KR20100071660A - Dephosphorous flux for femn, recycling method of byproduct from dephosphorizing for femn, recalling method of byproduct from dephosphorizing for femn and dephosphorous flux for steel making - Google Patents

Abstract

PURPOSE: A dephosphorizing agent for FeMn, a recycling method of byproducts from the dephosphorizing for FeMn, a recovering method of byproducts from dephosphorizing for FeMn and a dephosphorizing agent for steel making are provided to reduce the discharge amount of carbon dioxide by collecting carbon dioxide produced during dephosphorization of FeMn and recycle dust produced during the process. CONSTITUTION: In a dephosphorizing agent for FeMn, one or more flux selected among Al2O3, NaF, and Na3AlF4 are mixed in BaCO3. The content of Al2O3 or Na3AlF4 is 5~10weight% and that of NaF is 5~20 weight%. In case that the melting temperature of FeMn is 1400°C, Na3AlF4 is selected as flux.

Description

Dephosphorous flux for FeMn, Recycling method of byproduct from dephosphorizing for FeMn, Recalling method of byproduct from dephosphorizing for FeMn and Dephosphorous flux for steel making}

The present invention relates to a dephosphorization agent for ferro-manganese, and more particularly, a low-cost solvent is mixed with BaCO ₃ , a dephosphorizing additive used in the production of ferro-manganese, to improve the dephosphorization rate and maintain an excellent delineation rate even at high temperatures. It relates to a dephosphorization agent for ferro-manganese.

The present invention also relates to a method of recycling by-products of ferro-manganese which can recycle and recover soda ash and carbon dioxide, which are by-products generated in the process of dephosphorization of ferro-manganese, a method of recovering the delineation of by-products of ferro-manganese, and a debinding agent for steelmaking.

Ferro-manganese used for steelmaking ferroalloy is high carbon ([C] <7.5% or less, based on KS standard KSD3712), heavy coal ([C] <2.0% or less, based on KS standard KSD3712) and low coal ([C] <1.0% or less, based on KS standard KSD3712).

The general process for producing such ferro manganese is prepared by charging manganese ore and reducing agent coke and slag forming agent in an electric furnace to reduce the manganese ore in the form of oxide using carbon of coke. As such, ferro-manganese produced in an electric furnace using coke is obtained in the form of high-carbon ferro-manganese in which carbon is saturated in a product due to coke as a reducing agent.

Thus, a method of producing bicarbonate or low-carbon ferro-manganese has been proposed, unlike the method described above. For example, a method of producing low-carbon ferro-manganese by melting and reducing Mn ore in an electric furnace using SiMn, or a method of producing low-carbon ferro-manganese by blowing oxygen into molten high-carbon ferro-manganese and decarburizing it is used. .

Phosphorus (P) content of commonly used ferro manganese is currently high as 0.4% or less as defined by KS and JIS standards, and phosphorus (P) content is also 0.1 to 0.2 even in ferro manganese which is used for steelmaking. It is relatively high in%.

However, in addition to carbon, phosphorus has a great influence on the properties of the steel depending on its content in the steelmaking process. In the case of carbon, high carbon ferro manganese or medium / low carbon ferro manganese can be selectively used depending on the carbon content of the steel produced. However, in the case of phosphorus (P), high carbon, heavy carbon, and low carbon ferro manganese have the same phosphorus content. Therefore, there was no way to avoid the influence of phosphorus (P) in ferro-manganese even by changing the type of ferroalloy.

In general, phosphorus (P) is present as an impurity in the steel, and since it impairs the quality of steel products such as causing high temperature brittleness, except for special cases, efforts are made to lower the content of phosphorus (P) in molten steel. Therefore, when using ferro-manganese ferroalloy, the increase in the concentration of phosphorus (P) in the molten steel by the ferroalloy should be taken into account, which may cause the use of ferro-manganese.

Thus, a method for producing low phosphorus ferro manganese with low phosphorus (P) has been proposed.

The method for preparing low ferro-manganese includes beneficiation by operating only high-quality manganese ores with low phosphorus (P) content, and slag or low phosphorus (P) ore produced in the high-carbon ferro-manganese manufacturing process. Al, Ca, etc.) has been proposed, but there are problems such as rising price of high quality manganese ore and inadequate mass production.

Thus, a method for producing low ferro-manganese has been proposed by subjecting directly to high-carbon ferro-manganese produced in an electric furnace.

