CN111334626A - Method for promoting TiN phase precipitation in high-purity molten iron outside blast furnace - Google Patents
Method for promoting TiN phase precipitation in high-purity molten iron outside blast furnace Download PDFInfo
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- CN111334626A CN111334626A CN202010185965.8A CN202010185965A CN111334626A CN 111334626 A CN111334626 A CN 111334626A CN 202010185965 A CN202010185965 A CN 202010185965A CN 111334626 A CN111334626 A CN 111334626A
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- molten iron
- nitrogen increasing
- nitrogen
- blast furnace
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B3/00—General features in the manufacture of pig-iron
- C21B3/02—General features in the manufacture of pig-iron by applying additives, e.g. fluxing agents
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Abstract
The invention provides a method for promoting TiN phase precipitation in high-purity molten iron outside a blast furnace, which relates to the technical field of blast furnace ironmaking and comprises the following steps: (1) uniformly placing a certain amount of nitrogen increasing agent at the bottom of the open type hot metal ladle; (2) the liquid high-purity molten iron smelted by the blast furnace flows along the molten iron runner and falls into the open molten iron tank to be fully mixed with the nitrogen increasing agent, so that the nitrogen increasing operation is completed; (3) and after the nitrogen increasing is finished, removing the nitrogen increasing slag by using a slag raking machine. The nitrogen increasing agent is simple in adding mode and operation, and the adding amount is flexibly, uniformly and accurately adjusted. The existing blast furnace production mode and flow are not changed, and the kinetic conditions are provided by the falling and flowing of the molten iron after the nitrogen increasing agent is added, so that the nitrogen increasing agent and the molten iron are fully mixed, the reaction is fully carried out, the yield of the nitrogen increasing agent is high, TiN phase in the molten iron is remarkably precipitated, and the industrial production adaptability is strong.
Description
Technical Field
The invention relates to the technical field of blast furnace ironmaking, in particular to a method for promoting TiN phase precipitation in high-purity molten iron outside a blast furnace.
Background
The high-purity molten iron is pig iron which is specially used for producing high-quality castings and has low contents of elements such as Ti, Mn, S, P and the like and few contents of specific trace elements. Most of China adopts a concentrate method to smelt high-purity pig iron. However, in recent years, the quality of high-purity pig iron is gradually reduced along with the continuous reduction of high-quality raw materials, wherein the standard exceeding of Ti element is the most typical. Therefore, reducing the Ti content in the high-purity pig iron becomes one of the important ways to improve the quality of the high-purity pig iron.
The [ Ti ] in the molten iron is a relatively active element and is easy to form a Ti (N, C) solid solution compound with C and N in the molten iron to precipitate. From the thermodynamic analysis, the carbon content of pig iron is close to saturation, and then the formation of Ti (N, C) solid solution in the molten iron is influenced by the combination of [ Ti ], [ N ] and temperature. When the content of Ti and the temperature of molten iron are fixed, the higher the content of N in the molten iron is, the more TiN is precipitated. At the interface of slag and iron in the blast furnace hearth, because of the covering of the slag layer, the molten iron does not directly contact with furnace gas, nitrogen in the furnace gas can only be dissolved in slag and then reaches the interface of the slag and iron through the slag layer, and the resistance of the mass transfer process is very large, so that the low content of the molten iron [ N ] becomes a restrictive link of TiN precipitation under the internal process conditions of the existing blast furnace.
Therefore, it is necessary to develop a method for promoting the precipitation of TiN phase in high purity molten iron in a blast furnace without changing the conventional production mode and flow of high purity pig iron, and to promote the precipitation of more TiN phase in the molten iron, thereby providing possibility for the subsequent removal of [ Ti ] from the molten iron.
Disclosure of Invention
Technical problem to be solved
Aiming at the defects of the prior art, the invention provides a method for promoting the precipitation of TiN phase in high-purity molten iron outside a blast furnace, aiming at promoting the [ Ti ] and [ N ] in the molten iron to be fully combined to precipitate more TiN phase.
(II) technical scheme
In order to achieve the purpose, the invention is realized by the following technical scheme:
a method for promoting TiN phase precipitation in high-purity molten iron outside a blast furnace comprises the following steps:
(1) taking a certain amount of nitrogen increasing agent, uniformly mixing, and placing at the bottom of an open type hot metal ladle;
(2) the liquid high-purity molten iron smelted by the blast furnace flows along the molten iron runner and falls into the open molten iron tank to be fully mixed with the nitrogen increasing agent, so that the nitrogen increasing operation is completed;
(3) and after the nitrogen increasing is finished, removing the nitrogen increasing slag by using a slag raking machine.
