JPS5838483B2 - Method for suction removal of hot metal processing slag - Google Patents

Description

Detailed Description of the Invention This invention improves the fluidity of the slag generated during the deP, simultaneous deS, and deP treatment in the partial refining of hot metal, making it easier to remove the slag using a suction type slag or cleaner. The purpose is to

In recent years, instead of batch refining using a converter, a method of split refining of hot metal has been widely implemented.

The basic processing pattern is to first remove Si from the hot metal and then slag it, then remove P or simultaneously remove S, remove P and then slag, and then finish it by oxygen blowing.

The method of removing slag from hot metal and removing S and P at the same time is as follows:
This has already been proposed in Japanese Patent Application Laid-Open No. 55-94415.

The Si removal process basically involves supplying oxygen (vaporized or solid acid, or a combination of both) into the hot metal bath to remove Si in the hot metal.
This method removes the slag as O2, and the generated slag is SiO2.
It has a high content.

On the other hand, as the simultaneous de-S and de-P treatment, Ca O-Cao
The treatment is carried out by using a 12/KCl-based treatment agent and supplying oxygen (vaporized or solid acid, or a combination of both). Basicity (Cab/5in) of 3.5 or more, T
, it is desirable that the Fe content be 15 or less L.

On the other hand, in recent years, suction-type slag cleaners have appeared as a method for discharging slag after treatment, and this has made the slag removal work very streamlined.

However, the above-mentioned treated slag has a certain degree of basicity, but on the other hand, T.

Since it is desirable that the Fe content be lower, the slag after treatment has poor fluidity, and the suction type slag or cleaner does not discharge the slag smoothly and takes a long time, or the old scraping method is irrational. I had no choice but to use a method.

In view of the above points, this invention improves the fluidity of slag after P dephosphorization treatment or simultaneous desulfurization treatment, or slag after P deP treatment, making it possible to easily discharge slag using a suction type slag or cleaner. .

The contents of the present invention will be explained in detail below.

First, the treatment targeted by the present invention is a deP treatment performed sequentially after the deSi treatment of hot metal, or a simultaneous deS or deP treatment.

This is because in order to increase the dephosphorization efficiency in both treatments, it is desirable that the basicity of the treated slag is high (lower T, Fe, etc.).
This is because the fluidity of the slag after treatment is poor, and the purpose of this invention is to improve the fluidity of the slag.

Next, the present invention uses slag treated to remove Si as a slag fluidity improver.

As already mentioned, the Si removal treatment oxidizes the Si in the hot metal and converts it into S.
Si is removed as iO2, and Si in the generated slag
02 amount is very large.

Conventionally, some proposals have been made to reuse this Si-free slag & gas, for example, as raw material for blast furnaces, but in the present invention, we focus on the fact that the fluidity of slag improves when the basicity of slag is lowered. By adding this high SiO2-containing slag to the slag for deP treatment, simultaneous desulfurization, and slag for deP treatment and turning it into slag, the basicity of the slag is lowered and its fluidity is improved.

This is the first point of the invention.

In this case, it is preferable that the -J particle size is small and uniform for the Si-removed slag, and in order to obtain this, suction type slag,
It is sufficient to suck the Si-removed slag with a cleaner and then cool it with water.

The second point of the present invention is the addition of Si-free slag and the timing of slag formation.

As already mentioned, in the deP treatment or simultaneous de-S and de-P treatment, the basicity in the treated slag is preferably high to some extent in order to improve the efficiency of de-P.

However, if a Si-removal slag is added in the early to middle stages of treatment in order to increase the fluidity of the treated slag, the basicity of the treatment slag decreases during the treatment, resulting in a decrease in P removal efficiency.

Therefore, in the present invention, in order to avoid such inconvenience, the Si-free slag is added at the time of shortage.

That is, it is added after one P-removal treatment, simultaneous S-removal, and P-removal treatment to form a slag.

2. It is added at the end of the P removal process, simultaneous deS, and the end of the P removal process to form a slag.

3. It is added at the end of the P-removal process, simultaneous S-removal, and from the end of the P-removal process to after the end of the process to form a slag.

In cases 2 and 3 above, the end of processing is 3 years from the end of processing.
~5 minutes or more is preferred.

In this way, by adding Si-free slag and turning it into slag after the P-removal treatment, simultaneous S-removal, and P-removal treatment are completed or completed,
There is no concern that the processing efficiency will decrease due to a decrease in the basicity of the treated slag (・.

Examples will be described below.

Example 1 (P removal treatment) 100 tons of hot metal with Si 0.55, SO, OIS, Po 115, and a temperature of 1340°C was placed in a processing vessel, iron ore was charged, gas was stirred, and oxygen was removed. Top-blown and processed for 15 minutes to form SiO, 15φ, 80.018
Po, No. 115 hot metal was obtained.

The slag produced after this Si removal process is manufactured by Kubota Iron Works.

The cleaner sucked it out from the top and turned it into a water slag.

The SiO2 content of the obtained Si-free slag was 45 da, and the particle size was 2a or less.

After the Si removal treatment, without transferring the hot metal, CaO-based flux is added and impeller stirring is performed.
Further, the slag was dephosphorized by adding iron oxide and top-blowing oxygen for 15 minutes, and after the treatment was completed, 300 @ of the above-described desiliconized slag water slag was added to form a slag, and the basicity of the slag was 2.2.

Afterwards, this slag was suctioned out using a slag cleaner.

In addition, the Si content of the obtained hot metal was 0.01%, and the S content was 0.017%.
P was 0.015%.

FIG. 1 shows the suction and discharge efficiency of the Si-free slag in this example, and the suction and discharge efficiency of the P-free slag in the case where the Si-free slag is not added to the above example.

As is clear from this, according to the embodiment of the present invention, the discharge of slag was completed in a short time.

On the other hand, in the L/conventional method without adding Si-removal slag, hardening progressed as the surface temperature decreased, and only about 50 mm of slag could be removed.

Example 2 (simultaneous de-S, de-P) De-Si treatment was performed in the same manner as in Example 1, and without transferring the hot metal after slag, CaO-CaCl2-based flux was added, stirring was carried out using an impeller, and iron oxide was added. , and oxygen top-blowing for 20 minutes to remove S and P.

Three minutes before the end of the treatment, the above-mentioned Si-removed slag water slag was added to 500:7 to form a slag, and the basicity of the slag was 2.5 at the end of the treatment.

Afterwards, this slag was suctioned out using a slag cleaner.

In addition, the obtained hot metal components were Si0.01%, SO,00
The expected values were obtained at 9% and Po, 012%.

Simultaneous S removal in this example, suction and discharge efficiency of deP slag, and L-removal without adding deSi slag in the above example.
Figure 2 shows the simultaneous de-S and suction and discharge efficiency of de-P slag.

As is clear from this, according to this example, the slag discharge was completed in a short time.

On the other hand, in the conventional method without adding Si-removal slag, 30
Only about % could be removed.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are charts showing the slag suction and discharge efficiency when using the method of the present invention and when not using the method of the present invention.

Claims (1)

[Claims] 1 In split refining of hot metal in which hot metal is slaged after Si-removal treatment, followed by de-P treatment or simultaneous de-S, and slag after de-P treatment, the above-mentioned de-P treatment, simultaneous de-S, or final formation of the de-P treatment is performed. Alternatively, after the completion of the treatment, or from the end of the treatment to the end of the treatment, the above-mentioned Si-removed slag is added and turned into slag, and the fluidity of the above-mentioned deP or simultaneous de-S or de-P generated slag is increased, and then the same process is performed. A method for suctioning and removing hot metal slag, characterized by sucking and discharging the slag.