The method of directly dephosphorizing manganese ferro-manganese can be roughly divided into reduction and deoxidation. Reduction Tallinn phosphide phosphorus (P) of the ferro-manganese and the method of removing in the form of a _{(Ca 3 P 2, Mg 3} P 2 , etc.), oxidation Tallinn cargo phosphate phosphorus (P) of ferro manganese (Ba ₃ ( PO ₄ ) _2, etc.).

In the case of reduced Tallinn, it is known to mainly use Ca or Mg. In the case of reduced tallin, the tallin efficiency is known to be high, but in the case of Ca, it is known that delineation is impossible in high-carbon ferro-manganese due to the formation of carbides. In addition, the delineation product Ca ₃ P ₂ , Mg ₃ P ₂ has a problem of generating phosphine which is a toxic gas reacts with water.

In the case of thallium oxide, BaCO ₃ , BaO, BaF ₂ , BaCl ₂ , CaO, CaF ₂ , Na ₂ CO ₃ , Li ₂ CO ₃ and the like are known to be used. Among them, the Ca-based, such as low delineation efficiency, Na and Li-based high vapor pressure had a problem that the bokrin phenomenon occurs. Therefore, BaCO ₃ and BaO are mainly used, but BaO ₃ does not have an oxygen source capable of oxidizing phosphorus (P), and therefore oxidants are used together. In addition, in the case of using BaCO ₃ or BaO, the slag generated is generated in a solid phase, so that delineation efficiency is lowered. Thus, BaCl ₂ or BaF ₂ is used as a solvent to solve this problem. However, in case of using BaCl ₂ , slag on top of ferro-manganese is scattered due to facility contamination and vaporization of Cl group due to the highly corrosive Cl group, and BaF ₂ is currently difficult to be industrially produced in mass production. The problem is that the price is higher than that of ferro manganese. Therefore, when the amount of BaF ₂ used is large, the cost of the solvent added to the flux is very high, and thus there is a problem in establishing an economical process for producing Tallinn flux.

The present invention has been made to solve the above problems, in the ferro-manganese dephosphorization agent containing BaCO ₃ as a main component, ferro manganese can obtain the same or higher delineation rate without using expensive BaF ₂ Provide a dephosphorization agent.

In addition, there is provided a dephosphorizing agent for ferro manganese which can obtain excellent delineation rate even at high temperatures.

The present invention also provides a method and a product capable of recycling and recovering soda ash and carbon dioxide generated in the fermentation process of ferro manganese.

The dephosphorizing agent for ferro manganese according to the present invention is characterized in that BaCO ₃ is mixed with at least one solvent selected from Al ₂ O ₃ , NaF, and cryolite (Na ₃ AlF ₄ ).

The Al ₂ O ₃ or cryolite (Na ₃ AlF ₄ ) is characterized in that 5 ~ 10wt% is mixed.

The NaF is characterized in that 5 to 20wt% is mixed.

The melting temperature of the ferro manganese is characterized in that 1350 ℃ or more, in particular, when the melting temperature of the ferro manganese is more than 1400 ℃, characterized in that the solvent is mixed with NaF or cryolite (Na ₃ AlF ₄ ).

The method of recycling by-products of the delineation of ferro-manganese according to the present invention includes delineating ferro-manganese with a dephosphorizing agent in which NaF or cryolite (Na ₃ AlF ₄ ) is mixed with BaCO ₃ , and the dust generated in the delineation step is delineated for steelmaking. It is characterized by recycling zero.

The dust is characterized in that the Na gas generated during the reaction of the ferro-manganese and the Tallinn claim that exposure to oxygen is Na ₂ O is produced and generated on the reaction with CO ₂ wherein the Na ₂ O is generated in Tallinn step .

The generation of Na ₂ O is characterized in that the Na gas is reacted with oxygen in the atmosphere.

Steelmaking dephosphorization agent according to the present invention is characterized in that Na ₂ CO ₃ produced by the method for recycling the delineation by-products of ferro manganese.

The method for recovering the delineation by-product of ferro-manganese according to the present invention includes dephosphorizing ferro-manganese with a dephosphorizing agent in which NaF or cryolite (Na ₃ AlF ₄ ) is mixed with BaCO ₃ , and Na gas generated in the delineation step is converted into oxygen. by creating the Na ₂ O gas exposure, and then reacted with CO ₂ to the Na ₂ O generated in Tallinn phase, it characterized in that the recovery of CO _2.

