KR101381856B1 - Flux for dephosphorizing ferromanganese - Google Patents

Abstract

The present invention relates to a flux for dephosphorization of ferro-manganese, wherein the flux for dephosphorization of ferro-manganese is characterized by comprising a mixture of BaCO ₃ and SrCO _{3 in} the de-lining flux for producing low ferro-manganese. Compared with BaO-based fluxes used for dephosphorization of ferro manganese, the dephosphorization ability is very excellent, and the dephosphorization efficiency is superior to conventional solvents even at high temperatures.

Description

Fluorine fluxes for ferro-manganese {FLUX FOR DEPHOSPHORIZING FERROMANGANESE}

The present invention relates to a flux for dephosphorization of ferro-manganese, and more particularly, to a flux used in the dephosphorization process of molten ferro-manganese which is excellent in delinquency even at high temperatures and can reduce the amount of slag generated as a by-product.

The manufacturing process of ferro manganese is carried out by charging manganese ore and reducing agent coke and slag forming agent into an electric furnace, and reducing the manganese ore which is an oxide form using the carbon of coke. Thus, the ferromanganese produced by using coke in the electric furnace is obtained in the form of high carbon ferro-manganese in which carbon is saturated in the product due to the coke as a reducing agent.

On the other hand, the phosphorus (P) content of commonly used ferro manganese appears to be high as 0.4% or less as currently prescribed in KS and JIS standards, and the phosphorus (P) content is also 0.1 in ferro manganese which is frequently used for steelmaking. To 0.2%.

In the case of using commonly used ferro-manganese in the steelmaking process, the problem may be divided into carbon and phosphorus (P). That is, 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, but phosphorus (P) contains all of the high and heavy carbon, low carbon ferro-manganese, and alloy Even if the type of iron is changed, there is no way to avoid the effect of phosphorus (P) contained in ferro manganese.

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, in the case of using ferro-manganese ferroalloy, an increase in the concentration of phosphorus (P) in molten steel by the ferroalloy should be considered, which may cause the use of ferro-manganese.

In order to solve such a problem, it is necessary to manufacture low phosphorus ferro-manganese containing less phosphorus (P), and for this purpose, a method of beneficiation using only manganese ore having a low content of phosphorus (P) is used. However, in general, ores with low phosphorus (P) content are known to exhibit poor operability in an electric furnace reduction process, and the price of high-grade ores is increasing due to a decrease in reserves of high-quality manganese ores used for ferro-manganese. .

On the other hand, as the amount of low-grade ore is increased in the ferro-manganese manufacturing process, there is a problem in that the content of phosphorus in the ferro-manganese increases. Therefore, in some overseas research journals, when using low-grade ore with high phosphorus (P), ferromangan is manufactured after lowering the content of phosphorus in the ore by roasting or leaching.

As another method for preparing low-ferro-fermanganese, a method for producing low-carbon low-ferro-manganese is known by reducing slag or low phosphorus ore generated from high-carbon ferro-manganese with non-carbon-based reducing agents (Si, Al, Ca, etc.). Patents (US 4,282,032, US 4,363,657) and Japanese patents (JP 2006-161079).

In general, slag produced during the production of high-carbon ferro-manganese is present in the form of manganese oxide with little phosphorus content due to reduction of phosphorus in ore in the electric furnace, thus reducing the content of phosphorus in ferroalloy by reducing it with a non-carbon-based reducing agent. Can be made low. However, such a method uses a by-product generated in the manganese ferroalloy manufacturing process, a secondary ferro-manganese is produced by a high content of phosphorus, there is a problem that can not be produced in large quantities.

In order to solve such a problem, a method of manufacturing low-ferro-manganese by directly dephosphorizing in high-carbon ferro-manganese produced in an electric furnace is disclosed in US Patents US Pat. No. 4,662,937, US Pat. No. 4,684,403 and US 4752327, and various research papers.

