JPS59128271A - Flow in material for molten iron desilicating launder - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention The present invention relates to refractories lined in containers for processing hot metal, such as blast furnace tap troughs, blast furnace pots, pig iron mixing cars, etc., and in particular provides slag resistance for desiliconization treatment of hot metal. This relates to pourable materials with excellent properties.

The desiliconization treatment of hot metal has begun to develop as a new technology in pig iron and steel production in recent years, and the conditions are so severe that conventional lining refractories cannot cope with it, and the conditions required for lining refractories are also extremely strict. There is something.

Desiliconization treatment usually uses Fe0 and mill scale or sintered ore mainly composed of Fe and Os as a desiliconization agent, and desiliconization of hot metal is carried out by the following reaction: Eli +2 Fe0-
+SiO, 10Fe Therefore, the refractory used is primarily required to have resistance to reaction with Fe0. Hereinafter, regarding pouring materials that are effective for the desiliconization treatment of hot metal according to the present invention, examples will be mainly described mainly for use in blast furnace tap channels.

Conventionally, blast furnace tap runners have been made using AJ, 03-8in2 aggregate as the main raw material, mixed with SiO and C, etc., for example, AJ, 0.20~gO wt%, 5iO~jO wt%. , BiC/θ~35% by weight, and C-~/θ weight% as main components.

However, SiO and O are mainly used as Fees contained in the desiliconizing agent (hereinafter referred to as desiliconizing agent) in the desiliconizing treatment of hot metal.
The refractory is oxidized by the following reactions, and the refractory is severely eroded, its structure deteriorates, and its durability is poor.

SiC+? Fe0-+,? Fe-1-Co-)-8i
O20+Fe0-+Fe-1-G.

As a countermeasure against such reactions, it is possible to use AJ, 03-8iO, and pouring materials that do not contain SiO, c, or B.

However, in this case, the main component Sin, , AJ□03
However, due to the following reasons, it is difficult to say that the durability is sufficient due to the reaction. 810 in poured material. reacts with FeO to produce 2ml'eO-8in, which is a low melting substance.

(F'ayalite, melting point/20!i°C),
eroded.

S10. -1-12FeO-+2F, eO-8iO.

Therefore, as a pouring material, S10. It is necessary to reduce the content of

On the other hand, AJ, O, is AJ, 0. -8in, if a large amount of desiliconizing slag or desiliconizing agent containing FeO as a main component enters into the system pouring material, the working temperature range of the pouring material (tazo ~ 1550℃) as shown in Figure 1. ), and the corrosion resistance is not sufficient as a pouring material for desiliconization.

As mentioned above, the conventional pouring material for FsO is AJ.
, O, -8in2 (-8iC-0) system is not sufficient.

In addition to these components, MgO is considered as a stable refractory to FeO. As is well known, MgO does not exist as a compound in reaction with 7eo, and forms a Mg0-FeO solid solution by absorbing FeO. In order to generate a liquid phase under actual usage conditions, especially in that temperature range, a Fe of more than qoqb is required as shown in Figure 1, and in actual furnaces, the amount of FeO is not as large as this.
Therefore, it can be said that this material is extremely stable compared to AJ, O, -8 inch, large-sized materials. In this way, Mg
O-based material can be said to be an effective material as a large-sized material for desiliconization, but its drawbacks are that when this material is used as a pouring material, workability is reduced due to elution of CaO from the MgO clinker, which is the main raw material, and water utilization of MgO is reduced. There are problems such as the occurrence of cracks due to the reaction. Also, since the thermal expansion properties of this material increase proportionally with the rise in temperature, cracks caused by thermal changes can cause damage when used in places where heating and cooling are intense, such as in blast furnace tap runners. This is a major factor.

Therefore, it is preferable to use the optimum amount of this material in combination with other components in order to take advantage of its effective properties.

As mentioned above, it was found that compositions containing MgO have corrosion resistance against FeO, and furthermore, compositions containing MgO-, AJ
, O, quality spinel was focused on. That is, for FeO,
This MgO-・AJ,O, has characteristics that make it difficult to react directly, so when a casting material using this spinel is actually used in a desiliconization treatment furnace, it is necessary to use a casting material with extremely excellent corrosion resistance. could be developed.

The product of the present invention contains 5% by weight of spinel, and the balance is Al2.
It is a pouring material that is mainly composed of O2 and has excellent corrosion resistance against desiliconizing agents for hot metal or desiliconizing slag.

