JPH10146656A - Flux for continuous casting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain flux excellent in the easiness of handling and dispersibility at the time of blending carbon powder. SOLUTION: The density ρ (g/cc) of the flux for continuous casting is 8.190×10<-3> D-3.824×10<-3> L+0.516 to 3.265×10<-3> D-3.334×10<-3> L+1.173. Wherein, the carbon powder pulverizing carbon black green compact shown with D(nm) for an arithmetic average grain diameter with an electron micro-scope of the carbon black and L(ml/100g) for DBP oil absorbing quantity, is contended.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a flux for continuous casting of steel.

[0002]

2. Description of the Related Art In continuous casting of steel, a base material such as calcium silicate is used to adjust a melting characteristic such as a softening point and a viscosity such as a fluoride and a carbonate, and a carbonaceous material such as carbon black and coke. Fluxes (steel making aids, mold powders) containing a melting rate regulator and the like are used.
This flux is injected into the molten steel surface in the mold and coats the molten steel surface. The role of this flux is to coat and melt the molten steel surface, block the air with the molten layer and the unmelted flux layer above it to prevent air oxidation of the molten steel. Prevents diffusion and keeps the molten surface warm; absorbs non-metallic inclusions in the molten steel that floats and separates; cleans the molten steel; between the mold and slab while the molten layer of flux covers the molten steel surface , And becomes a lubricant to improve the surface shape of the slab. In order to fulfill these functions, it is important that the melting behavior of the flux is appropriate. When carbon black is used as the carbon material of the melting rate modifier, the amount of carbon black is usually about 0.1 to 7% by weight in the flux.

[0003]

SUMMARY OF THE INVENTION Carbon black is
Usually, the bulk density immediately after production is as low as about 0.1 g / cc, and there are difficulties such as dusting during use and deteriorating the use environment. Therefore, granulated products called bead products are used, and the bulk density is 0.3 to 0.5 g / c.
c and a larger value than untreated carbon black. However, these are not sufficient in terms of the effect of suppressing dust generation during measurement and the effect of preventing dusting during transportation, and further have the disadvantage that the dispersibility at the time of blending is reduced, making it difficult to use. Therefore, the present inventors have conducted various studies in order to solve the above-mentioned problems, and found that the present invention can be achieved by using a specific carbon black molded body, and reached the present invention.

[0004]

That is, the gist of the present invention resides in a continuous casting flux containing carbon powder obtained by pulverizing the following carbon black compact. Density ρ
(G / cc): ρ = 8.190 × 10 ⁻³ D−3.824 × 10 ⁻³ L +
0.516 or more, ρ = 3.265 × 10 ⁻³ D−3.334 × 10 ⁻³ L +
1.173 or less (However, the arithmetic average particle diameter of carbon black by an electron microscope is D (nm), and the DBP oil absorption is L (ml / 100
g)).

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
First, the flux for continuous casting in the present invention contains a carbon powder obtained by pulverizing a specific carbon black compact. That is, the density ρ (g / cc) of the molded body is as follows: ρ = 8.190 × 10 ⁻³ D−3.824 × 10 ⁻³ L +
0.516 or more, ρ = 3.265 × 10 ⁻³ D−3.334 × 10 ⁻³ L +
1.173 It is a carbon black press-molded body represented by the following. More preferably, ρ = 8.686 × 10 ⁻³ D−4.031 × 10 ⁻³ L +
0.543 or more, ρ = 3.123 × 10 ^-3 D-3.189 × 10 ^-3 L +
1.122 or less An even more preferable range is as follows: ρ = 8.686 × 10 ⁻³ D−4.031 × 10 ⁻³ L +
0.543 or more, ρ = 3.123 × 10 ^-3 D-3.189 × 10 ^-3 L +
1.072 or less is preferable.