The method for preparing low ferro-manganese can be largely divided into reduced and delineated tallin. Reduction Tallinn phosphide phosphorus (P) of ferro manganese _{(Ca 3 P 2, Mg 3} P 2 , etc.) is a method of removing in the form of oxide, Tallinn cargo phosphate phosphorus (P) of ferro manganese (Ba ₃ ( PO ₄ ) _2, etc.). In the case of reduced Tallinn, Ca or Mg is mainly used, but Ca is impossible to dephosphorize in high-carbon ferro-manganese due to the formation of carbides, and Mg is known to have a low delinquency efficiency without pressure refining due to high vapor pressure (US Patent US 4684403). ). It is also known that the Tallinn products Ca ₃ P ₂ and Mg ₃ P ₂ react with water to produce toxic gas, phosphine.

In case of deoxidation, BaCO ₃ , BaO, BaF ₂ , BaCl ₂ , CaO, CaF ₂ , Na ₂ CO ₃ , Li ₂ CO ₃ and the like are used. Among them, Ca-based materials have low de-lining efficiency, and Na and Li-based vapors have high vapor pressure, and thus BaCO ₃ or BaO is mainly used. Among them, BaO is known to use an oxidizing agent because there is no oxygen source capable of oxidizing phosphorus (P).

In case of deoxidation using BaCO ₃ or BaO, slag is generated in a solid phase, and dephosphorization efficiency is lowered. Thus, in order to solve this problem, BaCl ₂ (US Patent US 4752327), BaF ₂ or NaF (Domestic Patent 10-1036317) is used as a solvent. It is known to use. However, if BaCl ₂ is used, there is a problem of facility contamination due to highly corrosive Cl group or slag on top of ferro-manganese due to evaporation of Cl group, and flying away, and the price of the flux used is lower than that of ferro-manganese. There is a problem that it is difficult to establish an economical production process at a very expensive price. In addition, in the case of BaO-based flux, there is a problem that the water-soluble Ba component remaining in the slag or dust generated as a by-product elutes in the leachate, causing environmental pollution.

Accordingly, there is a demand for development of a flux for dephosphorization which can economically perform a dephosphorization reaction while having a high delinquency efficiency from ferromanganese.

In order to solve the problems enumerated above, an object of the present invention is to provide an alternative flux that can reduce the amount of BaO required in the flux used for delineation of ferromanganese.

In order to achieve the above object, the present invention provides a delineation flux for ferromanganes, which comprises a mixture of BaCO ₃ and SrCO _{3 in} the delineation flux for producing low ferro-manganese.

Here, SrO / (SrO + BaO) weight ratio may be in the range of 0.25 to 0.6, NaF is preferably included in the range of 5 to 10% by weight relative to the total weight of the flux as a solvent.

Hereinafter, the present invention will be described in detail.

Oxidation and delineation of ferro-manganese is known to form phosphorus (P ₂ O ₅ ) by phosphorus (P) in the manganese reacts with oxygen to be trapped by a high base material to become a stable phase. For this reason, highly basic oxides such as CaO or BaO are used. When using these high basic oxides, a solvent that lowers the melting point of the slag is used because it must be present in the liquid state to promote the reaction with the phosphate. The present invention provides a Ba-carbonate instead of ferro-manganese Tallinn flux to obtain the same level of the Tallinn efficiency by using a mixture of BaCO ₃ and SrCO ₃ SrCO ₃ mixed at a predetermined ratio to that commonly used.

Flux for dephosphorization according to the present invention has a very good dephosphorization ability in comparison with BaO-based fluxes used for dephosphorization of conventional molten ferro-manganese, and exhibits superior dephosphorization ability compared to conventional solvents even at high temperatures. In particular, when using the flux for Tallinn according to the present invention, the amount of slag generated as a by-product and the content of BaO in the slag is low, which greatly reduces the slag treatment cost.

1 is a graph showing the change in delineation rate according to the mixing ratio of SrO in the ferromangan delineation flux.
Figure 2 is a graph showing the change in delineation rate according to the temperature and the solvent content in the ferromangan delineation flux.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. These examples are merely illustrative of the present invention, and the scope of the present invention is not limited thereto.

