KR100328933B1 - Production method of slopping depressant against slopping inter converter - Google Patents

Abstract

PURPOSE: A method for manufacturing a slopping depressant by using wet dust generated from steelmaking process and pulverized coal dust generated from COREX is provided. CONSTITUTION: The slopping depressant is prepared by naturally drying a wet dust comprising T·Fe 70 to 80 wt.%, S 0.01 to 0.05 wt.%, CaO 6 to 10 wt.%, SiO2 5 to 8 wt.%, Zn 0.05 to 0.1 wt.%, MgO 2 to 6 wt.% and a balance of moisture in order to control its moisture content below 15 %; mixing (a) 60 to 85 wt.% of above wet dust, (b) 5 to 25 wt.% of pulverized coal dust comprising C 55 to 65 wt.%, S 0.4 to 0.8 wt.%, volatile portion 27 to 32 wt.%, CaO 6 to 8 wt.%, SiO2 1 to 3 wt.% and a balance of ash and (c) 10 wt.% of portland cement mainly comprised of CaO; and pelletizing the mixture in the form of pellet having a diameter of 2 to 10 mm by using rotary pelletizer.

Description

Production method of slopping depressant against slopping inter converter

The present invention relates to a method for producing a converter slope sedative to suppress the slipping generated during the converter blow in the steelmaking process, in particular wet dust and corex (corex) generated in the steelmaking process It is intended to manufacture a converter slope sedative that is mainly composed of anthracite fine powder and cement generated in the process.

In general, the purpose of converter refining in the steelmaking process is to manufacture molten steel by removing phosphorus (P) and carbon (C) components contained in molten iron within the target content, and the physical properties of slag are important to remove phosphorus from molten iron. .

That is, the physical properties of slag should be basic slag, and for this purpose, quicklime containing CaO as a main component during converter conversion is added at regular intervals during converter conversion, while fluorite is added to increase slag fluidity and converter refractory. Dolomite is added to the converter during the conversion of the converter to suppress the loss of solvent.

The molten iron from the blast furnace contains phosphorus (P) in an amount of about 0.1% by weight, and in the case of refining molten iron that has not been dephosphorized in the molten iron preliminary treatment in the converter process, such limestone and fluorite Since dolomite is added, slag of about 100Kg per ton of molten steel is generated in the converter after finishing converter converter.

In other words, the converter slag is composed of quicklime which is injected during converter conversion, SiO ₂ produced by oxidation of silicon (Si) in molten iron, and FeO generated by oxidation of iron in molten iron, and CaO of slag is about 40. It reaches -45 weight%.

In order to remove phosphorus effectively from converter refining, it is necessary to form basic slag, and generally, the weight ratio of CaO and SiO ₂ in slag is about 3.5 to 4.0.

In the converter refining, oxygen is sprayed on the molten iron at a supersonic speed to remove carbon and phosphorus, and carbon monoxide (CO) gas is generated by reacting the injected oxygen with carbon in the molten iron as shown in Equation (1).

Carbon monoxide produced by the reaction of Reaction formula (1) is particularly small in size of bubbles (foam), fine carbon monoxide is not easily released to the outside through the slag layer, stagnated in the upper portion of the molten iron and the slag layer to temporarily slag and molten iron It may cause a sudden upward upward phenomenon (hereinafter referred to as "slag forming"), or sometimes ejected out of the reaction vessel (hereinafter referred to as "sloping").

Sloping generated during the conversion of the converter not only leads to the loss of the valuable metal iron, but also very dangerous for the safety of operation, causing serious air pollution, the situation is very strictly regulated in recent years.

The present invention is to effectively and easily suppress the converter slope, while the experiment and analysis to recycle the anthracite fine powder produced in the wet dust and Corex process of the steelmaking process that had to be treated at a separate cost generated as a by-product in the conventional steel mill An object of the present invention is to provide a composition of the converter slope sedatives.

The present invention having the above object is 5 to 25% by weight of anthracite fine powder having a particle size of less than 0.5 mm and 10 parts by weight of Portland cement whose main component is CaO to wet dust generated in the steelmaking process. Add and mix by the amount of%, the size of the pellets prepared by mixing them is characterized in that the diameter of 2 to 10mm.

1 is a schematic diagram schematically showing a slope sedation effect according to the present invention.

2 is a schematic diagram of an X-ray fluorescence test apparatus.

Figure 3 is a photograph showing the forming behavior when the wet dust pellets do not contain anthracite fine powder.