In each of the above formulas, D (nm) is the arithmetic average particle diameter, L (m
1/100 g) is the DBP oil absorption. Where DBP
The oil absorption is a value measured by a method based on JIS K6221-1982. The particle diameter of the carbon black is a value measured by the following method. The carbon black is put into chloroform and irradiated with ultrasonic waves of 200 KHz for 20 minutes to disperse, and then the dispersion sample is fixed to the supporting film. This is photographed with a transmission electron microscope, and the particle diameter is calculated from the diameter on the photograph and the magnification of the photograph. This operation is performed about 1500 times, and the values are obtained by arithmetic averaging.

[0007] The carbon black molded article of the present invention preferably has a powdering ratio of 40% or less, more preferably 20% or less. The powdering ratio can be determined by the following measurement method. A carbon black pressure molded body is precisely weighed to 25 ± 1 g (W), and is subjected to JIS K-622.
It is placed in a sieve having a diameter of 200 mm and an opening of 1 mm according to 1. A saucer and a lid are attached to this sieve, and JIS K-622
Shake for 20 seconds with a shaker according to 1. Remove the pan from the shaker, precisely weighed weight of the carbon black in the pan to 0.01 g, which was a weight after shaking (W _R), to calculate the powdering ratio by the following equation. Powdering rate _{(%) = (W R /} W) × 100 powdering rate by 40% or less, it is possible to prevent powdering due to an external force of vibration or friction applied to the molded body during transportation, handling property Especially excellent. Further, the ratio of the bulk density of the powdery or granular carbon black subjected to the pressure molding to the density of the carbon black molded body (hereinafter, also referred to as “bulk density ratio”) is 2.5 to 8 times. Preferably 3 to
It is good to make it 7 times. When the bulk density ratio is lower than 2.5, the handleability of the molded body tends to decrease.
On the other hand, when the bulk density ratio exceeds 8, the dispersibility tends to decrease.

[0008] The carbon black for obtaining such a pressure-molded article is not particularly limited, and carbon black produced by any method such as furnace black and acetylene black can be used. Further, those obtained by post-treating these various carbon blacks with various oxidizing agents and the like can also be used. These various carbon black powders and granules can be used without any particular limitation. The granules in this case may be granules obtained by ordinary wet granulation or dry granulation or flake carbon black obtained by using a roller compactor or the like.

In molding, a mold of any material may be used as long as it has a strength that can withstand the pressure applied during molding. For example, as a metal mold, SUS30
4, stainless steel mold such as SUS316, carbon steel mold,
Super steel such as tungsten carbide can be used. or,
As the resin mold, polytetrafluoroethylene (PTF
E), molds made of fluororesins such as poly (trifluoroethylene chloride) (PCTFE), polytetrafluoroethylene / propylene hexafluoride (FEP), plastics such as nylon, polyethylene, polycarbonate, phenolic resin, and composite materials FRP such as CFRP and GFRP, and alumina, zirconia, mullite and the like can be used as a ceramic mold. By making the mold used for molding slidable, pressure molding can be easily performed. The size of the mold is not limited, but practically, it is 1 cc or more, preferably 100 cc or more. If the amount is less than 1 cc, the transportation of carbon black becomes complicated. If necessary, a large molded body may be produced, cut into a suitable size, and transported and used as an aggregate. It is preferable that the volume of the obtained carbon black molded product is 1 cc or more, preferably 100 cc or more, because it is easy to handle.

[0010] The press used for pressurization includes a hydraulic mechanical press, a hydraulic hand press, a mechanical press,
Any press molding machine may be used as long as it can be press molded, such as an air cylinder press. The shape of the mold is also not particularly limited, and can be a columnar body having a triangular or other polygonal cross section, in particular, a cubic or rectangular parallelepiped molded body, according to a desired molded body shape, and is also preferable in terms of handling. It is. The carbon black is placed in the above-described mold and molded by pressing. The pressure during molding under pressure (molding pressure) is ^{2 to} 500 kgf / cm ² , preferably 5 to 400 kgf / cm ² . When the molding pressure is lower than ² kgf / cm ² , the powdering ratio tends to increase. On the other hand, when the molding pressure is higher than 500 kgf / cm ² , the dispersibility may not be sufficient with a commonly used disperser or the like.