Example

In this embodiment, to obtain a high basic flux that can replace BaCO ₃ used as a conventional ferro manganese dephosphorine flux, as shown in Table 1 below by mixing SrCO ₃ in a certain ratio and reacted with high-carbon ferro manganese Debinding ability was measured. The experimental method is as follows. 20 g of high-carbon ferro-manganese and 10% by weight of MnO were added to the magnesia crucible, and BaCO ₃ and SrCO ₃ were separately mixed in the weight ratio of Table 1 and added to the crucible so that the total was 6 g. The reason for adding MnO is to simulate the content of MnO, the main component of slag, before the ferromangan delineation. After the equilibrium reaction was carried out at 1350 ° C., 1400 ° C. or 1450 ° C. for 5 hours, the content of phosphorus (P) in ferromangan was measured. With the change in the concentration of phosphorus (P) before and after the experiment, the Tallinn rate was calculated according to the following equation.

Table 1 shows the relative dephosphorization ability according to the flux composition change, that is, BaO is replaced with SrO, and the solvent content of NaF is changed based on the dephosphorization rate of BaCO ₃ -5% NaF flux.

number SrO
wt% BaO
wt% MnO
wt% Solvent Temperature
℃ Tallinn compared to BaO
(1400 ° C., 5% NaF) Kinds Content (wt%) One 90 0 10 - - 1400 0.33 2 0 85 10 NaF 5 1400 1.00 (reference system) 3 17 68 10 NaF 5 1400 1.05 4 21.3 63.7 10 NaF 5 1400 1.25 5 34 51 10 NaF 5 1400 1.57 6 42.5 42.5 10 NaF 5 1400 1.67 7 51 34 10 NaF 5 1400 1.64 8 63.7 21.3 10 NaF 5 1400 0.69 9 85 0 10 NaF 5 1400 0.58 10 42.5 42.5 10 NaF 5 1450 1.34 11 42.5 42.5 10 NaF 5 1350 1.95 12 40 40 10 NaF 10 1400 1.72 13 40 40 10 NaF 10 1450 1.27 14 37.5 37.5 10 NaF 15 1400 1.23 15 37.5 37.5 10 NaF 15 1450 0.92

As shown in Table 1 above, when BaO was replaced with SrO at 1400 ° C. and NaF 5%, the desorption rate was high when the SrO / (SrO + BaO) ratio was 0.25 to 0.6 (see FIG. 1). If the ratio is larger than this, it can be seen that the drop in the amount of Tallinn decreases due to the decrease in the amount of liquid flux. This can also be confirmed that when the entire amount of BaO is replaced with SrO (No. 1), the Tallinn reaction hardly occurs. 1 is a graph showing the change in delineation rate according to the mixing ratio of SrO in the ferromangan delineation flux.

In addition, when the SrO / BaO weight ratio is 1.0 (No. 10-15), the change in delinquency ability according to the solvent content and the temperature change was tested. Figure 2 is a graph showing the change in the delineation rate according to the change in the solvent content and temperature in the ferromangan delineation flux. As shown here, as the temperature is increased, the Tallinn efficiency is lowered, and when the content of NaF added as a solvent is 5 to 10% by weight, the Tallinn efficiency is increased, but when the 15% by weight, it can be seen that rather reduced. This is because the effect of increasing the amount of liquid phase by the addition of the solvent is acting up to 5 to 10% by weight, and when added more, the delineation reaction is reduced due to the dilution effect of the basic flux SrO.

As can be seen from the above experimental results, by replacing the part of BaCO ₃ with SrCO ₃ in the ferromangan dephosphorization flux according to the present invention, not only can the delineation efficiency be improved, but also the amount of slag generated due to the low content of BaO in the slag generated as a by-product. It can reduce and solve the pollution problem.

As described above, it was described with reference to the drawings exemplified for the flux for ferromangan Tallinn according to an embodiment of the present invention. However, those skilled in the art will readily understand that the present invention is not limited to these embodiments and drawings, and that various modifications and variations are possible within the scope of the technical idea according to the present invention.

Claims (3)

Flux for delineation for producing low ferro-manganese, Flux for dephosphorization of ferro-manganese comprising a mixture of BaCO ₃ and SrCO ₃ and the SrO / (SrO + BaO) weight ratio ranges from 0.25 to 0.6. The flux for dephosphorization of ferro-manganese according to claim 1, comprising NaF in the range of 5 to 10% by weight and a residual amount of a mixture of BaCO ₃ and SrCO ₃ as solvents, based on the total weight of the flux. delete

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