According to the present invention, it is possible to obtain a dephosphorization agent that can increase the dephosphorization efficiency to be equal or higher even if a low-cost solvent is used in place of BaF ₂ that is conventionally used.

In addition, even at high temperatures, it shows superior delineation efficiency compared to conventional solvents, and by capturing CO ₂ generated during delineation of ferro manganese, CO ₂ emissions can be reduced, and the dust (soda ash, Na ₂ CO ₃ ) produced at this time is steel-making. There is an effect that can be recycled to the flux.

Hereinafter, the debinding agent for ferro manganese according to the present invention will be described in detail.

First, in the production of ferro-manganese, the phthalate oxide reaction is known to form phosphorus (P ₂ O ₅ ) by reacting with oxygen to form phosphorous oxide (P ₂ O ₅ ), followed by being collected by a high basic material to form a stable phase. For this reason, high basic oxides are used. In the case of using such a high basic oxide, a solvent for lowering the melting point of the slag is used because it must exist in a liquid state to promote the reaction with the phosphate.

Therefore, the ferro manganese dephosphorization agent according to the present invention is a dephosphorization agent containing BaCO ₃ as a main component, and Al ₂ O ₃ , NaF or feldspar (Na ₃ AlF ₄ ) is mixed with BaCO ₃ instead of BaF ₂ which is a commonly used solvent. It is done by

Solvents, Al ₂ O ₃ , NaF or cryolite (Na ₃ AlF ₄ ), increase the rate of diffusion of phosphate toward BaCO ₃ particles by liquefying the surface of BaCO ₃ particles injected for Tallinn, thereby increasing the Tallinn reaction. do.

The BaCO mixing amount of the _third and maeyongje is maeyongje the Al ₂ O _3, or Na ₃ AlF case _4, BaCO ₃ 90 ~ 95 wt% and Al ₂ O _3, or Na ₃ AlF ₄ is 5 ~ 10wt% of a mixture may be made of Do.

In addition, when the solvent is NaF, it is preferable that BaCO ₃ 80-95 wt% and NaF 5-20wt% are mixed.

Hereinafter, the present invention will be described in detail through specific and various examples and comparative examples.

In this embodiment, in order to determine the effect of the solvent, the delineation rate was measured by reacting with high carbon ferro manganese using a solvent having a composition as shown in Table 1 below.

The experimental method is as follows.

20 g of high-carbon ferro-manganese was mixed in a carbon crucible with BaCO ₃ and a solvent in a weight ratio below, and the total was added to the crucible to be 6 g, followed by an equilibrium reaction at 1350 ° C. for 5 hours, followed by phosphorus (P) in ferro-manganese. The content of was measured. The delineation rate according to the phosphorus (P) concentration change before and after the experiment was calculated in the same manner as in Equation 1 below.

division Solvent Tallinn Kinds Content (wt.%) Comparative Example 1 - 0 52.3 Comparative Example 2 BaF ₂ 10 65.2 Comparative Example 3 BaF ₂ 20 70.7 Comparative Example 4 BaF ₂ 30 73.6 Comparative Example 5 CaF ₂ 10 69 Comparative Example 6 CaF ₂ 20 67.1 Comparative Example 7 BaCl ₂ 10 32.1 Comparative Example 8 BaCl ₂ 20 43.1 Comparative Example 9 BaCl ₂ 30 34 Comparative Example 10 SiO ₂ 15 -5 Comparative Example 11 SiO ₂ 30 -2.8 Example 1 Al ₂ O ₃ 5 65.1 Example 2 Al ₂ O ₃ 10 54.6 Example 3 NaF 5 67.4 Example 4 NaF 10 70.2 Example 5 NaF 15 66.6 Example 6 NaF 20 61.8 Comparative Example 12 NaF 30 40.1 Comparative Example 13 NaF 40 24.6 Example 7 Na ₃ AlF ₄ 5 64.7 Example 8 Na ₃ AlF ₄ 10 68.7 Comparative Example 14 Na ₃ AlF ₄ 15 40.9 Comparative Example 15 Na ₃ AlF ₄ 20 27.3

As can be seen in Table 1, in the case of Comparative Example 1 using only BaCO ₃ without a solvent, the delineation rate was about 52.3%. Further, in the case of the known in the art maeyongje of BaF _2, Comparative Examples 2 to 6 by the addition of CaF _2, 10 ~ 30wt% could see that Tallinn rate is significantly increased to 65.2 ~ 73.6%. However, in the case of Comparative Examples 7 to 9 in which BaCl ₂ was mixed, the delineation rate was low, which is considered to be an effect due to the phenomenon that all slag of the upper slag was scattered and consumed when BaCl ₂ was used.

