JPS63103018A - Converter blowing method - Google Patents

Abstract

PURPOSE:To inhibit the evaporation of an effective component in molten steel and to enhance the yield of the effective component by adding a liq. or solid coolant to the surface of the molten steel on which a jet of gaseous oxygen collides against the molten steel so as to drop the temp. of the molten steel. CONSTITUTION:A jet 15 of gaseous oxygen is blown on molten steel 14 in a converter 11 from an oxygen lance 12 to refine the molten steel 14. A liq. or solid coolant 16 is added to the surface 17 of the molten steel 14 on which the jet 15 collides against the molten steel 14. The temp. of the molten steel 14 is dropped by efficient cooling and the evaporation of an effective component from the molten steel 14 is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a converter blowing method, and particularly to a converter blowing method for reducing evaporation loss of active ingredients such as iron or manganese.

[Prior art 1] In converter blowing, the temperature of the collision surface (referred to as the lower boiling point) of the oxygen jet and molten steel in the decarburization region is 2200°C.
℃ or higher, which is 500℃ or more higher than the surrounding molten steel temperature, so the active ingredients such as iron and manganese in the molten steel will evaporate. This amount of evaporation is approximately 10 kg per ton of molten steel,
There are 0.1 to 2 tons of manganese per ton of molten steel, and the active ingredient is wasted in this filth.

In order to eliminate these drawbacks, conventional methods have been used to mix carbon dioxide gas with blowing oxygen to lower the temperature of molten steel and suppress the evaporation of active ingredients, or to mix slag components such as calcium oxide and magnesium oxide into molten steel. A method has been adopted in which the cover slag is added in advance before blowing to increase the cover slag, thereby suppressing the evaporation of the active ingredients.

[Problems to be solved by the invention] However, in the case of the method of blowing carbon dioxide gas to the fire point, a large amount of carbon dioxide gas is consumed and the cost is high, increasing the cost of converter blowing. There is a problem with this. In addition, in the case of the method of increasing cover slag, there is a problem that the amount of active ingredients that migrate into the slag and become oxides increases, and the yield of active ingredients such as iron and manganese decreases. be. In particular, when dephosphorizing hot metal is blown into a converter, manganese ore or chromium ore is introduced into the converter, but the amount of manganese and chromium distributed in the slag increases, resulting in a decrease in their yield. There is a problem with this.

This invention was made in view of such circumstances, and
It is an object of the present invention to provide a converter blowing method that reduces evaporation loss of active ingredients, maintains a high yield of active ingredients, and allows blowing with high efficiency and low cost.

[Means for Solving the Problems] The converter blowing method according to the present invention is characterized by adding a liquid or solid coolant to the collision surface between the oxygen gas jet and the molten steel during converter blowing. do.

[Operation 1] In this invention, the molten steel is blown by blowing an oxygen gas jet onto the molten steel. In this case, a liquid or solid coolant is added to the collision surface between the oxygen gas jet and the molten steel. This lowers the temperature of the molten steel and suppresses evaporation of the active ingredients from the molten steel. In this case, since the coolant is liquid or solid, it can be cooled with high efficiency, and it is not necessary to add a large amount of slag, so the effective ingredient can be maintained at a high yield.

[Embodiments] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In converter blowing, the flash point temperature is as high as 2200°C, and the evaporation loss of active ingredients such as iron or manganese is large. Therefore, this evaporation loss is suppressed by lowering the temperature of the fire point.

In this embodiment, a liquid or solid coolant, such as water or raw dolomite, is added to the fire spot to reduce the temperature of the fire spot.

Addition of these materials to the fire point lowers the melt 14 temperature around the fire point due to the heat of decomposition of the calcium and magnesium carbonates in the water or dolomite.

In this way, by adding a liquid or solid coolant to lower the molten steel temperature at the fire point by 50 to 300°C, evaporation loss of iron, manganese, etc. can be effectively suppressed.

Next, the operation of this embodiment will be explained. First, an oxygen gas jet is sprayed onto the molten steel in the converter from an oxygen blowing lance inserted into the converter through an opening above the converter to oxygen blow the molten steel. In addition, while blowing an oxygen gas jet onto the molten steel, a liquid or solid coolant such as water or raw dolomite is continuously added to the boiling point until the middle stage of blowing. Then, due to the heat of decomposition of water or raw dolomite,
Removes the heat from the molten steel around the fire point and lowers the temperature of the molten steel to 50 to 300
℃ lower. In this case, since a liquid or solid is used as the coolant, the molten steel can be cooled with higher efficiency compared to gas. Also, since an inexpensive coolant such as water or dolomite is used, converter blowing is not possible. Does not increase costs. Furthermore, since there is no need to add many mountains of slag, there is little risk that the effective ingredients will be oxidized and the yield will decrease.

