KR100340501B1 - A Method for Preventing Slopping Phenomina in Converter by Injection of Cokes and a Apparatus therefor - Google Patents

Abstract

PURPOSE: A method and apparatus for preventing slopping phenomena in converter by cokes injection are provided. CONSTITUTION: In a steel refinement by blowing oxygen into molten steel in converter, the method is characterized in that anthracite powder with a particle size of less than 1 mm is injected into the molten steel at an injection rate of 0.03 to 0.1 kg/t·molten steel·min at a point that slag foam is about to form during oxygen blowing, wherein the anthracite powder is injected into molten steel with being accompanied with inert gas at a supply pressure of 5 to 6 kgf/cm¬2 at a flow rate of 2.0 to 5.0 Nm¬3/min.

Description

A Method for Preventing Slopping Phenomina in Converter by Injection of Cokes and a Apparatus therefor}

The present invention relates to a method and an apparatus for preventing the slipping generated during converter blow in the steelmaking process, and more particularly, in the case of the slope during the converter blow, anthracite (coal) powder in the converter exit And a method for preventing the slope of converter slag by injecting a carrier gas and an apparatus used therein.

Basic slag should be formed in order to promote dephosphorization and desulfurization of the steel during the conversion of the converter, and a general method for forming the basic slag is the addition of quicklime whose main component is CaO during the conversion. In addition, fluorite is added to improve slag fluidity during slag conversion and increase the reactivity of slag, and dolomite may be used to protect the converter refractory. In the molten iron that is not dephosphorized in the molten iron pretreatment process, which is a preliminary process of the converter process, the molten iron contains about 0.1% by weight of phosphorus (P). At the end of refining, slag of about 100 kg per tonne of molten steel is generated, and CaO of slag reaches 40-45% by weight. In other words, the quicklime input during refining of the converter forms the main component of the converter slag together with SiO ₂ produced by oxidation of silicon (Si) in molten iron and FeO produced by iron. Formation of basic slag is essential to effectively remove phosphorus (P) from the converter, and the weight ratio of CaO to SiO ₂ is maintained at about 3.0-4.0.

On the other hand, in order to remove the carbon of the molten iron during the converter blasting to produce molten steel, pure oxygen is injected to the molten iron surface at a high speed, and the injected oxygen and carbon in the molten iron react to generate a large amount of carbon monoxide (CO) gas. Slag and molten iron are often ejected out of the converter due to the generation of CO gas, which is called slinging. Sloping wastes valuable metals and causes air pollution. .

Sloping in the converter is caused by the phenomenon of slag swelling by the CO gas produced from the reaction of carbon in molten steel with the injected oxygen, that is, slag foaming, and slag foam is the rate of carbon monoxide generation, It is influenced by the size of generated gas and the composition of slag. In other words, if the production rate of the gas produced by the reaction is fast enough, the physical properties of the slag itself exhibits a foaming phenomenon even if it is not advantageous to the foaming. On the other hand, if the properties of slag, ie slag viscosity, surface tension, presence of solid particles, presence of surface active elements, etc. are favorable for slag forming, a large amount of bubbles are formed even if the rate of foam generation is slow. .

Conventionally, when the slope is generated during converter blow, a slag sedative material is used to control this. The slag sedative material is produced by mixing the waste paper and converter slag in a predetermined ratio and drying in a rotary kiln, followed by extrusion molding. This sedative is cellulose (cellulous) is the main component and has the property of thermal decomposition at about 250 ℃. The gas released during the pyrolysis process forms a large bubble, which coalesces and agitates the surrounding small bubbles to suppress slag forming. However, this slag sedative is not sustained because it shows the effect of inhibiting slope only while the sedative is pyrolyzed, and has a problem of re-sloped after a certain time after the sedative is injected, and because the price is high. It is economically disadvantageous and has the drawback of greatly increasing the amount of converter slag.

The present invention has been proposed to solve the above problems, and an object of the present invention is to provide a method of effectively blowing the anthracite slag by blowing anthracite powder into the converter exit hole at high speed.

Another object of the present invention is to provide a converter slag anti-sloping device used in the above method.

1 is a configuration diagram of the anti-slope device of the present invention applied to the converter

Figure 2 is a graph showing the change in the amount of slag calming material used during the blowing according to the conventional and the present invention

The present invention for achieving the above object is a method of refining the steel by blowing oxygen in the molten steel of the converter, at the time of forming a foam (foam) in the slag during the oxygen drilling, using an inert gas as a carrier gas in the slag The present invention relates to a method for preventing converter slope by anthracite injection, wherein the anthracite powder is injected at a rate of 0.03-0.1kg / min per mol of steel.

