JPS5814484B2 - Kourosinodatsuriyuhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for discharging blast furnace slag discharged from a blast furnace in a slag gutter and a slag receiving pot.

In recent years, with the dramatic increase in steel production, the amount of blast furnace slag discharged has continued to increase, and currently in Japan, approximately 200 slags are emitted annually.
It has reached 1,000,000 tons.

However, the use of blast furnace slag is hidden behind steel products and is not very noticeable.Only a small portion is used as raw material for cement, and the majority is difficult to dispose of and is discarded in landfills in lowlands, the sea, etc. This is the actual situation.

Therefore, if a path to effective use of blast furnace slag is opened, it will not only solve the troublesome disposal problem, but will also be extremely important for the development of the steel industry as the development of an unused resource.

Was this invention invented to address these problems? The aim is to effectively utilize blast furnace slag as a desulfurization agent for hot metal.

Concerning the effective use of blast furnace slag as a desulfurization agent for hot metal, the present applicant has previously filed Japanese Patent Application No. 118549/1983 entitled "Continuous desulfurization method for hot metal".
．． It is proposed that a mixed desulfurization agent containing fluorite (2 or less) and fluorspar has sufficient desulfurization ability.

By the way, some researchers have conducted experimental studies on desulfurization of blast furnace slag, and it has been reported that vaporization desulfurization according to equation (1) occurs by blowing oxygen into molten blast furnace slag.

S”-+3/20=SO2+O-- ・・・・・・
(1) It is believed that the higher the oxygen partial pressure of the gas phase in contact with the slag and the higher the oxygen potential in the slag, the more the vaporization desulfurization is promoted.

As a result of various studies to desulfurize blast furnace slag on an industrial scale, the present inventors injected oxygen gas into the molten blast furnace slag to raise the oxygen potential of the slag and the gas phase in contact with the slag to a sufficiently high level. Considering that it is effective to maintain the slag, we added iron ore to the molten blast furnace slag discharged from the blast furnace during tapping, that is, the slag flow from the blast furnace to the slag receiving pot, while adding oxygen gas. It was confirmed that blowing into the air is extremely effective.

Considering the fluidity of the blast furnace slag, the amount of iron ore added at this time should be 1.6 to 2
．． It is necessary to add 0 wt%.

Further, in order to promote the reaction, fine particles are preferable, and a particle size of 5 degrees or less is desirable.

On the other hand, the oxygen gas to be blown needs to be supplied from the slag trough and the upper part of the slag receiving pot so that the amount of oxygen is sufficient to mix and contact the slag trough and the upper part of the slag receiving pan.

In this case, it is preferable to use a lance that is designed to mix well with the slag flow.

It is effective to use a conventional consumable lance or a water-cooled lance to make the slag flow and the oxygen flow oppose each other.

The drawing shows an embodiment of the present invention, in which slag 9 discharged from the slag outlet 2 of the blast furnace 1 is separated from hot metal from the skinmer 3, flows into the slag trough 4, and reaches the slag receiving ladle 6. The slag is fed at a constant speed by a belt conveyor 11 from the upper part of the slag trough 4 immediately after it is separated from the hot metal in the skimmer 3 and from the bottom of the slag trough 4 just before it flows into the slag receiving pot 6.

Oxygen gas is blown into the slag by a lance 7 placed on the slag gutter cover 5 and a lance 8 placed on the sludge receiving pan 6.

Both of these lances are expendable.

The lance 7 is installed countercurrently to mix the slag flow well, and the lance tip is in contact with the slag.

Similarly, the lance 8 is almost in contact with the slag and can be moved up and down as the level of the slag rises.

Examples of the present invention will be shown below.

Table 1 shows the composition (after treatment) of the blast furnace slag obtained as a result of the treatment under conditions of oxygen gas purity of 99.6% and treatment time of 150 minutes or more.

As described above, the present invention desulfurizes the blast furnace slag during blast furnace tapping, so the reaction efficiency of the supplied oxygen is high due to vigorous stirring and mixing, especially when the slag flows into the slag receiving pot. Therefore, the desulfurization reaction is efficiently promoted. The sulfur content in blast furnace slag can be stably reduced to 0.2% or less extremely efficiently, and the blast furnace slag can be effectively used as a desulfurization agent for hot metal.

Furthermore, the present invention has the advantage that it can be easily carried out with conventional equipment without interfering with the work during blast furnace tapping and without using special equipment, making it an extremely useful invention industrially. .

[Brief explanation of drawings]

The drawings are explanatory diagrams showing an example of an embodiment of the present invention. 1...Blast furnace, 2...Slag outlet, 3...
... skimmer, 4 ... slag, 5 ...
・Slag cover, 6... Slag receiving pot, 7... Slag cover part oxygen lance, 8... Slag receiving pot part oxygen lance, 9... Melting Blast furnace slag, 10...iron ore, 11...belt conveyor for adding iron ore.

Claims (1)

[Claims] 1 Blast furnace slag characterized by adding fine grained iron ore to the blast furnace slag discharged from the blast furnace in a molten state at a ratio of 1.0 to 2.0 wt% relative to the blast furnace slag to be treated and blowing gaseous oxygen into the blast furnace slag. Deflow method.