KR100526132B1 - Method for Manufacturing Slag for Fertilizer and Cement Additive in Mini-Mill Process - Google Patents

Abstract

The present invention relates to a method for recycling the slag generated in the mini mill process, by re-injecting the slag remaining after the casting in the mini mill process to the refining furnace to increase the content of CaO and Al ₂ O ₃ in the slag In addition to increasing the utilization, it is intended to reduce the input of subsidiary materials, which is the purpose.

The present invention manufactures molten steel in an electric furnace and taps the manufactured molten steel into a refining furnace, and then in the mini-mill process of refining molten steel by adding quicklime and aluminum, and casting the refined molten steel, the slag remaining after the casting 60-80% of the slag after refining was added to the refining furnace and subsidiary materials were added.SiO ₂ : 2-3%, Al ₂ O ₃ : 30-38%, Fe ₂ O ₃ : 2-3%, CaO: 40 It relates to a method for producing a fertilizer raw material and cement admixture slag characterized in that the refining is less than -50%, MgO: 5-7%, and other: 10%.

According to the present invention, mini-refining slag can be re-introduced into the refining furnace to not only reduce the amount of side materials introduced into the refining furnace, but also to make the slag available as a calcining fertilizer and cement admixture. There is a useful effect that can lead to saving of resources.

Description

Method for manufacturing slag for fertilizer raw material and cement admixture in mini mill process {Method for Manufacturing Slag for Fertilizer and Cement Additive in Mini-Mill Process}

The present invention relates to a method for recycling slag generated in a mini mill process, and more particularly, to reduce the amount of side materials used by re-introducing the slag remaining after casting in a mini mill process and to use it as a fertilizer raw material and cement admixture. The present invention relates to a method for producing a slag that can be.

In the mini-mill process, refining furnace slag generated by the addition of quicklime and aluminum and other subsidiary materials is generated for the fine composition of the furnace slag generated by the input of quicklime and carbon in the electric furnace and molten steel produced in the electric furnace.

At present, electric furnace slag and refinery slag are difficult to recycle due to the composition of the composition.

However, the utilization of the sediment is far from the price competitiveness with natural aggregates such as quarries due to the long distance of transportation, and the leaching water of high pH (10-12) occurs due to the characteristics of slag including quicklime. There is a problem that there are many difficulties.

The present inventors have conducted research and experiments to solve the above problems of the prior art, and based on the results, the present invention proposes the present invention, and the present invention re-injects the slag remaining after the casting in the mini-mill process into the refining furnace. By increasing the content of CaO and Al ₂ O ₃ in the slag to increase the utilization of the slag as well as to reduce the amount of feedstock, the purpose is to.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated.

In the present invention, in the mini-mill process of manufacturing molten steel in an electric furnace and tapping the manufactured molten steel into a refining furnace, and then adding quicklime and aluminum to refine the molten steel and then casting the refined molten steel,

60-80% by weight of the slag remaining after the casting was re-injected into the refining furnace, and slag after refining was added to the slag after refining by SiO ₂ : 2-3% by weight and Al ₂ O ₃ : 30-38% by weight. Fertilizers and cement admixtures, characterized in that refining is carried out so that Fe ₂ O ₃ : 2-3% by weight, CaO: 40-50% by weight, MgO: 5-7% by weight, and other impurities: 10% by weight It relates to a method for producing molten slag.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

The present invention is applied to the mini-mill process of manufacturing molten steel in an electric furnace, tapping the manufactured molten steel into a refining furnace, then refining molten steel by adding quicklime and aluminum, and then casting the refined molten steel.

In the mini mill process, the electric furnace operation is a process of manufacturing molten steel by inserting scrap and molten iron into an electric furnace and then melting the scrap using an arc, and at this time, the slag of the furnace is added by input of quicklime and slag forming agent. Will occur.

The molten steel produced in the electric furnace is cast into a refining furnace (ladle), and slag is formed by injecting quicklime and aluminum into the refining furnace in which the molten steel is taken, and the molten steel is removed and cast in a machine.

At this time, the formed slag reacts with impurities in the molten steel to form semi-solid phase in the hearth due to the specific gravity difference, thereby insulating the furnace.

On the other hand, the slag remaining in the refining furnace after casting is contained in the pot and mixed with the furnace slag in the slag treatment plant, the slag composition generated at this time is difficult to develop the utilization of low lime and aluminum components.

Accordingly, in the present invention, 60-80% by weight of the slag remaining after the casting is re-injected, and slag after refining is added by adding quicklime and aluminum, which is an auxiliary material, to SiO ₂ : 2-3% by weight, Al ₂ O ₃ : 30- 38% by weight, Fe ₂ O ₃ : 2-3% by weight, CaO: 40-50% by weight, MgO: 5-7% by weight, and other impurity components: 10% by weight or less. The dosage of 9-12 kg per tonne of molten steel and 0.5 to 0.8 kg of tonne of molten steel are preferred.

When re-injecting 60-80% by weight of the slag remaining after casting according to the present invention can reduce the input amount of the _secondary raw material, and also because the content of CaO and Al ₂ O _{3 in} the slag is increased than that of the conventional slag You can widen your wife.

Representative applications include fertilizer raw materials and cement admixtures.