In addition, the present invention is one side is inserted into the exit of the converter is attached to the supersonic nozzle for injecting anthracite powder by the carrier gas, the other side is connected to the supply pipe lance capable of horizontal movement by the transfer device; A gas supply device connected to a supply pipe of the lance to supply a carrier gas; A dispenser positioned between the lance and the gas supply device, connected to a supply pipe, and pressurizing a predetermined amount of anthracite powder; And a storage tank for supplying anthracite powder to the dispenser.

First, the anti-spopping device of the present invention will be described in detail with reference to the drawings.

As shown in FIG. 1, the anti-slope device of the present invention has a lance 6, a gas supply device 3 for supplying a carrier gas to the lance 6, and a dispenser for pressurizing and supplying a predetermined amount of anthracite powder. (2) and the storage tank (1).

The lance (6) is attached to the supersonic nozzle (5) on one side is configured to blow the anthracite powder and the carrier gas into the outlet 12 of the converter (8), the other side through the supply pipe 13 the gas supply device It is connected with (3). The lance can be horizontally moved by the transfer device 4. The supersonic nozzle 5 is preferably a nozzle having a laval shape capable of spraying a mixture of pulverized coal carrier gas at supersonic speed.

The gas supply device 3 is a device for supplying a carrier gas for transporting anthracite coal powder, and connected to a gas supply line on the outside.

The dispenser 2 is positioned between the lance 6 and the gas supply device 3 to be connected to the supply pipe 13, and the dispenser 2 is connected to the storage tank 1 through the transfer pipe 14. have.

Hereinafter, a method of preventing slipping of converter slag using the anti-slope device of the present invention will be described in detail.

First, when the slag forming phenomenon during oxygen blowing is recognized through the oxygen lance 7 in the molten steel 10 and the slag 9 in the converter 8, the lance moving device 4 is first moved as shown in FIG. The supersonic nozzle 5 is inserted into the tap hole 12. At the same time, the anthracite coal in the storage tank 1 is transferred to the dispenser 2, and then a pressure of about 6-7 kgf / cm 2 is applied to the dispenser internal pressure. At this time, the anthracite coal and the carrier gas is supplied to the supersonic lance 5 while being mixed in the supply pipe 13 due to the pressure difference between the dispenser and the carrier gas. The mixture of anthracite and carrier gas supplied to the lance forms a jet in the supersonic nozzle 5 and is injected into the slag 9 inside the converter 14.

The injected anthracite coal reacts in the slag (FeO) as in the following formula (1) to reduce (FeO). As the (FeO) in the slag is reduced, the surface tension of the slag increases, thus suppressing the formation of micro bubbles in the slag, thereby reducing the foaming phenomenon of the slag. In addition, the carbon monoxide generation phenomenon represented by Equation (1) below causes destruction of existing micro bubbles and promotes coalescence of micro bubbles when it occurs on the surface of micro bubbles that have already been generated, and thus has an effect of suppressing the occurrence of slaping due to foaming of slag. It is further expanded.

C (Anthracite) + (FeO) = Fe + CO (g)

At this time, the anthracite powder according to the present invention is preferably anthracite coal generated in the iron making process, the particle size of 1mm or less is appropriate.

If the particle size is 1 mm or more, the surface area of the anthracite coal is relatively reduced even when the same amount of anthracite is injected, thus reducing the effect of suppressing the slope because the reaction area of the anthracite coal is reduced. In addition, less than 1mm anthracite coal can be used only after disposal or separate processing process, and in general, since it is economically very disadvantageous to go through a separate processing process, raw materials can be easily obtained at low cost.

In addition, when supplying the carrier gas, the gas supply pressure is preferably injected in the range of 5.0-6.0kgf / ㎠. When the carrier gas supply pressure is less than 5.0 kgf / cm 2, when transferring the anthracite fine powder having a particle size of 1 mm or less, it is difficult to blow powder because of the pulsation phenomenon in which pipe clogging and puncture are repeated. In the above, the jetting phenomenon occurs in the transfer pipe, so that anthracite is almost never transported, so only gas is injected. At this time, it is preferable to use an inert gas such as nitrogen or argon as the carrier gas, and when using air or an oxidizing gas as the carrier gas, the gas includes a tap-resistant refractory body composed of magnesia (MgO) and carbon (C); It is very disadvantageous because it will react to damage the tap spout. And the flow volume of carrier gas is suitable for 2.0-5.0Nm <3> per minute. When the gas flow rate is 2 Nm 3 or less per minute, it is disadvantageous because it is difficult to inject anthracite fine powder having a particle size of 1 mm or less, and the jet formed is difficult to penetrate the slag layer, thereby reducing the effect of reducing the slope. In the case of 5 Nm 3 or more, the tap opening refractories are supercooled due to the carrier gas, and then when the tapping tap is taken out, the tap opening is in contact with the hot molten steel to overheat. It is disadvantageous because the tap is subjected to thermal shock due to such supercooling and overheating, which shortens the life of the tap refractory.