Further, the nitrogen increasing agent is a compound of nitrogen element and silicon element, and comprises the following chemical components in percentage by weight: 30% -40%, Si: 60 to 70 percent.
Further, the nitrogen increasing agent is powder with the density of 2.5-3.5 g/cm3。
Furthermore, the maximum particle size of the solid material of the nitrogen increasing agent is less than or equal to 2.0mm, and the particle size of less than 200 meshes accounts for 50-90%.
Further, the mass ratio of the nitrogen increasing agent to the molten iron is 0.1-1.0: 1000.
furthermore, the temperature of the molten iron is 1450-1530 ℃, and the temperature of the molten iron is reduced by 50-70 ℃ during the slag skimming period by adding the nitrogen increasing agent.
(III) advantageous effects
The invention provides a method for promoting TiN phase precipitation in high-purity molten iron outside a blast furnace, which has the following beneficial effects:
1. the nitrogen increasing agent is added at the bottom of the open type molten iron tank, and the open type molten iron tank belongs to a non-sealed container. Because the dosage of the nitrogen increasing agent is less, liquid molten iron flows into the open type hot metal ladle, the liquid level in the hot metal ladle is from bottom to top, dynamic conditions are provided by the falling of the molten iron and the flowing of the molten iron in the open type hot metal ladle, the reaction is fully carried out, stirring, blowing and other equipment are not required to be added, and the operation is simple.
2. The nitrogen increasing agent has the advantages of small consumption, no special requirements on molten iron components, good adaptability, no influence on the subsequent procedures due to the changes of molten iron temperature drop, components and the like, and small slagging-off amount.
3. The method has the advantages of simple adding mode and operation, accurate adding quantity and flexible adjustment. The existing blast furnace production mode and flow are not changed, the yield of the nitrogen increasing agent is high, TiN phases in the molten iron are obviously separated out, and the industrial production adaptability is strong.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 SEM image of molten iron sample before nitrogen addition in example 2;
FIG. 2 SEM image of molten iron sample before nitrogen addition in example 2;
FIG. 3 EDS chart of the iron melt sample before nitrogen addition in example 2;
FIG. 4 EDS chart of the iron melt sample before nitrogen addition in example 2;
FIG. 5 EDS chart of the iron ore sample before nitrogen addition in example 2;
FIG. 6 EDS chart of the iron ore sample before nitrogen addition in example 2;
FIG. 7 SEM image of a molten iron sample after nitrogen addition in example 2;
FIG. 8 SEM image of a molten iron sample after nitrogen addition in example 2;
FIG. 9 EDS chart of the iron melt sample after nitrogen addition in example 2;
FIG. 10 EDS chart of the iron melt sample after nitrogen addition in example 2;
FIG. 11 EDS chart of a molten iron sample after nitrogen addition in example 2;
FIG. 12 EDS picture of iron melt sample after nitrogen addition in example 2.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all 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.
Example 1:
in this embodiment, the molten iron is 410m3High purity pig iron conventional molten iron produced by blast furnace, N in molten iron]The content is 0.0040-0.0050%; the method for adding the nitrogen increasing agent into the molten iron in front of the blast furnace comprises the following steps:
and after tapping of the blast furnace, taking a molten iron sample before nitrogen increase without nitrogen increase in a molten iron ditch, and comparing the molten iron sample with the sample after nitrogen increase.
Preparing nitrogen increasing agent according to 0.3kg/t molten iron, wherein the nitrogen increasing agent is a compound of nitrogen element and silicon element, the chemical components and the content are that N is 38.0 percent, Si is 62.0 percent, and the density is 2.7g/cm3The maximum grain size is less than or equal to 1.7mm, and the grain size of less than 200 meshes accounts for 80 percent.
24kg of nitrogen increasing agent is evenly put at the bottom of the open type hot-metal ladle when the hot-metal ladle is about 80 t. Liquid high-purity molten iron smelted by the blast furnace flows along the molten iron runner and falls into the open molten iron tank, and the liquid level in the molten iron tank is from bottom to top, so that the nitrogen increasing agent and the molten iron are fully mixed, and the nitrogen increasing operation is completed. And (4) slagging off, namely taking a molten iron sample after nitrogen increase.
