CN111910048A

CN111910048A - Method for reducing slag adhesion of RH insertion tube

Info

Publication number: CN111910048A
Application number: CN202010843246.0A
Authority: CN
Inventors: 雷辉; 高鹏程; 黄登元
Original assignee: Pangang Group Panzhihua Steel and Vanadium Co Ltd
Current assignee: Pangang Group Panzhihua Steel and Vanadium Co Ltd
Priority date: 2020-08-20
Filing date: 2020-08-20
Publication date: 2020-11-10

Abstract

The invention discloses a method for reducing slag adhesion of an RH insertion tube, belongs to the technical field of metallurgy, and provides a method for effectively reducing slag adhesion of an RH insertion tube; can improve the service life of the RH inserting pipe and the continuous operation rate of RH. The invention effectively solves the problem of slag adhesion of the insertion tube by adding the modifier to modify the ladle slag; and by controlling the carbon content and oxygen content of the RH treatment; the service life of the insert pipe can be effectively prolonged, the average service life of the insert pipe is prolonged to more than 90 times, the average RH continuous treatment furnace number of the IF steel is increased by about 3.71 furnaces/time, the highest RH continuous treatment capacity is increased by more than 15 furnaces/time, the operation rate is greatly increased, and the production control level and the metallurgical effect are obviously improved.

Description

Method for reducing slag adhesion of RH insertion tube

Technical Field

The invention relates to the technical field of metallurgy, in particular to a method for reducing slag adhesion of an RH insertion tube.

Background

At present, in the RH vacuum treatment process, the insertion tube is stuck with slag to cause abnormal conditions such as large-range brick dropping of a lower opening, falling of castable and the like, and the service life of the RH insertion tube and the RH operation rate are seriously influenced; the continuous processing capacity of RH is restricted, the continuous production of the variety steel is severely restricted, the scale effect can not be fully exerted, and the continuity of production and the improvement of production efficiency are seriously influenced.

Disclosure of Invention

The invention solves the technical problem of providing a method which can effectively reduce slag adhesion of an RH insertion tube; can improve the service life of the RH inserting pipe and the continuous operation rate of RH.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for reducing slag adhesion of an RH insertion tube is characterized in that a modifier is added into ladle slag before RH treatment, and the ratio of the addition amount of the modifier to the mass of the corresponding furnace ladle slag is as follows: (0.02-0.1) to 1, wherein the modifier comprises the following components in percentage by mass:

CaO

SiO₂

MgO

F^-

FeO+MnO

Al₂O₃

H₂O

S

P

＞70

≤5

＜2

6～10

＜5

＜0.5

＜0.08

。

further, the method comprises the following steps: the method also comprises the following control steps: the mass content of carbon in the feed material before RH treatment is controlled to be 0.04-0.06 percent, and the mass content of oxygen is controlled to be 0.035-0.05 percent.

Further, the method comprises the following steps: the method also comprises the following control steps: controlling the mass content of oxygen in the discharged material after RH treatment to be 0.0008-0.0015%.

Further, the method comprises the following steps: carbon powder is added in the RH treatment process to adjust the mass content of the carbon to be 0.04-0.06 percent and the mass content of the oxygen to be 0.035-0.05 percent.

The invention has the beneficial effects that: the invention effectively solves the problem of slag adhesion of the insertion tube by adding the modifier to modify the ladle slag; and by controlling the carbon content and oxygen content of the RH treatment; the service life of the insert pipe can be effectively prolonged, the average service life of the insert pipe is prolonged to more than 90 times, the average RH continuous treatment furnace number of the IF steel is increased by about 3.71 furnaces/time, the highest RH continuous treatment capacity is increased by more than 15 furnaces/time, the operation rate is greatly increased, and the production control level and the metallurgical effect are obviously improved.