In the present invention, the above-mentioned molded body is used after being powdered. The pulverization is preferably performed when the pressure-molded body is blended and mixed together with the other components constituting the flux, such as the base material and the melting property modifier. In this case, even when used in the size as it is taken out of the mold used for molding, the diameter of the mixer is 0.1 mm
What has been crushed to about 1 cm may be charged into a mixer.
Although there is no particular limitation on the crushing method, it is preferable to use, for example, a shear crusher such as a cutting mill, a rotary crusher, or a shear roll mill, since the density of the particles is not reduced during the crushing.

In the present invention, the other components to be compounded and the mixing ratio thereof can be determined by a conventional method. For example,
As a base material component, calcium silicate, slag, cement, wollastonite, etc .; silica powder, fly ash, etc. as powder property modifiers; fluorite, magnesium fluoride, magnesium carbonate as melting property modifiers such as softening point, viscosity, etc. And fluorides such as barium carbonate, carbonates and the like. Further, as the melting rate adjusting agent, those conventionally used such as coke powder can be used in combination with the carbon powder of the present invention. The mixing ratio of each of the above components is, for example, the base component 40
It is selected from about 15 to 30 parts by weight of a powder property modifier, about 20 to 25 parts by weight of a melting property regulator, and about 0.5 to 5 parts by weight of a melting rate regulator with respect to about 60 parts by weight. In the above blending and mixing, a Henschel mixer or the like usually used for mixing powders may be selected.

The flux of the present invention is easy to handle at the time of blending the carbon powder, and causes less contamination of the working environment. Furthermore, since it is excellent in dispersibility, even when the amount of carbon powder used is relatively small, it is possible to prevent contact between the base materials, to coat the base particles more uniformly, and to adjust the melting rate appropriately. It is suitable in terms of appropriate control.

[0014]

The present invention will be described in more detail with reference to the following examples. Example 1 37-ton 4-column single-acting hydraulic press (ram diameter 152.4)
mm (manufactured by Oji Machine Industry Co., Ltd.) and a SUS304 mold (inner method: 70 mm × 70 mm, height: 40 mm, manufactured by Mitsubishi Kasei Engineering Co., Ltd.). Press molded. The molding pressure was 18.0 kgf / cm ² . Particle size 30 nm DBP 113 ml / 100 g Bulk density 0.105 g / cc

2 parts by weight of the obtained carbon black pressure-molded product (density: 0.580 g / cc) was added to the following flux composition and mixed with a Henschel mixer to obtain a desired continuous casting flux. . The workability during work and the good work environment were significantly improved as compared with conventional bead products. Portland cement 50 parts by weight Fly ash 15 珪 Siliconite 12 マ グ ネ シ ウ ム Magnesium fluoride 15 ナ ト リ ウ ム Sodium carbonate 5 カ ー ボ ン Carbon black (press molded product) 3 鋼 Using this flux, a casting test of steel was performed. An extremely good flux effect was obtained in terms of reduction in the incidence of surface defects.

Claims (2)

[Claims] 1. A continuous casting flux comprising a carbon powder obtained by pulverizing the following carbon black compact. When the density ρ (g / cc) is ρ = 8.190 × 10 ⁻³ D−3.824 × 10 ⁻³ L +
0.516 or more, ρ = 3.265 × 10 ⁻³ D−3.334 × 10 ⁻³ L +
1.173 or less (However, the arithmetic average particle diameter of carbon black by an electron microscope is D (nm), and the DBP oil absorption is L (ml / 100
g)). 2. A pressure-molded article comprising carbon black of 2 to 2.
500kgf / cm ^Two2. A pressure-molding method.
For continuous casting.