In the present invention, the amount of slag to be re-injected is set to 60-80% in consideration of the size of the ladle (refining furnace), the real steel milling ratio and the slag composition composition.

division Alkaline [CaO content (wt%) +1.39 x MgO content (wt%)] Hazardous Ingredients Slaked lime 60 wt% or more - Limestone 45 wt% or more - Lime Goto 53 wt% or more - Busan lime 60 wt% or more 0.01 wt% nickel, 0.1 wt% chromium, 0.04 wt% or less titanium Busan lime 45 wt% or more 0.01 wt% nickel, 0.1 wt% chromium, 0.04 wt% or less titanium

In view of the calcined fertilizer process standard of Table 1, the slag prepared according to the present invention has an alkalinity of 50 to 60% by weight, and also because the harmful metal is not added to the fertilizer utilization, such as nickel in the electric process, limestone fertilizer And lime goto Busan lime fertilizers can be seen that the slag crushing slag itself meets the particle size only need to use the fertilizer alone without the need for additional additives.

In addition, the use of the slag prepared according to the present invention as a high-grade fertilizer such as Busan slaked lime fertilizer and slaked lime fertilizer may be slightly insufficient compared to the alkali standard of 60% by weight, but when a small amount of quicklime having an alkalinity of 90% by weight is used. This becomes possible.

In addition, the slag prepared according to the present invention is not only high in the content of CaO but also high in the aluminum oxide component that generates a rapid flocculation reaction when fine, it is also possible to utilize the cement as admixture.

Cement admixtures are materials that do not affect the major quality of cement or are added to improve the quality. General cement admixtures include fly ash generated in power plants and regenerated slag generated in steel mill blast furnace processes.

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

(Example 1)

After re-injecting 60-80% by weight of the slag remaining after casting according to the present invention to the refining furnace (150 tons) and refining by adding CaO and Al ₂ O ₃ as a secondary raw material as shown in Table 2 below, The composition was investigated and the results are shown in Table 3 below.

division Quicklime input (per ton of molten steel) Aluminum input amount (per molten steel) Power consumption Refining time Conventional method 12-15 kg 0.7 ~ 1.0㎏ 33 ~ 37 kwh 41-44 minutes / time Invention method 9-12 kg 0.5 ~ 0.8㎏ 30-33 kwh 37-40 minutes / time

division SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ CaO MgO Other Impurity Components Conventional slag (wt%) 1-2% 20-25% 7-8% 30-35% 3-5% - Slag of the present invention (% by weight) 2-3% 30-38% 2-3% 40-50% 5-7% below 10

As shown in Table 2, according to the present invention, the amount of auxiliary raw materials, such as quicklime and aluminum, was reduced by about 20 to 30% compared to the conventional method. In particular, the heat loss caused by slag mixing was feared, but the slag layer thickness according to the mixing was increased. Increasing the insulation effect by increasing 20% from 90-100mm to 110-120mm, and the slag component which completed the reaction such as deoxidation increases the reaction efficiency in the refining furnace, so the overall power is 32 kwh at 35 kwh / ton It can be seen that the reduction is about 10% per ton.

In addition, the present invention method can be seen that the refining time is shortened compared to the conventional method.

Example 2

After mixing the present invention slag having the composition of Table 3 in Example 1 in the amount of the following Table 4 to the cement, the setting time, powder strength and compressive strength were measured, and the results are shown in Table 4 below.

division Setting time Powder level (㎠ / g) Compressive strength (㎏f / ㎠) Min Termination (Hr) 3 days 7 days 28 days No refined slag added 286 9.0 4,200 180 280 445 1% by weight of slag of the present invention 90% of crushability 290 9.1 3,780 175 271 440 100% combustibility 285 8.9 4,200 182 287 453 3 wt% added slag of the present invention 90% of crushability 290 9.0 3,780 172 265 432 100% combustibility 280 8.7 4,200 182 289 455

As shown in Table 4, when the powder level is 90% of the cement, the condensation time is similar to that of the present invention without adding the slag, but the compressive strength is slightly reduced. As the solidification time is shortened and the compressive strength is also increased, it can be seen that the slag of the present invention has a great effect as a cement admixture.

This is judged to be due to the quickness of the refined slag aluminum oxide component, and as a result, the slag of the present invention can be seen that it can be used as a admixture by mixing with cement through crushing of cement powder degree.

As described above, the present invention can not only reduce the amount of subsidiary material introduced into the refining furnace by re-introducing the minimill refining slag into the refining furnace, but also by increasing the CaO and Al ₂ O ₃ content in the slag, By enabling the use as a cement admixture, there is a useful effect that can lead to the reduction of treatment costs and the saving of resources through waste recycling.

Claims (1)

In the mini-mill process of manufacturing molten steel in an electric furnace, tapping the manufactured molten steel into a refining furnace, refining molten steel by adding quicklime and aluminum, and then casting the refined molten steel, In the material 60 to 80 percent by weight of the slag which remains after the molding in the refining and the additives added as a calcium oxide and aluminum in the molten steel per ton of 0.5-0.8kg per ton of molten steel after the slag refining 9-12kg SiO _2: 2-3 % By weight, Al ₂ O ₃ : 30-38% by weight, Fe ₂ O ₃ : 2-3% by weight, CaO: 40-50% by weight, MgO: 5-7% by weight, and other impurity components: 10% by weight or less Manufacturing method of slag for fertilizer raw materials and cement admixtures in the mini-mill process, characterized in that to refine to