JPS58197252A - Method for refining fe-b-si alloy - Google Patents

Abstract

PURPOSE:To eliminate a stage for manufacturing an Fe-B alloy and to lower the manufacturing cost, by adding a boron compound to refined molten steel and by shifting boron into the molten steel by a reducing reaction. CONSTITUTION:Molten steel 3 obtd. by conventional melting with an electric furnace 1 is charged into a ladle refining furnace 2. An Fe-Si alloy 5 and coke 6 are added to the steel 3, and while heating the steel 3 with graphite electrodes 4, a boron compound 7 mixed with a flow of gaseous N2 is blown into the steel 3 through a lance 8 dipped in the steel 3. Boron is shifted into the steel 3 by a reducing reaction. B2O3, H3BO3, colemanite, borax, anhydrous borax or the like is used as the boron compound.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing 'e-B-3i alloy, which is an alloy for amorphous ribbons with excellent electromagnetic properties, which is cheaper than conventional melting methods and saves production energy. Regarding how it can be done.

Amorphous (non-crystalline) alloy is the conventional 6.5% 5i
The iron loss is extremely small compared to -Fe alloys, and significant energy savings can be expected by using it as a wound core material for ball transformers.

In addition, amorphous alloys can be made by ultra-quenching molten alloys.
Since a thin plate with a thickness of ~56 μm is directly manufactured, processes such as casting and hot rolling can be omitted, which has the advantage of reducing manufacturing energy costs.

This amorphous alloy contains Fe −'B −Si3
The alloy composition near the eutectic point of the elemental system is considered to be optimal, and this composition is Fe (80 to 85 at%)-B (10 to 15 atoms)-8i (2 to 6 atoms), and the weight% If converted to Fe-B (2,2,~3.3% by weight)
2 to 3.5% by weight).

The conventional method for producing Fe-B-Si alloys involves adding Fe-8i alloy and Fe-B alloy to low-carbon molten steel to obtain the amorphous alloy composition described above.

The Fe-B alloy used here is manufactured according to the following steps.

Boron (B) is sodium borate (SODIUM)
BORATE 0RE) (commonly known as Tincal (TIN)
CAL)), or calcium borate (CALCI)
UM BOR, ATE 0RE) (Perioborite (C
Boric acid (chemical formula H, BO,) is produced through a purification process and sulfuric acid treatment. In Japan, F containing around 20% by weight and 10% by weight of boron is produced by aluminum reduction of boric acid (thermite method) and carbon reduction (electric furnace method).
e-B alloy is produced.

As described above, manufacturing Fe-B alloys requires many steps and a large amount of energy, resulting in high costs, and the final product, the amorphous alloy, is also very expensive.

1 3 1 In the present invention, Fe-B-Si is added by adding Fe-B alloy.
In contrast to the above-mentioned conventional method of producing alloys, boron is directly added to molten steel in a compound state prior to boric acid and reduced, and the boron is transferred into molten steel, thereby producing Fe-B alloy. The aim is to omit the process and achieve significant energy savings.

The present inventors conducted extensive experiments using various addition methods to investigate the possibility of reducing boron compounds with Si in molten steel and transferring the boron (B) produced by the reduction into steel, and completed the present invention. I ended up doing it.

The principle of the Fe-B-8i alloy melt manufacturing method of the present invention is as follows.

Examples of boron compounds include B2O3, boric acid (H, BO,
χ Colemanite (2CaO・3B203・5H20),
Borax (Na, 0.2B20..10H20), anhydrous borax (Na, 0.2B, O,), etc. are used. One of these boron compounds is added to molten steel, and the boron compound is reduced by carbon and silicon in the steel to form an Fe-B-8i alloy.

B20. If we take this as an example and show it as a chemical reaction equation, it will be as follows.

2B, 0. +3Si=4B+3SiO,...
(1) B, 03+ 3C-2B+3CO (2) Silicon necessary for reduction is added to the steel in advance in the form of Fe-8i alloy or metallic silicon. Similarly, carbon is either carbonized with coke or the like, or added at the same time as the boron compound.

In order to establish the above process on an industrial scale,
It is necessary to make the boron transfer rate from the boron compound into the steel according to the above fl) and formula (2) close to well over 100. The inventors conducted experiments using various addition methods and obtained the following (
3) The optimal addition method was determined based on the boron yield defined by the formula.

Boron yield 3 (weight of boron transferred into steel) / (weight of boron contained in boron compound) x 100 (%)
... (3) Table 1 shows a comparison of the boron compound addition method and boron yield.