In this way, the amount of evaporation of the active ingredient can be reduced with high efficiency and low cost while maintaining a high yield of the active ingredient.

Next, a specific example of converter blowing based on this embodiment will be described with reference to the accompanying drawings.

Specific Example 1 FIG. 1 is a schematic diagram showing a first specific example of this embodiment. Reference numeral 11 in FIG. 1 is a 250-ton converter, in which molten steel 14 is stored.

An oxygen blowing lance 12 is inserted into the converter 11 through its upper opening, and an oxygen jet 15 is blown onto the molten steel 14 from the tip of the lance 12, causing a blowing reaction at the fire point 17. It looks like this.

The sub-lance 13 is arranged in parallel with the oxygen blowing lance 12, and supplies water 16 in a sprayed state to the hot spot 17 to lower the temperature of the molten steel 14 around the hot spot 17.

Next, the operation of this specific example will be explained. First, the oxygen jet 15 is blown onto the molten steel 14 from the tip of the lance 12 to blow the molten steel 14. Then, the time from the start of blowing to the end of blowing is expressed as a time rate, and the time from the beginning of blowing to the end of blowing is 70%, and water 13 is sprayed at the hot point 17. Spray in condition. In this case, the water supply amount is o, i to 1 ONm3/min.

Next, the effects of this specific example will be explained. Figure 3 is a graph showing the relationship between the blowing time rate and the amount of effective ingredient evaporation, with the horizontal axis representing the blowing time rate and the vertical axis representing the amount of evaporation of the active ingredient per minute. . In the figure, white circles indicate the case of converter blowing according to this specific example, and black circles indicate the case of converter blowing without adding a coolant. According to this, when no coolant is added, the amount of evaporation of the active ingredient is 2.0 to 0.5 KO/min in the blowing time rate of 0 to 70%, but in the case of this specific example, The amount of evaporation of the active ingredient is less than 0.5 kg per minute at the blowing time rate of O to 70%.

L12L FIG. 2 is a schematic diagram showing a second specific example of this embodiment. Components in the figure that are the same as those in FIG. 1 are given the same reference numerals and their explanations will be omitted. In the figure, reference numeral 18 denotes a guide member for guiding the raw dolomite and 19 introduced into the converter from a hopper (not shown), and is provided above the opening of the converter 11 with its tip facing the oxygen blowing lance 12. There is. Then, it falls along the oxygen blowing lance 12 and is supplied to the hot spot 17, thereby lowering the temperature of the molten steel 14 around the hot spot 17.

Next, the operation of this specific example will be explained. First, as in Example 1, melt! Blow 1114. Then, raw dolomite 19 is added to the hot point via the guide member 18 from the beginning of the blowing to the blowing time rate of 70%. In this case, the supply vehicle was set at 0.1 to 0.5 K (:I) per ton of molten steel per minute.As a result, the effect shown in FIG. 3 could be obtained as in Example 1.

In this embodiment, water or raw dolomite was used as the coolant, but the coolant is not limited thereto, and any coolant may be used as long as it can efficiently cool the coolant.

[Effects of the Invention] According to the present invention, since a liquid or solid is used as a coolant, molten steel can be cooled with high efficiency. Therefore, evaporation of the active ingredients in the molten steel can be suppressed without increasing the blowing cost.

Furthermore, since it is not necessary to use a large amount of slag, it is possible to maintain a high yield of the effective components and suppress evaporation of the effective components in the molten steel.

[Brief explanation of the drawing]

FIGS. 1 and 2 are schematic diagrams showing the actual application state of an embodiment of the present invention, and FIG. 3 is a graph diagram showing the effects of the present invention. 11; converter, 12.13: lance, 14; molten steel, 15;
Oxygen jet, 16; Water, 17; Fire point, 18; Guide member, 19; Raw dolomite. Applicant's agent Patent attorney Takehiko Suzue Figure 1

Claims (1)

[Claims] A converter blowing method characterized by adding a liquid or solid coolant to the collision surface between an oxygen gas jet and molten steel during converter blowing.