Drawings

FIG. 1 is a typical phase diagram of slag-bonding material;

FIG. 2 is an XRD spectrum of a slag adhering substance;

FIG. 3 is a schematic view of a 15-furnace continuous operation after modifier addition by the method of the present invention;

FIG. 4 is a schematic diagram of the prior method after 15 furnaces are continuously operated without adding a modifier;

FIG. 5 is an XRD spectrum of sample slag before a modifier is added in an LF procedure;

FIG. 6 is an XRD pattern of the test sample slag after the addition of modifier RH;

FIG. 7 is a back scattering electron enrichment image of sample slag when an LF procedure is in station;

FIG. 8 is a backscattered electron enriched image of sample slag after LF process outbound, and the sample slag is added with a modifier;

FIG. 9 is a backscattered electron enriched image of the sample slag when the RH process is out of the station.

Detailed Description

The invention is further described with reference to the following figures and detailed description.

The inventor analyzes the reason that the slag sticking of the insertion tube is large, the RH processing technology mainly produces pre-deoxidation steel types such as IF steel, and the like, and the slag sticking of the insertion tube is serious in the RH processing process due to the influence of factors such as large slag quantity, high oxygen activity and the like. The slag bonding substances at different parts of the insertion tube after RH treatment of steel are subjected to XRD (X-ray diffraction) analysis and mineral phase microstructure observation, and the phase composition and structure of the slag bonding substances are researched by using an SEM (scanning electron microscope) in combination with EDS (energy dispersive X-ray). As can be seen from fig. 1 and 2, the slag of the insert tube contains 10 to 25 μm of granular cold steel, and the main phases of the slag are magnesia-alumina spinel (MgO — Al2O3 is abbreviated as MA, and the same applies hereinafter) and MgO, and a small amount of dicalcium silicate (Ca2SiO4) is contained.

After the method is adopted, according to the actual field observation, the slag adhesion phenomenon does not basically occur in the first 5 furnaces in the process optimization test after the modifier is added, and the slag can smoothly flow down from the pipe wall. After 15 furnaces of RH refining continuous treatment, the insertion tube is found not to grow and become thick obviously, the use effect of the modifier is obvious, and the test achieves a very good slag adhesion prevention effect, which is shown in the attached figure 3 in detail; in contrast, the schematic diagram of the prior method after 15 furnaces are operated continuously without adding a modifier is shown in the attached figure 4.

In addition, referring to XRD patterns of sampled slag for different sequences of a typical IF steel heat as shown in FIGS. 5-6, wherein the LF sequence refers to refining and the RH sequence according to the present invention follows the LF sequence, the modifier of the present invention is added before RH treatment, preferably during LF treatment or immediately after LF treatment, wherein the ratio of the amount of modifier added to the mass of ladle slag for the corresponding furnace is: (0.02-0.1) to 1, can be specifically controlled according to actual conditions, and can be combined withAnd (3) adjusting and controlling the requirements on the mass content of carbon and the mass content of oxygen in the material before and after RH treatment. It was found that before the addition of the modifier, the slag phase contained a small amount of amorphous material, the crystalline portion of which was mainly composed of FeO and Ca₂SiO₄And CaO and Al₂O₃The complex composition of the composition, and in addition, a small amount of spinel phase may be present; as shown in fig. 5. After the modifier is added, the amorphous substances in the slag are obviously increased, and the crystal only has a small amount of Fe_0.9712O、FeF₂And SiO₂And the like. The analysis shows that after the modifier is added, no high-melting-point phase is separated out from the slag, and the amorphous substances are increased to a certain extent, so that after the modifier is added, the network structure of the complex oxide is destroyed, the melting point of the slag can be reduced, and the slag sticking condition of the insertion pipe can be reduced.

In order to further research the influence of the modifier on the structure of the molten slag, analysis is carried out; wherein FIGS. 7-9 show the chemical compositions of the phases in slag for different processes of a typical IF steel furnace, and Table 1 shows the chemical compositions of the phases in slag. It can be seen that before the modifier is added, namely data corresponding to the LF entering station, the phase of the condensed slag is mainly a solid solution of MgO + FeO, aluminosilicate and the like; after the modifier is added, namely data corresponding to LF outbound, a large amount of low-melting-point substance 11CaO 7Al appears in the slag₂O₃·CaF₂(ii) a After RH processing, i.e. RH outbound data, the slag still contains a large amount of 11CaO 7Al₂O₃·CaF₂Therefore, the slag sticking condition of the RH inserting pipe caused in the RH processing process can be effectively improved by adding the improver.