The test results of the iron melt samples before and after nitrogen increase show that [ N ] in the iron melt before nitrogen increase is 0.0045%, and [ N ] in the iron melt after nitrogen increase is 0.0078%, and the [ N ] is increased by 73.3%.
Example 2:
in this example, the molten iron is 142m3The invention discloses a method for adding a nitrogen increasing agent into high-purity pig iron conventional molten iron produced by a blast furnace, which comprises the following steps:
and after tapping of the blast furnace, taking a molten iron sample before nitrogen increase without nitrogen increase in a molten iron ditch, and comparing the molten iron sample with the sample after nitrogen increase.
Preparing nitrogen increasing agent according to 0.2kg/t molten iron, wherein the nitrogen increasing agent is a compound of nitrogen element and silicon element, the chemical components and the content are that N is 36.5 percent, Si is 63.5 percent, and the density is 2.9g/cm3The maximum grain size is less than or equal to 1.5mm, and the grain size of less than 200 meshes accounts for 75 percent.
About 60t of molten iron in one open type hot-metal ladle, 12kg of nitrogen increasing agent is evenly put at the bottom of the open type hot-metal ladle. Liquid high-purity molten iron smelted by the blast furnace flows along the molten iron runner and falls into the open molten iron tank, and the liquid level in the molten iron tank is from bottom to top, so that the nitrogen increasing agent and the molten iron are fully mixed, and the nitrogen increasing operation is completed. And (4) slagging off, namely taking a molten iron sample after nitrogen increase.
And cooling the molten iron sample before and after nitrogen increase to normal temperature, and observing the change condition of TiN phase in the pig iron by using a scanning electron microscope after sample preparation. As shown in figures 1-12 of the drawings.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (6)
1. A method for promoting TiN phase precipitation in high-purity molten iron outside a blast furnace is characterized by comprising the following steps:
(1) taking a certain amount of nitrogen increasing agent, uniformly mixing, and placing at the bottom of an open type hot metal ladle;
(2) the liquid high-purity molten iron smelted by the blast furnace flows along the molten iron runner and falls into the open molten iron tank to be fully mixed with the nitrogen increasing agent, so that the nitrogen increasing operation is completed;
(3) and after the nitrogen increasing is finished, removing the nitrogen increasing slag by using a slag raking machine.
2. The method for promoting the precipitation of TiN phases in the high-purity molten iron outside the blast furnace as claimed in claim 1, wherein the nitrogen increasing agent is a compound of nitrogen and silicon, and the chemical composition and content are N: 30% -40%, Si: 60 to 70 percent.
3. The method of claim 1 for promoting high purity molten iron outside of a blast furnaceThe TiN phase precipitation method is characterized in that the nitrogen increasing agent is powder, and the density is 2.5-3.5 g/cm3。
4. The method for promoting TiN phase precipitation outside the blast furnace as claimed in claim 1, wherein the maximum particle size of the solid material of the nitrogen increasing agent is not more than 2.0mm, and the particle size of less than 200 meshes accounts for 50-90%.
5. The method for promoting TiN phase precipitation out of the blast furnace according to claim 1, wherein the mass ratio of the nitrogen increasing agent to the molten iron is 0.1 to 1.0: 1000.
6. the method for promoting TiN phase precipitation out of the blast furnace according to claim 1, wherein the temperature of the molten iron is 1450 to 1530 ℃, and the temperature of the molten iron is reduced by 50 to 70 ℃ during the slagging-off period by adding the nitrogen increasing agent.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111809142A (en) * | 2020-07-21 | 2020-10-23 | 安徽工业大学 | Method for promoting generation and clustering of TiN in high-purity pig iron |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110616286A (en) * | 2019-10-31 | 2019-12-27 | 安徽工业大学 | Method for increasing nitrogen in molten iron in front of blast furnace smelting high-purity pig iron furnace |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110616286A (en) * | 2019-10-31 | 2019-12-27 | 安徽工业大学 | Method for increasing nitrogen in molten iron in front of blast furnace smelting high-purity pig iron furnace |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111809142A (en) * | 2020-07-21 | 2020-10-23 | 安徽工业大学 | Method for promoting generation and clustering of TiN in high-purity pig iron |
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Application publication date: 20200626 |