutes, taking out the sample, cooling, and crushing to obtain the direct reduced iron. Repeating the direct reduction test for multiple times to obtain enough direct reduced iron raw materials required by the subsequent 10Kg of simulated electric furnace double-slag-method steelmaking;
2) respectively adding 10% of scrap steel into the direct reduced iron raw materials, and then adding the mixture into a 10kg induction furnace;
3) oxygen blowing is carried out by a lower oxygen lance in the induction furnace, and the distance between the oxygen lance and steel in two testsThe water surface is about 200mm-250mm, oxygen is blown softly, and the bottom is blown with weak argon for stirring. Simultaneously adding 12% of lime slagging agent, blowing oxygen for 15-20 min in the test, and then drawing out the dephosphorized slag, wherein the dephosphorized slag comprises the following components: r1.8, (Al)2O3％)＝6％、(Na2O％)＝1.0％、(FeO％)＝40％；
4) After the dephosphorized slag is pulled out, the oxygen lance is lowered to be about 100mm-150mm away from the steel surface, the oxygen flow is added at the same time, the argon bottom blowing strength is added, the deep decarburization operation is carried out, and 8% lime slagging agent is added at the same time. The components of the slag after decarburization are respectively as follows: r2.8, (Al)2O3％)＝10％、(Na2O％)＝1.0％、(FeO％)＝21％；
5) And (4) controlling the end points [ C ], [ P ] and the temperature in the induction furnace II, tapping, and obtaining qualified molten steel.
The second test procedure was substantially the same as the first test procedure, except that the amount of scrap added in step 2) was changed to 20%.
Second, test results
In the two test processes, the direct reduced iron, the initial molten metal after melting in the induction furnace, the molten metal after blowing oxygen and dephosphorizing in the early stage (before slagging off) and the end-point molten steel after deep decarburization in the later stage are respectively sampled and analyzed, and the whole processes [ C ] and [ P ] are changed as shown in the following figure 2. It can be seen that after direct reduction, P basically enters into metallic iron phase, more than 80% of P can be removed from metallic liquid phase by implementing oxygen blowing and reasonable slag component design in the early stage of the induction furnace, after the dephosphorization slag in the early stage is pulled out, the induction furnace is intensively decarburized in the later stage, and simultaneously further dephosphorized. Finally, qualified molten steel with the [ C ] lower than 0.01% and the [ P ] lower than 0.02% is obtained in both the two heats.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (5)
1. The process for smelting the high-phosphorus iron concentrate by combining the direct reduction method with the electric furnace double-slag method is characterized by comprising the following steps of:
s1, reducing the high-phosphorus iron concentrate with the P content less than or equal to 0.3% and the TFe content more than or equal to 60% in a reducing atmosphere to obtain high-phosphorus DRI;
s2, adding the high-phosphorus DRI into an electric furnace, and adding 5-30% of scrap steel or common DRI;
s3, electrifying the electric furnace to heat up, discharging an oxygen lance to blow oxygen, blowing argon at the bottom, and adding a slagging agent to carry out deep dephosphorization;
s4, pulling out the dephosphorization residues after dephosphorization is finished;
s5, after slag is pulled out, the height of the oxygen lance is reduced, the oxygen blowing and bottom argon blowing strength is increased, and meanwhile, a slag former is added to realize deep decarburization;
s6, controlling the concentration and the temperature of the electric furnace end point C, P, tapping to obtain qualified molten steel, wherein the concentration of P in the molten steel is less than or equal to 0.03%;
in the step S3, soft oxygen blowing and bottom argon blowing are adopted for weak stirring, and 5-15 wt% of slagging constituent is added;
in the step S3 and the step S5, the slagging agent is one of lime and dolomite;
in the step S3, the addition of various slag formers is based on controlling the components of the dephosphorized slag to reach the following contents: r1.2-2.2, Al2O3％＝5％-15％、Na2O％＝0-2％、FeO％＝20％-40％；
More than 70% of the dephosphorized slag is removed in the step S4;
in the step S5, strong oxygen blowing and strong argon bottom blowing are adopted for stirring, and 3-10% of slagging agent is added.
2. The process for smelting high-phosphorus iron concentrate by combining the direct reduction method with the electric furnace double slag method according to claim 1, wherein the high-phosphorus iron concentrate comprises the following components:
TFe 60-63％，Al2O31-5% of SiO 23-10%, 4-9% of CaO, 1-2% of MgO, 0.1-0.5% of MnO, 0.1-0.3% of P and the balance of inevitable impurities.
3. The process for smelting high-phosphorus iron ore concentrate by using the direct reduction method in combination with the electric furnace double slag method according to claim 1, wherein the reducing atmosphere in the step S1 is H2And CO.
4. The process for smelting high-phosphorus iron concentrate by using direct reduction combined with electric furnace double slag method according to claim 3, wherein H is contained in reducing atmosphere in step S12And CO in a volume ratio of 1: 1-2.
5. The process for smelting high-phosphorus iron concentrate by using the direct reduction method and the electric furnace double-slag method according to claim 1, wherein the addition amount of each slag former in the step S5 is controlled according to the following content: 2.5-3.0% of R and Al2O3％＝5％-10％、Na2O％＝0-1％、FeO％＝15％-25％。
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| SE517296C2 (en) * | 2000-02-17 | 2002-05-21 | Uddeholm Technology Ab | Method of manufacturing steel in arc furnace using granulated pig iron |
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| CN105755196A (en) * | 2016-03-30 | 2016-07-13 | 北京大学 | Clean and efficient steel metallurgy method |
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| SE517296C2 (en) * | 2000-02-17 | 2002-05-21 | Uddeholm Technology Ab | Method of manufacturing steel in arc furnace using granulated pig iron |
| CN101220413A (en) * | 2008-01-30 | 2008-07-16 | 郭长庆 | Technique for smelting ferroferrite with sponge iron |
| CN105755196A (en) * | 2016-03-30 | 2016-07-13 | 北京大学 | Clean and efficient steel metallurgy method |
| CN105838838A (en) * | 2016-04-18 | 2016-08-10 | 山西鑫立能源科技有限公司 | Method for preparing pure steel by coal gas direct reduction one-step method |
| CN106544461A (en) * | 2016-11-01 | 2017-03-29 | 武汉科技大学 | Based on the method that the high-phosphor oolitic hematite of Efco-Northrup furnace prepares conversion pig |
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