Figure 4 is a graph showing the maximum slag reaching height and calm time of the present invention and the comparative material.

5 is a graph showing the amount of sedatives added to soothe slopes.

[Explanation of symbols on the main parts of the drawings]

One; Electric furnace 2; X-ray generator

3; X-ray camera 4; Camera adjuster

5; Monitor 6; Video recording device

The components of the wet dust used in the present invention are shown in Table 1 below, except for the moisture contained in the wet dust. Wet dust is obtained as a by-product from pretreatment refining, converter refining, and out-refining refining of steel making processes. In the past, such wet dust was used as a coolant during refining of converters at a separate cost.

division Total iron content (T, Fe) S CaO SiO ₂ Zn MgO Content (% by weight) 70-80 0.01 ~ 0.05 6.0-10.0 5.0 ~ 8.0 0.05-0.10 2.0-6.0

The anthracite fine powder produced in the Korex process is shown in Table 2 below, and has a particle size of less than 0.5 mm. In the present invention, anthracite fine powder having a particle size of 0.5 mm or more may be used, but such anthracite fine powder may be widely used in other industries without going through a processing process, and when used as a raw material of the present invention, an additional anthracite cost is paid. It has to be economically disadvantageous.

On the other hand, the anthracite fine powder generated in the Korex process has to invest a large amount of money to install a separate treatment facility, or at a separate cost, so the present invention can take anthracite fine powder generated in the Korex process at a very low price. It has advantages.

ingredient C S Volatility CaO SiO ₂ Anthracite powder 55-65 0.4 ~ 0.8 27-32 6 ~ 8 1 to 3

Table 2 shows the components of the anthracite fine powder used in the present invention, the content of anthracite fine powder in the present invention is 5 to 25% by weight. When the content of anthracite fine powder is less than 5% by weight, the amount of anthracite fine powder is relatively low, and thus, an inhibitory effect of the slope is relatively low, and a large amount must be added in order to obtain a slope inhibitory effect. On the other hand, when the content of anthracite fine powder is more than 25% by weight, the effect of calming the slope is not increased. When the content of the anthracite fine powder is relatively high, more oxygen must be blown from the converter to burn the anthracite coal. Conversion time of converter is increased, which is disadvantageous in consideration of converter productivity and economic efficiency.

Cement used in the present invention is a general portland cement (cement), the main component is CaO, the cement content is 10 to 15% by weight, the cement serves as a binder (binder, binder) of the mixture.

When the content of cement is less than 10% by weight, the strength of the invention is weak and easy to break during the transport process, and therefore, when used in the converter process, the amount of loss to the converter exhaust gas increases, which is disadvantageous. In addition, when the content of cement is more than 15% by weight, it is possible to produce high strength invention products, but the consumption of cement is relatively increased, which is economically disadvantageous, and the strength is increased more than necessary, thereby increasing the reactivity between the invention and slag. Since it inhibits, it is preferable to make cement content into 10 to 15 weight%.

The pellet size of this invention shall be 2-10 mm in diameter. If the diameter is 2mm or less, the amount lost by the converter exhaust gas is increased when the converter is blown, and if it is 10mm or more, the specific surface area is relatively reduced even if the same amount is injected, so the reaction efficiency with slag is lowered. Do.

The method of preparing the present invention's slope sedative by mixing the above wet dust, anthracite fine powder and cement is as follows.

First, the wet dust generated in the steelmaking process of the steel mill is transferred to the yard, and dried in the air until the moisture content of the wet dust reaches 15% by weight. If the moisture content in the wet dust exceeds 15% by weight, it is difficult to form spherical pellets.

An appropriate amount of anthracite fine powder and cement are added to the dried wet dust and mixed for 20 minutes in a mixer, which is then placed in a rotary pelletizer to form a spherical pellet having a diameter of 2 to 10 mm.

The prepared pellets are cured to have a water content of 10% by weight or less in the air.

If the content of water in the pellet exceeds 10% by weight, the proper pellet strength (more than 30kg / cm 2) cannot be obtained, so it breaks easily during the pellet conveying process. This is disadvantageous because the wits are lost to flue-gases.

The pellet produced by the above method can be easily used in the converter in a stable state.

When the present invention is added to the converter during blowing, the action of suppressing slapping of slag is as follows.

