KR20080110127A - Steel refinery flux composition of low temperature form using granulated slag - Google Patents

Abstract

In the temperature of the CaF2 and equivalent or less than, it is done by purpose to build up the melting point of the slag and can improve the mobility. A low temperature solvent formation for the steel manufacture refining using the quenched blast furnace slag contains calcium aluminate based minimill refining slag 60~84 weight, the metal aluminum 8~16 weight%, and the fly ash 4~16 weight% and quenched blast furnace slag 4~12 weight%, and performs the followings: a process where it transports the minimill refining slag generating during the minimill steelmaking process and the minimill refining slag separately cools; a process of smashing the cooled minimill refining slag to the size less than 50mm; a process of pulverizing the crushed minimill refining slag as described above to the size less than 3mm; a process of selecting to the minimill refining slag exceeding with 3mm; and a process of removing the ferric oxide from the minimill refining slag less than 3mm selected in the screening process.

Description

Steel refinery flux composition of low temperature form using granulated slag}

1 is a CaO-SiO ₂ -Al ₂ O ₃ state diagram.

2 is a CaO-Al ₂ O ₃ state diagram.

3A to 3B are graphs showing slag melting point and product melting point of the solvent compositions according to the present invention.

4a to 4b are graphs showing the dehydration rate and slag flowability of the solvent compositions according to the present invention.

The present invention relates to a steelmaking refining solvent, and more particularly, to a low-temperature type solvent composition for steelmaking refining using hand slag.

A steelmaking process is a manufacturing process which removes the impurity which exists in pig iron or scrap iron obtained after a steelmaking process, and obtains the high purity steel of a desired use.

Slag plays a major role in the steelmaking process, and slag removes impurities such as phosphorus and sulfur that may exist in the steel, and forms a film between molten steel and the atmosphere to reduce heat loss and refine the slag. It prevents the river from recombining with O, N, H, etc. in the atmosphere.

 Non-metallic inclusions (O, S, P, etc.) contained in steel deteriorate the properties of steel. Especially, oxides and sulfides greatly deteriorate the properties of steel. Therefore, it is essential to remove these impurities in steelmaking processes such as electric furnaces and converters. to be. Quicklime (CaO) is the most widely used degassing agent to remove impurities due to its excellent thermodynamic dehydration limit and low price, but its high melting point (2,570 ℃) results in slow reaction rate and increased dehydration time. There is a problem that the furnace temperature must be maintained above the melting point (1,400 ° C.) of steel for slag flowability. In addition, if the composition is inappropriate, impurities such as sulfur and phosphorus dissolve into slag again from the slag, and if the melting point is high, the internal temperature of the furnace should be high, which increases the operating time and the components necessary for the steel (Al, Si, Ti, Mn, etc.). ) May be absorbed into slag. In other words, if the optimal slag is not produced, not only economic loss (refractory life, increased power consumption, etc.) occur in the steelmaking process, but also steel quality cannot be secured.

In order to solve this problem, in most steelmaking processes, the composition of slag is changed by adding a solvent. Most of the solvents used in Korea use a CaF ₂ system that can melt slag at low temperatures and greatly increase the flowability of the molten slag. CaF ₂ reliably improves slag fluidity in a short time, but affects the CaO-Al ₂ O ₃ bonds of the refractory, causing refractory dissolution, and causing environmental problems such as fluorine gas generation and fluorine leaching during slag recycling. do. In addition, the CFC proliferation treaty that entered into force in early 1996 and domestic imports of fluorspar ore have been gradually avoided and suppressed. The domestic import price of fluorspar is about $ 140 per ton as of 2003.

The product developed to solve the problems of CaF ₂ solvent and to secure the slag outflow ability and fluidity is a solvent mainly composed of CaO · Al ₂ O ₃ (CA) system. However, this product has disadvantages of higher slag melting point and lower fluidity than CaF2. In addition, since calcined and calcined bauxite is mixed and calcined and manufactured, there is a problem in that the manufacturing cost is high and a manufacturing technology and a new manufacturing process must be added for mass production. Although some CA solvents are manufactured and used in Korea, most of them are still imported from overseas ($ 180 / ton as of 2003).

However, domestic products are not developed and established under the correct conditions, but are simply crushed and supplied with only the CA-based slag among the slag generated in the steelmaking process. Therefore, when the solvent is added to the steelmaking process, problems such as melting of the slag, increase in viscosity and working time may occur.