In addition, in order to investigate the effect of adding the acidic slag to the high basic slag, the delineation rate was determined using the acidic slag SiO ₂ and Al ₂ O ₃ as the solvent.

In the case of Comparative Examples 10 and 11 to which SiO ₂ was added, it was confirmed that delineation did not occur. However, in Examples 1 and 2 to which Al ₂ O ₃ was added, it was found that the delinquency rate increased. However, in the case of Example 1 in which Al ₂ O ₃ was added 5 wt%, the same delineation rate as in Comparative Example 2 in which 10 wt% BaF ₂ was added, and in Example 2 in which 10 wt% Al ₂ O ₃ was added It can be seen that the delineation rate similar to that of Comparative Example 1 without mixing the solvent was shown. Therefore, it was found that as the amount of Al ₂ O ₃ increased, the delinquency rate tended to decrease. This can be seen as the phenomenon occurs because the basicity in the slag produced by the Tallinn reaction decreases as the content of Al ₂ O ₃ increases. Thus, if the addition of Al ₂ O ₃ as maeyongje, it is preferable to add about 5 ~ 10wt%.

Fluorine (F) decomposes the oxygen bond in the slag to improve the flowability of the slag is a technique known in steelmaking slag refining. Therefore, in the present invention, the delineation rate was determined by using NaF as a solvent in the fluoride.

As can be seen from the results of Examples 3 to 6 of Table 1 and Comparative Examples 12 and 13, it was found that the addition of a small amount compared to the conventional BaF ₂ (Comparative Examples 2 to 3) increases the delineation rate. .

And in order to confirm the mixing amount of titration NaF, delining ability was investigated, changing NaF mixing amount. As shown in Examples 3 to 5 of Table 1, when the NaF content is relatively low, it can be seen that the delinquency ability is improved compared to BaF ₂ , and as shown in Example 6, the delinquency rate is up to 20wt%. This was found to be higher than 60%. However, as shown in Comparative Examples 12 and 13, when the NaF was increased to 30% or more, it was found that the Tallinn rate decreased rapidly. The reason is that Na is generally known as a metal having a low vapor pressure. Therefore, when NaF is added, Na is vaporized to scatter slag and molten metal, and molten metal is scattered. Therefore, when NaF is added as a solvent, it is preferable to add about 5-20 wt%.

As described above, it was confirmed that the use of NaF and Al ₂ O ₃ as a solvent in BaCO ₃ enhances the Tallinn effect. Accordingly, the delineation rate was determined using cryolite (Na ₃ AlF ₄ ), which is a material that can simultaneously obtain the effects of NaF and Al ₂ O ₃ .

As a result, it was found that in the case of Examples 7 and 8 in which 5 wt% and 10 wt% of cryolite (Na ₃ AlF ₄ ) were mixed, the delineation rate was increased. On the other hand, in the case of Comparative Examples 14 and 15 in which the mixing amount of the cryolite (Na ₃ AlF ₄ ) is more than 15wt%, it was found that the delinquency rate fell below 50%, because the content of NaF and Al ₂ O ₃ described above. This could be interpreted as the same phenomenon that occurs as the increase. Therefore, when adding cryolite (Na ₃ AlF ₄ ) as a solvent, it is preferable to add about 5-10 wt%.

When BaCO ₃ is used as the dephosphorization agent through the present example, Al ₂ O ₃ is mixed in an amount of 5 to 10 wt% or less, or NaF is mixed in an amount of 5 to 20 wt%, instead of BaF ₂ , which is conventionally used as a solvent. When the amount of about 5 wt% to 10 wt% was used, it could be seen that it can be used as a dephosphorization agent for ferro-manganese having a higher delineation rate than without using a solvent. At this time, If the content of _{Al 2 O 3, Na 3 AlF} 4 and cryolite added to the BaCO ₃ is less than 5 wt% difficult to exert sufficient function as maeyongje since it is difficult to expect the increase of the Tallinn ratio Al ₂ O _3, Na The lower limit of ₃ AlF ₄ and cryolite content is preferably more than 5 wt%.

