JPS5932535B2 - Method for improving slag properties - Google Patents

Description

[Detailed description of the invention] The present invention relates to a method for improving the properties of slag.

Specifically, this relates to a method for increasing the crushability of slag and making it easier to handle when the slag solidifies.

Slag is inevitably generated due to metallurgy.

For example, in ironmaking and steelmaking, the ore reduction process in a blast furnace (
Blast furnace slag is generated from this, and converter slag is generated in the converter.

These slags are in a molten state at high temperatures, but solidify when the temperature drops.

Since the solidified slag has considerable strength, it takes a considerable amount of labor and time to crush the large lumps to a particle size that is easy to handle.

Furthermore, when the molten metal solidifies in the container, it becomes even more difficult to remove the portions that adhere to the walls.

It is of great practical value to make such slag easy to crush during solidification.

The present inventor conducted various studies to make slag easy to crush after solidification. It was possible to solve the problem by adding powdered mineral substances, which do not melt at the temperatures possessed by the metal, by blowing them into the interior of the molten metal with a carrier gas through a lance.

By this method, the slag has a high friability after solidification, and if it is carried out particularly well, the slag will have a CC/C ratio when solidified.
It has a /- to sand-like shape and can be crushed very easily.

Therefore, it is easy to handle such slag, and it can also be suitably used to recover useful substances, such as mixed metals, from the slag, or to post-process the slag to use it as a raw material for building materials.

The powdered mineral used in the present invention must have a specific gravity lower than that of the molten metal and must not melt at the temperature of the molten metal, and there are many minerals that satisfy these conditions, but among them, those that are easily available, Those with low precipitation are desirable, and metal oxides, metal hydroxides [arsenids, metal carbonates, etc.] are the most practical.

For example, metal oxides such as CaO, MgO, l'203,
5i02. Examples include Fe2O3.

These may be a mixture and do not need to be of particularly high purity.

For example, in the case of CaO, lump CaO produced in a lime furnace may be crushed.

CaO, which has a relatively small particle size and is called subsieve lime, may be used.

SiO□ may be diatomaceous earth.

Ca (OH) as a metal hydroxide 2. Mg(0
Examples of the metal carbonate include CaCO3, MgCOs, and dolomite.

In addition, any mineral that is easily available and has a specific gravity smaller than that of a molten metal and does not melt at the temperature of a molten metal can be used.

There is no particular limit to the particle size of the powdered mineral material, but the finer the particle size, the
The friability of slag has a large effect.

Particle size is 1w1. If it exceeds this, the amount of addition required to achieve the effect of achieving easy friability increases, resulting in disadvantages such as an increase in the amount of slag, a decrease in the temperature of the molten metal, and an increase in the cost of addition. Therefore, the particle size is preferably 1w1 or less.

The particle size referred to here is the average particle size, and the particle size distribution is within the normal range.

The amount added is determined depending on the properties and composition of the molten slag, the particle size of the mineral material, the desired friability, etc., but generally it is effective if it is 1 part by weight or more per 100 parts by weight of slag. ~30 parts by weight is preferred from the viewpoint of effectiveness and economy.

There is no upper limit to the amount added, but it will be determined automatically if economic efficiency is considered.

The method of adding minerals according to the present invention involves blowing powdered minerals into molten metal through a lance with a carrier gas, and uniformly dispersing the blown minerals on the contact surface between slag and molten metal. It is added to the slag by

In this case, it is desirable that the tip of the lance be located at the center of the molten metal at a depth of 1/2 or more, and the effect will be greater if the amount of carrier gas is large enough to prevent the molten metal or slag from being violently scattered.

Furthermore, in this method, it is effective to mix and inject other refining agents, and it is advantageous in terms of simplifying and simplifying the work.

Another feature of the present invention is to use a substance that generates or releases gas at the temperature of the molten metal among the powdered mineral substances mentioned above.

In other words, it was discovered that the effect could be achieved by injecting powdered minerals into the interior of molten metal (using carrier scum), and the amount of carrier gas should be large enough to avoid scattering of molten metal or slag. This is because the large amount of gas Q uniformly disperses the powdered minerals.

Therefore, this purpose can be achieved if the mineral substance itself to be added generates or releases gas, and even if the amount of gas generated is small, the scattering of molten metal or slag is slight, and moreover, the amount of gas in the slag is small. It was discovered that the dispersion of powdered mineral material into the material occurs uniformly.

A mineral that generates or desorbs gas means that the mineral itself generates or desorbs gas, or that it contains a substance that generates gas as one of its components.

Mineral substances themselves that generate or release scum include Ca(OH)2. Mg(OH)2.

Metal hydroxides such as Affl(OH)3, metal carbonates such as CaCO3゜MgCO3 dolomite are practically preferred, and gas-generating substances added to the mineral as a component include liquid or solid organic substances, e.g. Examples include heavy oil and plastic powder, and water is also effective.

These gas-generating substances and mineral substances may be simply mixed or may be chemically bonded.

The mixing ratio of the minerals is not particularly limited and is determined based on the amount of gas generated, the desired degree of friability of the slag, the processing time, etc., and may be 100% gas-generating minerals.

In addition, as mentioned above, it is of great practical value to combine powdered mineral materials with other refining agents and refining processes.

As a result of the present invention, the slag becomes easily fractured when solidified, and the ease of handling during slag treatment is much improved compared to the conventional method.In addition, the preferred shape greatly contributes to the effective use of slag. Therefore, the industrial value is extremely large.

The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

Examples 1-I to C, Comparative Example Mineral fine powder was blown into the center of hot metal with nitrogen gas through a lance.

The results are shown in Table 1. Powder/gas amount-I K9/50
NA Example 2-2 - Blast furnace slag is melted on top of hot metal, and powdered minerals consisting of or containing gas generating substances as shown in Table 2 are poured into the center of the hot metal using nitrogen gas through a lance in the same manner as in Example 1. Infused.

Liquid/gas amount = 1 pregnancy/ONn

Claims (1)

[Scope of Claims] 1. Powdered mineral material that has a specific gravity lower than that of the molten metal and does not melt at the temperature of the molten metal is added to the slag existing in a molten or semi-molten state on the upper surface of the molten metal. ,
A method for improving the properties of slag, characterized by adding the slag by blowing it into the interior of molten metal with a carrier gas through a lance. 2. Claim 1, in which the powdered mineral substance to be added is a mineral substance that generates or desorbs gas at the temperature of the molten metal, or a mineral substance that contains a substance that generates gas as one component. The described property improvement method.