Looking at the status of foreign technology development, CA-based solvent was developed by Lafarge of France in the early 1990s when the regulation of CaF ₂ began, and was mainly produced in Europe and the United States until 1998, but in 1999 Since then, the company has been producing OEMs in China, which is rich in raw materials (quick lime and bauxite) and has a rapid growth in the steelmaking raw material market. In the United States, Alumica has purchased C · A slag from domestic steelmakers, which manufactures high-purity KID steels, since 1995, and sells it as a raw material for calcium aluminium to steelmakers, refractory producers, and cement producers. In Japan, steelmaking solvents are produced and sold, mainly from existing lime manufacturing companies. Steelmaking solvents produced in Japan are characterized by the production of new adjustment components by mixing other raw materials with CA raw materials to produce a variety of functionality. In particular, it is a great advantage to develop and sell a solvent for slag seed, which has a low melting point and can also perform the role of slag at the same time. In addition, it is a product that greatly reduces the load of steelmaking refining due to the rapid generation of environmentally friendly products and slag without addition of fluorspar. As a result, the company has announced that it has achieved the effects of shortening steelmaking operation time, reducing power consumption (20% level), and improving desulfurization rate (about 25%). (Product name Calsip, etc.-Yabashi 石灰 工業 株式會社, etc.)

Therefore, research should be carried out in Korea to secure technology superior to products of developed countries such as Japan, and technological advancement should be made accordingly. In addition, the completion of product development and production should replace imports and further export to developed countries.

Therefore, the present invention can improve the fluidity by forming the melting point of the slag at the temperature equal to or less than CaF ₂ and also to provide a solvent considering the extended life of refractory life and environmental protection by intangible solvents, such as CA-based solvents. The purpose.

In addition, an object of the present invention is to provide a new concept of a solvent acting as a seed (sed) of the slag to maximize the low-temperature molten slag production / solvent efficiency and thereby minimize the steelmaking refining load.

In the study of the present inventors for achieving the above object, when the CA solvent is present in the ratio of CaO and Al ₂ O ₃ in the range of 0.8-1.5: 1, the liquid phase is formed from about 1400 ℃ lower than the other composition ratio However, in order to lower the melting point of the solvent and slag and to control the viscosity of the slag, it is impossible to adjust only the composition ratio of CaO and Al ₂ O ₃ , and correct the third component. 1 to 2, the melting temperature decreases as the system changes from a two-component system to a three-component system, so that the melting temperature decreases due to correction of an appropriate component (SiO _2, etc.) and the three-component system is adjusted. If expensive pure raw materials are used for this purpose, economic losses may be increased. Therefore, appropriate industrial wastes must be utilized, and solvents must be produced in steel mills in order to act as slag seeds. The results of experiments using various correction components, focusing on the fact that minerals of the same or similar composition as slag are contained, and that the melting point of the mineral added to the solvent is low or the melting point of the solvent can be lowered after mixing. The present invention was completed by discovering that the use of fly ash, aluminum metal, and handmade slug as a correction component can provide a solvent that meets the purpose.

Therefore, according to the present invention, for steelmaking refining using hand-made slag containing 60-84 wt% of calcium aluminate-based mini-mill refining slag, 8-16 wt% of metal aluminum, 4-16 wt% of fly ash and 4-12 wt% of handmade slag. A low temperature solvent composition is provided.

In the present invention, the calcium aluminate-based mini mill refining slag carries a step of separately cooling the mini mill refining slag generated in the mini mill steelmaking process, and the cooled mini mill refining slag, such as a jaw crusher or a cone crusher. Crushing process using the crushing equipment of 50mm or less, and crushing the crushed mini-mill refining slag to a size of 3mm or less by using a grinding machine such as a hammer mill or a roller mill. A process of sorting the crushed and milled mini mill refined slag into a size of 3 mm or less and a mini mill refined slag of more than 3 mm using a particle size sorter; and a mini mill refined slag of 3 mm or less selected in the sorting step. It can be prepared by a process for removing impurities such as iron oxide contained in the mini-mill refined slag using a magnetic separator.

Preferably, the low temperature solvent composition of the present invention does not contain CaF ₂ .

Hereinafter, the present invention will be described by way of examples.

[Examples and Comparative Examples]

The slag melting point, the product melting point, the discharge rate and the slag fluidity evaluation method used in the following Examples and Comparative Examples are as follows.

Melting point: The sample is placed in a chamber type electric furnace using Super Kanthal, and the melting point of slag is measured by dusting while raising the temperature at a rate of 2 ° C / min ± 1 ° C / min after 1,000 ° C. A sample made by mixing a solvent, the temperature when the solid sample remaining in the liquefied sample is completely liquefied, the end point of the melting point, and the product melting point as the solvent sample, when the solid sample remaining in the liquefied sample is completely liquefied. Is the end point of the melting point. The solvent sample is prepared by compression molding by adding a binder. As the binder, a conventional binder used for preparing a steelmaking solvent such as molasses and liquid sodium silicate may be used. In this example, a molasses stock solution was used.

* Discharge rate and slag fluidity: The sample was measured in a Chanber-type electric furnace using Super Kanthal, heated to a rate of 5 ° C./min±1° C./min up to 1500 ° C., and then calcined at 1,500 ° C. for 30 minutes.