The jet formed through the supersonic nozzle during the converter blow acts to fundamentally prevent the formation of fine carbon monoxide bubbles that cause the sling by physically destroying and trapping the fine bubbles generated in the converter.

On the other hand, in the converter operation, large slitting occurs that causes severe environmental pollution about 3 to 4 minutes from the beginning of the blow operation, that is, from this time, by spraying anthracite fine powder by the above method, it is possible to effectively control the converter slope. do.

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

Example 1

Table 1 below shows the components of the anthracite sample used in the present invention, and the anthracite fine powder contains about 60% carbon and about 30% volatile matter as main components.

TABLE 1

At the 300 ton converter, the first slag forming phenomenon was recognized 3-4 minutes after the start of the blow. At this time, the lance moving device 4 is moved, the supersonic nozzle 5 is inserted into the tapping hole 12, the anthracite fine powder inside the storage tank 1 is transferred to the dispenser 2, and the dispenser internal pressure is reduced. It was adjusted to 6-7 kgf / cm 2. Accordingly, it was possible to visually observe that the anthracite fine powder and the carrier gas mixture were injected into the slag 9 while forming a jet through the lance. At this time, the injection time was maintained for 12 minutes from the time when the first slag forming was recognized.

In this experiment, the anti-slope effect during the blowing was investigated according to the injection rate of the anthracite fine powder, and the results are shown in Table 2 below.

TABLE 2

As can be seen in Table 2, when the input rate of the anthracite fine powder is 5kg or less per minute, a little slope occurs, when the injection of more than 10kg per minute, no slope occurs. As the input speed of the pulverized coal is increased, the slope can be more stably controlled. However, when the input speed is too large, additional oxygen is required for the reaction of the anthracite fine powder, and thus the blowing time becomes long, which is disadvantageous. That is, as shown in Table 1, the anthracite coal contains about 60% of carbon, and additional oxygen is required to burn it. For example, injecting 40 kg of anthracite coal per minute for 12 minutes, a total of 480 kg of anthracite coal is added, of which about 270 Nm3 of oxygen is needed to burn about 288 kg of carbon, which is about 60%. It will lead to a cost increase. In addition, when a large amount of fine powder is blown, the sulfur component of the anthracite coal enters the molten steel, which may act as a cause of degrading the quality of the molten steel. Therefore, in the case of a 300 ton converter, it is preferable to limit the injection speed of the anthracite fine powder during the drilling to 30 kg or less per minute, that is, 0.1 kg or less per minute per ton of molten steel, in consideration of the reduction of converter slope, the blowing time and the quality of the molten steel.

In the present experiment, nitrogen was used as a carrier gas when the anthracite fine powder was injected, and the gas flow rate was found to be 2.0-5.0 Nm 3 / min.

Example 2

When the refining operation of molten steel to prevent the slope in the 300 ton converter, the amount of use of the sedative material (anthracite coal) of the present invention and the conventional slag sedative material was compared, the results are shown in FIG. The result of the invention example in Figure 2 is the input (injection) rate of the anthracite powder 10kg per minute, nitrogen as the carrier gas 3Nm3 per minute, the time when the first occurrence of the slope was recognized, that is, 3 to 4 minutes from the start of the blow It is the result of adding anthracite fine powder for 12 minutes from, and also shows the result of 50 times experiments by the effect of adding anthracite fine powder during a blow.

As shown in FIG. 2, in the present invention, an average of 350 kg of sedative material (anthracite coal) was injected during the drilling to produce 300 tons of molten steel primary charge.

On the other hand, the results of the conventional example of FIG. 2 shows that whenever slope is detected during converter scavenging, a sedative is added through a hopper installed on the top of the converter, and an average value of the amount of sloping sedative is used for 2000 tons of 300 ton converters. Is the result of

As shown in Figure 2, in the case of the conventional example it can be seen that the dosage of the sedative reaches 1250kg. Therefore, when the present invention is applied to converter operation, the amount of sedatives can be greatly reduced.

The present invention effectively prevents slinging during converter scavenging, and recycles anthracite fine powder, a by-product of the Corex process, which is treated as a conventional waste, to reduce environmental pollution as well as to reduce the use amount of the sloping scavenger to greatly reduce the manufacturing cost of molten steel. There is.

Claims (2)

In the method of refining the steel by blowing oxygen to the molten steel of the converter, When foam is formed in the slag during the oxygen blowing, the particle size is 1mm by using an inert gas supplied as a carrier gas under the conditions of a flow rate of 2.0 to 5.0 Nm 3 / min and a supply pressure of 5 to 6 kgf / cm 2. An anthracite injection prevention method by anthracite coal injection, characterized in that the following anthracite powder is blown into the slag at a rate of 0.03 to 0.1 kg / min. The method of claim 1, wherein the time when the foam is formed in the slag is determined from 3 minutes to 4 minutes from the start of blowing blown anthracite powder characterized in that the blowing.

Images