The main mineral that makes up spinel, which is the main raw material, is M.
gO・AJ, 20. (spinel), and A 0. The main component is alumina, but it also contains MgO (periclase), etc., but as mentioned above, like the main cast material, water is used to facilitate workability, and a small amount of alumina is added. It has hardening properties due to the water use reaction with cement, but on the other hand, if MgO is the sole component among the contained components, a digestion phenomenon will occur due to the water use reaction of MgO, causing tissue damage. Since it can cause disintegration, there are restrictions on its content.

In the product of the present invention, the content of each component is MgO, l9~
30% by weight, AJ, 0.6 j - 75% by weight spinel is preferred.

The amount of spinel used in the product of the present invention is an appropriate amount by weight of kO-9, and if the amount used is less than the left θ weight, F
No effect on corrosion resistance against eO? ! If the weight is more than -1, the porosity in the structure of the poured material will increase and the strength will decrease, which is not preferable.

As the remaining refractory raw materials, sintered alumina, fused alumina, etc., which are aggregates, are mainly used, and alumina cement, which is a binder, is used. The appropriate amount of alumina cement is /-10% by weight; if the amount used is more than 10% by weight, the cao in the alumina cement becomes a flux and the corrosion resistance decreases, and if it is less than 1% by weight, it cannot be used as a pouring material. It is not possible to obtain sufficient strength. In addition to the above-mentioned spinel, alumina, and alumina cement, the casting material of the present invention also contains clay for imparting sinterability, which also contributes to fluidity and strength development, which are necessary characteristics as a casting material.
S10. In some cases, ultrafine powder is used. In this case, S
10. The content is preferably 5% by weight or less. 510
When 2 exceeds S weight %, corrosion resistance decreases.

In addition, small amounts of sodium phosphate as a deflocculant, borax as a hardening regulator, etc., which are commonly used in pouring materials, are added.

Examples of the products of the present invention will be described below.

Table 7 shows the particle size and blending ratio of the raw materials used in Example 1, as well as a comparison of corrosion resistance with Al2O and cast material as a comparative example. The formulation shown in Table 1 has a moisture content of 6~
7 weight - was added and kneaded for 3 minutes, 2JOX/
/FX45m + poured into metal frame, after construction, 10! The mixture was dried at ℃ for a period of time to obtain a cast material. Corrosion resistance is achieved by high frequency induction furnace method/! ; 10°C x 3 hours, 10% of pig iron as an erosive agent.
This is a comparative test using a mill scale of 2 kg.

Table-1゜* Spinel consisting of AJ, 0872% by weight and 0.2g% by weight of Mg.

As mentioned above, cast materials using spinel have superior corrosion resistance compared to conventional alumina-based cast materials.

Furthermore, the product of the present invention was poured into a blast furnace tap trough using a dedicated machine for desiliconization as a side wall lining refractory, and a comparison test with an alumina-based pouring material was conducted.

Figure 3 shows the damage rate index of the poured material by location in the desiliconization machine & when the alumina-based poured material (comparative example) at the location (A) immediately after the desiliconization agent is added is set to an index of 10θ. This is shown for comparison.

There is.

As shown in this figure, site A exhibits a remarkable reaction with the desiliconizing agent and FeO, which is the main component in the desiliconizing slag.

In B, compared to the alumina-based casting material, the spinel-based casting material has a lower damage rate and can be said to be an extremely stable casting material with respect to FeO. Site 0 is a site that is hardly affected by FeO, and there is no difference in damage between alumina and spinel systems, and both show small values.

These spinel-based pouring materials can be poured into the lining of conventional containers for desiliconizing hot metal, such as blast furnace pots, pig iron mixing cars, etc., or special containers for desiliconizing hot metal other than blast furnace tap runners. It can also be used as a cast material for lining.

[Brief explanation of the drawing]

Figure 1 shows the phase diagram of the AJ, 03-FeO system, Figure 2
The figure shows a state diagram of the Fe0-MgO system, and FIG. 3 is a diagram showing the damage rate index of the poured material by location in the desiliconization machine. In the figure, A: the area immediately after the desiliconizing agent is added, B: the area where desiliconizing slag is noticeable, and C: the position after the desiliconizing slag trough. Patent Applicant: Kobe Steel, Ltd. Shinagawa White Brick Co., Ltd. Shinagawa Rozai Co., Ltd.

Claims (1)

[Claims] A pouring material for desiliconizing hot metal, which is made of a refractory raw material containing 50 to 95% by weight of spinel with four main components of MgO, Ai, and 03, and the remainder being AJ, O, and the rest.