CN101307375A - A kind of anti-sticking ladle slag modifier for refining outside the furnace - Google Patents

Abstract

The invention provides an anti-sticking ladle slag modifying agent for external refining, which consists of active lime, corundum slag and fluorite. The chemical compositions by weight percentage of the modifying agent are: 75 to 85 percent of CaO, 0 to 5.0 percent of SiO2, 2.0 to 8.0 percent of Al2O3, 4.0 to 8.0 percent of F<->, 0 to 5 percent of MgO, and the balance being impurities; in the impurities: FeO and MnO are less than 5.0 percent, H2O is less than 0.5 percent, and S and/or P is less than 0.08 percent. Compared with the prior art, the modifying agent has remarkable effect on relieving the slag sticking of ladles and RH submerged tubes, can effectively prevent the slag sticking of the ladles and the RH submerged tubes, improve the service life of the RH submerged tubes, and remarkably increase the effect of slag sticking prevention; the modifying agent does not increase the time of refining processing, contributes to the continuity of the production, and remarkably improves production efficiency. The charging quantity which does not stick slag can at least reach 12.

Description

A kind of anti-sticking ladle slag modifier for refining outside the furnace

technical field

The invention belongs to the field of steelmaking, and in particular relates to a refining ladle slag modifier used for preventing slag sticking to ladles and RH dipping pipes in the process of refining outside a furnace.

Background technique

During the refining process outside the molten steel furnace, due to the adhesion of high-temperature melt or the solidification and bonding after cooling, the ladle or RH dipping tube often has the problem of sticking steel or slag, which affects the normal production and the improvement of production efficiency. . For example, during the RH refining process, the sticky slag of the RH dipping tube will cause the RH dipping tube to become thicker and longer, and the ladle clearance will be reduced. It must be cleaned before it can be used. The dipping tube is damaged, and the vacuum chamber is offline in advance, which directly affects the improvement of production efficiency. Another example is ladle sticky slag and CAS refining impregnation cover sticky slag, which will directly affect production efficiency.

Aiming at the problem of slag sticking in the steelmaking field, the method of spraying high-temperature anti-sticking paint on the working wall of the equipment is mostly used at present to solve it. When it is exhausted, it needs to be sprayed again, otherwise the problem of sticky residue will appear again, which greatly affects the continuity of production and limits the improvement of production efficiency.

As disclosed in CN1429677A, a "calcium oxide coating for preventing sticky slag in steelmaking vessels" composed of limestone, slaked lime, _SiO2 micropowder, sodium tripolyphosphate, water glass, and paper fibers, and a kind of calcium oxide coating disclosed in _CN1068282 composed of _Al2O3 , Cr ₂ O ₃ , SiC, graphite and binder aluminum phosphate solution, sodium lignin sulfonate solution "anti-adhesive high-temperature coating for steel sticky slag" and Japanese patent 04-116117 discloses the use of 10-80% fluorite and 90% by mass fraction - 20% limestone as the main raw material for anti-stick coatings. The anti-stick coatings disclosed in the above-mentioned patents all have the problem that the coating will become thinner with the increase of service time. After a certain number of furnaces are processed, the coating will be consumed and lose its original effect, and it must be sprayed again, otherwise the anti-sticking coating will be damaged. The sticking effect is difficult to guarantee, that is, the method of using paint is less adaptable to continuous production. From the actual effect of production, the optimum number of furnaces for the paint disclosed in CN1429677A is 7 furnaces, while the number of furnaces for the paint disclosed in CN1068282 is 7-10 furnaces. This is far from meeting the requirements of production continuity, which greatly limits the improvement of production efficiency.

Contents of the invention

The purpose of the present invention is to provide a kind of anti-sticking ladle slag modifier for refining outside the furnace to prevent the ladle and RH dipping pipe from sticking to the slag. The service life of the RH dipping tube is conducive to the continuity of production and the improvement of production efficiency.

The purpose of the present invention is achieved in the following manner: a kind of anti-sticking ladle slag modifier for refining outside the furnace, characterized in that: the modifier is composed of active lime, corundum slag and fluorite, and the weight of the chemical composition of the modifier is The percentage meets: 75%<CaO<85%, 0%<SiO ₂ <5.0%, 2.0%<Al ₂ O ₃ <8.0%, 4.0%< ^F- <8.0%, 0%<MgO<5%, and the rest are Impurities, among which FeO+MnO<5.0%, H ₂ O<0.5%, S and/or P<0.08%.

Wherein, the percentage by weight of the chemical composition of raw material satisfies respectively:

Active lime: CaO>90%, MgO<8%;

Corundum slag: 5%<CaO<15%, 60%<Al ₂ O ₃ <80%;

Fluorite: CaF ₂ >85%, SiO ₂ <15%.

In addition, all raw materials are required to have moisture < 0.5%, S and/or P < 0.08%;

It is required that more than 90% of the crushed raw materials have a particle size of less than 8mm.

The effect of each chemical composition in modifier of the present invention is respectively:

CaO: forms low-melting point substances with raw slag, inhibits the precipitation of high-melting point phases, and is beneficial to reduce the melting point of slag;

CaF ₂ : Flux, accelerates the dissolution of CaO, and improves the fluidity of slag in a short time;

Al ₂ O ₃ : adjust the fluidity and crystallization properties of slag;

SiO ₂ : reduce the basicity of slag and adjust the high temperature physical properties of slag;

MgO: It belongs to the component brought in by raw materials, high content will reduce the fluidity of slag, and attention should be paid to the control of raw material composition;

FeO+MnO: It belongs to the impurities brought in by the raw materials. If the content is too high, it will increase the oxidation of the slag, which is not conducive to the refining process, and it is easy to form a high melting point phase;

H ₂ O, S and P: Impurities brought in by raw materials, in order to prevent them from polluting molten steel, the amount of them must be controlled. Among them, H ₂ O will increase [H] in molten steel, causing hydrogen embrittlement, white spots, etc., which will affect the quality of the product; S and/or P may cause molten steel to return to P and S, which will increase the brittleness of the product and affect its performance.