In general, the phenomenon of slag swelling together with gas during converter blasting is called "slag foaming" .Slag forming is a chemical reaction of oxygen and carbon in the molten iron to produce fine carbon monoxide bubbles, and fine carbon monoxide forms a slag layer. It is caused by not piercing and swelling with slag.

Such slag forming occurs more severely as the size of the carbon monoxide bubbles is smaller and the stability of the bubbles is higher. Therefore, the slag forming can be suppressed by changing the chemical properties of the carbon monoxide microbubbles or by applying a physical force to the microbubbles to grow the microbubbles into large bubbles to promote floating separation of the bubbles.

Anthracite fine powder in the present invention serves to coarse microbubbles of carbon monoxide. That is, since the anthracite fine powder has a very high non-wettability with slag, as illustrated in FIG. 1, carbon monoxide microbubbles are easily coalesced in the slag layer to form large bubbles.

The larger the bubble size attached to the anthracite fine powder, the greater the buoyancy applied to the bubbles, so that the coarse bubbles can easily exit the slag layer, thus reducing slag forming.

In addition, the anthracite fine powder generates carbon monoxide by chemical reaction with FeO in the slag, as shown in the following formula (2), and the carbon monoxide bubbles produced by the following formula (2) are already generated and carbon monoxide microbubbles that are attached to the anthracite fine powder surrounding It breaks down and coalesces into a large bubble to promote coarsening of fine carbon monoxide bubbles, and on the other hand, by reducing FeO in the slag, it increases the slag surface tension around the anthracite fine powder, making it difficult to generate fine carbon monoxide bubbles. In the following formula (2), [O] and [FeO] mean dissolved oxygen in molten steel and iron monoxide in slag, respectively.

When anthracite fine powder is injected into the converter alone during the conversion of the converter, the specific gravity of the anthracite fine powder is very light at 0.9g / cm3, so that the specific gravity does not penetrate into slag of 2.7-3.0g / cm3 and thus exists in the slag. Since it is difficult to collect and grow carbon monoxide microbubbles, it is difficult to obtain an effect of suppressing slag forming.

In the present invention, the anthracite fine powder is mixed with wet dust and cement generated in the steelmaking process to produce pellets having a specific gravity greater than slag of 3.5 to 4.0 g / cm 3. As it penetrates deeply into the slag layer, carbon monoxide can be discharged in the slag layer while penetrating the slag layer.

Therefore, when it is injected into the converter during the blow, it is possible to easily suppress the slag forming by the above-described action, it is possible to effectively prevent the slope.

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

In order to derive the content of anthracite fine powder in the present invention, the slag forming behavior according to the content of anthracite fine powder was analyzed using the X-ray fluorescence test apparatus of FIG. The experimental apparatus of FIG. 2 is manufactured to observe physical phenomena by chemical reaction at high temperature of 1300 ~ 1600 ° C. using X-rays.

The device consists of a high temperature furnace (1), an X-ray generator (2), an X-ray camera (3), a camera regulator (4), a monitor (5) and a video recording device (6). It has a structure capable of fluoroscopy and radiography.

In the present invention, in order to investigate the foaming behavior of the slag, first, a graphite crucible having an outer diameter of 55 mm, an inner diameter of 45 mm, and a length of 200 mm is prepared, and 200 g of molten iron, 40 g of converter slag, 20 g of blast furnace slag, and 2 g of fluorite are charged therein, and 1600 ° C. The contents were dissolved in argon atmosphere.

3 is a photograph of slag forming behavior generated when 5 g of sintered ore is added after dissolving the charge. When iron ore is added from FIG. 3, it can be seen that slag forming is greatly promoted.

This is because most Fe contained in the sintered ore is in the form of iron oxide, and when the sintered ore is added, the FeO content in the slag is increased, so that a large amount of fine bubbles are generated as the reaction with carbon in the molten iron increases.

Therefore, in the present experiment, the conventional slag sedative, iron ore and the present invention as shown in Table 3, respectively, were added for the purpose of calming the foaming after adding the charge of 5 g of sintered ore to the crucible after dissolving the charge to force slag forming. 5 g was added to measure the maximum height at which the slag reached and the time for the foaming to settle (hereinafter referred to as "treatment time") by slag forming.

Here, the calming time is defined as the time passing the point 2cm higher than the initial slag height as the slag reaches the maximum height while forming, and then lowered again.