Next, the temperature dependence of the dephosphorization agent for ferro manganese according to the present invention was examined.

1 is a graph showing a change in the delineation efficiency of the dephosphorization agent with temperature.

As shown in Figure 1 it can be seen that as the temperature increases in ferro-manganese, the Tallinn rate falls rapidly. This is the same phenomenon that occurs in the Tallinn reaction in the steelmaking process. The Tallinn reaction is exothermic and the lower the temperature, the higher the Tallinn rate. However, in the actual process, there is a problem in that the Tallinn reaction temperature cannot be kept low to secure the fluidity of the molten metal. Therefore, in the present embodiment, the melting temperature of ferro-manganese, that is, the temperature at which delineation proceeds, was increased by 1350 ° C and 50 ° C compared to 1350 ° C, and the delineation rate at 1400 ° C was investigated, and the results are shown in Table 2 below. It was.

division Solvent Tallinn Tallinn Change Kinds content 1350 ℃ 1400 ℃ Comparative Example 1 - 0 52.3 43.0 82% Comparative Example 2 BaF ₂ 10 65.2 46.1 71% Comparative Example 3 BaF ₂ 20 70.7 53.3 75% Comparative Example 5 CaF ₂ 10 69.0 43.1 62% Comparative Example 6 CaF ₂ 20 67.1 43.3 65% Example 1 Al ₂ O ₃ 5 65.1 40.3 62% Example 2 Al ₂ O ₃ 10 54.6 23.1 42% Example 3 NaF 5 67.4 60.1 89% Example 4 NaF 10 70.2 62.2 89% Example 5 NaF 15 66.6 55.9 84% Example 6 NaF 20 61.8 50.8 82% Comparative Example 12 NaF 30 40.1 24.9 62% Comparative Example 13 NaF 40 24.6 5.2 21% Example 7 Na ₃ AlF ₄ 5 64.7 43.3 67% Example 8 Na ₃ AlF ₄ 10 68.7 44.0 64% Comparative Example 14 Na ₃ AlF ₄ 15 40.9 18.7 46% Comparative Example 15 Na ₃ AlF ₄ 20 27.3 6.8 25%

As shown in Table 2, when BaF ₂ was used as a solvent (Comparative Examples 2 and 3), when the temperature was increased from 1350 ° C. to 1400 ° C., the thallination rate dropped to 71 to 75%, and CaF ₂ was decreased. When used as a solvent (Comparative Examples 5 and 6) it can be seen that the delineation rate drops to 62 ~ 65%, but when using NaF ₂ according to the invention as a solvent (Examples 3 to 6) 82 ~ 89 At the level of%, it was found that the reduction of delineation rate with temperature was smaller than that of other solvents.

In addition, in the case of using cryolite (Na ₃ AlF ₄ ) as a solvent (Examples 7 and 8), it was seen that the delineation efficiency decreased as the temperature increased to 64 to 67%. However, even in such a case, it was found that the delineation rate was high compared to 43%, which is the delineation rate in the case of not using a solvent (Comparative Example 1).

However, in the case of using Al ₂ O ₃ as a solvent (Examples 1 and 2), as the temperature is increased, the amount of reduction in the delineation rate was increased, which was found to be less effective as a solvent. Therefore, it was found that the use of a dephosphorization agent containing NaF ₂ and cryolite (Na ₃ AlF ₄ ) as a high-temperature delineation flux of 1400 ° C. or higher was advantageous in the field of operation. In particular, it will be preferable to use a dephosphorizing agent mixed with NaF ₂ .

Next, a process of dephosphorizing ferro manganese using the dephosphorization agent according to the present invention will be described, and a method of recycling Na ₂ CO ₃ (soda ash), which is a by-product generated by the delineation process, and a method of recovering CO ₂ gas will be described. would.

Most additives used as ferro manganese dephosphorizer mainly use carbonate such as BaCO ₃ . This is for oxidizing phosphorus (P) present in ferro-manganese using CO ₂ obtained in this reaction when the temperature of the additive rises when carbonate is added. However, the CO ₂ generated in the calcination reaction is not used for the whole amount reaction, and some will be released to the atmosphere. The amount of CO ₂ generated is changed according to the raw unit of the dephosphorizing additive, but when the raw unit is 100kg-flux / ton-Mn, the amount of CO ₂ generated from the additive added to desorb 1 ton of feron manganese is 22.3 kg. Since the amount of phosphorus (P) used in the oxidation is about 15% (for 0.2% P), about 18.7 kg of CO ₂ is released. In other words, to release 1 ton of ferro manganese, it releases about 19 kg of CO ₂ .