The particle size of the modifier is required to be less than 8mm, which is for the convenience of production.

Compared with the prior art, the anti-sticking ladle slag modifier of the present invention has the following characteristics:

1. CaO>75% in the modifier of the present invention belongs to high-CaO type slag, which is beneficial to form a low melting point phase with the components of refining ladle slag, and has a significant effect on reducing sticky slag in ladle and RH dipping pipe, and can improve RH The service life of the dipping tube and the effect of anti-sticking slag are significantly increased;

2. The modification agent of the present invention is added during refining preparation, without setting additional feeding stations and time, and without increasing the time of refining treatment, which is conducive to the continuity of production and significantly improves production efficiency;

3. The number of furnaces to maintain non-stick slag can reach at least 12 furnaces;

4. Controlling the content of H ₂ O, S and P in the modifier can ensure that the content of [H], [S] and [P] in molten steel will not increase due to the addition of modifiers, which will affect the quality of molten steel ; Control the particle size of the modifier to be less than 8mm, which is conducive to the rapid integration of the modifier into the slag, forming a uniform and stable ladle refining slag with a low melting point.

Detailed ways

The present invention will be further described below in conjunction with specific examples.

First, detect the ingredients of raw material active lime, corundum slag and fluorite, and select raw materials that meet the following weight ratio conditions, that is, active lime: CaO >90%; corundum slag: CaO 5-15%, Al ₂ O ₃ 60-80% ; Fluorite: CaF ₂ >85%, SiO ₂ <15%; moisture in the three raw materials <0.5%; S or/and P <0.08%; otherwise, it should not be used.

Then, dry, crush and sieve the above-mentioned raw materials, and it is required that more than 90% of the crushed raw materials have a particle size of less than 8mm;

In the third step, according to the conditions of the chemical composition of the anti-sticking ladle slag modifier, the weight of the required raw materials can be calculated, see Table 1.

The chemical composition (percentage by weight) of the anti-sticking ladle slag modifier of the present invention satisfies:

75%<CaO<85%, 0%<SiO ₂ <5.0%, 2.0%<Al ₂ O ₃ <8.0%, 4.0%< ^F- <8.0%, 0%<MgO<5%, the balance is impurities; Among the impurities, FeO+MnO<5.0%, H ₂ O<0.5%, S and/or P<0.08%.

Table 1 is the embodiment (percentage by weight) of formula of the present invention:

Table 2 is to meet the raw material formula (percentage by weight) of Table 1:

  Raw material and formula Recipe 1 Recipe 2 Recipe 3 Activated lime 70% 80% 85% Corundum slag 15% 5% 5% Fluorite 15% 15% 10% Effect ＞12 furnace non-stick ＞12 furnace non-stick ＞12 furnace non-stick

The preparation method of the anti-sticking ladle slag modifier for refining outside the furnace of the present invention comprises the following steps:

1. Detect the chemical composition of raw material active lime, corundum slag and fluorite;

2. Dry, crush and sieve the above raw materials respectively, and it is required that more than 90% of the crushed raw materials have a particle size of less than 8mm;

3. According to the conditions of the weight percentage of the chemical composition of the anti-sticking ladle slag modifier, that is, 75%<CaO<85%, 0%<SiO ₂ <5.0%, 2.0%<Al ₂ O ₃ <8.0%, 4.0%< F ^- <8.0%, 0%<MgO<5%; the balance is impurities, wherein FeO+MnO<5.0%, H ₂ O<0.5%, S and/or P<0.08% in impurities. Calculate the weight of various raw materials required, and weigh them separately for use;

4. Mechanically stir and mix the above-mentioned raw materials weighed in proportion in a mixing mixer;

5. Carry out sealed and moisture-proof packaging.

The anti-sticking ladle slag modifier for refining outside the furnace of the present invention is added to the ladle before refining outside the furnace. When RH treated IF steel, the test was carried out in a 135-ton ladle, and the RH dipping tube could maintain no sticky slag for at least 12 furnaces.

Claims (5)

1. An anti-sticking ladle slag modifier for refining outside the furnace, characterized in that the modifier is composed of active lime, corundum slag and fluorite, and the weight percentage of the chemical composition of the modifier satisfies: 75%<CaO <85%, 0%<SiO ₂ <5.0%, 2.0%<Al ₂ O ₃ <8.0%, 4.0%<F-<8.0%, 0%<MgO<5%, and the balance is impurities. 2. The anti-sticking ladle slag modifier for external refining according to claim 1, wherein the chemical composition of the raw materials satisfies: Active lime: CaO>90%, MgO<8%; Corundum slag: 5%<CaO<15%, 60%<Al ₂ O ₃ <80%; Fluorite: CaF ₂ >85%, SiO ₂ <15%. 3. The anti-sticking ladle slag modifier for refining outside the furnace according to claim 1 or 2, characterized in that the impurities in the active lime, corundum slag and fluorite are H ₂ O<0.5%, S And/or P<0.08%. 4. An anti-sticking ladle slag modifier for external refining according to claim 1 or 2, characterized in that the particle size of the activated lime, corundum slag and fluorite after crushing is less than 8mm. 5. The anti-sticking ladle slag modifier for out-of-furnace refining according to claim 1, characterized in that the anti-sticking ladle slag modifier is added to the ladle before the out-of-furnace refining, and the addition amount is 300-600Kg /furnace.