% Withdrawal = {[% S] ₀ -[% S]} ÷ [% S] ₀ × 100

(Where [% S] is wt% of sulfur in molten steel after operation and [% S] is wt% of sulfur in raw material before operation.)

Slag flowability is the percentage of iron content in the slag (wt%) when slag is excluded from the furnace.

[Control]

The slag melting point was measured for iron-containing dust of about 1 mm in particle size. The results are shown in Table 1.

Comparative Example 1

The slag melting point, product melting point, outflow rate, and slag fluidity were measured using 4.33 parts by weight of mini mill refined slag of 3 mm or less, which was broken and pulverized and removed impurities such as iron oxide by 100 parts by weight of iron-containing dust having a particle size of about 1 mm. The results are shown in Table 1.

 [Examples 1 to 24]

100 parts by weight of iron-containing dust with a particle size of about 1 mm, using 4.33 parts by weight of a solvent containing three components of metal aluminum, fly ash, and hand slag in a ratio as shown in Table 1 in the mini-mill refined slag of Comparative Example 1 Slag melting point, product melting point, outflow rate and slag flowability were measured. The results are shown in Table 1.

division Sample number Solvent Ingredients and Content (wt%) Melting point (℃) Discharge rate (%) Slag fluidity (%) Mini Mill Metal Al. Fly ash Wood slag Slag melting point Product melting point Control dust - - - - 1550 - - - Comparative example One One 100 - - - 1520 1410 35.14 5.31 Example One 2 84 8 4 4 1480 1360 43.03 4.70 2 3 80 8 8 4 1460 1340 46.81 4.65 3 4 76 8 12 4 1450 1330 43.75 4.52 4 5 72 8 16 4 1440 1330 50.27 4.54 5 6 80 8 4 8 1475 1320 51.64 4.32 6 7 76 8 8 8 1450 1330 56.76 4.19 7 8 72 8 12 8 1460 1280 67.65 4.17 8 9 68 8 16 8 1415 1255 69.36 4.17 9 10 76 8 4 12 1455 1270 66.92 4.26 10 11 72 8 8 12 1440 1270 66.54 4.35 11 12 68 8 12 12 1440 1270 65.25 4.44 12 13 64 8 16 12 1440 1270 65.86 4.48 13 14 76 12 4 8 1460 1360 50.16 4.77 14 15 72 12 8 8 1460 1360 56.45 4.67 15 16 68 12 12 8 1450 1350 54.24 4.74 16 17 64 12 16 8 1440 1370 59.35 4.59 17 18 72 12 4 12 1455 1370 60.69 4.74 18 19 68 12 8 12 1450 1360 61.81 4.45 19 20 64 12 12 12 1450 1350 58.76 4.26 20 21 60 12 16 12 1410 1310 64.38 4.16 21 22 72 16 4 8 1440 1360 70.13 4.51 22 23 68 16 8 8 1435 1350 68.65 4.54 23 24 64 16 12 8 1420 1340 65.77 4.29 24 25 60 16 16 8 1435 1350 62.54 4.31

From the results of Table 1 and the graphs of FIGS. 3 to 6 based thereon, when the metal aluminum, fly ash, and hand slag three components are added as correction components, the product melting point and slag melting point are low while the content of the mini-mill refined slag is greatly reduced. In addition, it can be seen that the low-flow type solvent having high slag flow rate and low slag flowability can be manufactured.

As described above, the low-temperature type solvent according to the present invention is for slag seed, which has a low content of calcium aluminate and has a low melting point and can also perform the role of slag at the same time. In addition, the load of steelmaking refining due to the rapid generation of slag can be greatly reduced, thereby providing the effect of shortening the steelmaking operation time, reducing the amount of power, and improving the desulfurization rate.

Claims (3)

A low-temperature solvent composition for steelmaking refining using a hand-made slag containing 60 to 84 weight% of calcium aluminate-based fine milling slag, 8 to 16 weight% of metal aluminum, 4 to 16 weight% of fly ash, and 4 to 12 weight% of hand slag. The process of claim 1, wherein the mini mill refining slag is transported and transported separately by mini mill refining slag generated in the mini mill steelmaking process, and the step of crushing the cooled mini mill refining slag to a size of 50 mm or less, and the crushed mini mill Grinding the refined slag to a size of 3 mm or less, separating the crushed and milled mini-mill refined slag into a size of 3 mm or less and a fine mill refined slag of more than 3 mm using a particle size separator, and the sorting step Low-temperature solvent composition for steelmaking refining using a hand-made slag, characterized in that it was manufactured through the process of removing iron oxide from the fine mill refined slag of less than 3mm screened in. The low-temperature solvent composition for steelmaking refining using hand slag according to claim 1, which does not contain CaF ₂ .

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