In the case of using NaF as a solvent, Na evaporates due to the high vapor pressure, and the Na gas evaporated immediately meets oxygen in the atmosphere and is oxidized to produce Na ₂ O. In this case, Na gas is sufficiently oxidized with only oxygen in the atmosphere without additional oxygen injection, but may be separately blown to promote the oxidation reaction of Na gas. Thus produced Na ₂ O is thermodynamically produced Na ₂ CO ₃ when it meets the surrounding CO ₂ . That is, in the case of adding 20 wt% NaF proposed in the present invention as a medium of ferro-manganese dephosphorizing agent, theoretically absorbs 9.45 kg of CO ₂ , which is about 50% of the amount of CO ₂ released, By-product Na ₂ CO ₃ is produced.

In order to determine whether such a phenomenon occurs, the dephosphorization reaction was performed using a dephosphorization agent mixed with BaCO ₃ and NaF of the present invention, at the same time, dust (dust) generated in the dephosphorization reaction was collected and analyzed by XRD. The results are shown in FIG.

Figure 2 is a graph showing the XRD measurement results of the dust generated when using the dephosphorization agent according to the present invention. As can be seen in Figure 2, the dust generated during the Tallinn process was found that Na ₂ CO ₃ is the main component. Thus produced Na ₂ CO ₃ (soda ash) is used as the delinquency flux in the steelmaking process, there is an effect that can be used as a debinding agent for steelmaking by collecting dust.

That is, when using the dephosphorization agent for ferro-manganese proposed in the present invention, as compared to the existing dephosphorization agent, as well as the effect of absorbing CO ₂ generated in the debinding process while having a higher dephosphorization efficiency, dust is recycled as an additive for delineation for steelmaking. It can work.

1 is a graph showing the change in the delineation efficiency of the dephosphorization agent with temperature,

Figure 2 is a graph showing the XRD measurement results of the dust generated when using the dephosphorization agent according to the present invention.

Claims (10)

In the dephosphorization agent for ferro manganese, A dephosphorizing agent for ferro-manganese in which BaCO ₃ is mixed with at least one solvent selected from Al ₂ O ₃ , NaF, and cryolite (Na ₃ AlF ₄ ). The method according to claim 1, The Al ₂ O ₃ or cryolite (Na ₃ AlF ₄ ) is a dephosphorizing agent for ferro manganese, characterized in that 5 to 10wt% is mixed. The method according to claim 1, The NaF dephosphorizing agent for ferro manganese, characterized in that 5 to 20wt% is mixed. The method according to claim 1, Deferring agent for ferro manganese, characterized in that the melting temperature of the ferro manganese is 1350 ℃ or more. The method according to claim 4, When the melting temperature of the ferro manganese is 1400 ℃ or more, As the maeyongje NaF or cryolite (Na ₃ AlF ₄ ) is mixed with a delineating agent for ferro manganese. Dephosphorizing ferro manganese with a dephosphorizing agent in which BaCO ₃ is mixed with NaF or cryolite (Na ₃ AlF ₄ ), Method for recycling the delineation by-products of ferro-manganese for recycling the dust generated in the delineation step as a desalting agent for steelmaking. The method according to claim 6, The dust is The ferro-manganese and the ferro-manganese, characterized in that the Tallinn The Na gas is exposed to oxygen Na ₂ O generated during the reaction is generated, the generated reacts with CO ₂ the Na ₂ O is generated in Tallinn step How To Recycle Tallinn By-Products. The method of claim 7, The generation of Na ₂ O is a method for recycling the delineation by-products of ferro-manganese, characterized in that the Na gas is reacted with oxygen in the atmosphere. Debinding agent for steelmaking, characterized in that Na ₂ CO ₃ prepared by claim 6 or 7. Dephosphorizing ferro manganese with a dephosphorizing agent in which BaCO ₃ is mixed with NaF or cryolite (Na ₃ AlF ₄ ), The Na gas to the exposure to oxygen generated in Tallinn step generates a Na ₂ O, and then, Tallinn by-product recovery process of the ferro-manganese to the Na ₂ O is reacted with CO ₂ generated in step Tallinn recovering CO _2.

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