TABLE 1 chemical composition of slag phases

In addition, the present invention further includes the following control: controlling the mass content of carbon in the feed material before RH treatment to be 0.04-0.06% and the mass content of oxygen to be 0.035-0.05%; the control process is to control the feeding before RH treatment. The method can be specifically controlled in the LF treatment process, can be controlled by adding the modifier, and can also adopt corresponding conventional technical means in the prior art, such as controllable blowing time, addition of aluminum, carbon and other adjusting materials and the like. In addition, carbon powder can be added to adjust the mass content of carbon to be 0.04-0.06% and the mass content of oxygen to be 0.035-0.05% in the RH treatment process. In addition, the invention further requires to control the mass content of oxygen in the discharged material after RH treatment to be 0.0008-0.0015%, and the control requirement is also realized by carrying out corresponding control in the LF treatment process in the earlier stage.

The aim of the method is to further control and reduce Al reduction in slag by controlling the mass content of carbon and the mass content of oxygen₂O₃Thereby reducing the slag adhesion of the insertion tube.

Specific examples and comparative tables:

the optimization method provided by the invention is adopted for testing, the average number of continuous processing furnaces of 156 IF steel RH normal processing batches operated for 1530 furnaces is 9.81 furnaces/time, and is improved by 3.71 furnaces/time compared with 6.10 furnaces/time before testing when the optimization method provided by the invention is not adopted; the maximum continuous treatment furnace number can reach 15 furnaces/time and is far higher than 8 furnaces/time before optimization, the slag removal time of each time of the insertion pipe is reduced from average 2.5 h/time before optimization to less than or equal to 1.5 h/time after optimization, and the slag removal time is reduced by more than 1 h; the RH operation rate is greatly improved to 66.43 percent. The main measures taken before and after process optimization and the achieved effects are shown in table 2 below:

TABLE 2 comparison and Effect of the Main measures before and after optimization of the Process according to the invention

Procedure (ii)	Before optimization	After optimization
			Before RH treatment	Without adding material	Adding a modifier
RH inbound carbon control	0.03％～0.05％	0.04％～0.06％
			RH inbound oxygen control	0.05％～0.07％	0.035％～0.05％
RH outbound oxygen control	0.0012％～0.0025％	0.0008％～0.0015％
			Number of furnaces for RH continuous treatment	Average number of 6.1 times	Average 9.81 times
Number of continuous casting furnaces	≤8	10～15
			Insertion tube cleaning time	Average 2.5 hours	Average 1.5

Claims

1. A method for reducing slag adhesion of an RH insertion tube is characterized in that: adding a modifier into ladle slag before RH treatment, wherein the mass ratio of the addition of the modifier to the ladle slag of a corresponding furnace is as follows: (0.02-0.1) to 1, wherein the modifier comprises the following components in percentage by mass:

CaO SiO₂ MgO F^- FeO+MnO Al₂O₃ H₂O S P ＞70 ≤5 ＜2 6～10 ＜5 ＜5 ＜0.5 ＜0.08 ＜0.08

。

2. the method for reducing slag adhesion of an RH insertion tube as set forth in claim 1, wherein: the method also comprises the following control steps: the mass content of carbon in the feed material before RH treatment is controlled to be 0.04-0.06 percent, and the mass content of oxygen is controlled to be 0.035-0.05 percent.

3. A method of reducing slag sticking to an RH insertion tube according to claim 2, wherein: the method also comprises the following control steps: controlling the mass content of oxygen in the discharged material after RH treatment to be 0.0008-0.0015%.

4. A method of reducing slag sticking to an RH insertion tube according to any one of claims 1 to 3, wherein: carbon powder is added in the RH treatment process to adjust the mass content of the carbon to be 0.04-0.06 percent and the mass content of the oxygen to be 0.035-0.05 percent.