In the present invention, the above experiment was repeated five times, and the average value of the maximum reaching height of the slag and the settling time was calculated and shown in FIG. 4. The weight% value of the horizontal axis of FIG. 4 means the weight% of anthracite fine powder.

division Wet dust Anthracite powder cement Remarks Conventional - - - Conventional calm material Comparative material 90 0 10 The invention 1 85 5 10 Inventive Materials 2 80 10 10 Inventive Goods 3 75 15 10 Inventive Goods 4 70 20 10 Inventive Materials 5 65 25 10 Comparative material 60 30 10 ironstone - - -

As shown in Figure 4 also when adding a conventional sedative, the maximum reaching height of the slag reaches about 8.4cm, the sedation time was 4.4 minutes.

In the case of pellets prepared using only wet dust and cement, that is, anthracite fine powder was not added, an extreme foaming phenomenon was observed in which the maximum reaching height exceeded the maximum height that could be measured in the experimental apparatus of FIG. It takes about 4.8 minutes to soothe it, and it can be seen that it is more disadvantageous than conventional sedatives in terms of slag forming sedative effect.

In the case of the present invention, by adding the anthracite fine powder, the maximum reaching height of the slag reaches 8.0 ~ 9.0cm, it can be seen that the soothing effect is superior to the conventional sedative with a soothing time of 3.9 ~ 4.4 minutes.

In the case of the present invention from Figure 4, it can be seen that the maximum reach height is reduced and the soothing time is shortened as the content of anthracite fine powder increases.

On the other hand, in the case of the anthracite fine powder content of 30%, the maximum reach height is no longer reduced, it was found that the soothing time is no longer shortened.

In this case, the soothing effect is not improved, and in the converter, since more oxygen must be blown in order to sufficiently burn the added anthracite fine powder, sulfur (S) contained in the anthracite fine powder is molten steel as shown in Table 2 above. It is desirable to ensure that the content of anthracite fine powder does not exceed 25% by weight because it is incorporated into the molten steel to deteriorate the quality of molten steel.

When the iron ore is added, the maximum reaching height of the slag exceeds the maximum height that can be measured by the experimental apparatus and the calming time reaches 5.5 minutes, indicating that the suppression of slag forming is very disadvantageous. Therefore, when using the present invention, it was proved that the effect of suppressing slag foaming was very excellent, and when the above compositions were applied to the production industry, experiments were carried out at 300 ton converter to grasp the effect of suppressing slag slope. It demonstrates in detail in Example 2.

Example 2

The 300-ton converter at the steel mill was tested and when sloping occurs during the drilling, a sedative is added to calm the slope.

In this test, the conventional sedative material and the present invention were continuously added from the time when the slope occurred until the slope calmed down. In this test, a pellet prepared by adding 10% by weight of the anthracite fine powder of the present invention was used.

This is because, as can be seen in Figure 4, the soothing time of this adjustment exhibits soothing time similar to the composition of conventional soothing agents.

FIG. 5 shows 50 times of the above tests, and calculates the average value of the amount of sedatives charged in the first charge (hereinafter referred to as ch).

As can be seen in Figure 5 in the case of the present invention, the amount of sedatives added to calm down the slope is 750kg, it can be seen that about 40% less than 1250kg of conventional soothing agents.

This means that the amount of sedative for suppressing the slope is relatively small because the anti-slope effect of the present invention is superior to conventional materials.

The present invention as described above can easily obtain the effect of reducing the slope, and also has little economic feasibility, thereby reducing the waste cost by allowing the steelmaking process wet dust and the Corex process anthracite fine powder, which had to be disposed of at a separate cost, to be recycled. And it is effective to reduce environmental pollution.

Claims (1)

Wet dust generated in steelmaking process (T · Fe: 70 ~ 80% by weight, S: 0.01 ~ 0.05% by weight, CaO: 6 ~ 10% by weight, SiO _2: 5 ~ 8% by weight, Zn: 0.05 ~ 0.1% by weight , MgO: 2 to 6% by weight and the moisture as the residual amount) to naturally dry to 15% or less moisture, 60 to 85% by weight of the wet dust, powdered coal dust (C: 55 to 65% by weight, S: 0.4 to 0.8% by weight, volatile matter: 27 to 32% by weight, CaO: 6 to 8% by weight, SiO) ₂ : 1 to 3% by weight and ash as residual amount) 5 to 25% by weight and 10% by weight of Portland cement whose main component is CaO are mixed with a blender, A method for producing a converter slope sedative, characterized in that the pelletizing into a sphere to a diameter of 2 ~ 10mm by using a rotary pelletizer.

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