(4) Table 1 It is clear from Table 1 that the yield is highest when the boron compound powder is injected into the molten steel from the bottom tuyere of the reaction vessel, and when similarly injected from the immersion lance. Next to this.

Therefore, as a method for adding boron compounds, a method in which boron is injected as a powder from the bottom tuyere or immersion lance of a reaction vessel is superior in that boron is efficiently transferred into molten steel.

The amount of boron compound added by the method of the present invention is 1.25 to 2.0 times the required amount of boron because the yield is 50 to 80% even when the addition method is optimal. . Low-yield methods require 2.5 to 5 times more
Economically disadvantageous.

Silicon in steel reduces boron compounds, so the silicon concentration in steel (%Si) before adding boron compounds should be higher than the ultimately required target silicon concentration in steel [chi81''lf]. The target boron concentration in the Fe-B-3 heavy alloy is [B''If], and the silicon concentration in the steel before addition of the boron compound is [%Si].

Then, [%5t)o can be found by the following formula.

[Chi Si). ≧〔chiSi″l(+1.94 CchiB″I
f...(4) Here, 1.94 is a coefficient determined stoichiometrically from the reduction reaction equation of a boron compound (boric acid) with silicon.

The reaction vessel used in the present invention is suitably a bottom-blown converter or a ladle equipped with a heating device. The boron compound is preferably in powder form, and by blowing it into the molten steel together with a non-oxidizing or weakly oxidizing gas stream, the efficiency of the reaction can be increased and boron can be effectively transferred into the molten steel.

According to the present invention, instead of using an expensive Fe-B alloy, Fe-B-8 heavy alloy can be melted using a boron compound at a low cost. - It is no longer necessary to use B alloy.

Example 1 A 5-ton scale bottom-blowing converter was used to remove the slag after completing normal blowing to produce 300 yu of metal silicon and 30 yen of carbon (coke).
kp was added to the molten steel. Then boric acid (H, BO8)
300 kiloliters of nitrogen was mixed into the gas stream and blown into the molten steel through the bottom tuyeres of the furnace.

Table 2 shows changes in the composition of molten steel.

Table 2 Changes in the composition of molten steel (unit: weight%) In the case of this melting example, the boron concentration after boron injection is o, q64
Although the amount was less than the target 2.2-3.3%, the deficiency was made up by adding 130kg/Fe-B alloy (J) (boron purity 19%). . The amount of Fe-B alloy used is 2/3 of the conventional method.
Therefore, it is clear that it is economically advantageous.

Example 2 A Fe-B-8 heavy alloy was produced by the process shown in FIGS. 1(a), (b), and (C).

(a) Transfer molten steel 3 obtained by ordinary melting using electric furnace 1 to ladle refining furnace 2, (b) Add 90 kg of Fe-8 heavy alloy 5 to this molten steel 3.
/11 Carbon (coke) 6 was added at 8 kg/l, (C
) While heating the graphite electrode 4 with a lance 8 immersed in the molten steel, boric acid 7 was mixed into the N gas stream and 9/2 was blown into the total amount 200.

Table 3 shows changes in molten steel composition in this example. The target value for the final component was achieved, and the boron yield at this time was 78%.

(8) Table 3 Changes in molten steel composition (unit: weight%)

[Brief explanation of drawings]

FIGS. 1(a), 1(b), and 1(C) are process diagrams of an embodiment of the present invention using a ladle refining apparatus. 1... Electric furnace 2... Ladle refining furnace 3... Molten steel 4... Electrode 5... Fe-8i alloy 6... Carbon (coke) 7... Boric acid 8... Lance ,' (11) 1st (a) (b) Mu (C)

Claims (1)

[Claims] A method for melting an IFe-B-8i alloy,
A method for producing an Fe-B-8i alloy, which comprises adding a boron compound to previously produced molten steel and transferring boron into the molten steel through a reduction reaction. 2. After decarburizing the molten steel using a bottom blowing converter and raising the temperature, a boron compound is blown into the molten steel through the bottom tuyere along with a non-oxidizing or weakly oxidizing gas stream, and the boron compound added in advance to the molten steel is reducing the boron compound with silicon and carbon,
The Fe-B-Si alloy melting method according to claim 1, wherein boron is transferred into molten steel. 3 Fe-8 is added to the molten steel in a ladle refining device equipped with a heating device.
Fe-B-8 according to claim 1, wherein after adding the i-alloy and carbon, a boron compound is blown into the molten steel together with a non-oxidizing or weakly oxidizing gas stream while heating the molten steel.
i Alloy melting method.